Enhancing Photocatalytic Activity of Graphitic Carbon Nitride by Codoping with P and C for Efficient Hydrogen Generation

The generation of clean hydrogen gas from photocatalytic water splitting by using graphitic carbon nitride (g-C3N4) as the photocatalyst has attracted considerable research interest. For practical applications, however, the photocatalytic activity of g-C3N4 needs to be further improved by, for example, band gap engineering through heteroatom doping. In this study, we found that doping of carbon nitride with carbon and phosphorus (P) could tune energy level of the conduction band. Subsequent hydrothermal treatment led to an increase in the specific surface area from 24.9 up to 141.1 m2 g–1, which was accompanied by increasing C concentration of the resultant C, P-doped g-C3N4 to reduce the hole–electron recombination and enhance the conductivity. Consequently, the C, P-codoped g-C3N4 (i.e., CPCN-1*) exhibited a much enhanced photocatalytic activity for efficient generation of H2 by photocatalytic water splitting under visible-light irradiation (1493.3 μmol g–1 h–1—about 9.7 times enhancement from that of bulk g-C3N4).