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 (H-2) generation. However, the impact on the H-2 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 H-2 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 (S-CN) for the photocatalytic H-2 generation. By comparing three types of M2P/S-CN, the optimum cocatalyst of Ni2P has ca. 22.7 times that of the pristine S-CN under the same condition. The photoluminescence (PL) spectra, photoelectrochemical characterization and DFT calculations confirmed the enhanced photo-induced charge transfer and band separation when S-CN was integrated with the Ni2P.