Single-electron effects regulate the electronic structure of carbon nitride to enhance photocatalytic hydrogen peroxide generation and pollutant degradation performance

Photocatalysis technology can convert H₂O and O₂ into H₂O₂ by using solar energy; however, the efficiency of photocatalytic H₂O₂ production is limited by the high electron-hole recombination rate, poor oxygen reduction ability, and weak O₂ adsorption capacity. Herein, we construct a phosphorus (P)-doped graphitic carbon nitride (g-C₃N₄, i.e., CN) photocatalyst, denoted as P-CN, by adjusting the bandgap and electronic structure of CN to improve its charge distribution, increase its separation efficiency for photogenerated carriers, and enhance its oxygen reduction ability. In addition, P doping forms two lone pairs of electrons on the CN surface, considerably enhancing the adsorption and activation of O₂, thereby synergistically facilitating the photocatalytic production of H₂O₂. Results demonstrate that the H₂O₂ yield of 7.5 % P-CN can reach 719.68 µmol·L^-1, which is 2.2 times that of CN. Considering the reaction pathway, intermediate structure of H₂O₂ production, and density functional theory (DFT) results, the mechanism of the single electron effects to improve O₂ adsorption as well as H₂O₂ yield was proposed. In addition, the single-electron effect caused by P doping facilitates both the degradation activity of CN and efficiency there for hydrogen production, which provides new ideas for designing and regulating the electronic structure of catalysts and improving their reaction performance.