Persulfate-Induced Three Coordinate Nitrogen (N3C) Vacancies in Defective Carbon Nitride for Enhanced Photocatalytic H2O2 Evolution

In-situ photocatalytic H2O2 production has been receiving increasing attention in recent years for sustainable H2O2 synthesis. Graphitic carbon nitride (g-C3N4) is regarded as one of the most promising semiconductor photocatalysts for H2O2 evolution. Introducing N defects in g-C3N4 has been proved to be an effective strategy to enhance photocatalytic activity. However, the photocatalytic mechanism of the N vacancies is ambiguous and different types of N vacancies in g-C3N4 may exhibit different effects on photocatalytic activity. Herein, we develop a facile sodium persulfate eutectic polymerization method to prepare the g-C3N4 with abundant three coordinate nitrogen (N3C) vacancies. This type of nitrogen vacancy has not been studied in g-C3N4 for photocatalytic H2O2 production. Our results showed that the introduction of N3C vacancies in the g-C3N4 successfully broadened the light absorption range, inhibited the photoexcited charge recombination with enhanced O2 adsorption to promote oxygen activation. The photocatalytic H2O2 evolution from the N3C-rich g-C3N4 is 4.5 times higher than that of the pristine g-C3N4. This study demonstrates a novel strategy to introduce N3C vacancies in g-C3N4, which offers a new method to develop active catalysts for photocatalytic H2O2 evolution.