Enhanced nonsacrificial photocatalytic generation of hydrogen peroxide under visible light using modified graphitic...

The photocatalytic production of H₂O₂ by graphite-phase carbon nitride (g-C₃N₄) using water and oxygen is a promising and sustainable method. Nevertheless, the yield of H₂O₂ produced by the pristine g-C₃N₄ is still far from satisfactory owing to limited optical absorption, rapid photogenerated electron-hole recombination and poor surface electron migration. Therefore, p-P₁CN/CQDs₂₅ was designed and synthesized by doping phosphorus (P) and loading carbon quantum dots (CQDs) to modify porous g-C₃N₄ (p-CN) via a facile method. Herein, P acted as an electron transfer bridge to induce electrons into CQDs, while CQDs acted as an electron trapping material to capture and stabilize photogenerated electrons. Moreover, CQDs could enhance their optical absorption due to its unique optical properties. Notably, p-P₁CN/CQDs₂₅ presented highly boosted H₂O₂ generation activity, its H₂O₂ production yield for 5 h was up to 494 μM/L and the formation rate constant K_f in the first hour was 238 μM h^-1 without adding sacrificial agents and without bubbling oxygen under visible light, which took precedence among the reported results under the same conditions. It should be noted that the composite p-P₁CN/CQDs₂₅ also possessed low H₂O₂ decomposition behavior based on the effect of CQDs stabilizing electrons. In addition, the possible mechanism of photocatalytic H₂O₂ generation for p-P₁CN/CQDs₂₅ was also proposed. Our research provided a new idea for the design of novel photocatalysts to efficient generation of H₂O₂.