Functionalized Graphitic Carbon Nitrides for Photocatalytic H2O2 Production: Desired Properties Leading to Rational Catalyst Design

Photocatalytic H2O2 production based on graphitic carbon nitride (g-C3N4) materials has been attracting increasing attention. However, it is difficult to reveal the inner relationships among the structure, properties and performance of a g-C3N4-based photocatalyst by simply summarizing preparation methods, properties and performances in previous works. In this review, the three most important issues for improving H2O2 generation based on the band diagram and physicochemical properties of pristine g-C3N4 are proposed. Improvement of the charge separation, promotion of the light absorption and introduction of active sites for 2e− oxygen reduction reaction to suppress side reactions are the most three attractive strategies for enhancing the activities. Following discussion of these strategies, representative functionalization methods are summarized on the basis of the most desired properties for improving the photocatalytic activities for H2O2 production. Other influence factors for improving H2O2 production such as addition of electron donors and adjustment of pH value of the solution are also discussed. Future challenges for photocatalytic H2O2 based on g-C3N4 materials are also summarized to provide future directions in this field.