Visible light photocatalytic synthesis of H2O2 on synergistic phosphorus-doped and defect engineered graphite C3N4

H2O2 is a green oxidant, which is widely used in chemical production, environmental remediation, sustainable energy conversion and the medical industry. The traditional anthraquinone method for producing H2O2 is facing issues, such as potential safety hazards and environmental pollution. Therefore, green and sustainable production of H2O2 is desirably investigated. Solar-driven photocatalytic synthesis of H2O2 is a promising method, which requires no additional energy input and will not produce new pollution. g-C3N4 is a kind of nonmetallic photocatalyst, which has the advantages of low cost, environmental friendliness and high stability. However, g-C3N4 still faces the problems of a narrow visible light response range, low photo-generated electron/hole separation efficiency and short carrier lifetime. The polymer properties of g-C3N4 are conducive to introducing foreign atoms into the main body of the tri-s-triazine structure. The electronic structure and optical properties of g-C3N4 can be adjusted by doping, which can significantly improve the photocatalytic performance of g-C3N4. In this work, phosphorus doped g-C3N4 (P/g-C3N4) is prepared by a simple chemical vapor deposition method. The doping process also introduced defects in the bulk phase of g-C3N4, which overcomes drawbacks such as weak visible light capturing ability, low charge separation and transfer efficiency, and a slow mass transfer rate. In addition, the optimized conduction band position further enhances the reduction ability of photo-generated electrons, making its photocatalytic performance magnify by one order of magnitude compared to that of pure g-C3N4. Driven by visible light, P/g-C3N4 produces H2O2 through the photocatalytic oxygen reduction reaction (ORR) in 2 h, reaching a high concentration of 1460.22 mu M, and it also maintains good catalytic repeatability in three-cycle catalytic experiments. P/g-C3N4 achieves the goal of efficient, stable and green synthesis of H2O2.