Simple hydrothermal synthesis of g-C3N4/Ni9S8 composites for efficient photocatalytic H2 evolution

The prompt recombination between photogenerated electrons and holes is the common problem for improving the hydrogen evolution performance of a photocatalyst, which could be solved greatly by composite co-catalysis. Herein, a simple hydrothermal reaction was utilized to prepare g-C3N4/Ni9S8 composite photocatalysts. Through electroless nickel plating, Ni9S8 nanostructure was homogeneously grown onto the g-C3N4 surface by using sodium hypophosphite as reducing agent. With the optimum loading amount of Ni9S8, the acquired composite, compared with the raw g-C3N4, presented a significant increase in hydrogen evolution rate under visible light irradiation, which was measured as 355.7 μmol g−1 h−1 at 7 °C, being 21.2 times that of raw g-C3N4. The mechanism for the hydrogen evolution reaction over the present g-C3N4/Ni9S8 composite photocatalysts was discussed in detail.