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Chinese Journal of Catalysis
2021, Vol. 42, No. 2
Online: 18 February 2021

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Cover: Dr. Zhang and Prof. Fan in their article on pages 251–258 reported a facile grinding strategy to successfully produce a series of PdAg alloy nanoparticles with a small size and good distribution on the carbon matrix. Those samples as the electrocatalysts could exhibit excellent activities and stabilities for the alkaline hydrogen oxidation and evolution reactions.

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Communication

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Evolution of catalytic activity driven by structural fusion of icosahedral gold cluster cores Dan Yang, Yan Zhu 2021, 42 (2):  245-250.  DOI: 10.1016/S1872-2067(20)63659-2 Abstract ( 179 )   HTML ( 325 )   PDF (2547KB) ( 355 )   Supporting Information Atomically precise gold cluster catalysts have emerged as a new frontier in catalysis science, owing to their unexpected catalytic properties. In this work, we explore the evolution of the catalytic activity of clusters formed by the structural fusion of icosahedral Au13 units, namely Au25(SR)18, Au38(SR)24, and Au25(PPh3)10(SC2H4Ph)5Cl2, in the oxidation of pyrrolidine to γ-butyrolactam. We demonstrate that the structural fusion of icosahedral Au13 units, forming vertex-fused (vf), face-fused (ff), and body-fused (bf) clusters, can induce a decrease in the catalytic activity in the following order: Aubf > Auff > Auvf. The structural fusion of icosahedral Au13 units in the clusters does not distinguish the adsorption modes of pyrrolidine over the three clusters from each other, but modulates the chemical adsorption capacity and electronic properties of the three clusters, which is likely to be the key reason for the observed changes in catalytic reactivity. Our results are expected to be extendable to study and design atomically defined catalysts with elaborate structural patterns, in order to produce desired products.

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Sustainable solid-state synthesis of uniformly distributed PdAg alloy nanoparticles for electrocatalytic hydrogen oxidation and evolution Caili Xu, Qian Chen, Rong Ding, Shengtian Huang, Yun Zhang, Guangyin Fan 2021, 42 (2):  251-258.  DOI: 10.1016/S1872-2067(20)63650-6 Abstract ( 241 )   HTML ( 16 )   PDF (2330KB) ( 424 )   Supporting Information New sustainable syntheses based on solid-state strategies have sparked enormous attention and provided novel routes for the synthesis of supported metallic alloy nanocatalysts (SMACs). Despite considerable recent progress in this field, most of the developed methods suffer from either complex operations or poorly controlled morphology, which seriously limits their practical applications. Here, we have developed a sustainable strategy for the synthesis of PdAg alloy nanoparticles (NPs) with an ultrafine size and good dispersion on various carbon matrices by directly grinding the precursors in an agate mortar at room temperature. Interestingly, no solvents or organic reagents are used in the synthesis procedure. This simple and green synthesis procedure provides alloy NPs with clean surfaces and thus an abundance of accessible active sites. Based on the combination of this property and the synergistic and alloy effects between Pd and Ag atoms, which endow the NPs with high intrinsic activity, the PdAg/C samples exhibit excellent activities as electrocatalysts for both the hydrogen oxidation and evolution reactions (HOR and HER) in a basic medium. Pd9Ag1/C showed the highest activity in the HOR with the largest j0,m value of 26.5 A g Pd-1 and j0,s value of 0.033 mA cmPd -2, as well as in the HER, with the lowest overpotential of 68 mV at 10 mA cm-2. As this synthetic method can be easily adapted to other systems, the present scalable solid-state strategy may open opportunity for the general synthesis of a wide range of well-defined SMACs for diverse applications.

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Photocatalytic Cr(VI) elimination over BUC-21/N-K2Ti4O9 composites: Big differences in performance resulting from small differences in composition Xun Wang, Yu-Xuan Li, Xiao-Hong Yi, Chen Zhao, Peng Wang, Jiguang Deng, Chong-Chen Wang 2021, 42 (2):  259-270.  DOI: 10.1016/S1872-2067(20)63629-4 Abstract ( 130 )   HTML ( 7 )   PDF (4481KB) ( 481 )   Supporting Information A series of BUC-21/N-K2Ti4O9 composites (B1NX) were facilely fabricated from BUC-21 and N-K2Ti4O9 via ball-milling, and they were fully characterized using various techniques. The photocatalytic reduction of Cr(VI) over the B1NX composites was investigated systematically under various conditions, including different light sources, pH values, hole scavengers, and inorganic ions, in both real lake water and tap water. The BUC-21/N-K2Ti4O9 composites demonstrated remarkable photocatalytic Cr(VI) reduction performance, good reusability, and stability under both UV and white light irradiation. The introduction of N-K2Ti4O9 into BUC-21 not only broadened its light absorption region to white light, but also strongly inhibited the recombination of the photo-generated electrons and holes. Mechanisms of photocatalytic Cr(VI) reduction under both UV light and white light were proposed and verified by electrochemical measurements, active species capture experiments, and ESR measurements.

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Direct growth of holey Fe3O4-coupled Ni(OH)2 sheets on nickel foam for the oxygen evolution reaction Yu Ding, Bo-Qiang Miao, Yue Zhao, Fu-Min Li, Yu-Cheng Jiang, Shu-Ni Li, Yu Chen 2021, 42 (2):  271-278.  DOI: 10.1016/S1872-2067(20)63639-7 Abstract ( 165 )   HTML ( 8 )   PDF (2690KB) ( 536 )   Supporting Information The oxygen evolution reaction (OER) is a half-reaction of water electrolysis, and the OER performance of an electrocatalyst is significantly related to its energy conversion efficiency. Due to their high OER activity, transition metal-based nanomaterials have become potential low-cost substitutes for Ir/Ru-based OER electrocatalysts in an alkaline environment. Herein, holey Fe3O4-coupled Ni(OH)2 sheets (Ni(OH)2-Fe H-STs) were easily achieved by a simple mixed-cyanogel hydrolysis strategy. The two-dimensional (2D) Ni(OH)2-Fe H-STs with ca. 1 nm thickness have a high specific surface area, abundant unsaturated coordination atoms, and numerous pores, which are highly favorable for electrocatalytic reactions. Meanwhile, the introduction of Fe improves the conductivity and regulates the electronic structure of Ni. Due to their special structural features and synergistic effect between the Fe and Ni atoms, Ni(OH)2-Fe H-STs with an optimal Ni/Fe ratio show excellent OER activity in a 1 M KOH solution, which significantly exceeds that of the commercial RuO2 nanoparticle electrocatalyst. Furthermore, Ni(OH)2-Fe H-STs can be grown on nickel foam (NF), and the resulting material exhibits enhanced OER activity, such as a small overpotential of 200 mV and a small Tafel slope of 56 mV dec-1, than that of Ni(OH)2-Fe H-STs without NF.

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Morphology evolution of acetic acid-modulated MIL-53(Fe) for efficient selective oxidation of H2S Xiaoxiao Zheng, Sihui Qi, Yanning Cao, Lijuan Shen, Chaktong Au, Lilong Jiang 2021, 42 (2):  279-287.  DOI: 10.1016/S1872-2067(20)63625-7 Abstract ( 179 )   HTML ( 9 )   PDF (1585KB) ( 582 )   Supporting Information MIL-53(Fe) was synthesized using a “modulator approach” that utilizes acetic acid (HAc) as an additive to control the size and morphology of the resulting crystals. We demonstrate that after activation under vaccum at 100 °C, the MIL-53(Fe) functions well for H2S selective oxidation. The introduction of acetic acid in the presence of benzene-1,4-dicarboxylic acid (H2BDC) would result in a series of MIL-53(Fe) nanocrystals (denoted as MIL-53(Fe)-xH, x stands for the volume of added HAc with morphology evoluting from irregular particles to short hexagonal columns. The vacuum treatment facilitates the removal of acetate groups, thus generating Fe 3+ Lewis acid sites. Consequently, the resulted MIL-53(Fe)-xH exhibits good catalytic activity (98% H2S conversion and 92% sulfur selectivity ) at moderate reaction temperatures (100-190 °C). The MIL-53(Fe)-5H is superior to the traditional iron-based catalysts, showing stable performance in a test period of 55 h.

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Orbital symmetry matching: Achieving superior nitrogen reduction reaction over single-atom catalysts anchored on Mxene substrates Jiale Qu, Jiewen Xiao, Hetian Chen, Xiaopeng Liu, Tianshuai Wang, Qianfan Zhang 2021, 42 (2):  288-296.  DOI: 10.1016/S1872-2067(20)63643-9 Abstract ( 250 )   HTML ( 18 )   PDF (3511KB) ( 390 )   Supporting Information The nitrogen reduction reaction (NRR) under ambient conditions is still challenging due to the inertness of N2. Herein, we report a series of superior NRR catalysts identified by examining Ti2NO2 MXenes embedded with 28 different single-atom catalysts using first-principles calculations. The stability of this system was first verified using formation energies, and it is discovered that N2 can be effectively adsorbed due to the synergistic effect between single atom catalysis and the Ti atoms. Examination of the electronic structure demonstrated that this design satisfies orbital symmetry matching where “acceptor-donor” interaction scenario can be realized. A new “enzymatic-distal” reaction mechanism that is a mixture of the enzymatic and distal pathways was also discovered. Among all of the candidates, Ni anchored on MXene system achieves an onset potential as low as -0.13 V, which to the best of our knowledge is the lowest onset potential value reported to date. This work elucidates the significance of orbital symmetry matching and provides theoretical guidance for future studies.

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Honeycomb-structured solid acid catalysts fabricated via the swelling-induced self-assembly of acidic poly(ionic liquid)s for highly efficient hydrolysis reactions Bihua Chen, Tong Ding, Xi Deng, Xin Wang, Dawei Zhang, Sanguan Ma, Yongya Zhang, Bing Ni, Guohua Gao 2021, 42 (2):  297-309.  DOI: 10.1016/S1872-2067(20)63658-0 Abstract ( 135 )   HTML ( 5 )   PDF (1687KB) ( 276 )   Supporting Information The development of heterogeneous acid catalysts with higher activity than homogeneous acid catalysts is critical and still challenging. In this study, acidic poly(ionic liquid)s with swelling ability (SAPILs) were designed and synthesized via the free radical copolymerization of ionic liquid monomers, sodium p-styrenesulfonate, and crosslinkers, followed by acidification. The 31P nuclear magnetic resonance chemical shifts of adsorbed trimethylphosphine oxide indicated that the synthesized SAPILs presented moderate and single acid strength. The thermogravimetric analysis results in the temperature range of 300-345 °C revealed that the synthesized SAPILs were more stable than the commercial resin Amberlite IR-120(H) (245 °C). Cryogenic scanning electron microscopy testing demonstrated that SAPILs presented unique three-dimensional (3D) honeycomb structure in water, which was ascribed to the swelling-induced self-assembly of the molecules. Moreover, we used SAPILs with micron-sized honeycomb structure in water as catalysts for the hydrolysis of cyclohexyl acetate to cyclohexanol, and determined that their catalytic activity was much higher than that of homogeneous acid catalysts. The equilibrium concentrations of all reaction components inside and outside the synthesized SAPILs were quantitatively analyzed using a series of simulated reaction mixtures. Depending on the reaction mixture, the concentration of cyclohexyl acetate inside SAPIL-1 was 7.5-23.3 times higher than that outside of it, which suggested the high enrichment ability of SAPILs for cyclohexyl acetate. The excellent catalytic performance of SAPILs was attributed to their 3D honeycomb structure in water and high enrichment ability for cyclohexyl acetate, which opened up new avenues for designing highly efficient heterogeneous acid catalysts that could eventually replace conventional homogeneous acid catalysts.

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Selective photocatalytic reduction of CO2 to CO mediated by a [FeFe]-hydrogenase model with a 1,2-phenylene S-to-S bridge Minglun Cheng, Xiongfei Zhang, Yong Zhu, Mei Wang 2021, 42 (2):  310-319.  DOI: 10.1016/S1872-2067(20)63644-0 Abstract ( 137 )   HTML ( 8 )   PDF (952KB) ( 425 )   Photocatalytic reduction of CO2 to CO is a promising approach for storing solar energy in chemicals and mitigating the greenhouse effect of CO2. Our recent studies revealed that [(μ-bdt)Fe2(CO)6] (1, bdt = benzene-1,2-dithiolato), a [FeFe]-hydrogenase model with a rigid and conjugate S-to-S bridge, was catalytically active for the selective photochemical reduction of CO2 to CO, while its analogous complex [(μ-edt)Fe2(CO)6] (2, edt = ethane-1,2-dithiolato) was inactive. In this study, it was found that the turnover number of 1 for CO evolution reached 710 for the 1/[Ru(bpy)3]2+/BIH (BIH = 1,3-dimethyl-2-phenyl-2,3-dihydro-1H-benzo[d]-imidazole) system under optimal conditions over 4.5 h of visible-light irradiation, with a turnover frequency of 7.12 min-1 in the first hour, a high selectivity of 97% for CO, and an internal quantum yield of 2.8%. Interestingly, the catalytic selectivity of 1 can be adjusted and even completely switched in a facile manner between the photochemical reductions of CO2 to CO and of protons to H2 simply by adding different amounts of triethanolamine to the catalytic system. The electron transfer in the photocatalytic system was studied by steady-state fluorescence and transient absorption spectroscopy, and a plausible mechanism for the photocatalytic reaction was proposed.

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Small-sized cuprous oxide species on silica boost acrolein formation via selective oxidation of propylene Ling-Ling Guo, Jing Yu, Wei-Wei Wang, Jia-Xu Liu, Hong-Chen Guo, Chao Ma, Chun-Jiang Jia, Jun-Xiang Chen, Rui Si 2021, 42 (2):  320-333.  DOI: 10.1016/S1872-2067(20)63636-1 Abstract ( 194 )   HTML ( 4 )   PDF (3283KB) ( 327 )   Supporting Information Oxide-supported copper-containing materials have attracted considerable research attention as promising candidates for acrolein formation. Nevertheless, the elucidation of the structure-performance relationships for these systems remains a scientific challenge. In this work, copper oxide clusters deposited on a high-surface-area silica support were synthesized via a deposition-precipitation approach and exhibited remarkable catalytic reactivity (up to 25.5% conversion and 66.8% selectivity) in the propylene-selective oxidation of acrolein at 300 °C. Aberration-corrected high-angle annular dark-field scanning transmission electron microscopy combined with X-ray absorption fine structure measurements of the catalyst before and after the reaction confirmed the transformation of the small-sized copper oxide (CuO) clusters into cuprous oxide (Cu2O) clusters. With the aid of in situ X-ray diffraction and in situ dual beam Fourier transform infrared spectroscopy (DB-FTIR), the allyl intermediate (CH2=CHCH2*) was clearly observed, along with the as-formed Cu2O species. The intermediate can react with oxygen atoms from neighboring Cu2O species to form acrolein during the catalytic process, and the small-sized Cu2O clusters play a crucial role in the generation of acrolein via the selective oxidation of propylene.

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Acetylene hydrochlorination over supported ionic liquid phase (SILP) gold-based catalyst: Stabilization of cationic Au species via chemical activation of hydrogen chloride and corresponding mechanisms Jia Zhao, Saisai Wang, Bolin Wang, Yuxue Yue, Chunxiao Jin, Jinyue Lu, Zheng Fang, Xiangxue Pang, Feng Feng, Lingling Guo, Zhiyan Pan, Xiaonian Li 2021, 42 (2):  334-346.  DOI: 10.1016/S1872-2067(20)63617-8 Abstract ( 209 )   HTML ( 5 )   PDF (5838KB) ( 398 )   Supporting Information The activation of HCl by cationic Au in the presence of C2H2 is important for the construction of active Au sites and in acetylene hydrochlorination. Here, we report a strategy for activating HCl by the Au-based supported ionic liquid phase (Au-SILP) technology with the [N(CN)2-] anion. This strategy enables HCl to accept electrons from [N(CN)2-] anions in Au-[N(CN)2-] complexes rather than from pure [Bmim][N(CN)2], leading to notable improvement in both the reaction path and the stability of the catalyst without changing the reaction triggered by acetylene adsorption. Furthermore, the induction period of the Au-SILP catalyst was shown to be absent in the reaction process due to the high Au(III) content in the Au(III)/Au(I) site and the high substrate diffusion rate in the ionic liquid layer. This work provides a facile method to improve the stability of Au-based catalysts for acetylene hydrochlorination.

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Complete removal of phenolic contaminants from bismuth-modified TiO2 single-crystal photocatalysts Wenjie Tang, Juanrong Chen, Zhengliang Yin, Weichen Sheng, Fengjian Lin, Hui Xu, Shunsheng Cao 2021, 42 (2):  347-355.  DOI: 10.1016/S1872-2067(20)63668-3 Abstract ( 128 )   HTML ( 6 )   PDF (2197KB) ( 301 )   Exploring low-cost and highly active photocatalysts is very urgent to accomplish complete removal of phenolic contaminants and overcome the limitations of the existing photocatalysts. In this study, we designed and synthesized noble metal-free TiO2 photocatalysts by introducing bismuth nanoparticles as modifiers of a TiO2 single crystal (Bi-SCTiO2). The Bi-SCTiO2 can make full use of the synergistic effect of a small band overlap and low charge carrier density (Bi) with a high conductivity (single crystal), significantly boosting the separation and migration of the photogenerated charge pairs. Therefore, the Bi-SCTiO2 photocatalyst exhibits a significantly enhanced degradation rate (12 times faster) of 4-nitrophenol than a TiO2 single crystal under simulated sunlight irradiation. Notably, the complete removal of phenolic contaminants is achieved in various water matrices, which not only successfully overcomes the incomplete degradation in many reported photocatalytic systems, but also manifests a significant practical potential for sewage disposal. Therefore, this work presents a new insight in designing and constructing noble metal-free decorated semiconductor single-crystal photocatalysts with excellent activity and cyclability.

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Solvothermal synthesis of Co-substituted phosphomolybdate acid encapsulated in the UiO-66 framework for catalytic application in olefin epoxidation Dianwen Hu, Xiaojing Song, Shujie Wu, Xiaotong Yang, Hao Zhang, Xinyu Chang, Mingjun Jia 2021, 42 (2):  356-366.  DOI: 10.1016/S1872-2067(20)63665-8 Abstract ( 376 )   HTML ( 13 )   PDF (1401KB) ( 438 )   Supporting Information Hybrid composites of phosphomolybdic acid@UiO-66 (PMo12@UiO-66) and Co-substituted phosphomolybdic acid@UiO-66 (PMo11Co@UiO-66) were synthesized using the direct solvothermal method. A variety of characterization results demonstrated that phosphomolybdic acid (PMo12) or Co-substituted phosphomolybdate acid (PMo11Co) clusters are uniformly dispersed in the cages of Zr-based metal-organic UiO-66 frameworks. The catalytic properties of these hybrid composites were investigated by applying the epoxidation of olefins with tert-butyl hydroperoxide as the oxidant. Compared to PMo12@UiO-66, PMo11Co@UiO-66 showed a much higher catalytic activity and was simply recovered by filtration and reused for at least ten runs without significant loss of catalytic activity. Particularly, PMo11Co@UiO-66 can efficiently convert cyclic olefins like limonenes to epoxides, and its selectivity to 1,2-limonene oxide reached 91% in the presence of a radical inhibitor such as hydroquinone. The excellent catalytic activity and stability of the hybrid composite PMo11Co@UiO-66 are mainly attributed to the uniform distribution of highly active PMo11Co units within the smaller cages of UiO-66, to the suitable surface polarity of the hybrid composite for facilitating the access of reagents and solvent, and to the strong interface-interactions between the polyoxometalate and the UiO-66 framework.