Metal‐Free Modification Overcomes the Photocatalytic Limitations of Graphitic Carbon Nitride: Efficient Production and In Situ Application of Hydrogen Peroxide

Abstract Graphitic carbon nitride (g‐C 3 N 4 ) assisted photocatalytic production of hydrogen peroxide (H 2 O 2 has already attracted the interest of many researchers due to its environmental sustainability. Nevertheless, the inherent drawbacks of g‐C 3 N 4 limit its progress. Metal‐free modification strategies, including nanostructure design, defect introduction, doping, and heterojunction construction, have been developed to improve the efficiency of g‐C 3 N 4 photocatalytic H 2 O 2 production. Compared to metal modification, metal‐free strategies avoid the use of precious metals and the leaching of heavy metal ions, which have the advantages of good stability and environmental friendliness. However, a comprehensive review of H 2 O 2 production from g‐C 3 N 4 modified by metal‐free strategies is still lacking. This review first recaps the mechanism of photocatalytic H 2 O 2 production by g‐C 3 N 4 , including photoexcitation, carrier separation and redox reactions. Then, the perspective advances in metal‐free modified g‐C 3 N 4 photocatalysts are presented, with the special focus on the kernel connection between different strategies and mechanism based on the pivotal stages of H 2 O 2 production. Subsequently, recent applications of g‐C 3 N 4 ‐based photocatalysts for in situ generated H 2 O 2 , mainly including water purification and organic synthesis, are briefly discussed. Finally, the prospects of g‐C 3 N 4 ‐based photocatalysts are envisioned with the hope that it will have “something to do” in the field of H 2 O 2 production.