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 mu mol<middle dot>g(-1)<middle dot>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.