BiOCl/BiVO₄ p–n Heterojunction with Enhanced Photocatalytic Activity under Visible-Light Irradiation

Abstract

A novel visible-light-active BiOCl/BiVO4 photocatalyst with a p–n heterojunction structure was prepared using a hydrothermal method. The photocatalytic activity of the heterojunction was investigated by monitoring the change in methyl orange (MO) concentration under visible-light irradiation. The results reveal that the composite exhibited markedly improved efficiency for MO photodegradation in comparison with pure BiVO4, BiOCl, and Degussa P25. This is ascribed to the B-type heterojunction structure with a strong oxidative ability and efficient charge separation and transfer across the BiOCl/BiVO4 p–n junction. The highest activity was obtained in the BiOCl/BiVO4 heterojunction using a composite of 13 mol % BiOCl and 87 mol % BiVO4. The removal of MO was mainly initiated by valence-band holes, but dissolved oxygen also played a crucial role in consuming the conduction-band electrons. This was verified by the effects of scavengers and N2 purging.