First-principles study of Au nanostructures on rutileTiO2(110)

Abstract

We report systematic density-functional theory calculations of the structure and energetics of ${\text{Au}}_{n}$ nanorows $(n=1--7)$ and clusters $(n=1--12)$ adsorbed on the defected (110) rutile surface. The calculations show that gold nanorows bind strongly to a missing-row defected ${\text{TiO}}_{2}$ surface with an adhesive binding energy of about 1.5 eV. The cohesive binding energy of Au atoms in a row amounts to about 2.5 eV/atom. An analysis of the gold row properties points to their metallic nature. The charge redistribution on adsorbed rows shows that all ${\text{Au}}_{n}$ rows are negatively charged compared to the free-standing structures. The adhesive bonding of gold clusters to the vacancy defected bridging oxygen row at the ${\text{TiO}}_{2}(110)$ is of covalent nature and is stronger than that of the Au rows. The cohesive energy per atom in a ${\text{Au}}_{n}$ cluster is about 2.2 eV for the $n\ensuremath{\ge}5$ clusters and is larger $(\ensuremath{\sim}2.3--2.4\text{ }\text{eV})$ for smaller ones. We found that all clusters studied are negatively charged with about 1.1 electron charge. This charging shows only a weak dependence on the odd-even number of gold atoms forming a cluster.