Efficient visible-light activation of molecular oxygen to produce hydrogen peroxide using P doped g-C3N4 hollow spheres

Abstract

Graphitic carbon nitride (g-C₃N₄) possesses unique electronic and optical properties in the visible-light-driven production of H₂O₂. However, bulk g-C₃N₄ suffers from inefficient sunlight absorption and low carrier mobility. Herein, P doped g-C₃N₄ with a hollow sphere architecture was synthesized. The hollow sphere structure provides a large accessible surface area for charge transfer and enhances photo-absorption properties. Particularly, the doped P can regulate the energy band structure with stronger reducibility for O₂ activation and accelerate photo-generated carrier separation. Meanwhile, the P heteroatom is beneficial to produce 1,4-endoperoxide species more easily and enhance selectivity for H₂O₂ synthesis through a two-electron O₂ reduction process. The resultant catalyst exhibits a high H₂O₂ production rate of 174 μmol h⁻¹ g⁻¹ in pure water and 1684 μmol h⁻¹ g⁻¹ with isopropanol as a hole scavenger, which are 7.5 and 11.2 times those of bulk g-C₃N₄. This work provides a new avenue for the design and modification of other photocatalysts for H₂O₂ production.