Cu2O-CuX NPs rich in oxygen vacancies modulated by halogen ions and its applications in photocatalytic degradation

Oxygen vacancies (OVs) are one of the most important strategies to modulate the photocatalytic properties of nanomaterials, but usually the preparation of OVs is complicated and difficult, so the development of a simple, gentle, and efficient method to prepare OVs is crucial. Herein, Cu/Cu₂O NPs with a small number of OVs were prepared by one-step reduction method at first. Then with the addition of halogen ions (F^–, Cl^–, Br^–, and I^–), Cu₂O-CuX NPs enriched with OVs were prepared at room temperature. And the effects of the addition of the halogen ions were analyzed. Cu₂O-CuF₂ NPs had the highest content of OVs, which enables efficient photocatalytic degradation of methylene blue (MB). Compared with Cu/Cu₂O NPs, Cu₂O-CuX NPs exhibit higher OVs content, narrower band gaps, and significantly improved photocurrent signal. These findings suggest that the introduction of halogen ions promotes the efficiency of light collection and charge carrier separation, and thus improving the degradation of MB. This work might open up new avenues for the design of superior photocatalysts for dealing with organic contaminants through OVs engineering.