Enhanced nonsacrificial photocatalytic generation of hydrogen peroxide under visible light using modified graphitic carbon nitride with doped phosphorus and loaded carbon quantum dots: Constructing electron transfer channel

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 Kf 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.