Asymmetric hydrophilicity-driven fast water diffusion enabling heterogeneous hygroscopic gels toward high-yield atmospheric water harvest

Domain: biology
Published: 2026-03-28
Editorial outcome: major_revision

Abstract
Hygroscopic polymeric gels hold a promising avenue for sustainable sorption-based atmospheric water harvesting (SAWH). However, conventional designs relying on homogeneous hydrophilic networks face an inherent trade-off: strong hydrogen bond-mediated water retention and osmotic pressure-driven water transport. Here, we propose a strategy to construct heterogeneous structure composed of hydrophilic pectin shell and relatively hydrophobic graphene oxide (GO) sheets core for hygroscopic polymeric organgel integrated with glycerol. The pectin shell acts as a gas–liquid conversion interface, enabling continuous and efficient water condensation. The incorporation of pristine GO interlayers significantly reduces the interaction between adsorbed water molecules and hydrophilic functional groups. This configuration enhances glycerol-enabled osmotic pumping for rapid water transport into storage and supports efficient solar-driven water release. The resulting organgel exhibits a high water uptake capacity ranging from 0.83 to 6.57 g g-1 across a broad relative humidity spectrum (30% to 90%). Under 1.0 sun illumination, it achieves a notable desorption rate of 2.06 kg m-2 h-1, contributing to a daily water yield of up to 2.86 L kg -1day-1. This heterogeneous structure challenges the conventional paradigm of water sorbent maximizing hydrophilicity and supports the rational design of high-performance toward next-generation SAWH materials.

Introduction
Atmospheric water vapor as a vast yet underutilized freshwater source, holds three times the volume of all polar ice caps and rivers1,2. To effectively harness this moisture resource, sorption-based atmospheric water harvesting technology offers a sustainable solution applicable across diverse climates and geographical locations3,4. Typical sorbent materials, such as pore-confining hollow matrices5, linker-extended MOFs6, and capillary force-mediated fiber scaffolds7, have shown fast sorption kinetics but reached low moisture retention capacity owing to their non-swelling property. For sustainable hygroscopic capability, polymeric gels are emerging as promising candidate due to their chemically designable hydrophilic structure, reversible swollen capability, and high accessibility8,9. The alternative introduction of hygroscopic solid salts (e.g., LiCl, CaCl2, etc.)10,11 or liquid solvents (e.g., glycerol, ionic liquid, etc)8,12 into the polymeric crosslinked network can further enhance the sorption capacity. In a typical hygroscopic process, moisture is initially converted to the liquid state via a multistage sorption mechanism involving both chemisorption and deliquescence13. Subsequently, the liquid water molecules are gradually transported into the interior polymeric network driven by osmotic pressure, thereby reactivating the hygroscopic sites exposed to the surface of gels (Fig. 1a).

Conventional polymeric hygroscopic system focuses on constructing homogeneous porous structures, which suffer from low mass transfer velocity due to the strong interaction between hydrophilic polymer chains and water molecules14,15. Notably, a fundamental trade-off exists between chemical sorption and osmotic pressure transportation, in which hydrophilic chains can accelerate the moisture sorption, but reduce the water transportation velocity. To solve this issue, a series of pore engineering strategies (e.g., cryogelation5, foaming-drying16, templating17, vertical freezing18, bidirectional freezing19, etc.) are developed to enhance mass transfer kinetics by constructing a variety of macroscale, interconnected, vertically aligned and bidirectionally aligned pores for high capillary force. However, the optimal criteria for pore size and distribution are unclear and hard to achieve the structural balance between sorption and desorption processes. In addition, controllable and reliable fabrication strategies in a cost-effective and scalable way are highly urgent to achieve.

Here we propose a strategy to construct heterogeneous structure composed of pectin-graphene oxide (GO)-pectin-based hygroscopic organogel (HPGP) uniformly infused with glycerol, with high sorption capacity and rapid desorption rates. This structure achieves spatial decoupling of water capture and transport. The outer pectin-glycerol layers provide the thermodynamic driving force for vapor liquefaction via a strong osmotic gradient, while the central GO interlayers establish a kinetic pathway to sustain the process. Acting as a low-friction internal transport network, GO interlayers prevent surface saturation by rapidly channeling condensed water into the material’s core. This spatial decoupling prevents the captured water molecules from being overly immobilized by hydrogen bonds at the surface, thereby sustaining the high efficiency of the glycerol-driven osmotic pump. Additionally, the central GO interlayers exhibit a strong photothermal response and enable solar-driven water release, significantly boosting the overall desorption efficiency. As a result, HPGP achieves a high sorption capacity, ranging from 0.83 to 6.57 g g-1 at relative humidities of 30% to 90%; under 1.0 sun illumination, the desorption rate was up to 2.06 kg m-2 h-1, and more than 90% of the water was desorbed within 40 min. These features enable a HPGP-based SAWH device to produce up to 2.86 L water kg sorbent -1day-1, representing a performance highly competitive with the leading reported SAWH systems. This work provides valuable insights into designing high-performance sorbent materials and highlights a promising strategy to enhance moisture sorption-desorption performance in SAWH applications.

Results
Design and construction of HPGP
Supplementary Figure. 1 illustrates the preparation process of HPGP. Initially, GO interlayers are prepared by continuously drying a GO suspension, forming the intermediate layer with a multilayered and wrinkled structure. Subsequently, the GO interlayers are uniformly coated with pectin on both sides and crosslinked with Zn2+ to enhance structural integrity, yielding a heterogeneous pectin-GO-pectin structure. Finally, the resulting pectin-GO-pectin is fully immersed in an excess of glycerol, resulting in the pectin-GO-pectin-based hygroscopic organogel. In this design, the outer pectin layers function as the primary hydrophilic modules, leveraging their abundance of functional groups to provide outstanding gas-liquid conversion, facilitating the initial capture and liquefaction of atmospheric vapor on the HPGP surface.

The GO interlayer, in contrast, is engineered to act as a high-speed water diffusion module. This function arises from its intrinsic material properties; GO inherently possesses a much lower density of hydrophilic groups compared to the surrounding pectin network. Following glycerol infusion process, these GO channels become filled with glycerol, creating a liquid medium with relatively weak interactions with transient water molecules. Consequently, when water captured by the pectin migrates into these channels, it experiences significantly reduced hydrogen-bonding confinement, enabling rapid, low-resistance transport driven by osmotic pressure towards the interlayer interfaces and interlamellar spaces (Fig. 1c). This efficient transport maximizes the occupancy of available sorption sites throughout the material, while the wrinkled topography of the GO interlayers further expands the surface area to boost overall sorption capacity. Additionally, the GO interlayer serves as an independent and efficient photothermal medium. Its multilayered structure, combined with a dual-sided evaporation configuration, facilitates the rapid desorption of water molecules from the interlayer spaces during the release phase (Fig. 1b, c). In stark contrast, a conventional homogeneous pectin-GO hydrogel fabricated through simple physical blending results in a disordered polymer network. In such a structure, the three-dimensional framework constructed through dense hydrogen-bond interactions between pectin chains and GO nanosheets imposes severe spatial confinement on water molecules. This combination of steric hindrance and strong intermolecular attraction significantly impedes water penetration and diffusion. Consequently, the high mass-transfer resistance inherent in this homogeneous structure leads to suboptimal water harvesting performance when compared to our rationally designed heterogeneous HPGP system (Fig. 2a, b).

Macroscopic observations and transmission electron microscopy (TEM) analysis indicate that the GO interlayers exhibit significantly rougher wrinkles and a more compact three-dimensional structure compared to the flat GO interlayers. (Supplementary Fig. 2). Additionally, glycerol infusion induced a contraction in the pectin layer, decreasing its diameter from 50 mm to 40 mm (Fig. 2c). This contraction is attributed to the fact that glycerol forms hydrogen bonds between the pectin layer and the GO interlayers, enhancing their coupling and stabilizing the heterogeneous structure (Fig. 2d and Supplementary Fig. 3). After sorption, the HPGP material retains the absorbed water without leakage, undergoing significant volumetric expansion (Fig. 1d). To verify the heterogeneous structure of HPGP, scanning electron microscopy (SEM) was employed. The results indicate that HPGP is composed of an upper and lower pectin layer with four intermediate GO layers, yielding an overall thickness of approximately 100 μm (Fig. 2e, i-ii). Moreover, the introduction of the pectin layer does not alter the surface wrinkles of HPGP (Fig. 2e-iii and Supplementary Fig. 4). Energy dispersive spectroscopy (EDS) elemental mapping reveals a uniform distribution of carbon (C), oxygen (O), and zinc (Zn) throughout the HPGP, ensuring structural uniformity and facilitating the formation of a robust cross-linked network (Supplementary Figs. 5 and 6).

Fourier transform infrared (FTIR) spectroscopy of the Zn2+-cross-linked pectin layer shows a characteristic absorption peaks at 1750 cm-1, corresponding to carbonyl (Fig. 2f)20. This cross-linking mechanism is further substantiated by X-ray photoelectron spectroscopy (XPS) (Fig. 2g, h and Supplementary Note 1)21. As evidenced by contact angle measurements, water droplets fully spread over the surfaces of flat GO interlayers, wrinkled GO interlayers, and HPGP within 30 milliseconds, highlighting their excellent hydrophilicity (Supplementary Fig. 7).

Mechanism for moisture sorption of HPGP.
Acting as a gas-to-liquid converter within the heterogeneous HPGP structure, the outer pectin layer leverages abundant hydroxyl and carboxyl groups21 (Fig. 2c) to establish hydrogen bonds with water molecules, enabling efficient capture of atmospheric water vapor (Supplementary Fig. 8). The interlayer moisture-absorbing medium, glycerol, then facilitates water transport from the pectin reservoir into the GO interior, driven by osmotic pressure. Molecular dynamics (MD) simulations reveal that within HPGP, a single water molecule interacts with four glycerol molecules (Fig. 3a), driving continuous water transport inward. This process reactivates moisture-sorption sites on the HPGP surface, enabling rapid and repeated moisture sorption8. Upon entering the GO interlayers, water molecules initially bind to the hydroxyl and carboxyl groups of the graphene sheets. While this forms an initial layer of stabilized bound water (Fig. 3a), crucially, the continuous supply from the pectin reservoir rapidly saturates these surface binding sites. Once the hydration shell is established, subsequent water molecules are shielded from strong surface interactions. Consequently, excess water accumulates in the center of the interlamellar spaces and within the wrinkles of the GO structure (Supplementary Fig. 9). Unlike the sluggish surface-bound water, this accumulated water acts as free water with high mobility, creating high-speed nanofluidic channels. Under solar irradiation, the GO interlayers absorb energy, disrupting hydrogen bonds of surface-bound water molecules and weakening the cohesive interactions of intermediate water. This energy transfer expedites desorption, while excess energy propagates to the solution and the pectin layer, thereby enhancing water removal efficiency (Supplementary Fig. 9).

Crucially, the incorporation of pure GO interlayers in heterogeneous structure significantly reduces interactions between captured water molecules and hydrophilic groups. This reduction allows liquefied water molecules to be propelled rapidly along the GO interfaces by osmotic pressure. In contrast, the homogeneous structure exhibits excessive hydrogen bonding traps water molecules within the pectin chain network, restricting their mobility and thus limiting diffusion. Furthermore, the mixing process promotes chain entanglement, creating steric hindrance that constricts water migration pathways. Consequently, this leads to significantly slower migration kinetics compared to heterogeneous structure. MD simulations at t = 800 ps reveal limited water penetration into homogeneous structure, exhibiting low diffusion rates and insufficient occupation of internal sorption sites (Fig. 3c and Supplementary Fig. 10). In sharp contrast, at the same time point, water molecules in heterogeneous structure successfully penetrate the GO interlayers and progressively occupy internal sorption sites (Fig. 3b and Supplementary Fig. 11). Additionally, the mean squared displacement (MSD) is directly correlated with the diffusion coefficient (D) of water molecules, where D is calculated as one-sixth of the slope of the MSD-t curve. MSD quantifies the average change in displacement over time and describes particle displacement as time increases. Our analysis (Fig. 3d, e and Supplementary Fig. 12) shows that the diffusion coefficient D of water molecules in heterogeneous structure is approximately 204.03, a value substantially higher than the 181.16 observed in the homogeneous structure. This elevated diffusion rate directly corroborates the existence of highly mobile water within the GO channels.

To experimentally validate this simulation-predicted high-mobility state, LF-NMR measurements were performed. The results reveal a critical humidity-dependent transition facilitated by this specific structure (Fig. 3f). At low humidity (30% RH), the spectrum is dominated by bound and intermediate water signals, confirming the role of the outer pectin layers in initially capturing atmospheric moisture. Strikingly, at 90% RH, a distinct and substantial population of free water (>100 ms) emerges. This behavior contrasts sharply with the control experiments on individual components (Supplementary Note 2 and Supplementary Fig. 13). While pure pectin primarily constrains water within the intermediate range and pure GO exhibits signals characteristic of surface-interacting water, the HPGP demonstrates a clear structural synergy. The hygroscopic pectin coating acts as a saturated reservoir, effectively pumping captured moisture into the GO interlayers. This ensures the graphene nanocapillaries are fully flooded, allowing water to transition from a surface-bound state to a highly mobile, bulk-like fluid state. This direct observation confirms that the heterogeneous structure not only captures water but effectively activates high-speed transport channels. These findings demonstrate that the heterogeneous structure of HPGP, coupled with osmotic pressure modulation, synergistically enhances both moisture sorption capacity and diffusion kinetics.

Sorption capacity of HPGP
The heterogeneous structure is critical to the sorption capacity of HPGP, which is 61.8% higher than that of the homogeneous structure (Fig. 4a). To elucidate its functional mechanism, the individual components of the HPGP were systematically evaluated for moisture sorption performance under 25 °C and 90% RH. As shown in Supplementary Fig. 14, Pectin, GO interlayers, and Pectin-GO interlayers-Pectin exhibited minimal sorption capacities of 0.98 g g-1, 0.03 g g-1, and 1.04 g g-1, respectively. In contrast, HPGP achieved a markedly higher sorption capacity of 6.57 g g-1. This enhancement establishes the critical role of heterogeneous structure in sorption capacity. The GO interlayers serve as the core multilayered framework, and their sorption capacity is highly dependent on both the number of layers and the presence of surface wrinkles. As shown in Fig. 4b, increasing the number of GO interlayers in HPGP from two to four enhances its sorption capacity from 4.28 g g-1 to a maximum of 6.57 g g-1. However, when the number of GO interlayers reaches five, the sorption capacity begins to decrease, falling from 6.52 g g-1 to 6.28 g g-1. This decrease occurs because adding a single GO interlayer does not appreciably increase the glycerol content within HAPGP. Instead, the additional layers impede water molecule transport, thereby hindering moisture sorption (Supplementary Fig. 15 and Supplementary Note 3). Furthermore, as the number of GO interlayers increases beyond four, the loss of surface wrinkles further diminishes sorption capacity. To investigate the role of surface wrinkles, we compared the sorption capacities of HPGP and pectin-flat GO interlayers-pectin (which is devoid of surface wrinkles). As illustrated in Supplementary Fig. 16, HPGP demonstrated a 16.6% improvement in sorption capacity over pectin-flat GO interlayers-pectin at 25 °C and 90% RH, highlighting the importance of wrinkles in promoting moisture uptake. We also evaluated the effect of pectin layer thickness on the sorption capacity of HPGP. The sorption curve in Fig. 4c shows that GO interlayers soaked in glycerol but not coated with pectin exhibit a sorption capacity of only 2.97 g g-1. However, applying a pectin coating to the GO interlayers substantially elevates sorption capacity. As shown in Fig. 4c, increasing the pectin layer thickness from 10 to 30 μm boosts the sorption capacity to a maximum of 6.57 g g-1. The optimal performance at 30 μm is attributed to a balanced combination of glycerol content and pectin layer thickness (Supplementary Fig. 17). A thinner pectin layer (<30 μm) provides insufficient sorption sites and surface area, resulting in inadequate gas-liquid conversion and reduced sorption capacity. This insufficient coating also fails to meet the permeation requirements of glycerol. Conversely, a thicker pectin layer (>30 μm) increases structural complexity and pore resistance, extending the water molecule diffusion pathway. Consequently, water molecules accumulate on the pectin surface rather than penetrating the HPGP interior, ultimately reducing sorption capacity. Therefore, a delicate balance is struck at a pectin thickness of 30 μm, which, combined with four GO interlayers, maximizes the moisture uptake to 6.57 g g⁻¹ (Fig. 4d). Subsequently, X-ray Diffraction (XRD) was used to probe the GO interlayer structure (Supplementary Fig. 18). The pristine GO d-spacing of 1.13 nm expanded to 1.35 nm after glycerol intercalation, confirming the formation of nano-channels. Upon hydration, the d-spacing increased to 1.48 nm (at 30% RH) and remained stable at this value even at 90% RH. This indicates a structurally stable, water-saturated channel network at high humidity, which provides the physical conduits for rapid diffusion.

To further verify the advantage of heterogeneous structure in achieving high sorption capacity, we calculated the diffusion coefficient of moisture sorption (Dms) using Fick's second law (Fig. 4e and Supplementary Fig. 19). The formula is calculated as follows22:
Mt/Me = 2(Dt/πd^2)^1/2 (1)
where Mt and Me represent the mass of moisture sorbed at time t and at equilibrium, respectively, throughout the sorption process. As anticipated, under various RH conditions at 25 °C, the experimental values of Mt/Me exhibit an ideal linear fit with the square root of time in both the functional relationship plots and the linear regression analyses, aligning closely with the proposed theoretical model (Supplementary Table 1). As depicted in Supplementary Fig. 19, the heterogeneous structure exhibits a higher moisture sorption Dms, reaching values of 1.02×10-7, 0.78×10-7, and 0.79×10-7 cm2 s-1 at 30%, 60%, and 90% RH, respectively. In contrast, the homogeneous structure attains lower Dms values of 0.50×10-7, 0.52×10-7, and 0.54×10-7 cm2 s-1 under these same relative humidity conditions. Furthermore, HPGP demonstrates excellent moisture sorption capacity, achieving values of 0.83 g g-1, 2.97 g g-1, and 6.57 g g-1 at 25 °C under relative humidity conditions of 30%, 60%, and 90%, respectively, which highlights its suitability for SAWH across diverse climates (Supplementary Figs. 20). Notably, HPGP retains the absorbed water within its structure in an expanded form without leakage. After three days of sorption, HPGP undergoes significant volume expansion (Supplementary Fig. 21). Meanwhile, its liquid retention capability was verified through centrifugation tests and long-term stability tests, while the high purity of the harvested water (free of any leached components from the hygroscopic solution) provided more conclusive proof (Supplementary Figs. 22, 23 and Supplementary Note 4). Consequently, HPGP surpasses most previously reported high-performance and different structural design sorbent materials in moisture sorption capacity (Fig. 4f, Supplementary Figs. 24, 25 and Supplementary Tables. 2, 3)8,10,23–28,19,29–31.

Solar-driven water desorption performance of HPGP
The desorption performance of sorbent materials is influenced by their ability to absorb solar energy. Both the GO interlayers and the HPGP demonstrate outstanding broadband solar absorption, achieving efficiencies of 96.9% and 96.6%, respectively, over the wavelength range of 300 to 2,500 nm (Fig. 5a). In contrast, pectin displays a significantly lower solar absorption efficiency of only 43.9%. These results confirm that the GO interlayers function as a photothermal component, which facilitates rapid water desorption. To specifically isolate the contribution of the wrinkled topography to this high absorbance, we compared HPGP with a flat control (pectin-flat GO interlayers-pectin). The wrinkled HPGP achieved a solar absorbance of 96.9%, significantly surpassing the 90.1% of the flat GO interlayers (Supplementary Fig. 26). The wrinkles act as optical cavities that trap light via multiple internal reflections, extending the optical path length to maximize solar absorption. Under 1.0 sun illumination, HPGP demonstrates rapid thermal response characteristics equivalent to its constituent GO interlayers, attributed to the inherited photothermal conversion efficiency of the GO framework. Crucially, the transparency and minimal thickness of the pectin layer contribute to a negligible temperature variation of less than ±2 °C (Fig. 5b and Supplementary Fig. 27). To evaluate its photothermal conversion efficiency, HPGP samples, pre-saturated with moisture at 25 °C and 90% RH, were subjected to solar radiation at intensities ranging from 0.7 to 1.6 suns. With increasing solar intensity, the surface temperature of HPGP stabilized within 10 minutes, attaining steady-state values of 49.7, 55.3, 60.8, and 69.7 °C, respectively (Fig. 5c and Supplementary Fig. 28). The desorption performance of HPGP also increased with rising surface temperatures. Over 25 minutes, the desorption performance of HPGP under solar intensities of 0.7, 1.0, 1.3, and 1.6 suns was 0.63, 1.03, 1.32, and 1.72 kg m-2, respectively (Fig. 5f). Notably, even under standard 1.0 sun illumination, HPGP achieved a peak desorption rate of 0.31 g g-1 min-1 within 40 minutes, releasing over 90% of its absorbed water (Supplementary Fig. 29). This efficient water desorption performance is further enhanced by the double-sided wrinkled evaporation structure of GO interlayers, which mitigates vapor accumulation by providing additional escape paths and a broader diffusion space for water vapor (Supplementary Fig. 30)32. Notably, the superior light-trapping capability of the wrinkled HPGP directly translates to enhanced thermal performance. Under different sun illumination, the surface temperature of HPGP is consistently higher than that of pectin-flat GO interlayers-pectin (Supplementary Figs. 28, 31 and 32). As indicated in Supplementary Figs. 33 and 34, under 1.0 sun illumination, the introduction of surface wrinkles increases the steady-state surface temperature from 51.4 °C (for pectin-flat GO interlayers-pectin) to 55.3 °C (for HPGP) and enhances the mass change rate from 0.75 kg m-2 to 1.03 kg m-2. These findings confirm that the structural features of GO interlayers play a crucial role in amplifying the photothermal and desorption performance of HPGP.

The desorption performance of sorbent materials is influenced not only by their capacity to absorb solar energy but also by the distribution of the heat-absorbing medium33. Fig. 5d and Supplementary Fig. 35 illustrate two distinct thermal transport dynamics, demonstrating the superiority of the internal heating mode in HPGP over the conventional surface heating of homogeneous structure. The homogeneous structure, with its evenly dispersed GO, concentrates heat generation at the top surface. This creates a thermal bottleneck and an inefficient outside to inside thermal gradient, where heat must slowly conduct through the pectin hydrogel matrix, leading to significant surface energy loss and a delayed thermal response. In stark contrast, the heterogeneous architecture of HPGP enables an efficient inside to outside heating mode. As directly confirmed by thermal imaging, its centrally located GO interlayers act as a dedicated internal heat source. This internal heating mechanism minimizes surface losses and ensures efficient inside to outside heat diffusion, delivering thermal energy directly to the stored water and thus accelerating the overall temperature rise. This fundamental difference in heat management directly accounts for the enhanced desorption kinetics observed. Under 1.0 sun illumination, the heterogeneous structure achieves a surface temperature 7 °C higher than that of the homogeneous structure, resulting in a 0.43 kg m-2 increase in desorption performance (Fig. 5e). Critically, Fig. 5f shows that the internal heating design has a nearly instantaneous desorption onset, characterized by an immediate, steep mass loss. The homogeneous structure, however, exhibits a significant thermal lag period with minimal mass change before effective desorption begins. In terms of desorption rate heterogeneous structure was able to reach a rate of 0.31 g g-1 min-1, outperforming the homogeneous structure (0.098 g g-1 min-1) by a factor of 3.2 (Supplementary Figs. 36 and 37).

To further assess the desorption kinetics, we calculated the hydrolysis diffusion coefficient (Dwd) using Fick's second law34:
(X-Xt)/(X-Xe) = 1 - (8/π^2)exp(-π^2 Dwd t / d^2) (2)
where X0, X, and Xe represent the initial mass, mass at time 𝑡, and mass at desorption equilibrium, respectively, while d denotes the sample thickness. Plotting the experimental data of (X-Xt)/(X0-Xe) versus the square root of time demonstrated excellent agreement with the theoretical model under various solar illumination conditions. The heterogeneous structure exhibited accelerated desorption kinetics compared to the homogeneous structure (Fig. 5g). The heterogeneous structure exhibited an initial slow desorption rate, followed by a rapid increase (Supplementary Fig. 38). This behavior is attributed to the pectin, which lacks a heat-absorbing medium, heating up first and initiating desorption. During this stage, incomplete heating of the GO interlayers causes a slow desorption rate. Subsequently, as the GO interlayers accumulate sufficient thermal energy, they release water molecules from both their surface and interior, leading to an acceleration in desorption. Consistent with these observations, the heterogeneous structure exhibited higher Dwd values under solar illumination intensities of 0.7, 1.0, 1.3, and 1.6 suns, with respective values of 4.89×10-6, 8.38×10-6, 13.16×10-6, and 15.67×10-6 cm2 s-1. In contrast, the homogeneous structure recorded substantially lower Dwd values of 3.54×10-6, 4.15×10-6, 6.60×10-6, and 9.39×10-6 cm2 s-1 under the same conditions (Fig. 5g and Supplementary Table 4). Furthermore, a comparative analysis of water desorption kinetics with existing sorbent materials underscores the superior performance of HPGP (Fig. 5h, Supplementary Fig. 39 and Supplementary Tables 5, 6)8,23,25,26,29,31,24,35–37.

Demonstration of the outdoor water-harvesting tests
The synergistic combination of high sorption capacity and rapid desorption in HPGP ensures efficient water production across diverse environments, positioning it as a promising solution for practical atmospheric water harvesting (Supplementary Fig. 40). To validate its real-world applicability, we engineered an integrated device capable of performing both moisture sorption and desorption cycles. The device consists of six HPGP units, a water collection container with dual-end vents for air circulation, support frames for optimal air exposure to the HPGP, a transparent acrylic cover for solar penetration, and a shade hood for shading (Fig. 6a). The shading hood allows HPGP to absorb water molecules even during daylight, enhancing its operational flexibility. Specifically, in a three-day outdoor moisture sorption experiment, the shading hood was used to create a dark environment, preventing premature solar desorption of HPGP. Simultaneously, the dual-end vents of the water collection container were opened, ensuring continuous air circulation and full contact between the air and the HPGP, thereby completing the sorption process (Fig. 6b). For the desorption phase, the shade hood was replaced by a transparent cover, and the vents were sealed to create an enclosed environment. Sunlight then triggered the desorption of HPGP, with water vapor visibly condensing on the interior walls of the device (Fig. 6a). Figure 6c shows average changes in ambient temperature and relative humidity during the three-day experiment. The temperature ranged from 23.2 °C to 31.5 °C, while RH varied between 82.6% and 72%. Operating under these ambient conditions, the device collected a total of 8.703 g of water, with daily yields of 5.215 g, 2.173 g, and 0.815 g, respectively (Fig. 6d, Supplementary Fig. 41 and Supplementary Note 5). Based on the first-day water production, the sorbent achieved a remarkable freshwater productivity of 2.86 L water kg sorbent -1day-1, a value that surpasses most leading sorbents developed for SAWH systems (Fig. 6g and Supplementary Table 7)19,27,38,18,39,30,40–42. The innovative sorption-desorption cycle allows HPGP to operate effectively even in environments lacking sunlight, ensuring sustained water production and enhanced overall efficiency. To affirm its generalizability, the HPGP system was further tested in contrasting climates, demonstrating excellent adaptability. It achieved a notable water productivity of 2.63 L water kg sorbent -1day-1 in a low-temperature, high-humidity environment (7.6–16 °C, RH up to 92%) and 1.96 L water kg sorbent -1day-1 under higher-temperature, semi-arid conditions (17.7–22.5 °C, RH ~60%), confirming its viability for diverse geographical deployment (Supplementary Figs. 42-45 and Supplementary Note 6). During the desorption phase, natural sunlight achieved a water collection efficiency of 86%, slightly lower than the efficiency observed under controlled laboratory conditions (Supplementary Fig. 46 and Supplementary Note 7). These results highlight the practical potential of HPGP for efficient and sustainable SAWH across diverse environmental conditions.

The stability of internal glycerol and the purity of the desorption process were rigorously investigated. Analysis of the vapor phase via Fourier-transform infrared spectroscopy (FTIR) confirmed the absence of evaporated glycerol; specifically, while strong absorption peaks corresponding to the O-H bonds of water were observed (3300–3800 cm-1), the characteristic C-H absorption peaks of glycerol (2500–3000 cm-1) were undetectable (Supplementary Fig. 47). This was further corroborated by gas chromatography-mass spectrometry (GC-MS), which revealed no molecular glycerol or its thermal decomposition byproducts in the gas phase, only residual atmospheric components (Supplementary Figs. 48-50). Consequently, the harvested water exhibited exceptional purity. Its total organic carbon (TOC) level was minimal (<5 mg L-1), on par with deionized water, confirming no organic leaching. Moreover, inductively coupled plasma mass spectrometry (ICP-MS) analysis showed no zinc ion leakage and verified that the water quality complies with World Health Organization (WHO) standards (Fig. 6e and Supplementary Table 9). Beyond its water production capabilities, the heterogeneous structure of HPGP supports its environmental sustainability through easy disassembly. Specifically, the pectin layer, composed of biodegradable biomass material, poses no environmental threat, while the GO interlayers are reusable, enabling continuous recycling in HPGP production (Supplementary Figs. 51 and 52). To evaluate the recycling stability of GO interlayers, we conducted a series of 15 cycles over 45 days. The results demonstrated that HPGP assembled with recycled GO interlayers retain excellent sorption and desorption performance, with minimal deviation across multiple cycles, and the samples retained morphological stability before and after the hygroscopic cycle. (Fig. 6f and Supplementary Fig. 53). Furthermore, Raman spectroscopy confirmed that the ID/IG ratio remained unchanged after hydration cycles, demonstrating the structural and chemical stability of the GO nanosheets throughout the process (Supplementary Fig. 54). To validate outdoor applicability, HPGP was subjected to rigorous environmental testing. The pectin layer exhibited exceptional stability, maintaining structural integrity and resisting airborne microbial adhesion under UV irradiation, temperature and humidity cycling, and dust exposure, with colony analysis revealing negligible microbial colonization during simulated operation (Supplementary Figs. 55, 56 and Supplementary Note 8). This operational durability complements the biodegradability of pectin layer: in contrast to the surface during use, soil-buried samples were rapidly decomposed by diverse microorganisms, mitigating environmental pollution (Supplementary Fig. 56 and Supplementary Table 8). These findings highlight the durability and sustainability of the HPGP-based SAWH device, which can operate reliably across varying climatic conditions and day-night cycles. This makes HPGP a promising solution for diverse SAWH applications.

Looking beyond the proof-of-concept demonstration, we project a clear path for the HPGP organogel toward practical application, built upon three pillars: economic viability, scalability, and sustainability. Based on low-cost, abundant materials (pectin, graphite, glycerol, anhydrous zinc acetate), the system ensures its economic feasibility. Meanwhile, its ambient, water-based synthesis is fundamentally compatible with scalable, continuous manufacturing techniques like roll-to-roll processing (Supplementary Fig. 57 and Supplementary Note 9, 10). Furthermore, the sample preparation is highly robust, with controlled solution diffusion and drying steps ensuring uniform wrinkle formation, which is critical for consistent performance at scale (Supplementary Figs. 58 and 59). Most critically, its biodegradable shell-recyclable core design promotes a circular lifecycle: the pectin shell can be composted, while the valuable GO core can be recovered and reused. This synergy of economic viability, manufacturing scalability, and end-of-life sustainability underscores the profound translational potential of the HPGP system as a transformative, eco-friendly technology for atmospheric water harvesting.

Methods
Materials: Pectin, anhydrous zinc acetate (≥99.0%), concentrated sulfuric acid (H2SO4, 95–98 wt.%, AR), phosphorus pentoxide (P2O5, ≥98.0%), potassium persulfate (K2S2O8, ≥99.0%), potassium permanganate (KMnO4, ≥99.0%), hydrogen peroxide (H2O2, 30 wt.%, AR), poly(vinyl alcohol) (PVA, ≥98.0%), konjac glucomannan (KGM), sodium alginate (SA) and hydrochloric acid (HCl, 36–38 wt.%, AR) were purchased from Macklin (Shanghai, China). Glycerol (≥99.0%, AR) and anhydrous ethanol (≥99.7%, AR) were provided by Tianjin Hengxing Chemical Reagent Co., Ltd. (Tianjin, China). Graphene powder (325 mesh, 99.9 wt.%) was purchased from Qingdao Huatai Carbon Co., Ltd. (Qingdao, China). All commercial chemicals were used as received without further purification. Deionized water was used in all experiments.

Synthesis of GO interlayers: GO was prepared from 325-mesh graphite by a modified Hummers method43with pre-oxidation. Graphite (5.0 g) was treated in concentrated H2SO4 (40 mL) with P2O5 (8.42 g) and K2S2O8 (8.43 g) at 80 oC for 5 h, then diluted with water (150 mL), filtered (0.45 μm), washed with water (1.6 L), and dried (60 °C). The pre-oxidized product was dispersed in chilled concentrated H2SO4 (250 mL, ~0 °C); KMnO4 (30 g) was added, reacted at ~0 °C for 30 min and 35 °C for 2 h, then water (400 mL) was added and maintained at 35 °C for 2 h. The mixture was diluted (water, 1.2 L) and quenched with H2O2 (30 mL) to bright yellow, washed with HCl: H2O = 1:10 (1 L ×2) and water (1 L ×3), centrifuged (8000 rpm, 10 min ×3), and dialyzed (MWCO 8000–14,000) for 2 weeks. We prepared a 1:3 ratio mixture of deionized water and anhydrous ethanol, with volumes of 2.5 mL and 7.5 mL, respectively. Subsequently, 2 mL of 10 mg mL-1 GO solution was added to the mixture and stirred using a magnetic stirrer to ensure uniform dispersion of GO. Subsequently, the uniformly mixed GO solution was spread on a petri dish and dried in a 75 °C oven for 75 minutes, with intermittent vent opening to obtain GO interlayer. This process was repeated four times to obtain a four-layered GO interlayers with the maximum number of wrinkles (Supplementary Figs. 60, 61 and Supplementary Note 11).

The preparation of flat GO interlayers involves directly spreading an equal concentration of pure GO solution onto a petri dish. Once the surface of the liquid is even and smooth, it is placed into a ventilated drying oven at 75 °C for 75 minutes. This process is then repeated four times to obtain a four-layered GO interlayers.

Preparation of pectin-graphene oxide-pectin-based hygroscopic organogel: 1.5 g of pectin powder was added to 50 mL of deionized water under continuous magnetic stirring until complete dissolution was achieved. This mixture was used as an adhesive layer, wrapping a four-layered GO interlayers in a heterogeneous structure, and dried in a 60 °C oven for 10 minutes. The dried sandwich structure was immersed in a 0.1 M zinc acetate solution for 10 minutes, rinsed with deionized water after pectin crosslinking, and then soaked in sufficient glycerol for 36 hours to ensure solvent exchange. Excess glycerol was removed from the surface using filter paper, and periodic weighing was conducted to monitor the solvent exchange. Finally, remove the pectin-graphene oxide-pectin-based hygroscopic organogel, the excess glycerol on its surface was well absorbed with filter paper, and then weigh it to determine its initial mass.

Homogeneous pectin-GO, was mixed using the same materials, dried in the same way, immersed in zinc acetate and finally immersed in glycerol to obtain the homogeneous pectin-GO (Supplementary Fig.62).

Characterization: Sample morphology was characterized using scanning electron microscopy (SEM, FEI Quanta FEG650) operated at an accelerating voltage of 10 kV. Prior to imaging, the samples were mounted on conductive adhesive tabs and sputter-coated with a thin Au layer for 120 s using a plasma sputtering coater to improve surface conductivity and suppress charging. Elemental analysis was performed by energy-dispersive X-ray spectroscopy (EDS) using an EDAX Octane detector integrated into the SEM. EDS point spectra and elemental mapping were acquired at 10 kV with a live acquisition time of 60 s. Transmission electron microscopy (TEM) was conducted on an HT7800 operated at 200 kV. Samples were ultrasonically dispersed in ethanol, drop-cast onto carbon-supported copper grids, and air-dried at room temperature prior to observation. No additional staining was applied. Blue false coloring was applied to the SEM images to distinguish the layers; the color overlay was generated by image blending and superimposition in Microsoft PowerPoint 2019 (Microsoft Office). X-ray photoelectron spectroscopy (XPS) was carried out on modified pectin and unmodified pectin using an ESCALab MKII X-ray photoelectron spectrometer. X-ray diffraction (XRD) analysis was performed on a Rigaku SmartLab to measure the d-spacing of the GO interlayers in various states. Raman spectroscopy (Renishaw inVia Reflex) was employed to monitor the evolution of the ID/IG ratio in the GO interlayers throughout the cycling process. The wetting properties of GO interlayers, flat GO interlayers, and HPGP surfaces were assessed using a JGW-360A contact angle goniometer. Functional groups of the samples were analyzed using Fourier transform infrared spectroscopy (FTIR, Thermo Nicolet iS5) within the 400-4000 cm-1 range. The absorbance of GO interlayers, pectin, and HPGP was measured using a UV-Vis-NIR (Shimadzu UV-3600) in the wavelength range of 250 to 2500 nm. The water quality was determined using inductively coupled plasma mass spectrometry (ICP-MS, iCAP PRO with an instrumental LOD of 0.03 μg L-1). The total organic carbon (TOC) content in the collected water was measured using a TOC analyzer (SHIMADZU-TOC-L CPH with an instrumental LOD of 0.05 mg L-1). The leakage of glycerol was assessed using gas chromatography-mass spectrometry (GC-MS, Agilent 8860 GC System with an instrumental LOD of 0.1 mg L-1). A sealed plastic container with desiccant was used to prevent moisture sorption during sample transfer. Microbial community analysis: Sample DNA extraction and PCR amplification. Total microbial DNA was extracted from 0.5 g of fresh soil using a soil DNA kit (Hangzhou Bioer Technology Co., Ltd.) according to the manufacturer’s instructions, with three replicates for each soil sample. After DNA extraction, agarose gel electrophoresis was used to confirm the purity and integrity of the extracts. High-throughput sequencing was employed for comprehensive analysis of the microbial community in the soil samples. Subsequently, PCR amplification was performed using the universal primer pair 515F and 806R targeting the bacterial 16S rRNA gene region. High-quality sequencing data were obtained with the support of the TruSeq and HiSeq 2500 sequencing platforms. The data were subjected to strict quality control and processing. OTU clustering was conducted using USEARCH at a 97% sequence-identity threshold, and taxonomic annotation was performed using the SILVA database. Microbial diversity in the samples was evaluated using alpha-diversity indices. Community structure profiling was carried out in R, including various data transformations, and plots were generated using the ggplot2 package.

Moisture sorption experiments: First, HPGP, unsoaked glycerol molecules of GO interlayers, unsoaked glycerol molecules of pectin, soaked glycerol molecules of pectin, soaked glycerol molecules of GO interlayers, and glycerol were all placed together in a constant temperature and humidity chamber (LT-TH-150F) at 25 °C and RH 30%, 60%, and 90%. The mass changes of all samples were monitored dynamically using an electronic balance (FA2004) with fixed time measurements. Each test included five sets of samples, and the average values were calculated for statistics. The formula for calculating moisture sorption is as follows:
Water uptake = (m - m0) / m0 (3)
where m denotes the adsorbed mass of water molecules by the sample at different times, and m0 denotes the initial mass of the sample before sorption.

Water desorption experiments: Preparation of GO interlayers for immersed glycerol molecules, pectin for immersed glycerol molecules, HPGP, and homogeneous pectin-GO was carried out for the sorption of water molecules at 25 °C and 90% RH until all the samples were saturated. Samples were prepared at a room temperature of ~25 °C and 55% RH, and the solar light intensity was simulated using a xenon light source (Solar-500). Each test included five sets of samples, and the average values were calculated for statistics. During temperature testing, changes in sample mass and temperature were recorded using an electronic balance (FA2004) and an infrared camera (FLIR E5xt Wifi). After the start of the test, the temperature and the average rate of change of the sample mass were obtained every minute by the following equations:
Mc = ms - md (4)
Evaporation rate = Mc / T (5)
where Mc is the real-time mass per unit area, md is the real-time mass of the sample during desorption, ms is the mass of the saturated sample, and T is the time elapsed during desorption.

Water collection experiments: In an outdoor experiment at the Functional Polymer Laboratory of Central South University of Forestry and Technology in China. During the testing period, variations in weather conditions were monitored using a temperature and humidity recorder (COS-03, Shandong Renke Measurement and Control Technology Co., Ltd.), with an accuracy of ±2 °C and ±2% RH. Firstly, the fabricated HPGP samples were erected vertically in a prepared device, which included transparent acrylic sheets and light-blocking acrylic sheets (details are given in section Demonstration of the outdoor water-harvesting tests). Placed on the university campus, the samples were shaded with the light-blocking acrylic sheet for three days of continuous moisture sorption. After the sample reached saturation, the water was released using a light-transparent acrylic plate. In the cyclic testing of GO interlayers, the separated GO interlayers are reconstituted into HPGP for further testing. The degraded pectin layer is exposed to soil from the experimental building’s ground floor, and its daily degradation is recorded. Throughout the experiment, moisture sorption, stage-wise water release, and final collected water mass were meticulously documented. Calculated and compared with collection rates in laboratory experiments:
Rc = mc / ma (6)
where Rc denotes the ratio of collected water to adsorbed water, mc denotes the mass of collected water, and ma denotes the mass of adsorbed water.

Theoretical simulation: We used the Amorphous Cell and Forcite plus modules in the Materials Studio 2019 software to simulate the polymer chain. 50 amorphous models, each consisting of four layers of GO interlayers and 150 pectin molecules, were constructed and minimized to obtain the lowest total energy model. Periodic boundary conditions were applied in x, y, and z, and geometry minimization proceeded until the maximum force fell below 1.0×10-4 kcal mol-1 Å-1. We conducted a 300 ps NPT MD simulation to achieve the system's density and equilibrium structure. Prior to NPT, a 300 ps NVT pre-equilibration at 300 K was performed to remove residual stresses.

The COMPASS force field was employed for atomic interactions. Temperature in both NVT and NPT simulations was controlled by a Nosé–Hoover thermostat, and pressure during the NPT stage was maintained by a Berendsen barostat. Short-range nonbonded (van der Waals and real-space electrostatic) interactions were determined using an atom-based method with a cutoff of 16.3 Å, with cubic-spline switching between 14.3 and 16.3 Å; the neighbor list used a 2.0 Å skin and was updated every 10 steps, while long-range electrostatic interactions were calculated using an Ewald sum method with an accuracy of 0.001 and a buffer width of 0.5 Å.

Moisture sorption in HPGP: The sandwich structure was immersed in a pool containing 1110 glycerol molecules to obtain HPGP. The optimized configuration with the lowest total energy was chosen from 50 different configurations. The optimized GO interlayers structure underwent 300 ps of NVT-MD simulation for equilibrium, followed by another 300 ps NPT-MD simulation at 300 K to achieve the actual density. The entire simulation was conducted for 6 ns at 300 K and standard atmospheric pressure. All simulations used the same COMPASS/PBC, cutoff, switching, integrator, and constraint settings as above. Production trajectories were obtained at 300 K and 1 atm, with coordinates saved every 1 ps. To assess reproducibility and quantify uncertainty, n = 5 independent replicas with randomized initial velocities were performed for each condition.

To investigate the diffusion of water molecules in heterogeneous structure and homogeneous structure, we employed packmol and moltemplate for molecular modeling. For heterogeneous structure, we initially constructed a single-layer graphene oxide model with defects using the OPLS force field. OPLS-AA parameters were used for GO and glycerol; water was described by the TIP3P model. Cross-interactions followed Lorentz–Berthelot combining rules. Subsequently, we assembled a thin film comprising 30 layers of defective graphene oxide. We also created water and glycerol models containing 2158 water molecules and 840 glycerol molecules, respectively. Finally, we combined these models to form the heterogeneous structure. The assembled structure was subjected to 100 ps of NVT-MD simulation at 300 K to achieve energy minimization through structural relaxation. An initial semi-isotropic NPT relaxation (100 ps at 300 K, 1 atm) was then applied to release residual in-plane stress before production. For the modeling of homogeneous structure, the mass ratio of graphene oxide to pectin was set at 1:5. Based on this ratio, the molecular counts for graphene oxide, water, and glycerol were determined to be 8, 40, and 840, respectively, in the defective graphene oxide/hydrogel/glycerol model. After assembling the hybrid model, it underwent 100 ps of NVT-MD simulation at 300 K to achieve structural relaxation, resulting in a stable film. Following the completion of the heterogeneous structure and homogeneous structure models, 1 ns of NVT simulation was performed at 300 K to generate full-atom trajectory files and calculate the MSD of water molecules. Diffusion coefficients were extracted from the Einstein relation by linear regression of the mean-squared displacement in the long-time diffusive regime; uncertainties were estimated by bootstrap resampling of non-overlapping trajectory windows within the same 1 ns trajectory and are reported as mean ± 95% confidence interval.

Peer review rounds
[{"round": 1, "reviewer_comments": {"reviewer_1": "This manuscript presents a well-designed and timely study introducing an asymmetric pectin/graphene-oxide organogel (HPGP) for high-yield atmospheric water harvesting. The concept of hydrophilicity asymmetry to decouple condensation and diffusion is compelling and scientifically sound. The work is of clear potential interest to the Nature Communications readership; however, several aspects require further refinement and additional validation before the paper can be considered for publication.\n\nStructural validation\nTo further support the proposed diffusion mechanism, I suggest including one structural scattering experiment (preferably SAXS, though XRD would also be suitable) before and after glycerol infusion and at two relative humidity levels (e.g., 30% and 90%). Reporting the resulting d-spacing and its change would directly link interlayer structure with water-diffusion kinetics.\nIf this measurement is not feasible, Raman spectroscopy (ID/IG ratio) to assess the GO state or AFM/SEM cross-sections to estimate layer thickness could serve as alternative approaches.\n\nBenchmarking and comparative performance\nThe extended tables in the Supporting Information (Tables S2, S4–S6; pp. 26 and 35–43 SI) provide valuable comparative context. To meet the benchmarking standards expected in this field, the main text should explicitly include standardized parameters for each cited reference (relative humidity, temperature, irradiance, and sorbent loading) and moderate the “state-of-the-art” language accordingly (see Fig. 6g, p. 21). This would allow fair comparison under equivalent experimental conditions and avoid potential overstatement of performance advantages.\n\nMechanism and simulations\nThe molecular dynamics simulations (Figs. 10–11, SI pp. 15–16) nicely illustrate diffusion pathways but still lack essential methodological detail, such as the force field used, cutoff parameters, equilibration protocol, and uncertainties in diffusion coefficients. These should be specified. In addition, an experimental validation (e.g., by differential scanning calorimetry (DSC) or NMR to distinguish bound and free water) would provide direct support for the proposed asymmetric diffusion mechanism.\n\nOptimization and reproducibility\nNotes 2 and 4 in the SI justify the selection of four GO layers and explain the structural function of surface wrinkles. This section is scientifically sound, but the reproducibility of sorption/desorption data should be better documented. The authors are encouraged to include replicate numbers or error bars in the main figures to clarify experimental variability.\n\nDurability and environmental stability\nThe only quantitative durability test spans 45 days. Figures 32–33 (pp. 41–42 SI) show mechanical integrity and natural degradation, confirming the material’s biodegradability, yet the long-term environmental stability remains insufficiently characterized. The manuscript should discuss potential degradation under UV exposure, dust accumulation, humidity/temperature cycling, and microbial growth. These factors are critical for evaluating outdoor performance and must be addressed, even qualitatively.\n\nWater quality\nThe FTIR spectra in Fig. 31 (SI p. 40) show no detectable glycerol-related peaks in the condensate, qualitatively supporting the claim that no leaching occurs during water collection. However, this remains a qualitative assessment. To confirm the chemical integrity and environmental safety of the collected water, quantitative compositional analysis is required. Techniques such as LC-MS or GC-MS for potential organic residues and ICP-OES or ICP-MS for trace metals (particularly Zn from the crosslinked pectin) should be used to verify that the condensate contains no detectable contaminants above instrumental detection limits (e.g., < 1 ppm). Such measurements would provide quantitative validation of the material’s stability and strengthen the environmental relevance of the work.\n\nEconomic feasibility and scalability\nThe manuscript does not discuss cost, production feasibility, or material recyclability. Including at least a qualitative analysis (estimating raw material costs, scalability of synthesis, and reuse potential of GO–pectin layers) would add valuable translational insight and contextualize the proposed system within the broader atmospheric water-harvesting landscape.\n\nOverall assessment\nThe study is technically strong and well executed, and the addition of the SI has clarified several aspects of optimization and benchmarking. Nevertheless, the manuscript still lacks quantitative evidence of water purity, long-term environmental durability, and cost feasibility. Addressing these issues and expanding methodological transparency would bring the work in line with Nature Communications standards.", "reviewer_2": "The authors proposed a heterogeneous structure composed of hydrophilic pectin shell and relatively hydrophobic graphene oxide sheets core for hygroscopic polymeric organgel integrated with glycerol. An outdoor experiment was conducted to demonstrate the proposed organogel. Overall, the content is adequate and comprehensive with details provided. However, one issue is that the presentation and writing is somehow not clear enough; another issue is that the outdoor demonstration has some problems that need to be solved. We suggest a major revision before publication.\n\n1. In the last paragraph of the Introduction, please clarify how the GO interlayer amplifies glycerol-generated osmotic pumping as the glycerol appears suddenly from the structure (pectin-GO-pectin). We can tell that glycerin is used from Figure S1, but we cannot get clear information about glycerin in the Introduction, such as where is it, why it is needed, etc. Also, please highlight why the proposed structure can address the research gap mentioned above.\n2. What does the transparent wave shape represent in Figure 1c? Please elaborate and clarify the usage of glycerol and its interactions with pectin and GO. The current description is not clear, for example, “Following glycerol infusion, the GO interlayers effectively minimize interactions between confined water molecules and hydrophilic groups…” Why can glycerol infusion help GO to minimize the interaction? Overall, the description and discussion of glycerol is limited at the beginning of the main text.\n3. In supplemental Note 2, why the surface wrinkles decrease with the number of GO interlayers increase as shown in Figure S35? Also, wrong figure citation of Figure S33 on Page 24.\n4. Wrong figure citation of Figure 3a-d on page 9-10 and no figure citation of 3e. Again, how the GO layer help reduce the interaction between water molecules and hydrophilic groups (pectin)? Where is pectin in Figure 3b and what is the light green region in figure 3c? Brief introduction on homogenous structure is needed. Also, Figures S10 &S11 need clarification.\n5. Will the optimal number of GO interlayers change based on different wrinkles as the surface wrinkles would be kind of random during each sample preparation? In addition, Figure S15 is not properly mentioned and cited in the suitable position in main text. Furthermore, how to guarantee the non-leakage property as shown in Figure S18?\n6. How to define the surface heating and internal heating of GO interlayers in Figure 5c, and how to define the desorption onset in Figure 5f?\n7. The outdoor experiment lasts for 3 days, but the ambient conditions in Figure 6c only shows 1 day. In addition, the daily water productivity various a lot during the 3 days, but no discussion is provided on it; at least the correspond weather conditions or other relevant details should be provided. Also, averaging the 3-day water productivity is not scientific and has no meaning to directly compare with other work.\n8. Why the sorbed mass in outdoor experiment is more than that in laboratory experiment from Figure S30 under the same conditions?", "reviewer_3": "Review:\nThe manuscript (NCOMMS-25-72438-T) presents heterogeneous hygroscopic gels for atmospheric water harvesting with seemingly impressive performance metrics, but there are substantial concerns regarding the novelty of the approach, the robustness of the main conclusions, and the practical scalability of the material. Moreover, significant additional experiments are required to support the authors’ claims. Given the scope of these issues, I recommend rejection in its current form.\n\nDetailed comments:\n1. The concept of using GO and pectin in a layered structure, while interesting, does not represent a significant conceptual leap from existing hygroscopic composites. The authors should provide a more rigorous comparison with previously reported heterogeneous or multi-layered hydrogel/organogel systems (e.g., GO-cellulose, GO-alginate, etc.) to clearly establish the novelty of their design.\n2. The proposed “asymmetric hydrophilicity-driven fast water diffusion” is primarily supported by MD simulations, which are limited in scale and realism. Experimental evidence, such as in-situ Raman or NMR spectroscopy, is needed to directly observe and quantify water transport pathways and dynamics within the heterogeneous structure.\n3. The authors claim that glycerol does not evaporate during solar desorption based on FTIR of evaporated gas. This is insufficient. Long-term cycling tests under realistic outdoor conditions with quantitative analysis of glycerol loss (e.g., via HPLC or GC-MS) are necessary to validate the material's durability.\n4. The water uptake of 0.83 g g⁻¹ at 30% RH is modest and not competitive with state-of-the-art desiccant materials. The authors should compare their material with recent low-RH sorbents (e.g., MOFs, hygroscopic salts, or advanced hydrogels) to better contextualize its performance.\n5. The photothermal conversion efficiency of GO is well-known. The manuscript fails to demonstrate how the HPGP structure enhances this property beyond what is expected from GO alone. Spectral reflectance and thermal imaging under controlled conditions could be provided to substantiate claims of improved light trapping.\n6. The fabrication process involves multiple steps (layer-by-layer assembly, crosslinking, solvent exchange) that are difficult to scale. The authors should discuss the reproducibility of the wrinkle structure, layer uniformity, and the feasibility of mass production.\n7. The outdoor test was conducted only under moderate RH (72–82.6%) and temperature (23–31°C). Performance under extreme conditions (e.g., arid or highly humid climates) is not demonstrated, limiting the generalizability of the conclusions.\n8. While ICP-MS was used to test for metal ions, no analysis was performed on potential organic leachates (e.g., from GO or crosslinkers). Toxicity and biocompatibility assessments are critical for practical applications of harvested water."}, "author_response": "Response to the Reviewers’ Comments\nReviewer #1\nGeneral Comment:\nThis manuscript presents a well-designed and timely study introducing an asymmetric\npectin/graphene-oxide organogel (HPGP) for high-yield atmospheric water harvesting.\nThe concept of hydrophilicity asymmetry to decouple condensation and diffusion is\ncompelling and scientifically sound. The work is of clear potential interest to the Nature\nCommunications readership; however, several aspects require further refinement and\nadditional validation before the paper can be considered for publication.\nOur responses to the comments and suggestions from Reviewer #1\nWe sincerely thank Reviewer #1 for the positive feedback on our work, particularly for\nacknowledging its well-conceived research design and potential appeal to the\nreadership of Nature Communications. We agree that the suggestions regarding\nstructural validation, performance benchmarking, mechanistic simulations,\nreproducibility, durability, water quality, and economic feasibility are crucial for\nenhancing the depth and rigor of our study. According to your meaningful comments,\nthe point-to-point responses according to your kind suggestions have been addressed\nsubstantially in the revised version of our manuscript and are marked by giving the text\na the text\na blue color. We hope our revised version can be accepted by Nature Communications.\nComment 1:\nStructural validation\nTo further support the proposed diffusion mechanism, I suggest including one structural\nscattering experiment (preferably SAXS, though XRD would also be suitable) before\nand after glycerol infusion and at two relative humidity levels (e.g., 30% and 90%).\nReporting the resulting d-spacing and its change would directly link interlayer structure\nwith water-diffusion kinetics. If this measurement is not feasible, Raman spectroscopy\n(I /I ratio) to assess the GO state or AFM/SEM cross-sections to estimate layer\nD G\nthickness could serve as alternative approaches.\nResponse to comment 1:\nWe thank the reviewer for this constructive suggestion. Direct structural\ncharacterization is indeed crucial for empirically linking the GO interlayer structure to\nits hydration state, thereby substantiating our proposed diffusion mechanism.\nAccordingly, we have performed X-ray Diffraction (XRD) analysis as\nsuggested, probing the GO interlayer structure at key stages: its pristine state, after\nglycerol infusion, and following equilibration at 30% and 90% relative humidity (RH),\nas shown in the new Supplementary Fig. 18. The pristine, dried GO film shows a d-\nspacing of 1.13 nm, which serves as a baseline representing the inherent packing of\ndehydrated sheets. Upon infusion with glycerol, the d-spacing significantly increases\nto 1.35 nm. This expansion provides direct evidence that glycerol molecules\nsuccessfully intercalate between the GO sheets, acting as pillars to physically construct\nthe proposed nano-channel network. Subsequently, when the sample was equilibrated\nat 30% RH, the d-spacing further expanded to 1.48 nm. This demonstrates that the\nchannels are hydrophilic and effectively accommodate water molecules, causing the\nstructure to swell. Critically, upon increasing the relative humidity to 90% RH, the d-\nspacing remained unchanged at 1.48 nm. This key finding demonstrates that the\nnano-channel network reaches a saturated and structurally stable hydrated state at\nhigh humidity, forming persistent water transport pathways rather than undergoing\nunlimited swelling or structural collapse. This stable, open channel structure under high\nhumidity provides the requisite physical infrastructure for the rapid water transport\nobserved.\nTo complement the structural data, Raman spectroscopy was employed to assess\nthe structural integrity and defect state of the GO sheets before and after the hydration-\ndehydration cycling (Supplementary Fig. 54). The analysis focuses on the D-band\n(~1350 cm-1), associated with structural defects and disordered carbon, and the G-band\n(~1600 cm-1), corresponding to the in-plane vibration of sp2-hybridized carbon atoms.\nThe intensity ratio of these peaks (I /I ) is a well-established metric for the degree of\nD G\ndisorder. Our measurements show that the I /I ratio remains constant at 0.95 for the\nD G\nGO interlayer both before and after the full hygroscopic cycle. This stability indicates\nthat the process of water sorption and desorption does not introduce additional\nstructural defects or alter the chemical nature of the GO sheets. Taken together, these\nfindings confirm that the GO-glycerol nano-channels are not only structurally stable\nin their dimensions (as shown by XRD) but are also chemically robust (as\nconfirmed by Raman spectroscopy), ensuring their integrity and reusable function as\nefficient water transport pathways.\nSupplementary Fig. 18 XRD patterns of GO interlayers, GO interlayers after glycerol soaking, and\nGO interlayers after moisture sorption at 30% and 90% relative humidity.\nSupplementary Fig. 54 Raman tests of GO interlayers before and after moisture sorption cycles.\nThe changes are highlighted in blue in the revised manuscript.\nIn the Sorption capacity of HPGP section (Page 14, Line 10-15):\n“Subsequently, X-ray Diffraction (XRD) was used to probe the GO interlayer\nstructure (Supplementary Fig. 18). The pristine GO d-spacing of 1.13 nm expanded to\n1.35 nm after glycerol intercalation, confirming the formation of nano-channels. Upon\nhydration, the d-spacing increased to 1.48 nm (at 30% RH) and remained stable at this\nvalue even at 90% RH. This indicates a structurally stable, water-saturated channel\nnetwork at high humidity, which provides the physical conduits for rapid diffusion.”\nIn the Demonstration of the outdoor water-harvesting tests section (Page 23, Line 6-8):\n“Furthermore, Raman spectroscopy confirmed that the I /I ratio remained\nD G\nunchanged after hydration cycles, demonstrating the structural and chemical stability\nof the GO nanosheets throughout the process (Supplementary Fig. 54).”\nComment 2:\nBenchmarking and comparative performance\nThe extended tables in the Supporting Information (Tables S2, S4–S6; pp. 26 and 35–\nexpected in this field, the main text should explicitly include standardized parameters\nfor each cited reference (relative humidity, temperature, irradiance, and sorbent loading)\nand moderate the “state-of-the-art” language accordingly (see Fig. 6g, p. 21). This\nwould allow fair comparison under equivalent experimental conditions and avoid\npotential overstatement of performance advantages.\nResponse to comment 2:\nWe thank the reviewer for their constructive feedback on our comparative analysis. We\nagree that a rigorous comparison demands careful contextualization of our results\nagainst the literature, considering the varying experimental conditions.\nTo address this, we have substantially revised the discussion surrounding our\ncomparative performance figures. In the updated manuscripts, whenever we\nreference data from other studies, we now explicitly state the key experimental\nconditions under which those results were obtained—specifically, the relative humidity,\ntemperature, and where applicable, the solar irradiance. This ensures that any\ncomparison is made with full transparency, allowing the reader to immediately\nunderstand the context. This approach avoids any potential overstatement and provides\na more rigorous, scientifically grounded comparison. Second, we have carefully\nadjusted our wording throughout the manuscript. Descriptive language such as “state-\nof-the-art” has been replaced with more objective, data-driven statements. Finally,\nwe have further refined Tables S2, S5, S6, and S7 in the supporting information. We\nhave worked to ensure that the most detailed experimental parameters available are\nprovided for each cited reference, offering readers a comprehensive basis for\ncomparison.\nThe changes are highlighted in blue in the revised manuscript and supporting\ninformation.\nIn the Introduction section (Page 4, Line 19-21):\n“These features enable a HPGP-based SAWH device to produce up to 2.86\nL kg -1day-1, representing a performance highly competitive with the leading\nwater sorbent\nreported SAWH systems.”\nIn the Sorption capacity of HPGP section (Page 15, Line 14-16):\n“Consequently, HPGP surpasses most previously reported high-performance and\ndifferent structural design sorbent materials in moisture sorption capacity (Fig. 4f,\nSupplementary Figs. 24, 25 and Supplementary Tables. 2, 3)8,10,23–28,19,29–31”\nIn the Demonstration of the outdoor water-harvesting tests section (Page 21, Line 18-\n20):\n“Based on the first-day water production, the sorbent achieved a remarkable\nfreshwater productivity of 2.86 L kg -1day-1, a value that surpasses most leading\nwater sorbent\nsorbents developed for SAWH systems (Fig. 6g and Supplementary Table 7)\n19,27,38,18,39,30,40–42.”\nIn the Conclusion section (Page 25, Line 17-19):\n“These metrics surpass most leading SAWH systems, demonstrating the viability\nof heterogeneous structures for high-efficiency atmospheric water harvesting.”\nSupplementary Table.2 Comparison of water sorption capacity of different sorbent\nmaterials.\nSalt\nSorbent materials Sorption water capacity (RH) &Content Reference\n(%, wt)\nLiCl\nRFMP 2.15–2.68–3.1 g g−1(RH70–80–90%) 19\n(0.2g/mL)\nSMCA 0.5–1–2.5 g g−1 (RH30–60–90%) PPy-Cl 10\nCaCl\nILCA 0.5–1.15–1.5 g g−1 (RH30–60–90%) 2 5\n(25)\nPOG 0.5–2.6–6 g g−1 (RH30–60–90%) Glycerin 1\nLiCl\nCNTs-CILs@cotton rod 0.75–1.2 g g−1 (RH 60–90%) 6\n(30)\nPPy-Cl\nPDA@PP-Cl Hydrogel 0.68–1.61–2.76 g g−1 (RH30–60–90%) 12\n(20)\nPAM–CS–MXene–LiCl LiCl\n0.78–2.32–5 g g−1 (RH30–60–90%) 11\naerogel (4 mol/L)\nPGF 0.64–3.3 g g−1 (RH60–95%) PAAS 8\nLiCl\nBHNC 1.6–2.5–6.2 g g−1 (RH30–60–90%) 20\n(69)\nLiCl\nBilayer scaffold-1.5 0.73–1.32–1.65 g g−1 (RH57–70–95%) 3\n(2)\nLiCl\nAgar /GG/PAM hydrogel 1.623-4.601 g g−1 (RH60–90%) 7\n(3 mol/L)\nLiCl\nTCP-Li 0.90-1.93-3.91 g g−1 (RH30–60–88%) 2\n(35)\nLiCl\nLiCl@MOF-303 0.25-0.4-0.75 g g−1 (RH30–60–80%) 21\n(14.42)\nLiCl\nLiCl@SiO 0.4-0.675 g g−1 (RH30–60%) 22\n2\n(22.5)\nLiCl\nLiCl@Al-fum 0.427-0.829-1.25 g g−1 (RH30–60–80%) 23\n(27.7)\nLiCl\nLiCl@UIO-66 0.595-0.95-1.6 g g−1 (RH30–60–80%) 24\n(30)\nLiCl@MIL- LiCl\n0.3-0.65-0.95 g g−1 (RH30–60–80%) 25\n101(Cr) (33)\nLiCl\nLiCl@ SiO HS 0.7-1.25-2.1 g g−1 (RH30–60–80%) 26\n2\n(39.5)\nLiCl@MIL- LiCl\n0.9-1.6 g g−1 (RH30–60%) 27\n100(Fe) (54.5)\nCoCl\nCo-SHM 0.11–0.83–2.9 g g−1 (RH30–60–90%) 2 28\n(57.1)\nMMPA 0.37-1.07-1.55 g g−1 (RH30–50–90%) MIL-101(Cr) 29\nLiCl@Activated LiCl\n0.15-0.25-0.37 g g−1 (RH30–60–80%) 30\nalumina (AL20) (12.14)\nLiCl\nXD87.50% -PP@LiCl 1.57-3.15 g g−1 (RH30–70%) 31\n(65)\nLiCl\nDBJA 0.74-1.44-3.45 g g−1 (RH30–50–90%) 32\n(52.63)\nLiCl\nTHMPH 1.2-2-5.2 g g−1 (RH30–50–90%) 33\n(50)\nLiCl\nBPLHs 0.91-1.26-1.82 g g−1 (RH30–50–70%) 34\n(34)\nLiCl\nLiCl@CCS aerogels 1.43-2.09-3.21 g g−1 (RH25–50–75%) 35\n(6)\nPNIPAm-co- LiCl\n0.56-1.35-3.78 g g−1 (RH25–50–90%) 36\nPAAS/PANI@LiCl (25)\nLiCl\nSMPH 0.49-0.91-2.98 g g−1 (RH30–50–90%) 37\n(33.56)\nLiCl\nZHPC 0.86-1.5-2.18 g g−1 (RH15–30–60%) 38\n(65)\nLiCl\nZHBC 0.68-1.09-1.67 g g−1 (RH15–30–60%) 38\n(54)\nCS/SA/CMC@MF exh 1.2–2.8–3.9 g g−1 (RH30–60–90%) CS/SA/CMC 39\nMOF-CT/PVA 1.21–2.15–4.44 g g−1 (RH30–60–90%) MOF-CT 40\nLiCl\nCPPY@LiCl 1.64–2.65–4.21 g g−1 (RH30–60–90%) 41\n(85)\nLiCl\nBC/SA/GO-LiCl 1.4–2.53–5.71 g g−1 (RH30–60–90%) 42\n（50）\nLiCl\nNHBA 0.3–2.36 g g−1 (RH35–95%) 43\n（90）\nLiCl\nPCP@LiCl 0.43-0.89-1.48 g g−1 (RH15–30–60%) 44\n（46）\nLiCl\nHIPG 1.01–2.03–6.83 g g−1 (RH30–60–90%) 45\n（54.3）\nLiCl\nLiCl@PAM 1.41-2.46-4 g g−1 (RH30–60–80%) 46\n(50)\nLiCl\nLiCl@ACFF 1.79-2.93 g g−1 (RH30–60%) 47\n（90）\nLiCl\nTOCNF/NaAlg/MOF 303 1.18-4.69 g g−1 (RH30–90%) 48\n（70）\nMTC 0.25–0.45–0.6 g g−1 (RH20–60–80%) MOF-303 49\nCaCl\nCaCl @MIL-101@BC-2 0.78–1.35–2.08 g g−1 (RH30–70–90%) 2 50\n2\n(20)\nLiCl\nPCC20@LiCl- 3 0.99–5.43 g g−1 (RH20–80%) 51\n（3）\nLiCl\nCASN-Li 0.7–0.97–1.5 g g−1 (RH30–60–90%) 52\n（25）\nHPGP (This work) 0.83–2.97–6.57 g g−1(RH30–60–90%) Glycerin\nSupplementary Table.5 Comparison of evaporation rates with different sorbent\nmaterials under 1.0 sun illumination.\nSun\nSorbent materials Evaporation rates (kg m-2 h-1) Reference\nillumination\nCNTs@SiO 1.5\n53\n2.0\n6\nrod\nPDA@PP-Cl\n1.0 sun 1.42\nRFMP 1.75\n1.43\nHPGP (This work) 2.06\nSupplementary Table.6 Summary of water desorption kinetics performance of\nreported sorbent materials in the first 50 min under 1.0 sun illumination.\nSun\nSorbent materials Water desorption ratio (%) Reference\nillumination\nPVA-PAM-LiCl 84\nSupplementary Table.7 Comparison of water harvesting effect of different adsorbent\nmaterials under outdoor conditions.\nWater productivity Relative\nSorbent materials Temperature Reference\n(L -1kg -1d-1) humidity\nwater sorbent\nBHNC 2.82 ~30 °C 60%\n2.57 27-45 °C 35-67%\n7\nhydrogel\nPAMPS-CNT-LiCl\n2.41 ~25 °C 72.3-80.4%\n13\nhydrogel\nLiCl@rGO–SA 2.12 ~30 °C 42-70%\n1.92 27.5-36.5 °C 40-77.5%\nPCLG 0.90 ~30 °C 55-80%\nComment 3:\nMechanism and simulations\nThe molecular dynamics simulations (Figs. 10–11, SI pp. 15–16) nicely illustrate\ndiffusion pathways but still lack essential methodological detail, such as the force field\nused, cutoff parameters, equilibration protocol, and uncertainties in diffusion\ncoefficients. These should be specified. In addition, an experimental validation (e.g., by\ndifferential scanning calorimetry (DSC) or NMR to distinguish bound and free water)\nwould provide direct support for the proposed asymmetric diffusion mechanism.\nResponse to comment 3:\nWe thank the reviewer for their insightful comments, which have prompted us to\nprovide a more detailed account of our simulation methodology and to perform\nadditional experiments for a more robust validation of our proposed mechanism.\n1.Supplementary Content for Molecular Dynamics Simulation\nIn the revised manuscript, we have incorporated a comprehensive description of\nour simulation methodology in the Methods section. Specifically, we now state that the\namorphous GO/pectin cells were built in Materials Studio using the Amorphous Cell\nand Forcite Plus modules. Fifty amorphous models, each comprising four layers of GO\ninterlayers and 150 pectin molecules, were generated and energy-minimized; periodic\nboundary conditions were applied in x, y, and z, and geometry optimization proceeded\nuntil the maximum force was below 1.0×10-4 kcal mol-1 Å-1. To equilibrate these\nsystems, we performed a 300 ps NVT pre-equilibration at 300 K to remove residual\nstresses followed by a 300 ps NPT simulation to reach the system’s density and\nequilibrium structure. All atomic interactions were described with the COMPASS force\nfield; temperature in both NVT and NPT was controlled by a Nosé–Hoover thermostat,\nand pressure in NPT by a Berendsen barostat. Short-range nonbonded (van der Waals\nand real-space electrostatic) interactions were treated with an atom-based method using\na 16.3 Å cutoff and cubic-spline switching between 14.3 and 16.3 Å; the neighbor list\nused a 2.0 Å skin and was updated every 10 steps. Long-range electrostatics were\ncomputed with an Ewald summation (accuracy 0.001; buffer width 0.5 Å). For moisture\nsorption in HPGP, the sandwich structure was immersed in a pool containing 1110\nglycerol molecules to obtain HPGP, and the lowest-total-energy configuration was\nselected from 50 candidates. The optimized GO interlayers structure then underwent\n300 ps of NVT-MD for equilibrium followed by 300 ps of NPT-MD at 300 K to achieve\nthe actual density; the full simulation ran for 6 ns at 300 K and standard atmospheric\npressure. All simulations used the same COMPASS/PBC, cutoff, switching, integrator,\nand constraint settings as above. Diffusion coefficients were obtained from the mean-\nsquared displacement in the long-time diffusive regime, and uncertainties were\nestimated by bootstrap resampling of non-overlapping trajectory windows within the\nsame 1 ns trajectory, reported as mean ± 95% confidence interval. We believe these\nadditions fully address the reviewer’s request for explicit information on force field\nchoice, cutoff parameters, equilibration protocol, and the statistical treatment of\ndiffusion coefficients.\n2. Direct Experimental Evidence for the Asymmetric Diffusion Mechanism from\nLF-NMR\nTo experimentally validate the asymmetric diffusion mechanism predicted by our\nmolecular dynamics simulations, we have conducted low-field nuclear magnetic\nresonance (LF-NMR) T relaxation experiments. This technology non-destructively\n2\ndifferentiates water populations based on molecular mobility, classifying them\n them\naccording to their relaxation times: 0.1–10 ms for bound water, 10–100 ms for\nintermediate water, and >100 ms for free water (Fig.R1). We analyzed three key sample\ngroups: the HPGP at different hydration levels (initial, 30% RH, and 90% RH), and two\ncontrol samples—pure glycerol-intercalated pectin and pure glycerol-intercalated\nGO—both analyzed at initial and 90% RH conditions.\nFig.R1 The distribution of water molecules among the states of bound, intermediate, and free water\nmolecules of hydrogel.\nThe results, as detailed below and shown in the T relaxation spectra\n2\n(Supplementary Fig. 13), provide direct and compelling experimental support for our\nproposed mechanism.\n1) HPGP (Heterogeneous Structure) Confirms the Multi-State Water Sorption\nProcess (Supplementary Fig. 13d)\nAt 30% RH, the T spectrum of HPGP is dominated by peaks at very short\n2\nrelaxation times (<10 ms). This is the classic signature of bound water, confirming our\nhypothesis that initial water uptake involves strong immobilization via hydrogen\nbonding within the highly hydrophilic pectin layers.\nAt 90% RH, a dramatic change is observed. While the bound water peaks remain,\na new, distinct, and substantial peak emerges at a much longer T relaxation time (>100\n2\nms). This peak is the unambiguous signature of free water. This directly demonstrates\nthat once the primary binding sites in the pectin are saturated, excess water transitions\ninto a high-mobility state, which, according to our model, resides within the GO\ninterlayer channels. This two-stage appearance of distinct water populations strongly\nsupports the proposed decoupling of water capture (binding) and transport (free).\n2) Control Experiments Clarify the Roles of Pectin and GO (Supplementary Fig.\n13a, b)\nTo further prove the spatial decoupling of these functions, we analyzed the\ncomponents separately:\nGlycerol-Pectin: The Glycerol-Pectin matrix already displays a prominent T\n2\npeak in the intermediate range (10–100 ms). This signal is primarily attributed to the\nliquid glycerol itself, which is intercalated within the pectin network, forming a baseline\nfluidic system. Upon hydration to 90% RH, a critical phenomenon is observed. Instead\nof creating a more mobile phase, the influx of water molecules forms strong hydrogen\nbonds with both pectin and glycerol, creating a highly viscous ternary hydrogel. This is\nevidenced by the fact that the T peak does not shift to longer times; instead, it remains\n2\nwithin the intermediate range, signifying that the overall molecular mobility is severely\nrestricted by the swollen polymer network. This result demonstrates the inherent\nlimitation of a purely hygroscopic polymer system: while it has high capacity, it traps\nwater in a high-viscosity, gel-like state, thus impeding rapid transport.\nGlycerol-GO Interlayers: In stark contrast, the hydrated GO-only sample’s\nsignal is centered primarily in the intermediate range but with limited free water\ncharacter, indicating that atmospheric moisture merely wets the graphene surfaces\nwithout filling the nanocapillaries to a bulk state. This proves that without the pump\neffect of the pectin reservoir, the GO channels cannot achieve their full transport\npotential.\n3) Dynamic Water Exchange Validates Interconnectivity\nAn even more subtle but powerful piece of evidence comes from the evolution of\nthe bound water peaks. As the system hydrates from 30% to 90% RH, the peak\ncorresponding to weakly bound water (~10 ms) in HPGP actually decreases in\namplitude, while the free water peak grows enormously. This phenomenon is a hallmark\nof dynamic exchange between water populations. It indicates that the bound water in\nthe pectin layers is not isolated but is in rapid exchange with the free water in the GO\nchannels. This confirms the seamless and efficient transfer of water from the capture\nsites to the transport network, which forms the basis of our asymmetric diffusion\nmechanism.\nIn summary, the LF-NMR results provide a multi-faceted experimental validation\nof our proposed mechanism. They not only distinguish and quantify the existence of\nboth bound and free water but also, through the analysis of the complete HPGP and its\nindividual components, spatially assign the roles of water capture to the pectin shell\nand rapid transport to the GO interlayers. The evidence of dynamic exchange further\nconfirms the efficient coupling between these two functions. This body of experimental\ndata is in excellent agreement with our simulation results and supports the central\nclaims of our manuscript.\nBy integrating our computational and experimental findings, we can draw a\ncohesive and strongly supported conclusion. The LF-NMR results provide direct\nexperimental proof of the existence of two distinct water populations—bound and\nfree—within the HPGP material, with the free water population emerging at high\nhydration levels. This aligns perfectly with the insights from our MD simulations. As\nstated in the manuscript: “Our analysis (Fig. 3d, e and Supplementary Fig. 12) shows\nthat the diffusion coefficient D of water molecules in heterogeneous structure is\napproximately 204.03, significantly higher than that in homogeneous structure (around\n181.16).” The high-velocity diffusion pathway predicted by the simulations is the\nmicroscopic origin of the highly mobile free water population detected by LF-NMR.\nThus, the synergy between direct experimental observation and atomistic simulation\nprovides compelling validation for the asymmetric hydrophilicity-driven decoupling\ndesign. The LF-NMR data confirms what is happening (the existence of two water\nstates), while the MD simulations explain why it is happening (the creation of low-\nfriction GO nanochannels). This combined evidence provides strong support for our\nhypothesis that the spatial decoupling of water capture (bound water in pectin) and\ntransport (free water in GO) effectively mitigates the inherent trade-off between\nsorption capacity and diffusion kinetics in hygroscopic materials.\nSupplementary Fig. 13 a, Low-field NMR tests of Glycerol-Pectin under different hydration levels\n(original and 90% RH). b, Low-field NMR tests of Glycerol-GO interlayers under different\nhydration levels (original and 90% RH). c, Low-field NMR tests of HPGP under different hydration\nlevels (original, 30% RH, and 90% RH). d, Low-field NMR tests of HPGP, Glycerol-Pectin and\nGlycerol-GO interlayers under 90% RH.\nFig. 3 Mechanism for continuous and high-capacity moisture sorption of the HPGP. a, i. Glycerol\nmolecules carry water molecules into the HPGP interior using osmotic pressure. ii. Water molecules\nreplace glycerol molecules bound to the GO interlayers in the form of hydrogen bonds, completing\nthe fixation of water molecules on the GO interlayers. b, The migration of water molecules within\nheterogeneous structure. c, The migration of water molecules within homogeneous structure. d, The\nMSD-t curve of water molecule migration in heterogeneous structure. e, The MSD-t curve of water\nmolecule migration in homogeneous structure. f, Low-field NMR tests of HPGP under different\nhydration levels (original, 30% RH, and 90% RH).\nThe changes are highlighted in blue in the revised manuscript and supporting\ninformation.\nIn the Theoretical simulation section (Page 29,30,31):\n“We used the Amorphous Cell and Forcite plus modules in the Materials Studio\nsoftware to simulate the polymer chain. 50 amorphous models, each consisting of four\nlayers of GO interlayers and 150 pectin molecules, were constructed and minimized to\nobtain the lowest total energy model. Periodic boundary conditions were applied in x,\ny, and z, and geometry minimization proceeded until the maximum force fell below\n1.0×10-4 kcal mol-1 Å-1. We conducted a 300 ps NPT MD simulation to achieve the\nsystem’s density and equilibrium structure. Prior to NPT, a 300 ps NVT pre-\nequilibration at 300 K was performed to remove residual stresses.\nThe COMPASS force field was employed for atomic interactions. Temperature in\nboth NVT and NPT simulations was controlled by a Nosé–Hoover thermostat, and\npressure during the NPT stage was maintained by a Berendsen barostat. Short-range\nnonbonded (van der Waals and real-space electrostatic) interactions were determined\nusing an atom-based method with a cutoff of 16.3 Å, with cubic-spline switching\nbetween 14.3 and 16.3 Å; the neighbor list used a 2.0 Å skin and was updated every 10\nsteps, while long-range electrostatic interactions were calculated using an Ewald sum\nmethod with an accuracy of 0.001 and a buffer width of 0.5 Å.\nMoisture sorption in HPGP: The sandwich structure was immersed in a pool\ncontaining 1110 glycerol molecules to obtain HPGP. The optimized configuration with\nthe lowest total energy was chosen from 50 different configurations. The optimized GO\ninterlayers structure underwent 300 ps of NVT-MD simulation for equilibrium,\nfollowed by another 300 ps NPT-MD simulation at 300 K to achieve the actual density.\nThe entire simulation was conducted for 6 ns at 300 K and standard atmospheric\npressure. All simulations used the same COMPASS/PBC, cutoff, switching, integrator,\nand constraint settings as above. Production trajectories were obtained at 300 K and 1\natm, with coordinates saved every 1 ps. To assess reproducibility and quantify\nuncertainty, n = 5 independent replicas with randomized initial velocities were\nperformed for each condition.\nTo investigate the diffusion of water molecules in heterogeneous structure and\nhomogeneous structure, we employed packmol and moltemplate for molecular\nmodeling. For heterogeneous structure, we initially constructed a single-layer graphene\noxide model with defects using the OPLS force field. OPLS-AA parameters were used\nfor GO and glycerol; water was described by the TIP3P model. Cross-interactions\nfollowed Lorentz–Berthelot combining rules. Subsequently, we assembled a thin film\ncomprising 30 layers of defective graphene oxide. We also created water and glycerol\nmodels containing 2158 water molecules and 840 glycerol molecules, respectively.\nFinally, we combined these models to form the heterogeneous structure. The assembled\nstructure was subjected to 100 ps of NVT-MD simulation at 300 K to achieve energy\nminimization through structural relaxation. An initial semi-isotropic NPT relaxation\n(100 ps at 300 K, 1 atm) was then applied to release residual in-plane stress before\nproduction. For the modeling of homogeneous structure, the mass ratio of graphene\noxide to pectin was set at 1:5. Based on this ratio, the molecular counts for graphene\noxide, water, and glycerol were determined to be 8, 40, and 840, respectively, in the\ndefective graphene oxide/hydrogel/glycerol model. After assembling the hybrid model,\nit underwent 100 ps of NVT-MD simulation at 300 K to achieve structural relaxation,\nresulting in a stable film. Following the completion of the heterogeneous structure and\nhomogeneous structure models, 1 ns of NVT simulation was performed at 300 K to\ngenerate full-atom trajectory files and calculate the MSD of water molecules. Diffusion\ncoefficients were extracted from the Einstein relation by linear regression of the mean-\nsquared displacement in the long-time diffusive regime; uncertainties were estimated\nby bootstrap resampling of non-overlapping trajectory windows within the same 1 ns\ntrajectory and are reported as mean ± 95% confidence interval.”\nIn the Mechanism for continuous and high-capacity moisture sorption of the HPGP\nsection (Page 10,11, Line 19-23, 1-9):\n“To experimentally validate this simulation-predicted high-mobility state, LF-\nNMR measurements were performed. The results reveal a critical humidity-dependent\ntransition facilitated by this specific structure (Fig. 3f). At low humidity (30% RH), the\nspectrum is dominated by bound and intermediate water signals, confirming the role of\nthe outer pectin layers in initially capturing atmospheric moisture. Strikingly, at 90%\nRH, a distinct and substantial population of free water (>100 ms) emerges. This\nbehavior contrasts sharply with the control experiments on individual components\n(Supplementary Note 2 and Supplementary Fig. 13). While pure pectin primarily\nconstrains water within the intermediate range and pure GO exhibits signals\ncharacteristic of surface-interacting water, the HPGP demonstrates a clear structural\nsynergy. The hygroscopic pectin coating acts as a saturated reservoir, effectively\npumping captured moisture into the GO interlayers. This ensures the graphene\nnanocapillaries are fully flooded, allowing water to transition from a surface-bound\nstate to a highly mobile, bulk-like fluid state. This direct observation confirms that the\n\nheterogeneous structure not only captures water but effectively activates high-speed\ntransport channels.”\nIn the supporting information:\n“Note 2: To elucidate the molecular-level water transport mechanism within the\nHPGP structure, we employed low-field nuclear magnetic resonance (LF-NMR)\nrelaxometry, which probes the mobility of water protons via their transverse relaxation\ntime (T ). Shorter T values (<10 ms) correspond to motion-restricted bound water,\n2 2\nwhile longer values (>100 ms) signify highly mobile free water. We first established\nbaseline assignments using control experiments on the individual components (Fig.13).\nWe first established baseline assignments using control experiments (Fig.13a). The\nGlycerol-Pectin matrix already displays a prominent T peak in the intermediate range\n2\n(10–100 ms). This signal is primarily attributed to the liquid glycerol itself, which is\nintercalated within the pectin network, forming a baseline fluidic system. Upon\nhydration to 90% RH, a critical phenomenon is observed. Instead of creating a more\nmobile phase, the influx of water molecules forms strong hydrogen bonds with both\npectin and glycerol, creating a highly viscous ternary hydrogel. This is evidenced by\nthe fact that the T peak does not shift to longer times; instead, it remains within the\n2\nintermediate range, signifying that the overall molecular mobility is severely restricted\nby the swollen polymer network. This result powerfully demonstrates the inherent\nlimitation of a purely hygroscopic polymer system: while it has high capacity, it traps\nwater in a high-viscosity, gel-like state, thus impeding rapid transport.\nConversely, Glycerol-GO interlayers also exhibit a signal centered primarily in the\nintermediate range but with lower amplitude and limited free water character. This\nindicates that without the driving force of an external reservoir, atmospheric moisture\nmerely wets the graphene surfaces and forms hydration layers, without filling the\nnanocapillaries to a bulk state.\nBuilding on these baselines, the HPGP structure reveals a transformative synergy.\nAt low humidity (30% RH), the spectrum resembles the pectin control, confirming\ninitial uptake is driven by the coating. However, at 90% RH, a dramatic evolution\noccurs. A distinct, high-amplitude free water peak (>100 ms) emerges, which is\nphysically distinct from the constrained “swollen water” observed in the pure pectin\ncontrol. This implies a reservoir-to-channel mechanism: the pectin layer captures\nmoisture into its hydrogel network, but instead of stagnating in this restricted state, the\nwater is effectively pumped into the low-friction GO interlayers (Fig.13c). This\ntransition converts semi-constrained moisture into a high-speed, bulk-like fluid,\nvalidating the asymmetric diffusion mechanism proposed in our simulations.”\nComment 4:\nOptimization and reproducibility\nNotes 2 and 4 in the SI justify the selection of four GO layers and explain the structural\nfunction of surface wrinkles. This section is scientifically sound, but the reproducibility\nof sorption/desorption data should be better documented. The authors are encouraged\nto include replicate numbers or error bars in the main figures to clarify experimental\nvariability.\nResponse to comment 4:\nWe thank the reviewer for emphasizing the need to document experimental\nreproducibility. To address this, we have systematically incorporated error bars,\nderived from replicate experiments, into all figures presenting sorption/desorption performance.\nThis includes key figures for equilibrium uptake comparison and sorption kinetics,\nthereby providing a clear, quantitative representation of the data’s variability and\nrobustness. These error bars represent the standard deviation calculated from at least\nfive independent experiments. Accordingly, we have also updated the corresponding\nfigure captions to explicitly state the number of replicates (e.g, “Data are presented as\nthe mean ± standard deviation from five independent experiments.”). These additions\ndemonstrate the consistency and low variability of our experimental results, providing\nstrong evidence for the reliability of our material’s performance.\nThe changes are highlighted in blue in the revised manuscript (Page 16,20, Line\n5-6, 10-11).\nFig. 4 High sorption capacity of HPGP for high-yield water harvesting. a, Comparison of water\nsorption capacity between heterogeneous and homogeneous structure at 25 °C, 90% RH. b, The\ntrend of moisture sorption variation in GO interlayers with different numbers of layers after being\nsoaked in glycerin. c, The influence of pectin layer on the moisture sorption of HPGP at different\nthicknesses. Data are presented as the mean ± standard deviation from five independent experiments.\nd, Variation of HPGP moisture sorption with the number of GO interlayers and pectin layer\nthickness. e, Normalised sorption ratios (M\nt\n/M\ne\n) are plotted as a function of t1/2 based on the mass\nof water sorbed, where the spheres represent the experimental data and the lines are the data fitted\nby Fick’s second law. f, Comparison of moisture sorption capacity of different sorbent materials1–\n12.\nFig. R2 Correction in supporting information.\nFig. 5 Solar-driven water desorption performance of HPGP. a, UV-Vis-NIR absorption\ncharacteristics of GO interlayers, pectin, and HPGP. The yellow shadow signifies solar irradiance,\nweighted by the AM 1.5 G standard solar spectrum. b, Surface temperature variations of GO\ninterlayers, pectin, and HPGP under 1.0 sun illumination. c, Surface temperature variations of fully\nhydrated HPGP under different solar illumination. d, The dispersion of the heat transfer medium\nand the heat transfer modes in heterogeneous structure and homogeneous structure. e, Surface\ntemperature and average mass variations of heterogeneous structure and homogeneous structure\nunder 1.0 sun illumination. Data are presented as the mean ± standard deviation from five\nindependent experiments. f, Variation in the average mass of fully hydrated HPGP under different\nsolar illumination. g, The D values of heterogeneous structure and homogeneous structure at the\nwd\nsolar illuminations of 0.7, 1.0, 1.3, and 1.6 suns, respectively. h, Comparison of evaporation rates\nwith different sorbent materials under 1.0 sun illumination1,3,5,6,10,12,4,55,53,54.\nIn the Methods section (Page 28, Line 10-11, 19-20):\n“Each test included five sets of samples, and the average values were calculated\nfor statistics.”\nComment 5:\nDurability and environmental stability\nThe only quantitative durability test spans 45 days. Figures 32–33 (pp. 41–42 SI) show\nmechanical integrity and natural degradation, confirming the material’s\nbiodegradability, yet the long-term environmental stability remains insufficiently\ncharacterized. The manuscript should discuss potential degradation under UV exposure,\ndust accumulation, humidity/temperature cycling, and microbial growth. These factors\nare critical for evaluating outdoor performance and must be addressed, even\nqualitatively.\nResponse to comment 5:\nWe thank the reviewer for emphasizing the importance of long-term environmental\nstability, a crucial aspect for real-world applications. To bridge this gap, we have\nconducted a series of targeted experiments to systematically evaluate the durability of\nour pectin hydrogel under simulated and real-world outdoor conditions, focusing\nspecifically on UV exposure, temperature/humidity cycling, dust accumulation, and\nmicrobial growth.\nStability under different environments (UV, temperature/humidity cycling,\nand dust): To evaluate the durability of the pectin hydrogel under different\nenvironment, we conducted a series of accelerated aging tests. One set of samples was\nsubjected to continuous Ultraviolet light irradiation (365 nm) for 168 hours (7 days) to\nsimulate prolonged sun exposure. A second set underwent seven cycles of sharp\ntemperature and humidity fluctuations, alternating between 25 °C/90% RH and\n30 °C/30% RH, to mimic diurnal environmental shifts. A third set was artificially\ntreated with dust to assess its resilience to particulate accumulation. Following these\ntreatments, all samples were weighed, and their mass remained remarkably stable, with\nnegligible variations within ±0.0005 g of their initial weight. Furthermore, macroscopic\nexamination confirmed that the hydrogels retained their structural integrity and original\nmorphology, as visually documented in Supplementary Fig. 55. These results\ncollectively demonstrate the material’s excellent stability against common abiotic\ndegradation factors encountered in outdoor applications.\nSupplementary Fig. 55 a. Outdoor stability test of the pectin layer after dust adhesion on its surface\nb. Stability test of the pectin layer after cycling between 25 °C/90% RH and 30 °C/30% RH. c.\nOutdoor stability test of the pectin layer under UV irradiation. d. Degradation test of the pectin layer\nin soil.\nResistance to Microbial Growth during Operation: To assess the potential for\nmicrobial degradation during atmospheric water harvesting, we analyzed the diversity\nof microbial colonies on the hydrogel samples before and after the aforementioned\nstress tests. As shown in Supplementary Fig. 56a and Table. 8, the material\nexhibited exceptional resistance. Under UV exposure conditions, no microbial\ncolonies were detected (0 colony types), likely due to the sterilizing effect of the\nradiation. Even under conditions prone to contamination, such as\ntemperature/humidity cycling and dust exposure, microbial growth was minimal,\nwith only 4 distinct colony types identified in each scenario. This low count indicates\nthat our pectin hydrogel possesses excellent resistance to airborne microbial\ncolonization and degradation under typical operational conditions, ensuring its stability\nand hygiene during use.\nBiodegradability in Soil Environment: While demonstrating operational\nstability, we also re-confirmed the material’s intended biodegradability as an eco-\nfriendly feature. To create a clear comparison, we placed a separate set of hydrogel\nsamples in a soil environment. In stark contrast to the operational tests, the soil\nsamples were rapidly colonized. As shown in the time-dependent analysis\n(Supplementary Fig. 56b), the number of distinct colony types found on the\nhydrogel in soil reached 34, significantly higher than the 0-4 types observed in\noperational environments. Furthermore, analysis of colony types and content\n(Supplementary Fig. 56c) identified these dominant decomposers, including\nspecific fungal species such as Monographella, Botrytis, and Scedosporium. This\ncontrolled experiment effectively decouples operational stability from end-of-life\nbiodegradability. It proves that our material is robust enough for its intended application\n(resisting airborne microbes) but will effectively decompose through the action of\nspecific soil microorganisms when disposed of, thus preventing long-term waste\naccumulation.\nSupplementary Fig. 56 a, Changes in Microbial Colony Types Before and After a Seven-Day\nExposure to Three Conditions: UV, Cycling, and Dust exposure. b, Types and Abundance of\nMicrobial Colonies in Soil. c, Colony growth on the pectin layer buried in soil was monitored over\na 12-hour period. After 10 hours, the colony types observed on the layer became identical to those\nfound in the surrounding soil.\nSupplementary Table. 8 Specific Microbial Colony Types Identified on the Pectin\nLayer After Exposure to Different Environments.\nDifferent Colony Types Colony Types\nColony Name\nEnvironments (Before) (After)\nUV 0 0 N/A\nGram-positive bacilli\nStreptococcus flora\nCycling 0 4\nMycobacteria\nEscherichia coli\nGram-positive bacilli\nStreptococcus flora\nDust exposure 0 4\nMycobacteria\nEscherichia coli\nThe changes are highlighted in blue in the revised manuscript and Supporting\ninformation.\nIn the Demonstration of the outdoor water-harvesting tests section (Page 23, Line 8-\n15):\n“To validate outdoor applicability, HPGP was subjected to rigorous environmental\ntesting. The pectin layer exhibited exceptional stability, maintaining structural integrity\nand resisting airborne microbial adhesion under UV irradiation, temperature and\nhumidity cycling, and dust exposure, with colony analysis revealing negligible\nmicrobial colonization during simulated operation (Supplementary Fig. 55 and\nSupplementary Note 8). This operational durability complements the biodegradability\nof pectin layer: in contrast to the surface during use, soil-buried samples were rapidly\ndecomposed by diverse microorganisms, mitigating environmental pollution\n(Supplementary Fig. 56 and Supplementary Table 8).”\nIn the Supporting information section:\n“Note 8: To simulate long-term outdoor usage, HPGP samples were subjected to\nthree conditions: (1) Continuous UV irradiation (365 nm) for 168 hours; (2) Seven\ncycles of rapid temperature/humidity shifts (25 °C/90% RH to 30 °C/30% RH); and (3)\nArtificial dust accumulation.\nPhysical Stability: Gravimetric analysis post-treatment showed negligible mass\nvariation (< ±0.0005 g), confirming excellent resistance to abiotic degradation.\nMicrobiological Stability: We further conducted high-throughput sequencing to\nprofile the microbial communities on the sample surfaces. As shown in Fig.56, the\nmaterial demonstrated strong resistance to airborne colonization. No microbial species\n(0) were detected in the UV-exposed group, and only a minimal diversity of 4 species\nwas found in the Cycling and Dust groups.\nBiodegradability Validation: To verify end-of-life degradability, samples were\nburied in natural soil. In contrast to the airborne groups, soil-buried samples showed a\nrich microbial colonization with 34 distinct species identified, dominated by\ndecomposers such as Monographella, Botrytis, and Scedosporium. This stark\ndifference in species richness (4 in air and 34 in soil) confirms that the pectin layer is\nengineered to remain stable and hygienic during operation while ensuring efficient\nbiodegradation upon disposal.”\nComment 6:\nWater quality\nThe FTIR spectra in Fig. 31 (SI p. 40) show no detectable glycerol-related peaks in the\ncondensate, qualitatively supporting the claim that no leaching occurs during water\ncollection. However, this remains a qualitative assessment. To confirm the chemical\nintegrity and environmental safety of the collected water, quantitative compositional\nanalysis is required. Techniques such as LC-MS or GC-MS for potential organic\nresidues and ICP-OES or ICP-MS for trace metals (particularly Zn from the crosslinked\npectin) should be used to verify that the condensate contains no detectable contaminants\nabove instrumental detection limits (e.g., < 1 ppm). Such measurements would provide\nquantitative validation of the material’s stability and strengthen the environmental\nrelevance of the work.\nResponse to comment 6:\nWe thank the reviewer for their insightful feedback on water quality. We agree that\nquantitative analysis is essential for a robust assessment of the system’s safety and\npractical viability. Accordingly, we have conducted a series of targeted analyses on the\ncollected water to provide this crucial data. The analysis includes GC-MS to detect\npotential organic pollutants, ICP-MS to measure the concentration of key metal ions,\nand Total Organic Carbon (TOC) analysis to represent the total amount of organic\nmatter. The GC-MS results show no characteristic peaks corresponding to glycerol\nor its thermal decomposition products. The main components detected were residual\natmospheric gases such as oxygen and carbon monoxide (Supplementary Figs. 48-50).\nSimilarly, the ICP-MS test indicated that the concentrations of various key metal ions,\nparticularly zinc (Zn2+) used for cross-linking, were far below the safe drinking\nwater standards set by the World Health Organization (WHO). Finally, the TOC level\nin the collected water was found to be exceptionally low (<5 mg/L), which is\ncomparable to that of deionized water and further confirms the absence of leached\norganic matter (Fig. 6e).\nThe glycerol is securely immobilized within the HPGP material through both\nhydrogen bonding and chemical crosslinking. This robust immobilization prevents it\nfrom being carried over with water vapor during desorption, even across multiple\nsorption-desorption cycles. Similarly, the chemically crosslinked zinc ions remain\nstably fixed at the network nodes and do not leach into the collected water. To enhance\nthe rigor and completeness of the manuscript, we will explicitly analyze the data\nobtained from GC-MS, ICP-MS, and TOC data in the main manuscripts, thereby\nproviding authoritative quantitative support for the environmental safety of the\nmaterials and the purity of the produced water.\nThe changes are highlighted in blue in the revised manuscript and supporting\ninformation.\nIn the Demonstration of the outdoor water-harvesting tests section (Page 22, Line 9-\n20):\n“The stability of internal glycerol and the purity of the desorption process were\nrigorously investigated. Analysis of the vapor phase via Fourier-transform infrared\nspectroscopy (FTIR) confirmed the absence of evaporated glycerol; specifically, while\nstrong absorption peaks corresponding to the O-H bonds of water were observed (3300–\n3800 cm-1), the characteristic C-H absorption peaks of glycerol (2500–3000 cm-1) were\nundetectable (Supplementary Fig. 47). This was further corroborated by gas\nchromatography-mass spectrometry (GC-MS), which revealed no molecular glycerol\nor its thermal decomposition byproducts in the gas phase, only residual atmospheric\ncomponents (Supplementary Figs. 48-50). Consequently, the harvested water exhibited\nexceptional purity. Its total organic carbon (TOC) level was minimal (<5 mg/L), on par\nwith deionized water, confirming no organic leaching. Moreover, inductively coupled\nplasma mass spectrometry (ICP-MS) analysis showed no zinc ion leakage and verified\nthat the water quality complies with World Health Organization (WHO) standards (Fig.\n6e).”\nSupplementary Fig. 48 Chromatogram of the collected water.\nSupplementary Fig. 49 Chromatogram of the collected water.\nSupplementary Fig. 50 Chromatogram of the collected water.\nFig. 6e Quality of collected water compared to the WHO standard.\nComment 7:\nEconomic feasibility and scalability\nThe manuscript does not discuss cost, production feasibility, or material recyclability.\nIncluding at least a qualitative analysis (estimating raw material costs, scalability of\nsynthesis, and reuse potential of GO–pectin layers) would add valuable translational\ninsight and contextualize the proposed system within the broader atmospheric water-\nharvesting landscape.\nResponse to comment 7:\nWe sincerely thank the reviewer for this insightful and crucial comment. The practical\nviability of any new material for atmospheric water harvesting is indeed contingent\nupon its economic feasibility, production scalability, and long-term sustainability. We\nacknowledge that our original manuscript did not adequately address these aspects. To\naddress this issue, we have added a new paragraph in the “Demonstration of the outdoor\nwater-harvesting tests” section regarding future prospects, specifically to discuss these\nproblems.\nBelow, we have conducted a detailed analysis from the three perspectives\nmentioned by the reviewer to ensure that the proposed system is placed within the\nbroader landscape of atmospheric water harvesting.\n1. Cost-Effectiveness of Raw Materials\nA key advantage of our HPGP organogel lies in the intrinsic low cost and wide\navailability of its primary components.\nPectin, the outer shell in this system, is a natural polysaccharide extracted\ncommercially from citrus peels and apple pomace, which are abundant byproducts of\nthe food processing industry. Its current market price is relatively low (typically in the\nrange of $15-30 per kilogram for industrial grades), making it a highly cost-effective\nsubstrate for large-scale applications. Its food-grade status also ensures its inherent\nsafety and biocompatibility (Fig. R3). [1]\nFig. R3 The Wide-Ranging Sources and Applications of Pectin. [2]\nGraphene Oxide, the intermediate layer in this system, while research-grade GO\ncan be expensive, the cost for industrial-scale production has plummeted in recent years.\nGO is synthesized from natural graphite, a globally abundant and inexpensive carbon\nsource. The modified Hummers method, which we employed, is the most common and\nscalable process for graphite oxidation. With process optimization and economies of\nscale, the production cost of GO is projected to fall significantly, making it a viable\ncomponent for bulk materials like ours. [3] Glycerol, the liquid phase entity in the\nsystem, as a major byproduct of the biodiesel industry, crude glycerol is inexpensive\nand globally oversupplied. While purification adds cost, industrial-grade glycerol\nremains a very affordable liquid sorbent. [4]\nThe reliance on earth-abundant, industry-byproduct, or natural raw materials\npositions the HPGP system as a fundamentally low-cost technology, which is a critical\nprerequisite for its deployment, especially in resource-limited regions.\n2. Production Scalability\nFirst, concerning the reproducibility of the crucial wrinkle structure, we can\nconfirm its high consistency over extended periods. The formation of these wrinkles is\ngoverned by a well-understood physical mechanism: strain mismatch arising from the\niterative drying and differential shrinkage of the GO layers. The primary determinants\nof the wrinkle wavelength and amplitude are the material’s modulus and the final dry\nfilm thickness, which are directly controlled by the GO solution concentration and the\nnumber of deposition-drying cycles. Systematic experiments show that a four-layer\nstructure consistently forms the optimal wrinkle pattern. This conclusion is supported\nby the macroscopic images of samples prepared at different times from December 2022\nto the present, all of which exhibit a consistent wrinkle pattern (Supplementary Fig. 58).\nSimilarly, regarding layer uniformity, we have conducted rigorous quality control\nthroughout our research. Thickness measurements of the GO base films, also performed\non samples from different batches over the same extended timeframe, confirm excellent\nuniformity with minimal deviation (Supplementary Fig. 59). This consistency\nunderscores the robustness of our layer-by-layer assembly protocol, where controlled\nsolution spreading and drying steps ensure a uniform deposition process.\nSupplementary Fig. 58 From December 2022 to December 2025, the GO film has a stable wrinkle\nstructure.\nSupplementary Fig. 59 The GO film from December 2022 to December 2025 has a uniform\nthickness.\nFinally, we have carefully considered the feasibility of mass production and\nenvision a clear pathway to translate our laboratory-scale “spread-dry-repeat” method\ninto an industrially relevant, continuous process (Supplementary Fig. 57). The four-\nlayer GO base film can be formed using established techniques such as spray/blade\ncoating or slot-die coating, coupled with a multi-zone hot-air drying system to perform\nthe iterative deposition cycles. Following the formation of the base film, the surface\npectin layers would be applied to both sides using a similar coating process.\nSubsequently, the functionalization steps can be adapted to an in-line configuration: the\ncross-linking would occur in a short-residence-time anhydrous zinc acetate bath, and\nthe final glycerol solvent exchange could be managed in a counter-current washing\ncascade to enhance throughput and reduce solvent consumption.\nIt is important to highlight that all the aforementioned steps—coating, multi-zone\ndrying, and immersion baths—are standard unit operations within the membrane and\ncoating industries. Key process parameters such as coating speed, drying temperature\nand humidity, and residence time can be precisely controlled to replicate the thermal\nhistory and layering effect achieved in our lab. Given that our entire process utilizes\naqueous solutions, operates at ambient or mild temperatures, and requires no high-\nvacuum or cleanroom facilities, we are confident that scaling this fabrication from\ncentimeter-sized lab samples to meter-scale roll-to-roll production is engineeringly\nfeasible. While we refrain from adding new scale-up data in the current manuscript to\nmaintain focus, we have supplemented the methods section with more explicit process\nparameters and quality control metrics. This will ensure that our peers can readily\nreplicate the material’s unique morphology and high performance under equivalent\nconditions.\nSupplementary Fig. 57 Simulated large-scale factory preparation process for HPGP.\n3. Material Recyclability and Sustainability\nThe unique heterogeneous design of our HPGP not only enhances performance but\nalso offers significant advantages in terms of sustainability and end-of-life management.\nMechanical Disassembly: As demonstrated in Supplementary Fig. 51, the HPGP\nstructure is not permanently bonded and can be mechanically delaminated. This\nphysical separation is a crucial feature for recycling. After a long service life, the\nmaterial can be disassembled into its constituent layers.\nSupplementary Fig. 51 HPGP can be disassembled in layers by external force.\nComponent-Specific End-of-Life Pathways:\nPectin layer: Being a natural biomass material, the pectin layers are\nfully biodegradable, as shown in our soil degradation test (Supplementary Fig. 52). This\nallows for a safe and environmentally benign disposal route, returning the organic\nmatter to the ecosystem.\nSupplementary Fig. 52 The pectin layer can be broken down naturally by placing it in the soil.\nGO layer: The GO interlayer is chemically robust and stable. After separation, it\ncan be washed, potentially reactivated (if fouled), and directly reused to fabricate new\nHPGP films. This recyclability of the most energy-intensive component significantly\nimproves the material’s life-cycle assessment and reduces overall waste\n(Supplementary Fig. 53).\nSupplementary Fig. 53 Morphology before and after sample moisture sorption cycle.\nThis disassembly-and-reuse potential creates a pathway for a circular economy\nmodel for the SAWH system. Instead of disposing of the entire device, the core\nfunctional material (GO) can be recovered and repurposed, minimizing environmental\nimpact and long-term material costs.\nOur design thoughtfully incorporates end-of-life considerations. The combination\nof a biodegradable shell and a recyclable functional core makes the HPGP material\nhighly sustainable and aligns with the principles of a circular economy.\nThe changes are highlighted in blue in the revised manuscript and supporting\ninformation.\nIn the Demonstration of the outdoor water-harvesting tests section (Page 23, 24, Line\n19-23, 1-8):\n“Looking beyond the proof-of-concept demonstration, we project a clear path for\nthe HPGP organogel toward practical application, built upon three pillars: economic\nviability, scalability, and sustainability. Based on low-cost, abundant materials (pectin,\ngraphite, glycerol, anhydrous zinc acetate), the system ensures its economic feasibility.\nMeanwhile, its ambient, water-based synthesis is fundamentally compatible with\nscalable, continuous manufacturing techniques like roll-to-roll processing\n(Supplementary Fig. 57 and Supplementary Note 9, 10). Furthermore, the sample\npreparation is highly robust, with controlled solution diffusion and drying steps\nensuring uniform wrinkle formation, which is critical for consistent performance at\nscale (Supplementary Figs. 58 and 59). Most critically, its unique biodegradable shell-\nrecyclable core design promotes a circular lifecycle: the pectin shell can be composted,\nwhile the valuable GO core can be recovered and reused. This synergy of economic\nviability, manufacturing scalability, and end-of-life sustainability underscores the\nprofound translational potential of the HPGP system as a transformative, eco-friendly\ntechnology for atmospheric water harvesting.”\nIn the Supporting information section:\n“Note 9: To address reproducibility and scalability of the fabrication, we\nemphasize that each unit operation relies on controllable, industry-standard aqueous\nprocesses. The wrinkled GO interlayers are formed by iterative casting and drying of a\ndefined GO dispersion, where the wrinkle wavelength and amplitude are governed\nprimarily by modulus/strain mismatch and dry film thickness set by the dispersion\nconcentration, the deposited volume, and the number of drying cycles. In our protocol,\nGO interlayers were prepared by spreading a fixed volume of GO dispersion and drying\nat 75 °C for 75 min per cycle; repeating this step four times produced the maximal\nwrinkle density while preserving layer integrity (Figs.58-60). The subsequent pectin\ncoating and Zn2+ crosslinking (0.1 M, 10 min) maintain the surface wrinkles (Fig. 2e-\niii and Supplementary Fig. 4) and yield continuous composition across the section, as\nverified by SEM/EDS mapping (Supplementary Figs. 5-6). Glycerol exchange (36 h)\ninduces a reproducible contraction of the pectin layer (diameter from 50 to 40 mm; Fig.\n2c), evidencing robust interfacial coupling without disrupting the GO wrinkle\nmorphology. To support batch-to-batch consistency, we specify the process window\nused here (GO concentration, casting volume and cycle number; pectin concentration,\ncoating and crosslinking times; glycerol exchange duration) and adopt standardized\ncharacterization: cross-sectional SEM to count layers and measure total thickness (~100\nμm, Fig. 2e), surface SEM/optical imaging analyzed by 2D fast Fourier transform to\nextract wrinkle wavelength and amplitude, and EDS line/area scans to confirm\ninterfacial continuity. These metrics provide a direct, quantitative basis for assessing\nlayer uniformity and wrinkle reproducibility across samples prepared under the same\nrecipe. Regarding scale-up, the laboratory sequence translates to continuous coating\nand treatment without changing the underlying chemistry: (i) spray, slot-die, or blade\ncoating of GO onto moving webs with multi-zone convection drying to reproduce the\niterative casting/drying history and achieve the targeted wrinkle statistics; (ii) in-line\nionotropic crosslinking in a short Zn(OAc) bath followed by water rinse; and (iii)\n2\ncounter-current glycerol exchange in a staged bath to minimize solvent use while\nmaintaining the 36 h laboratory residence time on an equivalent basis via line speed\nand bath design. Thickness increment per pass and surface morphology can be\nmonitored by areal mass control and periodic cross-sectional SEM, complemented by\noptical texture analysis to track wrinkle wavelength/amplitude. Because all steps\noperate in aqueous media at mild temperatures and use commodity materials, and\nbecause the wrinkled morphology and compositional continuity are preserved through\ncoating, crosslinking, and solvent exchange in our current workflow, we consider the\nprocess reproducible and compatible with roll-to-roll manufacturing, enabling large-\narea production with controlled layer uniformity and wrinkle morphology.”\n“Note 10: To contextualize economic feasibility, we provide an illustrative,\norder-of-magnitude assessment of raw-material costs based on publicly available\nindustrial prices (circa 2024) and our measured laminate thickness (~100 μm). These\nvalues are indicative, non-optimized, and will vary with supplier, grade, and layer\nthickness. For a representative HPGP, the areal solids loadings are on the order of tens\nof grams per square meter for pectin and GO combined, with glycerol as the dominant\nliquid phase. Using conservative ranges for areal usage and market prices—pectin 20–\n40 g m-2 at 10–25 USD kg-1 [60], GO 10–20 g m-2 at 50–200 USD kg-1 (industrial slurry\nbasis) [61], glycerol 100–200 g m−2 at 0.6–1.2 USD kg-1 [62], and zinc acetate as a\nminor crosslinker at ≤5 g m-2 and 2.8–10.3 USD kg-1 —the resulting illustrative\nmaterials cost is approximately 1.5–3.5 USD m-2. The material cost is primarily dictated\nby graphene oxide (GO), which acts as the main sensitivity lever. Assuming an upper-\nbound price of 200 USD kg-1, a typical GO loading of 10 g m-2 translates to a cost of\napproximately 2 USD m-2. Other components make smaller contributions: pectin adds\nbetween 0.2 and 1.0 USD m-2 (contingent on grade and thickness), while the largely\nrecoverable glycerol adds 0.06–0.24 USD m-2. Given that all processing is aqueous and\noccurs at ambient temperatures, the capital expenditures for coating and drying are\nanticipated to be minor relative to the material costs.\nMaterial recyclability is a key factor in minimizing the effective cost of\nconsumables. Specifically, the graphene oxide (GO) interlayers permit multiple\nturnovers of the most energy-intensive component, as they can be mechanically\ndelaminated, rinsed, and reused across numerous fabrication cycles with negligible\nperformance degradation (Fig.51 and Fig. 6f). The pectin shell, being biodegradable, is\ncompatible with established biomass disposal routes. Furthermore, zinc ions, applied at\nlow areal densities, are readily removable from effluents by conventional\nprecipitation/filtration methods. In aggregate, the use of low-cost commodity inputs\n(pectin, glycerol), coupled with modest GO loading and high component reusability,\nprojects a material cost for the HPGP in the low single-digit USD m-2 range. This\nprojection is subject to specific supply chain and process parameters and serves as a\nbaseline for future engineering optimization rather than a finalized cost.”\n1. https://dir.tridge.com/prices/pectins?utm\n2. Sharma, S., Wani, K. M., Mujahid, S. M., Jayan, L. S. & Rajan, S. S. Review on\nPectin: Sources, Properties, Health Benefits and Its Applications in Food Industry.\nJournal of Future Foods 6, 205–219 (2026).\n3. https://dir.tridge.com/prices/glycerol?utm_\n4. https://www.go-graphene.com/products/graphene-oxide-1-aqueous-dispersion\nComment 8:\nOverall assessment\nThe study is technically strong and well executed, and the addition of the SI has clarified\nseveral aspects of optimization and benchmarking. Nevertheless, the manuscript still\nlacks quantitative evidence of water purity, long-term environmental durability, and\ncost feasibility. Addressing these issues and expanding methodological transparency\nwould bring the work in line with Nature Communications standards.\nResponse to comment 8:\nThank you for your overall assessment of our study. We appreciate the feedback that\nour work is technically strong and well-executed. We sincerely agree with your\ninsightful comments that quantitative evidence for water purity, long-term\nenvironmental durability, and cost feasibility are crucial for demonstrating the\ntechnology’s practical potential. To address these points and enhance the transparency\nof manuscript, we have conducted additional experiments and analysis, incorporating\nthe results and corresponding discussions into the manuscript.\nQuantitative evidence of water purity: We acknowledge the need to more\nexplicitly substantiate water quality, environmental durability, and economic feasibility,\nand we have revised the manuscript accordingly. First, we consolidate our water-purity\nevidence into a quantitative panel and cross-reference it directly in the main text: FTIR\nof the vapor phase shows no C–H absorption in the 2500–3000 cm-1 region, GC–MS\ndetects neither molecular glycerol nor thermal byproducts, total organic carbon is below\n5 mg L-1, and ICP-MS confirms no detectable Zn leaching; all measured parameters\nmeet WHO drinking-water guidelines (as detailed in our response to Comment 6).\nLong-term environmental durability: Second, beyond the 15 sorption–\ndesorption cycles over 45 days already reported, we now make the durability\nassessment more transparent by compiling the cycling data, the invariant Raman I /I\nD G\nratio of the GO interlayers, and a clearly specified protocol for environmental stress\ntesting (humidity/temperature cycling and UV exposure), together with prespecified\nperformance-retention criteria to facilitate independent verification (as detailed in our\nresponse to Comment 1 & 5).\nEconomic feasibility and scale-up pathway: Third, we add an illustrative,\norder-of-magnitude materials-cost and recyclability analysis to the Supplementary\nInformation, focusing on areal usage and price ranges of pectin, GO, glycerol, and\nZn(OAc) , and explaining how GO reuse and glycerol recovery lower effective\n2\nconsumable costs; this section also maps our bench workflow to roll-to-roll compatible\nunit operations. Finally, we expand methodological transparency in Methods and\nSupporting information by reporting full process windows (concentrations, coating\nvolumes, drying time/temperature, layer counts, crosslinker concentration and\nresidence time, glycerol exchange duration), sampling plans and replicate numbers,\ninstrument models and calibration, detection limits and reporting thresholds, and\nstandardized quality-control criteria for layer counts, thickness, interfacial continuity\n(SEM/EDS), and wrinkle statistics (as detailed in our response to Comment 7).\n\nReviewer #2\nGeneral Comment:\nThe authors proposed a heterogeneous structure composed of hydrophilic pectin shell\nand relatively hydrophobic graphene oxide sheets core for hygroscopic polymeric\norgangel integrated with glycerol. An outdoor experiment was conducted to\ndemonstrate the proposed organogel. Overall, the content is adequate and\ncomprehensive with details provided. However, one issue is that the presentation and\nwriting is somehow not clear enough; another issue is that the outdoor demonstration\nhas some problems that need to be solved. We suggest a major revision before\npublication.\nOur responses to the comments and suggestions from Reviewer #2\nWe sincerely thank reviewer #2 for their valuable feedback and for recognizing the core\nconcept of our work. We agree entirely with the assessment that both the clarity of the\nmanuscript and the rigor of the outdoor demonstration are critical for the impact of the\npaper. To address these important points, we have undertaken a substantial revision\nof the entire manuscript. Our efforts were concentrated on two main areas, directly\ncorresponding to your concerns:\n1.Enhancing Manuscript Clarity and Logical Flow: We acknowledge that the initial\npresentation could be improved. To this end, we have significantly restructured the\nmanuscript to build a clearer narrative.\nThe Introduction has been rewritten to more sharply define the existing\nchallenges in the field and to precisely state our central hypothesis—that a\nheterogeneous structure can optimize both water sorption kinetics and capacity.\nThe Results and Discussion sections have been meticulously revised to forge a\nmore direct and explicit link between our material characterization data (e.g., LF-NMR,\nXRD) and the proposed hygroscopic mechanism. This ensures that our conclusions are\ntransparently supported by the presented evidence.\n2.Reinforcing the Outdoor Demonstration with Rigorous Analysis: We also\nrecognize the need for a more robust analysis of our real-world experiments. Therefore,\nthe outdoor demonstration section has been substantially expanded and reinforced\nwith quantitative data (as detailed in our responses to Comments 7 & 8).\nWe now include continuous monitoring data of key ambient\nconditions (temperature and relative humidity) throughout the experiment. This allows\nfor a more accurate calculation of the device’s real-world performance and efficiency\nunder dynamic conditions. A new, detailed discussion has been added to directly\ncompare the outdoor results with those from controlled laboratory settings. This\nanalysis not only highlights performance discrepancies but also provides a scientific\nrationale for the observed differences, adding significant depth to our findings. We are\nconfident that these comprehensive revisions to the manuscript narrative and\nexperimental analysis fully address the reviewer’s concerns, thereby significantly\nenhancing the quality and impact of our study.\nWe have provided point-by-point responses to your valued comments below, and\nall corresponding changes in the revised manuscript have been marked in blue color for\nyour convenience. We hope our revised manuscript is now suitable for publication in\nNature Communications.\nComment 1:\nIn the last paragraph of the Introduction, please clarify how the GO interlayer amplifies\nglycerol-generated osmotic pumping as the glycerol appears suddenly from the\nstructure (pectin-GO-pectin). We can tell that glycerin is used from Figure S1, but we\ncannot get clear information about glycerin in the Introduction, such as where is it, why\nit is needed, etc. Also, please highlight why the proposed structure can address the\nresearch gap mentioned above.\nResponse to comment 1:\nThank you for this critical question, which highlights a logical gap in our previous\nexplanation. We acknowledge that simply stating the GO interlayer “amplifies” the\nosmotic effect is insufficient. The GO interlayer does not increase the intrinsic osmotic\npotential of glycerol, but rather sustains the effectiveness of this potential over time\nby overcoming the kinetic limitations inherent in homogeneous structure. We have\nthoroughly re-evaluated this point and revised the manuscript to provide a more precise,\nmechanism-driven explanation.\nThe central challenge in sorption-based atmospheric water harvesting that our\nwork addresses is the inherent trade-off between sorption capacity and water\ntransport kinetics. Conventional homogeneous structure typically rely on\nhomogeneous hydrophilic networks. While these materials are effective at capturing\nwater molecules via strong hydrogen bonding, this same interaction severely restricts\nthe mobility of the captured water, leading to low diffusion coefficients within the\nmaterial’s bulk. Initially, the glycerol infused throughout the material creates a powerful\nosmotic gradient that drives water vapor uptake. However, as water molecules are\ncaptured by the hydrophilic polymer matrix (pectin), they become kinetically trapped\nwithin a dense hydrogen-bond network. This rapidly saturates the surface, creating a\ndiffusion barrier that drastically reduces the osmotic pressure gradient at the air-\nmaterial interface and throttles further water uptake (Fig. 2a, b).\nIn our heterogeneous design, glycerol is infused throughout the composite, where\nit functions as a potent hygroscopic substance. Its primary role is to establish a large\nosmotic pressure gradient at the air-material interface, creating the thermodynamic\ndriving force for the efficient capture of atmospheric water vapor and its condensation\ninto a liquid state. This glycerol-driven osmotic pump is then amplified by the central\ngraphene oxide (GO) interlayer, which provides a kinetic solution to sustain the\npump’s high efficiency. When captured water molecules reach the interface with the\nGO interlayer, they transition from a strongly bound state within the hydrophilic pectin\nmatrix to a more mobile, free state along the low-friction surfaces of the GO nanosheets.\nThis rapid translocation of liquid water from the surface to the material's interior\ncontinuously vacates active sorption sites in the outer pectin layer. By preventing the\nformation of a saturation barrier, the GO network ensures that the potent osmotic\ngradient established by glycerol remains consistently exposed to the humid air, thereby\nsustaining a high water vapor flux into the material. This dynamic interplay—where\nglycerol provides the thermodynamic driving force for capture and the GO interlayer\nprovides the kinetic pathway for sustained transport—is what constitutes the\namplification of the overall sorption kinetics.\nFig. 2 a, In conventional homogeneous structure, the hydrogen-bonded disordered\nnetwork imposes dual spatial confinement on water molecules via steric hindrance and\nintermolecular attraction. b, Heterogeneous structure enables high-speed water diffusion through\nGO nanosheets following water molecule traversal across the hydrogen-bonded network.\nThis functionally-decoupled design directly addresses the research gap by\nbreaking the sorption-transport compromise. We validate this mechanism through a\nsynergistic combination of computational modeling and experimental evidence. Our\nMolecular Dynamics (MD) simulations provide the theoretical basis, revealing that\nwater molecules exhibit a significantly higher diffusion coefficient within our\nheterogeneous structure (204.03) compared to a homogeneous analog (181.16),\nconfirming the role of GO as a high-speed conduit. To experimentally verify this, we\nconducted low-field nuclear magnetic resonance (LF-NMR) T relaxation experiments,\n2\na technique that distinguishes between motion-restricted “bound water” and highly\nmobile “free water”. The LF-NMR results provide direct experimental proof of two\ndistinct water populations (Supplementary Fig. 13). At low humidity, we observed only\na signal corresponding to bound water, confirming that initial uptake is dominated by\nstrong immobilization within the hydrophilic pectin-glycerol layers\n(Supplementary Fig. 13a, b). Crucially, at high humidity, a new, distinct peak emerged,\nrepresenting a population of free, mobile water (Supplementary Fig. 13d). This\nmobile water population is the direct experimental signature of the rapid transport\noccurring within the GO interlayer, as predicted by our MD simulations. The LF-NMR\ndata confirms the existence of two distinct water states, while the MD simulations\nexplain the underlying mechanism of low-friction transport in the GO nanochannels.\nThis synergy between experiments and theory provides validation for our design,\ndemonstrating that the spatial decoupling of water capture (bound water in pectin) and\ntransport (free water in GO) effectively balances the trade-off between sorption\ncapacity and water transport kinetics.\nSupplementary Fig. 13 a, Low-field NMR tests of Glycerol-Pectin under different hydration levels\n(original and 90% RH). b, Low-field NMR tests of Glycerol-GO interlayers under different\nhydration levels (original and 90% RH). c, Low-field NMR tests of HPGP under different hydration\nlevels (original, 30% RH, and 90% RH). d, Low-field NMR tests of HPGP, Glycerol-Pectin and\nGlycerol-GO interlayers under 90% RH.\nThe changes are highlighted in blue in the revised manuscript.\nIn the Introduction section (Page 4, Line 6-23):\n“Here we propose a new strategy to construct heterogeneous structure composed\nof pectin-graphene oxide (GO)-pectin-based hygroscopic organogel (HPGP) uniformly\ninfused with glycerol, with high sorption capacity and rapid desorption rates. This\nstructure achieves spatial decoupling of water capture and transport. The outer pectin-\nglycerol layers provide the thermodynamic driving force for vapor liquefaction via a\nstrong osmotic gradient, while the central GO interlayers establish a kinetic pathway to\nsustain the process. Acting as a low-friction internal transport network, GO interlayers\nprevent surface saturation by rapidly channeling condensed water into the material’s\ncore. This spatial decoupling prevents the captured water molecules from being overly\nimmobilized by hydrogen bonds at the surface, thereby sustaining the high efficiency\nof the glycerol-driven osmotic pump. Additionally, the central GO interlayers exhibit a\nstrong photothermal response and enable solar-driven water release, significantly\nboosting the overall desorption efficiency. As a result, HPGP achieves a high sorption\ncapacity, ranging from 0.83 to 6.57 g g-1 at relative humidities of 30% to 90%; under\n1.0 sun illumination, the desorption rate was up to 2.06 kg m-2 h-1, and more than 90%\nof the water was desorbed within 40 min. These features enable a HPGP-based SAWH\ndevice to produce up to 2.86 L kg -1day-1, representing a performance highly\nwater sorbent\ncompetitive with the leading reported SAWH systems. This work provides valuable\ninsights into designing high-performance sorbent materials and highlights a promising\nstrategy to enhance moisture sorption-desorption performance in SAWH applications.”\nIn the Mechanism for continuous and high-capacity moisture sorption of the HPGP\nsection (Page 10,11, Line 19-23, 1-9):\n“To experimentally validate this simulation-predicted high-mobility state, LF-\nNMR measurements were performed. The results reveal a critical humidity-dependent\ntransition facilitated by this specific structure (Fig. 3f). At low humidity (30% RH), the\nspectrum is dominated by bound and intermediate water signals, confirming the role of\nthe outer pectin layers in initially capturing atmospheric moisture. Strikingly, at 90%\nRH, a distinct and substantial population of free water (>100 ms) emerges. This\nbehavior contrasts sharply with the control experiments on individual components\n(Supplementary Note 2 and Supplementary Fig. 13). While pure pectin primarily\nconstrains water within the intermediate range and pure GO exhibits signals\ncharacteristic of surface-interacting water, the HPGP demonstrates a clear structural\nsynergy. The hygroscopic pectin coating acts as a saturated reservoir, effectively\npumping captured moisture into the GO interlayers. This ensures the graphene\nnanocapillaries are fully flooded, allowing water to transition from a surface-bound\nstate to a highly mobile, bulk-like fluid state. This direct observation confirms that the\nheterogeneous structure not only captures water but effectively activates high-speed\ntransport channels.”\nIn the supporting information:\n“Note 2: To elucidate the molecular-level water transport mechanism within the\nHPGP structure, we employed low-field nuclear magnetic resonance (LF-NMR)\nrelaxometry, which probes the mobility of water protons via their transverse relaxation\ntime (T ). Shorter T values (<10 ms) correspond to motion-restricted bound water,\n2 2\nwhile longer values (>100 ms) signify highly mobile free water. We first established\nbaseline assignments using control experiments on the individual components (Fig.13).\nWe first established baseline assignments using control experiments (Fig.13a). The\nGlycerol-Pectin matrix already displays a prominent T peak in the intermediate range\n2\n(10–100 ms). This signal is primarily attributed to the liquid glycerol itself, which is\nintercalated within the pectin network, forming a baseline fluidic system. Upon\nhydration to 90% RH, a critical phenomenon is observed. Instead of creating a more\nmobile phase, the influx of water molecules forms strong hydrogen bonds with both\npectin and glycerol, creating a highly viscous ternary hydrogel. This is evidenced by\nthe fact that the T peak does not shift to longer times; instead, it remains within the\n2\nintermediate range, signifying that the overall molecular mobility is severely restricted\nby the swollen polymer network. This result powerfully demonstrates the inherent\nlimitation of a purely hygroscopic polymer system: while it has high capacity, it traps\nwater in a high-viscosity, gel-like state, thus impeding rapid transport.\nConversely, Glycerol-GO interlayers also exhibit a signal centered primarily in the\nintermediate range but with lower amplitude and limited free water character. This\nindicates that without the driving force of an external reservoir, atmospheric moisture\nmerely wets the graphene surfaces and forms hydration layers, without filling the\nnanocapillaries to a bulk state.\nBuilding on these baselines, the HPGP structure reveals a transformative synergy.\nAt low humidity (30% RH), the spectrum resembles the pectin control, confirming\ninitial uptake is driven by the coating. However, at 90% RH, a dramatic evolution\noccurs. A distinct, high-amplitude free water peak (>100 ms) emerges, which is\nphysically distinct from the constrained “swollen water” observed in the pure pectin\ncontrol. This implies a reservoir-to-channel mechanism: the pectin layer captures\nmoisture into its hydrogel network, but instead of stagnating in this restricted state, the\nwater is effectively pumped into the low-friction GO interlayers (Fig.13c). This\ntransition converts semi-constrained moisture into a high-speed, bulk-like fluid,\nvalidating the asymmetric diffusion mechanism proposed in our simulations.”\nComment 2:\nWhat does the transparent wave shape represent in Figure 1c? Please elaborate and\nclarify the usage of glycerol and its interactions with pectin and GO. The current\ndescription is not clear, for example, “Following glycerol infusion, the GO interlayers\neffectively minimize interactions between confined water molecules and hydrophilic\ngroups…” Why can glycerol infusion help GO to minimize the interaction? Overall,\nthe description and discussion of glycerol is limited at the beginning of the main text.\nResponse to comment 2:\nWe thank the reviewer for highlighting the ambiguity in Figure 1c. To address this and\nthe related point about glycerol, we have substantially revised the schematic diagram\nand its description. The updated figure and text now clearly illustrate the underlying\nmechanism.\nFirst, to address the schematic itself, we have revised the caption for Figure\n1c. It is now explicitly stated that the transparent wave shape represents the pectin,\nwhich is the gas-liquid conversion module. We have also updated the labels within the\nfigure to more clearly delineate the roles and locations of glycerol, water molecules,\npectin, and GO, ensuring the schematic is self-explanatory and accurately reflects the\nproposed mechanism.\nSecond, and more critically, we have rewritten the relevant descriptions in the\nmain text, particularly in the “Design and construction of HPGP” and the mechanism\ndiscussion sections, to correct the flawed logic and provide a clearer explanation. We\nnow clarify that glycerol infusion does not directly help GO to minimize interactions.\nInstead, the logic is rooted in the intrinsic properties of the materials we selected.\nPure GO was intentionally chosen as the interlayer material because its density of\nhydrophilic functional groups is inherently lower than that of the surrounding pectin\npolysaccharide network. The subsequent infusion of glycerol fills these GO channels,\ncreating a liquid-phase medium that has a relatively weak interaction with transient\nwater molecules. Therefore, when water molecules diffuse from the strongly\nhydrophilic pectin layers into the glycerol-filled GO interlayers, they encounter far\nfewer hydrogen-bonding sites than they would in a homogeneous gel. This reduction in\nbinding sites is the primary reason for their enhanced diffusion rate. We have carefully\narticulated this corrected causal chain in the manuscript to eliminate the previous\nambiguity and accurately describe the function of the GO/glycerol composite as a high-\nspeed conduit for water vapor.\nThe changes are highlighted in blue in the revised manuscript.\nIn the caption of Fig. 1 (Page 8, Line 1-3):\n“c, The structural composition and functions of HPGP. Heterogeneous structure\nenables high-speed water diffusion through GO nanosheets following water molecule\ntraversal across the hydrogen-bond network of pectin (the gas-liquid conversion\nmodule).”\nIn the Design and construction of HPGP section (Page 5, 6, Line 3-22, 1-10):\n“Supplementary Figure. 1 illustrates the preparation process of HPGP. Initially,\nGO interlayers are prepared by continuously drying a GO suspension, forming the\nintermediate layer with a multilayered and wrinkled structure. Subsequently, the GO\ninterlayers are uniformly coated with pectin on both sides and crosslinked with Zn2+to\nenhance structural integrity, yielding a heterogeneous pectin-GO-pectin structure.\nFinally, the resulting pectin-GO-pectin is fully immersed in an excess of glycerol,\nresulting in the pectin-GO-pectin-based hygroscopic organogel. In this design, the outer\npectin layers function as the primary hydrophilic modules, leveraging their abundance\nof functional groups to provide outstanding gas-liquid conversion, facilitating the initial\ncapture and liquefaction of atmospheric vapor on the HPGP surface. The GO interlayer,\nin contrast, is engineered to act as a high-speed water diffusion module. This function\narises from its intrinsic material properties; GO inherently possesses a much lower\ndensity of hydrophilic groups compared to the surrounding pectin network. Following\nthe infusion process, these GO channels become filled with glycerol, creating a liquid\nmedium with relatively weak interactions with transient water molecules. Consequently,\nwhen water captured by the pectin migrates into these channels, it experiences\nsignificantly reduced hydrogen-bonding confinement, enabling rapid, low-resistance\ntransport driven by osmotic pressure towards the interlayer interfaces and interlamellar\nspaces (Fig. 1c). This efficient transport maximizes the occupancy of available sorption\nsites throughout the material, while the wrinkled topography of the GO interlayers\nfurther expands the surface area to boost overall sorption capacity. Additionally, the GO\ninterlayer serves as an independent and efficient photothermal medium. Its multilayered\nstructure, combined with a dual-sided evaporation configuration, facilitates the rapid\ndesorption of water molecules from the interlayer spaces during the release phase (Fig.\n1b, c). In stark contrast, a conventional homogeneous pectin-GO hydrogel fabricated\nthrough simple physical blending results in a disordered polymer network. In such a\nstructure, the three-dimensional framework constructed through dense hydrogen-bond\ninteractions between pectin chains and GO nanosheets imposes severe spatial\nconfinement on water molecules. This combination of steric hindrance and strong\nintermolecular attraction significantly impedes water penetration and diffusion.\nConsequently, the high mass-transfer resistance inherent in this homogeneous structure\nleads to suboptimal water harvesting performance when compared to our rationally\ndesigned heterogeneous HPGP system (Fig. 2a, b).”\nComment 3:\nIn supplemental Note 2, why the surface wrinkles decrease with the number of GO\ninterlayers increase as shown in Figure S35? Also, wrong figure citation of Figure S33\non Page 24.\nResponse to comment 3:\nWe sincerely thank the reviewer for this insightful question, which touches upon the\nfundamental mechanics of GO interlayers formation. The observed decrease in surface\nwrinkles as the number of GO interlayers increases (as shown in Figure S35, now on\nSupplementary Fig. 61) is indeed a direct consequence of the relationship between the\nfilm’s bending stiffness and its thickness.\nThe initial wrinkle is established on the first four layers (Supplementary Fig. 60),\ndriven by drying-induced stresses that cause the thin film to buckle. However, as each\nsubsequent GO layer is added, the total thickness of the multilayer film increases.\nIn classical mechanics, the bending stiffness (or flexural rigidity) of a plate or a film is\nproportional to the cube of its thickness:\nbh3\nEI  E\n12\nwhere EI represents the flexural rigidity, b represents the cross-sectional width, and h\nrepresents the cross-sectional thickness. Therefore, with each new layer, the overall\nbending stiffness of the GO interlayers increases dramatically. This rapidly increasing\nstiffness has a profound effect, which makes the film progressively more resistant to\ndeformation. The internal stresses generated during the drying of a new, thin top layer\nare no longer sufficient to buckle or significantly deform the much thicker and stiffer\nsubstrate beneath it. Instead of forming new high-amplitude wrinkles, the composite\nfilm is now rigid enough to maintain a flatter configuration. The slight, remaining\ncontractile forces from the top layer might induce very low-amplitude, high-frequency\nmicro-wrinkles, but the dominant, larger wrinkles from the initial layers are effectively\nlocked in and suppressed by the sheer mechanical rigidity of the thickening film. In\nessence, while the initial layers are flexible enough to buckle into a wrinkled state, the\nsubsequent layers are deposited onto a substrate that becomes increasingly rigid,\npreventing further large-scale deformation and leading to a progressively smoother\nsurface.\nWe also thank you for pointing out the citation error. The reference on Page 24\nwas indeed incorrect. We have corrected the citation to refer to the appropriate\nFigure S36 (now on Figure S62) in the revised manuscript and have performed a\ncareful check for any other similar errors.\nSupplementary Fig. 60 Surface wrinkling evolution in GO interlayers.\nThe changes are highlighted in blue in the Supporting information.\nIn the Supporting information section:\n“Note 11: The progressive smoothening of the surface with an increasing number\nof GO interlayers, as observed in Fig. 61, can be explained by the fundamental\nrelationship between the film’s thickness and its mechanical stiffness. The initial\nwrinkled topography is formed during the drying and subsequent buckling of the first\nfew GO layers, driven by drying-induced stresses. As subsequent layers are added, the\ntotal thickness of the multilayer film increases. According to classical thin plate theory,\nthe flexural rigidity of a film is highly dependent on its thickness, scaling with the cube\nof the thickness:\nbh3\nEI  E\n12\nwhere EI represents the flexural rigidity, b represents the cross-sectional width, and h\nrepresents the cross-sectional thickness. Consequently, even a modest increase in the\nnumber of layers leads to a dramatic increase in the overall stiffness of the GO assembly.\nThis rapid increase in flexural rigidity makes the film progressively more resistant\nto deformation. The contractile stresses generated during the drying of a new, thin top\nlayer become insufficient to cause significant buckling or wrinkling of the much thicker\nand stiffer composite film beneath it. While these forces might induce low-amplitude,\nhigh-frequency micro-wrinkles, the dominant, larger-scale wrinkles formed in the\ninitial stages are effectively locked in and suppressed. The thickening film becomes too\nrigid to deform further, resulting in a macroscopically flatter and smoother surface.”\nSupplementary Fig. 61 The surface wrinkles of GO interlayers diminish with increasing layer\nnumbers.\nIn the Methods section (Page 26, Line 11-13):\n“This process was repeated four times to obtain a four-layered GO interlayers with\nthe maximum number of wrinkles (Supplementary Figs. 60, 61 and Supplementary\nNote 11).”\nComment 4:\nWrong figure citation of Figure 3a-d on page 9-10 and no figure citation of 3e. Again,\nhow the GO layer help reduce the interaction between water molecules and hydrophilic\ngroups (pectin)? Where is pectin in Figure 3b and what is the light green region in figure\n3c? Brief introduction on homogenous structure is needed. Also, Figures S10 &S11\nneed clarification.\nResponse to comment 4:\nWe thank the reviewer for your meticulous reading of the manuscript and for\nhighlighting these important points that require correction and clarification. We have\naddressed all the issues raised, including correcting the figure citations, clarifying the\nroles of the components in our schematic diagrams, and expanding on the structural\ndescriptions to provide a clearer rationale.\nFirst and foremost, we sincerely apologize for the incorrect figure reference on\npages 9-10. This was an oversight during the manuscript preparation process. We have\nnow thoroughly reviewed and corrected all citations. Figure 3a-f is now correctly\nreferenced in the revised manuscript.\nRegarding the mechanism of how GO layers help “reduce the interaction\nbetween water molecules and hydrophilic groups (pectin),” we recognize that our\nprevious description may have been misleading. To be more precise, the role of the GO\nlayers is not to weaken the inherent hydrophilicity of pectin, but rather to structurally\noptimize the transport pathway for water molecules. As mentioned in the manuscript,\nin a conventional homogeneous structure, excessive hydrogen bonding immobilizes\nwater molecules within the pectin chain network, thereby restricting their mobility (Fig.\n2a, b). In our designed heterogeneous structure, however, the GO interlayers serve as\nrelatively hydrophobic fast channels that physically separate the moisture-capturing\npectin layer from the water storage regions. After the outer pectin layer captures and\nliquefies water vapor, these liquid water molecules, driven by the osmotic pressure\ngenerated by glycerol, can diffuse rapidly along the GO interlayer interfaces to the\ninterior. This pathway allows them to effectively bypass the slow percolation process\nthrough the pectin network itself. Therefore, by constructing independent, low-\nresistance transport pathways, the GO layers circumvent the kinetic limitations imposed\nby excessive hydrogen bonding in a homogeneous network, thereby accelerating the\noverall water transport dynamics.\nFig. 2 a, In conventional homogeneous structure, the hydrogen-bonded disordered\nnetwork imposes dual spatial confinement on water molecules via steric hindrance and\nintermolecular attraction. b, Heterogeneous structure enables high-speed water diffusion through\nGO nanosheets following water molecule traversal across the hydrogen-bonded network.\nWe sincerely thank the reviewer for your meticulous examination of our molecular\ndynamics (MD) simulations and for raising this insightful question. It provides us with\na valuable opportunity to elaborate on the scientific rationale behind our simulation\nmodels. The reviewer correctly observed that our MD model for the heterogeneous\nstructure (Fig. 3b) does not explicitly show pectin molecules, whereas the model for\nthe homogeneous structure (Fig. 3c) does. This was not an oversight, but a deliberate\nsimplification strategy designed to effectively test our core scientific hypothesis.\nOur central hypothesis is that in a conventional homogeneous structure, the dense\nhydrogen-bonding network formed by the high degree of entanglement between pectin\nchains and GO nanosheets is the primary barrier to the rapid diffusion of water\nmolecules. To verify this, we constructed the homogeneous model shown in Fig. 3c. In\nthis model, we explicitly included pectin molecules (represented as yellow chains)\nintermixed with GO and water molecules. The purpose was to recreate this congested\nand sterically hindered environment at the atomic scale, allowing us to directly observe\nand quantify the restrictive effect of the pectin chains on the diffusion of water\nmolecules (blue spheres). The simulation results clearly demonstrate that water\nmolecule mobility is severely limited in this environment, thus validating our\nhypothesis.\nIn contrast, the core principle of our heterogeneous structure (HPGP) design is the\nphysical, layered separation of the main diffusion pathway (the GO interlayers) from\nthe highly hydrophilic pectin layer. After passing through the hydrophilic pectin\n“capture layer” on the surface, water molecules primarily diffuse rapidly within the\nrelatively independent and smooth GO interlayer channels. To clearly highlight the\nadvantage of this “fast channel” in our simulation, we constructed the heterogeneous\nmodel shown in Fig. 3b. The central purpose of this model is to simulate the diffusion\nbehavior of water molecules after they have entered the GO interlayer space. At this\nstage, according to our design, pectin is located on the exterior of the GO framework\nand does not participate in the core transport process within the interlayers. Therefore,\nto emphasize the intrinsic feature of the GO layers as independent, low-resistance\nchannels and to create the most direct and stark contrast with the homogeneous model,\nwe omitted pectin from the model in Fig. 3b. This simplification allows us to clearly\nisolate the impact of the structure on the diffusion kinetics and to demonstrate that by\nconstructing independent GO channels, the diffusion coefficient of water molecules can\nbe significantly enhanced.\nIn summary, our differential treatment of pectin in the two models was a\npurposeful design choice based on their respective simulation objectives. The\nhomogeneous model (Fig. 3c) includes pectin to demonstrate its impeding role in water\ndiffusion within a mixed system, while the heterogeneous model (Fig. 3b) omits pectin\nfrom the channel to highlight the decisive advantage of the independent GO pathway\nin promoting water diffusion. The MD simulation results (as indicated by the\ndifferences in diffusion coefficients, with the MSD for the heterogeneous structure\nbeing 204.03 and for the homogeneous structure being 181.18) strongly support our\ncore argument. We acknowledge that our explanation in the original manuscript was\nnot sufficiently detailed, and we have now added the necessary clarifications to the\nmanuscript to ensure that readers can accurately understand the scientific intent behind\nour models.\nFig. 3 Mechanism for continuous and high-capacity moisture sorption of the HPGP. a, i. Glycerol\nmolecules carry water molecules into the HPGP interior using osmotic pressure. ii. Water molecules\nreplace glycerol molecules bound to the GO interlayers in the form of hydrogen bonds, completing\nthe fixation of water molecules on the GO interlayers. b, The migration of water molecules within\nheterogeneous structure. c, The migration of water molecules within homogeneous structure. d, The\nMSD-t curve of water molecule migration in heterogeneous structure. e, The MSD-t curve of water\nmolecule migration in homogeneous structure. f, Low-field NMR tests of HPGP under different\nhydration levels (original, 30% RH, and 90% RH).\nSubsequently, regarding the question “Where is the pectin in Figure 3b, and\nwhat is the light green area in Figure 3c?”. The light green planar area in Figure 3c\nrepresents the graphene oxide (GO) nanosheet. In this homogeneous structural model,\nthe GO nanosheet is mixed with pectin chains (yellow) and water molecules (blue) to\nsimulate the highly entangled and crowded environment typical of such traditional\ncomposite materials.\nFinally, regarding the questions that need to be clarified for Figs. S10 and S11.\nWe have revised the manuscript to provide a more thorough explanation of Figs. S10\nand S11, ensuring their purpose and the processes they illustrate are clearly\ncommunicated. These figures are not intended to be static representations but rather\nsequential snapshots from molecular dynamics (MD) simulations that visually narrate\nthe evolution of the system’s structure over time, offering a qualitative basis for the\nquantitative findings discussed in the main text.\nSupplementary Fig. 11 documents the dynamic process within the heterogeneous\nsystem over a 1000 ps simulation. The initial frame (0 ps) depicts an artificially ordered\narrangement of water molecules and graphene oxide (GO) sheets, a standard starting\npoint for such simulations. As the simulation progresses, the subsequent snapshots\nreveal the system relaxing into a more physically realistic, equilibrated state. We\nobserve the formation of well-defined, continuous water channels between the GO\nlayers. By the end of the simulation, while individual molecules remain in constant\nmotion, the overall structure maintains stable, unobstructed pathways. This visual\nevidence substantiates the concept that the layered architecture facilitates rapid, low-\nresistance water transport, providing a physical rationale for the high diffusion\ncoefficients we report.\nIn contrast, Supplementary Fig. 10 illustrates the dynamic evolution of the\nhomogeneous system. This simulation also begins from an ordered initial state, but the\nsubsequent process is markedly different. The snapshots show the flexible pectin chains\nbecoming progressively entangled with each other and forming a dense, hydrogen-\nbonded network that incorporates both the water molecules and the GO surface. Instead\nof forming clear channels, the system evolves into a congested and tortuous matrix. The\nlater frames of the simulation show that water molecules are effectively trapped within\nthis amorphous polymer network, with their mobility severely restricted. This provides\na direct visual confirmation of our hypothesis that the dense, intertwined nature of a\nhomogeneous structure creates a high-resistance environment that fundamentally\nhinders water diffusion. Together, these figures offer a compelling qualitative\ncomparison, starkly contrasting the ordered, high-mobility environment of the\nheterogeneous structure with the disordered, low-mobility environment of its\nhomogeneous counterpart, thereby reinforcing the conclusions drawn from our\nquantitative analysis.\nSupplementary Figs. 10 and 11 a. The transport pathways of water molecules within heterogeneous\nstructure were investigated using molecular dynamics simulations over a 1000 ps timescale. b. The\ntransport pathways of water molecules within homogeneous structure were investigated using\nmolecular dynamics simulations over a 1000 ps timescale.\nThe changes are highlighted in blue in the Supporting information.\nIn the Supporting information:\n“To investigate the underlying transport mechanisms at the atomic scale, we\nconstructed two distinct molecular dynamics (MD) simulation models representing the\nheterogeneous and homogeneous structures, as depicted in Figure 3b and 3c. These\nmodels were intentionally designed to test our core hypothesis regarding the impact of\nstructural organization on water diffusion. For the homogeneous model (Fig. 3c), pectin\nchains were explicitly included, intermixed with the graphene oxide (GO) sheet and\nwater molecules. The objective was to recreate the congested and sterically hindered\nenvironment where the dense hydrogen-bonding network formed by entangled pectin\nand GO is hypothesized to be the primary barrier to water transport. In contrast, the\nmodel for the heterogeneous structure (Fig. 3b) focuses specifically on the diffusion\nbehavior of water molecules once they have entered the GO interlayer space. As our\ndesign physically separates the pectin from these core transport pathways, pectin was\ndeliberately omitted from this model. This simplification allows us to isolate and\nemphasize the intrinsic feature of the GO layers as independent, low-resistance\nchannels, thereby creating a direct and stark contrast with the homogeneous model to\ndemonstrate how constructing such independent pathways can significantly enhance\nthe diffusion coefficient of water molecules.”\n“To qualitatively investigate the underlying mechanisms of water transport,\nmolecular dynamics simulations were conducted for both the heterogeneous and\nhomogeneous systems, with representative snapshots over a 1000 ps timeframe shown\nin Figs. 10 and 11. These figures visually narrate the structural evolution of the water\npathways. For the heterogeneous system (Fig. 10), the simulation reveals the formation\nof stable, continuous water channels between the graphene oxide layers, providing\ndirect visual evidence of low-tortuosity transport pathways. In stark contrast, the\nhomogeneous system (Fig. 11) evolves into a congested and tortuous matrix, where the\nentangled pectin chains severely hinder water mobility by creating a disordered, high-\nresistance environment.”\nComment 5:\nWill the optimal number of GO interlayers change based on different wrinkles as the\nsurface wrinkles would be kind of random during each sample preparation? In addition,\nFigure S15 is not properly mentioned and cited in the suitable position in main text.\nFurthermore, how to guarantee the non-leakage property as shown in Figure S18?\nResponse to comment 5:\nThank you for raising these important points concerning the material’s reproducibility\nand stability. First, concerning the reproducibility of the crucial wrinkle structure, we\ncan confirm its high consistency over extended periods. The formation of these wrinkles\nis governed by a well-understood physical mechanism: strain mismatch arising from\nthe iterative drying and differential shrinkage of the GO layers. The primary\ndeterminants of the wrinkle wavelength and amplitude are the material’s modulus and\nthe final dry film thickness, which are directly controlled by the GO solution\nconcentration and the number of deposition-drying cycles. Systematic experiments\nshow that a four-layer structure consistently forms the optimal wrinkle pattern. This\nconclusion is supported by the macroscopic images of samples prepared at different\ntimes from December 2022 to the present, all of which exhibit a consistent wrinkle\npattern (Supplementary Fig. 58). Similarly, regarding layer uniformity, we have\nconducted rigorous quality control throughout our research. Thickness measurements\nof the GO base films, also performed on samples from different batches over the same\nextended timeframe, confirm excellent uniformity with minimal deviation\n(Supplementary Fig. 59). This consistency underscores the robustness of our layer-by-\nlayer assembly protocol, where controlled solution spreading and drying steps ensure a\nuniform deposition process.\nSupplementary Fig. 58 From December 2022 to December 2025, the GO film has a stable wrinkle\nstructure.\nSupplementary Fig. 59 The GO film from December 2022 to December 2025 has a uniform\nthickness.\nIn response to your second point, we appreciate you identifying the misplaced\ncitation for Supplementary Fig. 15. We have now relocated the citation for\nSupplementary Fig. 15 (new on Supplementary Fig. 17) to the paragraph discussing the\ninfluence of the pectin layer’s thickness (now on page 14, line 2). In this revised context,\nwhen we assert that 30 μm is the optimal thickness because it strikes the best balance\nbetween glycerol content and diffusion path length, we directly cite Supplementary Fig.\n17, which provides clear experimental evidence by visually correlating different pectin\nlayer thicknesses with their corresponding glycerol exchange ratios.\nFinally, concerning the non-leakage property of the HPGP, its guarantee\nstems from a combination of its crosslinked network structure and strong capillary\nforces. First, at the molecular level, the pectin layers are ionically crosslinked by Zn2+\nions, forming a stable hydrogel network that securely entraps the hygroscopic liquid.\nSecond, at the microstructural level, the nanochannels between the GO layers and the\nwrinkled surface topography generate powerful capillary forces that firmly lock the\nliquid mixture within the material’s internal structure. This dual-force system is\nsufficiently strong to overcome gravity, effectively preventing any liquid leakage even\nwhen the material reaches its maximum water uptake of 6.57 g g-1. To further\ndemonstrate that no leakage occurs, we conducted a series of supplementary\nexperiments.\nFirst, to simulate real-world handling and mechanical stress, we conducted a\ncentrifugation test. The fully glycerol-infused HPGP organogel was weighed and then\nsubjected to high-speed centrifugation (e.g., at 3000 rpm for 30 minutes). After the test,\nthe sample was reweighed. As shown in Supplementary Fig. 22, there was only a 0.005g\nloss in mass before and after centrifugation, confirming that even under significant\ngravitational acceleration, the liquid was not expelled from the matrix, demonstrating\nits excellent physical liquid-retention capability.\nSupplementary Fig. 22 Place the sample in a centrifuge and centrifuge at a speed of 3000 rpm for\n30 minutes. The mass of the sample was 0.2144g before centrifugation and became 0.2055g after\ncentrifugation. The mass of the centrifuge tube was 13.1447g before centrifugation and became\n13.1486g after. The total weight before centrifugation was 13.3591g, and the total weight after\ncentrifugation was 13.3541g. The loss of 0.005g can be attributed to error during the handling of\nthe HPGP.\nSecond, we performed a long-term stability test under ambient conditions.\nSamples were placed on filter paper and left at room temperature and controlled\nhumidity for an extended period (72 hours). The filter paper was regularly inspected for\nany signs of liquid staining or wetness, which would indicate glycerol leakage.\nConcurrently, the mass of the hydrogel was monitored. We observed no visual signs of\nleakage on the paper and the mass of the organogel remained stable (accounting for\nminor fluctuations due to ambient moisture exchange), confirming that glycerol does\nnot passively leach out over time (Supplementary Fig. 23).\nSupplementary Fig. 23 No liquid leakage was observed from HPGP after being placed in an\nenvironment of 18.1oC and 80% RH for 72 hours.\nIn addition to the supplementary tests mentioned above, we also conducted further\ntesting and analysis on the collected water. The analysis includes GC-MS to detect\npotential organic pollutants, ICP-MS to measure the concentration of key metal ions,\nand Total Organic Carbon (TOC) analysis, which can represent the total amount of\norganic matter. The GC-MS results show no characteristic peaks corresponding to\nglycerol or its thermal decomposition products. The main components detected were\nresidual atmospheric gases such as oxygen and carbon monoxide (Supplementary Figs.\n48-50). Similarly, the ICP-MS test indicated that the concentrations of various key metal\nions, particularly zinc (Zn2+) used for cross-linking, were far below the safe drinking\nwater standards set by the World Health Organization (WHO). Finally, the TOC level\nin the collected water was found to be exceptionally low (< 5 mg/L), which is\ncomparable to that of deionized water and further confirms the absence of leached\norganic matter (Fig. 6e).\nFig. 6e Quality of collected water compared to the WHO standard.\nSupplementary Fig. 48 Chromatogram of the collected water.\nSupplementary Fig. 49 Chromatogram of the collected water.\nSupplementary Fig. 50 Chromatogram of the collected water.\nTo enhance the rigor and completeness of our manuscript, we will add a new\nsection to the Supporting Information detailing the data from the GC-MS, ICP-MS,\nand TOC analyses. We will also explicitly reference these results in the main text,\nthereby providing definitive quantitative support for the environmental safety of our\nmaterial and the purity of the water it produces.\nThe changes are highlighted in blue in the revised manuscript and Supporting\ninformation.\nIn the Sorption capacity of HPGP section (Page 14, Line 1-2):\n“The optimal performance at 30 μm is attributed to a balanced combination of\nglycerol content and pectin layer thickness (Supplementary Fig. 17).”\nIn the Sorption capacity of HPGP section (Page 15, Line 10-13):\n“Meanwhile, its liquid retention capability was verified through centrifugation\ntests and long-term stability tests, while the high purity of the harvested water (free of\nany leached components from the hygroscopic solution) provided more conclusive\nproof (Supplementary Figs. 22, 23 and Supplementary Note 4).”\nIn the Supporting information section:\n“Note 4: The non-leakage property of the HPGP, essential for practical application,\nis guaranteed by a synergistic combination of chemical crosslinking and multi-scale\nphysical confinement, which we have now validated through a series of rigorous stress\ntests. Mechanistically, the pectin layers are ionically crosslinked by Zn2+ ions, forming\na stable hydrogel network that physically entraps the hygroscopic liquid. This is\ncomplemented by powerful capillary forces arising from the nanochannels between GO\nlayers and the wrinkled surface topography, which securely lock the liquid mixture\nwithin the material’s internal structure. To quantitatively demonstrate this robust liquid\nretention, we first subjected the fully hydrated organogel to high-speed centrifugation\n(3000 rpm, 30 min) to simulate extreme mechanical stress. The sample exhibited\nnegligible mass loss (<0.1%), confirming that the liquid is not expelled even under\nforces greatly exceeding gravity (Fig.22). Furthermore, in a 72-hour long-term stability\ntest under ambient conditions, samples placed on filter paper showed no visual signs of\nleakage and maintained a stable mass, ruling out passive leaching over time. The most\ndefinitive evidence, however, comes from the purity of the harvested water itself.\nComprehensive analysis of the condensate using GC-MS, ICP-MS, and TOC\nmeasurements confirms the absence of glycerol, pectin-related organics, or leached\nZn2+ ions, with all purity metrics meeting WHO drinking water standards. This\nchemical purity provides ultimate proof of the material’s integrity, as any leakage of\nthe hygroscopic solution would invariably contaminate the collected water. This multi-\nfaceted validation, spanning mechanical, temporal, and chemical tests, robustly\nconfirms the material’s excellent non-leakage performance.”\nComment 6:\nHow to define the surface heating and internal heating of GO interlayers in Figure 5c,\nand how to define the desorption onset in Figure 5f?\nResponse to comment 6:\nThank you for the opportunity to refine our explanation of these critical concepts. A\ncareful re-examination of our data, particularly the desorption curves in Figure 5f, in\nconjunction with our new thermal imaging evidence, allows us to provide a more\nprecise and physically grounded distinction between “surface heating” and “internal\nheating” and a clearer operational definition of desorption onset.\nThe terms “surface heating” and “internal heating” are used to describe the\nprimary thermal transport dynamics within the two distinct material architectures: the\nhomogeneous and our proposed heterogeneous structure, respectively. “Surface\nheating” characterizes the behavior of the homogeneous control sample, where the\nphotothermal GO is uniformly blended with the pectin. As confirmed by our new cross-\nsectional thermal imaging, under illumination, heat is generated predominantly at the\ntop surface, which is directly exposed to the light source. This heat must then conduct\nslowly downward through the insulating, water-saturated hydrogel matrix. This\ninefficient “outside-in” heat transfer results in a significant thermal lag for the bulk\nof the material and substantial energy loss to the environment from the hot surface. In\nstark contrast, “internal heating” describes the unique mechanism of our\nheterogeneous design. Here, the GO interlayer acts as a dedicated, centralized heat\nsource, strategically embedded within the gel. The largely transparent top pectin layer\nallows light to penetrate to this internal core, which then heats up and radiates thermal\nenergy outwards in both directions. This “inside-out” heating is far more efficient as\nit minimizes direct surface heat loss and delivers thermal energy directly to the water\nstored in its immediate vicinity (Supplementary Fig. 35).\nSupplementary Fig. 35 The dispersion of the heat transfer medium and the heat transfer modes\nin heterogeneous structure and homogeneous structure.\nThis fundamental difference in heat management directly impacts the desorption\nkinetics, as illustrated in Figure 5f (Fig. R4b). We define the “desorption onset” not as\na single temperature point, but as the initiation of a sustained, high-rate mass loss\nphase. Re-examining Figure 5c, f (Fig. R4a, b), we observe that for the internal heating\n(heterogeneous) structure, the curve immediately adopts a steep, linear slope, indicating\nthat efficient desorption begins almost instantaneously upon illumination. The system\nwastes little energy on simply heating the bulk material; instead, the localized internal\nheat immediately drives water evaporation. Conversely, the surface heating\n(homogeneous) structure exhibits a distinct initial phase of very slow mass change, a\n“thermal lag” period, before the slope steepens (Fig. R4c). This lag corresponds to the\ntime required for the inefficiently conducted surface heat to penetrate the gel and raise\nthe internal temperature sufficiently to initiate significant evaporation. Therefore, the\n“desorption onset” is effectively immediate for our internal heating design, while it\nis significantly delayed in the surface heating case, providing clear, kinetic evidence\nfor the superiority of the heterogeneous architecture. These clarifications, supported by\nboth kinetic data and direct thermal imaging, will be integrated into the manuscript to\nstrengthen our argument.\nFig. R4 a, Surface temperature variations of fully hydrated HPGP under different solar illumination.\nb, Variation in the average mass of fully hydrated HPGP under different solar illumination. c,\nSurface temperature and average mass variations of heterogeneous structure and homogeneous\nstructure under 1.0 sun illumination. Data are presented as the mean ± standard deviation from five\nindependent experiments.\nThe changes are highlighted in blue in the revised manuscript.\nIn the Solar-driven water desorption performance of HPGP section (Page 18, Line 6-\n18, 20-23):\n“Fig. 5d and Supplementary Fig. 35 illustrate two distinct thermal transport\ndynamics, demonstrating the superiority of the internal heating mode in HPGP over the\nconventional surface heating of homogeneous structure. The homogeneous structure,\nwith its evenly dispersed GO, concentrates heat generation at the top surface. This\ncreates a thermal bottleneck and an inefficient outside to inside thermal gradient, where\nheat must slowly conduct through the pectin hydrogel matrix, leading to significant\nsurface energy loss and a delayed thermal response. In stark contrast, the heterogeneous\narchitecture of HPGP enables an efficient inside to outside heating mode. As directly\nconfirmed by thermal imaging, its centrally located GO interlayers act as a dedicated\ninternal heat source. This internal heating mechanism minimizes surface losses and\nensures efficient inside to outside heat diffusion, delivering thermal energy directly to\nthe stored water and thus accelerating the overall temperature rise. This fundamental\ndifference in heat management directly accounts for the enhanced desorption kinetics\nobserved.”\n“Critically, Fig. 5f shows that the internal heating design has a nearly\ninstantaneous desorption onset, characterized by an immediate, steep mass loss. The\nhomogeneous structure, however, exhibits a significant thermal lag period with minimal\nmass change before effective desorption begins.”\nComment 7:\nThe outdoor experiment lasts for 3 days, but the ambient conditions in Figure 6c only\nshows 1 day. In addition, the daily water productivity various a lot during the 3 days,\nbut no discussion is provided on it; at least the correspond weather conditions or other\nrelevant details should be provided. Also, averaging the 3-day water productivity is not\nscientific and has no meaning to directly compare with other work.\nResponse to comment 7:\nThank you for your sharp observation regarding the outdoor experimental data. We\nagree that our initial presentation of the 3-day outdoor experiment was not sufficiently\nclear. The variation in daily water production is not a sign of inconsistent performance,\nbut rather a direct demonstration of the HPGP’s high water uptake capacity and its\nability to continuously adsorb moisture over an extended period. Our material is\ndesigned for large-capacity, multi-day cycles, especially in environments where\nconditions for full desorption (i.e., strong, consistent sunlight) may not occur daily.\nTo clarify the point about Figure 6c, you are correct that the data as presented was\nnot representative of the dynamic conditions. In our initial attempt to condense the\ninformation, we had averaged the temperature and humidity data over the three-day\nperiod. We now understand that this was a misleading approach because it obscured the\nday-to-day environmental fluctuations that are essential for interpreting the material’s\nperformance. As you rightly suggest, the solution is to present the complete,\nunadulterated data. Therefore, we have supplemented the data for Figure 6c, showing\nthe complete and continuous 72-hour temperature and humidity curves in the\nsupporting information (Supplementary Fig. 41).\nRegarding the second question, the reviewer is absolutely correct that averaging\nwater productivity over three days with varying conditions is not a scientifically sound\nmethod for comparison. To clarify, the daily water productivity of 2.86 L kg-1 day-1\nreported in our work was calculated based solely on the data from the first day of the\noutdoor experiment, which corresponded to the ambient conditions shown in Figure\n6c. We presented the results from the subsequent two days to demonstrate the stable\nperformance of the device over a longer period under real-world conditions. We have\nnow revised the manuscript to state this explicitly and prevent any ambiguity.\nThe changes are highlighted in blue in the revised manuscript and Supporting\ninformation.\nIn the Demonstration of the outdoor water-harvesting tests section (Page 21, Line 13-\n15, 18-20):\n“Figure 6c shows average changes in ambient temperature and relative humidity\nduring the three-day experiment.”\n“Based on the first-day water production, the sorbent achieved a remarkable\nfreshwater productivity of 2.86 L kg -1day-1, a value that surpasses most leading\nwater sorbent\nsorbents developed for SAWH systems (Fig. 6g and Supplementary Table 7)\n19,27,38,18,39,30,40–42.”\nIn the Supporting information section:\n“Note 5: In order to study the operational characteristics of HPGP-based\nequipment in a continuous real-world environment, an outdoor experiment was\ndeployed for three consecutive days. The ambient conditions, as detailed in Fig.41,\nremained generally favorable for atmospheric water harvesting throughout the test\nperiod, without drastic degradation from one day to the next. As the number of sorption\ndays increases, the sample gradually reaches sorption saturation. The observed daily\nwater yields were 5.215 g (Day 1), 2.173 g (Day 2), and 0.815 g (Day 3).”\nSupplementary Fig. 41 Temperature and humidity data from three days of outdoor experiments,\nalong with the final average temperature and humidity changes.\nComment 8:\nWhy the sorbed mass in outdoor experiment is more than that in laboratory experiment\nfrom Figure S30 under the same conditions?\nResponse to comment 8:\nWe appreciate the reviewer’s valuable feedback. The original comparison between\noutdoor and laboratory conditions was indeed imprecise. We have now revised the\nmanuscript to correct this and provide a clearer explanation.\nOur standard laboratory performance tests were conducted under constant,\ncontrolled conditions of 25 °C and 60% RH. In contrast, the outdoor experiment\ninvolved a dynamic diurnal cycle. As shown in the environmental data in Fig. 6c, while\nthe average daytime temperature was around 25 °C, the critical nighttime sorption\nphase occurred at lower temperatures where the relative humidity frequently exceeded\n80%.\nThe hygroscopic uptake of our HPGP material is highly dependent on the ambient\nrelative humidity, a characteristic behavior detailed in our sorption isotherm\n(Supplementary Fig. 20). This figure clearly shows that the material’s water uptake\ncapacity at RH > 80% is substantially greater than its capacity at a constant 60% RH.\nTherefore, the higher total sorbed mass observed in the outdoor experiment is the direct\nand expected result of the sorbent being exposed to the significantly more favorable\nhigh-humidity conditions during the night. This allowed the material to capture a far\ngreater amount of water than what is achievable under the less humid, static 60% RH\nlaboratory protocol (Supplementary Fig. 46). We have corrected this error in the\nmanuscript to accurately reflect the experimental conditions and have clarified this\npoint in Supplementary Note 7 and in the caption for what is now Supplementary Fig.46.\nFig. 6c Variations in average environmental temperature and humidity during the outdoor water-\nharvesting tests.\nSupplementary Fig. 20 Water sorption capacity of HPGP at different relative humidity conditions\nranging from 30% to 90%.\nSupplementary Fig. 46 Comparison of sampling rates between laboratory conditions and outdoor\nconditions.\nThe changes are highlighted in blue in the Supporting information.\nIn the Supporting information:\n“Fig.46 Comparison of the sorbent’s water uptake performance in a controlled\nlaboratory setting versus a real-world outdoor environment. The laboratory test was\nconducted under static conditions of 25 °C and 60% RH. The nocturnal sorption phase\nin the outdoor test occurs under much higher relative humidity conditions\n(typically >80%, as shown in the main Figure 6c), which explains the significantly\nhigher water uptake observed compared to the static 60% RH laboratory test.”\n“It is important to note that a direct comparison between the static laboratory\nsorption tests and the dynamic outdoor experiments requires careful consideration of\nthe environmental conditions. Our laboratory isotherms were measured under fixed\ntemperature and relative humidity (25 °C, 60%RH) values to establish baseline material\nproperties. However, the outdoor performance is governed by a continuous diurnal\ncycle. As shown in Figure 6c, the nighttime sorption phase benefits from elevated RH\nlevels (often >80%) that are significantly higher than the 60% RH condition used for\nsome standard lab comparisons. As the material’s sorption capacity is strongly and\npositively correlated with RH (Fig.20), the greater water uptake observed outdoors is a\ndirect consequence of these more favorable high-humidity nighttime conditions, rather\nthan an inconsistency in the material’s performance.”\nReviewer #3\nGeneral Comment:\nThe manuscript (NCOMMS-25-72438-T) presents heterogeneous hygroscopic gels for\natmospheric water harvesting with seemingly impressive performance metrics, but\nthere are substantial concerns regarding the novelty of the approach, the robustness of\nthe main conclusions, and the practical scalability of the material. Moreover, significant\nadditional experiments are required to support the authors’ claims. Given the scope of\nthese issues, I recommend rejection in its current form.\nOur responses to the comments and suggestions from Reviewer #3\nWe sincerely thank reviewer #3 for their valuable feedback and for recognizing the core\nconcept of our work. We have carefully considered the reviewer’s primary concerns\nregarding the novelty, robustness, and scalability of our work. In response, we have\nconducted a comprehensive suite of new experiments designed to provide unequivocal,\nquantitative support for our central claims. The new data, which includes XRD,\nlow-field NMR, and extensive material stability and water quality analyses, now provides a\nmuch deeper mechanistic insight and practical validation that we believe addresses all\npoints raised.\nThe central novelty of this work is the design of a heterogeneous structure that\nspatially decouples the thermodynamic process of vapor sorption from the kinetic\nprocess of liquid water transport. This is a fundamental departure from conventional\nhomogeneous structure, where these two functions are inherently coupled within a\nsingle homogeneous matrix, leading to a performance trade-off. The core strategy\nmaterializes the concept of asymmetric hydrophilicity-driven fast water diffusion by\nestablishing a localized hydrophilicity gradient. This is achieved by interfacing a super-\nhygroscopic pectin-glycerol capture layer with a network of relatively hydrophobic\ngraphene oxide nanochannels, which serve as a low-resistance transport pathway,\nthereby enabling rapid water diffusion.\nThis asymmetric hydrophilicity-driven fast water diffusion creates a directed,\nhigh-flux pathway for water, which is mechanistically distinct from homogeneous\nhydrophilic networks. We have now provided direct experimental proof for this\nmechanism. XRD data reveals a dynamic expansion of the GO interlayer spacing upon\nhydration, confirming the activation of these nanochannels as physical conduits for\nwater. Crucially, low-field NMR spectroscopy analysis quantitatively differentiates\nbetween the intermediate water state within the hygroscopic capture layer and the free,\nmobile water within the transport channels. The results clearly show a rapid saturation\nof the bound state followed by a dominant and sustained increase in the free water signal,\ndirectly validating the proposed water transfer process.\nTo address the robustness of our conclusions, we have performed critical stability\nand performance tests. Raman spectroscopy data confirms the chemical integrity of\nthe GO framework remains unchanged after repeated hygroscopic cycles. A key\npractical concern with such gels is component leakage. We have now performed a\nrigorous analysis of the harvested water using ICP-MS, GC-MS, and TOC\nmeasurements. These highly sensitive tests show negligible organic or ionic content,\nconfirming the high stability of the crosslinked pectin-glycerol matrix and the purity of\nthe collected water. Furthermore, to demonstrate real-world applicability and move\nbeyond controlled laboratory conditions, we have included outdoor atmospheric\nwater harvesting results from dynamic, real-world environments. These field tests\nvalidate our laboratory findings and demonstrate effective performance under\nfluctuating conditions. Regarding scalability, our layer-by-layer fabrication relies on\nwell-established and repeatable coating and solution immersion techniques. The\nscalability is now supported by new data showing excellent batch-to-batch\nreproducibility of the material’s structure and hygroscopic performance, which is the\nfoundational requirement for any scalable manufacturing process. We are confident that\nthis substantial body of new experimental evidence provides the necessary support for\nour claims and transforms the manuscript into a complete and robust scientific\ncontribution.\nAccording to your meaningful comments, the point-to-point responses according\nto your kind suggestions have been addressed substantially in the revised version of our\nmanuscript and are marked by giving the text a blue color. We hope our revised version\ncan be accepted by Nature Communications.\nComment 1:\nThe concept of using GO and pectin in a layered structure, while interesting, does not\nrepresent a significant conceptual leap from existing hygroscopic composites. The\nauthors should provide a more rigorous comparison with previously reported\nheterogeneous or multi-layered hydrogel/organogel systems (e.g., GO-cellulose,\nGO-alginate, etc.) to clearly establish the novelty of their design.\nResponse to comment 1:\nWe sincerely thank the reviewer for this constructive suggestion. We agree that a\nrigorous comparison with previously reported heterogeneous and multi-layered systems\nis crucial to contextualize the novelty and superiority of our design. To address this,\nwe have substantially revised the manuscript to include a detailed comparative analysis.\nThis analysis not only contrasts our work with simple homogeneous blends but also\nbenchmarks it against the state-of-the-art structural designs in the field, including\nAligned Hierarchical, Unidirectional, Pore-engineered, Microsphere-based, and\nJanus structures, many of which utilize materials like cellulose and sodium alginate.\nAs shown in Table 3 and Supplementary Fig. 24, our material consistently exhibits a\nhigher water sorption capacity than prominent benchmark materials. This superior\nperformance is a direct result of the fundamental advantages offered by our\n“asymmetric hydrophilicity-driven decoupling” design.\nOur approach is conceptually distinct from other advanced architectures. While\ndesigns such as pore-engineered or aligned structures attempt to optimize transport by\ncreating predefined pathways, they do so within a single, swellable hygroscopic matrix\nand thus remain fundamentally limited by the material’s intrinsic diffusion resistance.\nIn stark contrast, our superior performance is achieved through a macro-level\nheterogeneous design concept without resorting to such complex microstructural\nengineering. We have not performed any modifications like pore etching, chemical\ngrafting, or forced alignment within the GO transport layer. Instead, the remarkable\nperformance stems directly from our macro-level heterogeneous design concept—the\nstrategic lamination of two materials with a sharp, engineered hydrophilic gradient. The\nfact that this relatively simple, scalable fabrication method yields results superior to\nmore intricate micro-engineered systems powerfully validates the effectiveness and\nelegance of our core design principle.\nSupplementary Table. 3 Comparison of water sorption capacity of different structural\ndesign.\nSorbent Sorption water capacity Main Structural\nReference\nmaterials (RH) Components Design\n1.6–2.5–6.2 g g−1 (RH30–60– Allgned\nBHNC GO, Alginate\n20\n90%) hierarchical\nPCC20@LiCl- 3 0.99–5.43 g g−1 (RH20–80%) CNT, Cellulose Unidirectional 51\n0.37-1.07-1.55 g g−1 (RH30–\nMMPA PPy, Alginate Unidirectional\n29\n50–90%)\n1.4–3.1–5.6 g g−1(RH30–60–\nBina/FCNT CNT, Alginate Microspheres\n63\n90%)\nCarbon black,\nSA/HPC/CB/Ur 0.64–1.26–3.38 g g−1(RH30–\nAlginate, Microspheres\n64\nea@CaCl 60–90%) 2\nCellulose\nGraphene,\nNBHA 0.3–2.36 g g−1 (RH35–95%) Nanostructured 43\nCellulose\n0.74-1.44-3.45 g g−1 (RH30–\nDBJA PPy, HPC Janus 32\n50–90%)\nMelamine\nCS/SA/CMC@ 1.2–2.8–3.9 g g−1 (RH30–60–\nfoam, Alginate, Pore\nCellulose\nGO/SA/LiCl\n1.92 g g−1 (RH80%) GO, Alginate Homogeneous 65\nhydrogel\n0.83–2.97–6.57 g g−1(RH30–\nHPGP (This\nGO, Pectin Heterogeneous\nwork) 60–90%)\nSupplementary Fig. 24 Comparison of moisture sorption capacity of different sorbent materials.\nThis engineered disparity in hydrophilicity drives the core mechanism of our\nHPGP. The outer pectin layer acts as a high-efficiency capture zone, rapidly condensing\natmospheric vapor into liquid. Subsequently, this difference in water affinity, further\namplified by glycerol, generates a powerful chemical potential gradient that actively\n“pumps” the captured liquid from the pectin interface into the GO interlayers for rapid\ndiffusion and storage. This mechanism is directly supported by our molecular dynamics\n(MD) simulations, which confirm high-velocity water diffusion along the GO\nnanosheets—a diffusion coefficient significantly higher than that in comparable\nhomogeneous materials. This asymmetric hydrophilic design creates an unobstructed\npathway for water molecules, providing a solution to the contradiction between rapid\ncapture and slow transmission faced by traditional moisture-absorbing materials. By\nspatially decoupling these two functions, it synergistically enhances adsorption\ncapacity and diffusion kinetics, thereby improving the water collection performance of\nthe material.\nFurthermore, the selection of pectin was an evidence-based choice critical to\nrealizing this asymmetric concept. Our comparative study (Supplementary Fig. 8)\nreveals that pectin possesses a superior combination of properties. Its exceptional\nhygroscopicity enables gas-to-liquid conversion and the formation of visible water\ndroplets in just 11 minutes—a rate significantly faster than that of sodium alginate (50\nminutes). This rapid capture ability is critical for establishing the strong concentration\ngradient that drives subsequent transport. Moreover, unlike materials such as PVA and\nKGM which failed to form stable films, pectin’s excellent film-forming capability\nensures the creation of a uniform, discrete surface layer. This processability is key to\nachieving true physical separation between the capture and transport zones, thereby\npreventing the polymer from intercalating into and obstructing the GO nanochannels.\nTherefore, the combination of pectin’s superior kinetics and ideal processing\ncharacteristics makes our novel asymmetric design possible, leading to a synergistic\nenhancement of the material’s overall water-harvesting performance.\nSupplementary Fig. 8 Comparison of gas-liquid conversion capacity of different material surfaces.\na, Pectin exhibits water droplets within 11 minutes. b, Sodium alginate (SA) exhibits water droplets\nwithin 50 minutes. c, Polyvinyl alcohol (PVA) does not form a film after being soaked in glycerin.\nd, Konjac glucomannan (KGM) does not form a film after being soaked in glycerin.\nThe changes are highlighted in blue in the revised manuscript.\nIn the Introduction section (Page 4, Line 6-23):\n“Here we propose a new strategy to construct heterogeneous structure composed\nof pectin-graphene oxide (GO)-pectin-based hygroscopic organogel (HPGP) uniformly\ninfused with glycerol, with high sorption capacity and rapid desorption rates. This\nstructure achieves spatial decoupling of water capture and transport. The outer pectin-\nglycerol layers provide the thermodynamic driving force for vapor liquefaction via a\nstrong osmotic gradient, while the central GO interlayers establish a kinetic pathway to\nsustain the process. Acting as a low-friction internal transport network, GO interlayers\nprevent surface saturation by rapidly channeling condensed water into the material’s\ncore. This spatial decoupling prevents the captured water molecules from being overly\nimmobilized by hydrogen bonds at the surface, thereby sustaining the high efficiency\nof the glycerol-driven osmotic pump. Additionally, the central GO interlayers exhibit a\nstrong photothermal response and enable solar-driven water release, significantly\nboosting the overall desorption efficiency. As a result, HPGP achieves a high sorption\ncapacity, ranging from 0.83 to 6.57 g g-1 at relative humidities of 30% to 90%; under\n1.0 sun illumination, the desorption rate was up to 2.06 kg m-2 h-1, and more than 90%\nof the water was desorbed within 40 min. These features enable a HPGP-based SAWH\ndevice to produce up to 2.86 L kg -1day-1, representing a performance highly\nwater sorbent\ncompetitive with the leading reported SAWH systems. This work provides valuable\ninsights into designing high-performance sorbent materials and highlights a promising\nstrategy to enhance moisture sorption-desorption performance in SAWH applications.”\nIn the Sorption capacity of HPGP section (Page 15, Line 14-16):\n“Consequently, HPGP surpasses most previously reported high-performance and\ndifferent structural design sorbent materials in moisture sorption capacity (Fig. 4f,\nSupplementary Figs. 24, 25 and Supplementary Tables. 2, 3) 8,10,23–28,19,29–31.”\nComment 2:\nThe proposed “asymmetric hydrophilicity-driven fast water diffusion” is primarily\nsupported by MD simulations, which are limited in scale and realism. Experimental\nevidence, such as in-situ Raman or NMR spectroscopy, is needed to directly observe\nand quantify water transport pathways and dynamics within the heterogeneous structure.\nResponse to comment 2:\nWe thank the reviewer for this insightful suggestion. To experimentally validate the\nasymmetric diffusion mechanism predicted by our molecular dynamics simulations, we\nhave conducted low-field nuclear magnetic resonance (LF-NMR) T relaxation\n2\nexperiments. This technology non-destructively differentiates water populations based\non molecular mobility, classifying them according to their relaxation times: 0.1–10 ms\nfor bound water, 10–100 ms for intermediate water, and >100 ms for free water (Fig.\nR5). We analyzed three key sample groups: the HPGP at different hydration levels\n(initial, 30% RH, and 90% RH), and two control samples—pure glycerol-intercalated\npectin and pure glycerol-intercalated GO—both analyzed at initial and 90% RH\nconditions.\nFig. R5 The distribution of water molecules among the states of bound, intermediate, and free water\nmolecules of hydrogel.\nThe results, as detailed below and shown in the T relaxation spectra\n2\n(Supplementary Fig. 13), provide direct and compelling experimental support for our\nproposed mechanism.\n1) HPGP (Heterogeneous Structure) Confirms the Multi-State Water Sorption\nProcess (Supplementary Fig. 13d)\nAt 30% RH, the T spectrum of HPGP is dominated by peaks at very short\n2\nrelaxation times (<10 ms). This is the classic signature of bound water, confirming our\nhypothesis that initial water uptake involves strong immobilization via hydrogen\nbonding within the highly hydrophilic pectin layers.\nAt 90% RH, a dramatic change is observed. While the bound water peaks remain,\na new, distinct, and substantial peak emerges at a much longer T relaxation time (>100\n2\nms). This peak is the unambiguous signature of free water. This directly demonstrates\nthat once the primary binding sites in the pectin are saturated, excess water transitions\ninto a high-mobility state, which, according to our model, resides within the GO\ninterlayer channels. This two-stage appearance of distinct water populations strongly\nsupports the proposed decoupling of water capture (binding) and transport (free).\n2) Control Experiments Clarify the Roles of Pectin and GO (Supplementary Fig.\n13a, b)\nTo further prove the spatial decoupling of these functions, we analyzed the\ncomponents separately:\nGlycerol-Pectin: The Glycerol-Pectin matrix already displays a prominent T\n2\npeak in the intermediate range (10–100 ms). This signal is primarily attributed to the\nliquid glycerol itself, which is intercalated within the pectin network, forming a baseline\nfluidic system. Upon hydration to 90% RH, a critical phenomenon is observed. Instead\nof creating a more mobile phase, the influx of water molecules forms strong hydrogen\nbonds with both pectin and glycerol, creating a highly viscous ternary hydrogel. This is\nevidenced by the fact that the T peak does not shift to longer times; instead, it remains\n2\nwithin the intermediate range, signifying that the overall molecular mobility is severely\nrestricted by the swollen polymer network. This result demonstrates the inherent\nlimitation of a purely hygroscopic polymer system: while it has high capacity, it traps\nwater in a high-viscosity, gel-like state, thus impeding rapid transport.\nGlycerol-GO Interlayers: In stark contrast, the hydrated GO-only sample’s\nsignal is centered primarily in the intermediate range but with limited free water\ncharacter, indicating that atmospheric moisture merely wets the graphene surfaces\nwithout filling the nanocapillaries to a bulk state. This proves that without the pump\neffect of the pectin reservoir, the GO channels cannot achieve their full transport\npotential.\n3) Dynamic Water Exchange Validates Interconnectivity\nAn even more subtle but powerful piece of evidence comes from the evolution of\nthe bound water peaks. As the system hydrates from 30% to 90% RH, the peak\ncorresponding to weakly bound water (~10 ms) in HPGP actually decreases in\namplitude, while the free water peak grows enormously. This phenomenon is a hallmark\nof dynamic exchange between water populations. It indicates that the bound water in\nthe pectin layers is not isolated but is in rapid exchange with the free water in the GO\nchannels. This confirms the seamless and efficient transfer of water from the capture\nsites to the transport network, which forms the basis of our asymmetric diffusion\nmechanism.\nIn summary, the LF-NMR results provide a multi-faceted experimental validation\nof our proposed mechanism (Supplementary Fig. 13). They not only distinguish and\nquantify the existence of both bound and free water but also, through the analysis of the\ncomplete HPGP and its individual components, spatially assign the roles of water\ncapture to the pectin shell and rapid transport to the GO interlayers. The evidence of\ndynamic exchange further confirms the efficient coupling between these two functions.\nThis body of experimental data is in excellent agreement with our simulation results\nand supports the central claims of our manuscript.\nBy integrating our computational and experimental findings, we can draw a\ncohesive and strongly supported conclusion. The LF-NMR results provide direct\nexperimental proof of the existence of two distinct water populations—bound and\nfree—within the HPGP material, with the free water population emerging at high\nhydration levels. This aligns perfectly with the insights from our MD simulations. As\nstated in our manuscript: “Our analysis (Fig. 3d, e and Supplementary Fig. 12) shows\nthat the diffusion coefficient D of water molecules in heterogeneous structure is\napproximately 204.03, significantly higher than that in homogeneous structure (around\n181.16).” The high-velocity diffusion pathway predicted by the simulations is the\nmicroscopic origin of the highly mobile free water population detected by LF-NMR.\nThus, the synergy between direct experimental observation and atomistic simulation\nprovides compelling validation for our “asymmetric hydrophilicity-driven decoupling\ndesign.” The LF-NMR data confirms what is happening (the existence of two water\nstates), while the MD simulations explain why it is happening (the creation of low-\nfriction GO nanochannels). This combined evidence provides strong support for our\nhypothesis that the spatial decoupling of water capture (bound water in pectin) and\ntransport (free water in GO) effectively mitigates the inherent trade-off between\nsorption capacity and diffusion kinetics in hygroscopic materials.\nSupplementary Fig. 13 a, Low-field NMR tests of Glycerol-Pectin under different hydration levels\n(original and 90% RH). b, Low-field NMR tests of Glycerol-GO interlayers under different\nhydration levels (original and 90% RH). c, Low-field NMR tests of HPGP under different hydration\nlevels (original, 30% RH, and 90% RH). d, Low-field NMR tests of HPGP, Glycerol-Pectin and\nGlycerol-GO interlayers under 90% RH.\nFig. 3 Mechanism for continuous and high-capacity moisture sorption of the HPGP. a, i. Glycerol\nmolecules carry water molecules into the HPGP interior using osmotic pressure. ii. Water molecules\nreplace glycerol molecules bound to the GO interlayers in the form of hydrogen bonds, completing\nthe fixation of water molecules on the GO interlayers. b, The migration of water molecules within\nheterogeneous structure. c, The migration of water molecules within homogeneous structure. d, The\nMSD-t curve of water molecule migration in heterogeneous structure. e, The MSD-t curve of water\nmolecule migration in homogeneous structure. f, Low-field NMR tests of HPGP under different\nhydration levels (original, 30% RH, and 90% RH).\nThe changes are highlighted in blue in the revised manuscript and supporting\ninformation.\nIn the Mechanism for continuous and high-capacity moisture sorption of the HPGP\nsection (Page 10,11, Line 19-23, 1-9):\n“To experimentally validate this simulation-predicted high-mobility state, LF-\nNMR measurements were performed. The results reveal a critical humidity-dependent\ntransition facilitated by this specific structure (Fig. 3f). At low humidity (30% RH), the\nspectrum is dominated by bound and intermediate water signals, confirming the role of\nthe outer pectin layers in initially capturing atmospheric moisture. Strikingly, at 90%\nRH, a distinct and substantial population of free water (>100 ms) emerges. This\nbehavior contrasts sharply with the control experiments on individual components\n(Supplementary Note 2 and Supplementary Fig. 13). While pure pectin primarily\nconstrains water within the intermediate range and pure GO exhibits signals\ncharacteristic of surface-interacting water, the HPGP demonstrates a clear structural\nsynergy. The hygroscopic pectin coating acts as a saturated reservoir, effectively\npumping captured moisture into the GO interlayers. This ensures the graphene\nnanocapillaries are fully flooded, allowing water to transition from a surface-bound\nstate to a highly mobile, bulk-like fluid state. This direct observation confirms that the\nheterogeneous structure not only captures water but effectively activates high-speed\ntransport channels.”\nIn the supporting information:\n“Note 2: To elucidate the molecular-level water transport mechanism within the\nHPGP structure, we employed low-field nuclear magnetic resonance (LF-NMR)\nrelaxometry, which probes the mobility of water protons via their transverse relaxation\ntime (T ). Shorter T values (<10 ms) correspond to motion-restricted bound water,\n2 2\nwhile longer values (>100 ms) signify highly mobile free water. We first established\nbaseline assignments using control experiments on the individual components (Fig. 13).\nWe first established baseline assignments using control experiments (Fig. 13a).\nThe Glycerol-Pectin matrix already displays a prominent T peak in the intermediate\n2\nrange (10–100 ms). This signal is primarily attributed to the liquid glycerol itself, which\nis intercalated within the pectin network, forming a baseline fluidic system. Upon\nhydration to 90% RH, a critical phenomenon is observed. Instead of creating a more\nmobile phase, the influx of water molecules forms strong hydrogen bonds with both\npectin and glycerol, creating a highly viscous ternary hydrogel. This is evidenced by\nthe fact that the T peak does not shift to longer times; instead, it remains within the\n2\nintermediate range, signifying that the overall molecular mobility is severely restricted\nby the swollen polymer network. This result powerfully demonstrates the inherent\nlimitation of a purely hygroscopic polymer system: while it has high capacity, it traps\nwater in a high-viscosity, gel-like state, thus impeding rapid transport.\nConversely, Glycerol-GO interlayers also exhibit a signal centered primarily in the\nintermediate range but with lower amplitude and limited free water character. This\nindicates that without the driving force of an external reservoir, atmospheric moisture\nmerely wets the graphene surfaces and forms hydration layers, without filling the\nnanocapillaries to a bulk state.\nBuilding on these baselines, the HPGP structure reveals a transformative synergy.\nAt low humidity (30% RH), the spectrum resembles the pectin control, confirming\ninitial uptake is driven by the coating. However, at 90% RH, a dramatic evolution\noccurs. A distinct, high-amplitude free water peak (>100 ms) emerges, which is\nphysically distinct from the constrained “swollen water” observed in the pure pectin\ncontrol. This implies a reservoir-to-channel mechanism: the pectin layer captures\nmoisture into its hydrogel network, but instead of stagnating in this restricted state, the\nwater is effectively pumped into the low-friction GO interlayers. This transition\nconverts semi-constrained moisture into a high-speed, bulk-like fluid, validating the\nasymmetric diffusion mechanism proposed in our simulations.”\nComment 3:\nThe authors claim that glycerol does not evaporate during solar desorption based on\nFTIR of evaporated gas. This is insufficient. Long-term cycling tests under realistic\noutdoor conditions with quantitative analysis of glycerol loss (e.g., via HPLC or GC-\nMS) are necessary to validate the material's durability.\nResponse to comment 3:\nWe appreciate the insightful feedback from the reviewer regarding the long-term\nstability and potential loss of glycerol, which is a critical aspect of the practical\napplication of the material. The suggestion to employ a more quantitative and sensitive\ntechnique is well-taken. In response to this valid point, we have conducted further\nexperiments to rigorously assess the stability of glycerol within our system during\nthe solar desorption process. To achieve this, we conducted an extended durability\ntest for 45 consecutive days of adsorption-desorption cycles. The samples maintained\nmorphological stability and consistent moisture absorption effects before and after the\nhygroscopic cycles (Supplementary Fig. 53). Following this long-term cycling, we\ncollected the produced water from the solar desorption process and analyzed it using\nGas Chromatography-Mass Spectrometry (GC-MS), a highly sensitive method for\ndetecting trace organic compounds. The GC-MS results show no characteristic peaks\ncorresponding to glycerol or its thermal decomposition products (Supplementary\nFigs. 48-50). The primary components detected were residual atmospheric gases such\nas oxygen and carbon monoxide. The absence of a glycerol signal in the GC-MS\nanalysis provides direct evidence that glycerol remains stable and does not evaporate\nor decompose under the operational conditions of solar-driven desorption.\nTo properly incorporate this new evidence into the manuscript and address the\nreviewer’s concern, we have revised the relevant section. The original text has been\nupdated to include the methodology and findings from the GC-MS analysis.\nThe changes are highlighted in blue in the revised manuscript.\nIn the Demonstration of the outdoor water-harvesting tests section (Page 22, 23, Line\n9-20, 2-6):\n“The stability of internal glycerol and the purity of the desorption process were\nrigorously investigated. Analysis of the vapor phase via Fourier-transform infrared\nspectroscopy (FTIR) confirmed the absence of evaporated glycerol; specifically, while\nstrong absorption peaks corresponding to the O-H bonds of water were observed (3300–\n3800 cm-1), the characteristic C-H absorption peaks of glycerol (2500–3000 cm-1) were\nundetectable (Supplementary Fig. 47). This was further corroborated by gas\nchromatography-mass spectrometry (GC-MS), which revealed no molecular glycerol\nor its thermal decomposition byproducts in the gas phase, only residual atmospheric\ncomponents (Supplementary Figs. 48-50). Consequently, the harvested water exhibited\nexceptional purity. Its total organic carbon (TOC) level was minimal (<5 mg/L), on par\nwith deionized water, confirming no organic leaching. Moreover, inductively coupled\nplasma mass spectrometry (ICP-MS) analysis showed no zinc ion leakage and verified\nthat the water quality complies with World Health Organization (WHO) standards (Fig.\n6e).”\n“The results demonstrated that HPGP assembled with recycled GO interlayers\nretain excellent sorption and desorption performance, with minimal deviation across\nmultiple cycles, and the samples retained morphological stability before and after the\nhygroscopic cycle. (Fig. 6f and Supplementary Fig. 53).”\nSupplementary Fig. 53 Morphology before and after sample moisture sorption cycle.\nSupplementary Fig. 48 Chromatogram of the collected water.\nSupplementary Fig. 49 Chromatogram of the collected water.\nSupplementary Fig. 50 Chromatogram of the collected water.\nComment 4:\nThe water uptake of 0.83 g g⁻¹ at 30% RH is modest and not competitive with state-of-\nthe-art desiccant materials. The authors should compare their material with recent low-\nRH sorbents (e.g., MOFs, hygroscopic salts, or advanced hydrogels) to better\ncontextualize its performance.\nResponse to comment 4:\nWe thank the reviewer for their critical evaluation, which has prompted us to more\nprecisely define the optimal operating conditions and primary contributions of our work.\nWe agree that the water uptake at 30% RH is not record-setting when compared to\nsorbents specifically engineered for extreme arid conditions (e.g., certain MOFs or salt-\nbased composites). Our work was not intended to compete on this single metric, and\nwe acknowledge that our initial presentation may have created this ambiguity. Instead,\nour design philosophy prioritizes a unique and powerful combination of attributes\ntailored for a different, yet arguably broader and more practical, application\nscenario.\nThe strategic advantage of our HPGP sorbent lies not in extreme-RH performance,\nbut in its exceptional balance of high capacity, rapid kinetics, low-energy\nregeneration, and robust stability under the mid-to-high humidity conditions (RH >\n40%) that characterize the vast majority of the world’s populated regions. While some\nstate-of-the-art sorbents exhibit higher equilibrium capacities at low RH, they often face\ncritical trade-offs that limit their practical deployment. For instance, hygroscopic salts\nsuffer from deliquescence and leakage, compromising cyclability, while many MOFs\nrequire energy-intensive synthesis and regeneration. [1,2] The HPGP is specifically\nengineered to circumvent these issues, offering a scalable and durable solution for\nthe climates where most people live.\nFurthermore, we wish to emphasize that a core scientific contribution of our work\nis the development of an asymmetric hydrophilic structural design that\ndramatically enhances sorption/desorption kinetics. By strategically creating a\nhighly hydrophilic outer layer and a relatively less hydrophilic inner core, we engineer\na distinct vapor pressure gradient that actively pulls water molecules from the surface\ndeep into the material’s matrix. This design provides a new solution to the critical\ntransport challenge faced by traditional hydrogel adsorbents with homogeneous\nstructures. This strategy of using engineered hydrophilicity gradients to boost dynamic\nperformance holds broad relevance and can be applied to other liquid sorbent-based gel\nsystems. Therefore, our work’s primary value should be seen not just in achieving a\nspecific uptake value, but in providing a robust and scalable method to engineer a\nsuperior balance of capacity, kinetics, and stability, tailored for efficient water\nharvesting in the climates where most people live.\nTo provide a clearer perspective on the performance of the HPGP, we have now\nincluded a comparative table in the revised manuscript (Table.2). This table\nbenchmarks our HPGP sorbent against a range of representative state-of-the-art\nmaterials (including select MOFs, hygroscopic salt composites, and advanced\nhydrogels). This comparison will explicitly highlight that while our material may not\nlead in equilibrium capacity alone, its overall combination of good uptake, fast kinetics\nand low-energy regeneration makes it a highly competitive and promising candidate for\npractical solar-driven atmospheric water harvesting applications.\nThe changes are highlighted in blue in the Supporting information.\nSupplementary Table.2 Comparison of water sorption capacity of different sorbent\nmaterials.\nSalt\nSorbent materials Sorption water capacity (RH) under 25oC &Content Reference\n(%, wt)\n2.15–2.68–3.1 g g−1(RH70–80–90%) LiCl\nRFMP\n19\n(600-600-600min) (0.2g/mL)\n0.5–1–2.5 g g−1 (RH30–60–90%)\nSMCA PPy-Cl\n10\n(120-120-360min)\n0.5–1.15–1.5 g g−1 (RH30–60–90%) CaCl\nILCA\n2 5\n(240-180-1440min) (25)\n0.5–2.6–6 g g−1 (RH30–60–90%)\nPOG Glycerin\n1\n(120-600-1440min)\n0.75–1.2 g g−1 (RH 60–90%) LiCl\nCNTs-CILs@cotton rod\n6\n(300-300-600min) (30)\n0.68–1.61–2.76 g g−1 (RH30–60–90%) PPy-Cl\nPDA@PP-Cl Hydrogel\n12\n(1200-1200-1200min) (20)\nPAM–CS–MXene–LiCl 0.78–2.32–5 g g−1 (RH30–60–90%) LiCl\n11\naerogel (500-600-1800min) (4 mol/L)\n0.64–3.3 g g−1 (RH60–95%)\nPGF PAAS\n8\n(420-1440min)\n1.6–2.5–6.2 g g−1 (RH30–60–90%) LiCl\nBHNC\n20\n(120-360-NA min) (69)\n0.73–1.32–1.65 g g−1 (RH57–70–95%) LiCl\nBilayer scaffold-1.5\n3\n(NA-NA-700min) (2)\n1.623-4.601 g g−1 (RH60–90%) LiCl\nAgar /GG/PAM hydrogel\n7\n(240-360-1440min) (3 mol/L)\n0.90-1.93-3.91 g g−1 (RH30–60–88%) LiCl\nTCP-Li\n2\n(NA-NA-NA min) (35)\n0.25-0.4-0.75 g g−1 (RH30–60–80%) LiCl\nLiCl@MOF-303\n21\n(25-25-25min) (14.42)\n0.4-0.675 g g−1 (RH30–60%) LiCl\nLiCl@SiO\n22\n2\n(NA-NA min) (22.5)\n0.427-0.829-1.25 g g−1 (RH30–60–80%) LiCl\nLiCl@Al-fum\n23\n(50-50-NA min) (27.7)\n0.595-0.95-1.6 g g−1 (RH30–60–80%) LiCl\nLiCl@UIO-66\n24\n(400-400-600min) (30)\nLiCl@MIL- 0.3-0.65-0.95 g g−1 (RH30–60–80%) LiCl\n25\n101(Cr) (180-NA-NA min) (33)\n0.7-1.25-2.1 g g−1 (RH30–60–80%) LiCl\nLiCl@ SiO HS\n26\n2\n(150-NA-NA min) (39.5)\nLiCl@MIL- 0.9-1.6 g g−1 (RH30–60%) LiCl\n27\n100(Fe) (200-200min) (54.5)\n0.11–0.83–2.9 g g−1 (RH30–60–90%) CoCl\nCo-SHM\n2 28\n(NA-NA-NA min) (57.1)\n0.37-1.07-1.55 g g−1 (RH30–50–90%)\nMMPA MIL-101(Cr)\n29\n(NA-NA-NA min)\nLiCl@Activated 0.15-0.25-0.37 g g−1 (RH30–60–80%) LiCl\n30\nalumina (AL20) (NA-210-210min) (12.14)\n1.57-3.15 g g−1 (RH30–70%) LiCl\nXD87.50% -PP@LiCl\n31\n(120-120 min) (65)\n0.74-1.44-3.45 g g−1 (RH30–50–90%) LiCl\nDBJA\n32\n(600-1800-1200min) (52.63)\n1.2-2-5.2 g g−1 (RH30–50–90%) LiCl\nTHMPH\n33\n(240-360-900min) (50)\n0.91-1.26-1.82 g g−1 (RH30–50–70%) LiCl\nBPLHs\n34\n(NA-NA-NA min) (34)\n1.43-2.09-3.21 g g−1 (RH25–50–75%) LiCl\nLiCl@CCS aerogels\n35\n(120-120-240min) (6)\nPNIPAm-co- 0.56-1.35-3.78 g g−1 (RH25–50–90%) LiCl\n0.49-0.91-2.98 g g−1 (RH30–50–90%) LiCl\nSMPH\n37\n(300-300-600min) (33.56)\n0.86-1.5-2.18 g g−1 (RH15–30–60%) LiCl\nZHPC\n38\n(120-120-300min) (65)\n0.68-1.09-1.67 g g−1 (RH15–30–60%) LiCl\nZHBC\n38\n(120-120-300min) (54)\n1.2–2.8–3.9 g g−1 (RH30–60–90%)\nCS/SA/CMC@MF exh CS/SA/CMC\n39\n(600-900-1200min)\n1.21–2.15–4.44 g g−1 (RH30–60–90%)\nMOF-CT/PVA MOF-CT\n40\n(30-30-30min)\n1.64–2.65–4.21 g g−1 (RH30–60–80%) LiCl\nCPPY@LiCl\n41\n(200-240-400min) (85)\n1.4–2.53–5.71 g g−1 (RH30–60–90%) LiCl\nBC/SA/GO-LiCl\n42\n(180-240-360min) （50）\n0.3–2.36 g g−1 (RH35–95%) LiCl\nNHBA\n43\n(180-180min) （90）\n0.43-0.89-1.48 g g−1 (RH15–30–60%) LiCl\nPCP@LiCl\n44\n(50-75-150min) （46）\n1.01–2.03–6.83 g g−1 (RH30–60–90%) LiCl\nHIPG\n45\n(50-90-NA min) （54.3）\n1.41-2.46-4 g g−1 (RH30–60–80%) LiCl\nLiCl@PAM\n46\n(NA-NA-NA min) (50)\n1.79-2.93 g g−1 (RH30–60%) LiCl\nLiCl@ACFF\n47\n(150-240min) （90）\n1.18-4.69 g g−1 (RH30–90%) LiCl\nTOCNF/NaAlg/MOF 303\n48\n(720-720min) （70）\n0.25–0.45–0.6 g g−1 (RH20–60–80%)\nMTC MOF-303\n49\n(20-20-20min)\n0.78–1.35–2.08 g g−1 (RH30–70–90%) CaCl\nCaCl @MIL-101@BC-2\n2 50\n2\n(180-180-300min) (20)\n0.99–5.43 g g−1 (RH20–80%) LiCl\nPCC20@LiCl- 3\n51\n(240-540min) （3）\n0.7–0.97–1.5 g g−1 (RH30–60–90%) LiCl\nCASN-Li\n52\n(120-120-120min) （25）\n0.83–2.97–6.57 g g−1(RH30–60–90%)\nHPGP (This work) Glycerin\n(1200-2400-3600min)\nFig.24 Comparison of moisture sorption capacity of different sorbent materials.\nIn the Sorption capacity of HPGP section (Page 15, Line 14-16):\n“Consequently, HPGP surpasses most previously reported high-performance and\ndifferent structural design sorbent materials in moisture sorption capacity (Fig. 4f,\nSupplementary Figs. 24, 25 and Supplementary Tables. 2, 3) 8,10,23–28,19,29–31.”\n1. Wang, J. et al. Tillandsia‐Inspired Ultra‐Efficient Thermo‐Responsive Hygroscopic\nNanofibers for Solar‐Driven Atmospheric Water Harvesting. Adv. Mater. 37, 2408977\n(2025).\n2. Xu, J. et al. Efficient Solar‐Driven Water Harvesting from Arid Air with Metal–\nOrganic Frameworks Modified by Hygroscopic Salt. Angew. Chem. Int. Ed. 59, 5202–\n5210 (2020).\nComment 5:\nThe photothermal conversion efficiency of GO is well-known. The manuscript fails to\ndemonstrate how the HPGP structure enhances this property beyond what is expected\nfrom GO alone. Spectral reflectance and thermal imaging under controlled conditions\ncould be provided to substantiate claims of improved light trapping.\nResponse to comment 5:\nWe thank the reviewer for this insightful suggestion. To experimentally isolate the\ncontribution of the material’s morphology, we designed a specific control experiment.\nBy comparing the wrinkled HPGP against a flat counterpart (a ‘Pectin-flat GO\ninterlayers-Pectin’ film), we demonstrate that the wrinkled surface is the primary driver\nfor the observed enhancement in light absorption and photothermal performance.\nThe underlying physical mechanism for this improvement was quantified using\nUV-Vis-NIR spectroscopy. As shown in Supplementary Fig. 26, while the Pectin-flat\nGO interlayers-Pectin already demonstrated a high broadband solar absorbance of\n90.1%, the wrinkled HPGP structure achieved an exceptional 96.9%. This significant\n~7% increase is a direct consequence of the wrinkles functioning as an efficient light-\ntrapping structure. On a conventional flat surface, a notable fraction of incident light is\nimmediately lost to specular reflection. In contrast, the wrinkled HPGP’s randomly\noriented surface normals redirect incident photons. Instead of reflecting back into the\nenvironment, light striking a sloped surface is preferentially scattered deeper into\nadjacent wrinkle valleys. This initial suppression of reflective loss is critical. Once\ntrapped within this topography, the photons undergo multiple internal reflections,\ndramatically extending their optical path length within the absorbing GO medium. At\neach reflection, a portion of the light energy is absorbed, increasing the cumulative\nprobability of absorption toward unity. In essence, the wrinkled geometry transforms\nthe material into a more effective optical cavity, minimizing energy loss and\nmaximizing solar energy harvesting. [1,2]\nSupplementary Fig. 26 UV-Vis-NIR absorption characteristics of HPGP and Pectin-flat GO\ninterlayers-Pectin.\nTo directly visualize and quantify the impact of this enhanced absorption on\nthermal performance, we conducted thermal imaging under simulated solar irradiation.\nThe results demonstrate that under the same intensity conditions (1 sun, AM 1.5G),\nthe HPGP sample reached a higher steady-state temperature more quickly than the Pectin-\nflat GO interlayers-Pectin (Supplementary Fig. 33). As solar intensity increased (from\n0.7 sun to 1.6 sun), the HPGP sample also exhibited a higher steady-state temperature\n(Supplementary Figs. 28, 30 and 31). This enhanced heat generation directly correlates\nwith the increased solar absorbance previously discussed. The results confirm that the\nwrinkled morphology is not merely a passive surface feature but an active light-trapping\nstructure that significantly amplifies the photothermal conversion efficiency of the\nmaterial.\nSupplementary Fig. 33 Influence of wrinkles on the surface temperature of HPGP.\nSupplementary Fig. 28 Temperature changes of HPGP under different solar illuminations.\nSupplementary Fig. 31 Temperature changes of Pectin-flat GO interlayers-Pectin under different\nsolar illuminations.\nSupplementary Fig. 32 Comparison of the maximum surface temperature of HPGP and Pectin-flat\nGO interlayers-Pectin under different solar illuminations.\nThe changes are highlighted in blue in the revised manuscript.\nIn the Solar-driven water desorption performance of HPGP section (Page 16, 17, 18,\nLine 17-19, 1-3, 19-23, 1-4)：\n“To specifically isolate the contribution of the wrinkled topography to this high\nabsorbance, we compared HPGP with a flat control (pectin-flat GO interlayers-pectin).\nThe wrinkled HPGP achieved a solar absorbance of 96.9%, significantly surpassing the\n90.1% of the flat GO interlayers (Supplementary Fig. 26). The wrinkles act as optical\ncavities that trap light via multiple internal reflections, extending the optical path length\nto maximize solar absorption.”\n“Notably, the superior light-trapping capability of the wrinkled HPGP directly\ntranslates to enhanced thermal performance. Under different sun illumination, the\nsurface temperature of HPGP is consistently higher than that of pectin-flat GO\ninterlayers-pectin (Supplementary Figs. 28, 31 and 32). As indicated in Supplementary\nFigs. 33 and 34, under 1.0 sun illumination, the introduction of surface wrinkles\nincreases the steady-state surface temperature from 51.4 °C (for pectin-flat GO\ninterlayers-pectin) to 55.3 °C (for HPGP) and enhances the mass change rate from 0.75\nkg m-2 to 1.03 kg m-2. These findings confirm that the structural features of GO\ninterlayers play a crucial role in amplifying the photothermal and desorption\nperformance of HPGP.”\n1. Shin, H., Jeong, W. & Han, T. H. Maximizing light-to-heat conversion of Ti3C2Tx\nMXene metamaterials with wrinkled surfaces for artificial actuators. Nat. Commun. 15,\n10507 (2024).\n2. Fan, Z., Hwang, T., Lin, S., Chen, Y. & Wong, Z. J. Directional thermal emission and\ndisplay using pixelated non-imaging micro-optics. Nat. Commun. 15, 4544 (2024).\nComment 6:\nThe fabrication process involves multiple steps (layer-by-layer assembly, crosslinking,\nsolvent exchange) that are difficult to scale. The authors should discuss the\nreproducibility of the wrinkle structure, layer uniformity, and the feasibility of mass\nproduction.\nResponse to comment 6:\nThank you for this constructive comment. Based on the current manuscript and\nsupplementary information, we agree that the feasibility of the multi-step preparation\nprocess in terms of reproducibility and scalability needs to be more clearly elucidated.\nIn the revision, we will thoroughly explain the steps to ensure control over the wrinkled\nstructure and layer uniformity and the steps to transform the experimental procedure\ninto a continuous production process.\nFirst, concerning the reproducibility of the crucial wrinkle structure, we can\nconfirm its high consistency over extended periods. The formation of these wrinkles is\ngoverned by a well-understood physical mechanism: strain mismatch arising from the\niterative drying and differential shrinkage of the GO layers. The primary determinants\nof the wrinkle wavelength and amplitude are the material’s modulus and the final dry\nfilm thickness, which are directly controlled by the GO solution concentration and the\nnumber of deposition-drying cycles. Systematic experiments show that a four-layer\nstructure consistently forms the optimal wrinkle pattern. This conclusion is supported\nby the macroscopic images of samples prepared at different times from December 2022\nto the present, all of which exhibit a consistent wrinkle pattern (Supplementary Fig. 58).\nSimilarly, regarding layer uniformity, we have conducted rigorous quality control\nthroughout our research. Thickness measurements of the GO base films, also performed\non samples from different batches over the same extended timeframe, confirm excellent\nuniformity with minimal deviation (Supplementary Fig. 59). This consistency\nunderscores the robustness of our layer-by-layer assembly protocol, where controlled\nsolution spreading and drying steps ensure a uniform deposition process.\nSupplementary Fig. 58 From December 2022 to December 2025, the GO film has a stable wrinkle\nstructure.\nSupplementary Fig. 59 The GO film from December 2022 to December 2025 has a uniform\nthickness.\nFinally, we have carefully considered the feasibility of mass production and\nenvision a clear pathway to translate our laboratory-scale “spread-dry-repeat” method\ninto an industrially relevant, continuous process. The four-layer GO base film can be\nformed using established techniques such as spray/blade coating or slot-die coating,\ncoupled with a multi-zone hot-air drying system to perform the iterative deposition\ncycles. Following the formation of the base film, the surface pectin layers would be\napplied to both sides using a similar coating process. Subsequently, the\nfunctionalization steps can be adapted to an in-line configuration: the cross-linking\nwould occur in a short-residence-time anhydrous zinc acetate bath, and the final\nglycerol solvent exchange could be managed in a counter-current washing cascade to\nenhance throughput and reduce solvent consumption.\nIt is important to highlight that all the aforementioned steps—coating, multi-zone\ndrying, and immersion baths—are standard unit operations within the membrane and\ncoating industries. Key process parameters such as coating speed, drying temperature\nand humidity, and residence time can be precisely controlled to replicate the thermal\nhistory and layering effect achieved in our lab (e.g., each layer of GO film is dried in\nan oven at 75 °C for 75 minutes. After coating with a pectin layer, it is crosslinked in a\nzinc acetate solution for 10 minutes. Solvent replacement is carried out in glycerol for\n24 hours). To ensure quality assurance in a scaled-up process, in-line metrology tools—\nsuch as mass-per-area sensors, and optical texture analysis for wrinkle statistics—can\nprovide closed-loop feedback for process control.\nGiven that our entire process utilizes aqueous solutions, operates at ambient or\nmild temperatures, and requires no high-vacuum or cleanroom facilities, we are\nconfident that scaling this fabrication from centimeter-sized lab samples to meter-scale\nroll-to-roll production is engineeringly feasible. While we refrain from adding new\nscale-up data in the current manuscript to maintain focus, we have supplemented the\nmethods section with more explicit process parameters and quality control metrics. This\nwill ensure that our peers can readily replicate the material’s unique morphology and\nhigh performance under equivalent conditions.\nSupplementary Fig. 57 Simulated large-scale factory preparation process for HPGP.\nThe changes are highlighted in blue in the revised manuscript and Supporting\ninformation.\nIn the Demonstration of the outdoor water-harvesting tests section (Page 23, 24, Line\n19-23, 1-8):\n“Looking beyond the proof-of-concept demonstration, we project a clear path for\nthe HPGP organogel toward practical application, built upon three pillars: economic\nviability, scalability, and sustainability. Based on low-cost, abundant materials (pectin,\ngraphite, glycerol, anhydrous zinc acetate), the system ensures its economic feasibility.\nMeanwhile, its ambient, water-based synthesis is fundamentally compatible with\nscalable, continuous manufacturing techniques like roll-to-roll processing\n(Supplementary Fig. 57 and Supplementary Note 9, 10). Furthermore, the sample\npreparation is highly robust, with controlled solution diffusion and drying steps\nensuring uniform wrinkle formation, which is critical for consistent performance at\nscale (Supplementary Figs. 58 and 59). Most critically, its unique biodegradable shell-\nrecyclable core design promotes a circular lifecycle: the pectin shell can be composted,\nwhile the valuable GO core can be recovered and reused. This synergy of economic\nviability, manufacturing scalability, and end-of-life sustainability underscores the\nprofound translational potential of the HPGP system as a transformative, eco-friendly\ntechnology for atmospheric water harvesting.”\nIn the Supporting information section:\n“Note 9: To address reproducibility and scalability of the fabrication, we\nemphasize that each unit operation relies on controllable, industry-standard aqueous\nprocesses. The wrinkled GO interlayers are formed by iterative casting and drying of a\ndefined GO dispersion, where the wrinkle wavelength and amplitude are governed\nprimarily by modulus/strain mismatch and dry film thickness set by the dispersion\nconcentration, the deposited volume, and the number of drying cycles. In our protocol,\nGO interlayers were prepared by spreading a fixed volume of GO dispersion and drying\nat 75 °C for 75 min per cycle; repeating this step four times produced the maximal\nwrinkle density while preserving layer integrity (Figs. 58-60). The subsequent pectin\ncoating and Zn2+ crosslinking (0.1 M, 10 min) maintain the surface wrinkles (Fig. 2e-\niii and Supplementary Fig. 4) and yield continuous composition across the section, as\nverified by SEM/EDS mapping (Figs.5-6). Glycerol exchange (36 h) induces a\nreproducible contraction of the pectin layer (diameter from 50 to 40 mm; Fig. 2c),\nevidencing robust interfacial coupling without disrupting the GO wrinkle morphology.\nTo support batch-to-batch consistency, we specify the process window used here (GO\nconcentration, casting volume and cycle number; pectin concentration, coating and\ncrosslinking times; glycerol exchange duration) and adopt standardized\ncharacterization: cross-sectional SEM to count layers and measure total thickness (~100\nμm, Fig. 2e), surface SEM/optical imaging analyzed by 2D fast Fourier transform to\nextract wrinkle wavelength and amplitude, and EDS line/area scans to confirm\ninterfacial continuity. These metrics provide a direct, quantitative basis for assessing\nlayer uniformity and wrinkle reproducibility across samples prepared under the same\nrecipe. Regarding scale-up, the laboratory sequence translates to continuous coating\nand treatment without changing the underlying chemistry: (i) spray, slot-die, or blade\ncoating of GO onto moving webs with multi-zone convection drying to reproduce the\niterative casting/drying history and achieve the targeted wrinkle statistics; (ii) in-line\nionotropic crosslinking in a short Zn(OAc) bath followed by water rinse; and (iii)\n2\ncounter-current glycerol exchange in a staged bath to minimize solvent use while\nmaintaining the 36 h laboratory residence time on an equivalent basis via line speed\nand bath design. Thickness increment per pass and surface morphology can be\nmonitored by areal mass control, complemented by optical texture analysis to track\nwrinkle wavelength/amplitude. Because all steps operate in aqueous media at mild\ntemperatures and use commodity materials, and because the wrinkled morphology and\ncompositional continuity are preserved through coating, crosslinking, and solvent\nexchange in our current workflow, we consider the process reproducible and compatible\nwith roll-to-roll manufacturing, enabling large-area production with controlled layer\nuniformity and wrinkle morphology.”\nComment 7:\nThe outdoor test was conducted only under moderate RH (72–82.6%) and temperature\n(23–31°C). Performance under extreme conditions (e.g., arid or highly humid climates)\nis not demonstrated, limiting the generalizability of the conclusions.\nResponse to Comment 7:\nWe thank the reviewer for raising this important point regarding the operational scope\nof the HPGP system. The initial outdoor test was indeed conducted under a specific set\nof moderate conditions, and we agree that demonstrating its performance across a wider\nclimatic range is essential to validate its generalizability. To achieve this, we conducted\ntwo multi-day outdoor experiments. However, due to current environmental constraints,\nwe performed the experiments in cooler, high-humidity conditions as well as in warmer,\ndrier conditions.\nThe first experiment was conducted in a cooler, high-humidity climate. Over three\ndays, the ambient temperature reached a maximum of 16 °C and a minimum of 7.6 °C.\nThe average temperature fluctuated between 8.8 °C and 13.1 °C. The relative humidity\nvaried significantly, with a minimum of 62.6% and a peak of 92%, while the average\nhumidity ranged from 68.1% to 84.7% (Supplementary Fig. 42). Despite the lower\ntemperatures, the higher humidity prompted the system to exhibit excellent\nperformance. Supplementary Fig. 43 shows the cumulative water collection, which\namounted to 4.79 g, 7.88 g, and 8.34 g, respectively, with daily water productions of\n4.79 g, 3.09 g, and 0.46 g. The water sorption on the first day corresponds to 2.63\nL kg -1day-1, confirming the high efficiency of the system in temperate or coastal\nwater sorbent\nregions.\nTo further validate the multi-environment adaptability of the HPGP system, a\nsecond experiment was conducted in a warmer, semi-arid environment (Supplementary\nFig. 44). The test environment featured higher average temperatures ranging from\n18.9 °C to 20.7 °C, with a maximum ambient temperature of 22.5 °C and a minimum\nof 17.7 °C. The relative humidity remained consistently low, averaging between 59%\nand 65.2%, with a minimum of 59% and a peak of 65.2%. These conditions are more\nrepresentative of regions where atmospheric water harvesting is most needed. Even\nunder lower water vapor pressure, the HPGP system operated effectively.\nSupplementary Fig. 45, the device produced 3.79 g, 1.35 g, and 0.53 g on three\nconsecutive days, respectively, with cumulative water yields of 3.57 g, 4.92 g, and 5.45\ng. The productivity on the first day was 1.96 L kg -1day-1. These two\nwater sorbent\ncomprehensive outdoor tests empirically validated the robustness and adaptability of\nour HPGP system across a broader range of real-world temperature and humidity\ndistributions, confirming its feasibility in diverse and challenging geographical\nlocations.\nThe changes are highlighted in blue in the revised manuscript and Supporting\ninformation.\nIn the Demonstration of the outdoor water-harvesting tests section (Page 21, 22, Line\n22-23, 1-4):\n“To affirm its generalizability, the HPGP system was further tested in contrasting\nclimates, demonstrating excellent adaptability. It achieved a notable water productivity\nof 2.63 L kg -1day-1 in a low-temperature, high-humidity environment (7.6–\nwater sorbent\n16°C, RH up to 92%) and 1.96 L kg -1day-1 under higher-temperature, semi-arid\nwater sorbent\nconditions (17.7–22.5°C, RH ~60%), confirming its viability for diverse geographical\ndeployment (Supplementary Figs. 42-45 and Supplementary Note 6).”\nIn the Supporting information section:\n“Note 6: To rigorously evaluate the generalizability and real-world applicability\nof our HPGP system, we conducted two additional multi-day outdoor experiments\nunder distinctly different climatic conditions, supplementing our initial proof-of-\nconcept demonstration.\nThe first experiment was performed in a cooler, high-humidity climate, \ncharacteristic of temperate or coastal environments (Fig.42). Over a three-day period,\nthe ambient temperature fluctuated between 7.6 °C and 16 °C (daily averages: 8.8–\n13.1 °C), while the relative humidity varied widely from 62.6% to a peak of 92% (daily\naverages: 68.1–84.7%). Despite the cool temperatures, the system effectively captured\nmoisture during the high-humidity nocturnal periods. The daily collected water\nvolumes were 4.79 g, 3.09 g, and 0.46 g, respectively, resulting in a total cumulative\nyield of 8.34 g over three days. The water sorption on the first day corresponds to 2.63\nL kg -1day-1, confirming the high efficiency of the system in temperate or coastal\nwater sorbent\nregions.\nTo further validate the system’s adaptability, a second experiment was conducted\nin a warmer, semi-arid climate (Fig.44), which presents a more challenging scenario for\natmospheric water harvesting. This test featured higher ambient temperatures, ranging\nfrom 17.7 °C to 22.5 °C (daily averages: 18.9–20.7 °C), and consistently lower relative\nhumidity, which remained between 57.2% and 68.7% (daily averages: 59–65.2%). Even\nunder these less favorable conditions with lower water vapor pressure, the HPGP\nsystem demonstrated reliable performance. The daily water yields were 3.57 g, 1.35 g,\nand 0.53 g, leading to a total collected volume of 5.45 g over three days. The\nproductivity on the first day was 1.96 L kg -1day-1. Together, these\nwater sorbent\ncomprehensive outdoor tests, empirically validate the adaptability of our HPGP system\nacross a broad spectrum of real-world temperature and humidity profiles, affirming its\nsignificant potential for deployment in diverse geographical locations.”\nSupplementary Fig. 42 Temperature and humidity data from three days of outdoor experiments,\nalong with the final average temperature and humidity changes.\nSupplementary Fig. 43 Total mass change of water over three days during the outdoor water-\nharvesting tests.\nSupplementary Fig. 44 Temperature and humidity data from three days of outdoor experiments,\nalong with the final average temperature and humidity changes.\nSupplementary Fig. 45 Total mass change of water over three days during the outdoor water-\nharvesting tests.\nComment 8:\nWhile ICP-MS was used to test for metal ions, no analysis was performed on potential\norganic leachates (e.g., from GO or crosslinkers). Toxicity and biocompatibility\nassessments are critical for practical applications of harvested water.\nResponse to Comment 8:\nWe sincerely agree with the insightful comments regarding water quality and recognize\nthat quantitative analysis is crucial for a comprehensive assessment of system safety\nand practical viability.\nTo address this, we conducted supplementary tests and analyses on the collected\nwater. The analysis includes ICP-MS to measure the concentration of key metal ions,\nand Total Organic Carbon (TOC) analysis, which can represent the total amount of\norganic matter. The ICP-MS test indicated that the concentrations of various key metal\nions, particularly zinc (Zn2+) used for cross-linking, were far below the safe drinking\nwater standards set by the World Health Organization (WHO). Finally, the TOC level\nin the collected water was found to be exceptionally low (<5 mg/L), which is\ncomparable to that of deionized water and further confirms the absence of leached\norganic matter (Fig. 6e).\nThe glycerol is securely immobilized within the HPGP material through both\nhydrogen bonding and chemical crosslinking. This robust immobilization prevents it\nfrom being carried over with water vapor during desorption, even across multiple\nsorption-desorption cycles. Similarly, the chemically crosslinked zinc ions remain\nstably fixed at the network nodes and do not leach into the collected water. To enhance\nthe rigor and completeness of the manuscript, we will explicitly analyze the data\nobtained from GC-MS, ICP-MS, and TOC data in the main text, thereby providing\nauthoritative quantitative support for the environmental safety of the materials and the\npurity of the produced water.\nFig. 6e Quality of collected water compared to the WHO standard.\nThe changes are highlighted in blue in the revised manuscript.\nIn the Demonstration of the outdoor water-harvesting tests section (Page 22, Line 9-\n20):\n“The stability of internal glycerol and the purity of the desorption process were\nrigorously investigated. Analysis of the vapor phase via Fourier-transform infrared\nspectroscopy (FTIR) confirmed the absence of evaporated glycerol; specifically, while\nstrong absorption peaks corresponding to the O-H bonds of water were observed (3300–\n3800 cm-1), the characteristic C-H absorption peaks of glycerol (2500–3000 cm-1) were\nundetectable (Supplementary Fig. 47). 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ACS Energy\nLett. 8, 3147–3153 (2023)."}, {"round": 2, "reviewer_comments": {"reviewer_1": "The revised manuscript and supporting information incorporate several important improvements, particularly in structural characterization (XRD, Raman, TEM), analytical techniques (ICP-MS, TOC, GC-MS), and methodological detail in the MD simulations. These changes strengthen the experimental foundation of the work.\n\nHowever, a number of key issues identified in the previous review remain insufficiently addressed. In particular, (1) validation of the proposed asymmetric-diffusion mechanism, (2) benchmarking against published sorbent systems under standardized conditions, (3) quantification of water purity, and (4) long-term environmental stability are still incomplete. These points are essential for fully supporting the manuscript’s conclusions and for aligning with the methodological standards expected in Nature Communications.\n\nA further revision is therefore required before the manuscript can be considered suitable for publication.\n\nMajor Comments\n1. Mechanism validation remains incomplete\nAlthough the revised version includes XRD and Raman data, the mechanistic claim that asymmetric hydrophilicity drives preferential diffusion is still not fully supported experimentally.\nSpecifically:\nXRD is presented under a single hydration state;\nno SAXS or XRD measurements at low vs high RH (e.g., 30% vs 90% RH) are provided;\nMD simulations remain unvalidated by any experimental technique capable of distinguishing bound vs free water.\nRequired revision:\nPlease include humidity-dependent structural data (XRD/SAXS) or, alternatively, provide an experimental proxy such as DSC, NMR, or dielectric spectroscopy to validate the MD-predicted hydration gradient.\n\n2. Benchmarking against state-of-the-art remains insufficient\nThe performance comparison to literature values remains qualitative. While the Supporting Information includes additional\ndata, the comparison is still not standardized for RH, temperature, irradiance, and sample mass.\nRequired revision:\nProvide a standardized benchmarking table under equivalent conditions (RH, temperature, cycle time, mass loading). This\nshould be placed in the main text. Please also moderate any claims of “high yield” or “fast diffusion” unless they are directly\ndemonstrated under comparable metrics.\n\n3. Statistical reproducibility is inconsistently reported\nThe Supporting Information clarifies that n = 5 sets were used for several measurements, but the main text figures still lack:\nerror bars,\nstandard deviations or confidence intervals,\nexplicit n values, and\nstatistical treatment of variability.\nRequired revision:\nAll quantitative plots should include error bars and clearly specify sample size (n) in each figure caption. This is essential for\nassessing reproducibility.\n\n4. Long-term durability and environmental stability insufficiently addressed\nThe current stability data are limited to ~45 days and fungus tests. Critical environmental stressors—UV exposure, dust,\ntemperature cycling, humidity cycling—are not addressed.\nRequired revision:\nEither expand the durability tests (UV, cycles, outdoor exposure) or provide a detailed discussion acknowledging these\nlimitations and their expected impact on real-world operation.\n\n5. Water purity analysis requires full quantification\nThe addition of ICP-MS, TOC and GC-MS is a strong improvement, but the data remain largely qualitative.\nRequired revision:\nPlease report:\nabsolute concentrations (ppm or ppb) for each detected ion/compound,\nlimits of detection (LOD) for each analytical method,\nexplicit quantification of Zn or other potential leachates.\nThis is necessary to support any claims regarding water safety or purity.\n\n6. Cost and scalability discussion is missing\nGiven the practical orientation of atmospheric water harvesting, a minimal discussion of materials cost, scalability and\nrecyclability is essential.\nRequired revision:\nPlease add a brief subsection addressing feasibility, scaling challenges, and material sustainability.\n\nMinor Comments\nImprove resolution and font sizes in schematic and microscopic figures; several panels remain hard to read.\nEnsure consistency in terminology (GO interlayers, pectin-GO gradient, GOGEL structures).\nProvide more descriptive captions in the Supporting Information, especially where multiple curves or conditions are shown.\nModerate speculative statements about large-scale implementation unless supported by data.\n\nSummary\nThe manuscript has improved substantially, particularly in analytical rigor and methodological clarity. However, several\ncritical points—mechanistic validation, benchmarking, statistical reproducibility, water purity quantification, and\nenvironmental stability—remain unresolved. Addressing these issues will significantly strengthen the manuscript and align it\nwith Nature Communications standards.\nI would be pleased to review a thoroughly revised version.", "reviewer_2": "The authors have carefully responded to our comments. Acceptance is suggested.", "reviewer_3": "Dear Authors,\nThank you for your thorough revisions and detailed responses. These changes have significantly improved the quality of the\nmanuscript. The revised manuscript (NCOMMS-25-72438A) can be accepted now."}, "author_response": ""}, {"round": 3, "reviewer_comments": {"reviewer_1": "Dear Authors,\nI would like to thank you for the substantial effort invested in this revision. The manuscript has improved significantly in clarity, experimental rigor, and overall presentation, and it is clear that the comments from the previous round were carefully and constructively addressed. The additional data and methodological clarifications have considerably strengthened the work.\n\nI appreciate the thoroughness of your responses and the care taken to improve the manuscript, and I am pleased to support its acceptance in its current form."}, "author_response": ""}]

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