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Chinese Journal of Catalysis
2021, Vol. 42, No. 10
Online: 18 October 2021

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Cover: Prof. Ge and coworkers in their article on pages 1625–1633 describe the de novo approach to synthesize enzyme-metal hybrid catalysts which are promising to address challenges of biocatalysis. The structure-function relationship is discussed to reveal the principles of designing hybrid enzyme catalysts. They hope that this account will promote further efforts toward fundamental research and wide applications of enzyme hybrid catalysts for expanding biocatalysis.

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Hybrid enzyme catalysts synthesized by a de novo approach for expanding biocatalysis Yufei Cao, Jun Ge 2021, 42 (10):  1625-1633.  DOI: 10.1016/S1872-2067(21)63798-1 Abstract ( 493 )   HTML ( 343 )   PDF (3557KB) ( 643 )   The two major challenges in industrial enzymatic catalysis are the limited number of chemical reaction types that are catalyzed by enzymes and the instability of enzymes under harsh conditions in industrial catalysis. Expanding enzyme catalysis to a larger substrate scope and greater variety of chemical reactions and tuning the microenvironment surrounding enzyme molecules to achieve high enzyme performance are urgently needed. In this account, we focus on our efforts using the de novo approach to synthesis hybrid enzyme catalysts that can address these two challenges and the structure-function relationship is discussed to reveal the principles of designing hybrid enzyme catalysts. We hope that this account will promote further efforts toward fundamental research and wide applications of designed enzyme hybrid catalysts for expanding biocatalysis.

Communications

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Iron phthalocyanine-catalyzed radical phosphinoylazidation of alkenes: A facile synthesis of β-azido-phosphine oxide with a fast azido transfer step Xiaoxu Ma, Mong-Feng Chiou, Liang Ge, Xiaoyan Li, Yajun Li, Li Wu, Hongli Bao 2021, 42 (10):  1634-1640.  DOI: 10.1016/S1872-2067(21)63847-0 Abstract ( 306 )   HTML ( 25 )   PDF (2396KB) ( 409 )   Phosphinoylazidation of alkenes is a direct method to build nitrogen- and phosphorus-containing compounds from feed-stock chemicals. Notwithstanding the advances in other phosphinyl radical related difunctionalization of alkenes, catalytic phosphinoylazidation of alkenes has not yet been reported. Here, we describe the first iron-catalyzed intermolecular phosphinoylazidation of styrenes and unactivated alkenes. The method is practically useful and requires a relatively low loading of catalyst. Mechanistic studies confirmed the radical nature of the reaction and disclosed the unusually low activation energy 4.8 kcal/mol of radical azido group transfer from the azidyl iron(III) phthalocyanine species (PcFeIIIN3) to a benzylic radical. This work may help to clarify the mechanism of iron-catalyzed azidation, inspire other mechanism studies and spur further synthetic applications.

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Photocatalytic-controlled olefin isomerization over WO3-x using low-energy photons up to 625 nm Pengqi Zhu, Yunwei Wang, Xichen Sun, Jin Zhang, Eric R. Waclawik, Zhanfeng Zheng 2021, 42 (10):  1641-1647.  DOI: 10.1016/S1872-2067(21)63815-9 Abstract ( 204 )   HTML ( 15 )   PDF (2926KB) ( 288 )   Supporting Information WO3-x (W-1) was used to achieve controllable photoisomerization of linear olefins without substituents under 625 nm light irradiation. Thermodynamic and kinetic isomers were obtained by regulating the carbon chain length of the olefins. Terminal olefins were converted into isomerized products, and the internal olefin mixtures present in petroleum derivatives were transformed into valuable pure olefin products. Oxygen vacancies (OVs) in W-1 altered the electronic structure of W-1 to improve its light-harvesting ability, which accounted for the high activity of olefin isomerization under light irradiation up to 625 nm. Additionally, OVs on the W-1 surface generated unsaturated W5+ sites that coordinated with olefins for the efficient adsorption and activation of olefins. Mechanistic studies reveal that the in situ formation of surface π-complexes and π-allylic W intermediates originating from the coordination of coordinated unsaturated W5+ sites and olefins ensure high photocatalytic activity and selectivity of W-1 for the photocatalytic isomerization of olefins via a radical mechanism.

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In-situ preparation of TiO2/N-doped graphene hollow sphere photocatalyst with enhanced photocatalytic CO2 reduction performance Libo Wang, Bicheng Zhu, Bei Cheng, Jianjun Zhang, Liuyang Zhang, Jiaguo Yu 2021, 42 (10):  1648-1658.  DOI: 10.1016/S1872-2067(21)63805-6 Abstract ( 305 )   HTML ( 25 )   PDF (3597KB) ( 385 )   Supporting Information Photocatalytic CO2 conversion efficiency is hampered by the rapid recombination of photogenerated charge carriers. It is effective to suppress the recombination by constructing cocatalysts on photocatalysts with high-quality interfacial contact. Herein, we develop a novel strategy to in-situ grow ultrathin N-doped graphene (NG) layer on TiO2 hollow spheres (HS) with large area and intimate interfacial contact via a chemical vapor deposition (CVD). The optimized TiO2/NG HS nanocomposite achieves total CO2 conversion rates (the sum yield of CO, CH3OH and CH4) of 18.11 μmol g-1 h-1, which is about 4.6 times higher than blank TiO2 HS. Experimental results demonstrate that intimate interfacial contact and abundant pyridinic N sites can effectively facilitate photogenerated charge carrier separation and transport, realizing enhanced photocatalytic CO2 reduction performance. In addition, this work provides an effective strategy for in-situ construction of graphene-based photocatalysts for highly efficient photocatalytic CO2 conversion.

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Catalytic activity of V2CO2 MXene supported transition metal single atoms for oxygen reduction and hydrogen oxidation reactions: A density functional theory calculation study Zhongjing Deng, Xingqun Zheng, Mingming Deng, Li Li, Li Jing, Zidong Wei 2021, 42 (10):  1659-1666.  DOI: 10.1016/S1872-2067(21)63823-8 Abstract ( 326 )   HTML ( 17 )   PDF (1912KB) ( 396 )   Supporting Information Two-dimensional (2D) MXene and single-atom (SA) catalysts are two frontier research fields in catalysis. 2D materials with unique geometric and electronic structures can modulate the catalytic performance of supported SAs, which, in turn, affect the intrinsic activity of 2D materials. Density functional theory calculations were used to systematically explore the potential of O-terminated V2C MXene (V2CO2)-supported transition metal (TM) SAs, including a series of 3d, 4d, and 5d metals, as oxygen reduction reaction (ORR) and hydrogen oxidation reaction (HOR) catalysts. The combination of TM SAs and V2CO2 changes their electronic structure and enriches the active sites, and consequently regulates the intermediate adsorption energy and catalytic activity for ORR and HOR. Among the investigated TM-V2CO2 models, Sc-, Mn-, Rh-, and Pt-V2CO2 showed high ORR activity, while Sc-, Ti-, V-, Cr-, and Mn-V2CO2 exhibited high HOR activity. Specifically, Mn- and Sc-V2CO2 are expected to serve as highly efficient and cost-effective bifunctional catalysts for fuel cells because of their high catalytic activity and stability. This work provides theoretical guidance for the rational design of efficient ORR and HOR bifunctional catalysts.

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“Environmental phosphorylation” boosting photocatalytic CO2 reduction over polymeric carbon nitride grown on carbon paper at air-liquid-solid joint interfaces Qinghe Zhang, Yang Xia, Shaowen Cao 2021, 42 (10):  1667-1676.  DOI: 10.1016/S1872-2067(21)63824-X Abstract ( 287 )   HTML ( 13 )   PDF (2227KB) ( 373 )   Supporting Information The limited CO2 content in aqueous solution and low adsorption amount of CO2 on catalyst surface lead to poor photocatalytic CO2 reduction activity and selectivity. Herein, the design and fabrication of a novel photocatalytic architecture is reported, accomplished via chemical vapor deposition of polymeric carbon nitride on carbon paper. The as-obtained samples with a hydrophobic surface exhibit excellent CO2 transport and adsorption ability, as well as the building of triphase air-liquid-solid (CO2-H2O-catalyst) joint interfaces, eventually resulting in the inhibition of H2 evolution and great promotion of CO2 reduction with a selectivity of 78.6%. The addition of phosphate to reaction environment makes further improvement of CO2 photoreduction into carbon fuels with a selectivity of 93.8% and an apparent quantum yield of 0.4%. This work provides new insight for constructing efficient photocatalytic architecture of CO2 photoreduction in aqueous solution and demonstrates that phosphate could play a key role in this process.

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Mechanism investigation of PtPd decorated Zn0.5Cd0.5S nanorods with efficient photocatalytic hydrogen production combining with kinetics and thermodynamics Linhe Zhang, Fudong Zhang, Huaqing Xue, Jianfeng Gao, Yong Peng, Weiyu Song, Lei Ge 2021, 42 (10):  1677-1688.  DOI: 10.1016/S1872-2067(21)63791-9 Abstract ( 234 )   HTML ( 10 )   PDF (4097KB) ( 422 )   Different components of PtPd bimetallic cocatalysts modified Zn0.5Cd0.5S nanorods have already been designed and prepared in this study. The obtained hybrid photocatalysts were tested and characterized by XPS, ICP-OES and UV-Vis spectra, TEM and EDX tools. Such characterizations can prove the formation of PtPd bimetallic alloy particles in hybrid catalysts. Under visible light illumination, an outstanding hydrogen producing rate of 9.689 mmol·g-1·h-1 and a high AQY efficiency up to 10.43% at 420 nm are achieved in this work. In addition, thermodynamics (DFT calculations) and kinetics (Photoluminescence emission, photocurrent responses, electrochemical impedance spectroscopy and surface photovoltage spectra) investigations illustrate that PtPd bimetallic alloy has similar catalytic thermodynamic properties to Pt, which can greatly boost the charge separation and speed up the charge transfer, and decrease the activation energy of H2 generation. Notably, the calculation data suggests that Pt is thermodynamically favorable, while PtPd alloy is kinetically beneficial to H2 production, which can be ascribed to the higher activity of PtPd/Zn0.5Cd0.5S than Pt/Zn0.5Cd0.5S. This work can propose a fresh perspective for preparing high efficiency hybrid photocatalysts.

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Methane combustion over palladium catalyst within the confined space of MFI zeolite Mingyang Gao, Zhongmiao Gong, Xuefei Weng, Weixiang Shang, Yuchao Chai, Weili Dai, Guangjun Wu, Naijia Guan, Landong Li 2021, 42 (10):  1689-1699.  DOI: 10.1016/S1872-2067(20)63775-5 Abstract ( 402 )   HTML ( 15 )   PDF (6515KB) ( 537 )   Supporting Information Isolated cationic Pd species encapsulated in MFI zeolite, i.e., Pd@MFI, have been successfully prepared via in situ hydrothermal route followed by oxidative treatment. The as-prepared Pd@MFI samples are investigated as promising catalysts in the reaction of methane combustion. Typically, Pd@H-ZSM-5 shows remarkable activity in methane catalytic combustion with a low apparent activation energy value of 70.7 kJ/mol as well as good catalytic stability even in excess water vapor. Detailed characterization results demonstrate the strong interaction between Pd sites and zeolite framework in Pd@ZSM-5 and the efficient stabilization of isolated Pd sites by zeolite thereof. Spectroscopy analyses reveal that the presence of Brønsted acid sites is beneficial to methane adsorption and its subsequent activation on adjacent Pd sites, constructing cooperation between Brønsted acid sites and Pd sites within the confined space of MFI zeolite toward high-efficiency methane catalytic combustion. The reaction mechanism of methane combustion catalyzed by Pd@H-ZSM-5 model catalyst is finally discussed.

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Mixed hetero-/homogeneous TiO2/N-hydroxyimide photocatalysis in visible-light-induced controllable benzylic oxidation by molecular oxygen Igor B. Krylov, Elena R. Lopat’eva, Irina R. Subbotina, Gennady I. Nikishin, Bing Yu, Alexander O. Terent’ev 2021, 42 (10):  1700-1711.  DOI: 10.1016/S1872-2067(21)63831-7 Abstract ( 182 )   HTML ( 9 )   PDF (2140KB) ( 421 )   Homogeneous and heterogeneous types of catalysis are frequently considered as separate disciplines or even opposed to each other. In the present work, a new type of mixed hetero-/homogeneous catalysis was demonstrated for the case of selective alkylarene oxidation by molecular oxygen. The proposed catalytic system consists of two widely available components: N-hydroxyphthalimide (NHPI, a homogeneous organocatalyst for free-radical chain reactions) and nanosized TiO2 (heterogeneous UV-active photoredox catalyst). The interaction of NHPI with TiO2 allows for a shift from UV to visible light photoredox activity and generation of phthalimide-N-oxyl (PINO) radicals that diffuse into the solution where NHPI/PINO-catalyzed free-radical chain reaction can proceed without the additional light input providing a fundamental increase in energy efficiency. The NHPI/TiO2 ratio controls the selectivity of oxidation affording preferential formation of hydroperoxide or ketone from alkylarene.

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Ru surface density effect on ammonia synthesis activity and hydrogen poisoning of ceria-supported Ru catalysts Bingyu Lin, Yuyuan Wu, Biyun Fang, Chunyan Li, Jun Ni, Xiuyun Wang, Jianxin Lin, Lilong Jiang 2021, 42 (10):  1712-1723.  DOI: 10.1016/S1872-2067(20)63787-1 Abstract ( 572 )   HTML ( 25 )   PDF (1683KB) ( 535 )   Supporting Information Evaluating the effect of metal surface density on catalytic performance is critical for designing high-activity metal-based catalysts. In this study, a series of ceria (CeO2)-supported Ru catalysts (Ru/CeO2) were prepared to analyze the effect of Ru surface density on the catalytic performance of Ru/CeO2 for ammonia synthesis. For the Ru/CeO2 catalysts with Ru surface densities lower than 0.68 Ru nm-2, the Ru layers were in close contact with CeO2, and electrons were transferred directly from the CeO2 defect sites to the Ru species. In such cases, the adsorption of hydrogen species on the Ru sites in the vicinity of O atoms was high, leading to a high ammonia synthesis activity and strong hydrogen poisoning. In contrast, the preferential aggregation of Ru species into large particles on top of the Ru overlayer resulted in the coexistence of Ru clusters and particles, for catalysts with a Ru surface density higher than 1.4 Ru nm-2, for which Ru particles were isolated from the direct electronic influence of CeO2. Consequently, the Ru-CeO2 interactions were weak, and hydrogen poisoning can be significantly alleviated. Overall, electron transfer and hydrogen adsorption synergistically affected the synthesis of ammonia over Ru/CeO2 catalysts, and catalyst samples with a Ru surface density lower than 0.31 Ru nm-2 or exactly 2.1 Ru nm-2 exhibited high catalytic activity for ammonia synthesis.

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An unusual network of α-MnO2 nanowires with structure-induced hydrophilicity and conductivity for improved electrocatalysis Yingdong Chen, Shujiao Yang, Hongfei Liu, Wei Zhang, Rui Cao 2021, 42 (10):  1724-1731.  DOI: 10.1016/S1872-2067(21)63793-2 Abstract ( 347 )   HTML ( 17 )   PDF (2401KB) ( 354 )   Supporting Information Nanowires with anisotropic morphologies have been applied in various scientific and technological areas. It is also widely employed to fabricate nanowires into high-dimensional superstructures (arrays, networks etc.) to overcome the shortcomings of low-dimensional nanowires. However, typical strategies for constructing these superstructures are restricted to complicated and harsh synthetic conditions, not to mention unique 3D structures with advanced properties beyond common superstructures. Herein, we report an unusual network of α-MnO2 nanowires with structure-induced hydrophilicity and conductivity. In the network, the nanowires are interconnected from all directions by nodes, and the 3D network structure is formed from the endless connection of nodes in a node-by-node way. The unique network structure brings about high hydrophilicity and conductivity, both of which are positive factors for an efficient electrocatalyst. Accordingly, the α-MnO2 network was tested for electrocatalytic water oxidation and showed significantly enhanced activity compared with isolated α-MnO2 nanowires and 3D α-MnO2 microspheres. This study not only provides a synthetic route toward an advanced network structure but also a new idea for the design of materials for electrochemistry with both efficient mass diffusion and charge transfer.

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Self-supporting NiFe LDH-MoSx integrated electrode for highly efficient water splitting at the industrial electrolysis conditions Han Zhang, Guoqiang Shen, Xinying Liu, Bo Ning, Chengxiang Shi, Lun Pan, Xiangwen Zhang, Zhen-Feng Huang, Ji-Jun Zou 2021, 42 (10):  1732-1741.  DOI: 10.1016/S1872-2067(21)63796-8 Abstract ( 503 )   HTML ( 29 )   PDF (3346KB) ( 545 )   Supporting Information Developing effective and practical electrocatalyst under industrial electrolysis conditions is critical for renewable hydrogen production. Herein, we report the self-supporting NiFe LDH-MoSx integrated electrode for water oxidation under normal alkaline test condition (1 M KOH at 25 °C) and simulated industrial electrolysis conditions (5 M KOH at 65 °C). Such optimized electrode exhibits excellent oxygen evolution reaction (OER) performance with overpotential of 195 and 290 mV at current density of 100 and 400 mA·cm-2 under normal alkaline test condition. Notably, only overpotential of 156 and 201 mV were required to achieve the current density of 100 and 400 mA·cm-2under simulated industrial electrolysis conditions. No significant degradations were observed after long-term durability tests for both conditions. When using in two-electrode system, the operational voltages of 1.44 and 1.72 V were required to achieve a current density of 10 and 100 mA·cm-2 for the overall water splitting test (NiFe LDH-MoSx/INF || 20% Pt/C). Additionally, the operational voltage of employing NiFe LDH-MoSx/INF as both cathode and anode merely require 1.52 V at 50 mA·cm-2 at simulated industrial electrolysis conditions. Notably, a membrane electrode assembly (MEA) for anion exchange membrane water electrolysis (AEMWEs) using NiFe LDH-MoSx/INF as an anode catalyst exhibited an energy conversion efficiency of 71.8% at current density of 400 mA·cm-2 in 1 M KOH at 60 °C. Further experimental results reveal that sulfurized substrate not only improved the conductivity of NiFe LDH, but also regulated its electronic configurations and atomic composition, leading to the excellent activity. The easy-obtained and cost-effective integrated electrodes are expected to meet the large-scale application of industrial water electrolysis.

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The effects of TiO2 crystal-plane-dependent Ir-TiOx interactions on the selective hydrogenation of crotonaldehyde over Ir/TiO2 catalysts Aiping Jia, Yunshang Zhang, Tongyang Song, Yiming Hu, Wanbin Zheng, Mengfei Luo, Jiqing Lu, Weixin Huang 2021, 42 (10):  1742-1754.  DOI: 10.1016/S1872-2067(21)63810-X Abstract ( 202 )   HTML ( 9 )   PDF (3101KB) ( 339 )   Supporting Information Three supported Ir/TiO2 catalysts, containing anatase TiO2 nanocrystals with predominantly exposed {101}, {100}, and {001} planes, were subjected to various pre-treatments (H2 reduction at different temperatures and O2 re-oxidation) and then tested in the vapor phase selective hydrogenation of crotonaldehyde. The pre-treatments significantly altered the Ir-TiOx interactions, including the morphologies and electronic properties of the Ir species and their surface acidity. These interactions were also closely related to the crystal planes of TiO2, which further supported the observed reaction behaviors of the various Ir/TiO2 catalysts. The best performance was obtained using the Ir/TiO2-{101} catalyst pre-reduced at 300 °C, owing to its higher Ir0 surface concentration and moderate surface acidity compared to the other catalysts. Moreover, these findings indicated the synergistic role of the Ir-TiOx interface in the reaction, as the interfacial sites were responsible for the adsorption/activation of H2 and the C=O bond in the crotonaldehyde molecule. However, pre-reduction at 400 °C resulted in partial encapsulation of the Ir particles by TiOx via strong metal-support interactions, which is unfavorable for the catalytic reaction owing to the loss of Ir-TiOx interfacial sites.

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La-doped TiO2 nanorods toward boosted electrocatalytic N2-to-NH3 conversion at ambient conditions Li Li, Haijun Chen, Lei Li, Baihai Li, Qianbao Wu, Chunhua Cui, Biao Deng, Yonglan Luo, Qian Liu, Tingshuai Li, Fang Zhang, Abdullah M. Asiri, Zhe-Sheng Feng, Yan Wang, Xuping Sun 2021, 42 (10):  1755-1762.  DOI: 10.1016/S1872-2067(21)63795-6 Abstract ( 218 )   HTML ( 8 )   PDF (1986KB) ( 360 )   Supporting Information Electrochemical N2 reduction provides a green and sustainable alternative to the Haber-Bosch technology for NH3 synthesis. However, the extreme inertness of N2 molecules is a formidable challenge, which requires the development of an active electrocatalyst to drive the N2 reduction reaction (NRR) for NH3 production at ambient conditions. Herein, we demonstrate the development of La-doped TiO2 nanorods as an efficient NRR electrocatalyst for ambient NH3 synthesis. The optimized La-TiO2 catalyst offers a large NH3 yield of 23.06 μg h-1 mgcat-1 and a high Faradaic efficiency of 14.54% at -0.70 V versus reversible hydrogen electrode in 0.1 M LiClO4, outperforming most La- and Ti-based catalysts reported before. Significantly, it also demonstrates high electrochemical stability and its activity decay is negligible after 48 h test. The mechanism is further revealed by density functional theory calculations.

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Tunable and stable localized surface plasmon resonance in SrMoO4 for enhanced visible light driven nitrogen reduction Qiang Li, Zhenhuan Zhao, Xiaoxia Bai, Xin Tong, Shuai Yue, Jingying Luo, Xin Yu, Zhenni Wang, Zheng Wang, Peipei Li, Yanping Liang, Zhiming Wang 2021, 42 (10):  1763-1771.  DOI: 10.1016/S1872-2067(21)63799-3 Abstract ( 389 )   HTML ( 22 )   PDF (2186KB) ( 437 )   Supporting Information Photocatalytic nitrogen reduction for the green synthesis of ammonia at ambient conditions has been slowed by the narrow light harvesting range, low activity and high charge recombination of photocatalysts. Plasmonic semiconducting nanomaterials are becoming the promising candidates for nitrogen photofixation because of the broad absorption spectrum, rich defects and hot carriers. In the present study, plasmonic SrMoO4 is developed by regulating the concentration of oxygen vacancies that are accompanied in the reduction process from Mo6+ to Mo5+. The stable and tunable localized surface plasmon resonance (LSPR) absorption in visible and near infrared light range makes the wide bandgap SrMoO4 utilize the solar energy more efficiently. Energetic electrons from both the intrinsic band excitation and the LSPR excitation enable the reduction of dinitrogen molecules thermodynamically in ultrapure water to ammonia. This work provides a unique clue to design efficient photocatalysts for nitrogen fixation.

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A highly active and stable organic-inorganic combined solid acid for the transesterification of glycerol under mild conditions Yuanyuan Jiang, Ruru Zhou, Huaiyuan Zhao, Boyong Ye, Yihua Long, Zhengbao Wang, Zhaoyin Hou 2021, 42 (10):  1772-1781.  DOI: 10.1016/S1872-2067(21)63811-1 Abstract ( 308 )   HTML ( 19 )   PDF (3039KB) ( 375 )   Supporting Information S olid acid catalyst plays a crucial role in the petroleum refinery industry and bio-refinery technology. In this work, p-phenolsulfonic acid (PSA) was successfully grafted onto the surface of KH560-modified zirconium phosphate (K-ZrP) in a facile routine. The structure and property of this organic-inorganic combined solid acid PSA/K-ZrP-x were characterized via XRD, FTIR, 13C solid-state NMR, TG, N2 adsorption-desorption, SEM, pyridine-adsorption FTIR and XPS technologies. The characterization results showed that KH560 can bond with ZrP and promote the grafting of PSA on the surface of K-ZrP via the condensation reaction between its epoxy ring and the phenolic hydroxyl group in PSA. Consequently, PSA/K-ZrP-2 exhibited excellent performance and stability in the transesterification between glycerol and methyl acetate among the tested H3PW12O40, Amberlyst-45, HBEA, HZSM-5, ZrP, AlCl3 and FeCl3 catalysts. The calculated conversion of glycerol reached 81.3% with a 97.9% selectivity for monoacetin (MAG) and diacetin (DAG) with a 2.2% dosage of [H+] at 100 °C for 4 h. The highest specific activity of PSA/K-ZrP-2 reached 24028.2 mg-glycerol/g-cat/h in a short reaction time (at 0.17 h), and it could be recycled five times without obvious deactivation.

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Electrospinning synthesis of porous boron-doped silica nanofibers for oxidative dehydrogenation of light alkanes Bing Yan, Wen-Duo Lu, Jian Sheng, Wen-Cui Li, Ding Ding, An-Hui Lu 2021, 42 (10):  1782-1789.  DOI: 10.1016/S1872-2067(21)63809-3 Abstract ( 162 )   HTML ( 4 )   PDF (4878KB) ( 307 )   Supporting Information The discovery of the high activity and selectivity of boron-based catalysts for oxidative dehydrogenation (ODH) of alkanes to olefins has attracted significant attention in the exploration of a new method for the synthesis of highly active and selective catalysts. Herein, we describe the synthesis of porous boron-doped silica nanofibers (PBSNs) 100-150 nm in diameter by electrospinning and the study of their catalytic performance. The electrospinning synthesis of the catalyst ensures the uniform dispersion and stability of the boron species on the open silica fiber framework. The one-dimensional nanofibers with open pore structures not only prevented diffusion limitation but also guaranteed high catalytic activity at high weight hourly space velocity (WHSV) in the ODH of alkanes. Compared to other supported boron oxide catalysts, PBSN catalysts showed higher olefin selectivity and stability. The presence of Si-OH groups in silica-supported boron catalysts may cause low propylene selectivity during the ODH of propane. When the ODH conversion of ethane reached 44.3%, the selectivity and productivity of ethylene were 84% and 44.2% gcat-1 s-1, respectively. In the case of propane ODH, the conversion, selectivity of olefins, and productivity of propylene are 19.2%, 90%, and 76.6 μmol gcat-1 s-1, respectively. No significant variations in the conversion and product selectivity occurred during 20 h of operation at a high WHSV of 84.6 h-1. Transient analysis and kinetic experiments indicated that the activation of O2 was influenced by alkanes during the ODH reaction.

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Doping [Ru(bpy)3]2+ into metal-organic framework to facilitate the separation and reuse of noble-metal photosensitizer during CO2 photoreduction Zhe Wu, Song Guo, Li-Hui Kong, Ai-Fang Geng, Yu-Jie Wang, Ping Wang, Shuang Yao, Kai-Kai Chen, Zhi-Ming Zhang 2021, 42 (10):  1790-1797.  DOI: 10.1016/S1872-2067(21)63820-2 Abstract ( 381 )   HTML ( 15 )   PDF (2242KB) ( 385 )   Supporting Information It is desirable to develop highly efficient and sustainable catalytic systems for CO2 photoreduction using efficient heterogeneous photosensitizers (PSs); however, this remains a great challenge. In this study, we doped [Ru(bpy)3]2+ into UiO-metal-organic frameworks (MOFs) to facilitate the separation and reuse of noble metal PS. By simply adjusting the loading amount, a series of heterogeneous photoactive MOFs, namely, UiO-Ru-1, UiO-Ru-2, and UiO-Ru-3, were constructed to act as heterogeneous PSs to drive the efficient CO2 photoreduction under visible-light irradiation. Remarkably, UiO-Ru-2 exhibited the best photosensitizing ability among the prepared MOFs in sensitizing the iron quarterpyridine catalyst (C-1), and the CO yield reached as high as 171 mmol/g with ca. 100% selectivity, which is a record value among all the MOF-based photocatalysts. This photoactive MOF can be recycled and reused three times without any obvious activity loss, signifying its good photochemical stability. Experimental investigations confirmed that the strong visible absorption, long-lived excited state, appropriate redox potential, good photocatalytic stability, and excellent collaboration with C-1 were attributable to the superior catalytic activity. This work highlights an avenue for constructing heterogeneous PSs with excellent recyclability using MOF as the platform for efficient CO2 reduction.

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Controlling atomic phosphorous-mounting surfaces of ultrafine W2C nanoislands monodispersed on the carbon frameworks for enhanced hydrogen evolution Xiangyong Zhang, Tianying Liu, Ting Guo, Xueying Han, Zongyun Mu, Qiang Chen, Jiangmin Jiang, Jing Yan, Jiaren Yuan, Dezhi Wang, Zhuangzhi Wu, Zongkui Kou 2021, 42 (10):  1798-1807.  DOI: 10.1016/S1872-2067(21)63808-1 Abstract ( 179 )   HTML ( 7 )   PDF (5990KB) ( 288 )   Supporting Information Controllably mounting foreign atoms on the surfaces of earth-abundant electrocatalysts strongly improve their surface electronic properties for optimizing the catalytic performance of surficial sites to an unusual level, and provides a good platform to gain deep insights into catalytic reactions. The present work describes, employing ultrafine W2C nanoislands (average size: 2.3 nm) monodispersed on the N, P dual-doped carbon frameworks as a model system, how to regulate the atomic phosphorous-mounting effect on the surfaces of W2C to derive an active and stable P-mounting W2C (WCP) catalyst for both acidic and alkaline hydrogen evolution reaction (HER). Since in situ phosphorus substitution into carbon sites of preformed W2C nanoislands gradually proceeds from surfaces to solids, so that using a proper amount of phosphorus sources can readily control the surface mounting level to avoid the mass P-doping into the bulk. By this way, the activity per active site of WCP catalyst with robust stability can be optimized to 0.07 and 0.56 H2 s-1 at -200 mV overpotential in acid and base, respectively, which reach up to the several-fold of pure-phase W2C (0.01 and 0.05 H2 s-1). Theoretical investigations suggest that compared with solid P doping, the P mounting on W2C surface can more remarkably enhance its metallicity and decrease the hydrogen release barrier. This finding disclosed a key correlation between surface foreign atom-mounting and catalytic activity, and suggested a logical extension to other earth-abundant catalysts for various catalytic reactions.

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Trifunctional strategy for the design and synthesis of a Ni-CeO2@SiO2 catalyst with remarkable low-temperature sintering and coking resistance for methane dry reforming Sixue Lin, Jing Wang, Yangyang Mi, Senyou Yang, Zheng Wang, Wenming Liu, Daishe Wu, Honggen Peng 2021, 42 (10):  1808-1820.  DOI: 10.1016/S1872-2067(21)63789-0 Abstract ( 573 )   HTML ( 23 )   PDF (12378KB) ( 496 )   Supporting Information In this study, a trifunctional strategy was developed to prepare a confined Ni-based catalyst (Ni-CeO2@SiO2) for dry reforming of methane (DRM) of two main greenhouse gases—CO2 and CH4. The Ni-CeO2@SiO2 catalyst was fabricated by utilizing the confinement effect of the SiO2 shell and the synergistic interaction between Ni-Ce and the decoking effect of CeO2. The catalysts were systematically characterized via X-ray diffraction, N2 adsorption/desorption, transmission electron microscopy, energy dispersive X-ray spectroscopy, hydrogen temperature reduction and desorption set by program, oxygen temperature program desorption, Raman spectroscopy, thermogravimetric analysis, and in situ diffuse reflectance infrared Fourier transform spectroscopy measurements to reveal their physicochemical properties and reaction mechanism. The Ni-CeO2@SiO2 catalyst exhibited higher activity and stability than the catalyst synthesized via the traditional impregnation method. In addition, no carbon deposition was detected over Ni-CeO2@SiO2 after a 100 h durability test at 800 °C, and the average particle size of Ni nanoparticles (NPs) in the catalyst increased from 5.01 to 5.77 nm. Remarkably, Ni-CeO2@SiO2 also exhibited superior low-temperature stability; no coke deposition was observed when the catalyst was reacted at 600 °C for 20 h. The high coking and sintering resistance of this confined Ni-based DRM catalyst can be attributed to its trifunctional effect. The trifunctional strategy developed in this study could be used as a guideline to design other high-performance catalysts for CO2 and CH4 dry forming and accelerate their industrialization.

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One-pot synthesis of mesosilica/nano covalent organic polymer composites and their synergistic effect in photocatalysis Chengbin Li, He Li, Chunzhi Li, Xiaomin Ren, Qihua Yang 2021, 42 (10):  1821-1830.  DOI: 10.1016/S1872-2067(21)63812-3 Abstract ( 331 )   HTML ( 13 )   PDF (5507KB) ( 371 )   Supporting Information Organic-inorganic hybrid materials provide a desirable platform for the development of novel functional materials. Here, we report the one-pot synthesis of mesoporous hybrid nanospheres by the in-situ sol-gel condensation of tetraethoxysilane around surfactant micelle-confined nano covalent organic polymer (nanoCOP) colloids. The hybrid nanospheres containing nanoCOPs uniformly distributed in the mesosilica network, inherited the visible light responsive properties of the nanoCOPs. The turnover frequency of the hybrid nanospheres is almost 12 times that of its corresponding bulk COP counterpart for the photocatalytic reductive dehalogenation of α-bromoacetophenone, which is attributed to activation of the Hantzsch ester reductant by the hydroxyl group. The existence of a volcano relationship between the activity and nanoCOP/mesosilica ratio confirmed the synergistic effect between nanoCOP and mesosilica. Our preliminary results suggest that hybridization of semiconductors and reactant-activating materials is an efficient strategy for enhancing the activity of a catalyst for photocatalysis.