Solvation-Enhanced Oxygen Activation at Gold/Titania Nanocatalysts

Abstract

The precise impact of solvation in heterogeneously catalyzed reactions in aqueous solution still remains unclear. Using ab initio simulations where all system components, notably all water molecules, are included at the electronic structure level, we find that the activation free energy for O2 dissociation at gold nanoparticles on titania is decreased by as much as 25% in aqueous solution compared with the gas phase. This effect is traced back to an increased charge on the O2···gold/titania adsorption complex due to solvation by water, in addition to stabilization by protonation of the preactivated O2 thanks to autodissociation of interfacial water molecules.