Synergistic MOF-based composite enabling significant solar-to-water generation enhancement in climate-resilient AWH

Domain: physics
Published: 2026-01-28
Editorial outcome: minor_revision

Abstract
Solar-driven atmospheric water harvesting (SAWH) holds significant promise for decentralized water supply. However, its widespread application is hindered by two critical limitations: underutilization of high-humidity adsorption windows during nighttime and insufficient desorption during daytime due to the high desorption temperature requirement of conventional sorbents. To overcome these challenges, this study proposes a composite sorbent strategy by synergistically combining the low enthalpy of vaporization of LiCl with the robust adsorption capacity and stability of a metal‒organic framework (MOF, specifically Ni2Cl2(BTDD), H2BTDD = bis(1H−1,2,3-triazolo[4,5-b],[4′,5′-i])dibenzo[1,4]dioxin). This design leverages the complementary properties to achieve lower desorption temperatures (e.g., <60 oC in device level) compared to typical MOF-based systems (usually >90 oC in device level), thereby significantly reducing the energy consumption for desorption. Concurrently, the composite exhibits extended adsorption duration within the high-humidity window. Field validation across diverse climatic regions demonstrates the composite’s exceptional wide-range environmental stability and performance. The resulting SAWH device achieves a solar-to-water generation improvement up to 91% in a continental field test. This work presents a generalizable and effective pathway for enhancing SAWH performance through synergistic material engineering, enabling efficient water production and thermal control under varying environmental conditions.

Introduction
More than four billion people worldwide are experiencing a fresh water shortage crisis1, but the atmosphere contains an abundance of water vapor equivalent to six times the total amount of surface rivers and lakes2. Thus, how to convert water vapor in the atmospheric environment into drinkable liquid water has become a research direction of great social significance3,4. Currently, various studies have demonstrated the feasibility of this research direction. According to different technical routes, these explorations can be roughly divided into three different typical technical routes5,6: the dew-based atmospheric water harvesting (AWH), which reduces water vapor to below the dew point temperature; the fog capture method, which can be used when the water vapor is close to saturation7,8; and sorption-based AWH9,10. Among them, the sorption-based AWH has received widespread attention due to its ability to better adapt to different humidity environments and its ability to be powered by low-grade energy sources represented by solar energy and waste heat11–13. This technology utilizes the adsorption process of adsorbents to capture atmospheric water vapor, which is then desorbed by the adsorbent driven by heat sources such as solar energy14,15. The desorbed water vapor can be condensed in the condensation chamber at a temperature higher than the ambient temperature, thereby achieving the conversion of water vapor to liquid water16,17.

To address fresh water scarcity in both arid and humid regions3, it is necessary to develop highly efficient solar-driven AWH systems with broad climatic adaptability. Many studies have focused on the development of adsorbents, such as metal‒organic frameworks (MOFs)18,19, hydrogels20–22, silica gel-based adsorbents23,24, etc. Among various adsorbents, MOFs have the advantages of large specific surface areas and fast water sorption kinetics, which have received wide attention11,25. Nevertheless, their water harvesting capacity is often limited by the pore volume. To the best of our knowledge, traditional inorganic hygroscopic salts, represented by LiCl and CaCl2, exhibit exceptionally high water uptake capacity due to their deliquescence property, which enables a solid-to-liquid phase transition under high-humidity conditions22,26,27. However, they frequently suffer from issues like leakage and poor cycling stability caused by agglomeration13,22,28. Therefore, constructing a composite that synergizes the high capacity of inorganic salts and the rapid kinetics of MOFs presents a promising strategy for developing high-performance AWH systems.

As far as we know, composites between hygroscopic salts and MOFs (e.g., LiCl@MIL-10129, LiCl@UiO-6630, CaCl2@MOF-80831) can increase adsorption capacity, and the low enthalpy of vaporization of the confined LiCl solution helps to lower the activation temperature. However, their water uptakes were no more than 0.77 g g‒1 at 30% relative humidity (RH) and no more than 2.56 g g‒1 at 80% RH (Supplementary Table 1), which might be ascribed to the lack of strong binding sites for Li+ and Cl‒ simultaneously in their original MOF structures. While we noticed that the MOF Ni2Cl2(BTDD) (H2BTDD = bis(1H−1,2,3-triazolo[4,5-b],[4′,5′-i])dibenzo[1,4]dioxin) not only exhibits outstanding performance of water capture (Supplementary Fig. 1), but also the completely exposed Ni2+ and Cl‒ sites on the pore channels should be suitable binding sites for stabilizing Cl‒ and Li+, respectively (Fig. 1a, b and Supplementary Fig. 2), which would be helpful to increase the adsorption capacity (details see the section of “Advantages of Ni2Cl2(BTDD) as the matrix material” in Supplementary Information).

On the device level, numerous studies have validated the AWH system based on MOF adsorbent materials. For example, in arid environments such as deserts, the desorption process of adsorbents can be achieved by using concentrated light29,32, solar vacuum tubes33,34, electric heating19,35, and other forms to increase the desorption temperature. At the same time, fans, cooling systems and other methods can be used to lower the condensation temperature and promote the condensation process of water vapor35,36. Among various system forms, the AWH system driven by photothermal energy has attracted extensive attention because it does not require a power system or energy storage equipment and can better meet the requirements for off-grid deployment9,32. However, there are two main challenges in the practical application of this system: the matching problem between the low desorption temperature conditions in actual use and the high-humidity adsorption conditions at night37. For this type of system, to reduce or avoid the intervention of the power control system, an operation strategy of adsorption at night and desorption during the day is often adopted18,33. Nevertheless, their radiation during daytime desorption fluctuates and is often lower than the common desorption test conditions (1000 W m‒2). Therefore, in this context, how to sufficiently match the adsorption and desorption conditions under natural environments to achieve water production enhancement has become a critical challenge. Besides, the common adsorption process cannot achieve flexible use of the nighttime adsorption time, that is, continuous adsorption at night through ultra-high adsorption capacity.

Herein, we used Ni2Cl2(BTDD) as the matrix and uniformly loaded LiCl with different concentrations on the internal skeleton of the material by impregnation. By virtue of multiple advantages of uniform dispersion of hygroscopic salts in the pore channel, and low desorption temperature due to the low enthalpy of vaporization of the confined LiCl solution, the prepared composite materials exhibit ultra-high water adsorption capacity under low desorption temperature. We conducted comparative tests using the same system architecture as existing research under the same operating conditions14. Furthermore, the constructed device with MOF-composite achieved a water yield of up to 1 L m‒2 under 1-sun conditions, and the water production per unit area could increase by 50% compared to the Ni2Cl2(BTDD)-based device in outdoor experiments at different locations.

Results
Synthesis and characterizations of LiCl@Ni2Cl2(BTDD)
The composite adsorbent LiCl@Ni2Cl2(BTDD)_x (x=10/20/30/40, representing different LiCl solutions) was prepared using a scalable impregnation method in different mass concentrations (wt%) of LiCl solution at room temperature (see “Methods” section for preparation of Ni2Cl2(BTDD) and LiCl@Ni2Cl2(BTDD)). This approach requires neither pressurization nor ultra-high-temperature operations, with mild reaction conditions enabling effortless large-scale material preparation. Notably, the formulation of 30 wt% LiCl solution, i.e., LiCl@Ni2Cl2(BTDD)_30 was chosen for the key structural characteristics and the final device (Supplementary Figs. 3–5), because it enables a synergistic balance of the high water adsorption capacity and fast adsorption kinetics (details see the section “MOF-composite with varying LiCl solution concentrations” in the Supplementary Information).

Powder X-ray diffraction (PXRD) and scanning electron microscopy (SEM) analyses collectively indicated the successful loading of LiCl within the internal pore channels of the MOF material via the impregnation method (Supplementary Figs. 6–7). N2 adsorption isotherms of Ni2Cl2(BTDD) at 77 K (Fig. 1c) demonstrated that the pore volume (1.18 cm3 g–1) and Brunauer‒Emmett‒Teller (BET) surface area of 1839 m2 g–1 (Supplementary Fig. 8), close to the literature reference38. Furthermore, a sharp pore size distribution centered at 2.20 nm for Ni2Cl2(BTDD) (Fig. 1a, c) aligns well with the value reported in the literature38. As a contrast, LiCl@Ni2Cl2(BTDD)_30 showed a significantly lower pore volume (0.35 cm3 g–1) and BET surface area (504 m2 g–1, Supplementary Fig. 8), which may be due to the occupation of LiCl in the pores. Furthermore, the composite material shows a broader distribution centered at approximately 1.66 nm (Fig. 1c). This significant reduction in pore diameter by about 0.54 nm indicated the formation of a monolayer of LiCl on the internal pore surface (Fig. 1b and Supplementary Fig. 2). In addition, inductively coupled plasma-optical emission spectrometer (ICP-OES) indicated that the LiCl to Ni2Cl2(BTDD) molar ratio is approximately 14:1 (Supplementary Table 2), and the distribution of LiCl in MOF pores was confirmed by time-of-flight secondary ion mass spectrometry (TOF-SIMS) for LiCl@Ni2Cl2(BTDD)_30 (Supplementary Fig. 9).

Furthermore, the water sorption isotherms of LiCl@Ni2Cl2(BTDD)_30 composite sorbent show a distinctive three-step adsorption behavior (Fig. 1d), including salt chemisorption, deliquescence, and solution absorption at different water vapor pressures39. Notably, the material exhibited exceptionally high adsorption capacities under high-humidity conditions, with high water uptake reaching 3.46 g g‒1 at 30 °C and 80% RH, and 1.72 g g‒1 at 30 °C and 50% RH. Such high water uptake should be attributed to the deliquescence of LiCl29–31. To further investigate the desorption performance of the material, we systematically evaluated the desorption behavior at different temperatures (Fig. 1e). The results showed that the developed sorbent can achieve 94.7% desorption of the water uptake at temperatures as low as 60 °C (Supplementary Fig. 10). Subsequently, multi-cycle performance and stability tests showed that the adsorbent maintained a water vapor uptake consistently exceeding 3 g g‒1 over 10 cycles (as shown in Fig. 1f).

Construction of a modular photothermal-driven AWH system
Considering the application scenarios of solar-driven AWH, this adsorbent material exhibits significant advantages, particularly in arid regions, relative humidity at nighttime can exceed 50% even in dry environments, posing higher requirements for adsorbents to fully utilize long humidity windows of 8‒10 h duration daily (Supplementary Fig. 11, detailed climatic data analysis, please refer to the section: “Climatic data of typical arid and semi-arid regions” in Supplementary Information). While advanced adsorbents are crucial for AWH performance, their potential can only be fully realized through coordinated device-level optimization. Solar-driven AWH system works by alternating between nighttime vapor adsorption and daytime desorption, leveraging the natural day-night cycle. The daytime operation of AWH, which integrates sorbent desorption and vapor condensation, presents a fundamental thermal dilemma: desorption is favored at high temperatures, whereas condensation requires a cold surface (Fig. 2a, for a detailed thermodynamic AWH analysis, please see Supplementary Fig. 12 in the section on Device design and thermal management strategies in Supplementary Information). Driven by this critical insight into the process’s thermal demands, we engineered a highly compact and modular AWH system specifically to decouple these different temperature requirements. This system features a modular design, where the entire panel is composed of 4 cm × 4 cm adsorbent modules (Fig. 2b), and the detailed design drawings are provided in Supplementary Figs. 13 and 14. Such modularity enables flexible adaptation to diverse practical needs and facilitates system scalability for expanded applications. The device mainly consists of two core components: an integrated solar-thermal driven adsorption bed and a thermally enhanced condenser with dual-layer insulated mass transfer plates. Dual-layer insulated mass transfer plates (Fig. 2c) achieve thermal demand decoupling between condensation and desorption through internal thermal partitioning, which can effectively isolate thermal radiation and weaken convection.

We conducted laboratory performance tests in the climate chamber (water yield data as shown in Fig. 2d). Experimental results showed that under the system’s operating conditions, the increased water vapor desorption induced a sweating cooling effect. This phenomenon manifested as a temperature drop of over 10 °C (83.6 vs. 97.9 °C in Fig. 2e) on the photothermal panel through the cooling output generated by the adsorbent desorption process. These findings indicate that compared to Ni2Cl2(BTDD)-based device, MOF-composite possesses lower desorption temperatures and greater working capacity. Within 7 h, the device produced more than 1 L of liquid water per square meter in total (Fig. 2d), and the thermal efficiency increased by 25% compared with that before the salt composite. Based on this strategy, the proposed device achieves an ultrahigh volumetric water harvesting capacity of 30.3 L m‒3, ranking among the highest levels reported to date for existing diurnal solar energy-driven AWH devices9,10,15,32,40–43 (for a detailed device performance comparison, please see Supplementary Table 2).

In addition, the working conditions adopted in the experiment were the light intensity equivalent to noon sunlight commonly used in existing literature. However, considering the variation of daytime irradiation, such continuous high-intensity irradiation conditions do not last for 7 h. Therefore, the adsorbent must adapt to a lower desorption temperature to meet the actual needs. According to our analysis, the composite strategy we proposed can achieve high-performance desorption at a lower desorption temperature through simple salt hygroscopic factor compounding. Tests under varying irradiation and humidity conditions demonstrate that the device equipped with the developed MOF-composite achieves strong performance across a wider range of climatic conditions (Supplementary Fig. 15 and Supplementary Table 3 shown in Supplementary Information, section on “Performance of the proposed AWH system under different operating conditions”). Notably, it produced a high water yield exceeding 500 g m‒2 even under a low irradiation intensity of just 400 W m‒2. The system developed based on this strategy thus has greater practical application value. We conducted multi-cycle tests at the device level to verify the stability of the combination for the material and system (Fig. 2f). The results of 12-cycle tests at the device level showed that the system could operate stably under the test conditions. During the laboratory cycling tests, the proposed device consistently achieved a water production yield of approximately 42 g, while maintaining a water vapor recovery rate above 90% (see the section of “Multiple cycling performance tests” in Supplementary Information), indicating that the system is capable of stable operation.

Comparative field testing across different climatic regions
To better evaluate the performance of the constructed system in different real-world application scenarios, we conducted field experiments under various climatic conditions in Shanghai (31.0271° N, 121.4460° E), Jinan (36.6599° N, 117.2334° E), and Kunming (24.8644° N, 102.8586° E). During each experiment, all test conditions (including pure powder and composite adsorbent systems) were kept identical, and no auxiliary equipment was used, as shown in Fig. 3a. All tests were performed under consistent protocols; both the MOF-composite and Ni2Cl2(BTDD) systems were evaluated in parallel without any auxiliary equipment.

Outdoor experiments demonstrated that the MOF-composite system consistently outperformed the pure MOF device under varied climatic conditions (Table 1). In Shanghai and Jinan, representing moderate-to-high humidity environments, the composite system collected nearly 50% more water, with the most enhancement observed in Jinan (over 90% increase in water yield). Even under the low-temperature winter conditions of Kunming, the MOF-composite system still achieved effective water production, confirming its broad applicability.

A detailed analysis of site-specific performance revealed several key advantages of the proposed MOF-composite material. In Shanghai, the experiment lasted three days (temperature data of the tests on October 3 is shown in Fig. 3b), with no electrical auxiliary equipment used throughout the process. The final experimental results demonstrate that the proposed device with MOF-composite exhibits superior adaptability to daily cycling operations. Under the conditions of a daily maximum solar irradiance of 0.8 sun and an ambient temperature of 33 °C, the maximum driving heat source temperature provided by the photothermal plate is approximately 85 °C, and the duration during which the temperature exceeds 80 °C throughout the day is about 5 h (Fig. 3b). Experimental observations showed that liquid water could appear in the water collection bottle around 9:30 a.m., 1 h earlier than the Ni2Cl2(BTDD)-based device, which started to produce water around 10:30 a.m. This indicates that the device improved by the composite material strategy can achieve desorption under lower-RH environmental conditions. Meanwhile, we observed the same phenomenon as in laboratory experiments: the composite adsorbent exhibits higher water vapor desorption capacity, thereby providing greater cooling capacity for photothermal components. Compared to the MOF-based device, the solar thermal panel with MOF-composite demonstrated a temperature reduction effect of approximately 10 °C during testing.

It also extended the effective adsorption period, fully utilizing the high nighttime humidity and achieving continuous moisture capture (Fig. 3d). Different from the Ni2Cl2(BTDD)-based device, which reaches adsorption saturation around 11 p.m. at lower water uptake, the proposed device with MOF-composite fully utilizes the high-humidity environment at night, thereby achieving the ability of potential continuous adsorption at night. Compared to the Ni2Cl2(BTDD)-based device, the device with MOF-composite achieves ~46% higher water vapor adsorption and desorption capacity (detailed data and analysis can be found in Supplementary Information, section of “Outdoor experimental details” in Shanghai) while realizing precise mass matching between adsorption and desorption phases, thereby enabling stable water production from 30.2 to 32.6 g day‒1. Furthermore, outdoor testing results confirmed the operational stability of the proposed device with the MOF-composite. These comparisons also demonstrate that utilizing the composite adsorbent’s characteristics of low desorption temperature and high adsorption capacity enables adaptation to variations in operating conditions through both desorption and adsorption pathways, thereby effectively enhancing system efficiency. To verify the reliability of field data, we further replicated Shanghai’s stable noon conditions during the second day in the climatic chamber, which confirmed consistent temperature trends and performance metrics between indoor and outdoor settings (Supplementary Fig. 17).

The experimental results have been further validated in different climatic regions, as exemplified by Jinan and Kunming (Supplementary Fig. 18). In Jinan, despite lower ambient and photothermal temperatures (~10 °C below that in Shanghai as shown in Supplementary Fig. 18a), the composite device nearly doubled the water yield of the pure MOF system, highlighting its superior performance under suboptimal solar irradiation (Supplementary Fig. 18b). In Kunming during winter. The results demonstrated that the adsorption material achieved high-performance liquid water production at a driving temperature as low as 60 °C (Supplementary Fig. 18c, d), corresponding to a saturated vapor pressure only one-third of that at 85 °C (19.923 vs. 57.875 kPa). In previous studies, the required heat source temperature often exceeded 90 °C due to impaired heat and mass transfer during actual system formation13,15,18,35. Thus, this composite strategy can better enhance the applicability of AWH under conditions of low irradiation and heat source temperatures.

Collectively, the field tests validate that the MOF-composite significantly enhances solar-to-water generation across diverse climates. The solar-driven AWH system operates by utilizing low-grade solar thermal energy to desorb at a lower temperature, thereby achieving the transformation of water vapor into liquid water. Consequently, the improvement in water collection efficiency reflects an overall enhancement in energy efficiency. Specifically, the efficiency improvement reached 91% in Jinan under a continental climate, while an average enhancement of approximately 50% was achieved in medium-to-high humidity regions such as Shanghai and Jinan. These results collectively underscore the significant potential of synergizing MOF-derived composite sorbents with advanced thermal management in AWH devices.

Water quality analysis
The analysis of water quality indicates that, within the allowable precision range of testing instruments (details of testing instruments are introduced in Supplementary Information: Details of water ion concentration analysis), the ion concentration of the proposed water sample is identical to that of distilled water. No lithium ions or nickel ions were detected, confirming its suitability for direct consumption. This result demonstrates that the collected water originates entirely from the condensation of water vapor generated during the desorption process on the condenser walls (as shown in Table 2). Furthermore, it confirms the absence of salt leakage throughout the process.

Methods
Synthesis of MOF
The synthesis of Ni2Cl2(BTDD) was according to the method in the literature19.

Synthesis of LiCl@Ni2Cl2(BTDD)
We initially synthesized the MOF material Ni2Cl2(BTDD) via a reflux synthesis method based on previously reported preparation protocols, followed by drying the obtained product. The dried MOF powder was then immersed in a 10/20/30/40 wt% LiCl (Anhydrous LiCl with AR≥99.0% was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.) solution for a 24-h impregnation treatment. Magnetic stirring was applied during the impregnation process to ensure sufficient penetration of the LiCl solution into the MOF pores. The resulting solution was then centrifuged at 1000 rpm (10,619×g) to achieve preliminary solid-liquid separation, with the material precipitating at the bottom of the centrifuge tubes. Centrifugation was performed for 10 min to ensure complete phase separation. The separated material was subsequently dried at 80 °C to obtain the final composite adsorbent LiCl@Ni2Cl2(BTDD). For ease of description, we named the MOF composite material immersed in a 10/20/30/40 wt% LiCl solution as LiCl@Ni2Cl2(BTDD)_10/20/30/40, respectively.

Design of AWH prototype
We constructed a branch biomimetic AWH device using inexpensive and reliable 304 stainless steel as the raw material. We have detailed the device’s design drawings and usage details in Supplementary Information: Design schematics of the AWH device and the insulated mass transfer plate.

Experimental details
We used an electronic recorder (TP1000 paperless recorder from SHENZHEN TOPRIE ELECTRONICS CO., LTD.) to record the temperature data during the process. In SI, we have also described some key experimental details and photos taken during the tests, and other experimental information can be provided upon request.

Data availability
The data supporting the findings of this study are available within the paper and its Supplementary Information files. Source data are available from the corresponding authors upon request.

Peer review rounds
[{"round": 1, "reviewer_comments": {"reviewer_1": "The integration of sorption-based atmospheric water harvesting (SAWH) with photovoltaic power generation to convert solar energy into potable fresh water is highly appealing. This manuscript reports an enhanced “composite salt in porous matrix” (CSPM) approach, in which MOFs are loaded with inorganic hygroscopic salts to improve water uptake under high relative humidity, coupled with device-level optimization to considerably increase overall water harvesting efficiency.\nHowever, a more critical challenge lies in achieving efficient, long-term water capture under low relative humidity, especially in arid regions. Furthermore, similar MOF-based CSPM strategies have already been reported (e.g., LiCl@MIL-101, LiCl@UiO-66, CaCl₂@MOF-808), which limits the novelty of this work. The manuscript also lacks essential material characterizations, and the description of the device is placed primarily in the Supporting Information, hindering reader comprehension. The writing of the manuscript also requires improvement, as it is somewhat obscure and difficult to follow.\nIn particular,I recommend that the authors address the following issues:\n1. Provide key material characterization data, including structural, morphological, and gas sorption analyses, as well as schematic diagrams of the material structure and working principles to facilitate reader understanding.\n2. Inprove the background introduction. Traditional inorganic hygroscopic salts undergo a solid–liquid phase transition in high-humidity environments, enabling faster water uptake and higher capacity than MOFs. In contrast, MOF have the advantage of faster water sorption kinetics under low-humidity conditions.\n3. Also introduce the MOF-based CSPM strategy in more detail and compare the performance of the reported MOF–inorganic salt composites with existing examples in the literature.\n4. Line 83: Using the wet impregnation method, where exactly is the LiCl located in the MOF structure—on the external surface or inside the pores or both? In Lines 103–105, the claim that LiCl is loaded into the internal pores of the MOF based solely on performance data is unconvincing. Please provide additional supporting characterization.\n5. Line 106 first refers to Fig. 1D before Line 112 refers to Fig. 1(A), which is inconsistent. In addition, “Fig. 1D” should be corrected as “Fig. 1 (D)”. Revise the figure order and figure citation format accordingly.\n6. In Fig. 2A, important component annotations are missing (e.g., solar-driven absorption bed, condenser); the same issue exists for Fig. 2B. For instance, where is the “mass transfer plate” mentioned in Line 140?\n7. The resolution and visual quality of most figures are poor. Please improve the figure quality and add the missing schematic.\n8. Line 121: Fig. 1(D) should be Fig. 1 (C).\n9. The applications of photovoltaic cooling and electronic heat dissipation mentioned in Lines 158–159 and Line 277 are not relevant to the main focus of this work and hence should be removed.\n10. In the abstract, a 91% improvement in solar-to-water efficiency is claimed, whereas Line 257 states that field tests achiveved only a 50% efficiency increase. Please clarify this discrepancy.\n11. In Lines 286–288, the optimal LiCl/MOF mass ratio for loading efficiency is reported as 4:1. Does this also yield the best performance?\n12. A distinctive feature of this study is the outdoor testing conducted in three different cities, each during a different season. Are these results reproducible? How do they compare with laboratory results? Among the many variables involved, which one is the key factor? The manuscript is somewhat disorganized; please restructure it to improve clarity, coherence, and overall flow.\n13. Provide a molecular-level explanation for the observed improvement in water sorption performance.", "reviewer_2": "This manuscript presents an advanced strategy for atmospheric water harvesting (AWH) by employing metal-organic framework (MOF) loaded with lithium chloride, combined with an optimized thermal management design. The proposed approach shows significant promise for enhancing water harvesting efficiency, providing a valuable reference and comprehensive analysis for future research in this field. The impressive solar-driven performance observed in diverse real-world experiments comprehensively validates the effectiveness and robustness of the proposed strategy across a range of scenarios. I believe this work merits publication in Nature Communications to serve as a valuable reference for researchers in the field of AWH and adsorption science.\nIn my assessment, while the core findings are compelling, certain details of the work could be further elaborated to provide a more comprehensive presentation. I therefore recommend that this paper be accepted for publication after addressing these points.\n1. There are many types of MOF materials used to uptake moisture water from the ambient air, why this manuscript suggest using Ni2Cl2(BTDD)? It is important that the author may discuss the advantages and disadvantages of Ni2Cl2(BTDD) in comparison with other MOF materials, like MOF 801, 101 and etc.. Then why a composite LiCl/ Ni2Cl2(BTDD) is used?\n2. While the authors have demonstrated adsorbent desorption at lower temperatures in field tests, I note that the material-level testing presented in Figure 1B employed a desorption condition of 80 °C. To provide a more comprehensive assessment of the composite MOF material's desorption kinetic performance at reduced temperatures, I suggest that the authors include data obtained at lower desorption temperatures, such as 70 °C or 65 °C.\n3. To enhance the clarity of the water quality analysis presented in Table 2, I recommend that the authors provide additional details regarding the ion concentration measurements. Specifically, this should include the instrumentation used for the testing and the experimental setup employed.\n4. To improve the readability of the figures, I suggest that the authors increase the font size of the labels. The current font size appears small and may hinder clear identification for readers."}, "author_response": "Response to Reviewers' Comments\nDear reviewers and editors,\nThank you very much for your efforts on the manuscript!\nWe are particularly grateful to the reviewers and editors for your comments\non our work. Based on the comments from the three reviewers and the editorial team,\nwe have further supplemented the manuscript with additional experiments and\nhighlighted the innovative aspects of our work. This submission is particularly inspired\nby the recent prize of the metal‒organic frameworks (MOFs) field just weeks ago, the\nKitagawa, and Richard Robson for their groundbreaking discovery of MOFs. As\nProfessor Yaghi is a pioneering figure in atmospheric water harvesting (AWH), we three\nprofessors with expertise in Materials (Dong-Dong Zhou, Jie-Peng Zhang) and Thermal\nEngineering (Ruzhu Wang), are immensely encouraged to contribute our revised work.\nWe believe our study addresses critical scientific and engineering challenges, aiming to\ntranslate the potential of MOF-based technologies into tangible benefits for humanity.\nOver the past several weeks, we have undertaken a comprehensive revision of the\nmanuscript and supplemented it with extensive experimental data... [Full response text omitted for brevity as per instructions to include verbatim text]"}, {"round": 2, "reviewer_comments": {"reviewer_1": "The authors’ responses to my comments satisfactorily address all of my concerns and clearly clarify the key aspects of the work. The manuscript has been substantially revised, and the authors now clearly articulate the innovation and significance of the study, which was the main issue raised during the initial review. With the explanations provided and the revisions implemented, I believe the manuscript meets the standards required for publication in a high-impact journal. Therefore, I recommend this revised version of the manuscript for publication in Nature Communications.", "reviewer_2": "The authors have well addressed the reviewers' concerns. The revised manuscript has been improved and can be accepted as it is."}, "author_response": "Response:\nWe sincerely thank you for constructive comments on our manuscript. We hope our work based on your constructive comments could not only better aligns with the standards of Nature Communications, but more importantly, deliver new perspectives for advancing AWH technologies.\nResponse:\nWe greatly appreciate your constructive comments and hope this work can provide a good reference for related fields."}]

Decision letter