Theoretical insight into the electronic and photocatalytic properties of Cu2O from a hybrid density functional theory

Abstract A comprehensive first-principle investigation, based on hybrid density functional theory, produces strong evidence that the Cu 2 O band-edges do satisfy the requirements of the H + /H 2 and O 2 /H 2 O redox levels, demonstrating that it has enough driving force for photocatalytic overall water splitting. The calculated band gap of Cu 2 O is 2.184 eV, which is consistent with the experimental value of 2.17 eV. The highly dispersive s – s hybrid states at the conduction band bottom result in a small effective mass of the electron, which is favorable to carrier separation and the carrier transfer to surface, and thus facilitate the reduction of H + to H 2 . The strong optical absorption of Cu 2 O is beneficial to overall water splitting under visible light irradiation. Possible reasons for no observation of H 2 in some experiments are also discussed. The results address the ongoing controversy associated with photocatalytic overall water splitting of Cu 2 O.