The Na-doped g-C3N4/Ni-MOF composite efficiently generates hydrogen peroxide using atmospheric oxygen for the treatment of water pollutants

Hydrogen peroxide (H₂O₂) is a green oxidant with increasing demand in environmental remediation and energy-related applications. Photocatalytic H₂O₂ production using graphitic carbon nitride (g-C₃N₄) offers a sustainable and eco-friendly alternative to conventional synthesis methods. However, the effect of pure g-C₃N₄ modification on its photocatalytic surface properties requires further investigation. In this study, nickel-based metal-organic framework/Na-doped g-C₃N₄ (Ni-MOF/Na-CN) S-scheme heterojunction photocatalyst was designed and synthesized to overcome the limitations of conventional g-C₃N₄-based systems for photocatalytic H₂O₂ production. Under ambient air conditions, the optimized Ni-MOF/Na-CN-4 achieved an H₂O₂ generation rate of 1230.8 μmol/g/h, surpassing most reported systems. Na⁺ doping effectively modulated the band structure of g-C₃N₄, while the Ni-MOF component provided abundant active sites and enhanced O₂ adsorption and activation. The formation of the S-scheme heterojunction further promoted efficient separation of photogenerated electrons and holes. Moreover, hydrogel microspheres prepared from Ni-MOF/Na-CN-4 (Ni-MOF/Na-CN-4@MS) exhibited excellent performance in water pollutant remediation, achieving 99 % methylene blue (MB) degradation within 1 h and effectively inactivating Escherichia coli (E. coli) via H₂O₂-induced membrane damage. This work provides valuable insights for the development of highly efficient and sustainable photocatalysts for H₂O₂ production and water pollutant remediation.