Effect of Electronic Structures of Au Clusters Stabilized by Poly(N-vinyl-2-pyrrolidone) on Aerobic Oxidation Catalysis
Effect of Electronic Structures of Au Clusters Stabilized by Poly(N-vinyl-2-pyrrolidone) on Aerobic Oxidation Catalysis
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DOI：
10.1021/ja810045y
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发表时间：
2009-05-27
影响因子：
15
通讯作者：
Tsukuda, Tatsuya
中科院分区：
文献类型：
--
作者：
Tsunoyama, Hironori;Ichikuni, Nobuyuki;Tsukuda, Tatsuya
小于1.5 nm的Au团簇经聚乙烯吡咯烷酮（PVP）稳定后对乙醇的催化氧化活性高于较大尺寸的团簇或经聚烯丙胺（PAA）稳定后的团簇。X射线光电子能谱、吸附CO的傅里叶变换红外光谱和X射线吸收近边结构测量表明，催化活性的Au团簇由于PVP的电子贡献而带负电荷，催化活性随着Au核上电子密度的增加而增强。基于对气相中Au团簇阴离子的类似观察，我们提出电子从Au：PVP的阴离子Au核转移到O-2的LUMO（pi*）中产生了超氧或类过氧物种，这在醇的氧化中起着关键作用.在此基础上，提出了一种简单的有机分子稳定的Au氧化催化剂的合成原理。
Au clusters smaller than 1.5 nm and stabilized by poly(N-vinyl-2-pyrrolidone) (PVP) showed higher activity for aerobic oxidation of alcohol than those of larger size or stabilized by poly(allylamine) (PAA). X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy of adsorbed CO, and X-ray absorption near edge structure measurements revealed that the catalytically active Au clusters are negatively charged by electron donation from PVP, and the catalytic activity is enhanced with increasing electron density on the Au core. Based on similar observations of Au cluster anions in the gas phase, we propose that electron transfer from the anionic Au cores of Au:PVP into the LUMO (pi*) of O-2 generates superoxoor peroxo-like species, which plays a key role in the oxidation of alcohol. On the basis of these results, a simple principle is presented for the synthesis of Au oxidation catalysts stabilized by organic molecules.