Insights into the H2O/V2O5 Interface Structure for Optimizing Water-splitting

The interaction of water (H2O) with metal oxide surfaces is of fundamental importance to various fields of science, ranging from batteries to catalysis. In particular, vanadium pentoxide (V2O5) has been widely used as electrode materials for aqueous-battery and catalysts. Herein, theoretical (density functional theory) study gives atomic-scale insights into water monolayers in V2O5 and single-molecule adsorption and dissociation at three low-index surfaces and oxygen-vacancy V2O5(001) surface. The H2O/V2O5 interface structure was identified. The results show that H2O is adsorbed on the stoichiometric V2O5 (001) surface with physisorption mechanism, and the dissociation hardly occurs. Water adsorbs as an intact monomer with a computed binding energy of 0.75 eV. The formation of ordered water overlayers has been observed on V2O5(001) surface, suggesting a locally ordered superstructure of molecular water. The molecular H2O adsorption on oxygen-vacancyV(2)O(5)(001) surface is stronger than that on the stoichiometric V2O5(001) surface, and H2O can undergo dissociative chemisorption to form a surface hydroxyl group and a H adatom. V2O5 can take the oxygen from H2O, which is consistent with the experimental results.