Green Energy&Environment

2025 Vol. 10, No. 11

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Special Topic Innovations in Metal-Organic Frameworks_Review articles
Special Topic Innovations in Metal-Organic Frameworks_Research papers
Contributed Papers_Review articles
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Special Topic Innovations in Metal-Organic Frameworks_Review articles

Tailoring the architecture of metal-organic frameworks: Precision etching for engineered defects and surfaces

Yunfei Jiang, Ziyi Zhang, Yongjian Du, Jinwen Jiao, Ya Bian, Di Cai, Houchao Shan

2025, 10(11): 2107-2142. doi: 10.1016/j.gee.2025.09.006

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Metal-organic frameworks (MOFs) have emerged as promising materials owing to their high surface areas, tunable pore sizes, and diverse functionalities. However, their practical deployment is frequently hindered by intrinsic microporosity and structural fragility. In this review, we systematically analyze recent advancements in MOF etching techniques, which strategically modify framework architectures to enhance mass transport, expose active sites, and improve stability. The discussion encompasses a range of methods—including acid, base, ion, solvent, steam, selective, in-situ, pyrolysis, and physical etching—with emphasis on the underlying mechanisms that govern the formation of hierarchical pore structures, defect engineering, and heterojunction formation. Notably, etching approaches facilitate precise control over crystal morphology and surface chemistry, thereby optimizing MOF performance in catalysis, electrocatalysis, photocatalysis, adsorption, energy storage, sensing, and biomedical applications. We also outline challenges such as etchant toxicity, over-etching risks, and scalability, while highlighting emerging strategies and computational simulations to refine the etching process. Ultimately, this review underscores the transformative impact of etching on MOF properties, paving the way for the design of next-generation multifunctional materials that address critical issues in environmental remediation, energy conversion, and beyond.

Special Topic Innovations in Metal-Organic Frameworks_Research papers

Computational screening of covalent organic frameworks for He purification with adsorption or membrane separation

Zenan Shi, Lijun Liao, Shujun Peng, Yanying Wei, Libo Li

2025, 10(11): 2143-2155. doi: 10.1016/j.gee.2025.09.002

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Separating He from CH₄ or N₂ is crucial for natural gas He extraction, a prevailing industrial approach. Herein, molecular simulation and machine learning (ML) were combined to screen 801 experimentally synthesized COFs for He/CH₄ and He/N₂ separation, either by means of adsorption or membrane separation. Top 10 COFs for 4 different gas separation purposes (CH₄/He or N₂/He separation with either adsorption or membrane) were identified respectively. The highest adsorption performance score (APS^mix, defined as the product of working capacity and adsorption selectivity for mixture gas) reached 447.88 mol/kg and 49.45 mol/kg for CH₄/He and N₂/He, with corresponding adsorption selectivity of 115.56 and 30.33. He permeabilities of 1.5 × 10⁶ or 1.2 × 10⁶ Barrer were achieved for equimolar He/CH₄ or He/N₂ mixture gas separations, accompanied by permselectivity of 5.47 and 11.80 well surpassing 2008 Robeson's upper bound. Best performing COFs for adsorption separation are 3D COFs with pore diameter below 0.8 nm while those for membrane separation are 2D COFs with large pores. Additionally, ML models were developed to predict separation performance, with key descriptors identified. The mechanism for how COFs' structure affects their separation performance was also revealed.

High-efficiency capacitive deionization: Freestanding carbon electrodes derived from fungal hyphae with in-situ oriented MOF growth

Jiao Chen, Kuichang Zuo, Jiajin Liang, Gang Wang, Lin Lin, Xiao-yan Li

2025, 10(11): 2156-2166. doi: 10.1016/j.gee.2025.09.009

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High-performance electrode materials are critical for the development of the capacitive deionization (CDI) technology for efficient water desalination. In this study, binder-free porous carbon electrodes were successfully prepared from the fungal hyphae sheet with the formation and growth of metal-organic framework (MOF) crystals on the surface of hyphal fibers. The continuous fungal fibrous structure with abundant surface functional groups provided an ideal supporting substrate for in-situ oriented MOF growth. The MOF-fungal hyphae derived carbon (MOF-Fhy-C) exhibited an excellent property for CDI application, such as a large accessible surface area, excellent electrical conductivity, high porosity and hydrophilicity. The MOF-Fhy-C electrode achieved an outstanding CDI performance with a salt adsorption capacity of 40.8 mg g^-¹ and an average salt adsorption rate of 1.4 mg g^-1 min^-1 for treating 10 mmol L^-¹ NaCl solution at a cell voltage of 1.2 V, which are considerably higher than most of carbon-based electrodes reported in the literature. This research presents an effective strategy for fabricating freestanding CDI electrodes from fungal materials with MOF for high-performance desalination.

Oriented superhydrophobic bimetallic MOF composite membrane for efficient ethanol-water separation

Fengkai Wang, Yushan Zhang, Yiming Zhong, Mengxin Shen, Hao Sun, Jie Li, Naixin Wang, Hong Meng, Quan-Fu An

2025, 10(11): 2167-2176. doi: 10.1016/j.gee.2025.09.012

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Extracting ethanol from aqueous solutions is important but challenging in industry. Pervaporation membranes show great promise for separating ethanol from water, with the design of their structure being crucial for enhancing performance. In this study, we developed an oriented bimetallic metal-organic framework (MOF) membrane, designated as ZIF-CoZn, for the pervaporation separation of ethanol from water. During crystal growth, bimetallic salts provide specific nucleation sites, and the competitive coordination between Co and Zn ions shifts the energetically favorable (100) plane to the (211) plane. This orientation enables precise molecular-level control over hydrophobic ligand arrangement, effectively repelling water molecules. Meanwhile, bimetallic competition enlarges pore sizes, facilitating ethanol permeation. When compared to single-metal MOF membranes made of cobalt or zinc, the separation factor of the ZIF-CoZn membrane for ethanol/water mixtures increased by 127% and 160%, respectively. Benefiting from the high roughness and increased exposure of hydrophobic ligands due to the preferential (211) orientation, ZIF-CoZn exhibits superhydrophobicity after vinyl-polydimethylsiloxane coating. The oriented ZIF-CoZn membrane was also scaled up to an area of 1 m². This work provides valuable insights into optimizing MOF membrane structure and lays the foundation for its promotion and application in the industry.

Highly selective electrocatalytic CO₂ reduction to liquid C₂ products by means of a tandem catalytic system

Nan Wang, Yuan Zhang, Xiaoxin Tian, Mingming Sun, Lei Yuan, Huiyong Wang, Jianji Wang

2025, 10(11): 2177-2186. doi: 10.1016/j.gee.2025.06.007

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Electrocatalytic CO₂ reduction for the synthesis of high value-added multi-carbon (C₂₊) products is a promising strategy to achieve energy storage and carbon neutrality. However, to acquire high selectivity of C₂₊ products remains a challenge. Herein, Ag NCs@Ag-MOF with highly dispersed Ag nanoclusters (NCs) and Cu-O₂N₂-COF with Cu-O₂N₂ active sites were designed, synthesized and then coupled for the conversion of CO₂ to liquid C₂ products (ethanol and acetate). Faradaic efficiency (FE) of the liquid C₂ products was 90.9% at -0.98 V (vs. RHE), which is 1.9 times that of Cu-O₂N₂-COF in direct CO₂ electroreduction and the highest liquid C₂ products selectivity reported so far. The current density reached 324.8 mA·cm^-2 at -1.2 V (vs. RHE). In situ infrared spectroscopy and density functional theory calculations showed that the tandem catalytic system significantly enhanced the accumulation of *CO on the catalyst and promoted *CO-*CO coupling, thus significantly improving the selectivity of liquid C₂ products.

Converting waste polyimide into porous carbon nanofiber for all-weather freshwater and hydroelectricity generation

Lijie Liu, Huajian Liu, Huiyue Wang, Kuankuan Liu, Guixin Hu, Yan She, Xueying Wen, Hangyuan Du, Lingling Feng, Jiang Gong

2025, 10(11): 2187-2200. doi: 10.1016/j.gee.2025.06.004

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The dual system capable of solar-driven interfacial steam production and all-weather hydropower generation is emerging as a potential way to alleviate freshwater shortage and energy crisis. However, the intrinsic mechanism of hydroelectricity generation powered by the interaction between seawater and material structure is vague, and it remains challenging to develop dual-functional evaporators with high photothermal conversion efficiency and ionic selectivity. Herein, an all-weather dual-function evaporator based on porous carbon fiber-like (PCF) is acquired through the pyrolysis of barium-based metal-organic framework (Ba-BTEC), which is originated from waste polyimide. The PCF-based evaporator/device exhibits a high steam generation rate of 2.93 kg m^-2 h^-1 in seawater under 1 kW m^-2 irradiation, along with the notable open-circuit voltage of 0.32 V, owing to the good light absorption ability, optimal wettability, and suitable aperture size. Moreover, molecular dynamics simulation result reveals that Na⁺ tends to migrate rapidly within the nanoporous channels of PCF, owing to a strong affinity between oxygen-containing functional group and water molecules. This work not only proposes an eco-friendly strategy for constructing low-cost full-time freshwater-hydroelectric co-generation device, but also contributes to the understanding of evaporation-driven energy harvesting technology.

Contributed Papers_Review articles

Advanced batteries for sustainable energy storage

Wenbin Li, Changtai Zhao, Chang Yu, Yan Yu, Jia-Qi Huang, Yingying Lu, Hao Jiang, Shuai Gu, Zhouguang Lu, Xue Yang, Le Yu, Yuan Ren, Siqi Shi, Weihua Chen

2025, 10(11): 2201-2258. doi: 10.1016/j.gee.2025.07.009

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The increasingly severe energy crisis and environmental issues have raised higher requirements for grid-scale energy storage systems. Rechargeable batteries have enormous development prospects due to their flexibility and environmental protection. However, the traditional organic liquid-based batteries cannot meet our needs for future advanced batteries in terms of safety, energy density, and stability under extreme working conditions. In this case, we comprehensively summarize various advanced battery technologies to overcome the above problems. Firstly, we highlight the advantage of solid-state batteries compared to liquid electrolytes. Specifically, we focus on the advantages and challenges of solid-state lithium/sodium batteries and other types of solid-state batteries associated with the electrodes, solid electrolytes and the electrode/electrolyte interphase. Secondly, we discuss the environmentally friendly and safe liquid-state battery and its application prospect. Thirdly, the battery improvement strategy has been proposed to enhance the application of batteries under extreme conditions. Subsequently, we emphasize the importance of theoretical calculations and AI technology in promoting the development of battery technology. Finally, the current challenges and future directions of battery technology are summarized. The combination of in-depth failure mechanism analysis, advanced characterization techniques, economic commercialization and machine learning enables the rapid development of advanced battery technology for sustainable energy storage.

Preparation, microstructure and corrosion resistance of novel anode materials based on magnesium-air batteries

Qi Sun, Shaohua Luo, Jun Cong, Xin Yan, Qiuyue Liu, Shengxue Yan, Pengwei Li, Xiaoping Lin

2025, 10(11): 2259-2278. doi: 10.1016/j.gee.2025.05.006

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Magnesium-air (Mg-air) batteries have emerged as a promising sustainable energy storage technology, offering exceptional theoretical energy density, low cost, and environmental compatibility. Despite these advantages, their development remains largely confined to experimental phase. A critical barrier to commercialization is the poor corrosion resistance of the anode resulting in low anodic efficiency. This article presents a comprehensive review of strategies aimed at improving the utilization efficiency of Mg anodes, with a particular focus on addressing corrosion issues from a microstructural standpoint. Firstly, the principle of Mg-air batteries has been outlined and the corrosion behavior has been discussed. The review then delves into a variety of representative anode materials. Special attention is given to innovative material designs that mitigate the challenges typically encountered by Mg-air batteries. Finally, the paper provides an outlook on future research directions, identifying critical technological barriers and highlighting areas that warrant further investigation. By offering a detailed analysis of material structures, this article aims to contribute valuable insights for advancing the development of high-performance Mg-air batteries.

Contributed Papers_Research papers

CO₂ and ethylene vinyl acetate co-modification of solid waste-based filling materials: An integrated approach for carbon capture and recycling

Dedan Duan, Huiping Song, Xiaojuan Du, Quan An, Huaigang Cheng, Fangqin Cheng, Junpeng Xie, Yongzhen Yang

2025, 10(11): 2279-2296. doi: 10.1016/j.gee.2025.05.005

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To improve the rigidity and flexibility of conventional grouting materials, one visionary approach is to replace Portland cement with a composite cementitious system containing circulating fluidized bed fly ash (CFBFA) and calcium carbide slag (CS), while adding ethylene-vinyl acetate (EVA) copolymer and CO₂ as modifiers to enhance its properties. In this research, CFBFA and CS assumed the role of cementitious constituents, with EVA and CO₂ serving as the modifying agent. A comprehensive exploration of the mechanism underlying the CO₂ + EVA modified composite cementitious system was undertaken, delving into the differences of its compressive, bending, and flexural strengths. The addition of CO₂ further improved the flexibility and rigidity of the materials and effectively improve the material's microstructure. It was worth noting that when CO₂ + EVA co-modified CFBFA-CS composite cementitious materials, the flexibility and rigidity of the cementitious materials were significantly enhanced, and the bending strength, flexural strength and compressive strength were significantly increased by 48.76%, 166.7% and 40.56%, respectively, and the 28 d density was reduced by 6.91%. These results provided a theoretical basis for the realization of avant-garde cementitious materials with functional properties.

Robust ambient-stable 2D heterostructure of copper oxides intercalating black phosphorus for flame retardancy and catalytic removal of carbon monoxide

Xiaoyang Yu, Huan Li, Xuyang Miao, Ning Kang, Wenbin Yao, Mingjun Xu

2025, 10(11): 2297-2310. doi: 10.1016/j.gee.2025.04.009

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Two-dimensional black phosphorus (2D BP) utilized in flame retardant applications frequently encounters significant challenges, including inadequate ambient stability and elevated carbon monoxide (CO) release rates. To mitigate these issues, an effective approach was proposed for the fabrication of 2D heterostructures comprising copper oxide intercalated with BP in this work. This methodology takes into account both thermodynamic and kinetic factors, resulting in substantial enhancements in the ambient stability of BP and the catalytic performance for CO elimination, achieved through the synergistic interactions between 2D BP and copper oxide, all while preserving the structural integrity of 2D BP. The incorporation of gelatin and kosmotropic anions facilitated the efficient adhesion of the multifunctional heterostructures to the flammable flexible polyurethane foam (FPUF), which not only scavenged free radicals in the gas phase but also catalyzed the formation of a dense carbon layer in the condensed phase. Kosmotropic anions induce a salting-out effect that fosters the development of a chain bundle, a hydrophobic interaction domain, and a potential microphase separation region within the gelatin chains, leading to a marked improvement in the mechanical strength of the heterostructure coatings. The modified FPUF exhibited a high limiting oxygen index (LOI) value of 34%, alongside significantly improved flame resistance: the peak CO release rate was reduced by 78%, the peak heat release rate decreased by 57%, and the fire performance index (FPI) was increased by 40 times compared to untreated FPUF. The 2D heterostructure coatings demonstrated better CO catalytic removal performance relative to previously reported flame retardant products. This research offers a promising design principle for the development of next-generation high-performance flame retardant coatings aimed at enhancing fire protection.

Single sodium atoms anchored on N-doped porous carbon: Solid strongly basic catalysts with uncommon activity and stability

Sai Liu, Xiang-Bin Shao, Zhi-Wei Xing, Xing-Ru Song, Kai Zhang, Yang Wang, Peng Tan, Lin-Bing Sun

2025, 10(11): 2311-2319. doi: 10.1016/j.gee.2024.12.003

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Solid strong base catalysts have high potentials in a variety of reactions due to the advantages of negligible corrosion, easy separation, and high efficiency. However, two issues hinder the applications of such catalysts seriously, namely aggregation of basic sites and leaching of active species during reactions. The development of solid strong base catalysts with active sites that are highly dispersed and stable remains a pronounced challenge. In this work, we employed a two-step reduction strategy to anchor Na single atoms on nitrogen-doped porous carbon (NPC) support, producing a high-performance solid strongly basic catalyst named as Na₁/NPC. The alkali precursor NaNO₃ was converted to Na₂O on NPC at 400 °C, in which conventional solid base catalyst Na₂O/NPC was generated. Upon heat treatment at 850 °C, Na₂O was further reduced to Na single atoms anchored on NPC, creating Na₁/NPC. Experimental studies and theoretical calculations show that Na is structurally embedded on the support in penta-coordinated configuration (Na-C₃N₂). The synergistic effect of highly dispersed Na atoms and nitrogen doping results in uncommon catalytic activity and stability. In transesterification between methanol and ethylene carbonate to produce dimethyl carbonate (DMC), the yield of DMC reaches 48.4% over Na₁/NPC, corresponding to a turnover frequency (TOF) of 129.4 h^-1, which is far beyond the conventional counterpart Na₂O/NPC (63.3 h^-1) and various reported solid base catalysts. The catalytic activity of Na₁/NPC almost keeps constant during five cycles, while 87% of activity is lost for Na₂O/NPC due to the leaching of basic sites. This work might offer new ideas for the development of efficient single-atom solid strong base catalysts with high efficiency.