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Chinese Journal of Catalysis
2023, Vol. 48
Online: 18 May 2023

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Cover: Professor Chun-Ran Chang and coworkers revealed the reaction mechanism of nonoxidative coupling of methane (NOCM) on Cu surface-dispersed Pt single-atom sites (SASs) and single-cluster sites (SCSs) by using the combination of DFT calculations and microkinetic modeling, and predicted that Pt SASs have more advantages than SCSs in the NOCM. Read more about the article behind the cover on page 90–100.

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Strategies for local electronic structure engineering of two-dimensional electrocatalysts Cheng-Feng Du, Erhai Hu, Hong Yu, Qingyu Yan 2023, 48:  1-14.  DOI: 10.1016/S1872-2067(23)64423-7 Abstract ( 373 )   HTML ( 37 )   PDF (5941KB) ( 431 )   Electrocatalytic processes have garnered increased attention for energy conversion and mass production because of their high efficiency and selectivity. In particular, electrocatalysts play a critical role in catalytic performance. Two-dimensional (2D) materials, which feature a large surface area with abundant active sites and tunable physicochemical properties, have been regarded as one of the most important candidates for future electrocatalysis. However, further research efforts are required to specifically optimize their catalytic performance to realize their commercialization. In this account, strategies for regulating the local electronic structures of 2D electrocatalysts, including heteroatom doping, single-atom loading, heterojunction formation, vacancy engineering, and strain engineering, are briefly summarized. Furthermore, the relationship between these strategies and the electrocatalytic performance of the developed materials is discussed. Finally, an outlook of the 2D electrocatalysts is provided.

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Carbon-based catalysts of the oxygen reduction reaction: Mechanistic understanding and porous structures Wenjing Zhang, Jing Li, Zidong Wei 2023, 48:  15-31.  DOI: 10.1016/S1872-2067(23)64427-4 Abstract ( 748 )   HTML ( 43 )   PDF (20708KB) ( 674 )   Carbon-based catalysts are potential substitutes for noble-metal catalysts in the oxygen reduction reaction (ORR) owing to their excellent electrical conductivities and chemical stabilities. To rationally design and accelerate the identification of highly efficient carbon-based ORR catalysts, improving the design of the active sites and microstructures is necessary. In this review, strategies for improving the intrinsic performances, activities, stabilities, and anti-poisoning properties of catalysts are analyzed. As a critical component of the microstructure, the porous structures of catalysts significantly affect their distributions of active sites and levels of mass transfer, which are also extensively analyzed. Finally, based on the formation of active sites and the fabrication of porous structures, conclusions and perspectives regarding the future development of highly efficient carbon-based electrocatalysts are provided.

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Efficient strategies for promoting the electrochemical reduction of CO2 to C2+ products over Cu-based catalysts Huanhuan Yang, Shiying Li, Qun Xu 2023, 48:  32-65.  DOI: 10.1016/S1872-2067(23)64429-8 Abstract ( 1138 )   HTML ( 79 )   PDF (8560KB) ( 999 )   Cu-based catalysts have been widely studied for the electrochemical CO2 reduction reaction (CO2RR) to yield high-value-added products with two or more carbons (C2+ products). The rational design of Cu-based catalysts is critical to improve the selectivity and energy efficiency of the CO2RR-to-C2+ process. Herein, we review recent advances in Cu-based catalysts with surface modification for four crucial factors in CO2RR-to-C2+ based on briefly analyzing the reaction mechanisms: (1) surface hydrophobization to inhibit the hydrogen evolution reaction; (2) introduction of CO2-capture materials, halide-ion doping, and Cuδ+/Cu0 synergy to promote CO2 adsorption and activation; (3) bifunctional catalysts and locally enhanced electric-thermal fields for modulating CO generation and adsorption; and (4) development of confinement structures and heterostructures, addition of oxidation states or defects, and use of single-atoms with different coordination environments to promote carbon-carbon coupling. In particular, the relationships between the surface properties of Cu-based catalysts and improved activity and C2+ selectivity in CO2RR are discussed, along with strategies for enhancing the stability of the catalyst. Furthermore, the current challenges and potential strategies for future CO2RR-to-C2+ research are discussed in this review.

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High-temperature shock synthesis of high-entropy-alloy nanoparticles for catalysis Yanchang Liu, Xinlong Tian, Ye-Chuang Han, Yanan Chen, Wenbin Hu 2023, 48:  66-89.  DOI: 10.1016/S1872-2067(23)64428-6 Abstract ( 762 )   HTML ( 61 )   PDF (14095KB) ( 856 )   Rational design and precise fabrication of advanced functional materials are intimately linked to the technological advances in synthetic methodologies. The high-temperature shock (HTS) method, which involves an ultrafast heating/cooling rate (>105 K s-1) and features kinetics-dominated characteristics in material synthesis, exhibits high superiority in exploring and controllable preparation of novel materials that are typically unobtainable, such as high-entropy composition, thermodynamically metastable phases, and defect-rich surfaces. Among these significant advances, high-entropy alloy (HEA) nanoparticles are particularly prominent in heterogeneous catalytic reactions with remarkable activity, selectivity, and stability owing to their flexible composition space and high-entropy mixing structure. In this review, the physicochemical principles of HTS are presented, and the equipment and mechanisms of representative HTS techniques (e.g., Joule heating, laser heating, microwave heating) are comprehensively introduced, with the aim of accelerating the development of burgeoning HTS techniques. The concept and features of HEAs are also briefly introduced, and recent progress in the synthesis of HEAs using the HTS techniques is reviewed to provide a focused view on the unique advantages of HTS synthesis for HEAs and the exploration of novel materials. Finally, conclusions and perspectives are also provided for future investigations of HTS and HEAs, which have great significance in guiding their development and integrating their strengths.

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Mechanistic and microkinetic study of nonoxidative coupling of methane on Pt-Cu alloy catalysts: From single-atom sites to single-cluster sites Zheng-Qing Huang, Shu-Yue He, Tao Ban, Xin Gao, Yun-Hua Xu, Chun-Ran Chang 2023, 48:  90-100.  DOI: 10.1016/S1872-2067(23)64408-0 Abstract ( 354 )   HTML ( 22 )   PDF (3940KB) ( 250 )   Supporting Information Desirable catalysts possessing the ability to selectively break C-H bond and controllably catalyze C-C bond formation are highly demanded for the nonoxidative coupling of methane (NOCM). Herein, a series of Pt-Cu alloy catalysts including Pt1©Cu(111), Pt2©Cu(111) and Pt3©Cu(111) are deliberately designed and systematically studied for NOCM. Density functional theory calculations reveal that the Pt1, Pt2, and Pt3 sites on Cu(111) can selectively break the C-H bond to generate CH3, CH2, and CH species, respectively. However, direct coupling of corresponding CHx (x = 3, 2, 1) to form C2H6, C2H4, and C2H2 are favorable on Pt3, Pt1, and Pt2 sites on Cu(111), respectively. The different reactivity trends of the three Pt sites mainly originate from the varying bonding abilities of CHx species at the Pt sites. Microkinetic modeling manifests that the Pt1©Cu(111) is the most active for methane dissociation (TOF = 2.98 s-1 at 1000 K) and can selectively convert methane into ethylene with the highest selectivity up to 96.2% at 750 K. Moreover, Pt1©Cu(111) also shows superb stability under reaction conditions. Overall, our studies not only provide a comprehensive understanding of the reaction mechanism of NOCM on Pt single-atom sites (SASs) and Pt single-cluster sites (SCSs) but also predict that Pt SASs are advantageous over Pt SCSs for NOCM.

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Elucidating coke formation and evolution in the catalytic steam reforming of biomass pyrolysis volatiles at different fixed bed locations Enara Fernandez, Laura Santamaria, Irati García, Maider Amutio, Maite Artetxe, Gartzen Lopez, Javier Bilbao, Martin Olazar 2023, 48:  101-116.  DOI: 10.1016/S1872-2067(23)64407-9 Abstract ( 166 )   HTML ( 13 )   PDF (4308KB) ( 115 )   Supporting Information The evolution and the main mechanisms of catalyst deactivation have been assessed throughout continuous operation in the steam reforming of biomass pyrolysis volatiles. Biomass pyrolysis was conducted in a conical spouted bed reactor at 500 °C and the subsequent reforming step in a fixed bed reactor at 600 °C. The influence of catalyst location on the reforming reactor is also analyzed at different axial positions. Deactivated samples have been characterized by N2 adsorption-desorption, XRD, SEM and TEM images, TPO, Raman and FTIR spectroscopies. Coke deposition is the main cause of initial catalyst decay, with no sintering or oxidation of Ni sites being observed. As reaction proceeds, a deactivation front is observed along the reforming catalytic bed, with coke location within the catalyst, and its nature and composition depending on the volatile composition reaching each axial position in the bed. At the inlet section of the catalytic bed (A1), the coke is deposited on Ni sites and is of rather oxygenated nature. At further axial bed locations, the catalyst is in contact with a volatile stream whose composition has been considerably modified, which leads to the formation of a more structured coke with higher graphitization degree and made up of more condensed polyaromatic compounds. Moreover, the coke deposited on all deactivated samples does not present any specific morphology, which is evidence of its amorphous structure regardless the bed location and reaction time.

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Precise design of nickel phthalocyanine molecular structure: Optimizing electronic and spatial effects for remarkable electrocatalytic CO2 reduction Jingjing Li, Fengwei Zhang, Xinyu Zhan, Hefang Guo, Han Zhang, Wen-Yan Zan, Zhenyu Sun, Xian-Ming Zhang 2023, 48:  117-126.  DOI: 10.1016/S1872-2067(23)64412-2 Abstract ( 268 )   HTML ( 22 )   PDF (10931KB) ( 316 )   Supporting Information The atomic dispersion offered by transition metal-nitrogen-carbon electrocatalysts (M-N-C) represents a promising system for efficient catalysis of the CO2 reduction reaction (CO2RR) to a CO product. However, accurate elucidation of the catalytic mechanism of M-N-C catalysts synthesized by pyrolysis is impeded by the ambiguity of the coordination environment of the MNx active site. Herein, by combining theoretical and experimental methods, the influence of the electronic and geometric effects of the NiN4 site in a group of nickel phthalocyanine (NiPc)-based molecular catalysts on the performance of CO2RR are investigated. Density functional theory calculations indicate that only electron-withdrawing and ortho-nitro-substituted NiPc-based molecularly dispersed electrocatalysts can significantly enhance the NiN4 active site for CO2 activation. The lowest activation energy is required for forming the *COOH intermediate compared to other reference catalysts. Our modeling is in complete accordance with our experimental results, proving that the position of the substituent groups and push-pull electron effects simultaneously play crucial roles in CO2RR catalyst performance.

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Microenvironment regulation of Ru(bda)L2 catalyst incorporated in metal-organic framework for effective photo-driven water oxidation Jianxin Feng, Xuan Li, Yucheng Luo, Zhifang Su, Maoling Zhong, Baolan Yu, Jianying Shi 2023, 48:  127-136.  DOI: 10.1016/S1872-2067(23)64411-0 Abstract ( 236 )   HTML ( 10 )   PDF (9091KB) ( 283 )   Supporting Information A Ru(bda)L2 molecular catalyst (H2bda = 2,2′-bipyridine-6,6′-dicarboxylic acid, L represents ligands) was incorporated into a UiO-66 metal-organic framework (MOF) as isolating sites for chemical- and photo-driven water oxidation with the water nucleophilic attack mechanism. An impressive turn-over number of 566 was obtained for photo-driven water oxidation in the phosphate buffer saline, which was nearly 20 times that of the homogenous counterpart in the presence of ruthenium tris(bipyridine) and sodium persulfate. Infrared spectroscopy, X-ray diffraction and X-ray spectroscopy techniques were used to characterize the composition and structure of the catalysts. Kinetic isotope effect (KIE), proton inventory experiment and proton nuclear magnetic resonance were conducted to understand the photo-driven O2 evolution mechanism. It was observed that the protons participated in O2 evolution with a normal KIE value, and the uptake of phosphates by UiO-66 matrix improved the affinity towards H2O via hydrogen bonding. The high O2 output and the limited photosensitizer oxidative decomposition in PBS suggest that the phosphate acted as a proton mediator to assist proton and/or proton-couple electron transfer through a hydrogen-bonded network of water molecules. This study uses a heterogenous matrix to emulate an enzyme-like microenvironment capable of achieving efficient artificial photosynthesis.

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Benzimidazole-based covalent organic framework embedding single-atom Pt sites for visible-light-driven photocatalytic hydrogen evolution Fangpei Ma, Qingping Tang, Shibo Xi, Guoqing Li, Tao Chen, Xingchen Ling, Yinong Lyu, Yunpeng Liu, Xiaolong Zhao, Yu Zhou, Jun Wang 2023, 48:  137-149.  DOI: 10.1016/S1872-2067(23)64422-5 Abstract ( 293 )   HTML ( 21 )   PDF (1879KB) ( 329 )   Supporting Information Visible-light-driven photocatalytic hydrogen evolution reaction (HER) over a semiconductor provides an effective avenue to produce renewable clean energy and alleviate energy and environmental crises. However, the HER efficiency is still limited by the sluggish electron transfer process. Herein, a highly active covalent organic framework (COF) was constructed from the unusual benzimidazole monomer in a microwave-assisted solvothermal pathway. With single-atom Pt sites as cocatalyst, the catalyst exhibited an HER rate up to 115 mmol g-1 h-1 and a high turnover frequency of 4475.1 h-1 under visible-light irradiation. The above performance relied on the combination of benzimidazole moieties and COF framework, which, on the one hand, stabilized photogenerated electrons to prolong the electron lifetime, and on the other hand provided a strong host-guest interaction that resulted in the creation of single-atom Pt sites and the acceleration of the electron-transfer to the active sites for proton reduction. This work demonstrates the perspective of electron stabilization and interfacial charge transfer avenue construction in the HER process, which can be reached by a molecular-level design of COF-based organic semiconductors by using structural and functional diverse asymmetric building blocks.

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Tuning cobalt carbide wettability environment for Fischer-Tropsch to olefins with high carbon efficiency Peigong Liu, Tiejun Lin, Lei Guo, Xiaozhe Liu, Kun Gong, Taizhen Yao, Yunlei An, Liangshu Zhong 2023, 48:  150-163.  DOI: 10.1016/S1872-2067(23)64410-9 Abstract ( 186 )   HTML ( 8 )   PDF (5197KB) ( 1241 )   Supporting Information Fischer-Tropsch synthesis to olefins (FTO) with high carbon efficiency is an important but challenging research target. Current routes for direct syngas conversion to olefins suffer from high CO2 selectivity and low olefin yields due to the inevitable water-gas shift (WGS) reaction. Herein, we report that product selectivity can be controlled by tuning the wettability of the environment around the active center through simple physical mixing of cobalt carbide (Co2C) with a hydrophobic SiO2 component. The suppressed WGS reactivity results in a greatly improved catalytic performance of Co2C, significantly decreased CO2 selectivity (from 47.8% to 16.8%), and increased olefin selectivity (by ~65%) and activity (by 30%). The local hydrophobic environment favors the rapid diffusion of water away from the Co2C active center, thus remarkably enhancing the linear adsorption of CO and suppressing the production of CO2 via WGS. This work provides a simple yet effective strategy to modulate the product selectivity and improve the carbon efficiency of the FTO process.

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Sn1Pt single-atom alloy evolved stable PtSn/nano-Al2O3 catalyst for propane dehydrogenation Yanan Xing, Leilei Kang, Jingyuan Ma, Qike Jiang, Yang Su, Shengxin Zhang, Xiaoyan Xu, Lin Li, Aiqin Wang, Zhi-Pan Liu, Sicong Ma, Xiao Yan Liu, Tao Zhang 2023, 48:  164-174.  DOI: 10.1016/S1872-2067(23)64402-X Abstract ( 324 )   HTML ( 17 )   PDF (5811KB) ( 408 )   Supporting Information The PtSn/Al2O3 is a prototypical industrial catalyst for propane dehydrogenation (PDH). However, the local structures of the active sites are still inconclusive under the operation conditions. Herein, the evolutions of the Pt-Sn active centers supported on nano-Al2O3 are definitely discerned at the atomic level during PDH reaction. By combining complementary in situ characterizations and theoretical calculations, we demonstrate that a highly productive Sn1Pt single-atom alloy (47.6 molC3H6 gPt-1 h-1) forms after the reduction, and thereby self-assembles to the Pt3Sn intermetallic compound during the reaction, which exhibits a rather stable performance (kd-10~40h: 0.0026 h-1). Intriguingly, the results of in situ diffuse reflectance infrared Fourier-transform spectroscopy further corroborate that the adjacent Pt atoms with terrace sites aggravating the coke deposition can be circumvented through this single-atom alloy mediated reconstruction. Our findings depict an unprecedented evolution process of the active sites of the PtSn/Al2O3, and afford an effectual nanostructure engineering pathway for stable PDH catalysts.

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Facile synthesis of CoSi alloy catalysts with rich vacancies for base- and solvent-free aerobic oxidation of aromatic alcohols Zhiyue Zhao, Zhiwei Jiang, Yizhe Huang, Mebrouka Boubeche, Valentina G. Matveeva, Hector F. Garces, Huixia Luo, Kai Yan 2023, 48:  175-184.  DOI: 10.1016/S1872-2067(23)64418-3 Abstract ( 199 )   HTML ( 8 )   PDF (9695KB) ( 250 )   Supporting Information The rational design and green synthesis of low-cost, robust, and efficient catalysts for the selective oxidation of various alcohols are highly challenging. Herein, we report a fast and solvent-free arc-melting (AM) method to controllably synthesize a semimetallic CoSi alloy catalyst (denoted as AM-CoSi) that is efficient in the base- and solvent-free oxidation of six types of aromatic alcohols. X-ray absorption fine structure analysis, electron paramagnetic resonance spectroscopy, and aberration-corrected high angle annular dark field scanning transmission electron microscopy confirmed the successful synthesis of AM-CoSi with abundant Si vacancies (Siv). The as-prepared CoSi alloy catalysts exhibit an order of magnitude greater activity in the oxidation of a model reactant, benzyl alcohol (BAL) to benzyl benzoate (BBE), compared with their mono-counterparts, and provide 70% yield of BBE, the highest yield reported to date. Experimental results and density functional theory calculations suggest that the CoSi alloy structure improves the BAL conversion and that Si vacancy is the main contributor to the generation of BBE, based on which a potential reaction pathway is rationally proposed. Furthermore, the CoSi alloy maintains high stability and also exhibits high activity in the selective oxidation of various alcohols with different functional groups. This work demonstrates for the first time that semimetallic CoSi alloys can be robust catalysts for the green oxidation of various alcohols and proviedes a vast opportunity for the rational design and application of other semimetal alloy catalysts.

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Fe nanoparticles embedded in N-doped porous carbon for enhanced electrocatalytic CO2 reduction and Zn-CO2 battery Wenqian Yang, Ziqian Xue, Jun Yang, Jiahui Xian, Qinglin Liu, Yanan Fan, Kai Zheng, Peiqin Liao, Hui Su, Qinghua Liu, Guangqin Li, Cheng-Yong Su 2023, 48:  185-194.  DOI: 10.1016/S1872-2067(23)64415-8 Abstract ( 281 )   HTML ( 15 )   PDF (9526KB) ( 389 )   Supporting Information The selective electrochemical reduction of CO2 to CO is a promising solution for the design of carbon-neutral, sustainable processes. Achieving a highly selective single reduction product is still challenging because of the energetically favorable competing hydrogen evolution reaction. We report the fabrication of N-doped sponge-like porous graphitic carbon structures embedded with Fe nanoparticles (Fe@NPC) via the pre-modification of a metal-organic framework (IRMOF-3(Zn)) with carboxyferrocene, followed by pyrolysis. The as-prepared Fe@NPC exhibited a 96.4% CO Faradaic efficiency at -0.5 VRHE and good stability. The exceptional CO2 reduction performance is attributed to the unique structure of the composite catalyst, which provides abundant hierarchical pores that increase CO2 adsorption and mass transfer, and active Fe sites that synergistically accelerate the kinetics of CO generation. The in situ attenuated total reflectance-Fourier transform infrared analysis provided proof of the improved ability of Fe@NPC to accumulate the crucial intermediate *COOH compared with other pyrolyzed porous carbons. Fe@NPC was used in a Zn-CO2 battery that delivered a maximum power density of 3.0 mW cm-2, evidencing its potential for application in energy-converting devices.

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Enhancing the chemoselective hydrogenation of nitroarenes: Designing a novel surface-strained carbon-based Pt nanocatalyst Fengwei Zhang, Hefang Guo, Mengmeng Liu, Yang Zhao, Feng Hong, Jingjing Li, Zhengping Dong, Botao Qiao 2023, 48:  195-204.  DOI: 10.1016/S1872-2067(23)64424-9 Abstract ( 193 )   HTML ( 8 )   PDF (5734KB) ( 100 )   Supporting Information Supported Pt nanoparticles (NPs) are highly active catalysts for heterogeneous catalytic hydrogenation reactions; however, controlling their selectivity remains the biggest challenge toward their applicability. Herein, we propose the formation of a highly selective and stable, surface-strained Pt-based nanocatalyst via a facile and scalable thermal reduction treatment. Spherical-aberration-corrected transmission electron microscopy (SACTEM) and various spectral analytic techniques reveal a strong metal-support interaction between the Pt NPs and carbon nanotubes (CNTs) support during the annealing process. Thereafter, a fraction of carbon atoms is etched from the carbon-coated Pt NPs, inducing a compressive strain on the surface of the Pt NPs. Notably, the chemoselectivity of the surface-strained Pt/CNTs-800H catalyst (where 800 represents the heat-treatment temperature; H represents a hydrogen atmosphere) is almost completely different compared to that of its pristine counterpart. This catalyst is used for the hydrogenation reactions of a styrene and nitrobenzene mixture as well as 4-nitrostyrene. Interestingly, similar findings were observed with 5 wt% Pt/C and Pt/rGO catalysts, confirming that this treatment could be generalized. Hence, it has great potential in the design and synthesis of carbon-based catalytic materials.

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Computational insights on potential dependence of electrocatalytic synthesis of ammonia from nitrate Huijuan Jing, Jun Long, Huan Li, Xiaoyan Fu, Jianping Xiao 2023, 48:  205-213.  DOI: 10.1016/S1872-2067(23)64413-4 Abstract ( 898 )   HTML ( 37 )   PDF (4844KB) ( 570 )   Supporting Information Electrochemical nitrate reduction reaction (eNO3RR) has been considered as an alternative route for decentralized ammonia (NH3) synthesis. However, a major challenge is products selectivity at low overpotentials, namely, the competition between nitrite (HNO2) and ammonia. Herein, we employed a single-atom catalyst (FeN4) as model to study the competitive mechanism of NH3 and HNO2 by density functional theory calculations. It was found the optimal paths for ammonia and nitrite productions share a key intermediate (NO2*), whose adsorption structures and preference in the following conversion determines the selectivity. We have incorporated potential-dependent barriers and microkinetic modeling to understand the Faradaic efficiency at different potentials. Our results are in good agreement with the experimental trend of Faradaic efficiencies of NH3 and HNO2, which can be rationalized well by the charge transfer coefficient (β) for NO2* protonation to cisHNO2* with respect to that to HNO2. A low selectivity of ammonia production at small overpotentials can be ascribed to a kinetic issue. The electron localization function and crystal orbital Hamilton population were analyzed on the initial and transition states for NO2* protonation to cisHNO2* and HNO2. The computational mechanistic insights can help to design new catalyst for eNO3RR highly active and selective to NH3.

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Phosphine-catalyzed photo-induced alkoxycarbonylation of alkyl iodides with phenols and 1,4-dioxane through charge-transfer complex Xing-Wei Gu, Youcan Zhang, Fengqian Zhao, Han-Jun Ai, Xiao-Feng Wu 2023, 48:  214-223.  DOI: 10.1016/S1872-2067(23)64398-0 Abstract ( 154 )   HTML ( 5 )   PDF (1156KB) ( 241 )   Supporting Information The combining of charge-transfer complex and light irradiation offers a promising solution for the requests of sustainable chemistry. Herein, we developed a phosphine-catalyzed visible light-induced alkoxycarbonylation of alkyl iodides with phenols and ethers. Based on the electron donor-acceptor photoactivation strategy, the reaction can be realized at atmospheric pressure of CO under transition metal-free conditions. This promising approach demonstrates high functional group tolerance and excellent chemoselectivity. Additionally, five-component perfluoroalkylative carbonylation for the synthesis of β-perfluoroalkyl acyloxy esters from unactivated olefins and perfluoroalkyl iodides can be realized as well. Moreover, due to the excellent performance of the gram-scale reaction and 13CO results, it provides potential opportunities for large-scale production and other applications.

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Defect engineering of Fe-N-C single-atom catalysts for oxygen reduction reaction Run Jiang, Zelong Qiao, Haoxiang Xu, Dapeng Cao 2023, 48:  224-234.  DOI: 10.1016/S1872-2067(23)64419-5 Abstract ( 442 )   HTML ( 30 )   PDF (13028KB) ( 552 )   Supporting Information Fe-N-C single-atom catalysts (SACs) have been widely considered as a promising candidate for oxygen reduction reaction (ORR), and its intrinsic activity is closely related to electronic and geometric structure of graphene supports. The carbon defect is widely existed in graphene, of which the intrinsic effect on ORR activity of Fe-N-C is still unclear. Here, we investigate ORR activity of 43 models representing Fe-N-C SACs accompanying with defects, including 555777, 5775 and 585-defects in three shell distances around FeN4 site. Both pre-adsorption of hydroxide radical during ORR and the distance between Fe SAC and defect are demonstrated to affect the orbital hybridizations between Fe SAC and *OH intermediate, including Fe(dxz)-O(px), Fe(dyz)-O(py) and Fe(dz2)-O(pz+s) orbitals, which can accordingly regulate ORR activity of defective Fe-N-C materials. Importantly, we establish a geometrical structure descriptor to quantitatively predict the ORR activity of defective Fe-N-C catalysts without any requirements of performing DFT calculations. With the assistance of the structure descriptor, we find that the 585 and 5775-defects of the large ring adjacent to the FeN4 pentagonal in fourth shell significantly boost the ORR performance of Fe-N-C. This work reveals the ORR activity origin of defective Fe-N-C materials, which provides intuitive guidance to boost the ORR performance of Fe-N-C materials by defect engineering, and may be extended to other types of defects and other single-atom catalysts.

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Activation of partial metal sites in high-entropy oxides for enhancing thermal and electrochemical catalysis Jinxing Mi, Xiaoping Chen, Yajun Ding, Liangzhu Zhang, Jun Ma, Hui Kang, Xianhong Wu, Yuefeng Liu, Jianjun Chen, Zhong-Shuai Wu 2023, 48:  235-246.  DOI: 10.1016/S1872-2067(23)64409-2 Abstract ( 384 )   HTML ( 11 )   PDF (6739KB) ( 361 )   Supporting Information High-entropy oxides (HEOs) have been tentatively and prospectively applied for chemical catalysis and energy storage. However, further enhancing their performance is difficult owing to the difficulty in precisely regulating the physical-chemical properties. In this work, a general in-situ modulation strategy of solid-phase combustion involving thiourea addition and alkali liquor treatment is developed to activate metal sites and lattice oxygen species of CuCoNiZnAl HEOs. Consequently, compared with pristine HEOs, the activated HEOs not only display higher CO2 hydrogenation and CO oxidation activities but also significantly enhanced electrocatalytic performance (discharge/charge capacities of 12049/9901 mAh/g) with excellent cycle stability (2500 h) for Li-O2 batteries. The superior performance of the activated HEOs is attributed to its facile electron transferability. This simple and effective strategy could be easily applied on a large scale, guiding the development of highly active heterogeneous HEO catalysts for various functional applications.

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In-situ adaptive evolution of rhodium oxide clusters into single atoms via mobile rhodium-adsorbate intermediates Zhengtian Pu, Haibin Yin, Xinlong Ma, Jin Zhao, Jie Zeng 2023, 48:  247-257.  DOI: 10.1016/S1872-2067(23)64426-2 Abstract ( 265 )   HTML ( 6 )   PDF (1390KB) ( 204 )   Supporting Information It is a common phenomenon for supported metal catalysts to undergo thermally-induced or adsorbate-induced reconstruction. Great efforts have been devoted to making these reconstruction adaptive to the reaction environment instead of deactivation. Herein, we reported the evolution of initially inactive RhOx clusters on Al2O3 into the formation of catalytically active oxygen vacancies and Rh single atoms via mobile Rh-CO intermediates during hydroformylation of propene. The activated catalyst exhibited a high specific activity of 3.0 × 104 mol molRh-1 h-1 towards hydroformylation reaction. Mechanistic studies revealed the evolution paths. Specially, RhOx clusters were reduced by CO to form oxygen vacancy where the surrounding unsaturated Rh atoms enabled the chemisorption of CO*. Rh atoms that were ejected from RhOx clusters diffused on Al2O3 supports to generate Rh single atom via the formation of carbonyl or geminal dicarbonyl species. Meanwhile, the Rh atoms on clusters were also leached to the solution by the adsorbed CO molecules, followed by partial re-adsorption on the support. This work not only offers an efficient catalyst for propene hydroformylation, but also advances the understandings of dynamic evolution of catalysts.

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Magnetic core-shell composites accessed by coordination assembly boost catalytic CO2 valorization Jinpeng Li, Jie Chen, Qingshu Zheng, Bo Tu, Tao Tu 2023, 48:  258-266.  DOI: 10.1016/S1872-2067(23)64400-6 Abstract ( 109 )   HTML ( 6 )   PDF (6453KB) ( 151 )   Supporting Information Magnetic core-shell composites are readily accessed by encapsulating Fe3O4 nanoparticles with NHC-M (M = Ir, Pd) coordination assemblies, which function as solid molecular catalysts and exhibit enhanced catalytic activity compared to the corresponding bis-NHC-Ir molecules in both hydrogenation and dehydrogenation reactions related to CO2. A record turnover number (TON: 1.69 × 106) was achieved in the hydrogenation of CO2 to formic acid. In addition, robust solid catalysts can be magnetically recovered and reused for more than 11 runs without obvious loss in activity and selectivity for the dehydrogenation of ammonium formate, even at 10-6 mmol level catalyst loadings.

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LSPR-enhanced carbon-coated In2O3/W18O49 S-scheme heterojunction for efficient CO2 photoreduction Houwei He, Zhongliao Wang, Kai Dai, Suwen Li, Jinfeng Zhang 2023, 48:  267-278.  DOI: 10.1016/S1872-2067(23)64420-1 Abstract ( 318 )   HTML ( 14 )   PDF (5413KB) ( 268 )   The special defect structure and localized surface plasmon resonance (LSPR) effect offer W18O49 extraordinary potential and research value in photocatalysis. The LSPR effect optimizes the design of W18O49-sensitized photocatalytic composites and broadens the light-response range of W18O49. However, the high-energy “hot electrons” generated by W18O49 under the LSPR effect exhibit an extremely short lifetime and cannot be fully utilized. Therefore, the high electron conductivity of carbon can be used to increase the rate of hot-electron transfer, thereby extending the lifetime of hot electrons. In this study, a heterojunction photocatalyst was formed by growing a high-absorbance one-dimensional nanowire W18O49 on the surface of carbon-coated porous In2O3 nanorods (C-In2O3) derived from In-MOF. The C-In2O3/W18O49 composites exhibited optical responses in both the visible and near-infrared regions. The carbon coatings acted as transport channels to accelerate the transfer of carriers and hot electrons, and the activity of photocatalytic CO2 reduction (PCR) was significantly enhanced. The 40%C-In2O3/W18O49 composites had the highest CO yield in the photocatalytic reactions, which was 2.99 and 2.84 times greater than that of pure C-In2O3 and W18O49, respectively. The internal electronic transfer in the S-scheme heterojunction and LSPR-induced hot electrons injected into C-In2O3 achieved dual-path electron transfer for PCR.

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Nanoscale lamination effect by nitrogen-deficient polymeric carbon nitride growth on polyhedral SrTiO3 for photocatalytic overall water splitting: Synergy mechanism of internal electrical field modulation Zhidong Wei, Jiawei Yan, Weiqi Guo, Wenfeng Shangguan 2023, 48:  279-289.  DOI: 10.1016/S1872-2067(23)64414-6 Abstract ( 229 )   HTML ( 14 )   PDF (11657KB) ( 362 )   Supporting Information The light penetration effect will weaken the driving force of charge separation from phase to surface by the built-in electric field of nanoscale photocatalysts, like low-dimensional materials. Therefore, in this study, a novel nanoscale lamination catalyst design method was proposed using a polymeric carbon nitride (PCN)-nano polyhedral SrTiO3 core-shell structure catalyst (PCN-SrTiO3). The results showed that the nanoscale lamination effect could be generated by the formation of the N-Sr bond, which could regulate the built-in electric field of the PCN simultaneously. Moreover, detailed characterization indicated that the N-Sr bond, which facilitates the generation of N vacancies in PCN, could act as a novel channel for charge transfer. Both surface and interior core N-deficient PCN have been discovered, resulting in more positive and negative VB positions, respectively. Synchronously, the light absorption ability of the PCN-SrTiO3 samples increased. Consequently, the enhanced photocatalytic overall water splitting could be ascribed to the synergism of the built-in electric field regulation caused by the N-Sr formation-induced nanoscale lamination effect, which was favorable for energy flow adaption on the spatiotemporal scale.