Enhancing photocatalytic H₂O₂ production with S-type heterojunctions of CeO₂ coupled N-vacancy-rich carbon nitride

Artificial photosynthesis for H₂O₂ production through O₂ reduction is a sustainable and cost-effective technology for the scientific and industrial communities. Metal-free polymeric carbon nitride (CN) is a promising visible-light responsive semiconductive material for photocatalytic H₂O₂ production. However, its inherently disordered and amorphous structure limits its performance improvement due to high photogenerated carrier complexation and sluggish interlayer charge transfer. Here, we report a high-performance S-type heterojunction, composed of CeO₂ coupled with N-vacancy-rich CN (CeO₂/Nv-CN), that enhances the photocatalysis of H₂O₂ production under visible light. The prepared CeO₂/Nv-CN showed an H₂O₂ generation rate of up to 69.79 mmol·g^-1·h^-1, 48.80-fold higher than CN and had an apparent quantum yield of 13.8 % at 400 nm. A synergistic effect among CeO₂, N-vacancies (Nv) and S-type heterojunction is responsible for such an excellent activity, which increased the O₂ and light absorption sites, built rapid charge diffusion channels, and enhanced two-electron O₂ reduction. This work demonstrates the potential of incorporating nanosized CeO₂ with CN to achieve high-performance photocatalytic H₂O₂ production, opening new avenues for designing highly efficient polymeric composite photocatalysts for energy conservation.