Systematic characterization of metal-supported ultrathin copper oxide layers from first-principles calculations*

The nanocatalyst system composed of thin copper oxide layers on different metal supports (e.g. gold) is gaining a lot of attention due to its exceptional performance in photochemical and oxidation reactions. The atomic configuration of the metal support is known to assist in the tuning of the overall electronic structure of the nanocatalyst system which, in turn, determines its catalytic properties. However, before turning our attention to the explicit physical structure of these metallic supports, we find that a systematic and thorough characterization of all supported Cu surface oxides is currently lacking and far from complete. Here, we survey and study the various possible ultrathin oxide structures of Cu using first-principles density-functional theory (DFT) calculations. Namely, we report the DFT-derived surface core-level shifts (CLS) and simulated scanning tunneling microscopy (STM) images (where the orbitals of the STM tip are explicitly considered) for O/Cu(111), ``29'', ``44'', ``8'', and other defect structures, and provide an atomistic picture to explain and interpret the structural ambiguities in recent CLS and STM experiments.