Oxidic copper on the Au(111) surface:A theoretical surface science approach

Recently, via reactive Cu deposition in an oxygen ambience, high quality gold-supported cuprous oxide (Cu$_2$O) ultrathin nanofilms [1] have been prepared as a model system to further such catalytic studies. Nonetheless, an accurate atomic picture of these ultrathin Cu$_2$O nanofilms, which largely depends on its immediate oxygen environment, is currently lacking. In this work, we perform density-functional theory (DFT) calculations using the Vienna ab initio Simulation Package in combination with \textit{ab initio} atomistic thermodynamics [2] to investigate stability of Cu$_2$O thin films on Au(111) as a function of oxygen chemical potential. Our results indeed show that some of the surface structures suggested in Ref. [1] are energetically more stable than the traditional copper oxide thin film structures on copper substrate, and elucidated the electronic structure of these ultrathin copper oxide films on gold, in comparison with available experimental data. [1] H. Str\"{a}er et al., J. Phys. Chem. C 119, 5975 (2015); [2] A. Soon et al., Phys. Rev. B 73, 165424 (2006)