Evolution of atomic and electronic structures of Cun (n = 2–10) clusters supported on anatase TiO2(1 0 1) surface

Abstract

Based on extensive structural search and density functional theory (DFT) calculations, the atomic and electronic structures of of Cun (n = 2–10) clusters supported on anatase TiO2(101) surface (denoted as Cun/A(101)) are systematically studied. The atomic structures exhibit obvious hereditary feature, i.e. most of the low-energy structures of larger clusters can be obtained by adding additional Cu atoms onto those of smaller clusters. Small sized clusters (n ≤ 6) prefer to quasi planar structures while large sized clusters (n > 6) prefer to complex three-dimensional structures. The thermodynamic stabilities of the supported Cun clusters are investigated by calculating the binding energies, second order energy difference, adsorption energies and nucleation energies. It is found that Cu3/A(101), Cu5/A(101), and Cu8/A(101) are particularly stable and Cu3, Cu5 and Cu9 clusters would be stabilized by the substrate mostly. All these Cun clusters can introduce in-gap states and reduce the band gaps according to the calculated density of states. Supported Cun clusters play the role of electron donor, resulting in partial oxidation state Cuδ+ and zero valence state Cu0.