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Chinese Journal of Catalysis
2024, Vol. 61
Online: 18 June 2024

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Cover: The research team led by Professor Zupeng Chen at Nanjing Forestry University has developed a novel strategy to utilize metal co-catalysts for modulating the reactivity of carbon-centered radical intermediates, which are formed through the cleavage of C–H bonds in biomass-derived alcohols. Experimental and theoretical analysis revealed that different metal co-catalysts exhibit varied adsorption energies towards these intermediates, ultimately leading to a selective production of either C–C coupling products or carbonyl compounds. This research provides new insights into the fundamental mechanisms underlying the selective conversion of biomass-derived alcohols. Read more about the article behind the cover on page 135–143.

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General applications of density functional theory in photocatalysis Shiwen Du, Fuxiang Zhang 2024, 61:  1-36.  DOI: 10.1016/S1872-2067(24)60006-9 Abstract ( 377 )   HTML ( 33 )   PDF (12808KB) ( 236 )   The conversion of solar energy to chemical energies by virtue of semiconductor photocatalysis has shown great significance in sustaining future energy demands, and have a deep understanding of the relationship between photocatalyst and photocatalytic activity is essential. Density functional theory (DFT) calculations are becoming increasingly important for revealing the intrinsic electronic structure properties of materials and energy properties of reactions, which has been greatly developed with the development of computational methods. In this review, the applications of DFT calculations in photocatalysis are summarized and exemplified by various representative investigations in the up-to-date reports. To specify, we show how to collect, analyse and utilize the informations on photocatalysts and photocatalytic reactions with the help of the DFT calculations, such as electronic structures, surface catalytic sites, catalytic activities, possible reaction mechanisms, etc. Our discussion is intended to provide an overview on applications of the current theoretical calculations in the field of photocatalysis for a better understanding of the composition-structure-function relationships, and also to guide future experiments and computations toward the understanding and development of novel solar-energy-conversion catalysts.

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Unveiling the "sono-physico-chemical" essence: Cavitation and vibration effects in ultrasound-assisted processes Wenyuan Liu, Jun Li, Zhuan Chen, Zhiyan Liang, Bo Yang, Kun Du, Jiangchen Fu, Ali Reza Mahjoub, Mingyang Xing 2024, 61:  37-53.  DOI: 10.1016/S1872-2067(24)60028-8 Abstract ( 382 )   HTML ( 26 )   PDF (5975KB) ( 168 )   Ultrasound-assisted processes, widely applied in cleaning, synthesis, and catalysis, exhibit significant application potential, with their impact rooted in the interplay between ultrasound and the physicochemical properties of substances. Therefore, it is emphasized here to understand these processes through a "sono-physico-chemical" angle for a deeper comprehension of reaction mechanisms and broader application. Highlighting cavitation and vibration effects, the ultrasound-assisted chemistry processes are categorized. Cavitation is emphasized for pollutant degradation, while vibration is primarily applied for inducing the piezoelectric effect. Additionally, points that are easy to be ignored in the current ultrasonic assisted catalysis process are proposed, such as synergistic index calculations, cost assessments, etc. Furthermore, the latest innovative application of ultrasonic assisted process in wastewater recycling is introduced. Finally, the review advocates for the future integration of ultrasound-assisted processes into new catalytic processes or application scenarios.

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Rare earth-incorporated high entropy oxides for energy and environmental catalysis Yuou Li, Ke Wang, Xiaomei Wang, Zijian Wang, Jing Xu, Meng Zhao, Xiao Wang, Shuyan Song, Hongjie Zhang 2024, 61:  54-70.  DOI: 10.1016/S1872-2067(24)60012-4 Abstract ( 380 )   HTML ( 27 )   PDF (8281KB) ( 195 )   High entropy oxides have been regarded as one of the most promising catalysts. Their unique and diverse elemental compositions bring stable structures and abundant metal active sites to the catalysts. Notably, rare earth ions have similar radii, unique electron orbitals, and variable valence states. As a result, incorporating rare earth elements into high entropy oxides can effectively adjust the surface state of the catalyst, ultimately improving the structure and properties of the high entropy oxides. However, there is no systematic review on the development of rare earth-incorporated high entropy oxides. In this review, we target the structure, synthesis, and application of rare earth-incorporated high entropy oxides to summarize their research progress in catalysis in recent years. First, we provide an overview of three types of rare earth-incorporated high entropy oxides: fluorite-type, perovskite-type, and pyrochlore-type. Then, the main synthesis methods are discussed in detail, including solid-state reaction, nebulized spray pyrolysis, chemical co-precipitation, and solution combustion. Finally, we analyze the applications of this material in catalytic reactions and suggest possible challenges and solution strategies. It is concluded that this unique material has good prospects for development.

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Recent progress on VOC pollution control via the catalytic method Honghong Zhang, Zhiwei Wang, Lu Wei, Yuxi Liu, Hongxing Dai, Jiguang Deng 2024, 61:  71-96.  DOI: 10.1016/S1872-2067(24)60043-4 Abstract ( 325 )   HTML ( 17 )   PDF (19610KB) ( 176 )   Volatile organic compounds (VOCs) can cause atmospheric environmental problems such as haze and photochemical smog, which seriously restrict the sustainable development of the environment and threaten human health. Effective and comprehensive implementation of VOC prevention is an arduous task. Catalytic oxidation can achieve VOC removal with low energy costs and high efficiency. This review presents representative research progress in thermal or photothermal catalysis over the past ten years, concentrating on various catalysts with distinctive morphologies and structures designed and prepared for investigating single- or multi-component VOC purification, synergetic elimination of VOCs and NOx, and VOCs resource utilization. Furthermore, the influence mechanisms of H2O, CO2, and SO2 on the catalytic stability are summarized. The activity and stability of the catalysts affect their lifespan and cost of use. In particular, for supported noble-metal catalysts with poor stability, some unique design strategies have been summarized for the efficient removal of VOCs while balancing low noble-metal usage and optimized catalytic performance. Finally, the scientific problems and future research directions are presented. Coordinated treatment of atmospheric pollutants and greenhouse gases should be considered. This study is expected to provide profound insights into the design of catalysts with high activity, selectivity, and stability, as well as air pollution control via catalytic methods.

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Synthesis of H2O2 and high-value chemicals by covalent organic framework-based photocatalysts Gaoxiong Liu, Rundong Chen, Bingquan Xia, Zhen Wu, Shantang Liu, Amin Talebian-Kiakalaieh, Jingrun Ran 2024, 61:  97-110.  DOI: 10.1016/S1872-2067(24)60014-8 Abstract ( 312 )   HTML ( 16 )   PDF (4553KB) ( 139 )   Hydrogen peroxide (H2O2) is a versatile and environmentally friendly oxidizer widely used in diverse fields. The solar-driven photocatalytic oxygen reduction reaction generates H2O2 from air and water, avoiding undesirable byproducts. This green and pollution-free route is applicable to various domains. Although extensive research covers covalent organic framework (COF)-based photocatalysts for H2O2, little attention has been paid to systems that generate high-value chemicals in the presence of scavengers. To address this gap, we systematically discuss the simultaneous photocatalytic generation of H2O2 and valuable chemicals. We emphasize the pathways for H2O2 generation using COF-based photocatalysts and highlight the role of sacrificial agents. Novel synthetic methodologies and modification strategies for enhancing the photocatalytic yield are presented. Our work aims to strengthen the identification and discussion of the challenges faced by photocatalysts in this field. This study aims to inspire further investigations and innovations in COF-based photocatalysis for sustainable and value-added chemical synthesis by presenting a holistic view.

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Recent advances in metal titanate-based piezocatalysts: Enhancing catalytic performance through improved piezoelectric properties and regulated carrier transport Kaiqi Wang, Yiming He 2024, 61:  111-134.  DOI: 10.1016/S1872-2067(23)64635-2 Abstract ( 240 )   HTML ( 15 )   PDF (8642KB) ( 83 )   Piezocatalysis, as an emerging technology, holds the promise for providing sustainable solutions to environmental remediation and energy management through mechanical energy utilization. Metal titanates (MTs) are well-known for their outstanding piezoelectric response, positioning them as the primary candidates for catalysts in this field. Moreover, their eco-friendly and cost-effective attributes have made them the focus of considerable attention among researchers. However, the insufficient piezocatalytic activity continues to constrain the practical application of MTs. Confronted with suboptimal energy conversion efficiency, enhancing the response to mechanical energy and reducing the subsequent conversion losses are pivotal for improving the piezocatalytic performance. This review commences with the classification and introduction of various MTs relevant to the field of piezocatalysis. Subsequently, the main methods for preparing MTs are presented. Particularly, the design strategies of MTs with excellent piezocatalytic properties are discussed from the perspectives of improving piezoelectric properties and regulating carrier transport, including construction of morphotropic phase boundary, strain engineering, Curie point control, external field-induced polarization, oriented crystal growth, co-catalyst loading, carbon modification, and semiconductor heterostructure construction. Finally, comprehensive challenges to the development of piezocatalytic technology are presented to promote the rational design and practical application of piezocatalysts.

Articles

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Modulation of ketyl radical reactivity to mediate the selective synthesis of coupling and carbonyl compounds Zhaohui Chen, Jun Deng, Yanmei Zheng, Wenjun Zhang, Lin Dong, Zupeng Chen 2024, 61:  135-143.  DOI: 10.1016/S1872-2067(24)60045-8 Abstract ( 318 )   HTML ( 30 )   PDF (3427KB) ( 188 )   Supporting Information The importance of selective synthesis of high-value-added chemicals from renewable resources is paramount but remains a crucial challenge in organic synthesis and chemical reformation. Herein, we report the selective photosynthesis of C-C coupling products and carbonyl compounds from biomass-derived alcohols. The key to ensuring high end-to-end selectivity is the modulation of the reactivity of ketyl radical (*RCHOH) intermediates by employing different metal co-catalysts (Au, Pt, Pd, Ru) supported on Cd0.6Zn0.4S solid solution (CZS) photocatalysts. In particular, the C-C coupling product, hydrobenzion, and fully oxidized benzaldehyde were obtained from benzyl alcohol with high selectivity (> 98%) over Au-CZS and Ru-CZS, respectively. Combined experimental and theoretical analyses demonstrated that the affinity of *RCHOH for the surface of metals governs their subsequent transformations, in which weak and strong radical adsorption on Au and Ru results in C-C coupling products and carbonyl compounds, respectively.

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A Ta3N5 photoanode with few deep-level defects derived from topologic transition of ammonium tantalum oxyfluoride for ultralow-bias photoelectrochemical water splitting Wei Xu, Chao Zhen, Huaze Zhu, Tingting Yao, Jianhang Qiu, Yan Liang, Shuo Bai, Chunlin Chen, Hui-Ming Cheng, Gang Liu 2024, 61:  144-153.  DOI: 10.1016/S1872-2067(24)60056-2 Abstract ( 114 )   HTML ( 5 )   PDF (2494KB) ( 44 )   Supporting Information An open challenge for developing solar-driven Ta3N5-based photoanodes with the ability to induce low-bias photoelectrochemical (PEC) water splitting is that their deep-level defects originated from low-valent tantalum cations (Ta3+) and nitrogen vacancies (VN) seriously reduce the photovoltage and thus increase the bias for water splitting. Herein, we developed an effective topotactic transition synthesis route of producing few deep-level defects porous Ta3N5 film from the precursor film of ammonium tantalum oxyfluoride compound ((NH4)2Ta2O3F6) pyramids on the Ta foil. The highly electronegative fluoride ions in (NH4)2Ta2O3F6 could weaken the Ta-O bonds and the accompanied porous structure facilitates reactant diffusion, which favors the complete nitridation. Consequently, the resulting porous Ta3N5 film has very few deep-level defects, enabling an ultralow photocurrent onset potential at 0.2 V (vs. RHE) and a short-circuit photocurrent density (Jsc) of 3.28 mA cm-2 after decorating oxygen evolution reaction (OER) cocatalysts under AM 1.5 G irradiation. Moreover, the Jsc can retain 85% of the initial value for a 5 h continuous stability test. By reducing the particle size of (NH4)2Ta2O3F6 pyramid precursor, the deep-level defects could be further lowered in the Ta3N5 film, achieving the photoactivity for water oxidation at 0 V (vs. RHE) after modifying the OER co-catalyst.

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Understanding the correlation between zinc speciation and coupling conversion of CO2 and n-butane on zinc/ZSM-5 catalysts Xuke Sun, Rongsheng Liu, Gaili Fan, Yuhan Liu, Fangxiu Ye, Zhengxi Yu, Zhongmin Liu 2024, 61:  154-163.  DOI: 10.1016/S1872-2067(24)60036-7 Abstract ( 159 )   HTML ( 15 )   PDF (4196KB) ( 84 )   Supporting Information The coupling reaction of alkanes and CO2 into high value-added bulk chemical products is a promising way for CO2 utilization. The Zn-introduced ZSM-5 catalyst plays an essential role in this process; however, the correlation between the catalytic performance and Zn species of the catalyst has yet to be established. Herein, the structural properties, the acid sites, and the existence status of the Zn species in the Zn-introduced catalysts were systematically characterized by several techniques. And the influence of the state of Zn species in the coupling reaction was discussed. The results indicate that the Zn species exist in the form of ZnO cluster, Zn-OH+, and (Zn-O-Zn)2+ species, thereinto (Zn-O-Zn)2+ species are produced by the Zn-OH+ group with the increasing Zn loading. The decrease of Brønsted acid sites, the formation of newly active sites caused by Zn species, and the accumulation of coarse ZnO species, are responsible for the change of n-butane conversion. The Zn-OH+ group serves as the primary catalytic center for the conversion of CO2. Both the Zn-OH+ group and the (Zn-O-Zn)2+ species enhance the dehydrogenation performance of the Zn-introduced catalysts, thereby promoting the generation of aromatics. The Zn5%-ZSM-5 sample showed the most excellent catalytic performance; the n-butane conversion was 94.71%, the CO2 conversion was 30.43%, and the aromatics selectivity was 53.71%. Simultaneously, we propose a more specific mechanism for the coupling reaction.

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Photo-thermal cooperation for the conversion of CO2 and CH4 with H2O to C2 oxygenates over SrTiOx supported CuCo Yanru Zhu, Zhijun Zhang, Jian Zhang, Shuangjiang Jiang, Zhe An, Hongyan Song, Xin Shu, Wei Xi, Lirong Zheng, Jing He 2024, 61:  164-178.  DOI: 10.1016/S1872-2067(24)60026-4 Abstract ( 164 )   HTML ( 8 )   PDF (4608KB) ( 59 )   Supporting Information Photosynthesis is a potential strategy to enable endergonic process that usually needs high-temperature in thermochemistry to supply the energy for inert-bond activation and/or strong endothermic reaction. The conversion of CO2 into value-added C2-oxygenates is a promising process to realize artificial photosynthesis, but suffers from relatively lower efficiency due to complex multi-electron (≥ 10) transfer processes and sluggish kinetics of C-C coupling. This work proposes an all-new H2O-promoted strategy for efficient production of C2 oxygenates from the concurrent activation and subsequent co-conversion of CO2 with CH4 under photo-thermal cooperation, in which photocatalytic H2O-splitting derived active hydrogen species for CO2 activation, and concomitant active oxygen species for CH4 activation. A formation rate of as high as 2.05 mmol g-1 h-1 for C2-oxygenates (CH3CHO and CH3CH2OH) in a selectivity of > 86% has been afforded over SrTiOx supported CuCo under 200 °C and ultraviolet-visible illumination. It has been revealed that SrTiOx drives photocatalytic H2O-splitting under the excitation primary from ultraviolet light, paired CuI/Cu0 sites promote the formation of *CHxO intermediate from CO2, Co sites conduct CH4-to-*CH3, and C-C coupling of *CHxO and *CH3 on adjacent Cu-Co facilitates the generation of C2-oxygenates.

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Unveiling the multiple effects of MOF-derived TiO2 on Ti-Fe2O3 photoanodes for efficient and stable photoelectrochemical water oxidation Kaikai Ba, Yuʼnan Liu, Kai Zhang, Ping Wang, Yanhong Lin, Dejun Wang, Ziheng Li, Tengfeng Xie 2024, 61:  179-191.  DOI: 10.1016/S1872-2067(24)60005-7 Abstract ( 153 )   HTML ( 7 )   PDF (4387KB) ( 44 )   Supporting Information α-Fe2O3 is a promising photoanode that is limited by its high surface charge recombination and slow water oxidation kinetics. In this study, we synthesized a TiO2 layer on Ti-Fe2O3 by annealing Ti-MOFs, followed by ZIF-67 as a co-catalyst, to fabricate a ZIF-67/TiO2/Ti-Fe2O3 photoanode for photoelectrochemical (PEC) water splitting. The systematic experimental and theoretical results revealed that the improvement in performance was due to multiple effects of the MOF-derived TiO2. This molecule not only passivates the acceptor surface states of Ti-Fe2O3, thereby reducing the number of surface recombination centers, but also acts as an electron barrier to promote charge separation in the Ti-Fe2O3 bulk. Moreover, MOF-derived TiO2 can dramatically reduce the energy barrier for the OER of Ti-Fe2O3, thus promoting the conversion of the intermediate *OH into *O. The synergistic improvement in the bulk and surface properties effectively enhanced the water oxidation performance of Ti-Fe2O3. The ZIF-67/TiO2/Ti-Fe2O3 photoanode exhibits a photocurrent density of up to 4.04 mA cm‒2 at 1.23 V vs. RHE, which is 9.4 times as that of pure Ti-Fe2O3, and has long-term stability. Our work provides a feasible strategy for constructing efficient organic-inorganic hybrid photoelectrodes.

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Constructing amorphous/crystalline NiFe-MOF@NiS heterojunction catalysts for enhanced water/seawater oxidation at large current density Xianbiao Hou, Chen Yu, Tengjia Ni, Shucong Zhang, Jian Zhou, Shuixing Dai, Lei Chu, Minghua Huang 2024, 61:  192-204.  DOI: 10.1016/S1872-2067(24)60030-6 Abstract ( 332 )   HTML ( 24 )   PDF (4422KB) ( 76 )   Supporting Information Developing metal-organic frameworks (MOF) based catalysts with high activity and chlorine corrosion resistance is of paramount importance for seawater oxidation at large current density. Herein, we report a heterogeneous structure coupling NiFe-MOF nanoparticles with NiS nanosheets onto Ni foam (denoted as the NiFe-MOF@NiS/NF) via the mild strategy involving sulfur-modified corrosion and electrodeposition treatment. The constructed amorphous/crystalline interfaces could not only facilitate the adequate infiltration of electrolyte and release of O2 bubbles at large current densities, but also significantly improve the charge transfer from NiFe-MOF to NiS and the adsorption/desorption capacity of oxygen intermediates. Intriguingly, during oxygen evolution reaction process, the sulfate film formed by the self-reconstruction could remarkably inhibit the adsorption of Cl- ions on the catalyst surface in the seawater electrolytes. Benefiting from the robust corrosion resistance, unique amorphous/crystalline interfaces, and the charge redistribution, the well-designed NiFe-MOF@NiS/NF exhibits the low overpotential of 346 and 355 mV under a high current density of 500 mA cm-2 in alkaline water and seawater electrolytes, respectively. More importantly, the as-fabricated NiFe-MOF@NiS/NF demonstrates prolonged stability and durability, lasting over 600 h at a current density of 100 mA cm-2 in both electrolytes. This study enriches the understanding of electronic structure modulation and chlorine corrosion resistance in seawater, providing broad prospects for designing advanced MOF-based catalysts.

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Enhancement of H2O2 generation rate in porphyrin photocatalysts via crystal facets regulation to create strong internal electric field Yunhang Shao, Yaning Zhang, Chaofeng Chen, Shuai Dou, Yang Lou, Yuming Dong, Yongfa Zhu, Chengsi Pan 2024, 61:  205-214.  DOI: 10.1016/S1872-2067(24)60039-2 Abstract ( 206 )   HTML ( 15 )   PDF (10389KB) ( 71 )   Supporting Information Three TCPP porphyrin-based nanosheet photocatalysts with exposed (400), (022), and (020) planes were synthesized using a dissolution-recrystallization method in a mixture of water and tetrahydrofuran (THF), methanol (MeOH), and ethylene glycol (EG). The TCPP photocatalyst with the exposed (400) surface exhibited the highest H2O2 production rate of 29.33 mmol L‒1 h‒1 g‒1 from only H2O and O2, surpassing the rates observed for ones with exposed (022) and (020) surfaces by factors of 2.7 and 4.1, respectively, and 1.3 times as that of the reported TCPP prepared by a base/acid self-assembling method. This enhancement can be attributed to the strong internal electric field and high carboxyl group content on the (400) surface, which hindered rapid charge recombination and facilitated challenging water oxidation. Hence, successful manipulation of porphyrin exposure to robust IEF planes enhances the photocatalytic activity of the system and provides valuable insights for the design and development of more efficient organic photocatalysts.

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Nano-MnO2 anchored on exfoliated MXene with exceptional and stable Fenton oxidation performance for organic micropollutants Tao Wen, Sisheng Guo, Hengxin Zhao, Yuqi Zheng, Xinyue Zhang, Pengcheng Gu, Sai Zhang, Yuejie Ai, Xiangke Wang 2024, 61:  215-225.  DOI: 10.1016/S1872-2067(24)60041-0 Abstract ( 269 )   HTML ( 6 )   PDF (12901KB) ( 88 )   Supporting Information Peroxymonosulfate (PMS) Fenton-like systems have emerged as promising alternatives to hydrogen peroxide (H2O2). Fenton systems are currently used in the industry owing to their highly efficient utilization rate of oxidizing agents and wide operating pH ranges. Heterogeneous Fenton-like catalysts are promising candidates in this regard. However, self-aggregation and generation of ambiguous reactive oxygen species greatly restrict their broad application in practical settings. Herein, a redox reaction between exfoliated MXene and KMnO4 facilitates the in-situ deposition of MnO2 nanoparticles on the surface of Ti-deficient vacancies of MXene (MXene/MnO2). Owing to the advantages of MXene with fast charge transfer and MnO2 with strong PMS activation ability, the engineered MXene/MnO2@PVDF catalytic membrane exhibited enhanced activity and excellent long-term stability for various refractory organic pollutants. Experimental observations, combined with density functional theory calculations, revealed that the exposed Mn sites effectively promoted the generation of 1O2. Interestingly, the widespread pathway for the direct generation of 1O2 via high-valent Mn-oxo phases has a high energy barrier (3.34 eV). In contrast, the pathway that uses the •OOH species as intermediates to produce 1O2 is energetically more viable (1.84 eV). This work offers insights into the in-situ engineering of transition metal-oxides on MXene-based membranes, facilitating their implementation in remediating micropollutant-contaminated environmental water.

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Phase engineering of Ru-based nanocatalysts for enhanced activity toward CO2 methanation Chongya Yang, Weijue Wang, Hongying Zhuo, Zheng Shen, Tianyu Zhang, Xiaofeng Yang, Yanqiang Huang 2024, 61:  226-236.  DOI: 10.1016/S1872-2067(24)60055-0 Abstract ( 186 )   HTML ( 14 )   PDF (5427KB) ( 46 )   Supporting Information The catalytic behavior of metal nanocatalysts is intrinsically contingent on the diversity of their exposed surfaces, which can be substantially regulated through the phase engineering of metal nanoparticles. In this study, it is demonstrated that the face-centered cubic (fcc) phase Ru with a close-packed (111) surface presents superior catalytic activity towards CO2 methanation. This behavior is attributed to its enhanced capability toward CO2 chemisorption derived from its inherently high surface reactivity. Complete exposure of such surfaces was successfully achieved experimentally by the synthesis of icosahedral Ru metal nanoparticles, which exhibited remarkable performance for CO2 methanation with 5-8 times higher activity than its conventional hexagonal close-packed (hcp) counterpart when supported on inert supports. However, for the joined fcc-Ru nanoparticles in the fresh catalyst, an fcc- to hcp-phase transformation was observed at a relatively high temperature with the in situ characterizations, which resulted in metal agglomeration and led to catalyst deactivation. However, the CO2 conversion was still much higher than that of the hcp-phase Ru nanocatalysts, as the monodispersed particles could maintain their fcc phase. Our results demonstrate that phase engineering of Ru nanocatalysts is an effective strategy for a catalyst design with improved catalytic performance. However, the phase transformation could represent a latent instability of the catalysts, which should be considered for the further development of robust catalysts.

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In-situ construction of three-dimensional ordered cobalt-nitrogen- carbon nanotubes integrated self-supporting electrode for efficiently electrocatalyzing oxygen reduction reaction Rui Chen, Xiang Fang, Dongfang Zhang, Lanqi He, Yinlong Wu, Chenghua Sun, Kun Wang, Shuqin Song 2024, 61:  237-246.  DOI: 10.1016/S1872-2067(24)60023-9 Abstract ( 201 )   HTML ( 11 )   PDF (11061KB) ( 70 )   Supporting Information Developing low-cost non-precious metal catalysts (NPMC) to replace Pt-based catalysts and rationally designing their integrated electrode to efficiently electrocatalyze oxygen reduction reaction (ORR) are greatly significant for facilitating the commercialization of fuel cells. Here, we report a novel self-supporting three-dimensional (3D) ordered integrated ORR electrode by a simple chemical vapor deposition (CVD) approach to in-situ grow Co,N co-doped carbon nanotubes (N-CNTs@Co) onto carbon paper modified by oxygen-containing functional groups (OCP). Benefiting from the moderate density of CNTs and abundant pyridinic N and graphitic N configurations as ORR active sites, the best-performing sample (N-CNTs-20@Co/OCP) exhibits outstanding ORR performance in both basic (0.1 mol L‒1 KOH) and acidic (0.1 mol L‒1 HClO4) media, which is comparable to the one fabricated through the conventional method by spraying commercial Pt/C (20 wt%) onto OCP substrate (0.2 mg Pt cm‒2). This work can provide a feasible solution for the in-situ construction of efficient NPMC-based ORR integrated electrode.

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Defect-induced in situ electron-metal-support interactions on MOFs accelerating Fe(III) reduction for high-efficiency Fenton reactions Haifang Mao, Yang Liu, Zhenmin Xu, Zhenfeng Bian 2024, 61:  247-258.  DOI: 10.1016/S1872-2067(24)60047-1 Abstract ( 216 )   HTML ( 8 )   PDF (6600KB) ( 119 )   Supporting Information The inefficient reduction of Fe3+ and activation of H2O2 in the Fenton reaction severely limit its application in practical water treatment. In this study, we developed defective NH2-UiO-66 (d-NU) with coordinated unsaturated metal sites by adjusting the coordination configuration of Zr, creating a solid-liquid interface to facilitate Fe3+ reduction and the sustainable generation of •OH from H2O2 activation. The d-NU/Fe3+/H2O2/Vis system demonstrated highly efficient removal of various organic pollutants, with a rapid Fe2+ regeneration rate and exceptional stability over ten cycles. The degradation rate constant of d-NU (0.16112 min-1) was 11 times higher than that of NH2-UiO-66 (NU) (0.01466 min-1) without defects. Characterization combined with density functional calculations revealed that defects induced coordination unsaturation of the Zr sites, leading to in situ electron-metal-support interactions between Fe3+ and the support via Zr-O-Fe bridges. This accumulation of electrons from the unsaturated Zr sites enabled the adsorption of Fe3+ at the solid-liquid interface, promoting the formation of Fe2+ across a wide pH range with a reduced energy barrier. This study introduces a promising strategy for accelerating Fe3+ reduction in the solid-liquid interfacial Fenton process for the degradation of organic pollutants.

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Spontaneous dispersion of metallic nickel centers in inert metal substrate for the selective hydrogenation of carbon-carbon triple bonds Xin Deng, Caiyan Zheng, Weijie Li, Jiamin Wang, Di Yang, Zhenpeng Hu, Landong Li 2024, 61:  259-268.  DOI: 10.1016/S1872-2067(24)60048-3 Abstract ( 141 )   HTML ( 7 )   PDF (3841KB) ( 49 )   Supporting Information Single-site metal catalysts with maximal utilization of active centers and desired target product selectivity represent a hot research topic within the realms of both academic and industry. However, the synthetic strategy is generally complicated and requires the precise control of interplay between metal centers and supporting materials. Herein, a simple spontaneous dispersion and universal strategy are developed to construct all-metal catalyst systems containing isolated metallic centers utilizing the spontaneous dispersion behaviors of transition metal centers Ni in inert substrate (Al, Mg and Ti). Ni/Al and Ni/Mg show remarkable performances in the model reaction of acetylene semi-hydrogenation with state-of-the-art site-specific activity, high ethylene selectivity and good stability. Especially, Ni/Al is reported for the first time to be an eligible low-cost catalyst for the selective hydrogenation of carbon-carbon triple bonds, surpassing the benchmark Lindlar catalyst. The reaction mechanism of acetylene semi-hydrogenation over Ni/Al catalyst is well clarified via the combination of kinetic analyses, spectroscopy investigation and theoretical calculations. The innovative approach developed herein not only expands the synthetic strategies toward single-site metal catalysts but also holds promise for practical applications in diverse chemical transformations due to the intrinsic advantages of all-metal systems.

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In situ surface reconstruction of heterostructure Ni2P/CoP/FeP4 nanowires network catalyst for high-current-density overall water splitting Ting Zhao, Bingbing Gong, Guancheng Xu, Jiahui Jiang, Li Zhang 2024, 61:  269-280.  DOI: 10.1016/S1872-2067(24)60037-9 Abstract ( 246 )   HTML ( 14 )   PDF (5298KB) ( 94 )   Supporting Information Considering the imperative need for cost-effective electrocatalysts for water electrolysis, a novel Ni2P/CoP/FeP4/IF electrocatalyst nanowires network was synthesized in this study. Owing to the strong synergistic effects and high exposure of the active sites, Ni2P/CoP/FeP4/IF exhibited exceptional performance in both the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), demonstrating low overpotentials of 218 and 127 mV at 100 mA cm-2 in alkaline media, respectively. Furthermore, the water electrolyzer based on Ni2P/CoP/FeP4/IF bifunctional catalyst requires only 1.50 and 2.05 V to reach 10 and 500 mA cm-2, respectively, indicating its potential for large-scale hydrogen production. Comprehensive ex situ characterizations and in situ Raman spectra reveal that Ni2P/CoP/FeP4/IF undergoes rapid reconstruction during the OER to form the corresponding (oxy) hydroxide species, which serve as the real active sites. Furthermore, density functional theory calculations clarified that during the HER process, H2O is adsorbed at the Fe site of Ni2P/CoP/FeP4/IF for hydrolysis, with the resultant H* adsorbed at the Ni site for desorption. Introducing CoP promoted water adsorption and increased the HER activity of the catalyst. Hence, this study offers a pathway for designing highly efficient catalysts that leverage the interface effects.

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Atomically tailoring synergistic active centers on molybdenum sulfide basal planes for alkaline hydrogen generation Xuyu Luo, Ying Wang, Guang Yang, Lu Liu, Shiying Guo, Yi Cui, Xiaoyong Xu 2024, 61:  281-290.  DOI: 10.1016/S1872-2067(24)60034-3 Abstract ( 138 )   HTML ( 7 )   PDF (2894KB) ( 43 )   Supporting Information Alkaline water electrolysis allows the adoption of non-precious metal catalysts, but increases the challenge of cathodic hydrogen evolution reaction (HER) with the proton-deficient environment. Here we report an “all-in-one” design by atomic-level tailoring on molybdenum sulfide (MoS2) basal planes with synergistic active centers to trigger water dissociation for proton supply and meanwhile improve proton adsorption for hydrogen evolution. The resultant Co/O-codoped MoS2 (Co-O@MoS2) catalyst shows superb alkaline HER activity with a small Tafel slope of 42 mV dec-1 and an overpotential as low as 81 mV at 100 mA cm-2, and considerable stability over 300 h even at industrial-grade high current density of 600 mA cm-2, which are among the best records for precious-metal-free HER catalysts in alkaline media. The markedly enhanced alkaline HER performance is attributed to the synergistic effect from atomically constructed O-Co-S2 motifs with local electronic interactions, in which Co sites promote the premier water dissociation, and S sites facilitate proton transition to generate hydrogen, respectively. This work presents an atomic-scale structural modification to create synergistic active sites for alkaline HER and provides insights into the atomic activation engineering towards advanced catalysts.

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Photoredox cobalt-catalyzed stereodivergent synthesis of 1,4-dienes Xing-Yu Ren, Jia-Jun Liu, Shi-Qi Zhang, Yan-Lin Li, Kun Cui, Jing Li, Zheng-Yang Gu, Ji-Bao Xia 2024, 61:  291-300.  DOI: 10.1016/S1872-2067(24)60031-8 Abstract ( 159 )   HTML ( 13 )   PDF (1109KB) ( 64 )   1,4-Dienes are important scaffolds widely used in natural products and medicinal compounds. Herein, we report a highly efficient method for the straightforward synthesis of 1,4-dienes via regio- and stereoselective reductive coupling of alkynes and allenes, catalyzed by visible-light photoredox cobalt. In contrast to the conventional E-alkene products, both (Z,E)- and (E,E)-1,4-dienes were synthesized with good regio- and stereoselectivities under mild conditions. In this photoredox reaction, Hünig’s base and water were utilized as hydrogen sources instead of the commonly used Hantzsch esters. The mechanistic and density functional theory studies indicate that the reaction undergoes protolysis of a cobaltacyclopentene intermediate and photocatalytic E→Z isomerization of (E,E)-1,4-dienes to (Z,E)-1,4-dienes via an energy transfer process.

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Mechanistic insights and the role of spatial confinement in catalytic dimethyl ether carbonylation over SSZ-13 zeolite Xiaomin Zhang, Kai Cai, Ying Li, Ji Qi, Yue Wang, Yunduo Liu, Mei-Yan Wang, Shouying Huang, Xinbin Ma 2024, 61:  301-311.  DOI: 10.1016/S1872-2067(24)60040-9 Abstract ( 237 )   HTML ( 11 )   PDF (4047KB) ( 98 )   Supporting Information The SSZ-13 zeolite, which exhibits typical CHA topology characterized by 8-membered ring (8-MR) channels, has shown potential for catalyzing dimethyl ether (DME) carbonylation. However, current studies have yet to provide a comprehensive analysis of its catalytic mechanisms. In this study, we investigated the mechanism of SSZ-13-catalyzed DME carbonylation and the role of spatial confinement in this reaction. By exploiting the differences in the radii of the metal ions, we selectively replaced Brønsted acid sites (BAS) within specific channels, as confirmed by quantitative acidity analysis. Combining the activity data and the dissociation energies of the reactants on the BAS within different rings, we found that both the main and side reactions of DME carbonylation occurred on the 8-MR BAS of SSZ-13. Furthermore, the exchange of ions of different radii highlighted the confinement effect of the pore space in the SSZ-13 zeolite. Characterization of the deposits in spent catalysts, along with theoretical insights, revealed that the reduced cage space adversely affects the stabilization of side reaction intermediates, which in turn mitigates side reactions and improves the selectivity toward methyl acetate. This study presents an effective approach to modulate the acid site distribution and spatial confinement and provides critical insights into the determinants of the catalytic performance of SSZ-13. These findings offer valuable guidance for the future design and optimization of zeolites, aiming to enhance their efficacy in catalytic applications.

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Near-unity photocatalytic dehydrocoupling of thiophenols into disulfides and hydrogen using coupled CdS Nanorods and Ni-containing polyoxometalate Mengzhen Ren, Tianfu Liu, Yuanyuan Dong, Zheng Li, Jiaxin Yang, Zhenheng Diao, Hongjin Lv, Guo-Yu Yang 2024, 61:  312-321.  DOI: 10.1016/S1872-2067(24)60025-2 Abstract ( 240 )   HTML ( 53 )   PDF (5757KB) ( 83 )   Supporting Information Simultaneously harnessing the photogenerated electrons and holes to convert thiols into the value-added disulfides with the concomitant formation of H2 represents a highly promising strategy for maximizing the conversion of solar energy into chemical energy. Herein, we report an effective catalytic system comprising CdS nanorods (NRs) and Ni-containing polyoxometalate (Na6K4[Ni4(H2O)2(PW9O34)2] (Ni4P2)) (Ni4P2/CdS), which exhibited efficient photocatalytic activities towards the near-unity dehydrocoupling of 4-methoxythiophenol (4-MTP) into disulfide and H2 evolution. The photooxidative dehydrocoupling of 4-MTP can be finished after 4 h photocatalysis, leading to 98.39% conversion of 4-MTP with the yield of disulfide and H2 reaching 24.45 and 25.96 μmol, respectively. The Ni4P2/CdS catalytic system also showed good photocatalytic recycling stability. Comprehensive experimental and characterization results indicated that the synergistic cooperation between CdS NRs and Ni4P2 facilitated the separation and migration of the photogenerated electron-hole pairs, thereby improving the photocatalytic dehydrocoupling of 4-MTP to disulfide coupling with hydrogen production.

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Solvent-scissors overcoming inert hydrogen bonding enable efficient oxidation of aromatic hydrocarbons under atmospheric oxygen Kui Jin, Meiyun Zhang, Penghua Che, Dongru Sun, Yong Wang, Hong Ma, Qiaohong Zhang, Chen Chen, Jie Xu 2024, 61:  322-330.  DOI: 10.1016/S1872-2067(24)60042-2 Abstract ( 154 )   HTML ( 6 )   PDF (9373KB) ( 48 )   Supporting Information Hydrogen bonding is a fascinating interaction that controls the outcomes of chemical reactions. However, overcoming the strong deactivation arising from alterations in the polarity and electronic properties of the reactants and intermediates remains a challenge. Herein, we proposed a “solvent-scissors” strategy for overcoming the inert hydrogen bonding, enabling the efficient aerobic oxidation of methyl aromatics into aromatic acids under atmospheric oxygen at 25‒45 °C. The hydrogen bonds between the key intermediate, benzaldehyde (PhCHO), and hexafluoroisopropanol (HFIP) were reconstructed using solvent-scissors (acetic acid (HOAc), ethyl acetate, ethyl chloroacetate, and methyl chloroacetate), which promoted the release of free PhCHO from its inert hydrogen-bonded state and enabled the one-step oxidation of toluene to benzoic acid under mild conditions. The standard Gibbs free energy changes (ΔG0) representing the proton acceptance capability of the solvent were of the same order of magnitude as the turnover number (TON) (capacity for promoting benzaldehyde oxidation). This approach affords remarkable benzoic acid selectivity (98.7%) with high toluene conversion (96.8%) at 45 °C within 4 h under 0.1 MPa O2 using NHPI/metal acetate/HFIP-HOAc. This strategy opens up a new avenue for regulating hydrogen bonding in a wider range of applications for the planning and development of synthesis protocols.