Study of iron group transition metal phosphides (M2P, M = Ni, Co, Fe) for boosting photocatalytic H2 production

The development and research of non-noble-metal cocatalyst is of great significance for efficient photocatalytic H2 production. Here, with iron group transition metal phosphides as cocatalyst, a series of noble-metal-free M2P/CdIn2S4 (M2P, M = Fe, Co, Ni) photocatalysts were severally prepared for photocatalytic hydrogen evolution. On the basis of the morphology and phase characterization, all M2P display the similar particle size and crystallization. The quadripartite synergistic modification of M2P in visible light absorption, carrier separation, H2-evolution kinetics and active site could significantly improve the photocatalytic activity of CdIn2S4. Under the same condition, for M2P/CdIn2S4 (M = Fe, Co, Ni), the maximal hydrogen production activity reached 316.8 μmol h−1 g−1, 471.9 μmol g−1 h−1 and 810.0 μmol g−1 h−1, which severally was 2.4, 3.6 and 6.2 times than CIS-Pt (130.5 μmol g−1 h−1). The results distinctly attest that, for CdIn2S4, M2P is an efficient co-catalyst for photocatalytic H2 production. Besides, Ni2P has the best co-catalytic activity for CdIn2S4. The best activity is attributed to the most efficient carrier separation resulting from the fact that Ni2P has the highest conductivity and the conduction band of Ni2P is closest to that of CdIn2S4. The work is beneficial to further exploit low-cost and high-efficient sulfides-based photocatalysts with iron group transition metal phosphides as cocatalysts for photocatalytic H2 production.