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

Abstract

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.