Interfacial configurational entropy tuning strategy enabling liquid alloys for efficient depolymerization of polyolefin waste

Domain: biology
Published: 2026-03-12
Editorial outcome: major_revision

Abstract
Accumulation of plastic waste presents a global environmental crisis, posing severe threats to ecosystems. Depolymerization offers a promising route for closed-loop recycling of plastic waste. Nevertheless, depolymerizing chemically stable polyolefins remains challenging, yet fails to achieve high light olefin yields and stability. Herein, we propose an interfacial configurational entropy tuning strategy for liquid alloy catalysts, inducing active site interfacial enrichment and optimizing electronic structure. With this strategy, a quaternary GaInNiSn catalyst with medium entropy is developed for recycling polyolefins into light olefins under atmospheric pressure without co-reactant consumption, achieving a space-time yield of 181.5 mmol g ⁻1 h⁻1. Mechanistic insights reveal that Niδ⁻–Snδ+ active sites form within the dynamic Ga interface, enabling C–H bond activation to promote β-scission. Furthermore, a photovoltaics-driven depolymerization system is constructed, maintaining light olefin output of 52.8 L h⁻1 over 120 hours. Our work unlocks a potent tool for efficient and sustainable plastic waste utilization.

Introduction
Plastics, the most extensively used synthetic materials in modern society, have revolutionized human civilization through their exceptional durability, versatility, and modifiability1, 2. It is anticipated that the annual global plastic production will reach 1.2 billion tons by 2050, with a staggering accumulation of waste plastics of 25 billion tons3, 4. However, plastics exhibit resistance to natural degradation and currently lack cost-effective recycling solutions. Globally, less than 10% of waste plastic undergoes proper recycling, and the overwhelming majority of discarded plastic contributes to severe environmental degradation and substantial resource depletion5, 6, 7. This striking disparity between the explosive growth in plastic production and the persistently low recycling rate threatens to trigger incalculable ecological crises8. Accordingly, the implementation of systematic waste plastic recycling is critically urgent, particularly for polyolefins, which constitute over 77% of global plastic production and dominate the waste stream3, 9. At present, physical recycling is largely confined to single-category, clean, and high-value waste plastics; in stark contrast, chemical recycling circumvents these limitations by deconstructing polymers at the molecular level to regenerate high-quality products10, 11. Although chemical recycling technology is well-established for easily recoverable polyesters like polyethylene terephthalate (PET), its application to chemically stable polyolefins, such as polyethylene (PE) and polypropylene (PP), remains a formidable challenge12, 13.

Depolymerizing polyolefins into monomers, chemically identical to petroleum-derived precursors, represents the most promising approach among chemical recycling technologies14, 15. These reclaimed monomers can be directly repolymerized into new plastic products or utilized as platform chemicals in value-added industrial processes. Nonetheless, depolymerization of polyolefin waste is hindered by the inherent inertness of C–C and C–H bonds, necessitating harsh conditions to overcome kinetic and thermodynamic barriers16, 17, 18. Moreover, efficient depolymerization entails not only cleaving these inert bonds but also precise control over the cleavage process to avoid random dissociation19, 20. Existing depolymerization approaches, consequently, are typically energy-intensive and involve significant efforts to improve product yield21, 22. In this context, pulsed electrified heating offers a highly competitive process for polyolefin depolymerization23, 24. This process utilizes transient heating to overcome kinetic barriers, followed by cooling, shifting the depolymerization reaction away from chemical equilibrium and suppressing side reactions. Despite these merits, the pronounced asymmetry between heating and cooling durations, in which cooling requires nine times longer than heating, drastically reduces the space-time yield (6.57 mmol C H cm⁻2 h⁻1). Disruptively, the tandem catalytic cracking and isomerizing ethenolysis process (CIE) ingeniously integrates olefin isomerization and olefin metathesis, enhancing monomer selectivity to attain a high C H space-time yield of 135.5 mmol g ⁻1 h⁻1 in polyolefin depolymerization, representing the highest level attained to date25, 26. Nevertheless, this process requires elevated pressures and near-stoichiometric C H co-reactant consumption. The operational stability of these depolymerization processes, additionally, requires further enhancement, with current continuous operation durations less than five hours23, 26. Therefore, it is imperative to develop depolymerization processes integrating high space-time yield, outstanding monomer selectivity, robust operational stability, and cost-effectiveness.

Herein, we report a catalytic depolymerization process using induction-heated liquid alloys (Fig. 1), converting polyolefin waste into light olefins at atmospheric pressure without requiring co-reactants. Central to this process is a quaternary GaInNiSn liquid alloy catalyst (LAC, Supplementary Table 1), which is designed by an interfacial configurational entropy (S ) tuning strategy (Supplementary Note 1). We incorporate three elements into the dominant Ga liquid metal to induce atomic disorder at the alloy interface, thus forming a medium-entropy liquid alloy GaInNiSn (MELAC) with a S of 1.16R. In stark contrast to the binary or ternary liquid alloy catalysts, the increase in the S of MELAC attenuates interfacial Gibbs free energy (Eq. S9), thereby modulating Ni active sites and promoting their enrichment on the Ga interface. Leveraging induction heating for rapid depolymerization, the process significantly suppresses low-temperature side reactions and facilitates PP depolymerization, delivering a space-time yield (STY) of 181.5 mmol g ⁻1 h⁻1 with a selectivity of 79.7%. Mechanistic insights suggest that Sn electronically modifies Ni to form Niδ⁻–Snδ+ sites at the GaIn interface, activating C–H bonds for selective depolymerization via β-scission. Furthermore, we constructed an outdoor photovoltaics-driven depolymerization system for real-world polyolefin waste, maintaining a light olefin production rate of 52.8 L h⁻1 in more than 120 hours of continuous operation. This system holds promise for the large-scale depolymerization of waste polyolefin plastics into light olefins, contributing to sustainable resource utilization and net-zero carbon emissions.

Results
Synthesis and characterization of GaInNiSn MELAC

The quaternary GaInNiSn LAC was synthesized by the ‘one-pot’ method (Supplementary Fig. 1). High-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) analysis showed that the GaInNiSn MELAC maintained a homogeneous liquid phase state at room temperature, with no discernible presence of metal or metal oxide nanoparticles (Supplementary Fig. 2a,b). Energy dispersive X-ray spectroscopy (EDS) mapping (Fig. 2a) disclosed a uniform distribution of the active metal Ni and the regulatory metal Sn within the Ga solvent matrix. Inductively coupled plasma-optical emission spectrometry confirmed a Ni-to-Sn molar ratio of 3:1, corresponding to weight percentages of approximately 6.01 wt% Ni and 4.07 wt% Sn (Supplementary Table 2). The Hall effect measurement revealed that the GaInNi LELAC and GaInNiSn MELAC exhibit excellent electrical conductivity (Supplementary Table 3), serving as the receptor of induction heating. Contact angle tests (Supplementary Fig. 3) exhibited that Sn incorporation remarkably reduced the surface tension of GaIn alloys, thus providing a large solid-liquid contact area for plastic depolymerization. In-situ X-ray photoelectron spectroscopy (XPS) analysis corroborated the presence of Ni, Sn, Ga, and In in the GaInNiSn (Supplementary Figs. 4–6), while the GaInNi LAC did not exhibit distinct peaks of Ni 2p signals (Fig. 2b), suggesting that the incorporation of Sn atoms promotes the enrichment of Ni atoms at the alloy surface. Notably, the GaInNiSn LAC exhibited a S of 9.62 J·mol−1 K−1 (1.16R) and resided within a medium-entropy range spanning 1.0R to 1.5R. In stark contrast to the binary or ternary LAC, the S of quaternary GaInNiSn was remarkably greater than those of low-entropy liquid alloys (LELAC) (Fig. 2c). This attribute endows the GaInNiSn MELAC with low interfacial Gibbs free energy (Supplementary Note 1), thus facilitating interfacial enrichment and reconstruction of active sites30. Ab initio molecular dynamics calculations (Supplementary Fig. 7) further disclosed that the Sn atom dragged the Ni atom outward to the surface of GaIn LELAC on account of the strong Sn–Ni interaction, attenuating the surface tension of the GaInNi LELAC. This phenomenon manifests that the introduction of Sn increases the S at the interface by inducing atomic disorder, thus disrupting the original coordination environment and forming Sn–Ni interactions31, 32. Moreover, the robust Sn–Ni interaction reduces the energy barrier for Ni migration to the surface and overcomes the solvation constraints imposed by the surrounding Ga atoms33, 34. Since the depolymerization process by LAC is a typical solid-liquid heterogeneous catalysis reaction, the Ni surface enrichment in the GaInNiSn MELAC contributes to enlarging the active specific surface area, leading to superior performance in the bond cleavage process. Furthermore, the GaInNiSn MELAC induces a distinct shift of the Ni 2p peak to low binding energy, accompanied by a concurrent shift of the Sn 3d peak to high binding energy (Supplementary Figs. 4,5), indicating potential electron donation characterized by Niδ⁻–Snδ+ polarization. Notably, despite the elevated temperature of 500 oC augments Ga solvent mobility, the increase in the S inhibits the agglomeration of active Ni sites and their diffusion into the Ga bulk phase (Supplementary Table 1). Meanwhile, the strong Sn−Ni electronic interaction dynamically anchors the Niδ⁻ atoms at the interface, preventing their encapsulation by surrounding Ga or In atoms.

X-ray absorption spectroscopy (XAS), furthermore, uncovered the electron state and precise local coordination of Ni atoms in the GaInNiSn MELAC. The X-ray absorption near-edge structure (XANES) spectrum of Ni K-edge (Fig. 2d) exhibited a pronounced negative absorption edge shift for the GaInNiSn MELAC relative to Ni foil, contrasting with the negligible change in the GaInNi LELAC. This shift confirms substantial electron accumulation at Ni atoms in the Sn-incorporated system, whereas the Sn-free system retains Ni atoms in a near-zero valence state. The Sn K-edge XANES spectrum (Fig. 2e) showed an absorption edge in the GaInNiSn MELAC positioned between Sn foil and SnO , suggesting a partial positive charge (Snδ+, 0 < δ < 4) with reduced electron density. The electronic states of Niδ⁻ and Snδ+ corroborate the charge transfer from Sn to Ni, forming the Niδ⁻–Snδ+ sites in the GaInNiSn MELAC, as identified by in-situ XPS and charge density difference (Supplementary Fig. 8). To obtain an accurate coordination configuration for the GaInNiSn MELAC, Fourier transform (FT) k2-weighted extended X-ray absorption fine structure (EXAFS) spectra were collected. The Ni K-edge FT-EXAFS spectra showed that the first peak in the GaInNiSn MELAC corresponded to the Ni−Ga path, closely matching the Ni−Ga peak in the GaInNi LELAC (Supplementary Fig. 9). Furthermore, a Ni–Ga peak for the GaInNiSn MELAC at (R + α) = 2.08 and k = 6.64 in Wavelet transform (WT) analysis resembled the Ni−Ga bond in the GaInNi LELAC but strikingly deviated from the Ni−Ni bond in Ni foil (Fig. 2h and Supplementary Figs. 10a,11), indicating an atomic dispersion of Ni species in the GaInNiSn MELAC. Likewise, both FT-EXAFS (Fig. 2f) and WT spectra (Fig. 2i and Supplementary Fig. 10b) of the Sn K-edge illustrated the Sn−Ni/Ga scattering paths, which are difficult to distinguish given their similarity in k and R space. Furthermore, various scattering models were employed to fit the EXAFS curves (Supplementary Table 4) to identify the coordination environment of the GaInNiSn MELAC. In terms of the selection criteria35, Model 5 emerged as the most possible coordination configuration featuring the Sn−Ni scattering path in the first coordination shell, lending evidence to the presence of Ni–Sn interactions (Fig. 2g).

Catalytic depolymerization of polyolefin waste

Generally, reaction temperature and duration strongly influence the depolymerization process. At temperatures below 500 °C, incomplete C–C bond cleavage reduced the selectivity and STY of light olefins, whereas increasing the temperature to 600 °C induced deep cracking and aromatization, generating substantial CH and aromatic byproducts that further deteriorate the STY of light olefins (Supplementary Fig. 13)16, 21. Moreover, because the polypropylene was completely depolymerized within 3 minutes, further extension of the reaction time led to a decrease in the STY of light olefins to 129.9 mmol g −1 h−1 (Supplementary Fig. 14). In stark contrast to a conventional resistance furnace, induction heating provides rapid (heat-up rate > 100 °C s−1), uniform (surface temperature variation of ±5 °C), and precise (targeting the LAC directly) reaction conditions for polyolefin depolymerization (Supplementary Figs. 13−18)23. Notably, the processing time for polypropylene plastics under induction heating was approximately 3.0 minutes, while the equivalent quantity of plastic required over 35.5 minutes for processing in a resistance furnace (Supplementary Fig. 19 and Supplementary Table 5). By achieving a swift rise to the target depolymerization temperature, induction heating minimizes the exposure to low temperatures, thereby suppressing partial chain scission and random cleavage. It is observed that, under induction heating, residue weight percentage and CH selectivity were remarkably lower than those heated by a conventional resistance furnace (Supplementary Tables 5,6). Compared with this technique, Joule heating generally induces localized thermal inhomogeneities, triggering excessive side reactions (e.g., coking) that reduce the selectivity of the target product24. Microwave heating is constrained by the low dielectric loss of polyolefins, resulting in suboptimal energy efficiency and difficulty in controlling heating uniformity and reaction processes27.

Furthermore, the incorporation of Sn as a promoter into the GaIn LELAC improved the C H selectivity and STY in polypropylene depolymerization (Supplementary Fig. 12 and Supplementary Table 6). This is because Sn can reduce the surface tension of the LAC, as evidenced by the characterization section, and thereby expand the contact area between the liquid alloy and the solid plastic, facilitating an increase in available depolymerization sites of LACs36. Meanwhile, the incorporation of Ni, with a strong C–H bond activation capability, into GaIn LELAC is considered to improve the depolymerization performance. Nonetheless, the cage effect impedes effective distribution of Ni to the solid-liquid reaction interface, leading to a modest increase in the depolymerization process. Once incorporating Sn and Ni within the GaIn LELAC, the polyolefin depolymerization process is strikingly strengthened. At a reaction temperature of 500 °C, the GaInNiSn MELAC achieved a light olefin selectivity of 79.7% and a STY of 181.5 mmol g ⁻1 h⁻1, reaching 150% and 200% increases compared with those of the GaIn LELAC, respectively (Fig. 3a). Notably, 96.0% of the plastic were depolymerized (Supplementary Table 6), while the residual product was mainly composed of jet fuel hydrocarbons (C –C ) with minimal paraffins (C ) (Supplementary Figs. 20,21). As shown in Fig. 3a, although the S of the quaternary LAC shows a modest increase in comparison with ternary LACs, the quaternary GaInNiSn LAC yields an average improvement of 75.4% in the depolymerization performance in terms of STY of light olefins, highlighting the effectiveness of this S tuning strategy. When benchmarked against state-of-the-art catalysts, the GaInNiSn LAC is far ahead in terms of the STY and monomer selectivity (Fig. 3b and Supplementary Table 7). Notably, the STY of light olefins for the GaInNiSn MELAC (1 bar) is threefold that of CIE under atmospheric pressure (1 bar), even approaching the STY under high pressures (15 bar).

The applicability of the catalytic depolymerization process using the GaInNiSn MELAC under induction heating was validated using diverse pure polyolefins (Fig. 3c and Supplementary Table 8). Low-density PE (LDPE) and high-density PE (HDPE) were depolymerized to their monomer of C H , with selectivity of 38.6% and 43.7%, respectively. Meanwhile, polystyrene (PS) depolymerization yielded valuable short-chain olefins with a total selectivity of 77.9%, demonstrating that our strategy can even cleave the stable aromatic ring structure of PS. The GaInNiSn MELAC was also applied to structure-complex thermoplastic elastomers: block copolymer of ethylene-octene (POE) and triblock copolymer of styrene-butadiene-styrene (SBS). Strikingly, both POE and SBS were predominantly deconstructed to C H , with total olefin selectivity of 72.6% and 65.9%, respectively, underscoring the versatility of our strategy. Furthermore, the depolymerization of mixed pure polyolefin streams, challenging to separate because of their comparable density, was investigated37, 38. The depolymerization of pure polyolefin blends, specifically PP + LDPE, PP + HDPE, and PP + PS (1:1 mass ratio), yielded light olefin selectivities of 76.3%–86.2% and STYs of 142.7–178.2 mmol g ⁻1 h⁻1. Besides, the product distribution is susceptible to the composition of the blends. For instance, the blends containing PP with non-block copolymers (PE or PS) primarily yielded C H and C H , while those of PP with block copolymers (POE or SBS) predominantly generated C H and C H . The depolymerization of a six-component blend, comprising equal masses of the above pure polyolefins, produced light olefins with a selectivity of 74.9% and a STY of 143.4 mmol g ⁻1 h⁻1, still remarkably outperforming other technologies (Fig. 3b). The depolymerization capability of the GaInNiSn MELAC was further evaluated using real-world plastic wastes. These complex waste streams comprise a variety of polymers, additives, and contaminants (e.g., food residues, inks, and labels), which significantly exacerbate recycling challenges39, 40. Representative post-consumer plastic products from daily life were selected for testing, including food packaging bags, takeaway containers, milk bottles, reagent buckets, foam boxes, toothpaste tubes, and medical ziplock bags (Supplementary Fig. 22). As illustrated in Fig. 3d and Supplementary Table 9 , the GaInNiSn MELAC depolymerizes these untreated, commercially sourced plastic items into light olefins, with the selectivities approaching that obtained from pure polymers, ranging from 70.7% to 84.3%, despite their complex compositions and unknown contaminants. Notably, even when the aforementioned post-consumer plastic wastes were physically mixed in equal mass ratios to simulate a heterogeneous real-world waste, the depolymerization products achieved a light olefin selectivity of 72.8% with a STY of 145.3 mmol g ⁻1 h⁻1, comparable to those of the pure polyolefin blends (Fig. 3c). These results demonstrate the robustness of our strategy in directly depolymerizing real-world, contaminated, and blended polyolefin wastes into valuable light olefins without prior sorting and cleaning.

Thermogravimetric analysis-Fourier transform infrared spectroscopy-mass spectrometry (TGA-FTIR-MS) was conducted to reveal the performance enhancement mechanism. Notably, the reaction rate of the GaInNiSn MELAC was greater than that of the other samples on account of the increased solid-liquid contact area between plastics and LAC (Supplementary Fig. 23). The formation of =C–H peaks at low temperatures manifests that the interface-enriched Niδ⁻–Snδ+ sites contribute to C–H bond activation (Fig. 4a,b and Supplementary Figs. 24,25). The negatively charged Ni site in the GaInNiSn MELAC leads to strong H adsorption (Supplementary Fig. 26), reducing C–H activation barriers and boosting subsequent β-scission41. Furthermore, at 360–400 °C, the peak areas of =C–H and C=C bonds in the GaInNiSn MELAC were 2.6 and 2.3 times greater than those in the GaInNi LELAC, respectively (Fig. 4c), attesting to the robust capability of the Niδ⁻–Snδ+ sites to facilitate the β-scission of carbocation. Unlike other samples, light olefins and alkanes were simultaneously generated during the depolymerization process in the GaInNiSn MELAC (Fig. 4d,e, and Supplementary Fig. 27), further confirming the prevalence of β-scission. Generally speaking, the generation of short-chain hydrocarbons from PP pyrolysis primarily derives from the random cleavage of C–C bonds (Supplementary Fig. 28)38. In contrast, during the catalytic depolymerization of PP over the GaInNiSn MELAC, C–H bonds are first activated to form carbocation intermediates that subsequently undergo β-scission to produce light olefins (Fig. 4f)42, 43.

Photovoltaics-driven depolymerization system

To assess the scalability of this process for practical implementation, we constructed an outdoor photovoltaics-driven depolymerization system in Dalian City, Liaoning Province, China. As illustrated in Fig. 5a, the system comprises four photovoltaic panels (irradiation area of 10.3 m2, module efficiency of 24%), an electromagnetic induction heating apparatus (operating power 380 Wh), a vacuum heat pipe reactor, and four storage batteries with a combined capacity of 9.6 kWh. This system was loaded with 11.7 g of the GaInNiSn MELAC to recycle real-world polyolefin waste, consistent with the blends tested in Section 2.2. The real-world waste fragments are conveyed into the reactor via a continuous feed apparatus at a feed rate of 2.92 g min⁻1 (Supplementary Fig. 29). The process flow and unit schematics of the system are provided in Fig. 5b, with further details in the Methods section. The outdoor system operated continuously for 120 hours from 6th July to 20th July 2025 (daily from 08:30 to 16:30). Ambient temperatures during operation ranged from 22.3 to 28.1 °C, with outdoor solar irradiance recorded in Supplementary Fig. 30a. Despite fluctuations in photovoltaic output, the energy supply to the reactor remained stable due to the battery buffer (Supplementary Fig. 30b). As shown in Fig. 5c, the system achieved a light olefin production rate of 52.8 L h⁻1 and a selectivity of 71.5% (Supplementary Table 10), summing up 6337 L light olefins over 120 hours and thus suggesting excellent operational stability. The energy consumption of the depolymerization process by our system was calculated to be 3.8 kWh kg ⁻1. Notably, compared with other depolymerization technologies (Fig. 5d), our system offers over five times greater production rates and ten times longer stability, highlighting its significant advantages44. Furthermore, we conducted characterization analysis and performance testing on the recovered GaInNiSn MELAC (Supplementary Fig. 31–33 and Supplementary Tables 11,12). The results indicate no significant changes occur in surface morphology, elemental composition, and electronic structure compared with the fresh GaInNiSn MELAC. Meanwhile, the recovered GaInNiSn MELAC exhibited a light olefin selectivity of 78.1% and a STY of 178.8 mmol g −1 h−1 during the depolymerization of PP plastic. These values are equivalent to the catalytic performance of the fresh GaInNiSn MELAC, demonstrating the recoverability and reusability of the GaInNiSn MELAC.

Methods
Synthesis of liquid alloy catalyst (LAC). Nitrate salt powders and metallic particles were mixed in a graphite crucible and transferred to a tube furnace. Specifically, for preparing 1.95 g of GaInNiSn MELAC with a targeted element mass ratio of Ga:In:Ni:Sn = 30:15:3:2, the following reagents were accurately weighed as precursors: 1.170 g of metallic gallium granules (Ga), 0.585 g of metallic indium granules (In), 0.078 g of metallic tin granules (Sn), and 0.579 g of nickel nitrate hexahydrate (Ni(NO 3 ) 2 ·6H 2 O, corresponding to 0.117 g of Ni). These materials were thoroughly ground in an agate mortar for 5 minutes to ensure homogeneous mixing before being transferred to the graphite crucible. At ambient temperature, a constant flow of 60 mL min⁻1 N , regulated by a mass flow controller, was injected into the furnace for 10 min to remove air. The temperature of the LAC (during synthesis) was monitored by a K-type thermocouple controlled by a PID 679 controller. A 30 mL min⁻1 H stream, regulated by another mass flow controller, was then mixed with the 60 mL min⁻1 N stream and introduced into the furnace. The furnace was heated from ambient temperature to 380 °C at a heating rate of 5 °C min⁻1 and maintained at 380 °C for 1.5 hours. Subsequently, the LAC was prepared by annealing to 500 °C at a heating rate of 5 °C min⁻1 and subjecting it to slow reduction for 2 hours in a mixed atmosphere of H and N (total flow rate of 90 mL min⁻1, volume ratio of 1:2). After the LAC cooled to room temperature, it was stored in a sealed container.

Catalytic depolymerization. The indoor experimental setup is depicted in Supplementary Fig. 15, comprising a depolymerization reactor, a laser thermo-detector, a thermo-detector control box, an induction heating apparatus (Ambrell EASYHEAT 0224, operating at a frequency of 150−400 kHz, with a maximum output of 2.4 kW), and a gas chromatograph. As illustrated in Supplementary Fig. 16, a piece of quartz wool (0.23 g) was placed in a quartz tube with an inner diameter of 16 mm. Specifically, the quartz wool is used to hold the LAC and facilitates uniform gas flow through the reactor; this approach is consistent with standard experimental protocols reported in the literature34, 40. The LAC used in the depolymerization experiments (including GaIn, GaInSn, GaInNi, and GaInNiSn) all weighed 1.95 g. Unlike supported catalysts, the LAC forms a liquid layer (diameter 1.6 cm, height 0.15 cm) within the reactor (Supplementary Fig. 16c) and thus does not undergo agglomeration during heating. Moreover, the molten LAC cannot permeate into the quartz wool owing to its high surface tension (> 500 mN m−1). The micrometre-scale voids formed by the interwoven quartz wool form a capillary structure. For non-wetting interfaces, capillary forces act as repulsive forces, thereby impeding the penetration of the LAC into the quartz wool45. Furthermore, the polymer was placed above the LAC and thus did not make direct contact with the quartz wool in depolymerization processing (Supplementary Fig. 16b). As the density of the polymer is lower than that of the LAC, the polymer does not pass through the LAC. Meanwhile, we performed ICP-OES testing on the spent quartz wool after the reactions. The results confirm the absence of elements of the liquid alloy catalyst or polymer within the quartz wool (Supplementary Table 11). The polyolefin plastics used in this manuscript (including LDPE, HDPE, PP, PS, POE, and SBS) exhibited particle sizes in the range of 0.25–0.55 mm (i.e., 30–60 mesh). For real-world plastic waste (e.g., food packaging bags, take-away containers, drinking water bottle caps, milk bottles, beverage straws, toothpaste tubes, foam boxes, reagent buckets, and medical ziplock bags), according to previous studies, we shredded them into fragments with a diameter of less than 2 mm before use, without any further treatment40. The lower end of the quartz tube was connected to the nitrogen gas pipeline, and the other end was the gas outlet, which was connected to a gas chromatograph spectrometer (GC, for on-line testing) or to an aluminium foil gas collection bag (for off-line testing). Before the experiment, we calibrated the laser thermometer using a K-type thermocouple to correct systematic errors such as the emissivity of the LAC and quartz tube, the transmission and refraction of the quartz tube, and optical path loss, ensuring accurate laser thermometer readings. The calibrated laser thermometer was employed to measure the temperature of the LAC, with the laser spot position shown in Supplementary Fig. 17a. Furthermore, the temperature rise and fall curve during the induction heating process is shown in Fig S17b. The excellent electrical conductivity of the LAC enabled it to reach the reaction temperature within 5 seconds. After the induction heating apparatus was turned off, the temperature of LAC fell to 250 °C within 30 seconds. For a typical catalytic experiment, nitrogen gas was continuously purged at a flow rate of 20 mL min−1 for 10 min to exhaust residual air. A calibrated laser thermometer (measuring wavelength 1.6 μm, temperature range 250−1400 °C) was positioned 20 cm away from the reactor to record the LAC temperature, with the output power of the induction heating apparatus adjusted in real time to achieve constant-temperature heating. The cross-sectional area of the LAC was calculated as 37.7 mm2, significantly larger than the spot area of the laser thermometer (3.14 mm2). Considering the thermal conductivity of LAC reaches 23.7 W m−1·K−1, it can be thought that the overall temperature of the LAC is uniform under steady state (500 °C). Furthermore, we conducted COMSOL calculations to confirm the highly uniform temperature distribution of the LAC (Supplementary Fig. 18). Consequently, we can measure the temperature of the LAC accurately by positioning the spot of the laser thermometer on the surface of the LAC. Subsequently, a high-frequency electromagnetic induction unit was activated to drive the LAC to depolymerize the plastics. During the 3-minute heating process of the reactor, high-purity nitrogen was continuously introduced as the carrier gas at a flow rate of 4 mL min−1. As illustrated in Supplementary Fig. 15a, the nitrogen gas flowed from the bottom to the top of the quartz tube, ensuring that gaseous products formed were immediately swept away by the nitrogen stream and transferred to the gas collection bag, rather than remaining in continuous contact with the LAC. After the reaction proceeded for 3.0 min, the electromagnetic induction device was deactivated. Once the reactor was cooled to ambient temperature, the LAC was recovered with a pipette and sealed in a reagent bottle containing 2wt% acetone for subsequent testing (Supplementary Figs. 31,32 and Supplementary Tables 11,12). The recovered LAC can be reused after undergoing ultrasonic cleaning at 120 watts for 20 minutes (Supplementary Fig. 33). The conversion of plastic, the selectivity of light olefins, and the STY of light olefins were calculated using the following equations:

Conversion=( (M Reactor,0 - M Reactor,t) / M Plastic )×100% (1)

Selectivity=( X i / ∑n X i )×100% (2)

STY= ( ∑n Light olefins ) / ( M Liquid alloy × t ) (3)

where M Reactor,0 denotes the mass of the reactor before reaction (comprising the quartz tube, quartz wool, liquid alloy catalyst, and plastic), M Reactor,t denotes the mass of the reactor after reaction, and M Plastic denotes the mass of plastic added to the reactor before reaction; X i denotes the molar fraction of gas product i (including H , CH , C H , C H , C H , C H , C H , and C H ), and n is the number of gas products; ∑n Light olefins is the amount of light olefins (including C H , C H , and C H ) in millimoles, M Liquid alloy is the mass of the LAC in grams, and t is the reaction time in hours. The detailed conversion and mass balance analysis for the depolymerization reaction of polypropylene plastic is recorded in Supplementary Tables 13,14.

Application of an outdoor photovoltaics-driven depolymerization system. The outdoor photovoltaics-driven depolymerization system built in this study consisted of two components: a solar power system and a waste plastic depolymerization system. The solar power system used four TY-450M photovoltaic panels (2278 × 1134 × 30 mm) with an irradiation area of 10.3 m2 (module efficiency of 24%). Additionally, four 12 V−200 Ah storage batteries (storage capacity of 9.6 kWh) were equipped to store photovoltaic power, which is then converted by inverters for use in depolymerization reactions. Meanwhile, the batteries also stabilise power output and balance the effects of variations in weather and sunlight intensity46. The waste plastic depolymerization system used a customised vacuum heat pipe reactor, which comprised an outer pipe of 300 mm in length and 32 mm in diameter, an inner pipe of 450 mm in length and 20 mm in diameter, and a vacuum layer of 300 mm in length and 3 mm in thickness (Supplementary Fig. 29a). The vacuum heat pipe reactor was fixed using an aluminium bracket (dimensions: 330 × 350 × 650 mm). Subsequently, post-consumer plastic product fragments (e.g., food packaging bags, take-away containers, drinking water bottle caps, milk bottles, beverage straws, toothpaste tubes, foam boxes, reagent buckets, and medical ziplock bags) were loaded into the continuous feed apparatus and conveyed to the reactor via a screw rod at the left end of the apparatus (Supplementary Fig. 29b). The continuous feed apparatus delivers plastic fragments into the inner tube at a feed rate of 2.92 g min–1. For the production of light olefins (C H , C H , and C H ), 11.7 g of the GaInNiSn MELAC was used. The GaInNiSn MELAC was placed into the reactor only before the commencement of the reaction and was neither added nor removed during continuous operation. The induction heating apparatus was a JRHG-3 KW UHF ultra-high frequency induction heating machine (maximum output power: 3 kW; working frequency: 500−1100 kHz) supplied by Jinrui Intelligent Technology Co., Ltd. (Dongguan, Guangdong Province, China). The outdoor system was constructed on the top floor of the experimental building and operated continuously for over 120 hours between July 6th and July 20th, 2025 (daily from 8:30 to 16:30), with a reaction temperature of 500 °C and an ambient temperature ranging from 22.3 to 28.1 °C (Supplementary Fig. 30). The generated light olefins were collected in aluminium foil gas sampling bags, and their detailed composition and corresponding percentages were determined via GC-MS analysis (off-line mode).

First-Principles Calculations. Considering that GaInNi and GaInNiSn remained in a liquid state throughout the depolymerization process, ab initio molecular dynamics (AIMD) simulations were performed to obtain reasonable equilibrium configurations for both systems. Before the AIMD simulation, 100 atoms with target compositions were randomly generated for each alloy using PACKMOL in a 13 Å × 13 Å × 25 Å periodic box. To eliminate spurious periodic interactions between adjacent systems and accommodate the thermal mobility of liquid atoms, a 15 Å vacuum layer was added along the height direction of the 25 Å box, resulting in a slab model of the final periodic box size of 13 Å × 13 Å × 40 Å for the formal AIMD simulations. The target compositions of the two alloy systems were as follows: GaInNi (Ga:In:Ni = 67:19:14) and GaInNiSn (Ga:In:Ni:Sn = 69:20:8:3). Notably, all these details (the number of atoms and the cell dimensions) are now explicitly stated in the corresponding figure captions for the AIMD snapshots. For the AIMD simulations, the plane-wave cutoff energy was set to 520 eV; a 1 × 1 × 1 k-mesh was used to sample the Brillouin zone, and spin-orbit coupling (SOC) was taken into account in the calculations47. The samples were then equilibrated at the equilibrium temperature (773 K) for 10 ps in the canonical ensemble (NVT). The time step was chosen to be 2 fs, and the integration of Newton’s equation was based on the Verlet algorithm implemented in the Vienna Ab-initio Simulation Package (VASP). Subsequently, suitable atomic configurations with active sites proximal to the surface were selected from the 10 ps AIMD trajectories, and periodic plane-wave density functional theory (DFT) calculations were performed on GaInNi and GaInNiSn using the VASP (VASP 6.3.2 optcell)48. To investigate the activation mechanism of C−H bonds, the H adsorption energy on the active Ni sites in the two systems was calculated. The projector augmented plane wave (PAW) pseudopotential basis set and the generalized gradient approximation (GGA) functional with the Perdew–Burke–Ernzerhof (PBE) parametrization were employed in these calculations. A kinetic energy cutoff of 520 eV for plane-wave expansion was used for the two systems. Brillouin zone sampling was performed using a 3 × 1 × 3 k-point grid centred at the Γ point. The force convergence criterion was set to 0.02 eV Å⁻1, and spin-orbit coupling effects were considered in the calculations. A 15 Å vacuum layer was introduced to avoid the influence of adjacent crystal planes on surface atoms, and the top atomic layers (surface region) were fully relaxed.

Peer review rounds
[{"round": 1, "reviewer_comments": {"reviewer_1": "This manuscript describes a novel approach to the depolymerization of waste PP and PE, as well as their mixtures, to produce a mixture of light olefins Pulsed RF heating to 500oC for 3 min in the presence of a liquid alloy catalyst (LAC), preferably GaInNiSn (MELAC) is shown to achieve a high degree of polymerization. The authors show that GaIN acts as a solvent for Ni and Sn and that Sn enables the segregation of Ni --Sn + sites to the surface of the catalyst in its as-prepared state. It is reported that for PP, a space time yield (STY) of 181.5 mmol gcat-1 h-1 can be achieved with a 79.7% yield of light olefins. Low-density PE (LDPE) and high-density PE (HDPE) were depolymerized to their monomer of C2H4, with selectivity of 38.6% and 43.7%, respectively. Additionally, the authors report the construction of an outdoor photovoltaics-driven depolymerization system with an annual capacity of 1.23 tons of real-world polyolefin waste, which can maintain light olefin production at a rate of 52.8 L h-1 for more than 120 h of continuous operation.\nThis is an interesting manuscript deserving publication once the authors address the issues posed below.\n1. The experimental section of the manuscript notes that depolymerization was carried out in a 16 mm ID quartz tube connected to a source of N2 that could be used flush air from the reactor prior to the onset of reaction and to flush gaseous and condensable products from the reactors after reaction. What is not stated but should be is whether the gaseous products produced during the 3 min that the reactor is heated remain in contact with the catalyst. It is also not clear what the purpose is of adding a piece of aluminosilicate refractory fiber to the vial. How much fiber is added and what is its role? Does the fiber absorb the molten catalyst or polymer?\n2. No information is given about the size of the catalyst or polymer particles added to the reactor. Do the catalyst particles agglomerate once they melt and do they wick into the aluminosilicate? Can the catalyst be recovered and reused after an experiment.\n3. The calculation of STY used is misleading since it is based on the total weight of catalyst added to the reactor and not on the amount of catalyst that is active. For example, if one considers the catalysts used for cracking-isomerization-ethenolysis reported Ref. 25, the STY these catalysts reported as 5-16 mmol gcat-1 h-1 in Table S5. Recognizing the Wo3/SiO2 catalyst controls the rate of the CIE process after the few minutes of the reaction then one can estimate the STY for this catalyst if 62.5 to 200 mmol gcat-1 h-1, which is the in the same order of magnitude as the STY MELAC catalyst used in the present study. Therefore, the results presented in Fig. 3b need to be corrected for the STY. Also, the rate expressed as mg/min is a function of the amount of catalyst used and not solely the intrinsic activity of each catalyst. Thus, it would be more appropriate to plot the corrected STY vs olefin selectivity and polymer conversion. However, one must keep in mind that STY as defined is very crude indicator of relative activity, since it represents the cumulative conversion for a given catalyst operated under specific conditions. Hence, part of the high STY reported by the authors is due to the operation of their catalyst at 500oC and is not a valid base for comparing the intrinsic activity of different catalysts.\n4. The outdoor photovoltaics-driven depolymerization system is inadequately described. No indication is given of the type of reactor is used, how the polymer is fed to the reactor, and how long the polymer is heated and to what temperature. This is unacceptable. It is suggested that the authors should either leave out this part of the text in this manuscript and present a more thorough description in a separate manuscript. With significantly more information, the critical reader is left with too many unanswered questions. The same is true for the techno-economic analysis. The reliability of such analyses hinges on many assumptions, and the evidence supporting them. This part of the text is too short to judge whether the authors projections for the economic viability of their process are realistic.\nIn summary, this manuscript presents an interesting alternative for the depolymerization of waste olefins and its novelty justifies its publication once the concerns expressed above have been addressed and the revised manuscript has been reviewed.", "reviewer_2": "The manuscript by Xu et al. presents a new depolymerization catalyst for polyolefin waste based on a quarternary alloy GaInNiSn. The topic of the manuscript is highly relevant and the catalyst presented in the manuscript seems to work well. The catalyst was not only used at the lab scale but in a 'real-word' setup. The GaInNiSn alloy is characterized very well by state-of-the-art characterization techniques.\nThe manuscript in its present form, however, makes it difficult to judge whether it is suitable for Nature Communications because crucial information is not provided. The key claim of the authors is that their catalyst has a distinctively higher space-time yield than competing known catalysts. Figure 1a shows that the GaInNiSn catalyst has a somewhat but not dramatically increased space-time yield compared to GaInNi catalyst. In so far, the improvement is more incremental.\nA crucial shortcoming of the manuscript is that the catalyst setup is not really described. The GaInNiSn alloy is liquid at reaction temperatures. Is the liquid alloy used on some sort of support. If yes, what support is used and in what form the liquid alloy is on the support, droplets of a certain size or otherwise? How does the actual reaction setup looks like? How is the space-time yield calculated? With respect only to the amount of liquid alloy? This would be misleading, the complete catalyst including support needs to be considered.\nThe ab-initio MD calculation are not sufficiently describe. Is a slab model used? What unit cells are used with how many atoms. In the SI a figure on the ab-initio MD shows a very small number of atoms which would be to small to draw substantial conclusions.\nIn summary the manuscript shows interesting results but, at present, it is not possible to judge whether the manuscript is suitable for Nature Communications and before publication in any journal the points mentioned above need to be taken care of.", "reviewer_3": "This paper reports on the transformation of polyolefins into light olefins under atmospheric pressure, utilizing an induction heating and a quaternary GaInNiSn medium-entropy liquid alloy catalyst (MELAC). Through an interfacial configurational entropy regulation strategy, the catalyst forms Ni\\delta\\minus\\text{--}Sn\\delta+ active sites, which facilitate C\\text{--}H bond activation and \\beta-scission. This strategy enhances the depolymerization performance, achieving a high space-time yield of 181.5 mmol gcat\\minus1 h\\minus1 and a selectivity of 79.7% for the transformation of PP into light olefins. Furthermore, the study demonstrates a photovoltaic-driven, outdoor continuous depolymerization system, to support its feasibility in processing real-world plastic wastes. The study provides a method for efficient recycling of waste polyolefin plastics, still some important issues should be resolved prior accepting the manuscript for publication.\n1. Has the reaction system been temperature-corrected? How to ensure that at the fixed position of the laser thermometer, the temperature at the reaction site can be accurately measured?\n2. More control experiments should be conducted to make the effect of the MELAC clearer. For example, the performance of control group should be evaluated at different temperatures and reaction times. Also, the temperature of different LAC under induction heating should be carefully compared.\n3. The performance and structure of spent catalyst needs to be explored in detail.\n4. More experimental details of the outdoor photovoltaics-driven depolymerization system should be provided. For example, the “continuous operation” is actually intermittent, as can be inferred from the conditions of “500 °C for 3 min (each reaction)” in the legend of Figure 5c. Also, the rate and selectivity were almost unchanged within 120 hours, which is impossible considering the difference of light intensities during the day and at night. As an outdoor photovoltaics-driven experiment, the specific date and time need to be provided. In addition, it is necessary to clarify whether 8.77 g of plastics and 11.69 g of “fresh” catalysts need to be added in each reaction during the “continuous operation”. Taking into account the discontinuity of the experiment and the very limited and specific testing time, it is not recommended to claim that an outdoor photovoltaics-driven depolymerization system with an annual capacity of 1.23 tons has been constructed.\n5. It seems that compared to electric furnace heating, the major advantage of induction heating lies in the transient variation of temperature. Therefore, it is recommended to conduct a further discussion among different instantaneous heating technologies.\n6. It is suggested to provide data of conversion and mass/carbon balance."}, "author_response": "Ref. No.: NCOMMS-25-93184\nTitle: Interfacial Configurational Entropy Tuning Strategy Enabling Liquid Alloys for\nEfficient Depolymerization of Polyolefin Waste\nWe sincerely appreciate the editor and all the reviewers for their efforts and insightful comments, and\nwe respond in a point-by-point manner below.\n-1-\nReviewer #1:\nThis manuscript describes a novel approach to the depolymerization of waste PP and PE, as well as their\nmixtures, to produce a mixture of light olefins Pulsed RF heating to 500 °C for 3 min in the presence of a\nliquid alloy catalyst (LAC), preferably GaInNiSn (MELAC) is shown to achieve a high degree of\npolymerization. The authors show that GaIN acts as a solvent for Ni and Sn and that Sn enables the\nsegregation of Ni\\delta\\minus\\text{--}Sn\\delta+ sites to the surface of the catalyst in its as-prepared state. It is reported that for\nPP, a space time yield (STY) of 181.5 mmol g \\minus1 h\\minus1 can be achieved with a 79.7% yield of light olefins.\ncat\nLow-density PE (LDPE) and high-density PE (HDPE) were depolymerized to their monomer of C H ,\n2 4\nwith\nselectivity of 38.6% and 43.7%, respectively. Additionally, the authors report the construction of an\noutdoor photovoltaics-driven depolymerization system with an annual capacity of 1.23 tons of real-\nworld polyolefin waste, which can maintain light olefin production at a rate of 52.8 L h\\minus1 for more than\n120 h of continuous operation. This is an interesting manuscript deserving publication once the authors\naddress the issues posed below:\nResponse: Many thanks to the reviewer for the careful review of our manuscript. The constructive\nconcerns provided have been invaluable in enhancing the quality of our work. We deeply appreciate the\nopportunity to address these insightful questions. Each of your comments has been carefully considered,\nleading us to enhance our manuscript by incorporating detailed explanations and improvements across\nall the points you raised.\n1. The experimental section of the manuscript notes that depolymerization was carried out in a 16\nmm ID quartz tube connected to a source of N that could be used flush air from the reactor prior\n2\nto the onset of reaction and to flush gaseous and condensable products from the reactors after\nreaction. What is not stated but should be is whether the gaseous products produced during the 3\nmin that the reactor is heated remain in contact with the catalyst. It is also not clear what the\npurpose is of adding a piece of aluminosilicate refractory fiber to the vial. How much fiber is added\nand what is its role? Does the fiber absorb the molten catalyst or polymer?\n1.1. The experimental section of the manuscript notes that depolymerization was carried out in a 16\nmm ID quartz tube connected to a source of N that could be used flush air from the reactor prior\n2\n-2-\nto the onset of reaction and to flush gaseous and condensable products from the reactors after\nreaction. What is not stated but should be is whether the gaseous products produced during the 3\nmin that the reactor is heated remain in contact with the catalyst.\nResponse: We genuinely thank you for your constructive suggestions and deeply apologise for the\nambiguities in the descriptive content of the Methods section in the manuscript. The gaseous products\ngenerated during the 3-minute heating process do not remain in contact with the catalyst. Indeed, during\nthe heating process, high-purity nitrogen was continuously introduced as the carrier gas at a flow rate of\n4 mL min\\minus1. As illustrated in Response Fig. 1, the carrier gas flow from the bottom to the top of the quartz\ntube, ensuring that gaseous products formed are immediately swept away by the nitrogen stream and\ntransferred to the gas collection bag, rather than remaining in continuous contact with the catalyst.\nResponse Fig. 1. Depolymerization reactor setup. (a) Gas flow: nitrogen gas flow (orange) and gaseous\nproduct stream (blue). (b) Localised magnification of the depolymerization reaction zone in side view,\ncomprising polypropylene plastic, liquid alloy catalyst, and quartz wool. The quartz wool (0.23 g, 0.76 cm)\nis used to support the liquid alloy catalyst (1.95 g, 0.15 cm). The polypropylene plastic (1.00 g) is placed\non top of the liquid alloy, with a stacking height of 1.10 cm. (c) Localised magnification of the liquid alloy\ncatalyst from top view.\nTo illustrate this point, we have revised the Methods section in the manuscript (Page 14, Line 313\\minus317\n-3-\nand Line 325\\minus331):\nFor a typical catalytic experiment, nitrogen gas was continuously purged at a flow rate of 20 mL min\\minus1\nfor 10 min to exhaust residual air. Subsequently, a high-frequency electromagnetic induction unit was\nactivated to drive the LAC to depolymerize the plastics. During the 3-minute heating process of the\nreactor, high-purity nitrogen was continuously introduced as the carrier gas at a flow rate of 4 mL min\\minus1.\nAs illustrated in Fig. S16a, the nitrogen gas flowed from the bottom to the top of the quartz tube, ensuring\nthat gaseous products formed were immediately swept away by the nitrogen stream and transferred to\nthe gas collection bag, rather than remaining in continuous contact with the LAC. After the reaction\nproceeded for 3.0 min, the electromagnetic induction device was deactivated.\nWe have added Fig. S16 in the supporting information:\nFig. S16. Depolymerization reactor setup. (a) Gas flow: nitrogen gas flow (orange) and gaseous product\nstream (blue). (b) Localised magnification of the depolymerization reaction zone in side view, comprising\npolypropylene plastic, liquid alloy catalyst, and quartz wool. The quartz wool (0.23 g, 0.76 cm) is used to\nsupport the liquid alloy catalyst (1.95 g, 0.15 cm). The polypropylene plastic (1.00 g) is placed on top of\nthe liquid alloy, with a stacking height of 1.10 cm. (c) Localised magnification of the liquid alloy catalyst\nfrom top view.\nACTION: Manuscript and Supporting Information amended\n-4-\n1.2. It is also not clear what the purpose is of adding a piece of aluminosilicate refractory fiber to the\nvial. How much fiber is added and what is its role? Does the fiber absorb the molten catalyst or\npolymer?\nResponse: We appreciate the reviewer's insightful comment and sincerely apologise for the incomplete\ninformation in the Methods section of the manuscript. Firstly, the liquid alloy catalyst was placed on a\nsmall piece of aluminosilicate refractory fibre inside the quartz tube to hold the LAC catalyst and\ndistribute gas flow (Response Fig. 1). Secondly, in our experiment, we added 0.23 g of aluminosilicate\nrefractory fibre. Finally, the aluminosilicate refractory fibre does not absorb the molten catalyst or\npolymer.\nSpecifically, aluminosilicate refractory fibres were used to hold the liquid alloy catalyst and facilitate\nuniform gas flow through the reactor, and this approach is consistent with standard experimental\nprotocols reported in the literature1, 2. As illustrated in Response Fig. 1, the liquid alloy catalyst cannot\npermeate into the aluminosilicate fibres owing to its high surface tension (> 500 mN m\\minus1). Moreover, the\nmicrometre-scale voids formed by the interwoven quartz wool constitute a capillary structure. For a non-\nwetting interface, capillary forces act as repulsive forces, thereby impeding the penetration of the liquid\nalloy catalyst into the aluminosilicate fibre3. Furthermore, the polymer was placed above the liquid alloy\ncatalyst and thus did not make direct contact with the quartz wool in depolymerization processing\n(Response Fig. 1). As the density of the polymer is lower than that of the liquid alloy catalyst, the polymer\ncannot pass through the liquid alloy catalyst. Meanwhile, we performed ICP-OES testing on the spent\nquartz wool after the reactions. The results confirm the absence of elements of the liquid alloy catalyst\nor polymer within the quartz wool (Response Table 1).\n-5-\nResponse Fig. 1. Depolymerization reactor setup. (a) Gas flow: nitrogen gas flow (orange) and gaseous\nproduct stream (blue). (b) Localised magnification of the depolymerization reaction zone in side view,\ncomprising polypropylene plastic, liquid alloy catalyst, and quartz wool. The quartz wool (0.23 g, 0.76 cm)\nis used to support the liquid alloy catalyst (1.95 g, 0.15 cm). The polypropylene plastic (1.00 g) is placed\non top of the liquid alloy, with a stacking height of 1.10 cm. (c) Localised magnification of the liquid alloy\ncatalyst from top view.\nResponse Table 1. ICP-OES elemental analysis of spent quartz wool\nElement Weight percentage (wt%)\nGa /\nIn /\nNi /\nSn /\nSi 100\nTo explain this issue, we have added Fig. S16 and Table S10 to the supplementary information and revised\nthe Methods section of the manuscript to explicitly specify the role and amount of the quartz wool. To\navoid ambiguity, we have replaced all the terminology “aluminosilicate refractory fibre” with “quartz\n-6-\nwool” in both the manuscript and the supporting information.\nWe have updated the Methods section in the manuscript (Page 13, Line 291\\minus305) and Fig. S16 and\nTable S10 in the supporting information:\nAs illustrated in Fig. S16b, a piece of quartz wool (0.23 g) was placed in a quartz tube with an inner\ndiameter of 16 mm. Specifically, the quartz wool is used to hold the LAC and facilitates uniform gas flow\nthrough the reactor; this approach is consistent with standard experimental protocols reported in the\nliterature1, 2. The LAC used in the depolymerization experiments (including GaIn, GaInSn, GaInNi, and\nGaInNiSn) all weighed 1.95 g. Unlike supported catalysts, the LAC forms a liquid layer (diameter 1.60 cm,\nheight 0.15 cm) within the reactor (Fig. S16c) and thus does not undergo agglomeration during heating.\nMoreover, the molten LAC cannot permeate into the quartz wool owing to its high surface tension (> 500\nmN m\\minus1). The micrometre-scale voids formed by the interwoven quartz wool form a capillary structure.\nFor non-wetting interfaces, capillary forces act as repulsive forces, thereby impeding the penetration of\nthe LAC into the quartz wool3. Furthermore, the polymer was placed above the LAC and thus did not make\ndirect contact with the quartz wool in depolymerization processing (Fig. S16b). As the density of the\npolymer is lower than that of the LAC, the polymer does not pass through the LAC. Meanwhile, we\nperformed ICP-OES testing on the spent quartz wool after the reactions. The results confirm the absence\nof elements of the liquid alloy catalyst or polymer within the quartz wool (Table S10).\n-7-\nFig. S16. Depolymerization reactor setup. (a) Gas flow: nitrogen gas flow (orange) and gaseous product\nstream (blue). (b) Localised magnification of the depolymerization reaction zone in side view, comprising\npolypropylene plastic, liquid alloy catalyst, and quartz wool. The quartz wool (0.23 g, 0.76 cm) is used to\nsupport the liquid alloy catalyst (1.95 g, 0.15 cm). The polypropylene plastic (1.00 g) is placed on top of\nthe liquid alloy, with a stacking height of 1.10 cm. (c) Localised magnification of the liquid alloy catalyst\nfrom top view.\nTable S10. ICP-OES elemental analysis of spent quartz wool\nElement Weight percentage (wt%)\nGa /\nIn /\nNi /\nSn /\nSi 100\nACTION: Manuscript and Supporting Information amended\n2. No information is given about the size of the catalyst or polymer particles added to the reactor. Do\nthe catalyst particles agglomerate once they melt and do they wick into the aluminosilicate? Can\nthe catalyst be recovered and reused after an experiment.\n2.1. No information is given about the size of the catalyst or polymer particles added to the reactor.\nResponse: We thank the reviewers for their constructive suggestions and apologise for the\nincompleteness of the information regarding the catalyst and polymers.\nThe liquid alloy catalyst employed in the manuscript remains liquid at room temperature. The liquid alloy\ncatalysts used in the depolymerization experiments (including GaIn, GaInSn, GaInNi, and GaInNiSn) all\nweighed 1.95 g. Unlike supported catalysts, the LAC forms a liquid layer (diameter 1.60 cm, height 0.15\ncm) within the reactor (Fig. S16c) and thus does not undergo agglomeration during heating. The\n-8-\npolyolefin plastics used in this manuscript (including LDPE, HDPE, PP, PS, POE, and SBS) exhibited particle\nsizes in the range of 0.25\\text{--}0.55 mm (i.e., 30\\text{--}60 mesh). For real-world plastic waste (e.g., food packaging\nbags, take-away containers, drinking water bottle caps, milk bottles, beverage straws, toothpaste tubes,\nfoam boxes, reagent buckets, and medical ziplock bags), according to previous studies, we shredded them\ninto fragments with a diameter of less than 2 mm before use, without any further treatment2.\nWe have updated the Methods section of the manuscript to reflect the size of LAC (Page 13, Line\n294\\minus297)\nThe LAC used in the depolymerization experiments (including GaIn, GaInSn, GaInNi, and GaInNiSn) all\nweighed 1.95 g. Unlike supported catalysts, the LAC forms a liquid layer (diameter 1.60 cm, height 0.15\ncm) within the reactor (Fig. S16c) and thus does not undergo agglomeration during heating.\nWe have updated the Methods section of the manuscript to reflect the size of polymer particles (Page\n14, Line 305\\minus310):\nThe polyolefin plastics used in this manuscript (including LDPE, HDPE, PP, PS, POE, and SBS) exhibited\nparticle sizes in the range of 0.25\\text{--}0.55 mm (i.e., 30\\text{--}60 mesh). For real-world plastic waste (e.g., food\npackaging bags, take-away containers, drinking water bottle caps, milk bottles, beverage straws,\ntoothpaste tubes, foam boxes, reagent buckets, and medical ziplock bags), according to previous studies,\nwe shredded them into fragments with a diameter of less than 2 mm before use, without any further\ntreatment2.\nACTION: Manuscript and Supporting Information amended\n2.2. Do the catalyst particles agglomerate once they melt and do they wick into the aluminosilicate?\nResponse: We thank the reviewer for this critical comment and sincerely apologise for the insufficiency\nof the Methods description. The liquid alloy catalyst employed in the manuscript remains liquid at room\ntemperature. It neither agglomerates nor permeates into the aluminosilicate fibres after melting.\nUnlike supported catalysts, liquid alloy catalysts form a liquid layer (diameter 1.60 cm, height 0.15 cm)\nwithin the reactor (Response Fig. 1) and thus do not undergo agglomeration during heating. Moreover,\n-9-\nthe molten catalyst cannot permeate into the aluminosilicate fibres owing to its high surface tension.\nThe micrometre-scale voids formed by the interwoven aluminosilicate fibres form a capillary structure.\nFor non-wetting interfaces, capillary forces act as repulsive forces, thereby impeding the penetration of\nliquid alloy catalyst into the aluminosilicate fibres3. In addition, ICP-OES analysis showed that characteristic\nelements of the liquid alloy catalyst were not detected in the aluminosilicate fibres after reactions\n(Response Table 1).\nResponse Fig. 1. Depolymerization reactor setup. (a) Gas flow: nitrogen gas flow (orange) and gaseous\nproduct stream (blue). (b) Localised magnification of the depolymerization reaction zone in side view,\ncomprising polypropylene plastic, liquid alloy catalyst, and quartz wool. The quartz wool (0.23 g, 0.76 cm)\nis used to support the liquid alloy catalyst (1.95 g, 0.15 cm). The polypropylene plastic (1.00 g) is placed\non top of the liquid alloy, with a stacking height of 1.10 cm. (c) Localised magnification of the liquid alloy\ncatalyst from top view.\nResponse Table 1. ICP-OES elemental analysis of spent quartz wool\nElement Weight percentage (wt%)\nGa /\nIn /\n-10-\nNi /\nSn /\nSi 100\nTo illustrate this point, we have updated the Methods section of the manuscript (Page 13, Line 295\\minus303)\nand included Fig. S16 and Table S10 in the supporting information to show the morphology of the liquid\nalloy catalyst after melting:\nUnlike supported catalysts, the LAC formed a liquid layer (diameter 1.60 cm, height 0.15 cm) within the\nreactor (Fig. S16c) and thus did not undergo agglomeration during heating. Moreover, the molten LAC\ncannot permeate into the quartz wool owing to its high surface tension (> 500 mN m\\minus1). The micrometre-\nscale voids formed by the interwoven quartz wool form a capillary structure. For non-wetting interfaces,\ncapillary forces act as repulsive forces, thereby impeding the penetration of the LAC into the quartz wool3.\nFurthermore, the polymer was placed above the LAC and thus did not make direct contact with the quartz\nwool in depolymerization processing (Fig. S16b). As the density of the polymer is lower than that of the\nliquid alloy catalyst, the polymer does not pass through the LAC.\nFig. S16. Depolymerization reactor setup. (a) Gas flow: nitrogen gas flow (orange) and gaseous product\nstream (blue). (b) Localised magnification of the depolymerization reaction zone in side view, comprising\npolypropylene plastic, liquid alloy catalyst, and quartz wool. The quartz wool (0.23 g, 0.76 cm) is used to\n-11-\nsupport the liquid alloy catalyst (1.95 g, 0.15 cm). The polypropylene plastic (1.00 g) is placed on top of\nthe liquid alloy, with a stacking height of 1.10 cm. (c) Localised magnification of the liquid alloy catalyst\nfrom top view.\nTable S10. ICP-OES elemental analysis of spent quartz wool\nElement Weight percentage (wt%)\nGa /\nIn /\nNi /\nSn /\nSi 100\nACTION: Manuscript and Supporting Information amended\n2.3. Can the catalyst be recovered and reused after an experiment.\nResponse: We appreciate the reviewer's valuable suggestion. We have demonstrated that the liquid alloy\ncatalyst employed in the manuscript is recoverable and reusable through multiple characterisation\ntechniques and performance tests.\nThe liquid alloy catalyst was recovered with a pipette and sealed in a reagent bottle containing 2wt%\nacetone for subsequent testing. The recovered LAC can be reused after undergoing ultrasonic cleaning at\n120 watts for 20 minutes. We characterised the structure and morphology of the recovered GaInNiSn\nMELAC after a 120-hour stability test. Firstly, we performed high-angle annular dark field scanning TEM\n(HAADF-STEM) analysis on the recovered GaInNiSn MELAC (Response Fig. 2). The results indicate that the\nmorphology of the recovered GaInNiSn MELAC remained almost unchanged after 120 h of operation in\nthe plastic depolymerization reaction, without Ni agglomeration observed. Secondly, the weight\npercentages of elements in the recovered GaInNiSn MELAC measured by inductively coupled plasma-\noptical emission spectrometry (ICP-OES) showed no significant variation in comparison with the fresh\n-12-\nsample (Response Table 2). XPS analysis confirms that the recovered GaInNiSn MELAC exhibited no\nsignificant changes in electronic structure compared with the fresh sample (Response Fig. 3). Finally, the\ndepolymerization performance of the recovered GaInNiSn MELAC showed a light olefin selectivity of 78.1%\nand a space-time yield of 178.8 mmol g \\minus1 h\\minus1 (Response Fig. 4), which are equivalent to those of fresh\ncat\nGaInNiSn MELAC. These characterisations and experiments demonstrate the recoverability and\nreusability of our designed GaInNiSn MELAC.\nResponse Fig. 2. HAADF-STEM image and corresponding EDS mapping of the recovered GaInNiSn MELAC.\n-13-\nResponse Fig. 3. XPS spectra of fresh and recovered GaInNiSn MELACs.\nResponse Fig. 4. Depolymerization performance of fresh and recovered GaInNiSn MELACs. Reaction\nconditions: 1.00 g of polypropylene plastic, 1.95 g of recovered GaInNiSn MELAC, N feed gas at a flow\n2\nrate of 4 mL min\\text{--}1, and 500 °C for 3 min.\n-14-\nResponse Table 2. ICP-OES elemental analysis of fresh and recovered GaInNiSn MELACs\nSample Element Weight percentage (wt%)\nGa 61.23\nIn 28.69\nFresh GaInNiSn MELAC\nNi 6.01\nSn 4.07\nGa 62.15\nIn 27.84\nRecovered GaInNiSn MELAC\nNi 6.29\nSn 3.72\nWe have updated Section 2.3 of the manuscript (Page 11, Line 251–257):\nFurthermore, we conducted characterisation analysis and performance testing on the spent quartz wool\nand the recovered GaInNiSn MELAC (Figs. S30–S32 and Tables S10,S11). The results indicate no significant\nchange in surface morphology, elemental composition, and electronic structure compared with the fresh\nGaInNiSn MELAC. Meanwhile, the recovered GaInNiSn MELAC exhibited a 78.1% light olefin selectivity\nand a 178.8 mmol g \\minus1 h\\minus1 STY during the depolymerization of PP plastic. These values were equivalented\ncat\nto the catalytic performance of the fresh GaInNiSn MELAC, demonstrating the recoverability and\nreusability of the GaInNiSn MELAC.\nWe have updated the Methods section of the manuscript (Page 15, Line 331–334):\nOnce the reactor was cooled to ambient temperature, the LAC was recovered with a pipette and sealed\nin a reagent bottle containing 2wt% acetone for subsequent testing (Figs. S30,S31 and Tables S10,S11).\nThe recovered LAC can be reused after undergoing ultrasonic cleaning at 120 watts for 20 minutes (Fig.\nS32).\n-15-\nWe have updated Figs. S30–S32 and Table S11 in the supporting information:\nFig. S30. HAADF-STEM image and corresponding EDS mapping of the recovered GaInNiSn MELAC.\n-16-\nFig. S31. XPS spectra of fresh and recovered GaInNiSn MELACs.\nFig. S32. Depolymerization performance of fresh and recovered GaInNiSn MELACs. Reaction conditions:\n1.0 g of polypropylene plastic, 1.95 g of recovered GaInNiSn MELAC, N feed gas at a flow rate of 4 mL\n2\nmin\\text{--}1, and 500 °C for 3 min.\nTable S11. ICP-OES elemental analysis of fresh and recovered GaInNiSn MELACs\nSample Element Weight percentage (wt%)\nGa 61.23\nIn 28.69\nFresh GaInNiSn MELAC\nNi 6.01\nSn 4.07\nGa 62.15\nRecovered GaInNiSn MELAC\nIn 27.84\n-17-\nNi 6.29\nSn 3.72\nACTION: Manuscript and Supporting Information amended\n3. The calculation of STY used is misleading since it is based on the total weight of catalyst added to\nthe reactor and not on the amount of catalyst that is active. For example, if one considers the\ncatalysts used for cracking-isomerization-ethenolysis reported Ref. 25, the STY these catalysts\nreported as 5-16 mmol g \\minus1 h\\minus1 in Table S5. Recognizing the Wo /SiO catalyst controls the rate of\ncat 3 2\nthe CIE process after the few minutes of the reaction then one can estimate the STY for this catalyst\nif 62.5 to 200 mmol g \\minus1 h\\minus1, which is the in the same order of magnitude as the STY MELAC catalyst\ncat\nused in the present study. Therefore, the results presented in Fig. 3b need to be corrected for the\nSTY. Also, the rate expressed as mg/min is a function of the amount of catalyst used and not solely\nthe intrinsic activity of each catalyst. Thus, it would be more appropriate to plot the corrected STY\nvs olefin selectivity and polymer conversion. However, one must keep in mind that STY as defined\nis very crude indicator of relative activity, since it represents the cumulative conversion for a given\ncatalyst operated under specific conditions. Hence, part of the high STY reported by the authors is\ndue to the operation of their catalyst at 500 °C and is not a valid base for comparing the intrinsic\nactivity of different catalysts.\nResponse: We sincerely appreciate the reviewer's insightful comment regarding the space-time yield (STY)\nof the catalyst. We fully endorse the reviewer's comment and agree that plotting the relationship\nbetween the corrected STY, light olefin selectivity, and polymer conversion is an ideal approach for\ncomparing catalytic performance.\nFor the STY calculation, it should be clarified that the aluminosilicate fibre (quartz wool) serves merely\nto hold the catalyst as widely used in lab-scale fixed-bed tests, instead of a support for the liquid metal\ncatalyst. Unlike the SiO in WO /SiO , the aluminosilicate fibre itself is not a part of the catalyst, as\n2 3 2\nillustrated in Response Fig. 1b. Consequently, we used the total mass of the liquid alloy (1.95 g) without\nfibres in our STY calculations, which was 181.5 mmol g \\minus1 h\\minus1.\ncat\n-18-\nResponse Fig. 1. Depolymerization reactor setup. (a) Gas flow: nitrogen gas flow (orange) and gaseous\nproduct stream (blue). (b) Localised magnification of the depolymerization reaction zone in side view,\ncomprising polypropylene plastic, liquid alloy catalyst, and quartz wool. The quartz wool (0.23 g, 0.76 cm)\nis used to support the liquid alloy catalyst (1.95 g, 0.15 cm). The polypropylene plastic (1.00 g) is placed\non top of the liquid alloy, with a stacking height of 1.10 cm. (c) Localised magnification of the liquid alloy\ncatalyst from top view.\nFor the depolymerization rate, we concur that the rate expressed as mg/min depends on total catalyst\nloading rather than intrinsic activity. Therefore, we have replaced the depolymerization rate in the\noriginal Fig. 3b with the plastic conversion, as suggested by the reviewer, and redrawn the conversion-\nselectivity-STY relationship diagram (Response Fig. 5). This figure presents the polymer conversion,\nlight olefin selectivity, and light olefin STY of all catalysts, thereby more accurately reflecting their intrinsic\ncatalytic performance.\nFor the specific reaction temperature, we concur that the STY value serves only as a crude indicator of\nrelative activity, and the high STY value of the catalyst in this manuscript is partly attributable to the\nreaction temperature (500 °C). Accordingly, we have thoroughly re-evaluated all references cited for the\nperformance comparison within the manuscript. Given our reaction temperature, we have excluded\nreferences conducted below 400 °C (including Ref. 25) to ensure the validity of performance comparisons\n(Response Fig. 5 and Table 3).\n-19-\nResponse Fig. 5. Comparison of the performance of different depolymerization and recycling\ntechnologies, including the conversion of plastic, the selectivity of light olefins, and the space-time yield\nof light olefins4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16.\n-20-\nResponse Table 3. Comparison of polyolefin plastic recycling methods in the literature, including the conversion of plastic, the selectivity\nof light olefins, and the space-time yield of light olefins\nCarrier\ngas\nMass of Mass of and Reaction Reaction Reaction Space-time\nPolyolefin Types of Conversion Selectivity\nMethod polyolefin catalyst flow temperature pressure time yield (mmol\nplastics catalysts (%) (%)\nplastics (mg) (mg) rate (℃) (bar) (min) g \\minus1 h\\minus1)\ncat\n(mL\nmin\\minus1)\nHZSM-5\nHUSY\nCatalytic N\npyrolysis4 50\nSAHA\nAl MCM-41\nCatalytic\ncracking Waste N\n2\n667\\minus4000 FCC-ECAT 4000 430\\minus527 1 900 26.7\\minus45.2 4.3\\minus9.5 0.06\\minus1.43\n(mixed gas PP/HDPE 30\noil/wax)5\nCatalytic N\ncracking6 300\nCatalytic Waste N\n2\n75\\minus90 E-Cat 250\\minus300 450\\minus460 1 30 85.0\\minus95.0 3.20\\minus28.2 0.46\\minus2.89\ncracking7, 8 PP/PE 600\nCatalytic N\npyrolysis9 700\nCatalytic N\ncracking10 12000\n-21-\nCatalytic N\npyrolysis11 400\nZSM-5\nE-Cat\nE-\nCatalytic\nPP/PE 0.4 Cat+ZSM-5 16\\minus60 / 600 1 100 75.0\\minus90.0 13.3\\minus24.2 0.05\\minus0.08\npyrolysis12\nE-\nCat+HZSM-\nTandem PE/ Ar\ncracking13 Oligomer 40\nCat-2\nLSP-Z100\nTandem N\ncracking14 10\nP-HZSM-5\nH-ZSM-5\nRapid joule He\nPE/PP 10\\minus12 Carbon 967.6 540\\minus750 1 1 90.0 45.0\\minus74.0 9.08\\minus15.0\nheating15 25\nfibre paper\nElectrified\nGraphite\nspatiotemporal PP 100\\minus1000 / Ar 600 1 35 100.0 35.5 6.28\\minus9.57\nfelt\nheating16\nWaste N\nPP/PE 4\n-22-\nWe have revised the relevant description in Section 2.2 of the manuscript (Page 9, Line 179\\minus182):\nStrikingly, when benchmarked against state-of-the-art catalysts, the GaInNiSn LAC is far ahead in terms\nof the STY and monomer selectivity (Fig. 3b and Table S6), especially in STY, which is an order of magnitude\ngreater than the current record holder15.\nWe have revised the relevant description in Section 2.2 of the manuscript (Page 9, Line 198\\minus201):\nThe depolymerization of a six-component blend, comprising equal masses of the above pure polyolefins,\nproduced light olefins with selectivity of 74.9% and a STY of 143.4 mmol g \\minus1 h\\minus1, still remarkably\ncat\noutperforming other technologies (Fig. 3b).\nWe have revised the relevant description in the Methods section (Page 13, Line 291\\minus305) of the\nmanuscript:\nAs illustrated in Fig. S16b, a piece of quartz wool (0.23 g) was placed in a quartz tube with an inner\ndiameter of 16 mm. Specifically, the quartz wool is used to hold the LAC and facilitates uniform gas flow\nthrough the reactor; this approach is consistent with standard experimental protocols reported in the\nliterature1, 2. The LAC used in the depolymerization experiments (including GaIn, GaInSn, GaInNi, and\nGaInNiSn) all weighed 1.95 g. Unlike supported catalysts, the LAC formed a liquid layer (diameter 1.6 cm,\nheight 0.15 cm) within the reactor (Fig. S16c) and thus did not undergo agglomeration during heating.\nMoreover, the molten LAC cannot permeate into the quartz wool owing to its high surface tension (> 500\nmN m\\minus1). The micrometre-scale voids formed by the interwoven quartz wool form a capillary structure.\nFor non-wetting interfaces, capillary forces act as repulsive forces, thereby impeding the penetration of\nthe LAC into the quartz wool3.\nWe have revised the relevant description in the Methods section (Page 15, Line 334\\minus342) of the\nmanuscript:\nThe conversion of plastic, the selectivity of light olefins, and the STY of light olefins were calculated using\nthe following equations:\n-23-\n-24-\nC o n v e r s io n =\n\\left(\\begin{array}{c} M\nR ea cto r,0\nM\nP\n-\\la\nM\nstic\nR ea cto r,t\n\\end{array}\\right)\n\\times 1 0 0 % (1)\nS e le c t iv it y =\n\\sum\nX\nin\nX\n1 i\n\\times 1 0 0 % (2)\nS T Y =\n\\sum M n\nLig h t o lefin\n\\times\nLiq u id a llo y\ns\nt\n(3)\nwhere M denotes the mass of the reactor before reaction (comprising the quartz tube, quartz wool,\nReactor,0\nliquid alloy catalyst, and plastic), M denotes the mass of the reactor after reaction, and M\nReactor,t Plastic\ndenotes the mass of plastic added to the reactor before reaction; X denotes the molar fraction of gas\ni\nproduct i (including H , CH , C H , C H , C H , C H , C H , and C H ), and n is the number of gas products;\n2 4 2 4 2 6 3 6 3 8 4 8 4 10\n\\sum n is the amount of light olefins (including C H , C H , and C H ) in millimoles, M is the\nLight olefins 2 4 3 6 4 8 Liquid alloy\nmass of the LAC in grams, and t is the reaction time in hours.\nWe have updated Fig. 3 in the manuscript and Table S6 in the supporting information:\nFig. 3. Depolymerization performance of the GaInNiSn MELAC. (a) Comparison of depolymerization\nperformance between ternary and quaternary liquid alloy catalysts (all active metals being Ni). The\ndashed line denotes the average STY of the ternary LACs (105.35 mmol g \\minus1 h\\minus1). Reaction conditions:\ncat\n1.0 g of polypropylene plastic, 1.95 g of different LACs (SnBiNi, InBiNi, InSnNi, GaBiNi, GaSnNi, GaInNi,\nand GaInNiSn), N feed gas at a flow rate of 4 mL min\\text{--}1, and 500 °C for 3 min. (b) Comparison of the\n2\nperformance of different depolymerization and recycling technologies, including the conversion of plastic,\nthe selectivity of light olefins, and the space-time yield of light olefins4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16. (c) Space-\n-25-\ntime yield of light olefins and selectivity of gaseous products during depolymerization of diverse polyolefin\nplastics. Reaction conditions: 1.0 g of reactants (PP, LDPE, HDPE, PS, POE, and SBS), 1.95 g of GaInNiSn\nMELAC, N feed gas at a flow rate of 4 mL min\\text{--}1, and 500 °C for 3 min. PP+LDPE, PP+HDPE, PP+PS, PP+POE,\n2\nand PP+SBS, respectively, denote equal mass ratio binary blends of PP and the corresponding polymer.\nMix denotes the equal mass ratio mixture of these six reactants. (d) Space-time yield of light olefins and\nselectivity of gaseous products during depolymerization of real-world plastic waste. Reaction conditions:\n1.0 g of reactants (food packaging bags, take-away containers, drinking water bottle caps, milk bottles,\nbeverage straws, toothpaste tubes, foam boxes, reagent buckets, and medical ziplock bags), 1.95 g of\nGaInNiSn MELAC, N feed gas at a flow rate of 4 mL min\\text{--}1, and 500 °C for 3 min. Mix denotes the equal\n2\nmass ratio mixture of these nine reactants.\n-26-\nTable S6. Comparison of polyolefin plastic recycling methods in the literature, including the conversion of plastic, the selectivity of light\nolefins, and the space-time yield of light olefins\nCarrier\ngas\nMass of Mass of and Reaction Reaction Reaction Space-time\nPolyolefin Types of Conversion Selectivity\nMethod polyolefin catalyst flow temperature pressure time yield (mmol\nplastics catalysts (%) (%)\nplastics (mg) (mg) rate (℃) (bar) (min) g \\minus1 h\\minus1)\ncat\n(mL\nmin\\minus1)\nHZSM-5\nHUSY\nCatalytic N\npyrolysis4 50\nSAHA\nAl MCM-41\nCatalytic\ncracking Waste N\n2\n667\\minus4000 FCC-ECAT 4000 430\\minus527 1 900 26.7\\minus45.2 4.3\\minus9.5 0.06\\minus1.43\n(mixed gas PP/HDPE 30\noil/wax)5\nCatalytic N\ncracking6 300\nCatalytic Waste N\n2\n75\\minus90 E-Cat 250\\minus300 450\\minus460 1 30 85.0\\minus95.0 3.20\\minus28.2 0.46\\minus2.89\ncracking7, 8 PP/PE 600\nCatalytic N\npyrolysis9 700\nCatalytic N\ncracking10 12000\n-27-\nCatalytic N\npyrolysis11 400\nZSM-5\nE-Cat\nE-\nCatalytic\nPP/PE 0.4 Cat+ZSM-5 16\\minus60 / 600 1 100 75.0\\minus90.0 13.3\\minus24.2 0.05\\minus0.08\npyrolysis12\nE-\nCat+HZSM-\nTandem PE/ Ar\ncracking13 Oligomer 40\nCat-2\nLSP-Z100\nTandem N\ncracking14 10\nP-HZSM-5\nH-ZSM-5\nRapid joule He\nPE/PP 10\\minus12 Carbon 967.6 540\\minus750 1 1 90.0 45.0\\minus74.0 9.08\\minus15.0\nheating15 25\nfibre paper\nElectrified\nGraphite\nspatiotemporal PP 100\\minus1000 / Ar 600 1 35 100.0 35.5 6.28\\minus9.57\nfelt\nheating16\nWaste N\nPP/PE 4\nACTION: Manuscript and Supporting Information amended\n-28-\n4. The outdoor photovoltaics-driven depolymerization system is inadequately described. No\nindication is given of the type of reactor is used, how the polymer is fed to the reactor, and how\nlong the polymer is heated and to what temperature. This is unacceptable. It is suggested that the\nauthors should either leave out this part of the text in this manuscript and present a more thorough\ndescription in a separate manuscript. With significantly more information, the critical reader is left\nwith too many unanswered questions. The same is true for the techno-economic analysis. The\nreliability of such analyses hinges on many assumptions, and the evidence supporting them. This\npart of the text is too short to judge whether the authors projections for the economic viability of\ntheir process are realistic.\n4.1. The outdoor photovoltaics-driven depolymerization system is inadequately described. No\nindication is given of the type of reactor is used, how the polymer is fed to the reactor, and how\nlong the polymer is heated and to what temperature. This is unacceptable. It is suggested that the\nauthors should either leave out this part of the text in this manuscript and present a more thorough\ndescription in a separate manuscript. With significantly more information, the critical reader is left\nwith too many unanswered questions.\nResponse: We genuinely thank you for your constructive suggestions and deeply apologise for the\ninadequate description of the outdoor photovoltaics-driven depolymerization system. Taking into\naccount Comment 4 from Reviewer #3, we have supplemented the information on the outdoor system\n(including reactor type, how the polymer is fed to the reactor, reaction time, reaction temperature,\nexperimental dates, and the quantities of plastic and catalysts added).\nThe outdoor photovoltaics-driven depolymerization system built in this study consisted of two\ncomponents: a solar power system and a waste plastic depolymerization system. The solar power system\nused four TY-450M photovoltaic panels (2278 × 1134 × 30 mm) with an irradiation area of 10.3 m2\n(module efficiency of 24%). Additionally, four 12 V\\text{--}200 Ah storage batteries (storage capacity of 9.6 kWh)\nwere equipped to store photovoltaic power, which is then converted by inverters for use in\ndepolymerization reactions. Meanwhile, the batteries also stabilise power output and balance the effects\nof variations in weather and sunlight intensity. The reactor used in the outdoor photovoltaics-driven\ndepolymerization system is shown in Response Fig. 6a, comprising a vacuum heat pipe reactor and a\n-29-\ncontinuous feed apparatus. The vacuum heat pipe reactor comprised an outer pipe of 300 mm in length\nand 32 mm in diameter, an inner pipe of 450 mm in length and 20 mm in diameter, and a vacuum layer\nof 300 mm in length and 3 mm in thickness. The vacuum heat pipe reactor was fixed using an aluminium\nbracket (dimensions: 330 × 350 × 650 mm). We used the customised continuous feed apparatus\n(Response Fig. 6b) to feed the polymer into the reactor. Post-consumer plastic product fragments (e.g.,\nfood packaging bags, take-away containers, drinking water bottle caps, milk bottles, beverage straws,\ntoothpaste tubes, foam boxes, reagent buckets, and medical ziplock bags) were loaded into the\ncontinuous feed apparatus and conveyed to the reactor via a screw rod at the left end of the apparatus.\nThe continuous feed apparatus delivered plastic fragments into the inner tube at a feed rate of 2.92 g\nmin\\text{--}1. For the production of light olefins (C H , C H , and C H ), 11.7 g of the GaInNiSn MELAC was used.\n2 4 3 6 4 8\nThe GaInNiSn MELAC was placed into the reactor only before the commencement of the reaction and was\nneither added nor removed during continuous operation. The outdoor system was constructed on the\nroof of the experimental building and operated continuously for over 120 hours between July 6th and July\n20th, 2025 (daily from 8:30 to 16:30), with a reaction temperature of 500 °C and an ambient temperature\nranging from 22.3 to 28.1 °C. The generated light olefins were collected in aluminium foil gas sampling\nbags, and their detailed composition and corresponding percentages were determined via GC-MS\nanalysis (off-line mode).\n-30-\nResponse Fig. 6. (a) Quartz tube reactor for the outdoor photovoltaics-driven depolymerization system.\n(b) Continuous feed apparatus.\nWe have updated Section 2.3 of the manuscript (Page 11, Line 233\\minus250):\nTo assess the scalability of this process for practical implementation, we constructed an outdoor\nphotovoltaics-driven depolymerization system in Dalian City, Liaoning Province, China. As illustrated in\nFig. 5a, the system comprises four photovoltaic panels (irradiation area of 10.3 m2, module efficiency of\n24%), an electromagnetic induction heating apparatus (operating power 380 Wh), a vacuum heat pipe\nreactor, and four storage batteries with a combined capacity of 9.6 kWh. This system was loaded with\n11.7 g of the GaInNiSn MELAC to recycle real-world polyolefin waste, consistent with the blends tested in\nSection 2.2. The real-world waste fragments were conveyed into the reactor via a continuous feed\napparatus at a feed rate of 2.92 g min\\text{--}1 (Fig. S28). The process flow and unit schematics of the system\n-31-\nare provided in Fig. 5b, with further details in the Methods section. The outdoor system operated\ncontinuously for 120 hours from 6th July to 20th July 2025 (daily from 08:30 to 16:30). Ambient\ntemperatures during operation ranged from 22.3 to 28.1 °C, with outdoor solar irradiance recorded in\nFig. S29a. Despite fluctuations in photovoltaic output, the energy supply to the reaction apparatus\nremained stable due to the battery buffer (Fig. S29b). As shown in Fig. 5c, the system achieved a light\nolefin production rate of 52.8 L h\\text{--}1 and selectivity of 71.5% (Table S9), summing up 6337 L light olefins\nover 120 hours and thus suggesting excellent operational stability. The energy consumption of the\ndepolymerization process by our system was calculated to be 3.8 kWh kg \\text{--}1. Notably, compared\nLight olefins\nwith other depolymerization technologies (Fig. 5d), our system offers over five times higher production\nrates and ten times longer stability, highlighting its significant advantages10.\nWe have updated the Methods section of the manuscript (Page 16, Line 345\\minus371):\nThe outdoor photovoltaics-driven depolymerization system built in this study consisted of two\ncomponents: a solar power system and a waste plastic depolymerization system. The solar power system\nused four TY-450M photovoltaic panels (2278 × 1134 × 30 mm) with an irradiation area of 10.3 m2\n(module efficiency of 24%). Additionally, four 12 V\\text{--}200 Ah storage batteries (storage capacity of 9.6 kWh)\nwere equipped to store photovoltaic power, which is then converted by inverters for use in\ndepolymerization reactions. Meanwhile, the batteries also stabilise power output and balance the effects\nof variations in weather and sunlight intensity. The waste plastic depolymerization system used a\ncustomised vacuum heat pipe reactor, which comprised an outer pipe of 300 mm in length and 32 mm in\ndiameter, an inner pipe of 450 mm in length and 20 mm in diameter, and a vacuum layer of 300 mm in\nlength and 3 mm in thickness (Fig. S28a). The vacuum heat pipe reactor was fixed using an aluminium\nbracket (dimensions: 330 × 350 × 650 mm). Subsequently, post-consumer plastic product fragments (e.g.,\nfood packaging bags, take-away containers, drinking water bottle caps, milk bottles, beverage straws,\ntoothpaste tubes, foam boxes, reagent buckets, and medical ziplock bags) were loaded into the\ncontinuous feed apparatus and conveyed to the reactor via a screw rod at the left end of the apparatus\n(Fig. S28b). The continuous feed apparatus delivered plastic fragments into the inner tube at a feed rate\nof 2.92 g min\\text{--}1. For the production of light olefins (C H , C H , and C H ), 11.7 g of the GaInNiSn MELAC\n2 4 3 6 4 8\nwas used. The GaInNiSn MELAC was placed into the reactor only before the commencement of the\n-32-\nreaction and was neither added nor removed during continuous operation. The induction heating\napparatus was a JRHG-3 KW UHF ultra-high frequency induction heating apparatus (maximum output\npower: 3 kW; working frequency: 500\\text{--}1100 kHz) supplied by Jinrui Intelligent Technology Co., Ltd.\n(Dongguan, Guangdong Province, China). The outdoor system was constructed on the roof of the\nexperimental building and operated continuously for over 120 hours between July 6th and July 20th, 2025\n(daily from 8:30 to 16:30), with a reaction temperature of 500 °C and an ambient temperature ranging\nfrom 22.3 to 28.1 °C (Fig. S29). The generated light olefins were collected in aluminium foil gas sampling\nbags, and their detailed composition and corresponding percentages were determined via GC-MS\nanalysis (off-line mode).\nFig. S28. (a) Quartz tube reactor for the outdoor photovoltaics-driven depolymerization system. (b)\nContinuous feed apparatus.\n-33-\nACTION: Manuscript and Supporting Information amended\n4.2. The same is true for the techno-economic analysis. The reliability of such analyses hinges on many\nassumptions, and the evidence supporting them. This part of the text is too short to judge whether\nthe authors projections for the economic viability of their process are realistic.\nResponse: We appreciate the reviewer's insightful comment and sincerely apologise for the\nincompleteness of the information in the techno-economic analysis. Indeed, such analyses hinge on\nnumerous assumptions and the evidence supporting them, yet this manuscript is limited by length\nconstraints and does not allow for exhaustive discussion and analysis. Consequently, we fully concur with\nthe reviewer's suggestion and have removed all content related to the techno-economic analysis from\nboth the manuscript and supporting information.\nTo this end, we have removed the content concerning the techno-economic analysis from Section 2.3 of\nthe manuscript, along with Fig. 5e\\text{--}f. Furthermore, we have removed Supplementary Note 3 and Tables\nS11\\text{--}S17 from the supporting information.\nWe have also updated the relevant description in the Abstract of the manuscript (Page 2, Line 24\\text{--}25):\nFurthermore, an outdoor photovoltaics-driven polyolefin waste depolymerization system was\nconstructed, maintaining a light olefin output of 52.8 L h\\text{--}1 during 120 hours of continuous operation.\nWe have also updated the relevant description in the Introduction of the manuscript (Page 5, Line\n79\\text{--}81):\nFurthermore, we constructed an outdoor photovoltaics-driven depolymerization system for real-world\npolyolefin waste, maintaining a light olefin production rate of 52.8 L h\\text{--}1 in more than 120 hours of\ncontinuous operation.\nWe have also updated the relevant description in Conclusion (Page 12, Line 266\\text{--}268) and Fig. 5e\\text{--}g\nfrom the manuscript, along with Supplementary Note 3 and Tables S11\\text{--}S17 from the supporting\ninformation.\n-34-\nAn outdoor photovoltaics-driven depolymerization system for real-world plastic blends was constructed,\nmaintaining a light olefin production rate of 52.8 L h\\text{--}1 and selectivity of 71.5% during 120 hours of\ncontinuous operation.\nFig. 5. Outdoor photovoltaics-driven depolymerization system. (a) Images of the outdoor system for\ncontinuous operation using solar energy and its demonstration configuration. (b) Schematic diagram of\nthe technical route for closed-loop recycling of real-world plastic waste. (c) Generation rate and selectivity\nof light olefins during 120 hours of continuous operation (July 6th to July 20th, 2025; daily from 8:30 to\n16:30) using this outdoor system. Reaction conditions: real-world plastic waste fragments (including food\npackaging bags, take-away containers, drinking water bottle caps, milk bottles, beverage straws,\ntoothpaste tubes, foam boxes, reagent buckets, and medical ziplock bags) are conveyed into the reactor\nvia a continuous feed apparatus at a feed rate of 2.92 g min\\text{--}1 (Fig. S28), 11.7 g of GaInNiSn MELAC, N\n2\nfeed gas at a flow rate of 4 mL min\\text{--}1, and 500 °C for 120 hours. (d) Comparison of the performance of\ndifferent recycling technologies, including operational stability and the generation rate of light olefins4, 5,\n6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22.\nACTION: Manuscript and Supporting Information amended\n-35-\nReviewer #2:\nThe manuscript by Xu et al. presents a new depolymerization catalyst for polyolefin waste based on a\nquarternary alloy GaInNiSn. The topic of the manuscript is highly relevant and the catalyst presented in\nthe manuscript seems to work well. The catalyst was not only used at the lab scale but in a 'real-word'\nsetup. The GaInNiSn alloy is characterized very well by state-of-the-art characterization techniques:\nResponse: We sincerely thank the reviewer for the careful and insightful review of our manuscript. Your\nvaluable feedback has provided critical guidance for improving our work, and we have carefully\naddressed all the points you raised. We have supplemented key experimental details, refined data\nanalysis, and clarified core claims to enhance the clarity, rigour, and completeness of the manuscript.\n1. The manuscript in its present form, however, makes it difficult to judge whether it is suitable for\nNature Communications because crucial information is not provided. The key claim of the authors\nis that their catalyst has a distinctively higher space-time yield than competing known catalysts.\nFigure 1a shows that the GaInNiSn catalyst has a somewhat but not dramatically increased space-\ntime yield compared to the GaInNi catalyst. In so far, the improvement is more incremental.\nResponse: We appreciate the reviewers' insightful comments and sincerely apologize for the misleading\ninformation due to our formulation in the original manuscript. We should clarify that the ternary GaInNi\nis also one of the LAC catalysts we designed by our proposed S tuning strategy (Fig. 3a), instead of\nif-config\na “competing known catalyst”. The motivation to synthesize a ternary GaInNi as a control group is to\nhighlight the effectiveness of our proposed interfacial entropy tuning strategy. Strikingly, despite the\ninferior performance of GaInNi than the quaternary alloy GaInNiSn, it also significantly exceeds the\n“competing known counterparts” by seven times. To further underscore the proposed strategy in\ndesigning LAC catalysts, we synthesised other ternary LACs with an identical active metal content (10wt%\nNi): SnBiNi, InBiNi, InSnNi, GaBiNi, and GaSnNi. Subsequently, these LACs were subjected to catalytic\nperformance testing. We found that the space-time yield (STY) of light olefins of the quaternary GaInNiSn\nLAC exceeded the average STY of light olefins of the ternary LACs by 75.4% and outperformed the state-\nof-the-art catalyst by at least one order of magnitude (Fig. 3b). These results demonstrates that the\nincrease in interfacial configurational entropy (S ) induces a significant improvement in the STY of\nif-config\n-36-\nlight olefins.\nSpecifically, the STY of light olefins during the depolymerization of polypropylene plastic using ternary\nLACs ranged from 94.5 to 123.3 mmol g \\minus1 h\\minus1. In comparison, the STY of the quaternary GaInNiSn LAC\ncat\nreached 181.5 mmol g \\minus1 h\\minus1, representing a 75.4% increase over the average STY of the ternary LACs\ncat\n(Response Fig. 7) and at least one order of magnitude over the state-of-the-art catalysts. Moreover, the\nS of ternary LACs ranged between 4.92 and 5.88 J mol\\minus1 K\\minus1, while the S of the quaternary\nif-config if-config\nGaInNiSn LAC reached 8.55 J mol\\minus1 K\\minus1, representing a 60.4% increase over the average S of the\nif-config\nternary LACs (Response Table 4). The above results imply that as the S increases, the improvement\nif-config\nin STY of quaternary GaInNiSn LAC is significant instead of incremental. It is due to the fact that\nintroducing multiple elements into a dominant liquid metal significantly increases its interface disorder\nand thus enhances the S of LACs, reducing interfacial free energy and driving the interfacial\nif-config\nenrichment of active sites. Strikingly, although the S of the quaternary LAC shows a slight increase\nif-config\nin comparison with ternary LACs, the quaternary GaInNiSn LAC yields an average improvement in the\ndepolymerization performance in terms of STY of light olefins, demonstrating the effectiveness of this S\nif-\ntuning strategy.\nconfig\nResponse Fig. 7. (a) Comparison of depolymerization performance between ternary and quaternary\nliquid alloy catalysts (all active metals being Ni). The dashed line denotes the average STY of the ternary\nLACs (103.45 mmol g \\minus1 h\\minus1). Reaction conditions: 1.00 g of polypropylene plastic, 1.95 g of different\ncat\nLACs (SnBiNi, InBiNi, InSnNi, GaBiNi, GaSnNi, GaInNi, and GaInNiSn), N feed gas at a flow rate of 4 mL\n2\nmin\\text{--}1, and 500 °C for 3 min. (b) Comparison of the performance of different depolymerization and\nrecycling technologies, including the conversion of plastic, the selectivity of light olefins, and the space-\n-37-\ntime yield of light olefins4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16.\nResponse Table 4. Comparison of the S of liquid alloys in this work\nif-config\nSample Element x (mol%) S (J mol\\minus1 K\\minus1) Evaluation\ni if-config\nSn 79.14\nSnBiNi Bi 18.25 4.92 Low entropy\nNi 2.61\nIn 80.51\nInBiNi Bi 15.32 4.94 Low entropy\nNi 4.17\nIn 75.35\nInSnNi Sn 20.08 5.61 Low entropy\nNi 4.57\nGa 77.88\nGaBiNi Bi 18.74 5.16 Low entropy\nNi 3.38\nGa 76.96\nGaSnNi Sn 18.21 5.45 Low entropy\nNi 4.83\nGa 61.43\nGaInNi In 38.71 5.88 Low entropy\nNi 0.86\nGa 62.52\nIn 20.90\nGaInNiSn 8.55 Medium entropy\nNi 8.74\nSn 7.84\nThe data used for calculating the S of the alloys (SnBiNi, InBiNi, InSnNi, GaBiNi, GaSnNi, GaInNi, and\nif-config\nGaInNiSn) were all derived from XPS spectra. The alloys were synthesised with well-defined mass ratios:\nSnBiNi (Sn:Bi:Ni = 6:3:1), InBiNi (In:Bi:Ni = 6:3:1), InSnNi (In:Sn:Ni = 6:3:1), GaBiNi (Ga:Bi:Ni = 6:3:1),\nGaSnNi (Ga:Sn:Ni = 6:3:1), GaInNi (Ga:In:Ni = 6:3:1), and GaInNiSn (Ga:In:Ni:Sn = 60:30:6:4).\n-38-\nWe have updated Section 2.2 and Fig. 3a in the manuscript:\nAs shown in Fig. 3a, although the S of the quaternary LAC shows a modest increase in comparison\nif-config\nwith ternary LACs, the quaternary GaInNiSn LAC yields a substantial improvement of 75.4% in the\ndepolymerization performance in terms of STY of light olefins, highlighting the effectiveness of this S\nif-\ntuning strategy. Strikingly, when benchmarked against state-of-the-art catalysts, the GaInNiSn LAC\nconfig\nis far ahead in terms of the STY and monomer selectivity (Fig. 3b and Table S6), especially in STY, which\nis an order of magnitude greater than the current record holder24.\n-39-\nFig. 3. Depolymerization performance of the GaInNiSn MELAC. (a) Comparison of depolymerization\nperformance between ternary and quaternary liquid alloy catalysts (all active metals being Ni). The\ndashed line denotes the average STY of the ternary LACs (103.45 mmol g \\minus1 h\\minus1). Reaction conditions:\ncat\n1.00 g of polypropylene plastic, 1.95 g of different LACs (SnBiNi, InBiNi, InSnNi, GaBiNi, GaSnNi, GaInNi,\nand GaInNiSn), N feed gas at a flow rate of 4 mL min\\text{--}1, and 500 °C for 3 min. (b) Comparison of the\n2\nperformance of different depolymerization and recycling technologies, including the conversion of plastic,\nthe selectivity of light olefins, and the space-time yield of light olefins4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16. (c) Space-\n-40-\ntime yield of light olefins and selectivity of gaseous products during depolymerization of diverse polyolefin\nplastics. Reaction conditions: 1.00 g of reactants (PP, LDPE, HDPE, PS, POE, and SBS), 1.95 g of GaInNiSn\nMELAC, N feed gas at a flow rate of 4 mL min\\text{--}1, and 500 °C for 3 min. PP+LDPE, PP+HDPE, PP+PS, PP+POE,\n2\nand PP+SBS, respectively, denote equal mass ratio binary blends of PP and the corresponding polymer.\nMix denotes the equal mass ratio mixture of these six reactants. (d) Space-time yield of light olefins and\nselectivity of gaseous products during depolymerization of real-world plastic waste. Reaction conditions:\n1.00 g of reactants (food packaging bags, take-away containers, drinking water bottle caps, milk bottles,\nbeverage straws, toothpaste tubes, foam boxes, reagent buckets, and medical ziplock bags), 1.95 g of\nGaInNiSn MELAC, N feed gas at a flow rate of 4 mL min\\text{--}1, and 500 °C for 3 min. Mix denotes the equal\n2\nmass ratio mixture of these nine reactants\nWe have updated the Supplementary Note 2 and Table S1 in the supporting information:\nTo compare the catalytic performance of ternary liquid alloy catalysts (LACs) with our designed\nquaternary GaInNiSn LAC, we synthesised other ternary LACs with an identical active metal content (10wt%\nNi): SnBiNi, InBiNi, InSnNi, GaBiNi, and GaSnNi. Subsequently, these LACs were subjected to\ncharacterisation and catalytic performance testing. We found that the space-time yield (STY) of light\nolefins of the quaternary GaInNiSn LAC exceeded the average STY of light olefins of the ternary LACs by\n75.4% and outperformed the state-of-the-art catalyst by at least one order of magnitude. This result\ndemonstrates that the increase in interfacial configurational entropy (S ) induces a significant\nif-config\nimprovement in the STY of light olefins.\nSpecifically, the STY of light olefins during the depolymerization of polypropylene plastic using ternary\nLACs ranged from 94.5 to 123.3 mmol g \\minus1 h\\minus1. In comparison, the STY of the quaternary GaInNiSn LAC\ncat\nreached 181.5 mmol g \\minus1 h\\minus1, representing a 75.4% increase over the average STY of the ternary LACs\ncat\n(Response Fig. 7). Moreover, the S of ternary LACs ranged between 4.92 and 5.88 J mol\\minus1 K\\minus1, while\nif-config\nthe S of the quaternary GaInNiSn LAC reached 8.55 J mol\\minus1 K\\minus1, representing a 60.4% increase over\nif-config\nthe average S of the ternary LACs (Response Table 4). The above results imply that as the S\nif-config if-config\nincreases, the improvement in STY of quaternary GaInNiSn LAC is significant instead of incremental. It is\ndue to the fact that introducing multiple elements into a dominant liquid metal significantly increases its\ninterface disorder and thus enhances the S of LACs, reducing interfacial free energy and driving the\nif-config\n-41-\ninterfacial enrichment of active sites. Strikingly, although the S of the quaternary LAC shows a slight\nif-config\nincrease in comparison with ternary LACs, the quaternary GaInNiSn LAC yields an average improvement\nin the depolymerization performance in terms of STY of light olefins, demonstrating the effectiveness of\nthis S tuning strategy.\nif-config\nTable S1. Comparison of the S of liquid alloys between this work and previous literature\nif-config\nSample Element x (mol%) S (J mol\\minus1 K\\minus1) Evaluation\ni if-config\nGaNi Ga 99.43\n0.29 Low entropy\n(This work) Ni 0.57\nGa 99.41\nGaSn23 0.30 Low entropy\nSn 0.59\nGa 98.93\nGaZn23 0.49 Low entropy\nZn 1.07\nGa 98.58\nGaMg23 0.62 Low entropy\nMg 1.42\nGa 97.81\nGaCu24, 25 0.87 Low entropy\nCu 2.19\nInNi In 93.91\n1.91 Low entropy\n(This work) Ni 6.09\nGa 92.60\nGaAl23 2.20 Low entropy\nAl 7.40\nSnNi Sn 87.38\n3.25 Low entropy\n(This work) Ni 12.62\nGa 83.54\nEGaIn26, 27, 28 3.71 Low entropy\nIn 16.46\nPb 83.00\nPbNi29 3.79 Low entropy\nNi 17.00\nGaIn Ga 76.70\n4.51 Low entropy\n(This work) In 23.30\nBi 73.00\nBiNi1, 29 4.86 Low entropy\nNi 27.00\nSn 89.86\nSnInCu30 2.97 Low entropy\nIn 9.29\n-42-\nCu 0.85\nBi 89.75\nBiNiMo1 Ni 7.63 3.23 Low entropy\nMo 2.62\nSn 79.14\nSnBiNi\nBi 18.25 4.92 Low entropy\n(This work)\nNi 2.61\nIn 80.51\nInBiNi\nBi 15.32 4.94 Low entropy\n(This work)\nNi 4.17\nGa 77.90\nGaSnCu25 Sn 19.61 5.03 Low entropy\nCu 2.49\nGa 77.39\nGaInCu25 In 20.13 5.11 Low entropy\nCu 2.48\nGa 77.88\nGaBiNi\nBi 18.74 5.16 Low entropy\n(This work)\nNi 3.38\nGa 78.36\nEGaInSn25, 26, 28 In 14.93 5.40 Low entropy\nSn 6.72\nGa 76.96\nGaSnNi\nSn 18.21 5.45 Low entropy\n(This work)\nNi 4.83\nGa 61.43\nGaInNi\nIn 38.71 5.88 Low entropy\n(This work)\nNi 0.86\nIn 75.35\nInSnNi\nSn 20.08 5.61 Low entropy\n(This work)\nNi 4.57\nGaInSn Ga 71.35 6.31 Low entropy\n-43-\n(This work)\nIn 21.67\nSn 6.98\nGa 62.52\nIn 20.90\nGaInNiSn\n8.55 Medium entropy\n(This work, 25 °C)\nNi 8.74\nSn 7.84\nGa 55.68\nIn 20.14\nGaInNiSn\n9.62 Medium entropy\n(This work, 500 °C)\nNi 12.75\nSn 11.43\nThe data used for calculating the S of the alloys (GaNi, InNi, SnNi, SnBiNi, InBiNi, GaBiNi, GaSnNi,\nif-config\nGaInNi, InSnNi, and GaInNiSn) were all derived from XPS spectra. The alloys were synthesized with well-\ndefined mass ratios: GaNi (Ga:Ni = 9:1), InNi (In:Ni = 9:1), SnNi (Sn:Ni = 9:1), SnBiNi (Sn:Bi:Ni = 6:3:1),\nInBiNi (In:Bi:Ni = 6:3:1), GaBiNi (Ga:Bi:Ni = 6:3:1), GaSnNi (Ga:Sn:Ni = 6:3:1), GaInNi (Ga:In:Ni = 6:3:1),\nInSnNi (In:Sn:Ni = 6:3:1), and GaInNiSn (Ga:In:Ni:Sn = 60:30:6:4).\nACTION: Manuscript and Supporting Information amended\n2. A crucial shortcoming of the manuscript is that the catalyst setup is not really described. The\nGaInNiSn alloy is liquid at reaction temperatures. Is the liquid alloy used on some sort of support. If\nyes, what support is used and in what form the liquid alloy is on the support, droplets of a certain\nsize or otherwise? How does the actual reaction setup looks like? How is the space-time yield\ncalculated? With respect only to the amount of liquid alloy? This would be misleading, the complete\ncatalyst including support needs to be considered.\n2.1. A crucial shortcoming of the manuscript is that the catalyst setup is not really described. The\nGaInNiSn alloy is liquid at reaction temperatures. Is the liquid alloy used on some sort of support. If\nyes, what support is used and in what form the liquid alloy is on the support, droplets of a certain\nsize or otherwise? How does the actual reaction setup looks like?\nResponse: We are grateful to the reviewers for pointing out critical omissions in the description of the\n-44-\ncatalyst setup. These omissions have indeed affected the clarity of our work, and we sincerely apologise\nfor this oversight.\nThe indoor experimental setup is depicted in Response Fig. 8, comprising a depolymerization reactor, a\nlaser thermo-detector, a laser thermo-detector control box, an induction heating apparatus, and a gas\nchromatograph. As illustrated in Response Fig. 9b, the aluminosilicate refractory fibres are used to hold\nthe liquid alloy catalyst and facilitate uniform gas flow through the reactor, and this approach is\nconsistent with standard experimental protocols reported in the literature1, 2. Unlike supported catalysts,\nthe GaInNiSn MELAC remains liquid at room temperature and forms a liquid layer (diameter 1.6 cm,\nheight 0.15 cm) within the reactor (Response Fig. 9c). Moreover, the LAC cannot permeate into the quartz\nwool owing to its high surface tension (> 500 mN m\\minus1). The micrometre-scale voids formed by the\ninterwoven quartz wool form a capillary structure. For non-wetting interfaces, capillary forces act as\nrepulsive forces, thereby impeding the penetration of the LAC into the quartz wool3. Furthermore, the\npolymer was placed above the LAC and thus did not make direct contact with the quartz wool in\ndepolymerization processing (Response Fig. 9b). As the density of the polymer is lower than that of the\nliquid alloy catalyst, the polymer cannot pass through the liquid alloy catalyst.\nResponse Fig. 8. Indoor experimental setup, comprising a depolymerization reactor, a laser thermo-\ndetector, a laser thermo-detector control box, an induction heating apparatus, and a gas chromatograph.\n-45-\nResponse Fig. 9. Depolymerization reactor setup. (a) Gas flow: nitrogen gas flow (orange) and gaseous\nproduct stream (blue). (b) Localised magnification of the depolymerization reaction zone in side view,\ncomprising polypropylene plastic, liquid alloy catalyst, and quartz wool. The quartz wool (0.23 g, 0.76 cm)\nis used to support the liquid alloy catalyst (1.95 g, 0.15 cm). The polypropylene plastic (1.00 g) is placed\non top of the liquid alloy, with a stacking height of 1.10 cm. (c) Localised magnification of the liquid alloy\ncatalyst from top view.\nTo clarify these details, we have rewritten the Methods section of the manuscript and revised Figs.\nS15,S16 in the supporting information. Moreover, to avoid ambiguity, all instances of “aluminosilicate\nrefractory fibre” in both the manuscript and the supporting information have been replaced with “quartz\n-46-\nwool”.\nWe have updated the Methods section of the manuscript (Page 13, Line 288\\minus302 and Line 313\\minus331):\nThe indoor experimental setup is depicted in Fig. S15, comprising a depolymerization reactor, a laser\nthermo-detector, a thermo-detector control box, an induction heating apparatus (Ambrell EASYHEAT\n0224, operating at a frequency of 150\\text{--}400 kHz, with a maximum output of 2.4 kW), and a gas\nchromatograph. As illustrated in Fig. S16, a piece of quartz wool (0.23 g) was placed in a quartz tube with\nan inner diameter of 16 mm. Specifically, the quartz wool is used to hold the LAC and facilitates uniform gas flow\nthrough the reactor; this approach is consistent with standard experimental protocols reported\n-47-\nin the literature1, 2. The LAC used in the depolymerization experiments (including GaIn, GaInSn, GaInNi,\nand GaInNiSn) all weighed 1.95 g. Unlike supported catalysts, the LAC forms a liquid layer (diameter 1.6\ncm, height 0.15 cm) within the reactor (Fig. S16c) and thus does not undergo agglomeration during\nheating. Moreover, the molten LAC cannot permeate into the quartz wool owing to its high surface\ntension (> 500 mN m\\minus1). The micrometre-scale voids formed by the interwoven quartz wool form a\ncapillary structure. For non-wetting interfaces, capillary forces act as repulsive forces, thereby impeding\nthe penetration of the LAC into the quartz wool3. Furthermore, the polymer was placed above the LAC\nand thus did not make direct contact with the quartz wool in depolymerization processing (Fig. S16b).\nFor a typical catalytic experiment, nitrogen gas was continuously purged at a flow rate of 20 mL min\\minus1\nfor 10 min to exhaust residual air. A calibrated laser thermometer (measuring wavelength 1.6 μm,\ntemperature range 250\\text{--}1200 °C) was positioned 20 cm away from the reactor to record the temperature,\nwith the output power of the induction heating apparatus adjusted in real time to achieve constant-\ntemperature heating. The cross-sectional area of the LAC can be calculated as 37.7 mm2, significantly\nlarger than the spot area of the laser thermometer (3.14 mm2). Considering the thermal conductivity of\nLAC reaches 23.7 W m\\minus1·K\\minus1, it can be thought that the overall temperature of the LAC is uniform under\nsteady state (500 °C)31. Meanwhile, through COMSOL simulations, we conducted the temperature\nevolution of the LAC during induction heating and its steady-state temperature distribution (Fig. S17).\nThe temperature distribution within the LAC was highly uniform at steady state. Consequently, we can\nmeasure the temperature of the LAC accurately by positioning the spot of the laser thermometer on the\nsurface of the LAC. Subsequently, a high-frequency electromagnetic induction unit was activated to drive\nthe LAC to depolymerize the plastics. During the 3-minute heating process of the reactor, high-purity\nnitrogen was continuously introduced as the carrier gas at a flow rate of 4 mL min\\minus1.\nAs illustrated in Fig. S15a, the nitrogen gas flowed from the bottom to the top of the quartz tube, ensuring\nthat gaseous products formed were immediately swept away by the nitrogen stream and transferred to\nthe gas collection bag, rather than remaining in continuous contact with the LAC. After the reaction\nproceeded for 3.0 min, the electromagnetic induction device was deactivated.\nWe have updated Figs. S15,S16 in the supporting information:\n-48-\nFig. S15. Indoor experimental setup, comprising a depolymerization reactor, a laser thermo-detector, a\nthermo-detector control box, an induction heating apparatus, and a gas chromatograph.\nFig. S16. Depolymerization reactor setup. (a) Gas flow: nitrogen gas flow (orange) and gaseous product\nstream (blue). (b) Localised magnification of the depolymerization reaction zone in side view, comprising\npolypropylene plastic, liquid alloy catalyst, and quartz wool. The quartz wool (0.23 g, 0.76 cm) is used to\nsupport the liquid alloy catalyst (1.95 g, 0.15 cm). The polypropylene plastic (1.00 g) is placed on top of\nthe liquid alloy, with a stacking height of 1.10 cm. (c) Localised magnification of the liquid alloy catalyst\nfrom top view.\nACTION: Manuscript and Supporting Information amended\n-49-\n2.2. How is the space-time yield calculated? With respect only to the amount of liquid alloy?\nResponse: We thank the reviewers for their constructive suggestions and apologise for the incomplete\ninformation regarding the catalyst and polymers. It should be clarified that the aluminosilicate fibre\nserves merely to hold the catalyst and facilitate uniform gas flow through the reactor, as widely used in\nlab-scale fixed-bed tests, instead of a support for the liquid metal catalyst (Response Fig. 9). The liquid\nalloy catalyst employed in the manuscript remains liquid at room temperature; the aluminosilicate fibre\nitself is not a part of the catalyst (Response Fig. 9b). Consequently, we used the total mass of the liquid\nalloy (1.95 g) without fibres in our space-time yield (STY) calculations, which was 181.5 mmol g \\minus1 h\\minus1,\ncat\nand the formula for STY is as follows:\n-50-\nS T Y =\\sum M n\nLig h t o lefin\n\\times\nLiq u id a llo y\ns\nt\n(R1)\nwhere ∑n is the amount of light olefins (including C H , C H , and C H ) in millimoles, M\nLight olefins 2 4 3 6 4 8 Liquid alloy\nis the mass of the LAC in grams, and t is the reaction time in hours.\nTo clarify these details, we have incorporated the relevant calculation formulas from the supporting\ninformation into the Methods section of the manuscript.\nWe have updated the Methods section of the manuscript (Page 13, Line 291\\minus302):\nAs illustrated in Fig. S16b, a piece of quartz wool (0.23 g) was placed in a quartz tube with an inner\ndiameter of 16 mm. Specifically, the quartz wool is used to hold the LAC and facilitates uniform gas flow\nthrough the reactor; this approach is consistent with standard experimental protocols reported in the\nliterature1, 2. The LAC used in the depolymerization experiments (including GaIn, GaInSn, GaInNi, and\nGaInNiSn) all weighed 1.95 g. Unlike supported catalysts, the LAC forms a liquid layer (diameter 1.6 cm,\nheight 0.15 cm) within the reactor (Fig. S16c) and thus does not undergo agglomeration during heating.\nMoreover, the molten LAC cannot permeate into the quartz wool owing to its high surface tension (> 500\nmN m\\minus1). The micrometre-scale voids formed by the interwoven quartz wool form a capillary structure.\nFor non-wetting interfaces, capillary forces act as repulsive forces, thereby impeding the penetration of\nthe LAC into the quartz wool3. Furthermore, the polymer was placed above the LAC and thus did not make\ndirect contact with the quartz wool in depolymerization processing (Fig. S16b).\nWe have updated the Methods section of the manuscript (Page 15, Line 334\\minus342):\nThe conversion of plastic, the selectivity of light olefins, and the STY of light olefins were calculated using\nthe following equations:\n-51-\nC o n v e r s io n =\\left(\\begin{array}{c} M\nR ea cto r,0\nM\nP\n-\\la\nM\nstic\nR ea cto r,t\n\\end{array}\\right)\n\\times 1 0 0 % (1)\nS e le c t iv it y =\\sum\nX\nin\nX\n1 i\n\\times 1 0 0 % (2)\nS T Y =\\sum M n\nLig h t o lefin\n\\times\nLiq u id a llo y\ns\nt\n(3)\nwhere M denotes the mass of the reactor before reaction (comprising the quartz tube, quartz wool,\nReactor,0\nliquid alloy catalyst, and plastic), M denotes the mass of the reactor after reaction, and M\nReactor,t Plastic\ndenotes the mass of plastic added to the reactor before reaction; X denotes the molar fraction of gas\ni\nproduct i (including H , CH , C H , C H , C H , C H , C H , and C H ), and n is the number of gas products;\n2 4 2 4 2 6 3 6 3 8 4 8 4 10\n\\sum n is the amount of light olefins (including C H , C H , and C H ) in millimoles, M is the\nLight olefins 2 4 3 6 4 8 Liquid alloy\nmass of the LAC in grams, and t is the reaction time in hours.\nACTION: Manuscript and Supporting Information amended\n3. The ab-initio MD calculation are not sufficiently describe. Is a slab model used? What unit cells are\nused with how many atoms. In the SI a figure on the ab-initio MD shows a very small number of\natoms which would be to small to draw substantial conclusions.\nResponse: We sincerely appreciate the reviewer’s feedback on the insufficient description of ab-initio\nmolecular dynamics (MD) calculations, and we apologise for the lack of critical details that cast doubt on\nthe reliability of our conclusions.\nConsidering the insufficient number of atoms in the original computational system, we have modified it\nto a 100-atom setup (matching the target compositions of GaInNi: Ga:In:Ni = 67:19:14 and GaInNiSn:\nGa:In:Ni:Sn = 69:20:8:3) and recalculated all relevant results (Response Fig. 10). Specifically, we first\ngenerated the initial atomic configurations for each alloy using PACKMOL in a 13 Å × 13 Å × 25 Å periodic\nbox to ensure precise composition control and avoid initial atomic overlap and, then, added a 15 Å\nvacuum layer along the height direction to expand the box to 13 Å × 13 Å × 40 Å (to accommodate the\nthermal mobility of liquid atoms and eliminate spurious periodic interactions between adjacent systems)\nfor performing ab-initio MD simulations (aimed at capturing the equilibrium liquid-state configurations\nof the alloys). Given our research focus on Sn-mediated Ni migration to the surface, we further extracted\nperiodic slab models (retaining the 15 Å vacuum layer to isolate surface interactions) from the\nequilibrated MD trajectories for subsequent analyses.\n-52-\nResponse Fig. 10. Time-evolving snapshots of (a) GaInNi LELAC and (b) GaInNiSn MELAC from Ab initio\nmolecular dynamics simulations.\nTo clarify these details, we have updated the Methods section of the manuscript (Page 17, Line\n372\\minus398) and Fig. S7 in the supporting information:\nConsidering that GaInNi and GaInNiSn remained in a liquid state throughout the depolymerization\n-53-\nprocess, ab initio molecular dynamics (AIMD) simulations were performed to obtain reasonable\nequilibrium configurations for both systems. Before the AIMD simulation, 100 atoms with target\ncompositions were randomly generated for each alloy using PACKMOL in a 13 Å × 13 Å × 25 Å periodic\nbox. To eliminate spurious periodic interactions between adjacent systems and accommodate the\nthermal mobility of liquid atoms, a 15 Å vacuum layer was added along the height direction of the 25 Å\nbox, resulting in a slab model of the final periodic box size of 13 Å × 13 Å × 40 Å for the formal AIMD\nsimulations. The target compositions of the two alloy systems were as follows: GaInNi (Ga:In:Ni =\n67:19:14) and GaInNiSn (Ga:In:Ni:Sn = 69:20:8:3). Notably, all these details (the number of atoms and\nthe cell dimensions) are now explicitly stated in the corresponding figure captions for the AIMD snapshots.\nFor the AIMD simulations, the plane-wave cutoff energy was set to 520 eV; a 1 × 1 × 1 k-mesh was used\nto sample the Brillouin zone, and spin-orbit coupling (SOC) was taken into account in the calculations32.\nThe samples were then equilibrated at the equilibrium temperature (773 K) for 10 ps in the canonical\nensemble (NVT). The time step was chosen to be 2 fs, and the integration of Newton’s equation was\nbased on the Verlet algorithm implemented in the Vienna Ab-initio Simulation Package (VASP).\nSubsequently, suitable atomic configurations with active sites proximal to the surface were selected from\nthe 10 ps AIMD trajectories, and periodic plane-wave density functional theory (DFT) calculations were\nperformed on GaInNi and GaInNiSn using the Vienna Ab-initio Simulation Package (VASP)33. To\ninvestigate the activation mechanism of C\\text{--}H bonds, the H adsorption energy on the active Ni sites in the\ntwo systems was calculated. The projector augmented plane wave (PAW) pseudopotential basis set and\nthe generalised gradient approximation (GGA) functional with the Perdew–Burke–Ernzerhof (PBE)\nparametrisation were employed in these calculations. A kinetic energy cutoff of 520 eV for plane-wave\nexpansion was used for the two systems. Brillouin zone sampling was performed using a 3 × 1 × 3 k-point\ngrid centred at the Γ point. The force convergence criterion was set to 0.02 eV Å\\minus1, and spin-orbit coupling\neffects were considered in the calculations. A 15 Å vacuum layer was introduced to avoid the influence\nof adjacent crystal planes on surface atoms, and the top atomic layers (surface region) were fully relaxed.\n-54-\nFig. S7. Time-evolving snapshots of (a) GaInNi LELAC and (b) GaInNiSn MELAC from Ab initio\nmolecular dynamics simulations.\nACTION: Manuscript and Supporting Information amended\n-55-\nReviewer #3:\nThis paper reports on the transformation of polyolefins into light olefins under atmospheric pressure,\nutilizing an induction heating and a quaternary GaInNiSn medium-entropy liquid alloy catalyst (MELAC).\nThrough an interfacial configurational entropy regulation strategy, the catalyst forms Ni\\delta\\minus\\text{--}Sn\\delta+ active\nsites, which facilitate C\\text{--}H bond activation and \\beta-scission. This strategy enhances the depolymerization\nperformance, achieving a high space-time yield of 181.5 mmol g \\minus1 h\\minus1 and a selectivity of 79.7% for the\ncat\ntransformation of PP into light olefins. Furthermore, the study demonstrates a photovoltaic-driven,\noutdoor continuous depolymerization system, to support its feasibility in processing real-world plastic\nwastes. The study provides a method for efficient recycling of waste polyolefin plastics, still some\nimportant issues should be resolved prior accepting the manuscript for publication:\nResponse: Thanks very much for your thoughtful comments, which help us improve the reliability and\npertinence of our manuscript. We sincerely appreciate your recognition of the extensive effort put into\nour research. We have seriously considered your comments and supplemented the related discussions.\nOur point-by-point response is as follows:\n1. Has the reaction system been temperature-corrected? How to ensure that at the fixed position of\nthe laser thermometer, the temperature at the reaction site can be accurately measured?\nResponse: We genuinely thank you for your constructive suggestions. Before the experiment, we\ncalibrated the laser thermometer using a K-type thermocouple, and the calibrated thermometer was\nemployed for subsequent experiments. Our experimental apparatus is illustrated in Response Fig. 11, the\nplastic being positioned atop the liquid alloy catalyst within a quartz tube of 16 mm internal diameter.\nThe cross-sectional area of the liquid alloy catalyst can be calculated as 37.7 mm2, significantly larger\nthan the spot area of the laser thermometer (3.14 mm2). Considering the thermal conductivity of liquid\nmetal reaches 23.7 W m\\minus1·K\\minus1, it can be thought that the overall temperature of the liquid metal is\nuniform under steady state (500 °C)31. Meanwhile, through COMSOL simulations, we conducted the\ntemperature evolution of the liquid metal during induction heating and its steady-state temperature\ndistribution (Response Fig. 12). It is evident that the temperature distribution within the liquid metal is\nhighly uniform at steady state. Consequently, we can measure the temperature of the liquid alloy catalyst\n-56-\naccurately by positioning the spot of the laser thermometer on the surface of the liquid alloy catalyst.\nResponse Fig. 11. Depolymerization reactor setup. (a) Gas flow: nitrogen gas flow (orange) and gaseous\nproduct stream (blue). (b) Localised magnification of the depolymerization reaction zone in side view,\ncomprising polypropylene plastic, liquid alloy catalyst, and quartz wool. The quartz wool (0.23 g, 0.76 cm)\nis used to support the liquid alloy catalyst (1.95 g, 0.15 cm). The polypropylene plastic (1.00 g) is placed\non top of the liquid alloy, with a stacking height of 1.10 cm. (c) Localised magnification of the liquid alloy\ncatalyst from top view.\nResponse Fig. 12. (a) Temperature variation of the liquid alloy catalyst during induction heating. (b)\ntemperature distribution of the liquid alloy catalyst via induction heating in a steady state.\n-57-\nWe have updated the Methods section (Page 13, Line 313\\minus324) of the manuscript and Figs. S16,S17 in\nthe supporting information:\nFor a typical catalytic experiment, nitrogen gas was continuously purged at a flow rate of 20 mL min\\minus1\nfor 10 min to exhaust residual air. A calibrated laser thermometer (measuring wavelength 1.6 μm,\ntemperature range 250\\text{--}1400 °C) was positioned 20 cm away from the reactor to record the LAC\ntemperature, with the output power of the induction heating apparatus adjusted in real time to achieve\nconstant-temperature heating. The cross-sectional area of the LAC can be calculated as 37.7 mm2,\nsignificantly larger than the spot area of the laser thermometer (3.14 mm2). Considering the thermal\nconductivity of LAC reaches 23.7 W m\\minus1·K\\minus1, it can be thought that the overall temperature of the LAC is\nuniform under steady state (500 °C)31. Meanwhile, through COMSOL simulations, we obtained the\ntemperature evolution of the LAC during induction heating and its steady-state temperature distribution\n(Fig. S17). The temperature distribution within the LAC is highly uniform at steady state. Consequently,\nwe can measure the temperature of the LAC accurately by positioning the spot of the laser thermometer\non the surface of the LAC.\nFig. S16. Depolymerization reactor setup. (a) Gas flow: nitrogen gas flow (orange) and gaseous product\nstream (blue). (b) Localised magnification of the depolymerization reaction zone in side view, comprising\npolypropylene plastic, liquid alloy catalyst, and quartz wool. The quartz wool (0.23 g, 0.76 cm) is used to\nsupport the liquid alloy catalyst (1.95 g, 0.15 cm). The polypropylene plastic (1.00 g) is placed on top of\n-58-\nthe liquid alloy, with a stacking height of 1.10 cm. (c) Localised magnification of the liquid alloy catalyst\nfrom top view.\nFig. S17. (a) Temperature variation of the liquid alloy catalyst during induction heating. (b) temperature\ndistribution of the liquid alloy catalyst via induction heating in a steady state.\nACTION: Manuscript and Supporting Information amended\n2. More control experiments should be conducted to make the effect of the MELAC clearer. For\nexample, the performance of control group should be evaluated at different temperatures and\nreaction times. Also, the temperature of different LAC under induction heating should be carefully\ncompared.\nResponse: We fully concur with the key comment raised by the reviewer and have supplemented a series\nof comparative experiments to clarify the effect of GaInNiSn MELAC. We evaluated the catalytic\nperformance of the GaInNiSn MELAC at three temperatures (400 °C, 500 °C, and 600 °C) and four reaction\ntimes (1 min, 2 min, 3 min, and 4 min), as shown in the Response Figs. 13,14. It can be observed that as\nthe reaction temperature increased from 400 °C to 500 °C, both the selectivity and the space-time yield\n(STY) for light olefins showed a marked increase. Upon further raising the reaction temperature to 600 °C,\nthe selectivity for H and CH rose significantly, resulting in a decrease in the selectivity and the STY for\n2 4\nlight olefins. From Response Fig. 14, different reaction times primarily affect the STY of light olefins. As\nthe reaction time increased from 1 minute to 3 minutes, the STY of light olefins rose from 90.2 to 181.5\n-59-\nmmol g \\minus1 h\\minus1. As the polypropylene plastic underwent complete depolymerization after 3 minutes of\ncat\nreaction, prolonging the reaction time decreased the STY of light olefins to 129.9 mmol g \\minus1 h\\minus1.\ncat\nIn fact, we used the constant-temperature heating function of the induction heating apparatus to\nmaintain the reaction temperature at 500 °C during the depolymerization process. Specifically, the\ntemperature of the LACs was monitored using a calibrated laser thermometer, with the output power of\nthe induction heating apparatus adjusted in real time to achieve constant-temperature heating.\nTherefore, different LACs maintained identical reaction temperatures throughout their depolymerization\nprocesses.\nResponse Fig. 13. Catalytic performance of the GaInNiSn MELAC at different temperatures (400 °C, 500 °C,\nand 600 °C). Reaction conditions: 1.0 g of PP plastic, 1.95 g of GaInNiSn MELAC, N feed gas at a flow\n2\nrate of 4 mL min\\text{--}1, and different temperatures for 3 min.\n-60-\nResponse Fig. 14. Catalytic performance of the GaInNiSn MELAC at different reaction times (1 min, 2 min,\n3 min, and 4 min). Reaction conditions: 1.0 g of PP plastic, 1.95 g of GaInNiSn MELAC, N feed gas at a\n2\nrate of 4 mL min\\text{--}1, and 500 °C for different reaction times.\nWe have revised the relevant description in Section 2.2 (Page 7, Line 144\\minus160):\nGenerally, reaction temperature and duration strongly influence the depolymerization process. At\ntemperatures below 500 °C, incomplete C\\text{--}C bond cleavage reduced the selectivity and STY of light olefins,\nwhereas increasing the temperature to 600 °C induced deep cracking and aromatization, generating\nsubstantial CH and aromatic byproducts that further deteriorate the STY of light olefins (Fig. S13)34, 35.\nof the reaction time led to a decrease in the STY of light olefins to 129.9 mmol g \\minus1 h\\minus1 (Fig. S14). In stark\ncat\ncontrast to a conventional resistance furnace, induction heating technologies provide rapid (heat-up rate >\n100°C s\\text{--}1), uniform (surface temperature variation of ±5°C), and precise (targeting the LAC directly)\nreaction conditions for polyolefin depolymerization (Figs. S13\\minus S17)16.\nWe have revised the relevant description in the Methods section (Page 14, Line 314\\minus317):\nThe temperature of the LACs was monitored using a calibrated laser thermometer (measuring\nwavelength 1.6 μm, temperature range 250\\text{--}1400 °C), with the output power of the induction heating\n-61-\napparatus adjusted in real time to achieve constant-temperature heating.\nWe have updated Figs. S13,S14 in the supporting information:\nFig. S13. Catalytic performance of the GaInNiSn MELAC at different temperatures (400 °C, 500 °C, and\n600 °C). Reaction conditions: 1.0 g of PP plastic, 1.95 g of GaInNiSn MELAC, N feed gas at a flow rate of\n2\n4 mL min\\text{--}1, and different temperatures for 3 min.\n-62-\nFig. S14. Catalytic performance of the GaInNiSn MELAC at different reaction times (1 min, 2 min, 3 min,\nand 4 min). Reaction conditions: 1.0 g of PP plastic, 1.95 g of GaInNiSn MELAC, N feed gas at a flow rate\n2\n4 mL min\\text{--}1, and 500 °C for different reaction times.\nACTION: Manuscript and Supporting Information amended\n3. The performance and structure of spent catalyst needs to be explored in detail.\nResponse: We sincerely appreciate the reviewer's insightful comment. We have conducted a\ncomprehensive characterisation of the spent GaInNiSn liquid alloy catalyst (after 120 hours of continuous\nreaction cycles) to explore its performance and structural changes:\nFirstly, we performed high-angle annular dark field scanning TEM (HAADF-STEM) analysis on the spent\nGaInNiSn MELAC (Response Fig. 15). The results indicate that the morphology of the spent GaInNiSn\nMELAC remained almost unchanged after 120 h of operation in the plastic depolymerization reaction,\nwithout Ni agglomeration observed. Secondly, the weight percentages of elements in the spent GaInNiSn\nMELAC measured by inductively coupled plasma-optical emission spectrometry (ICP-OES) showed no\nsignificant variation compared with the fresh sample (Response Table 5). XPS analysis confirms that the\nspent GaInNiSn MELAC exhibited no significant changes in electronic structure compared with the fresh\nsample (Response Fig. 16). Finally, the depolymerization performance of the spent GaInNiSn MELAC\nshowed a light olefin selectivity of 78.1% and a space-time yield of 178.8 mmol g \\minus1 h\\minus1 (Response Fig.\ncat\n17), which is equivalent to the catalytic performance of fresh GaInNiSn MELAC. These results confirm the\nexceptional stability of the quaternary GaInNiSn MELAC we designed.\n-63-\nResponse Fig. 15. HAADF-STEM image and corresponding EDS mapping of the spent GaInNiSn MELAC.\nResponse Fig. 16. XPS spectra of fresh and spent GaInNiSn MELACs.\n-64-\nResponse Fig. 17. Depolymerization performance of fresh and spent GaInNiSn MELACs. Reaction\nconditions: 1.0 g of polypropylene plastic, 1.95 g of spent GaInNiSn MELAC, N feed gas at a flow rate of\n2\n4 mL min\\text{--}1, and 500 °C for 3 min.\nResponse Table 5. ICP-OES elemental analysis of fresh and spent GaInNiSn MELACs\nSample Element Weight percentage (wt%)\nGa 61.23\nIn 28.69\nFresh GaInNiSn MELAC\nNi 6.01\nSn 4.07\nGa 62.15\nIn 27.84\nSpent GaInNiSn MELAC\nNi 6.29\nSn 3.72\n-65-\nWe have updated Section 2.3 (Page 11, Line 251–257) of the manuscript:\nFurthermore, we conducted characterisation analysis and performance testing on the recovered\nGaInNiSn MELAC (Figs. S30–S32 and Tables S10,S11). The results indicate no significant change in surface\nmorphology, elemental composition, and electronic structure compared with the fresh GaInNiSn MELAC.\nMeanwhile, the recovered GaInNiSn MELAC exhibited a 78.1% light olefin selectivity and a 178.8 mmol\ng \\minus1 h\\minus1 STY during the depolymerization of PP plastic. These values are equivalent to the catalytic\ncat\nperformance of the fresh GaInNiSn MELAC, demonstrating the recoverability and reusability of the\nGaInNiSn MELAC.\nWe have updated the Methods section (Page 15, Line 331–334) of the manuscript:\nOnce the reactor was cooled to ambient temperature, the LAC was recovered with a pipette and sealed\nin a reagent bottle containing 2wt% acetone for subsequent testing (Figs. S30,S31 and Tables S10,S11).\nThe recovered LAC can be reused after undergoing ultrasonic cleaning at 120 watts for 20 minutes (Fig.\nS32).\nWe have updated Figs. S30–S32 and Table S11 in the supporting information:\n-66-\nFig. S30. HAADF-STEM image and corresponding EDS mapping of the recovered GaInNiSn MELAC.\nFig. S31. XPS spectra of fresh and recovered GaInNiSn MELACs.\n-67-\nFig. S32. Depolymerization performance of fresh and recovered GaInNiSn MELACs. Reaction conditions:\n1.0 g of polypropylene plastic, 1.95 g of recovered GaInNiSn MELAC, N feed gas at a flow rate of 4 mL\n2\nmin\\text{--}1, and 500 °C for 3 min.\nTable S11. ICP-OES elemental analysis of fresh and recovered GaInNiSn MELACs\nSample Element Weight percentage (wt%)\nGa 61.23\nIn 28.69\nFresh GaInNiSn MELAC\nNi 6.01\nSn 4.07\nGa 62.15\nIn 27.84\nRecovered GaInNiSn MELAC\nNi 6.29\nSn 3.72\n-68-\nACTION: Manuscript and Supporting Information amended\n4. More experimental details of the outdoor photovoltaics-driven depolymerization system should be\nprovided. For example, the “continuous operation” is actually intermittent, as can be inferred from\nthe conditions of “500 °C for 3 min (each reaction)” in the legend of Figure 5c. Also, the rate and\nselectivity were almost unchanged within 120 hours, which is impossible considering the difference\nof light intensities during the day and at night. As an outdoor photovoltaics-driven experiment, the\nspecific date and time need to be provided. In addition, it is necessary to clarify whether 8.77 g of\nplastics and 11.69 g of “fresh” catalysts need to be added in each reaction during the “continuous\noperation”. Taking into account the discontinuity of the experiment and the very limited and\nspecific testing time, it is not recommended to claim that an outdoor photovoltaics-driven\ndepolymerization system with an annual capacity of 1.23 tons has been constructed.\nResponse: We thank the reviewer for the careful and insightful review of our manuscript. We sincerely\napologise for the insufficiency in the manuscript. We have supplemented Section 2.3 and the Methods\nsection of the manuscript with detailed information regarding the outdoor photovoltaics-driven\ndepolymerization system and have revised the caption for Fig. 5 in the manuscript. Additionally, we have\nremoved the inappropriate wording referring to an annual capacity of 1.23 tons from the manuscript and\nthe supporting information.\nThe conditions of “500 °C for 3 min (each reaction)” in the legend of Fig. 5c refer to the plastic feeding\namount every three minutes, instead of indicating intermittent operation. In fact, the reaction was\ncontinuously heated, with 8.77 g of plastic fragments introduced into the reactor every three minutes via\na customised continuous feed apparatus (Response Fig. 18). Therefore, a more accurate description\nwould be a feed rate of 2.92 g min\\minus1.\nThe rate and selectivity were almost unchanged within 120 hours since our outdoor photovoltaic system\nwas equipped with four 12 V\\text{--}200 Ah storage batteries (storage capacity of 9.6 kWh). These batteries\nstore photovoltaic power, which is then converted by inverters for induction heating. Meanwhile, the\nbatteries also stabilise power output and balance the effects of variations in weather and sunlight\nintensity. Therefore, the generation rate and selectivity were continuous and stable. Furthermore, the\n-69-\noutdoor system was constructed on the roof of the experimental building and operated continuously for\nover 120 hours between July 6th and July 20th, 2025 (daily from 8:30 to 16:30), with a reaction\ntemperature of 500 °C and an ambient temperature ranging from 22.3 to 28.1 °C (Response Fig. 19).\nThe GaInNiSn liquid alloy catalyst was placed into the reactor only before the commencement of the\nreaction and was neither added nor removed during continuous operation. Consequently, during the\ndepolymerization process, we only needed to feed the plastic into the reactor via the continuous feed\napparatus. We concur with the reviewer's perspective on the scale of the outdoor system and have\nremoved the inappropriate wording of an annual capacity of 1.23 tons from both the manuscript and the\nsupporting information.\nResponse Fig. 18. (a) Quartz tube reactor for the outdoor photovoltaics-driven depolymerization system.\n(b) Continuous feed apparatus.\n-70-\nResponse Fig. 19. (a) Outdoor sunlight intensity from July 6th to July 20th, 2025, in Dalian city, China. (b)\nPV power generation, battery power storage, and induction heating (IH) apparatus power consumption\nfrom July 6th to July 20th, 2025, in Dalian city, China.\nWe have updated Section 2.3 of the manuscript (Page 11, Line 233\\minus250):\nTo assess the scalability of this process for practical implementation, we constructed an outdoor\nphotovoltaics-driven depolymerization system in Dalian City, Liaoning Province, China. As illustrated in\nFig. 5a, the system comprises four photovoltaic panels (irradiation area of 10.3 m2, module efficiency of\n24%), an electromagnetic induction heating apparatus (operating power 380 Wh), a vacuum heat pipe\nreactor, and four storage batteries with a combined capacity of 9.6 kWh. This system was loaded with\n11.7 g of the GaInNiSn MELAC to recycle real-world polyolefin waste, consistent with the blends tested in\n-71-\nSection 2.2. The real-world waste fragments are conveyed into the reactor via a continuous feed\napparatus at a feed rate of 2.92 g min\\text{--}1 (Fig. S28). The process flow and unit schematics of the system\nare provided in Fig. 5b, with further details in the Methods section. The outdoor system operated\ncontinuously for 120 hours from 6th July to 20th July 2025 (daily from 08:30 to 16:30). Ambient\ntemperatures during operation ranged from 22.3 to 28.1 °C, with outdoor solar irradiance recorded in\nFig. S29a. Despite fluctuations in photovoltaic output, the energy supply to the reaction apparatus\nremained stable due to the battery buffer (Fig. S29b). As shown in Fig. 5c, the system achieved a light\nolefin production rate of 52.8 L h\\text{--}1 and selectivity of 71.5% (Table S9), summing up 6337 L light olefins\nover 120 hours and thus suggesting excellent operational stability. The energy consumption of the\ndepolymerization process by our system was calculated to be 3.8 kWh kg \\text{--}1. Notably, compared\nLight olefins\nwith other depolymerization technologies (Fig. 5d), our system offers over five times higher production\nrates and ten times longer stability, highlighting its significant advantages10.\nWe have updated the Methods section (Page 16, Line 345\\minus371) of the manuscript:\nThe outdoor photovoltaics-driven depolymerization system built in this study consisted of two\ncomponents: a solar power system and a waste plastic depolymerization system. The solar power system\nused four TY-450M photovoltaic panels (2278 × 1134 × 30 mm) with an irradiation area of 10.3 m2\n(module efficiency of 24%). Additionally, four 12 V\\text{--}200 Ah storage batteries (storage capacity of 9.6 kWh)\nwere equipped to store photovoltaic power, which is then converted by inverters for use in\ndepolymerization reactions. Meanwhile, the batteries also stabilise power output and balance the effects\nof variations in weather and sunlight intensity. The waste plastic depolymerization system used a\ncustomised vacuum heat pipe reactor, which comprised an outer pipe of 300 mm in length and 32 mm in\ndiameter, an inner pipe of 450 mm in length and 20 mm in diameter, and a vacuum layer of 300 mm in\nlength and 3 mm in thickness (Fig. S28a). The vacuum heat pipe reactor was fixed using an aluminium\nbracket (dimensions: 330 × 350 × 650 mm). Subsequently, post-consumer plastic product fragments (e.g.,\nfood packaging bags, take-away containers, drinking water bottle caps, milk bottles, beverage straws,\ntoothpaste tubes, foam boxes, reagent buckets, and medical ziplock bags) were loaded into the\ncontinuous feed apparatus and conveyed to the reactor via a screw rod at the left end of the apparatus\n(Fig. S28b). The continuous feed apparatus delivered plastic fragments into the inner tube at a feed rate\n-72-\nof 2.92 g min\\text{--}1. For the production of light olefins (C H , C H , and C H ), 11.7 g of the GaInNiSn MELAC\n2 4 3 6 4 8\nwas used. The GaInNiSn MELAC was placed into the reactor only before the commencement of the\nreaction and was neither added nor removed during continuous operation. The induction heating\napparatus was a JRHG-3 KW UHF ultra-high frequency induction heating apparatus (maximum output\npower: 3 kW; working frequency: 500\\text{--}1100 kHz) supplied by Jinrui Intelligent Technology Co., Ltd.\n(Dongguan, Guangdong Province, China). The outdoor system was constructed on the roof of the\nexperimental building and operated continuously for over 120 hours between July 6th and July 20th, 2025\n(daily from 8:30 to 16:30), with a reaction temperature of 500 °C and an ambient temperature ranging\nfrom 22.3 to 28.1 °C (Fig. S29). The generated light olefins were collected in aluminium foil gas sampling\nbags, and their detailed composition and corresponding percentages were determined via GC analysis\n(off-line mode).\nWe have updated Figs. S28,S29 in the supporting information:\n-73-\nFig. S28. (a) Vacuum heat pipe reactor for the outdoor photovoltaics-driven depolymerization system. (b)\nContinuous feed apparatus.\nFig. S29. (a) Outdoor sunlight intensity from July 6th to July 20th, 2025, in Dalian city, China. (b) PV power\ngeneration, battery power storage, and induction heating (IH) apparatus power consumption from July\n6th to July 20th, 2025, in Dalian city, China.\nACTION: Manuscript and Supporting Information amended\n5. It seems that compared to electric furnace heating, the major advantage of induction heating lies\nin the transient variation of temperature. Therefore, it is recommended to conduct a further\ndiscussion among different instantaneous heating technologies.\n-74-\nResponse: Many thanks to the reviewer for the careful review of our manuscript. We have supplemented\na comparative discussion of different instantaneous heating technologies (joule heating, induction\nheating, microwave heating) in the introduction of the revised manuscript:\nFor polyolefin plastic depolymerization to olefin monomers or light olefins, joule heating induces localised\nthermal inhomogeneities, triggering excessive side reactions (e.g., coking) that reduce the selectivity of\nthe target product15. Microwave heating is constrained by the low dielectric loss of polyolefins, resulting\nin suboptimal energy efficiency and difficulty in controlling heating uniformity and reaction processes,\nthus hindering the achievement of stable depolymerization36. In contrast, induction heating leverages the\nadvantage of transient temperature variation and enables rapid, precise temperature modulation,\nalleviating persistent temperature non-uniformity and suppressing side reactions37, 38.\nWe have updated the Introduction (Page 7, Line 150\\minus157) in the manuscript:\nIn stark contrast to a conventional resistance furnace, induction heating provides rapid (heat-up rate >\n100 °C s\\text{--}1), uniform (surface temperature variation of ±5 °C), and precise (targeting the LAC directly)\nreaction conditions for polyolefin depolymerization (Figs. S13\\minus S17)16. Compared with this technique,\nJoule heating generally induces localised thermal inhomogeneities, triggering excessive side reactions\n(e.g., coking) that reduce the selectivity of the target product15. Microwave heating is constrained by the\nlow dielectric loss of polyolefins, resulting in suboptimal energy efficiency and difficulty in controlling\nheating uniformity and reaction processes, thus hindering the achievement of stable depolymerization36\nACTION: Manuscript and Supporting Information amended\n6. It is suggested to provide data of conversion and mass/carbon balance.\nResponse: We genuinely thank you for your constructive suggestions and deeply apologise for the\nomission of the conversion and mass/carbon balance in the manuscript. We have supplemented\nconversion, mass balance, and the mass of residues (M ) with calculation formulas and data tables:\nResidues\n\\left(\\begin{array}{c} M -M \\end{array}\\right)\nConversion=\\left(\\begin{array}{c} Reactor,0 Reactor,t \\end{array}\\right)\\times 1 0 0 % (R2)\n\\left(\\begin{array}{c} M \\end{array}\\right)\nPlastic\n-75-\n-76-\nM a s s b a la n c e =\\left(\\begin{array}{c} 2 n\nH 2\n+ 1 6 n\nC H 4\n+ 2 8 n\nC H2 4\n+ 3 0 n\nC H2 6\n+\nM\n4 2 n\nC\nP la stic\nH3 6\n+ 4 4 n\nC H3 8\n+ 5 6 n\nC H4 8\n+ M\nR esid u es\n\\end{array}\\right)\n\\times 1 0 0 % (R3)\nM\nR esid u es\n= M\nR ea cto r,t\n- M\nQ u a rtz tu b e\n- M\nQ u a rtz w o o l\n- M\nLiq u id a llo y ca ta lyst\n(R4)\nwhere M denotes the mass of the reactor before reaction (comprising the quartz tube, quartz wool,\nReactor,0\nliquid alloy catalyst, and plastic), M denotes the mass of the reactor after reaction, and M\nReactor,t Plastic\ndenotes the mass of plastic added to the reactor before reaction; n represents the amount of gaseous\ni\nproducts i (including H , CH , C H , C H , C H , C H , C H , and C H ), M , M , and M\n2 4 2 4 2 6 3 6 3 8 4 8 4 10 Quartz tube Quartz wool Liquid\nrepresent the masses of the quartz tube, quartz wool, and liquid alloy catalyst, respectively.\nalloy catalyst\nResponse Table 6. The detailed conversion in the polypropylene plastic depolymerization\nM (g) M (g) M (g) M (g) M (g) M (g) Conversion (%)\nQuartz tube Quartz wool Liquid alloy catalyst Plastic Reactor,0 Reactor,t\n415.25 0.23 1.95 1.00 418.44 417.47 96.0\nReaction conditions: 1.00 g of PP plastic, 1.95 g of GaInNiSn MELAC, N feed gas at a flow rate of 4 mL\n2\nmin\\text{--}1, and 500 °C for 3 min.\nResponse Table 7. The detailed mass balance in the polypropylene plastic depolymerization\nM n n n n n n n M Mass\nPlastic H2 CH4 C2H4 C2H6 C3H6 C3H8 C4H8 Residues\n(g) (mmol) (mmol) (mmol) (mmol) (mmol) (mmol) (mmol) (g) balance (%)\n1.00 0.44 0.91 1.26 2.17 15.81 1.05 2.08 0.04 100\nReaction conditions: 1.00 g of PP plastic, 1.95 g of GaInNiSn MELAC, N feed gas at a flow rate of 4 mL\n2\nmin\\text{--}1, and 500 °C for 3 min.\nWe have updated the Methods section of the manuscript (Page 15, Line 342\\minus344):\nThe detailed conversion and mass balance analysis for the depolymerization reaction of polypropylene\nplastic is recorded in Tables S12,S13.\nWe have updated the calculation formula and date to Tables S12,S13 in the supporting information:\nTable S12. The detailed conversion in the polypropylene plastic depolymerization\nM (g) M (g) M (g) M (g) M (g) M (g) Conversion (%)\nQuartz tube Quartz wool Liquid alloy catalyst Plastic Reactor,0 Reactor,t\n415.25 0.23 1.95 1.00 418.44 417.47 96.0\nReaction conditions: 1.00 g of PP plastic, 1.95 g of GaInNiSn MELAC, N feed gas at a flow rate of 4 mL\n2\nmin\\text{--}1, and 500 °C for 3 min. M , M , and M represent the masses of the quartz\nQuartz tube Quartz wool Liquid alloy catalyst\ntube, the quartz wool, the liquid alloy catalyst, and the plastic added to the reactor before reaction,\nrespectively.\n-77-\nC o n v e r s io n =\\left(\\begin{array}{c} M\nR ea cto r,0\nM\nP\n-\\la\nM\nstic\nR ea cto r,t\n\\end{array}\\right)\n\\times 1 0 0 % (S9)\nwhere M denotes the mass of the reactor before reaction (comprising the quartz tube, quartz wool,\nReactor,0\nliquid alloy catalyst, and plastic), M denotes the mass of the reactor after reaction, and M\nReactor,t Plastic\ndenotes the mass of plastic added to the reactor before reaction.\nTable S13. The detailed mass balance in the polypropylene plastic depolymerization\nM n n n n n n n M Mass\nPlastic H2 CH4 C2H4 C2H6 C3H6 C3H8 C4H8 Residues\n(g) (mmol) (mmol) (mmol) (mmol) (mmol) (mmol) (mmol) (g) balance (%)\n1.00 0.44 0.91 1.26 2.17 15.81 1.05 2.08 0.04 100\nReaction conditions: 1.00 g of PP plastic, 1.95 g of GaInNiSn MELAC, N feed gas at a flow rate of 4 mL\n2\nmin\\text{--}1, and 500 °C for 3 min.\n-78-\nM a s s b a la n c e =\\left(\\begin{array}{c} 2 n\nH 2\n+ 1 6 n\nC H 4\n+ 2 8 n\nC H2 4\n+ 3 0 n\nC H2 6\n+\nM\n4 2 n\nC\nP la stic\nH3 6\n+ 4 4 n\nC H3 8\n+ 5 6 n\nC H4 8\n+ M\nR esid u es\n\\end{array}\\right)\n\\times 1 0 0 % (S4)\nM\nR esid u es\n= M\nR ea cto r,t\n- M\nQ u a rtz tu b e\n- M\nQ u a rtz w o o l\n- M\nLiq u id a llo y ca ta lyst\n(S11)\nwhere n represents the amount of substance of gaseous products i (including H , CH , C H , C H , C H ,\ni 2 4 2 4 2 6 3 6\nC H , C H , and C H ), M denotes the mass of the residues; M , M , M , and\n3 8 4 8 4 10 Residues Reactor,t Quartz tube Quartz wool\nM represent the masses of the reactor after reaction, the quartz tube, the quartz wool, and\nLiquid alloy catalyst\nthe liquid alloy catalyst, respectively.\nACTION: Manuscript and Supporting Information amended\nReferences\n1. Chen LN, et al. Ternary NiMo-Bi liquid alloy catalyst for efficient hydrogen production from methane pyrolysis.\nScience 381, 857–861 (2023).\n2. Wang M, et al. Complete hydrogenolysis of mixed plastic wastes. Nat Chem Eng 1, 376–384 (2024).\n3. Yun FF, et al. Voltage-induced penetration effect in liquid metals at room temperature. Natl Sci Rev 7, 366–\n372 (2020).\n4. Lin YH, Sharratt PN, Garforth AA, Dwyer J. Catalytic conversion of polyolefins to chemicals and fuels over\nvarious cracking catalysts. Energy & Fuels 12, 767–774 (1998).\n5. Lovás P, Hudec P, Jambor B, Hájeková E, Hornácek M. Catalytic cracking of heavy fractions from the pyrolysis\nof waste HDPE and PP. Fuel 203, 244–252 (2017).\n6. Zhao YZ, Wang W, Jing XD, Gong XZ, Wen H, Deng YX. Catalytic cracking of polypropylene by using Fe-SBA-15\nsynthesized in an acid-free medium for production of light hydrocarbon oils. J Anal Appl Pyrol 146, 104755\n(2020).\n7. Lin YH, Yang MH. 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Liquid metal-based thermal interface materials with a high thermal conductivity for\nelectronic cooling and bioheat-transfer applications. Appl Therm Eng 192, 116937 (2021).\n32. Monkhorst HJ, Pack JD. Special Points for Brillouin-Zone Integrations. Phys Rev B 13, 5188–5192 (1976).\n-79-\n33. Kresse G, Furthmuller J. Efficient iterative schemes for ab initio total-energy calculations using a plane-wave\nbasis set. Phys Rev B 54, 11169–11186 (1996).\n34. Zhang W, et al. Low-temperature upcycling of polyolefins into liquid alkanes via tandem cracking-alkylation.\nScience 379, 807–811 (2023).\n35. Miao YX, Zhao YX, Waterhouse GIN, Shi R, Wu LZ, Zhang TR. Photothermal recycling of waste polyolefin\nplastics into liquid fuels with high selectivity under solvent-free conditions. Nat Commun 14, 4242 (2023).\n36. Qin JB, Wu FY, Dou YB, Zhao D, Hélix-Nielsen C, Zhang WJ. Advanced Catalysts for the Chemical Recycling of\nPlastic Waste. Adv Mater 37, 202418138 (2025).\n37. Dong Q, Hu S, Hu L. Electrothermal synthesis of commodity chemicals. Nat Chem Eng 1, 680–690 (2024).\n38. Yang HM, et al. Distributed electrified heating for efficient hydrogen production. Nat Commun 15, 3868\n(2024).\n-80-"}, {"round": 2, "reviewer_comments": {"reviewer_1": "The authors have addressed most of the questions addressed in the original review of their work. In particular, the reviewer appreciates the increased detail the authors have provided about their experimental apparatus and the calculation of rate of product formation per mass of catalyst. There are, however, several of issues that have not been adequately addressed. These are as follows:\n1. Fig. S16 clarifies that the GaInNiSn MELAC prior to reaction is supported by its high surface tension on the quartz wool at the bottom of the reactor and the polymer is placed as a powder above it. N2 is fed below the quartz wool to remove the gaseous products as they are formed. What is not clear though, is what happens when the catalyst-polymer mass is raised to 500oC. Does the flowing gas turn the catalyst-polymer mass into fluidized slurry bed consisting of droplet of molten catalyst dispersed in the molten polymer in which there are gas bubbles as well? How and where is the temperature measured and how the temperature rise and fall during the 3 min of RF heating? Also, is it correct to view the molten catalyst as the receptor of the RF energy? Is the flow rate of gas change the size of the molten catalyst droplets and hence the area per unit catalyst mass on which contact occurs with the molten polymer? Answers to all these questions are need to appreciate how and why the process presented works.\n2. The authors properly calculate the STY (space time yield) in the revised manuscript and compare the values of STY that they observe to those they calculate for other studies conducted in the temperature range of 400-500oC. This is appropriate. However, in doing so, they no longer compare their results to the dehydrogenation-ethenolysis work reported in ref. 25. As noted in the original review, the STY calculated in for that work based on the active component, WO3/SiO2 is 62.5 to 200 mmol gcat−1 h−1 at 320oC which is the in the same order of magnitude as that for the MELAC catalyst used in the present study. This should be properly noted in a further revised version of the study.\n3. The authors should try to explain why GaInNiSn MELAC exhibits superior performance to the other MELAC catalysts. Does this composition exhibit superior catalytic properties and, if so, why? Alternatively is GaInNiSn MELAC a better RF susceptor and form smaller metal droplets than other metal alloys because is has a lower surface tension?", "reviewer_2": "The authors have modified the manuscript and the supporting information along the lines suggested by the referees. This clearly strengthened the manuscript and I feel that it is now ready for publication in NCOMMS.", "reviewer_3": "The authors did their best to answer each comment, question, concern and modified the manuscript properly. I recommend to accept this version directly."}, "author_response": "Ref. No.: NCOMMS-25-93184A\nTitle: Interfacial Configurational Entropy Tuning Strategy Enabling Liquid Alloys for\nEfficient Depolymerization of Polyolefin Waste\nWe sincerely appreciate the editor and all the reviewers for their efforts and insightful comments, and\nwe respond in a point-by-point manner below.\n-1-\nReviewer #1:\nThe authors have addressed most of the questions addressed in the original review of their work. In\nparticular, the reviewer appreciates the increased detail the authors have provided about their\nexperimental apparatus and the calculation of rate of product formation per mass of catalyst. There are,\nhowever, several of issues that have not been adequately addressed. These are as follows:\nResponse: Many thanks to the reviewer for the careful review of our manuscript. The constructive\nconcerns provided have been invaluable in enhancing the quality of our work. We deeply appreciate the\nopportunity to address these insightful questions. Each of your comments has been carefully considered,\nleading us to enhance our manuscript by incorporating detailed explanations and improvements across\nall the points you raised.\n1. Fig. S16 clarifies that the GaInNiSn MELAC prior to reaction is supported by its high surface tension\non the quartz wool at the bottom of the reactor and the polymer is placed as a powder above it. N2\nis fed below the quartz wool to remove the gaseous products as they are formed. What is not clear\nthough, is what happens when the catalyst-polymer mass is raised to 500oC. Does the flowing gas\nturn the catalyst-polymer mass into fluidized slurry bed consisting of droplet of molten catalyst\ndispersed in the molten polymer in which there are gas bubbles as well? How and where is the\ntemperature measured and how the temperature rise and fall during the 3 min of RF heating? Also,\nis it correct to view the molten catalyst as the receptor of the RF energy? Is the flow rate of gas\nchange the size of the molten catalyst droplets and hence the area per unit catalyst mass on which\ncontact occurs with the molten polymer? Answers to all these questions are need to appreciate\nhow and why the process presented works.\n1.1. Fig. S16 clarifies that the GaInNiSn MELAC prior to reaction is supported by its high surface tension\non the quartz wool at the bottom of the reactor and the polymer is placed as a powder above it. N2\nis fed below the quartz wool to remove the gaseous products as they are formed. What is not clear\nthough, is what happens when the catalyst-polymer mass is raised to 500oC. Does the flowing gas\nturn the catalyst-polymer mass into fluidized slurry bed consisting of droplet of molten catalyst\ndispersed in the molten polymer in which there are gas bubbles as well?\n-2-\nResponse: We genuinely thank you for your constructive suggestions and deeply apologize for the\nincompleteness of experimental details in the manuscript. To determine whether the reaction catalyst\nbed is a fixed bed or a fluidized bed, we calculated the critical fluidization velocity (u ) and Reynolds\nmf\nnumber (Re ) for this catalyst bed using the following formula1:\nmf\nd2(\n\\rho -\\rho\n)\ng\nu = p p g , Re <20 (1)\nmf 1650\\mu mf\ng\nd \\rho u\nRe = p g mf (2)\nmf \\mu\ng\nwhere d denotes the solid particle size in meters, \\rho denotes the solid particle density in kg m\\minus3, \\rho\np p g\ndenotes the fluidizing medium density in kg m\\minus3, g denotes the gravitational acceleration taken as 9.81\nm s\\minus2, and \\mu denotes the fluidizing medium viscosity in Pa·s. Among these, d is 0.3 × 10\\minus3 m, \\rho is taken\ng p p\nas 905 kg m\\minus3, \\rho is 1.25 kg m\\minus3, and \\mu is 1.78 × 10\\minus5 Pa·s. The u for this catalyst bed was calculated to\ng g mf\nbe 326.8 mL min\\minus1 (Re was 0.57 < 20), which is significantly greater than the actual carrier gas flow rate\nmf\n(4 mL min\\minus1). Therefore, the flowing gas does not turn the catalyst-polymer mass into a fluidized slurry\nbed. Furthermore, we recorded a video (Video 1) of the system under carrier gas flow (4 mL min\\minus1),\nconfirming that neither fluidization nor gas bubble formation occurs under the N stream.\n2 in the supporting information:\nTo determine whether the reaction catalyst bed is a fixed bed or a fluidized bed, we calculated the critical\nfluidization velocity (u ) of this catalyst bed using the following formula1:\nmf\nd2(\n\\rho -\\rho\n)\ng\nu = p p g , Re <20 (S9)\nmf 1650\\mu mf\ng\nd \\rho u\nRe = p g mf (S10)\nmf \\mu\ng\nwhere d denotes the solid particle size in meters, \\rho denotes the solid particle density in kg m\\minus3, \\rho\np p g\ndenotes the fluidizing medium density in kg m\\minus3, g denotes the gravitational acceleration taken as 9.81\n-3-\nm s\\minus2, and \\mu denotes the fluidizing medium viscosity in Pa·s. Among these, d is 0.3 × 10\\minus3 m, \\rho is taken\ng p p\nas 905 kg m\\minus3, \\rho is 1.25 kg m\\minus3, and \\mu is 1.78 × 10\\minus5 Pa·s. The u for this catalyst bed was calculated to\ng g mf\nbe 326.8 mL min\\minus1 (Re was 0.57 < 20), which is significantly greater than the actual carrier gas flow rate\nmf\n(4 mL min\\minus1). Therefore, the flowing gas does not turn the catalyst-polymer mass into a fluidized slurry\nbed. Furthermore, we recorded videos of the catalyst bed without (Video 1) and with (Video 2) induction\nheating conditions, confirming that the current gas flow rate neither changes the size of molten catalyst\ndroplets nor affects the contact area between the molten catalyst and the molten polymer.\nACTION: Supporting Information amended\n1.2. How and where is the temperature measured and how the temperature rise and fall during the 3\nmin of RF heating?\nResponse: We thank you for your insightful comment and deeply apologize for the inadequate\ndescription of the temperature measurement. The indoor experimental setup is depicted in Response Fig.\n1, comprising a depolymerization reactor, a laser thermo-detector, a thermo-detector control box, and\nan induction heating apparatus. Before the experiment, we calibrated the laser thermometer by K-type\nthermocouple to correct systematic errors such as the emissivity of the LAC and quartz tube, the\ntransmission and refraction of the quartz tube, and optical path loss, ensuring the accurate laser\nthermometer readings. The calibrated laser thermometer was employed to measure the temperature of\nthe LAC, with the laser spot position shown in Response Fig. 2a. Furthermore, the temperature rise and\nfall curve during the induction heating process is shown in Response Fig 2b. The excellent electrical\nconductivity of the LAC enabled it to reach the reaction temperature within 5 seconds. After the induction\nheating apparatus was turned off, the temperature of LAC fell to 250 °C within 30 seconds. The cross-\nsectional area of the liquid alloy catalyst was calculated as 37.7 mm2, which is significantly larger than\nthe spot area of the laser thermometer (3.14 mm2). Considering the thermal conductivity of liquid metal\nreaches 23.7 W m\\minus1·K\\minus1, it can be thought that the overall temperature of the liquid metal is\nuniform under steady state (500 °C). Furthermore, we conducted COMSOL calculations to confirm the\nhighly uniform temperature distribution of the LAC (Response Fig. 3). Consequently, we can measure the\ntemperature of the LAC accurately by positioning the spot of the laser thermometer on the surface of the\nLAC.\n-4-\nResponse Fig. 1. Indoor experimental setup, comprising a depolymerization reactor, a laser thermo-\ndetector, a thermo-detector control box, an induction heating apparatus, and a gas chromatograph.\nResponse Fig. 2. (a) Digital photograph of laser spot position. (b) Temperature rise and fall curve of the\nLAC during induction heating.\n-5-\nResponse Fig. 3. (a) Temperature variation of the liquid alloy catalyst during induction heating. (b)\ntemperature distribution of the liquid alloy catalyst via induction heating in a steady state.\nTo clarify these experimental details, we have revised the Methods section in the manuscript (Page 13,\nLine 291\\minus294 and Page 14, Line 316\\minus334):\nThe indoor experimental setup is depicted in Fig. S15, comprising a depolymerization reactor, a laser\nthermo-detector, a thermo-detector control box, an induction heating apparatus (Ambrell EASYHEAT\n0224, operating at a frequency of 150\\text{--}400 kHz, with a maximum output of 2.4 kW), and a gas\nchromatograph.\nBefore the experiment, we calibrated the laser thermometer by K-type thermocouple to correct\nsystematic errors such as the emissivity of the LAC and quartz tube, the transmission and refraction of\nthe quartz tube, and optical path loss, ensuring the accurate laser thermometer readings. The calibrated\nlaser thermometer was employed to measure the temperature of the LAC, with the laser spot position\nshown in Fig. S17a. Furthermore, the temperature rise and fall curve during the induction heating process\nis shown in Fig S17b. The excellent electrical conductivity of the LAC enabled it to reach the reaction\ntemperature within 5 seconds. After the induction heating apparatus was turned off, the temperature of\nLAC fell to 250 °C within 30 seconds. For a typical catalytic experiment, nitrogen gas was continuously\npurged at a flow rate of 20 mL min\\minus1 for 10 min to exhaust residual air. A calibrated laser thermometer\n(measuring wavelength 1.6 μm, temperature range 250\\text{--}1400 °C) was positioned 20 cm away from the\nreactor to record the LAC temperature, with the output power of the induction heating apparatus\n-6-\nadjusted in real time to achieve constant-temperature heating. The cross-sectional area of the LAC was\ncalculated as 37.7 mm2, significantly larger than the spot area of the laser thermometer (3.14 mm2).\nConsidering the thermal conductivity of LAC reaches 23.7 W m\\minus1·K\\minus1, it can be thought that the overall\ntemperature of the LAC is uniform under steady state (500 °C). Furthermore, we conducted COMSOL\ncalculations to confirm the highly uniform temperature distribution of the LAC (Fig. S18). Consequently,\nwe can measure the temperature of the LAC accurately by positioning the spot of the laser thermometer\non the surface of the LAC.\nWe have added Fig. S15, S17 and S18 in the supporting information:\nFig. S15. Indoor experimental setup, comprising a depolymerization reactor, a laser thermo-detector, a\nthermo-detector control box, an induction heating apparatus, and a gas chromatograph.\nFig. S17. (a) Digital photograph of laser spot position. (b) Temperature rise and fall curve of the GaInNiSn\nMELAC during induction heating.\n-7-\nFig. S18. (a) Temperature variation of the liquid alloy catalyst during induction heating. (b) temperature\ndistribution of the liquid alloy catalyst via induction heating in a steady state.\nACTION: Manuscript and Supporting Information amended\n1.3. Also, is it correct to view the molten catalyst as the receptor of the RF energy?\nResponse: We genuinely thank you for your constructive suggestions. The LAC is the receptor of the RF\nenergy, with a magneto-thermal conversion mechanism of eddy-current heating due to its high\nconductivity. We measured the conductivity of the GaInNi LELAC and the GaInNiSn MELAC using the Hall\neffect measurement, as shown in Response Table 1. Both the GaInNi LELAC and the GaInNiSn MELAC\nexhibited excellent electrical conductivity, with values of 3.53 × 104 Ω\\minus1·cm\\minus1 and 3.55 × 104 Ω\\minus1·cm\\minus1,\nrespectively. In contrast, insulating plastic particles are not capable of responding to RF energy. Therefore,\nit is correct to view the molten catalyst as the receptor of RF energy.\nResponse Table 1. Comparison of the conductivity of the GaInNi LELAC and the GaInNiSn MELAC\nSample Resistivity (Ω·cm) Conductivity (Ω\\minus1·cm\\minus1)\nGaInNi 2.83 × 10\\minus5 3.53 × 104\nGaInNiSn 2.82 × 10\\minus5 3.55 × 104\nWe have revised the relevant description in Section 2.1 of the manuscript (Page 5, Line 94\\minus96):\nThe Hall effect measurement revealed that the GaInNi LELAC and GaInNiSn MELAC exhibit excellent\nelectrical conductivity (Table S3), serving as the receptor of induction heating.\n-8-\nWe have updated the Supplementary Note 3 and Table S3 in the supporting information:\nWe measured the resistivity and conductivity of the GaInNi LELAC and the GaInNiSn MELAC using the Hall\neffect measurement, as shown in Table S3. The conductivities of the GaInNi LELAC and the GaInNiSn\nMELAC were of the same order of magnitude, at 3.53 × 104 Ω\\minus1·cm\\minus1 and 3.55 × 104 Ω\\minus1·cm\\minus1, respectively,\ndiffering by only 0.57%. Therefore, the GaInNi LELAC and the GaInNiSn MELAC exhibited nearly identical\nmagneto-thermal conversion efficiency, as the receptor of induction heating. In contrast, insulating\nplastic particles are not capable of responding to RF energy.\nTable S3. Comparison of the conductivity of the GaInNi LELAC and the GaInNiSn MELAC\nSample Resistivity (Ω·cm) Conductivity (Ω\\minus1·cm\\minus1)\nGaInNi 2.83 × 10\\minus5 3.53 × 104\nGaInNiSn 2.82 × 10\\minus5 3.55 × 104\nACTION: Manuscript and Supporting Information amended\n1.4. Is the flow rate of gas change the size of the molten catalyst droplets and hence the area per unit\ncatalyst mass on which contact occurs with the molten polymer?\nResponse: We thank the reviewer for the careful and insightful review of our manuscript. The flow rate\nof gas does not change the size of the molten catalyst droplets, as the current carrier gas (4 mL min\\minus1) is\ntoo low to even fluidize the polymer particles. Furthermore, we recorded videos of the catalyst bed\nwithout (Video 1) and with (Video 2) induction heating conditions, confirming that the current gas flow\nrate neither changes the size of molten catalyst droplets nor affects the contact area between the molten\ncatalyst and the molten polymer.\nTo clarify these experimental details, we have uploaded Videos 1,2 and updated the Supplementary\nNote 2 in the supporting information:\nFurthermore, we recorded videos of the catalyst bed without (Video 1) and with (Video 2) induction\n-9-\nheating conditions, confirming that the current gas flow rate neither changes the size of molten catalyst\ndroplets nor affects the contact area between the molten catalyst and the molten polymer.\nACTION: Supporting Information amended\n2. The authors properly calculate the STY (space time yield) in the revised manuscript and compare\nthe values of STY that they observe to those they calculate for other studies conducted in the\ntemperature range of 400-500oC. This is appropriate. However, in doing so, they no longer compare\ntheir results to the dehydrogenation-ethenolysis work reported in ref. 25. As noted in the original\nreview, the STY calculated in for that work based on the active component, WO3/SiO2 is 62.5 to\n200 mmol gcat\\minus1 h\\minus1 at 320oC which is the in the same order of magnitude as that for the MELAC\ncatalyst used in the present study. This should be properly noted in a further revised version of the\nstudy.\nResponse: We thank the reviewer for their critical suggestions. In the further revised version, we have\nupdated Fig. 3b of the manuscript and added proper descriptions. We calculated the space-time yield\n(STY) of light olefins for the tandem catalytic cracking and isomerizing ethenolysis (CIE) reaction based\non the active components of WO /SiO and Na/γ-Al O . Under conditions of 320 °C at 1 bar and 320 °C\n3 2 2 3\nat 15 bar, the STY for the CIE reaction is 56.4 and 203.2 mmol g \\minus1 h\\minus1, respectively. These values are in\ncat\nthe same order of magnitude as the STY of the GaInNiSn MELAC used in this study. As shown in Response\nFig. 4, we have added CIE data points to the performance comparison plot.\n-10-\nResponse Fig. 4. Comparison of the performance of different depolymerization and recycling\ntechnologies, including the conversion of plastic, the selectivity of light olefins, and the space-time yield\nof light olefins2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15.\nWe have revised the relevant description in the Introduction of the manuscript (Page 4, Line 59\\minus63):\nDisruptively, the tandem catalytic cracking and isomerizing ethenolysis process (CIE) ingeniously\nintegrates olefin isomerization and olefin metathesis, enhancing monomer selectivity to attain a high\nC H space-time yield of 135.5 mmol g \\minus1 h\\minus1 in polyolefin depolymerization, representing the highest\n3 6 cat\nlevel attained to date.\nWe have revised the relevant description in Section 2.2 of the manuscript (Page 9, Line 182\\minus185):\nWhen benchmarked against state-of-the-art catalysts, the GaInNiSn LAC is far ahead in terms of the STY\nand monomer selectivity (Fig. 3b and Table S7). Notably, the STY of light olefins for the GaInNiSn MELAC\n(1 bar) is threefold that of CIE under atmospheric pressure (1 bar), even approaching the STY under high\npressures (15 bar).\nWe have updated Fig. 3 in the manuscript:\n-11-\nFig. 3. Depolymerization performance of the GaInNiSn MELAC. (a) Comparison of depolymerization\nperformance between ternary and quaternary liquid alloy catalysts (all active metals being Ni). The\ndashed line denotes the average STY of the ternary LACs (105.35 mmol g \\minus1 h\\minus1). Reaction conditions:\ncat\n1.0 g of polypropylene plastic, 1.95 g of different LACs (SnBiNi, InBiNi, InSnNi, GaBiNi, GaSnNi, GaInNi,\nand GaInNiSn), N feed gas at a flow rate of 4 mL min\\text{--}1, and 500 °C for 3 min. (b) Comparison of the\n2\nperformance of different depolymerization and recycling technologies, including the conversion of plastic,\nthe selectivity of light olefins, and the space-time yield of light olefins2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15. (c)\n-12-\nSpace-time yield of light olefins and selectivity of gaseous products during depolymerization of diverse\npolyolefin plastics. Reaction conditions: 1.0 g of reactants (PP, LDPE, HDPE, PS, POE, and SBS), 1.95 g of\nGaInNiSn MELAC, N feed gas at a flow rate of 4 mL min\\text{--}1, and 500 °C for 3 min. PP+LDPE, PP+HDPE,\ncorresponding polymer. Mix denotes the equal mass ratio mixture of these six reactants. (d) Space-time\nyield of light olefins and selectivity of gaseous products during depolymerization of real-world plastic\nwaste. Reaction conditions: 1.0 g of reactants (food packaging bags, take-away containers, drinking\nwater bottle caps, milk bottles, beverage straws, toothpaste tubes, foam boxes, reagent buckets, and\nmedical ziplock bags), 1.95 g of GaInNiSn MELAC, N feed gas at a flow rate of 4 mL min\\text{--}1, and 500 °C for\n2\n3 min. Mix denotes the equal mass ratio mixture of these nine reactants.\nWe have updated Table S7 in the supporting information:\n-13-\nTable S7. Comparison of polyolefin plastic recycling methods in the literature, including the conversion of plastic, the selectivity of light\nolefins, and the space-time yield of light olefins\nCarrier\ngas\nMass of Mass of and Reaction Reaction Reaction Space-time\nPolyolefin Types of Conversion Selectivity\nMethod polyolefin catalyst flow temperature pressure time yield (mmol\nplastics catalysts (%) (%)\nplastics (mg) (mg) rate (℃) (bar) (min) g \\minus1 h\\minus1)\ncat\n(mL\nmin\\minus1)\nHZSM-5\nHUSY\nCatalytic N\npyrolysis2 50\nSAHA\nAl MCM-41\nCatalytic\ncracking Waste N\n2\n667\\minus4000 FCC-ECAT 4000 430\\minus527 1 900 26.7\\minus45.2 4.3\\minus9.5 0.06\\minus1.43\n(mixed gas PP/HDPE 30\noil/wax)3\nCatalytic N\ncracking4 300\nCatalytic Waste N\n2\n75\\minus90 E-Cat 250\\minus300 450\\minus460 1 30 85.0\\minus95.0 3.20\\minus28.2 0.46\\minus2.89\ncracking5, 6 PP/PE 600\nCatalytic N\npyrolysis7 700\nCatalytic N\ncracking8 12000\n-14-\nCatalytic N\npyrolysis9 400\nZSM-5\nE-Cat\nE-\nCatalytic\nPP/PE 0.4 Cat+ZSM-5 16\\minus60 / 600 1 100 75.0\\minus90.0 13.3\\minus24.2 0.05\\minus0.08\npyrolysis10\nE-\nCat+HZSM-\nTandem PE/ Ar\ncracking11 Oligomer 40\nCat-2\nLSP-Z100\nTandem N\ncracking12 10\nP-HZSM-5\nH-ZSM-5\nRapid joule He\nPE/PP 10\\minus12 Carbon 967.6 540\\minus750 1 1 90.0 45.0\\minus74.0 9.08\\minus15.0\nheating13 25\nfibre paper\nElectrified\nGraphite\nspatiotemporal PP 100\\minus1000 / Ar 600 1 35 100.0 35.5 6.28\\minus9.57\nfelt\nheating14\nCatalytic\ncracking and Waste WO /SiO C H\n3 2 2 4\n1000 800 320 1\\minus15 90 100.0 26.9\\minus97.0 56.4\\minus203.2\nisomerizing PP/PE Na/γ-Al O 10-200\n2 3\nethenolysis15\nWaste N\nPP/PE 4\nACTION: Manuscript and Supporting Information amended\n-15-\n3. The authors should try to explain why GaInNiSn MELAC exhibits superior performance to the other\nMELAC catalysts. Does this composition exhibit superior catalytic properties and, if so, why?\nAlternatively is GaInNiSn MELAC a better RF susceptor and form smaller metal droplets than other\nmetal alloys because is has a lower surface tension?\nResponse: We completely agree with the reviewer's suggestion that we should explain why the GaInNiSn\nMELAC exhibits superior catalytic performance. Accordingly, we measured the resistivity and conductivity\nof the GaInNi LELAC and the GaInNiSn MELAC using the Hall effect measurement, as shown in Response\nTable 1. The conductivities of the GaInNi LELAC and the GaInNiSn MELAC were of the same order of\nmagnitude, at 3.53 × 104 Ω\\minus1·cm\\minus1 and 3.55 × 104 Ω\\minus1·cm\\minus1, respectively, differing by only 0.57%.\nTherefore, the GaInNi LELAC and the GaInNiSn MELAC exhibited nearly identical magneto-thermal\nconversion efficiency, as the receptor of induction heating. In contrast, insulating plastic particles are not\ncapable of responding to RF energy. As shown in Video 1, the GaInNiSn MELAC does not form small metal\ndroplets due to the high u . Consequently, we attribute the enhanced catalytic performance of the\nmf\nGaInNiSn MELAC to our proposed entropy engineering strategy. Specifically, we increased the interfacial\nconfigurational entropy (S ) of the liquid alloy by introducing the regulatory metal Sn. In stark\nif-config\ncontrast to the binary or ternary liquid alloy catalysts, the increase in the S of the GaInNiSn MELAC\nif-config\nattenuates interfacial Gibbs free energy, thereby modulating Ni active sites and promoting their\nenrichment on the Ga interface. Furthermore, Sn electronically modifies Ni to form Niδ\\minus–Snδ+ sites at the\nGaIn interface, activating C\\text{--}H bonds for selective depolymerization via \\beta-scission. Meanwhile, the lower\nsurface tension of the GaInNiSn MELAC provides a larger solid-liquid contact area for plastic\ndepolymerization, which is one reason for its superior catalytic performance.\nTo further underscore the proposed strategy for designing LAC catalysts, we synthesized other ternary\nLACs with an identical active metal content (10wt% Ni): SnBiNi, InBiNi, InSnNi, GaBiNi, and GaSnNi.\nSubsequently, these LACs were subjected to catalytic performance testing. We found that the space-time\nyield (STY) of light olefins of the quaternary GaInNiSn LAC exceeded the average STY of light olefins of the\nternary LACs by 75.4%. These results demonstrate that the increase in the S induces a significant\nif-config\nimprovement in the STY of light olefins. Specifically, the STY of light olefins during the depolymerization\nof polypropylene plastic using ternary LACs ranged from 94.5 to 123.3 mmol g \\minus1 h\\minus1. In comparison, the\ncat\n-16-\nSTY of the quaternary GaInNiSn LAC reached 181.5 mmol g \\minus1 h\\minus1, representing a 75.4% increase over\ncat\nthe average STY of the ternary LACs (Response Fig. 5). Moreover, the S of ternary LACs ranged\nif-config\nbetween 4.92 and 5.88 J mol\\minus1 K\\minus1, while the S of the quaternary GaInNiSn LAC reached 8.55 J mol\\minus1\nif-config\nK\\minus1, representing a 60.4% increase over the average S of the ternary LACs (Response Table 2). The\nif-config\nabove results imply that as the S increases, the improvement in STY of quaternary GaInNiSn LAC is\nif-config\nquite significant.\nIn summary, the interfacial configurational entropy tuning strategy, dominated by element composition,\nnot only achieves interfacial enrichment of active sites in liquid alloys but also facilitates electron transfer,\nthereby enabling high catalytic performance.\nResponse Fig. 5. Comparison of depolymerization performance between ternary and quaternary liquid\nalloy catalysts (all active metals being Ni). The dashed line denotes the average STY of the ternary LACs\n(103.45 mmol g \\minus1 h\\minus1). Reaction conditions: 1.00 g of polypropylene plastic, 1.95 g of different LACs\ncat\n(SnBiNi, InBiNi, InSnNi, GaBiNi, GaSnNi, GaInNi, and GaInNiSn), N feed gas at a flow rate of 4 mL min\\text{--}1,\n2\nand 500 °C for 3 min.\nResponse Table 1. Comparison of the conductivity of the GaInNi LELAC and the GaInNiSn MELAC\nSample Resistivity (Ω·cm) Conductivity (Ω\\minus1·cm\\minus1)\nGaInNi 2.83 × 10\\minus5 3.53 × 104\n-17-\nGaInNiSn 2.82 × 10\\minus5 3.55 × 104\nResponse Table 2. Comparison of the S of liquid alloys in this work\nif-config\nSample Element x (mol%) S (J mol\\minus1 K\\minus1) Evaluation\ni if-config\nSn 79.14\nSnBiNi Bi 18.25 4.92 Low entropy\nNi 2.61\nIn 80.51\nInBiNi Bi 15.32 4.94 Low entropy\nNi 4.17\nIn 75.35\nInSnNi Sn 20.08 5.61 Low entropy\nNi 4.57\nGa 77.88\nGaBiNi Bi 18.74 5.16 Low entropy\nNi 3.38\nGa 76.96\nGaSnNi Sn 18.21 5.45 Low entropy\nNi 4.83\nGa 61.43\nGaInNi In 38.71 5.88 Low entropy\nNi 0.86\nGa 62.52\nIn 20.90\nGaInNiSn 8.55 Medium entropy\nNi 8.74\nSn 7.84\nThe data used for calculating the S of the alloys (SnBiNi, InBiNi, InSnNi, GaBiNi, GaSnNi, GaInNi, and\nif-config\nGaInNiSn) were all derived from XPS spectra. The alloys were synthesised with well-defined mass ratios:\nSnBiNi (Sn:Bi:Ni = 6:3:1), InBiNi (In:Bi:Ni = 6:3:1), InSnNi (In:Sn:Ni = 6:3:1), GaBiNi (Ga:Bi:Ni = 6:3:1),\nGaSnNi (Ga:Sn:Ni = 6:3:1), GaInNi (Ga:In:Ni = 6:3:1), and GaInNiSn (Ga:In:Ni:Sn = 60:30:6:4).\n-18-\nWe have revised the relevant description in the Introduction of the manuscript (Page 4, Line 74\\minus76;\nPage 5, Line 79\\minus80):\nIn stark contrast to the binary or ternary liquid alloy catalysts, the increase in the S of the GaInNiSn\nif-config\nMELAC attenuates interfacial Gibbs free energy (Eq. S9), thereby modulating Ni active sites and\npromoting their enrichment on the Ga interface.\nMechanistic insights suggest that Sn electronically modifies Ni to form Niδ\\minus–Snδ+ sites at the GaIn interface,\nactivating C\\text{--}H bonds for selective depolymerization via \\beta-scission.\nWe have revised the relevant description in Section 2.1 of the manuscript (Page 5, Line 96\\minus98 and Line\n103\\minus106; Page 6, Line 113\\minus115):\nContact angle tests (Fig. S3) exhibited that Sn incorporation remarkably reduced the surface tension of\nGaIn alloys, thus providing a large solid-liquid contact area for plastic depolymerization.\nIn stark contrast to the binary or ternary LAC, the Sift-config of quaternary GaInNiSn was remarkably\ngreater than those of low-entropy liquid alloys (LELAC) (Fig. 2c). This attribute endows the GaInNiSn\nMELAC with low interfacial Gibbs free energy (Supplementary Note 1), thus facilitating interfacial\nenrichment and reconstruction of active sites.\nSince the depolymerization process by LAC is a typical solid-liquid heterogeneous catalysis reaction, the\nNi surface enrichment in the GaInNiSn MELAC contributes to enlarging the active specific surface area,\nleading to superior performance in the bond cleavage process.\nWe have revised the relevant description in Section 2.2 of the manuscript (Page 10, Line 224\\minus225):\nThe negatively charged Ni site in the GaInNiSn MELAC leads to strong H adsorption (Fig. S26), reducing\nC\\text{--}H activation barriers and boosting subsequent \\beta-scission.\n-19-\nFig. 3. Depolymerization performance of the GaInNiSn MELAC. (a) Comparison of depolymerization\nperformance between ternary and quaternary liquid alloy catalysts (all active metals being Ni). The\ndashed line denotes the average STY of the ternary LACs (105.35 mmol g \\minus1 h\\minus1). Reaction conditions:\ncat\n1.0 g of polypropylene plastic, 1.95 g of different LACs (SnBiNi, InBiNi, InSnNi, GaBiNi, GaSnNi, GaInNi,\nand GaInNiSn), N feed gas at a flow rate of 4 mL min\\text{--}1, and 500 °C for 3 min. (b) Comparison of the\n2\nperformance of different depolymerization and recycling technologies, including the conversion of plastic,\nthe selectivity of light olefins, and the space-time yield of light olefins2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15. (c)\n-20-\nSpace-time yield of light olefins and selectivity of gaseous products during depolymerization of diverse\npolyolefin plastics. Reaction conditions: 1.0 g of reactants (PP, LDPE, HDPE, PS, POE, and SBS), 1.95 g of\nGaInNiSn MELAC, N feed gas at a flow rate of 4 mL min\\text{--}1, and 500 °C for 3 min. PP+LDPE, PP+HDPE,\ncorresponding polymer. Mix denotes the equal mass ratio mixture of these six reactants. (d) Space-time\nyield of light olefins and selectivity of gaseous products during depolymerization of real-world plastic\nwaste. Reaction conditions: 1.0 g of reactants (food packaging bags, take-away containers, drinking\nwater bottle caps, milk bottles, beverage straws, toothpaste tubes, foam boxes, reagent buckets, and\nmedical ziplock bags), 1.95 g of GaInNiSn MELAC, N feed gas at a flow rate of 4 mL min\\text{--}1, and 500 °C for\n2\n3 min. Mix denotes the equal mass ratio mixture of these nine reactants.\nWe have updated the Supplementary Note 3 and Tables S1,S3 in the supporting information:\nWe measured the resistivity and conductivity of the GaInNi LELAC and the GaInNiSn MELAC using the Hall\neffect measurement, as shown in Table S3. The conductivities of the GaInNi LELAC and the GaInNiSn\nMELAC were of the same order of magnitude, at 3.53 × 104 Ω\\minus1·cm\\minus1 and 3.55 × 104 Ω\\minus1·cm\\minus1, respectively,\ndiffering by only 0.57%. Therefore, the GaInNi LELAC and the GaInNiSn MELAC exhibit nearly identical\nmagneto-thermal conversion efficiency, as the receptor of induction heating. In contrast, insulating\nplastic particles are not capable of responding to RF energy. As shown in Video 1, the GaInNiSn MELAC\ndoes not form small metal droplets due to the high u . Consequently, we attribute the enhanced catalytic\nmf\nperformance of the GaInNiSn MELAC to our proposed entropy engineering strategy. Specifically, we\nincreased the interfacial configurational entropy (S ) of the liquid alloy by introducing the regulatory\nif-config\nmetal Sn. In stark contrast to the binary or ternary liquid alloy catalysts, the increase in the S of the\nif-config\nGaInNiSn MELAC attenuates interfacial Gibbs free energy, thereby modulating Ni active sites and\npromoting their enrichment on the Ga interface. Furthermore, Sn electronically modifies Ni to form Niδ\\minus–\nSnδ+ sites at the GaIn interface, activating C\\text{--}H bonds for selective depolymerization via \\beta-scission.\nMeanwhile, the lower surface tension of the GaInNiSn MELAC provides a larger solid-liquid contact area\nfor plastic depolymerization, which is one reason for its superior catalytic performance.\nTo further underscore the proposed strategy for designing LAC catalysts, we synthesized other ternary\nLACs with an identical active metal content (10wt% Ni): SnBiNi, InBiNi, InSnNi, GaBiNi, and GaSnNi.\n-21-\nSubsequently, these LACs were subjected to catalytic performance testing. We found that the space-time\nyield (STY) of light olefins of the quaternary GaInNiSn LAC exceeded the average STY of light olefins of the\nternary LACs by 75.4%. These results demonstrate that the increase in the S induces a significant\nif-config\nimprovement in the STY of light olefins. Specifically, the STY of light olefins during the depolymerization\nof polypropylene plastic using ternary LACs ranged from 94.5 to 123.3 mmol g \\minus1 h\\minus1. In comparison, the\ncat\nSTY of the quaternary GaInNiSn LAC reached 181.5 mmol g \\minus1 h\\minus1, representing a 75.4% increase over\ncat\nthe average STY of the ternary LACs (Fig. 3a). Moreover, the S of ternary LACs ranged between 4.92\nif-config\nand 5.88 J mol\\minus1 K\\minus1, while the S of the quaternary GaInNiSn LAC reached 8.55 J mol\\minus1 K\\minus1,\nif-config\nrepresenting a 60.4% increase over the average S of the ternary LACs (Table S1). The above results\nif-config\nimply that as the S increases, the improvement in STY of quaternary GaInNiSn LAC is quite significant.\nif-config\nIn summary, the interfacial configurational entropy tuning strategy, dominated by element composition,\nnot only achieves interfacial enrichment of active sites in liquid alloys but also facilitates electron transfer,\nthereby enabling high catalytic performance.\nTable S1. Comparison of the S of liquid alloys between this work and previous literature\nif-config\nSample Element x (mol%) S (J mol\\minus1 K\\minus1) Evaluation\ni if-config\nGaNi Ga 99.43\n0.29 Low entropy\n(This work) Ni 0.57\nGa 99.41\nGaSn16 0.30 Low entropy\nSn 0.59\nGa 98.93\nGaZn16 0.49 Low entropy\nZn 1.07\nGa 98.58\nGaMg16 0.62 Low entropy\nMg 1.42\nGa 97.81\nGaCu17, 18 0.87 Low entropy\nCu 2.19\nInNi In 93.91\n1.91 Low entropy\n(This work) Ni 6.09\nGa 92.60\nGaAl16 2.20 Low entropy\nAl 7.40\nSnNi Sn 87.38 3.25 Low entropy\n-22-\n(This work) Ni 12.62\nGa 83.54\nEGaIn19, 20, 21 3.71 Low entropy\nIn 16.46\nPb 83.00\nPbNi22 3.79 Low entropy\nNi 17.00\nGaIn Ga 76.70\n4.51 Low entropy\n(This work) In 23.30\nBi 73.00\nBiNi22, 23 4.86 Low entropy\nNi 27.00\nSn 89.86\nSnInCu24 In 9.29 2.97 Low entropy\nCu 0.85\nBi 89.75\nBiNiMo23 Ni 7.63 3.23 Low entropy\nMo 2.62\nSn 79.14\nSnBiNi\nBi 18.25 4.92 Low entropy\n(This work)\nNi 2.61\nIn 80.51\nInBiNi\nBi 15.32 4.94 Low entropy\n(This work)\nNi 4.17\nGa 77.90\nGaSnCu18 Sn 19.61 5.03 Low entropy\nCu 2.49\nGa 77.39\nGaInCu18 In 20.13 5.11 Low entropy\nCu 2.48\nGa 77.88\nGaBiNi\nBi 18.74 5.16 Low entropy\n(This work)\nNi 3.38\nGa 78.36\nEGaInSn18, 19, 21 5.40 Low entropy\nIn 14.93\n-23-\nSn 6.72\nGa 76.96\nGaSnNi\nSn 18.21 5.45 Low entropy\n(This work)\nNi 4.83\nGa 61.43\nGaInNi\nIn 38.71 5.88 Low entropy\n(This work)\nNi 0.86\nIn 75.35\nInSnNi\nSn 20.08 5.61 Low entropy\n(This work)\nNi 4.57\nGa 71.35\nGaInSn\nIn 21.67 6.31 Low entropy\n(This work)\nSn 6.98\nGa 62.52\nIn 20.90\nGaInNiSn\n8.55 Medium entropy\n(This work, 25 °C)\nNi 8.74\nSn 7.84\nGa 55.68\nIn 20.14\nGaInNiSn\n9.62 Medium entropy\n(This work, 500 °C)\nNi 12.75\nSn 11.43\nThe data used for calculating the S of the alloys (GaNi, InNi, SnNi, SnBiNi, InBiNi, GaBiNi, GaSnNi,\nif-config\nGaInNi, InSnNi, and GaInNiSn) were all derived from XPS spectra. The alloys were synthesized with well-\ndefined mass ratios: GaNi (Ga:Ni = 9:1), InNi (In:Ni = 9:1), SnNi (Sn:Ni = 9:1), SnBiNi (Sn:Bi:Ni = 6:3:1),\nInBiNi (In:Bi:Ni = 6:3:1), GaBiNi (Ga:Bi:Ni = 6:3:1), GaSnNi (Ga:Sn:Ni = 6:3:1), GaInNi (Ga:In:Ni = 6:3:1),\nInSnNi (In:Sn:Ni = 6:3:1), and GaInNiSn (Ga:In:Ni:Sn = 60:30:6:4).\nTable S3. Comparison of the conductivity of the GaInNi LELAC and the GaInNiSn MELAC\nSample Resistivity (Ω·cm) Conductivity (Ω\\minus1·cm\\minus1)\nGaInNi 2.83 × 10\\minus5 3.53 × 104\n-24-\nGaInNiSn 2.82 × 10\\minus5 3.55 × 104\nACTION: Manuscript and Supporting Information amended\n-25-\nReferences\n1. Karl J, Pröll T. Steam gasification of biomass in dual fluidized bed gasifiers: A review. Renew Sust Energ Rev\n98, 64-78 (2018).\n2. Lin YH, Sharratt PN, Garforth AA, Dwyer J. Catalytic conversion of polyolefins to chemicals and fuels over\nvarious cracking catalysts. Energy & Fuels 12, 767-774 (1998).\n3. Lovás P, Hudec P, Jambor B, Hájeková E, Hornácek M. 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Decision letter