Nature and Role of Activated Molecular Oxygen Species at the Gold/Titania Interface in the Selective Oxidation of Alcohols

The heterogeneously catalyzed selective oxidation of alcohols has been studied by using methanol on gold nanoparticles supported on reduced titania surfaces. Our density functional theory based simulations shed light on the atomistic details of the mechanism responsible for the CH3OH oxidation toward formaldehyde, CH2O, at these complex Au/TiO2 interfaces. The selectivity and high catalytic activity of the Au/TiO2 nanocatalyst in the oxidation of methanol is traced back to the presence of active sites right at the interface between the Au nanoparticle and the TiO2 support where preadsorbed molecular oxygen is activated as a result of significant metalsupport interactions. The activation of O-2 at such dual perimeter sites occurs via charge transfer from Au/TiO2 leading to the formation of peroxide species, O-2(delta-). These activated O-2(delta-) species open up an efficient low-temperature reaction channel for the oxidation of methanol to yield formaldehyde and water.