Au_n (n = 1-16) clusters on the ZrO₂(111) surface: a DFT+U investigation

The growth patterns and electronic structures of Au_n clusters (n = 1-16) supported on the monoclinic ZrO₂(111) surface were investigated using a DFT+U approach. We found that the supported Au_n clusters prefer quasi-planar structures and lay flat on the ZrO₂ surface. This result agrees well with the experimental results. Both orbital overlap and dispersion interactions contribute to the interaction between the Au_n cluster and the ZrO₂ surface. Electrons were transferred from the ZrO₂ surface to the Au_n cluster. Small energy gaps between unoccupied states in the Au_n clusters and occupied states in the ZrO₂ surface were found, especially for the supported Au_n clusters with odd n, which may indicate that more electrons are excited from the ZrO₂ surface to the Au_n cluster even under visible-light irradiation. In other words, the ZrO₂ support may be involved in the photocatalytic process when Au_n/ZrO₂ is used as a photocatalyst.