Green Energy&Environment

Engineering of copper sulfide-based nanomaterials for thermoelectric application

Binqi He, Kai Zhang, Maiyong Zhu

2025, 10(4): 619-688. doi: 10.1016/j.gee.2024.11.010

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In the context of diminishing energy resources and worsening greenhouse effect, thermoelectric materials have great potential for sustainable development due to their green and environmentally friendly characteristics. Among inorganic thermoelectric materials, copper sulfide compounds have greater potential than others due to their abundant element reserves on Earth, lower usage costs, non-toxicity, and good biocompatibility. Compared to organic thermoelectric materials, the "phonon liquid-electron crystal" (PLEC) feature of copper sulfide compounds makes them have stronger thermoelectric performance. This review summarizes the latest research progress in the synthesis methods and thermoelectric modification strategies of copper sulfide compounds. It first explains the importance of the solid-phase method in the manufacture of thermoelectric devices, and then focuses on the great potential of nanoscale synthesis technology based on liquid-phase method in the preparation of thermoelectric materials. Finally, it systematically discusses several strategies for regulating the thermoelectric performance of copper sulfide compounds, including adjusting the chemical proportion of Cu_2-xS and introducing element doping to regulate the crystal structure, phase composition, chemical composition, band structure, and nanoscale microstructure of copper sulfide compounds, and directly affecting ZT value by adjusting conductivity and thermal conductivity. In addition, it discusses composite engineering based on copper sulfide compounds, including inorganic, organic, and metal compounds, and discusses tri-component compounds derived from sulfide copper. Finally, it discusses the main challenges and prospects of the development of copper sulfide-based thermoelectric materials, hoping that this review will promote the development of copper sulfide-based thermoelectric materials.

Interfacial regulation for zinc metal anode of aqueous zinc-ion battery

Jing Zhu, Xumeng Ge, Zhi Peng, Liang Pan, Ziyu Peng, Yingqiao Jiang, Wei Meng, Zekun Zhang, Ningning Zhao, Bin Li, Lei Dai, Ling Wang, Zhangxing He

2025, 10(4): 689-708. doi: 10.1016/j.gee.2024.11.001

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Aqueous zinc-ion batteries (AZIBs) have attracted significant attention due to their high energy density, low cost, high efficiency, and environmental friendliness. Nevertheless, the development of AZIBs has been significantly hindered by the unavoidable issues with zinc dendrites and the side reactions of the anode. The strategies for stable and controllable interfacial regulation have recently made rapid progress, due to their dual function of improving zinc ion transport dynamics and preventing direct contact of zinc with electrolytes. Therefore, it's imperative to conduct a comprehensive summary of the interfacial regulation of zinc anodes and to engage in in-depth research into the underlying mechanisms. Subsequently, the interfacial regulation was classified based on battery structure, including anode coating strategy, electrolyte engineering, and separator optimization. Eventually, the current limitations of interfacial regulation and a deep outlook on AZIBs interface engineering are summarized.

Progress in the construction strategy of noble metal active sites for zeolite-based PNA and VOCs catalysts

Yuan Yao, Haodan Cheng, Guocai Zhong, Xiaolong Tang, Honghong Yi, Shunzheng Zhao, Fengyu Gao, Qingjun Yu

2025, 10(4): 709-732. doi: 10.1016/j.gee.2024.06.001

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Zeolite-loaded noble metal catalysts have demonstrated excellent performance in addressing cold-start automotive exhaust NO_x emissions and catalytic oxidation of VOCs applications. Pd and Pt are the most commonly used active metals in PNA and VOC catalysts, respectively. However, despite the same metal/zeolite composition, the efficient active sites for PNA and VOC catalysts have been viewed as mainly Pd²⁺ and Pt⁰, respectively, both of which are different from each other. As a result, various methods need to be applied to dope Pd and Pt in zeolitic support respectively for different usages. No matter which type of metal species is needed, the common requirement for both PNA and VOC catalysts is that the metal species should be highly dispersed in zeolite support and stay stable. The purpose of this paper is to review the progress of synthetic means of zeolite-coated noble metals (Pd, Pt, etc.) as effective PNA or VOC catalysts. To give a better understanding of the relationship between efficient metal species and the introduced methods, the species that contributed to the NO_x adsorption (PNA) and VOCs deep catalytic oxidation were first summarized and compared. Then, based on the above discussion, the detailed construction strategies for different active sites in PNA and VOC catalysts, respectively, were elaborated in terms of synthetic routes, precursor selection, and zeolite carrier requirements. It is hoped that this will contribute to a better understanding of noble metal adsorption/catalysis in zeolites and provide promising strategies for the design of adsorption/catalysts with high activity, selectivity and stability.

Heterogeneous iron-based catalysts for a sustainable photoinduced nitrogen fixation

Amalia M. Grigoras, Federica Valentini, Loredana Latterini, Luigi Vaccaro

2025, 10(4): 733-755. doi: 10.1016/j.gee.2024.07.003

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Ammonia is nowadays one of the most important commodities chemicals intensively produced at about 175 million tons per year, contributing to 1.8% of the global energy demand. The constantly increasing NH₃ demand also paralleleds by the high CO₂ emissions associated with its production. Therefore, decarbonizing NH₃ synthesis is one of the most urgent contemporary challenges. Taking inspiration from Nature, solar-driven nitrogen fixation under mild conditions is one of the most promising yet challenging alternatives to classic methods. In this review, we focused our attention on the photocatalytic methods for the synthesis of ammonia; in particular, we concentrated on stable and recyclable heterogeneous Fe-based photocatalysts for producing NH₃. Indeed, recoverable and widely abundant and low-cost iron catalysts may represent a very promising tool for future sustainable access to this largely desired chemical target. After an overview of the pioneering works on Fe-driven nitrogen photofixation, the recent strategies on the use of Fe are herein reported. Compared with pristine photocatalysts, adding Fe as dopant or composite and heterojunction highly enhances the photocatalytic performances, opening the way to sustainable and low-cost nitrogen production.

Engineering crystal plane of NiCo₂O₄ to regulate oxygen vacancies and acid sites for alkali-free oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid

Hengli Qian, keyuan Zhang, Yongchuo He, Qidong Hou, Chao Xie, Ruite Lai, Guanjie Yu, Tianliang Xia, Xinyu Bai, Haijiao Xie, Meiting Ju

2025, 10(4): 756-765. doi: 10.1016/j.gee.2024.05.002

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The catalytic oxidation of HMF involves a cascading reaction with multiple intermediate products, making it crucial to enhance the oriented adsorption capacity of specific functional groups for accelerating the entire process. To achieve the efficient selective oxidation of HMF to FDCA, a series of NiCo₂O₄ catalysts with different morphologies, such as flaky, echinoids, pompon and corolla, were prepared and characterized by XRD, SEM, TEM, BET, XPS, and FTIR. Among the four catalysts, flaky NiCo₂O₄ exhibited the most excellent catalytic activity and stability, with a FDCA yield of 60.1% within 12 h at 80 ℃ without alkali participation. The excellent performance of flaky NiCo₂O₄ catalyst is attributed to the oxygen vacancies and acid sites generated by the exposed (400) facets. The oxygen vacancies and acid sites on the catalyst surface can precisely adsorb -CHO and -CH₂-OH of HMF, respectively, and this synergistic effect promotes the efficient production of FDCA. This work is of great significance for fundamentally study the effect of micro-topography or crystal-plane reaction properties on surfaces.

Conjugated polyaniline as “conveyor” in tungstate boosting cation storage for high-performance aqueous batteries

Yanyan Liu, Zirui Shao, Tianming Lv, Zilong Zhang, Zhenhua Zhou, Tao Hu, Changgong Meng, Yifu Zhang

2025, 10(4): 766-779. doi: 10.1016/j.gee.2024.06.004

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Aqueous ion storage systems have motivated great interest by virtue of low reduction, high eco-sustainability and safety. Among various cathode candidates, transition metal compounds are featured with easy dissolution in aqueous solutions and inferior conductivity, which severely hinder their application. Herein, advantages are taken of the “conveyor effect” of conjugated polyaniline to prepare an oxygen defective tungstate-linked polyaniline (O_d-WOP) material with chrysanthemum-like microstructure. By virtue of the high electronic conductivity derived from conductive conjugated polyaniline skeleton, unbalanced charge distribution triggered by the defective structure, and reversibly rapid ion (de) intercalation benefited from the open framework with porous chrysanthemum-like microstructure, it delivers outstanding rate capability with a maximum specific capacity of 162.2 mAh g^-1 and great cycle stability for storing NH₄⁺. Additionally, it also adopts a high reversible capacity of 140.4 mAh g^-1 and outstanding cycling performance to store Ca²⁺. Consequently, the assembled O_d-WOP//PTCDI flexible aqueous ammonium ion batteries and calcium ion batteries exhibit superior capacities, energy densities and flexibilities. O_d-WOP achieves the NH₄⁺ and Ca²⁺ storage capability by interacting with them through hydrogen and ionic bonds, respectively. The deep insight from this work sheds light upon a novel strategy to excavate greater potential of transition metal compounds for aqueous ion batteries.

NiCoMn-LDH with core-shell heterostructures based on CoS nanotube arrays containing multiple ion diffusion channels for boosted supercapacitor applications

Xiaojie Xu, Huachen Lin, Jinrui Ding, Pengjie Zhou, Yulong Ying, Hong Jia, Longhua Li, Yu Liu

2025, 10(4): 780-792. doi: 10.1016/j.gee.2024.06.002

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Nanostructure engineering and composition rationalization are crucial for materials to become candidates for high-performance supercapacitor. Herein, a novel core-shell heterostructured electrode, combining CoS hollow nanorods with NiCoMn-layered double hydroxides (LDH) ternary metal nanosheets, were prepared on carbon cloth by reasonably controlled vulcanization and electrodeposition. By optimizing electrodeposition conditions, the material's structure and properties can be fine-tuned. The enhanced capacitance of the optimized carbon cloth (CC)@CoS/NiCoMn-LDH-300 electrode (4256.0 F g^-1) lies in the open space provided by CoS and the establishment of a new charge transfer channel across the interfaces of CC@CoS/NiCoMn-LDH-300 nanosheets. This is further demonstrated by Density functional theory (DFT) simulations based on OH^- adsorption energy, which produces faster redox charge kinetics and significantly enhances the electrode's energy storage capacity. The hybrid supercapacitor, integrating the optimized CC@CoS/NiCoMn-LDH-300 electrode with active carbon, demonstrates the highest energy density of 86 Wh kg^-1 (under the power density of 850 W kg^-1) and the long cycle stability of 89.7%. This study aims to go beyond simple binary LDH by constructing a ternary LDH with a hierarchical core-shell heterostructure to provide an effective and feasible new concept for high-performance supercapacitor electrode materials via rational structure design.

Synergistic Li₆PS₅Cl@Li₃OCl composite electrolyte for high-performance all-solid-state lithium batteries

Yuzhe Zhang, Haolong Chang, Aiguo Han, Shijie Xu, Xinyu Wang, Shunjin Yang, Xiaohu Hu, Yujiang Sun, Xiao Sun, Xing Chen, Yongan Yang

2025, 10(4): 793-803. doi: 10.1016/j.gee.2024.07.001

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Li₆PS₅Cl is a highly wanted sulfide-solid-electrolyte (SSE) for developing all-solid-state lithium batteries, due to its high ionic conductivity, good processability and abundant compositional elements. However, its cyclability is poor because of harmful side reactions at the Li₆PS₅Cl/Li interface and growth of lithium dendrites inside Li₆PS₅Cl phase. Herein, we report a simple interface-engineering remedy to boost the electrochemical performance of Li₆PS₅Cl, by coating its surface with a Li-compatible electrolyte Li₃OCl having low electronic conductivity. The obtained Li₆PS₅Cl@Li₃OCl core@shell structure exhibits a synergistic effect. Consequently, compared with the bare Li₆PS₅Cl, this composite electrolyte exhibits great performance improvements: 1) In LielectrolyteLi symmetric cells, the critical current density at 30 ℃ gets increased from 0.6 mA cm^-2 to 1.6 mA cm^-2, and the lifetime gets prolonged from 320 h to 1400 h at the cycling current of 0.2 mA cm^-2 or from 10 h to 900 h at the cycling current of 0.5 mA cm^-2; 2) In Li|electrolyte|NCM721 full cells running at 30 ℃, the cycling capacity at 0.2 C (or 0.5 C) gets enhanced by 20% (or from unfeasible to be feasible) for 100 cycles and the rate capability reaches up to 2 C from 0.2 C; and in full cells running at 60 ℃, the cycling capacity is increased by 7% at 0.2 C and the rate capability is enhanced to 3.0 C from 0.5 C. The experimental studies and theoretical computations show that the performance enhancements are due to the confined electron penetration and suppressed lithium dendrites growth at the Li₆PS₅Cl@Li₃OCl interface.

Rational engineering of triazine-benzene linked covalent-organic frameworks for efficient CO₂ photoreduction

Yanghe Fu, Yijing Gao, Huilin Jia, Yuncai Zhao, Yan Feng, Weidong Zhu, Fumin Zhang, Morris D. Argyle, Maohong Fan

2025, 10(4): 804-812. doi: 10.1016/j.gee.2024.07.002

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Three large π-conjugated and imine-based COFs, named TFP-TAB, TFP-TTA, and TTA-TTB, were synthesized via the ordered incorporation of benzene and triazine rings in the same host framework to study how the structural units affect the efficiency of CO₂ photoreduction. Results from both experiments and density-functional theory (DFT) calculations indicate the separation and transfer of the photoinduced charges is highly related to the triazine-N content and the conjugation degree in the skeletons of COFs. High-efficiency CO₂ photoreduction can be achieved by rationally adjusting the number and position of both benzene and triazine rings in the COFs. Specifically, TTA-TTB, with orderly interlaced triazine-benzene heterojunctions, can suppress the recombination probability of electrons and holes, which effectively immobilizes the key species (COOH) and lowers the free energy change of the potential-determining step, and thus exhibits a superior visible-light-induced photocatalytic activity that yields 121.7 μmol HCOOH g^-1 h^-1. This research, therefore, helps to elucidate the effects of the different structural blocks in COFs on inherent heterogeneous photocatalysis for CO₂ reduction at a molecular level.

Boosting electrochemical reduction of CO₂ to CO using molecule-regulated Ag nanoparticle in ionic liquids

Fangfang Li, Kuilin Peng, Chongyang Jiang, Shaojuan Zeng, Xiangping Zhang, Xiaoyan Ji

2025, 10(4): 813-820. doi: 10.1016/j.gee.2024.07.005

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Electrochemical reduction of CO₂ is a promising approach to convert CO₂ to high-valued chemicals and fuels. However, developing efficient electrocatalysts featuring desirable activity and selectivity is still a big challenge. In this work, a strategy of introducing functionalized molecules with desirable CO₂ affinity to regulate Ag catalyst for promoting electrochemical reduction of CO₂ was proposed. Specifically, 3-mercapto-1,2,4-triazole was introduced onto the Ag nanoparticle (Ag-m-Triz) for the first time to achieve selectively converting CO₂ to carbon monoxide (CO). This Ag-m-Triz exhibits excellent performance for CO₂ reduction with a high CO Faradaic efficiency (FE_CO) of 99.2% and CO partial current density of 85.0 mA cm^-2 at -2.3 V vs. Ag/Ag⁺ in H-cell when combined with the ionic liquid-based electrolyte, 30 wt% 1-butyl-3-methylimidazolium hexafluorophosphate ([Bmim][PF₆])-65 wt% acetonitrile (AcN)-5 wt% H₂O, which is 2.5-fold higher than the current density in Ag-powder under the same condition. Mechanism studies confirm that the significantly improved performance of Ag-m-Triz originates from (i) the stronger adsorption ability of CO₂ molecule and (ii) the weaker binding energy to form the COOH^* intermediate on the surface of Ag-m-Triz compared with the Ag-powder catalyst, which boosts the conversion of CO₂ to CO. This research provides a facile way to regulate electrocatalysts for efficient CO₂ reduction by introducing functionalized molecules.

Enhanced interlayer interaction in sulfonated CONs membrane by amino-rich CONs enabling ultrafast proton transport

Ping Li, Bo He, Xuan Li, Yunfei Lin, Shaokun Tang

2025, 10(4): 821-833. doi: 10.1016/j.gee.2024.07.008

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Covalent organic framework nanosheets (CONs) with porous crystalline features and ultrathin thickness are ideal candidates as membrane building blocks to form well-defined transfer nanochannels. The formidable challenge behind self-supporting CONs membrane lies in weak non-covalent interlayer interactions and thus loose stacking, insufficient strength and structure stabilities. Herein, we propose the fabrication of interlayer force-strengthened freestanding CONs membrane through the electrostatic attraction bridge effect of positively-charged amino-rich CONs (CON-NH₂) to negatively-charged sulfonated CONs (CON-SO₃H). Ultrathin and large lateral sized CON-SO₃H and CON-NH₂ are synthesized, followed by restacking to prepare freestanding CONs membrane with CON-SO₃H as the membrane bulk. Benefiting from effective interlayer interconnection due to strong electrostatic interaction, the obtained CON-SO₃H/CON-NH₂ membrane displays features of ultrahigh integrity, dense stacking, eminent water/acid/base/organic solvents stabilities and mechanical strength (109 MPa). The shortened -SO₃H distance contributes to construct site-continuous transfer pathways, and the deprotonated -SO₃H and protonated -NH₂ form acid-base pairs to decrease interfacial resistance, which impart membrane superior proton conductivity of 486 mS cm^-1 (80 ℃, 100% RH). This interlayer force enhancement strategy offers a promising perspective on achieving densely-stacked CONs membrane with ultrahigh mechanical property and conduction performance for fuel cell application.

Superhydrophobic ceramic membrane coupled with a biphasic solvent for efficient CO₂ capture

Kaili Xue, Zhen Chen, Xiaona Wu, Heng Zhang, Haiping Chen, Junhua Li

2025, 10(4): 834-844. doi: 10.1016/j.gee.2024.07.010

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An innovative strategy was proposed by integration of membrane contactor (MC) with biphasic solvent for efficient CO₂ capture from flue gas. The accessible fly ash-based ceramic membrane (CM) underwent hydrophobic modification through silane grafting, followed by fluoroalkylsilane decoration, to prepare the superhydrophobic membrane (CSCM). The CSCM significantly improved resistance to wetting by the biphasic solvent, consisting of amine (DETA) and sulfolane (TMS). Morphological characterizations and chemical analysis revealed the notable enhancements in pore structure and hydrophobic chemical groups for the modified membrane. Predictions of wetting/bubbling behavior based on static wetting theory referred the liquid entry pressure (LEP) of CSCM increased by 20 kPa compared to pristine CM. Compared with traditional amine solvents, the biphasic solvent presented the expected phase separation. Performance experiments demonstrated that the CO₂ capture efficiency of the biphasic solvent increased by 7%, and the electrical energy required for desorption decreased by 32%. The 60-h continuous testing and supplemental characterization of used membrane confirmed the excellent adaptability and durability of the CSCMs. This study provides a potential approach for accessing hydrophobic ceramic membranes and biphasic solvents for industrial CO₂ capture.

2,6-Diaminoanthraquinone modified MXene (Ti₃C₂T_x)/graphene as the negative electrode materials for ionic liquid-based asymmetric supercapacitors

Li Sun, Lujia Chai, Liangqi Jing, Yujuan Chen, Kelei Zhuo, Jianji Wang

2025, 10(4): 845-853. doi: 10.1016/j.gee.2024.08.004

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Due to insufficient energy density, supercapacitors (SCs) with preeminent-power and long cycle stability cannot be implemented in some practical applications. Exploring hybrid materials with redox activity to emerge high specific capacitance in ionic liquid (IL) electrolytes can solve this problem. Herein, we report a redox-organic molecule 2,6-diaminoanthraquinone (DAAQ) modified MXene (Ti₃C₂T)/Graphene (DAAQ-M/G) composite material. With the assist of graphene oxide (GO), MXene and graphene fabricate a three-dimensional (3D) interconnected structure as a conductive framework, which inhibits self-stacking of MXene monolayers and ensures high electronic conductivity. Meanwhile, DAAQ is loaded onto the M/G framework through covalent/non-covalent functionalization. The DAAQ as a spacer effectively enlarges the interlayer spacing of MXene nanosheets, and meanwhile produces reversible redox reactions during charge/discharge processes to provide additional Faradaic contribution to capacity. Therefore, the specific capacitance (capacity) of the DAAQ-M/G as the negative electrode material reaches to 226 F g^-1 (306 C g^-1) at 1 A g^-1 in 1-ethyl-3-methylimidazolium tetrafluoroborate (EmimBF₄) electrolyte. Furthermore, an asymmetric supercapacitor (ASC) is assembled using DAAQ-M/G as the negative electrode and self-prepared organic molecule hydroquinone modified reduced graphene oxide (HQ-RGO) material as the positive electrode, with a high energy density of 43 Wh kg^-1 at high power density of 1669 W kg^-1. The ASC can maintain 80% of initial specific capacitance after 9000 cycles. This research can provide better support to develop advanced organic molecules-modified MXene composite materials for ionic liquid-based SCs.

Ti₃C₂ MXene nanosheets integrated cobalt-doped nickel hydroxide heterostructured composite: An efficient electrocatalyst for overall water-splitting

Amaranadha Reddy Manchuri, Kamakshaiah Charyulu Devarayapalli, Bolam Kim, Youngsu Lim, Dae Sung Lee

2025, 10(4): 854-868. doi: 10.1016/j.gee.2024.08.006

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Developing an efficient electrocatalyst for superior electrochemical water splitting (EWS) is crucial for achieving comprehensive hydrogen production. A heterostructured electrocatalyst, free of noble metals, Ti₃C₂ MXene nanosheet-integrated cobalt-doped nickel hydroxide (NHCoMX) composite was synthesized via a hydrothermal method. The abundant pores in the Ti₃C₂ MXene nanosheet (MX)-integrated microarchitecture increased the number of active sites and facilitated charge transfer, thus enhancing electrocatalysis. Specifically, the MX-enhanced charge transfer considerably transformed the microelectronic structure of cobalt-doped Ni(OH)₂(NHCo), which promoted its hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Hence, as an EWS catalyst, NHCoMX exhibited an exceptional electrocatalytic activity, demonstrating OER and HER overpotentials of 310 mV and 73 mV, respectively, with low Tafel slopes of 65 mV dec^-1 and 85 mV dec^-1, respectively; it exhibited a current density of 10 mV cm^-2 in 1.0 mol L^-1 KOH, representing the closest efficiency to the noble state-of-the-art RuO₂ and Pt/C catalyst. Furthermore, the developed electrocatalyst improved the activities of both HER and OER, leading to an overall EWS current density of 10 mA cm^-2 at 1.72 V in an alkaline electrolyte with two electrodes. This study describes an efficient heterostructured NHCoMX composite electrocatalyst. It is significantly comparable to the noble state-of-the-art electrocatalysts and can be extended to fabricate resourceful catalysts for large-scale EWS applications.

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