Phosphorus-Doped Hollow Tubular g-C₃N₄ for Enhanced Photocatalytic CO₂ Reduction

Photocatalytic CO₂ reduction is a tactic for solving the environmental pollution caused by greenhouse gases. Herein, NH₄H₂PO₄ was added as a phosphorus source in the process of the hydrothermal treatment of melamine for the first time, and phosphorus-doped hollow tubular g-C₃N₄ (x-P-HCN) was fabricated and used for photocatalytic CO₂ reduction. Here, 1.0-P-HCN exhibited the largest CO production rate of 9.00 μmol·g^-1·h^-1, which was 10.22 times higher than that of bulk g-C₃N₄. After doping with phosphorus, the light absorption range, the CO₂ adsorption capacity, and the specific surface area of the 1.0-P-HCN sample were greatly improved. In addition, the separation of photogenerated electron-hole pairs was enhanced. Furthermore, the phosphorus-doped g-C₃N₄ effectively activated the CO₂ adsorbed on the surface of phosphorus-doped g-C₃N₄ photocatalysts, which greatly enhanced the CO production rate of photocatalytic CO₂ reduction over that of g-C₃N₄.