Layered double hydroxides supported atomically precise Aun nanoclusters for air oxidation of benzyl alcohol: Effects of size and active site structure
Layered double hydroxides supported atomically precise Aun nanoclusters for air oxidation of benzyl alcohol: Effects of size and active site structure
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DOI：
10.1016/j.jcat.2020.06.017
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发表时间：
2020-06
影响因子：
7.3
通讯作者：
Yang Xu;Jin Li;Jian Zhou;Yufeng Liu;Zhu Wei;Hui Zhang
中科院分区：
文献类型：
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作者：
Yang Xu;Jin Li;Jian Zhou;Yufeng Liu;Zhu Wei;Hui Zhang
以苯甲醇空气氧化为反应体系，研究了Ni 3Al-LDH催化剂的尺寸和活性中心结构对催化活性的影响层状双金属氢氧化物负载纳米簇催化剂Aun/LDH（n = 25，38，~127），通过原子级精确的Au ~（25）Capt ~（18），Au ~（38）Capt ~（24）和Au~（127）-Capt的改进静电吸附获得（Capt：captopril）NC随后适当煅烧。详细的表征表明，Au 25/LDH、Au 38/LDH和Au~127/LDH分别具有1.2 ± 0.2、1.4 ± 0.3和1.8 ± 0.5 nm的超细Au纳米颗粒，这些纳米颗粒主要分散在小尺寸LDH纳米片（20-40 nm）的边缘位置。所有催化剂在无碱条件下对苯甲醇的空气氧化反应均表现出优异的催化活性，并具有明显的尺寸和活性中心结构依赖性。XPS、CO-DRIFTs和动力学同位素研究表明，Au 38/LDH催化剂具有最高的活性，TOF为1884 h-1，这可能是由于Au 38 NCs的超细双二十面体结构和最强的Au 38 NCs- Ni-OH（LDH）协同效应促进了苯甲醇的α-C单键H键的活化，而不是带更多负电荷的Au位点。负载型Auncluster催化剂在苯甲醇氧化反应中的尺寸和活性中心结构依赖性的研究结果为负载型Auncluster催化剂的合理设计提供了重要的指导原则。
The effects of size and active site structure on catalytic activity were deeply investigated in air oxidation of benzyl alcohol over a series of Ni3Al-LDH (layered double hydroxides)-supported Aunnanocluster (NC) catalysts Aun/LDH (n = 25, 38, ~127), obtained by modified electrostatic adsorption of atomically precise Au25Capt18, Au38Capt24and Au~127-Capt (Capt: captopril) NCs followed proper calcination. Detailed characterizations show that the Au25/LDH, Au38/LDH and Au~127/LDH possess ultrafine Au NCs size of 1.2 ± 0.2, 1.4 ± 0.3 and 1.8 ± 0.5 nm, respectively, which are majorly dispersed on the edge sites of the small-sized LDH nanosheets (20–40 nm). All the catalysts exhibit excellent catalytic activities in air oxidation of benzyl alcohol without external base associated with the remarkable size- and active site structure-dependence. The catalyst Au38/LDH shows the highest activity with TOF of 1884 h−1, which can be attributable to the ultrafine bi-icosahedron structure Au38NCs and the strongest Au38NCs – Ni-OH (LDH) synergistic effect facilitating the activation of α-Csingle bondH bond of benzyl alcohol over more negatively charged Au sites upon XPS, CO-DRIFTs and kinetic isotope studies. The findings of the size- and active site structure-dependence of supported Auncluster catalysts in the oxidation of benzyl alcohol provide important guiding principles for the rational design of supported Auncluster catalysts.