Oxidic structures on copper-gold alloy nanofacets

Bimetallic alloy catalysts often display superior performance to their monometallic counterparts in numerous chemical reactions, whose reactivity and selectivity primarily depend on their surface structures and chemical compositions under reaction environments. Predicting the structure and composition of alloy surfaces under reaction conditions is still challenging. In this work, using density-functional theory with ab initio thermodynamics, we examine the surface structures of the Cu-Au alloy system under different preparation and oxidative environments. We analyze the stability of thin copper oxide layers on various substrates, ranging from clean Au(111) to Au3Cu and their mixtures, and Cu overlayer structures. Our results show that the stability of the oxide layer structures strongly depend on the atomic configurations of the substrate. We also explore the possibility of using computational surface characterization methods to capture the atomic configurations and electronic structure of different interfacial regions of these substrates. Our electronic structure analysis demonstrates that controlling the concentration of surface Cu allows one to fine tune the surface electronic structure, and modulating the growth conditions to express the desired surface oxide phase may achieve the same effect. By providing an atomic-scale account, this study aims to capture the atomic configurations and electronic structure of different interfacial regions of these complex oxidic Cu/Au nanoalloys for selective oxidation reactions.