Engineering nitrogen vacancies and cyano groups into C3N4 nanosheets for highly efficient photocatalytic H2O2 production

Thermal oxidation of bulky carbon nitride (C3N4, CN) to expose more active sites is an important method to improve the activity of the as-prepared CN nanosheets. Unfortunately, the yield of thermal oxidation is low. Herein, we report dual-deficient CN (DDCN) ultrathin nanosheets engineered with nitrogen vacancies and cyano groups by two-step bottom-up thermal polymerization of belt-like melamine with a high yield of 65 %. Featured with abundant exposed active sites, short charge migration distance, wide visible-light absorption, quick charge separation/transfer, enhanced oxygen adsorption ability and 2e oxygen reduction reaction selectivity, the DDCN exhibits a high H2O2 production rate of similar to 1031 mu mol g(1) h(1), which is 19.5 times that of CN (53 mu mol g(1) h(1)) under visible light irradiation (lambda >= 420 nm). Specifically, the apparent quantum yield (AQY) of DDCN reached 10.7 % at 420 nm. This study provides a facile dual-defect engineering method to develop highly efficient ultrathin CN-based photocatalysts.