Theoretical study of water adsorption and dissociation on Ta3N5(100) surfaces

Abstract

Water adsorption and dissociation on the perfect, oxygen containing and nitrogen vacancy containing Ta₃N₅(100) surfaces are systematically studied by density functional theory calculations. The results show that the perfect Ta₃N₅(100) surface is very active for water dissociation because of the dangling bonds formed on the perfect Ta₃N₅(100) surface. The presence of oxygen on the surface is able to stabilize the Ta₃N₅(100) surface but not to facilitate water dissociation, which may be ascribed to the saturation of surface dangling bonds by oxygen. The presence of a nitrogen vacancy on the surface is able to facilitate water dissociation, but Ta₃N₅(100) surfaces with nitrogen vacancies are not stable. We found that keeping the impurity oxygen as less as possible is one effective approach to enhance the water splitting ability of Ta₃N₅. We propose that doping with foreign elements is one potential method to obtain a clean Ta₃N₅(100) surface, since the oxygen concentration may be adjusted by competition between oxygen and foreign elements.