Gold clusters on rutile were recalled to serve as efficient oxidation catalysts for pollutants and environmental contaminants. However, the mechanism by which highly mobile small clusters migrated and aggregated into larger species relevant to gold's catalytic activity remained unresolved. Here, ab initio simulations were made of the diffusion of atomic gold clusters up to the trimer on rutile (110) surfaces. It was shown that, at the stoichiometric surface, both the dimer and the trimer could exhibit relatively low surface mobility due to high energetic barriers for diffusion out of their energetic minima coupled with low barriers for the reverse motion. On the reduced surface, these clusters could diffuse relatively quickly between energetic minima within the oxygen vacancy site due to the large degree of vibrational entropy in their transition states.

Gold Cluster Diffusion Kinetics on Stoichiometric and Reduced Surfaces of Rutile TiO2(110). Goldman, N., Browning, N.D.: Journal of Physical Chemistry C, 2011, 115[23], 11611-7