Regulating nitrogen vacancies within graphitic carbon nitride to boost photocatalytic hydrogen peroxide production

Introducing nitrogen vacancies is an effective method to improve the catalytic performance of g‐C 3 N 4 ‐based photocatalysts, whereas understanding how nitrogen vacancies types affect the catalytic performance remains unclear. Herein, two different types of nitrogen vacancies were successfully introduced into g‐C 3 N 4 by pyrolysis of melamine under argon and ammonia atmosphere with subsequent HNO 3 oxidation. The pyrolysis atmosphere is found to have a significant influence on the introduced nitrogen vacancies type, where tertiary nitrogen groups (N 3 C) and sp 2 ‐hybridized nitrogen atoms (N 2 C) were the preferred sites for the formation of nitrogen vacancies under ammonia and argon pyrolysis, respectively. Moreover, nitrogen vacancies from N 3 C are experimentally and theoretically demonstrated to facilitate the narrowed band gap and the improved oxygen absorption capability. As expected, the optimal catalyst exhibits high H 2 O 2 yield of 451.8 µM, which is 3.8 times higher than the pristine g‐C 3 N 4 (119.0 µM) after 4 h and good stability after10 photocatalytic runs.