The synergistic effect of P doping and Ni(II) electron cocatalyst boosting photocatalytic H2-evolution activity of g-C3N4

Abstract Doping heteroatoms and coupling cocatalysts are an effective way toward enhancing photocatalytic activity of semiconductor-based photocatalysts. Herein, Ni(II) modified P-doped g-C3N4 (NiPCN) was successfully prepared by an ion impregnation and phosphidation method. The Ni(II) as the electron cocatalyst and P-doping lead to 10 times of H2 evolution activity (1213 μmol h−1 g−1) compared with pristine g-C3N4 photocatalyst (117 μmol h−1 g−1). Detailed experimental results together with theoretical study revealed that the P-doping and Ni(II) as an electron cocatalyst can speed up electron transfer, leading to an enhancement of photocatalytic activity. The ultrafast transient absorption spectroscopy results disclosed that the synergistic effect of Ni(II) as an electron cocatalyst and P doping helps to increase the carrier's lifetime, resulting in the efficient electron transfer and long-lived charge separation. It is believed that this work opens up a possible way for optimizing the separation of photoexcited carriers for photocatalytic H2-evolution. (~1761 ps) is much slower than that (τ2) of the CN (576 ps)