Enhanced visible light photocatalytic activity of Cu2O via cationic-anionic passivated codoping

To improve the photocatalytic activity of Cu2O for hydrogen production through water splitting, the band edges of Cu2O should be modified to meet the electronic transition of angular momentum selection rules (Δl = ±1) and match with the hydrogen or oxygen production levels. Upon analyzing the band structure of Cu2O and the chemical potentials of the dopants, we show that passivated codopants such as (Sn + B) can induce superior modification in the band edges of Cu2O: the conduction band edge is changed from the d band character of Cu atoms to the p band character of the Sn atom and shifted slightly downwards, while the valence band edge keeps the d band character of the Cu atoms and energy unchanged, indicating that the stringent requirements get satisfied. Moreover, the optical absorption spectrum of (Sn + B) codoped Cu2O shows a greatly improved absorption of visible light. The calculated defect formation energy shows that the codoping is energetically more favorable than mono-doping due to the Coulomb interactions and charge compensation effects.