Reactive Structural Motifs of Au Nanoclusters for Oxygen Activation and Subsequent CO Oxidation

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• 作者：Hyesung An ; Soonho Kwon ; Hyunwoo Ha ; Hyun You Kim ; Hyuck Mo Lee
• 刊名：Journal of Physical Chemistry C
• 出版年：2016
• 出版时间：May 5, 2016
• 年：2016
• 卷：120
• 期：17
• 页码：9292-9298
• 全文大小：430K
• 年卷期：0
• ISSN：1932-7455

文摘

Understanding the size-dependent oxygen affinity of small Au nanoparticles (NPs) and nanoclusters (NCs) is central to the rational design of Au oxidation catalysts. However, relevant complete experimental or computational information on the intrinsic catalytic nature of Au NPs/NCs is scarce. Here, to provide fundamental insights into the intrinsic size- and coordination-dependent catalytic nature of free-standing small Au NPs/NCs for oxidation reactions, we constructed small unsupported Au_n (n = 1–10, 13, 19, 20, 25, 38, and 55) NCs and scrutinized their oxygen-adsorption chemistry and corresponding CO oxidation activity using density functional theory (DFT) calculations. Strong oxygen binding to Au_n NCs is essential for facile CO oxidation. Among our studied Au NCs, only the tiny Au₃, Au₅, and Au₇ NCs strongly bound O₂ and CO. The subsequent CO oxidation pathways studied by DFT confirmed that Au₅ exhibited the highest CO oxidation rate among the studied Au NCs. We observed that only highly limited, tiny Au NCs with a specific structural motif can catalyze CO oxidation themselves. We observed that a delicate balance between the energy of CO adsorption and that of O₂ adsorption is required to maximize the catalytic activity of Au NCs with respect to CO oxidation.