The growth pattern and electronic structures of Cun(n = 1–14) clusters on rutile TiO2(1 1 0) surface

Abstract

The growth pattern and electronic properties of Cun (n = 1–14) clusters supported on rutile TiO2(110) surface have been studied by using the density functional theory method. The calculation results showed that the supported Cun (n = 3–5,7) clusters prefer planar or quasi-planar structures, while Cun (n = 6,8–14) clusters prefer three-dimensional structures. The stabilities of Cun/TiO2 show an odd–even oscillation behavior with the increasing n, except n = 2 and 7. For the supported Cun, the clusters with odd n are more stable than the adjacent clusters. The charge transfer from Cun clusters to TiO2 surface was observed. The electron densities of Cu atoms adjacent to O atoms of the surface are obviously reduced. Electronic structure analysis indicated: (1) Electrons are transferred from Cun clusters to the valence band of TiO2 surface. (2) The states from Cun clusters appear in the energy gap of the TiO2 surface and the energy gaps between the occupied states from Cun clusters and the unoccupied states from TiO2 surface decrease with the increasing n. Our calculations showed that the visible light irradiation can further enhance the charge transfer from the Cun clusters (with diameter smaller than 0.6 nm) to TiO2 surface and facilitate the reduction reactions (such as CO2 reduction reaction) on the TiO2 surface.