Strategic nitrogen defect engineering for optimizing the photocatalytic performance of polymerized carbon nitride: Identification, synthesis, and mechanism

Although graphitic carbon nitride (g-C3N4) is frequently mentioned as an environmentally friendly and low-cost photocatalyst, its photocatalytic efficiency is severely constrained by its greater band gap and easy recombination of photogenerated carriers. Introducing nitrogen defects into the photocatalyst can effectively improve the photocatalytic efficiency of g-C3N4. As the position and concentration of inserted nitrogen defects are important factors affecting the catalytic performance of g-C3N4, this review summarized the synthesis methods developed in recent years based on the perspective of the regulation of nitrogen defect position and concentration. Additionally, this study provided an overview of the characterization methods for discovering nitrogen defects and accurately identifying their exact positions in g-C3N4. At the same time, the mechanism of nitrogen defects promoting the photocatalytic performance of g-C3N4 was explored from aspects such as enhancing light absorption, promoting the transfer and separation of photogenerated carriers, and increasing the consumption of photogenerated carriers through surface reactions. Finally, the opportunities and challenges of nitrogen defects in identification, synthesis, and mechanism of action were discussed.