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

Abstract

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.