The effect of rutile TiO2(110) surface on the physicochemical properties of subnanometer Au–Pd clusters: A DFT study

Abstract

Bimetallic clusters are of particular interest in several applications due to the unique properties they exhibit as a result of the synergistic effect of their metals. In addition, the substrate can alter the structure and stability of these clusters by means of cluster–support interactions. In this work, we study the physicochemical properties of Au–Pd/TiO2(110) supported clusters via density functional theory (DFT) calculations. The effect of surface TiO2(110) on the structural and energetic properties of Au–Pd clusters is relevant. The cohesion energy depends on both metal–metal and metal–support interactions. Au and Au-rich bimetallic clusters change their gas phase configuration upon adsorption. Some clusters do not fit well on the surface, resulting in decreased stability. By contrast, pure Pd and Pd-rich bimetallic clusters have the highest adsorption energies and charge polarization due to the cluster–surface interaction. These clusters exhibit elongation in the metal–metal bonds and redshifts in their vibrations. The Bader charge analysis shows that Au–Pd clusters donate charge to the surface, thus becoming positively charged. Finally, the TiO2(110) surface induces stiffness in the clusters, since the supported clusters do not exhibit low-frequency vibrations like their gas-phase analogs.