Recent Progress in g-C3N4-Based Photocatalysts for Organic Pollutant Degradation: Strategies to Improve Photocatalytic Activity

With unique photochemical properties, graphitic carbon nitride (g-C3N4) has gained significant attention for application in photocatalytic degradation of a wide range of organic pollutants. However, its performance is limited by the rapid electron–hole recombination and the relatively weak redox capability. Substantial progress has been made in the preparation of g-C3N4-based photocatalysts with enhanced photocatalytic activity. This review summarizes the recent advances in strategies to improve the photocatalytic activity of g-C3N4-based photocatalysts and their application in the photocatalytic degradation of organic pollutants. Morphology control, doping, functionalization, metal deposition, dye sensitization, defect engineering, and construction of heterojunctions can be used to improve the photocatalytic activity of g-C3N4 through promoting charge carrier separation, reducing the bandgap, and suppressing charge recombination. Furthermore, a range of oxidants, such as hydrogen peroxide and persulfate, can be coupled with g-C3N4-based photocatalysts to enhance the generation of reactive oxygen species and boost the photocatalytic degradation of organic pollutants. Precise control over the g-C3N4 structure during the synthesis process remains a challenge, and further improvements are required in photocatalyst stability and the mineralization rates of organic pollutants. More research and development effort is needed to address the existing challenges, refine the design of g-C3N4-based photocatalysts to improve their activity, and promote their practical application in pollutant degradation.