Density Functional Theory Study on the Metal-Support Interaction between Ru Cluster and Anatase TiO2(101) Surface

Density functional theory (DFT) calculations were carried out to study the nucleation and growth mechanism of Ru clusters on the TiO2(101) surface by using supported Ru (n = 1-10, 20, 22) cluster models to understand the metal-support interaction and the resulting catalytic performance toward CO oxidation. The results show that the Ru-n cluster prefers a 3D geometry when n >= 4 and that the Ru TiO2 interface is predominantly composed of Ru-O and Ti-O bonds. Calculation studies based on the density of states (DOS), Hirshfeld charge analysis, and electron deformation density (EDD) demonstrate that the electronic interaction is mainly localized at the Ru-TiO2 interface through the electron transfer via the Ru-O bond. Additionally, the investigation on catalytic behavior of Ru-n/TiO2 toward CO oxidation reveals the largely enhanced catalytic activity of the supported Ru-n clusters, which originates from the significant reduction of the activation barrier as a result of the electron transfer from Ru to TiO2.