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Chinese Journal of Catalysis
2024, Vol. 63
Online: 18 August 2024

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Cover: Qiao-Ling Mo and co-workers have developed a novel photocatalytic system that utilizes ZnIn2S4 encapsulated in a non-conjugated insulating polymer (bPEI). This bPEI/ZIS hybrid material significantly enhances photocatalytic performance, demonstrating efficient selective organic transformation and hydrogen evolution under visible light irradiation. This innovative strategy sheds the light on the smart utilization of non-conjugated insulating polymers as co-catalyst to boost interfacial charge separation and migration efficiency in heterogeneous photocatalysis. Read more about the article behind the cover on page 109–123.

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Advances in the studies of the supported ruthenium catalysts for CO2 methanation Chenyang Shen, Menghui Liu, Song He, Haibo Zhao, Chang-jun Liu 2024, 63:  1-15.  DOI: 10.1016/S1872-2067(24)60090-2 Abstract ( 243 )   HTML ( 22 )   PDF (2827KB) ( 104 )   CO2 methanation has a potential in the large-scale utilization of carbon dioxide. It has also been considered to be useful for the renewable energy storage. The commercial pipeline for natural gas transportation can be directly applied for the methane product of CO2 methanation. The supported ruthenium (Ru) catalyst has been confirmed to be active and stable for CO2 methanation with its high ability in the dissociation of hydrogen and the strong binding of carbon monoxide. CO2 methanation over the supported Ru catalyst is structure sensitive. The size of the Ru catalyst and the support have significant effects on the activity and the mechanism. A significant challenge remained is the structural controllable preparation of the supported Ru catalyst toward a sufficiently high low-temperature activity. In this review, the recent progresses in the investigations of the supported Ru catalysts for CO2 methanation are summarized. The challenges and the future developments are also discussed.

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Cation effects in electrocatalytic reduction reactions: Recent advances Qinghui Ren, Liang Xu, Mengyu Lv, Zhiyuan Zhang, Zhenhua Li, Mingfei Shao, Xue Duan 2024, 63:  16-32.  DOI: 10.1016/S1872-2067(24)60080-X Abstract ( 261 )   HTML ( 21 )   PDF (12205KB) ( 145 )   Electrocatalytic reduction reactions, powered by clean energy sources such as solar energy and wind, offer a sustainable method for converting inexpensive feedstocks (e.g., CO2, N2/NOx, organics, and O2) into high-value-added chemicals or fuels. The design and modification of electrocatalysts have been widely implemented to improve their performance in these reactions. However, bottlenecks are encountered, making it challenging to further improve performance through catalyst development alone. Recently, cations in the electrolyte have emerged as critical factors for tuning both the activity and product selectivity of reduction reactions. This review summarizes recent advances in understanding the role of cation effects in electrocatalytic reduction reactions. First, we introduce the mechanisms underlying cation effects. We then provide a comprehensive overview of their application in electroreduction reactions. Characterization techniques and theoretical calculation methods for studying cation effects are also discussed. Finally, we address remaining challenges and future perspectives in this field. We hope that this review offers fundamental insights and design guidance for utilizing cation effects, thereby advancing their development.

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Recent advances in design of hydrogen evolution reaction electrocatalysts at high current density: A review Zhipeng Li, Xiaobin Liu, Qingping Yu, Xinyue Qu, Jun Wan, Zhenyu Xiao, Jingqi Chi, Lei Wang 2024, 63:  33-60.  DOI: 10.1016/S1872-2067(24)60076-8 Abstract ( 142 )   HTML ( 2 )   PDF (10452KB) ( 65 )   The electrolysis of water powered by renewable energy sources offers a promising method of "green hydrogen" production, which is considered to be at the heart of future carbon-neutral energy systems. In the past decades, researchers have reported a number of hydrogen evolution reaction (HER) electrocatalysts with activity comparable to that of commercial Pt/C, but most of them are tested within a small current density range, typically no more than 500 mA cm-2. To realize the industrial application of hydrogen production from water electrolysis, it is essential to develop high-efficiency HER electrocatalysts at high current density (HCD ≥ 500 mA cm-2). Nevertheless, it remains challenging and significant to rational design HCD electrocatalysts for HER. In this paper, the design strategy of HCD electrocatalysts is discussed, and some HCD electrocatalysts for HER are reviewed in seven categories (alloy, metal oxide, metal hydroxide, metal sulfide/selenide, metal nitride, metal phosphide and other derived electrocatalysts). At the end of this article, we also propose some viewpoints and prospects for the future development and research directions of HCD electrocatalysts for HER.

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Enhancing selectivity in acidic CO2 electrolysis: Cation effects and catalyst innovation Zichao Huang, Tinghui Yang, Yingbing Zhang, Chaoqun Guan, Wenke Gui, Min Kuang, Jianping Yang 2024, 63:  61-80.  DOI: 10.1016/S1872-2067(24)60073-2 Abstract ( 154 )   HTML ( 8 )   PDF (14410KB) ( 46 )   The electrochemical reduction of CO2 (eCO2R) under ambient conditions is crucial for reducing carbon emissions and achieving carbon neutrality. Despite progress with alkaline and neutral electrolytes, their efficiency is limited by (bi)carbonates formation. Acidic media have emerged as a solution, addressing the (bi)carbonates challenge but introducing the issue of the hydrogen evolution reaction (HER), which reduces CO2 conversion efficiency in acidic environments. This review focuses on enhancing the selectivity of acidic CO2 electrolysis. It commences with an overview of the latest advancements in acidic CO2 electrolysis, focusing on product selectivity and electrocatalytic activity enhancements. It then delves into the critical factors shaping selectivity in acidic CO2 electrolysis, with a special emphasis on the influence of cations and catalyst design. Finally, the research challenges and personal perspectives of acidic CO2 electrolysis are suggested.

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Chalcogenide-based S-scheme heterojunction photocatalysts Chunguang Chen, Jinfeng Zhang, Hailiang Chu, Lixian Sun, Graham Dawson, Kai Dai 2024, 63:  81-108.  DOI: 10.1016/S1872-2067(24)60072-0 Abstract ( 113 )   HTML ( 6 )   PDF (14275KB) ( 39 )   The unique photocatalytic mechanism of S-scheme heterojunction can be used to study new and efficient photocatalysts. By carefully selecting semiconductors for S-scheme heterojunction photocatalysts, it is possible to reduce the rate of photogenerated carrier recombination and increase the conversion efficiency of light into energy. Chalcogenides are a group of compounds that include sulfides and selenides (e.g., CdS, ZnS, Bi2S3, MoS2, ZnSe, CdSe, and CuSe). Chalcogenides have attracted considerable attention as heterojunction photocatalysts owing to their narrow bandgap, wide light absorption range, and excellent photoreduction properties. This paper presents a thorough analysis of S-scheme heterojunction photocatalysts based on chalcogenides. Following an introduction to the fundamental characteristics and benefits of S-scheme heterojunction photocatalysts, various chalcogenide-based S-scheme heterojunction photocatalyst synthesis techniques are summarized. These photocatalysts are used in numerous significant photocatalytic reactions, including the reduction of carbon dioxide, synthesis of hydrogen peroxide, conversion of organic matter, generation of hydrogen from water, nitrogen fixation, degradation of organic pollutants, and sterilization. In addition, cutting-edge characterization techniques, including in situ characterization techniques, are discussed to validate the steady and transient states of photocatalysts with an S-scheme heterojunction. Finally, the design and challenges of chalcogenide-based S-scheme heterojunction photocatalysts are explored and recommended in light of state-of-the-art research.

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Identification of origin of insulating polymer maneuvered photoredox catalysis Qiao-Ling Mo, Rui Xiong, Jun-Hao Dong, Bai-Sheng Sa, Jing-Ying Zheng, Qing Chen, Yue Wu, Fang-Xing Xiao 2024, 63:  109-123.  DOI: 10.1016/S1872-2067(24)60070-7 Abstract ( 126 )   HTML ( 8 )   PDF (5834KB) ( 47 )   Supporting Information Solid non-conjugated polymers have long been regarded as insulators due to deficiency of delocalized π electrons along the molecular chain framework. Up to date, origin of insulating polymer regulated charge transfer has not yet been uncovered. In this work, we unleash the root origin of charge transport capability of insulating polymer in photocatalysis. We ascertain that insulating polymer plays crucial roles in fine tuning of electronic structure of transition metal chalcogenides (TMCs), which mainly include altering surface electron density of TMCs for accelerating charge transport kinetics, triggering the generation of defect over TMCs for prolonging carrier lifetime, and acting as hole-trapping mediator for retarding charge recombination. These synergistic roles contribute to the charge transfer of insulating polymer. Our work opens a new vista of utilizing solid insulating polymers for maneuvering charge transfer toward solar energy conversion.

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Is platinum-loaded titania the best material for dye-sensitized hydrogen evolution under visible light? Haruka Yamamoto, Langqiu Xiao, Yugo Miseki, Hiroto Ueki, Megumi Okazaki, Kazuhiro Sayama, Thomas E. Mallouk, Kazuhiko Maeda 2024, 63:  124-132.  DOI: 10.1016/S1872-2067(24)60092-6 Abstract ( 202 )   HTML ( 0 )   PDF (1823KB) ( 42 )   Supporting Information A dye-sensitized photocatalyst combining Pt-loaded TiO2 and Ru(II) tris-diimine sensitizer (RuP) was constructed and its activity for photochemical hydrogen evolution was compared with that of Pt-intercalated HCa2Nb3O10 nanosheets. When the sacrificial donor ethylenediaminetetraacetic acid (EDTA) disodium salt dihydrate was used, RuP/Pt/TiO2 showed higher activity than RuP/Pt/HCa2Nb3O10. In contrast, when NaI (a reversible electron donor) was used, RuP/Pt/TiO2 showed little activity due to back electron transfer to the electron acceptor (I3-), which was generated as the oxidation product of I-. By modification with anionic polymers (sodium poly(styrenesulfonate) or sodium polymethacrylate) that could inhibit the scavenging of conduction band electrons by I3-, the H2 production activity from aqueous NaI was improved, but it did not exceed that of RuP/Pt/HCa2Nb3O10. Transient absorption measurements showed that the rate of semiconductor-to-dye back electron transfer was slower in the case of TiO2 than HCa2Nb3O10, but the electron transfer reaction to I3- was much faster. These results indicate that Pt/TiO2 is useful for reactions with sacrificial reductants (e.g., EDTA), where the back electron transfer reaction to the more reducible product can be neglected. However, more careful design of the catalyst will be necessary when a reversible electron donor is employed.

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Tailoring the microenvironment of Ti sites in Ti-containing materials for synergizing with Au sites to boost propylene epoxidation Shudong Shi, Zhihua Zhang, Yundao Jing, Wei Du, Xuezhi Duan, Xinggui Zhou 2024, 63:  133-143.  DOI: 10.1016/S1872-2067(24)60083-5 Abstract ( 113 )   HTML ( 3 )   PDF (3933KB) ( 28 )   Supporting Information Au sites supported on Ti-containing materials (Au/Ti-containing catalyst) are currently considered as a promising catalyst for the propylene epoxidation owing to the synergistic effect that hydrogen peroxide species formed on Au sites diffuses to the Ti sites to form the Ti-hydroperoxo intermediates and contributes to the formation of propylene oxide (PO). In principle, thermal treatment will significantly affect the chemical and physical structures of Ti-containing materials. Consequently, the synergy between tailored Ti sites with different surface properties and Au sites is highly expected to enhance the catalytic performance for the reaction. Herein, we systematically studied the intrinsic effects of different microenvironments around Ti sites on the PO adsorption/desorption and conversion, and then effectively improved the catalytic performance by tailoring the number of surface hydroxyl groups. The TiVI material with fewer hydroxyls stimulates a remarkable enhancement in PO selectivity and H2 efficiency compared to the TiVI material that possessed more hydroxyls, offering a 7-fold and 4-fold increase, respectively. As expected, the TiVI+IV and TiIV materials also exhibit a similar phenomenon to the TiVI materials through the same thermal treatment, which strongly supports that the Ti sites microenvironment is an important factor in suppressing PO conversion and enhancing catalytic performance. These insights could provide guidance for the rational preparation and optimization of Ti-containing materials synergizing with Au catalysts for propylene epoxidation.

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A dendritic Cu/Cu2O structure with high curvature enables rapid and efficient reduction of carbon dioxide to C2 in an H-cell Lei Shao, Bochen Hu, Jinhui Hao, Junjie Jin, Weidong Shi, Min Chen 2024, 63:  144-153.  DOI: 10.1016/S1872-2067(24)60079-3 Abstract ( 122 )   HTML ( 3 )   PDF (5986KB) ( 52 )   Supporting Information Electrocatalytic reduction of CO2 (CO2RR) to multicarbon products is an efficient approach for addressing the energy crisis and achieving carbon neutrality. In H-cells, achieving high-current C2 products is challenging because of the inefficient mass transfer of the catalyst and the presence of the hydrogen evolution reaction (HER). In this study, dendritic Cu/Cu2O with abundant Cu0/Cu+ interfaces and numerous dendritic curves was synthesized in a CO2 atmosphere, resulting in the high selectivity and current density of the C2 products. Dendritic Cu/Cu2O achieved a C2 Faradaic efficiency of 69.8% and a C2 partial current density of 129.5 mA cm‒2 in an H-cell. Finite element simulations showed that a dendritic structure with a high curvature generates a strong electric field, leading to a localized CO2 concentration. Additionally, DRT analysis showed that a dendritic structure with a high curvature actively adsorbed the surrounding high concentration of CO2, enhancing the mass transfer rate and achieving a high current density. During the experiment, the impact of the electronic structure on the performance of the catalyst was investigated by varying the atomic ratio of Cu0/Cu+ on the catalyst surface, which resulted in improved ethylene selectivity. Under the optimal atomic ratio of Cu0/Cu+, the charge transfer resistance was minimized, and the desorption rate of the intermediates was low, favoring C2 generation. Density functional theory calculations indicated that the Cu0/Cu+ interfaces exhibited a lower Gibbs free energy for the rate-determining step, enhancing C2H4 formation. The Cu/Cu2O catalyst also exhibited a low Cu d-band center, which enhanced the adsorption stability of *CO on the surface and facilitated C2 formation. This observation explained the higher yield of C2 products at the Cu0/Cu+ interface than that of H2 under rapid mass transfer. The results of the net present value model showed that the H-cell holds promising industrial prospects, contingent upon it being a catalyst with both high selectivity and high current density. This approach of integrating the structure and composition provides new insights for advancing the CO2RR towards high-current C2 products.

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Amorphous core-shell NiMoP@CuNWs rod-like structure with hydrophilicity feature for efficient hydrogen production in neutral media Jiayong Xiao, Chao Jiang, Hui Zhang, Zhuo Xing, Ming Qiu, Ying Yu 2024, 63:  154-163.  DOI: 10.1016/S1872-2067(24)60086-0 Abstract ( 158 )   HTML ( 11 )   PDF (2168KB) ( 86 )   Supporting Information Using interface engineering, a highly efficient catalyst with a shell@core structure was successfully synthesized by growing an amorphous material composed of Ni, Mo, and P on Cu nanowires (NiMoP@CuNWs). This catalyst only requires an overpotential of 35 mV to reach a current density of 10 mA cm-2. The exceptional hydrogen evolution reaction (HER) activity is attributed to the unique amorphous rod-like nature of NiMoP@CuNWs, which possesses a special hydrophilic feature, enhances mass transfer, promotes effective contact between the electrode and electrolyte solution, and exposes more active sites during the catalytic process. Density functional theory revealed that the introduction of Mo weakens the binding strength of the Ni site on the catalyst surface with the H atom and promotes the desorption process of the H2 product significantly. Owing to its facile synthesis, low cost, and high catalytic performance, this electrocatalyst is a promising option for commercial applications as a water electrolysis catalyst.

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Superposition of dual electric fields in covalent organic frameworks for efficient photocatalytic hydrogen evolution Chao Li, Shuo Wang, Yuan Liu, Xihe Huang, Yan Zhuang, Shuhong Wu, Ying Wang, Na Wen, Kaifeng Wu, Zhengxin Ding, Jinlin Long 2024, 63:  164-175.  DOI: 10.1016/S1872-2067(24)60075-6 Abstract ( 101 )   HTML ( 5 )   PDF (6563KB) ( 32 )   Supporting Information Covalent organic frameworks (COFs) are promising materials for converting solar energy into green hydrogen. However, limited charge separation and transport in COFs impede their application in the photocatalytic hydrogen evolution reaction (HER). In this study, the intrinsically tunable internal bond electric field (IBEF) at the imine bonds of COFs was manipulated to cooperate with the internal molecular electric field (IMEF) induced by the donor-acceptor (D-A) structure for an efficient HER. The aligned orientation of IBEF and IMEF resulted in a remarkable H2 evolution rate of 57.3 mmol·g-1·h-1 on TNCA, which was approximately 520 times higher than that of TCNA (0.11 mmol·g-1·h-1) with the opposing electric field orientation. The superposition of the dual electric fields enables the IBEF to function as an accelerating field for electron transfer, kinetically facilitating the migration of photogenerated electrons from D to A. Furthermore, theoretical calculations indicate that the inhomogeneous charge distribution at the C and N atoms in TNCA not only provides a strong driving force for carrier transfer but also effectively hinders the return of free electrons to the valence band, improving the utilization of photoelectrons. This strategy of fabricating dual electric fields in COFs offers a novel approach to designing photocatalysts for clean energy synthesis.

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Self-assembled S-scheme In2.77S4/K+-doped g-C3N4 photocatalyst with selective O2 reduction pathway for efficient H2O2 production using water and air Qiqi Zhang, Hui Miao, Jun Wang, Tao Sun, Enzhou Liu 2024, 63:  176-189.  DOI: 10.1016/S1872-2067(24)60077-X Abstract ( 108 )   HTML ( 4 )   PDF (7424KB) ( 38 )   Supporting Information The development of an efficient artificial H2O2 photosynthesis system is a challenging work using H2O and O2 as starting materials. Herein, 3D In2.77S4 nanoflower precursor was in-situ deposited on K+-doped g-C3N4 (KCN) nanosheets using a solvothermal method, then In2.77S4/KCN (IS/KCN) heterojunction with an intimate interface was obtained after a calcination process. The investigation shows that the photocatalytic H2O2 production rate of 50IS/KCN can reach up to 1.36 mmol g-1 h-1 without any sacrificial reagents under visible light irradiation, which is 9.2 times and 4.1 times higher than that of KCN and In2.77S4, respectively. The enhanced activity of the above composite can be mainly attributed to the S-scheme charge transfer route between KCN and In2.77S4 according to density functional theory calculations, electron paramagnetic resonance and free radical capture tests, leading to an expanded light response range and rapid charge separation at their interface, as well as preserving the active electrons and holes for H2O2 production. Besides, the unique 3D nanostructure and surface hydrophobicity of IS/KCN facilitate the diffusion and transportation of O2 around the active centers, the energy barriers of O2 protonation and H2O2 desorption steps are effectively reduced over the composite. In addition, this system also exhibits excellent light harvesting ability and stability. This work provides a potential strategy to explore a sustainable H2O2 photosynthesis pathway through the design of heterojunctions with intimate interfaces and desired reaction thermodynamics and kinetics.

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Molten salt construction of core-shell structured S-scheme CuInS2@CoS2 heterojunction to boost charge transfer for efficient photocatalytic CO2 reduction Fulin Wang, Xiangwei Li, Kangqiang Lu, Man Zhou, Changlin Yu, Kai Yang 2024, 63:  190-201.  DOI: 10.1016/S1872-2067(24)60066-5 Abstract ( 150 )   HTML ( 1 )   PDF (19598KB) ( 68 )   Supporting Information Weak redox ability and severe charge recombination pose significant obstacles to the advancement of CO2 photoreduction. To tackle this challenge and enhance the CO2 photoconversion efficiency, fabricating well-matched S-scheme heterostructure and establishing a robust built-in electric field emerge as pivotal strategies. In pursuit of this goal, a core-shell structured CuInS2@CoS2 S-scheme heterojunction was meticulously engineered through a two-step molten salt method. This approach over the CuInS2-based composites produced an internal electric field owing to the disparity between the Fermi levels of CoS2 and CuInS2 at their interface. Consequently, the electric field facilitated the directed migration of charges and the proficient separation of photoinduced carriers. The resulting CuInS2@CoS2 heterostructure exhibited remarkable CO2 photoreduction performance, which was 21.7 and 26.5 times that of pure CuInS2 and CoS2, respectively. The S-scheme heterojunction photogenerated charge transfer mechanism was validated through a series of rigorous analyses, including in situ irradiation X-ray photoelectron spectroscopy, work function calculations, and differential charge density examinations. Furthermore, in situ infrared spectroscopy and density functional theory calculations corroborated the fact that the CuInS2@CoS2 heterojunction substantially lowered the formation energy of *COOH and *CO. This study demonstrates the application potential of S-scheme heterojunctions fabricated via the molten salt method in the realm of addressing carbon-related environmental issues.

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Boosting CO2 photoreduction by synergistic optimization of multiple processes through metal vacancy engineering Jinlong Wang, Dongni Liu, Mingyang Li, Xiaoyi Gu, Shiqun Wu, Jinlong Zhang 2024, 63:  202-212.  DOI: 10.1016/S1872-2067(24)60074-4 Abstract ( 134 )   HTML ( 8 )   PDF (3786KB) ( 44 )   Supporting Information The photoreduction of greenhouse gas CO2 using photocatalytic technologies not only benefits environmental remediation but also facilitates the production of raw materials for chemicals. However, the efficiency of CO2 photoreduction remains generally low due to the challenging activation of CO2 and the limited light absorption and separation of charge. Defect engineering of catalysts represents a pivotal strategy to enhance the photocatalytic activity for CO2, with most research on metal oxide catalysts focusing on the creation of anionic vacancies. The exploration of metal vacancies and their effects, however, is still underexplored. In this study, we prepared an In2O3 catalyst with indium vacancies (VIn) through defect engineering for CO2 photoreduction. Experimental and theoretical calculations results demonstrate that VIn not only facilitate light absorption and charge separation in the catalyst but also enhance CO2 adsorption and reduce the energy barrier for the formation of the key intermediate *COOH during CO2 reduction. Through metal vacancy engineering, the activity of the catalyst was 7.4 times, reaching an outstanding rate of 841.32 µmol g‒1 h‒1. This work unveils the mechanism of metal vacancies in CO2 photoreduction and provides theoretical guidance for the development of novel CO2 photoreduction catalysts.

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Conjugated microporous polymers-scaffolded enzyme cascade systems with enhanced catalytic activity Zhenhua Wu, Jiafu Shi, Boyu Zhang, Yushuai Jiao, Xiangxuan Meng, Ziyi Chu, Yu Chen, Yiran Cheng, Zhongyi Jiang 2024, 63:  213-223.  DOI: 10.1016/S1872-2067(24)60088-4 Abstract ( 134 )   HTML ( 6 )   PDF (3519KB) ( 34 )   Supporting Information Enhancing catalytic activity of multi-enzyme in vitro through substrate channeling effect is promising yet challenging. Herein, conjugated microporous polymers (CMPs)-scaffolded integrated enzyme cascade systems (I-ECSs) are constructed through co-entrapping glucose oxidase (GOx) and horseradish peroxidase (HRP), in which hydrogen peroxide (H2O2) is the intermediate product. The interplay of low-resistance mass transfer pathway and appropriate pore wall-H2O2 interactions facilitates the directed transfer of H2O2, resulting in 2.4-fold and 5.0-fold elevation in catalytic activity compared to free ECSs and separated ECSs, respectively. The substrate channeling effect could be regulated by altering the mass ratio of GOx to HRP. Besides, I-ECSs demonstrate excellent stabilities in harsh environments and multiple recycling.

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Catalytically altering the redox pathway of sulfur in propylene carbonate electrolyte using dual-nitrogen/oxygen-containing carbon Linghui Yu, Heng Zhang, Luyuan Paul Wang, Samuel Jun Hoong Ong, Shibo Xi, Bo Chen, Rui Guo, Ting Wang, Yonghua Du, Wei Chen, Ovadia Lev, Zhichuan J. Xu 2024, 63:  224-233.  DOI: 10.1016/S1872-2067(24)60096-3 Abstract ( 86 )   HTML ( 2 )   PDF (3056KB) ( 13 )   Supporting Information Carbonate electrolytes are one of the most desirable electrolytes for high-energy lithium-sulfur batteries (LSBs) because of their successful implementation in commercial Li-ion batteries. The low-polysulfide-solubility feature of some carbonate solvents also makes them very promising for overcoming the shuttle effects of LSBs. However, regular sulfur electrodes experience undesired electrochemical mechanisms in carbonate electrolytes due to side reactions. In this study, we report a catalytic redox mechanism of sulfur in propylene carbonate (PC) electrolyte based on a comparison study. The catalytic mechanism is characterized by the interactions between polysulfides and dual N/O functional groups on the host carbon, which largely prevents side reactions between polysulfides and the carbonate electrolyte. Such a mechanism coupled with the low-polysulfide-solubility feature leads to stable cycling of LSBs in PC electrolyte. Favorable dual N/O functional groups are identified via a density functional theory study. This work provides an alternative route for enabling LSBs in carbonate electrolytes.

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Engineering the coordination structure of Cu for enhanced photocatalytic production of C1 chemicals from glucose Lulu Sun, Shiyang Liu, Taifeng Liu, Dongqiang Lei, Nengchao Luo, Feng Wang 2024, 63:  234-243.  DOI: 10.1016/S1872-2067(24)60098-7 Abstract ( 93 )   HTML ( 2 )   PDF (2477KB) ( 39 )   Supporting Information Photocatalytic decomposition of sugars is a promising way of providing H2, CO, and HCOOH as sustainable energy vectors. However, the production of C1 chemicals requires the cleavage of robust C-C bonds in sugars with concurrent production of H2, which remains challenging. Here, the photocatalytic activity for glucose decomposition to HCOOH, CO (C1 chemicals), and H2 on Cu/TiO2 was enhanced by nitrogen doping. Owing to nitrogen doping, atomically dispersed and stable Cu sites resistant to light irradiation are formed on Cu/TiO2. The electronic interaction between Cu and nitrogen ions originates valence band structure and defect levels composed of N 2p orbit, distinct from undoped Cu/TiO2. Therefore, the lifetime of charge carriers is prolonged, resulting in the production of C1 chemicals and H2 with productivities 1.7 and 2.1 folds that of Cu/TiO2. This work provides a strategy to design coordinatively stable Cu ions for photocatalytic biomass conversion.

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Single-atom catalysts based on polarization switching of ferroelectric In2Se3 for N2 reduction Nan Mu, Tingting Bo, Yugao Hu, Ruixin Xu, Yanyu Liu, Wei Zhou 2024, 63:  244-257.  DOI: 10.1016/S1872-2067(24)60084-7 Abstract ( 73 )   HTML ( 0 )   PDF (5162KB) ( 24 )   Supporting Information The polarization switching plays a crucial role in controlling the final products in the catalytic process. The effect of polarization orientation on nitrogen reduction was investigated by anchoring transition metal atoms to form active centers on ferroelectric material In2Se3. During the polarization switching process, the difference in surface electrostatic potential leads to a redistribution of electronic states. This affects the interaction strength between the adsorbed small molecules and the catalyst substrate, thereby altering the reaction barrier. In addition, the surface states must be considered to prevent the adsorption of other small molecules (such as *O, *OH, and *H). Furthermore, the V@↓-In2Se3 possesses excellent catalytic properties, high electrochemical and thermodynamic stability, which facilitates the catalytic process. Machine learning also helps us further explore the underlying mechanisms. The systematic investigation provides novel insights into the design and application of two-dimensional switchable ferroelectric catalysts for various chemical processes.

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Investigating the charge transfer mechanism of ZnSe QD/COF S-scheme photocatalyst for H2O2 production by using femtosecond transient absorption spectroscopy Yanyan Zhao, Chunyan Yang, Shumin Zhang, Guotai Sun, Bicheng Zhu, Linxi Wang, Jianjun Zhang 2024, 63:  258-269.  DOI: 10.1016/S1872-2067(24)60069-0 Abstract ( 174 )   HTML ( 6 )   PDF (9674KB) ( 85 )   Supporting Information Abstract: Hydrogen peroxide (H2O2) has gained widespread attention as a versatile oxidant and a mild disinfectant. Here, an electrostatic self-assembly method is applied to couple ZnSe quantum dots (QDs) with a flower-like covalent organic framework (COF) to form a step-scheme (S-scheme) photocatalyst for H2O2 production. The as-prepared S-scheme photocatalyst exhibits a broad light absorption range with an edge at 810 nm owing to the synergistic effect between the ZnSe QDs and COF. The S-scheme charge-carrier transfer mechanism is validated by performing Fermi level calculations and in-situ X-ray photoelectron and femtosecond transient absorption spectroscopies. Photoluminescence, time-resolved photoluminescence, photocurrent response, electrochemical impedance spectroscopy, and electron paramagnetic resonance results show that the S-scheme heterojunction not only promotes charge carrier separation but also boosts the redox ability, resulting in enhanced photocatalytic performance. Remarkably, a 10%-ZnSe QD/COF has excellent photocatalytic H2O2-production activity, and the optimal S-scheme composite with ethanol as the hole scavenger yields a H2O2-production rate of 1895 mol g-1 h-1. This study presents an example of a high-performance organic/inorganic S-scheme photocatalyst for H2O2 production.

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Continuous-flow electrosynthesis of urea and oxalic acid by CO2-nitrate reduction and glycerol oxidation Shuanglong Zhou, Yue Shi, Yu Dai, Tianrong Zhan, Jianping Lai, Lei Wang 2024, 63:  270-281.  DOI: 10.1016/S1872-2067(24)60085-9 Abstract ( 153 )   HTML ( 7 )   PDF (3763KB) ( 50 )   Supporting Information Urea and oxalic acid are critical component in various chemical manufacturing industries. However, achieving simultaneous generation of urea and oxalic acid in a continuous-flow electrolyzer is a challenge. Herein, we report a continuous-flow electrolyzer equipped with 9-square centimeter-effective area gas diffusion electrodes (GDE) which can simultaneously catalyze the glycerol oxidation reaction in the anode region and the reduction reaction of CO2 and nitrate in the cathode region, producing oxalic acid and urea at both the anode and cathode, respectively. The current density at low cell voltage (0.9 V) remained above 18.7 mA cm-2 for 10 consecutive electrolysis cycles (120 h in total), and the Faraday efficiency of oxalic acid (67.1%) and urea (70.9%) did not decay. Experimental and theoretical studies show that in terms of the formation of C-N bond at the cathode, Pd-sites can provide protons for the hydrogenation process of CO2 and NO3-, Cu-sites can promote the generation of *COOH and Bi-sites can stabilize *COOH. In addition, in terms of glycerol oxidation, the introduction of Cu and Bi into Pd metallene promotes the oxidation of hydroxyl groups and the cleavage of C-C bond in glycerol molecules, respectively.

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Realizing efficient electrochemical oxidation of 5-hydroxymethylfurfural on a freestanding Ni(OH)2/nickel foam catalyst Yunying Huo, Cong Guo, Yongle Zhang, Jingyi Liu, Qiao Zhang, Zhiting Liu, Guangxing Yang, Rengui Li, Feng Peng 2024, 63:  282-291.  Abstract ( 117 )   HTML ( 5 )   PDF (12430KB) ( 34 )   Supporting Information With the continuous improvement of solar energy production capacity, how to effectively use the electricity generated by renewable solar energy for electrochemical conversion of biomass is a hot topic. Electrochemical conversion of 5-hydroxymethylfurfural (HMF) to biofuels and value-added oxygenated commodity chemicals provides a promising and alternative pathway to convert renewable electricity into chemicals. Although nickel-based eletrocatalysts are well-known for HMF oxidation, their relatively low intrinsic activity, poor conductivity and stability still limit the potential applications. Here, we report the fabrication of a freestanding nickel-based electrode, in which Ni(OH)2 species were in-situ constructed on Ni foam (NF) support using a facile acid-corrosion-induced strategy. The Ni(OH)2/NF electrocatalyst exhibits stable and efficient electrochemical HMF oxidation into 2,5-furandicarboxylic acid (FDCA) with HMF conversion close to 100% with high Faraday efficiency. In-situ formation strategy results in a compact interface between Ni(OH)2 and NF, which contributes to good conductivity and stability during electrochemical reactions. The superior performance benefits from dynamic cyclic evolution of Ni(OH)2 to NiOOH, which acts as the reactive species for HMF oxidation to FDCA. A scaled-up device based on a continuous-flow electrolytic cell was also established, giving stable operation with a high FDCA production rate of 27 mg h-1 cm-2. This job offers a straightforward, economical, and scalable design strategy to design efficient and durable catalysts for electrochemical conversion of valuable chemicals.