Visible light-driven type II p-Bi3O4Cl/n-BiPO4 heterojunction for effective photocatalytic photodegradation

Removing persistent organic effluents from water through photocatalytic using visible light is a promising avenue of research. However, due to its broad band gap, BiPO4 can only respond to ultraviolet radiation. In this work, we have succeeded in forming a novel type II p-Bi3O4Cl/n-BiPO4 heterojunction by a simple solid-state reaction. This heterojunction enhances the efficiency of migration and separation of photogenerated charge carriers and subsequently improves the photocatalytic activity of BiPO4 under visible light irradiation. The photocatalytic activities of BiPO4 and Bi3O4Cl increased by 61- and 4-fold, respectively, during 2 h of visible light irradiation for RhB degradation. The decomposition mechanism behind the improved rates is discussed based on trapping experiments, optical, electrochemical and photoluminescent findings. Furthermore, we assessed the stability and regeneration efficiency of the p-Bi3O4Cl/n-BiPO4 heterojunction photocatalyst through five photocatalytic cycles.