Near Infrared Light-Driven Photoelectrocatalytic Water Splitting over P-Doped g-C₃N₄

Because infrared (IR) light accounts for almost 50% of solar light, exploring IR-response materials for the photoelectrochemical water-splitting process is of great interest. In this work, phosphorus (P)-doped g-C3N4, which was successfully synthesized using a simple sintering method, exhibited an IR light response with 1.4 μA/cm2 of current at 1.2 V versus Ag/AgCl under near IR light (>800 nm) irradiation. 1.27 μmol h–1 g–1 of hydrogen was produced with P/g-C3N4 as a photoanode at 0.6 V versus Ag/AgCl, while a negligible amount of H2 was detected with a g-C3N4 photoanode. This happened because the introduction of P into g-C3N4 narrowed its band gap from 2.75 to 1.37 eV, leading to a superior IR light response. Furthermore, the P-doping also remarkably improved the charge separation and transfer in g-C3N4.