Enhanced Photocatalytic H2O2 Production over Carbon Nitride by Doping and Defect Engineering

Photocatalytic production of H2O2 from the reduction of O-2 by semiconductor photocatalysts (e.g., graphitic carbon nitride, C3N4) has been regarded as an alternative for small-scale decentralized H2O2 production. However, the efficiency of pristine C3N4 photocatalysts is still limited by the narrow light absorption range and rapid charge recombination. Here, we presented a facile approach to simultaneously enhance the light absorption and promote the charge separation by introducing alkali metal dopants and N vacancies on C3N4. The introduction of alkali metal dopants and N vacancies successfully broadened the light absorption range, reduced the band gap from 2.85 to 2.63 eV, and greatly inhibited the charge recombination. The synergistic effect of doping and defect resulted in the improvement of photocatalytic performance with a H2O2 production rate of 10.2 mmol/h/g, which is 89.5 times that of pristine C3N4. Thus, this work not only gives insights into the synergistic effect of doping and defect for simultaneously manipulating the light absorption and charge separation processes but also inspires further work to develop more efficient photocatalysts for H2O2 production.