Insight into iron group transition metal phosphides (Fe2P, Co2P, Ni2P) for improving photocatalytic hydrogen generation

Iron group transition metal phosphides (TMPs, M= Fe, Co, Ni) have been considered as promising noble-metal-free cocatalysts for the photocatalytic hydrogen (H2) generation. However, the impact on the H2 generation activity in correlation with the types of metal in TMPs still remains unresolved. In this paper, to investigate the effect of metal phosphides with different metal on photocatalytic H2 generation, three types of iron group transition metal phosphides (M2P, M=Fe, Co, and Ni) nanoparticles were used as the cocatalysts of sulfur doped g-C3N4 (SCN) for the photocatalytic H2 generation. By comparing three types of M2P/SCN, the optimum cocatalyst of Ni2P has ca. 22.7 times that of the pristine SCN under the same condition. The photoluminescence (PL) spectra, photoelectrochemical characterization and DFT calculations confirmed the enhanced photo-induced charge transfer and band separation when SCN was integrated with the Ni2P.