Preparation of double-vacancy modified carbon nitride to greatly improve the activity of photocatalytic hydrogen generation

Vacancy engineering has been a very active research area in the field of photocatalysis. The electronic/band structure of carbon nitride can be tuned by introducing vacancies. However, the hydrogen production rate of carbon nitride modified only by a single defect is not significant. Therefore, we have constructed nitrogen-oxygen double vacancy modified carbon nitride by a simple two-step method. Especially, the photocatalytic performance of DACN-2 was 11.7 times and 5.8 times better than that of carbon nitride and oxygen-doped carbon nitride, respectively. The increase of specific surface area along with more available active sites, the pull-up of conduction band position and more efficient separation of photogenerated electron-hole pairs accounted for the improvement of hydrogen evolution performance. Moreover, the double vacancy was the separation center of the photogenerated charges, which accelerated the separation of photogenerated electrons and holes. This research provided a new concept for the design of defective carbon nitride and laid the foundation for the development of more effective photocatalysts in the future.