Aun (n = 1–16) clusters on the ZrO2(111) surface: a DFT+U investigation
The growth patterns and electronic structures of Aun clusters (n = 1–16) supported on the monoclinic ZrO2(111) surface were investigated using a DFT+U approach. We found that the supported Aun 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 Aun cluster and the ZrO2 surface. Electrons were transferred from the ZrO2 surface to the Aun cluster. Small energy gaps between unoccupied states in the Aun clusters and occupied states in the ZrO2 surface were found, especially for the supported Aun clusters with odd n, which may indicate that more electrons are excited from the ZrO2 surface to the Aun cluster even under visible-light irradiation. In other words, the ZrO2 support may be involved in the photocatalytic process when Aun/ZrO2 is used as a photocatalyst.