J. Mat. Chem. A. 2018, 6, 24965-24970.

Bismuth vanadate (BiVO4) is one of the most promising materials for photoelectrochemical water splitting, with recent work highlighting the improved photocatalytic activity of quantum-sized BiVO4 compared with the crystalline phase. Herein, we report a theoretical investigation of the structural, optical and catalytic properties of BiVO4 clusters through a combination of density functional theory methods (ab initio molecular dynamics, time-dependent density functional theory, transition state theory). The enhanced solar water oxidation efficiency of BiVO4 nanoclusters is linked with the localization of spin density on the ionized cluster surface, and the dramatic reduction, compared with the crystalline BiVO4 phase, of the Gibbs free energy of activation and reaction associated with the hydrogen transfer process between water and BiVO4. Our results illustrate the main effects associated with the reduction of dimensions (from bulk to quantum-size) on the main steps of water oxidation mechanisms. This understanding can contribute to the design of efficient BiVO4 quantum-sized water-splitting photocatalysts.