Structure, Redox Chemistry, and Interfacial Alloy Formation in Monolayer and Multilayer Cu/Au(111) Model Catalysts for CO2 Electroreduction

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• 作者：Daniel Friebel ; Felix Mbuga ; Srivats Rajasekaran ; Daniel J. Miller ; Hirohito Ogasawara ; Roberto Alonso-Mori ; Dimosthenis Sokaras ; Dennis Nordlund ; Tsu-Chien Weng ; Anders Nilsson
• 刊名：Journal of Physical Chemistry C
• 出版年：2014
• 出版时间：April 17, 2014
• 年：2014
• 卷：118
• 期：15
• 页码：7954-7961
• 全文大小：412K
• 年卷期：v.118,no.15(April 17, 2014)
• ISSN：1932-7455

文摘

High-energy-resolution fluorescence-detection X-ray absorption spectroscopy (HERFD XAS) has been used to probe the geometric and electronic structure of a Cu monolayer model electrocatalyst as a function of applied potential in situ in alkaline electrolyte. In 0.01 M NaOH, a Cu monolayer deposited on an Au(111) single crystal exhibits markedly different redox behavior from Cu multilayers on the same substrate: the Cu monolayer is more stable against oxide formation and, at high potentials (E > 0.5 V vs RHE), undergoes a direct phase transition from Cu⁰ to CuO rather than forming an intermediate Cu₂O phase. The Cu monolayer in its metallic state at low potentials is expanded by 12.5% to match the substrate lattice constant, which can be expected to influence significantly the interaction of Cu surface atoms with intermediates of the electrochemical CO₂ reduction. However, we also find that both strained Cu monolayer and thick, structurally relaxed Cu islands are unstable with respect to place-exchange with subsurface Au atoms. Such segregation phenomena need to be carefully considered and can limit the applicability of lattice strain as independent catalyst design parameter.