One-pot construction of robust BiOCl/ZnO p-n heterojunctions with semi-coherent interfaces toward improving charge separation for photodegradation enhancement.

Heterojunction engineering is an effective strategy to enhance the photodegradation activity improving the spatial charge separation. However, the poor interface interactions and stability limit the photocatalytic activity and stability of traditional heterojunctions. Herein, robust BiOCl/ZnO p-n heterojunctions with semi-coherent interfaces were prepared by a one-pot hydrothermal method to improve the activity and stability toward photocatalytic degradation than that of the counterpart, in which the semi-coherent interfaces exhibited lower phase boundary energy, resulting in highly-stable interfaces between BiOCl and ZnO as well as the formation of the built-in electric field in this robust p-n heterojunction for enhanced charge separation. The cycle test results verified that the BiOCl/ZnO heterojunctions with semi-coherent interfaces can maintain the photocatalytic degradation activity at the initial level even after 10 cycles, while deactivation of the sample without semi-coherent interfaces occurred after 3 cycles only. Optical and electrical properties revealed that BiOCl/ZnO heterojunctions with semi-coherent interfaces possessed the highest electron migration and charge separation efficiency, resulting in the highest photodegradation activity. Density functional theory (DFT) calculations and electron spin-resonance (ESR) results verified that the enhanced charge separation was assigned to the type-II photocatalytic mechanism, leading to the enhancement of ˙OH and ˙O reactive oxygen species. This work would provoke the development of one-step construction of new highly active BiOX (X = Cl, Br, and I)-based heterogeneous photocatalysts with stable semi-coherent interfaces.