Multiscale structural engineering of carbon nitride for enhanced photocatalytic H2O2 production

Carbon nitride (C3N4) holds great promise for photocatalytic H2O2 production from oxygen reduction. In spite of great research efforts, they still suffer from low catalytic efficiency primarily limited by the fast recombination of photogenerated charge carriers. In this work, we report the multiscale structural engineering of C3N4 to significantly improve its optoelectronic properties and consequently photocatalytic performance. The product consists of porous spheres with high surface areas, abundant nitrogen defects, and alkali metal doping. Under visible light irradiation, our catalyst shows a remarkable H2O2 production rate of 3,080 µmol·g−1·h−1, which is more than 10 times higher than that of bulk C3N4 and exceeds those of most other C3N4-based photocatalysts. Moreover, the catalyst exhibits great stability, and can continuously work for 15 h without obvious activity decay under visible light irradiation, eventually giving rise to a high H2O2 concentration of ca. 45 mM.