First-principles calculations of water adsorption on perfect and defect WO3(0 0 1)

Abstract

The interactions between water and semiconductor metal oxides are critical to photocatalytic reactions. In this work, the water adsorption on stoichiometric, non-stoichiometric and hydrogenated WO3(0 0 1) were investigated by first-principles calculations. The results show that the adsorption of the intact water molecule is more favorable than the adsorption of the dissociated ones on stoichiometric WO3(0 0 1) at different coverages. As the coverage of the water molecules on the surface increases, the molecular and dissociated states tend to co-exist on the stoichiometric WO3(0 0 1). In addition, the oxygen vacancy and hydrogen atom affect the electronic properties of WO3(0 0 1) by introducing the excess electrons, and the water adsorption could change distribution of excess electrons which are introduced by oxygen vacancy and hydrogen atoms. The water molecule can readily dissociate at the surface oxygen vacancy sites, while water molecules prefer remaining intact than being dissociated on the WO3(0 0 1) with sub-surface oxygen vacancy or hydrogen.