Enhanced Carrier Separation and Band Structure Regulation of Nitrogen-Doped ZnIn₂S₄ for Photocatalytic Hydrogen Peroxide Production

Hydrogen peroxide (H2O2) has a wide range of applications in the chemical, medical, wastewater treatment, and fuel cell industries, but its current main production process is energy-intensive and generates a large number of toxic byproducts. In contrast, the production of H2O2 by a photocatalytic oxygen reduction reaction (ORR) or water oxidation reaction (WOR) using renewable solar energy, air, and water is one of the most promising technologies available. Herein, nonmetallic nitrogen-doped ZnIn2S4 (ZIS) was prepared by a simple solvothermal method by adding N,N-dimethylformamide as a nitrogen source into the ZIS precursor solution. The doping of nitrogen effectively suppressed the complexation of the photogenerated carriers, which allowed more photogenerated electrons to participate in the ORR. In addition, the nitrogen doping modulated the energy band structure of ZIS, and the negative shift of the conduction improved the reduction ability of photogenerated electrons as well as the photostability of the material. The results show that the optimized nitrogen-doped ZIS material can produce H2O2 by two-step single-electron indirect ORR without the use of sacrificial reagents, and the yield of H2O2 is 0.7 mmol g–1 h–1, which is significantly higher than that of the pristine ZIS.