Sulfidization of Platinum Nickel Bimetal-Decorated g‑C₃N₄ for Photocatalytic Hydrogen Production: Photogenerated Charge Behavior Study

Seeking a high-efficiency and low-cost cocatalyst above graphite-like carbon nitride (g-C₃N₄) photocatalytic hydrogen evolution has been regarded as one of the most effective tactics to alleviate energy crisis. Herein, a novel S-PtNi_x/g-C₃N₄ photocatalyst is obtained with sulfidization of PtNi_x/g-C₃N₄ through hydrothermal synthesis. Impressively, the optimal photocatalytic property of 0.5S-PtNi_x/g-C₃N₄ is far and away higher than g-C₃N₄ and also is almost twice as high as PtNi_x/g-C₃N₄, achieving 4966 μmol h^–1 g^–1. This outstanding activity could be attributed to two factors. On the one hand, the modification of PtNi_x on g-C₃N₄ not only improves the separation efficiency but also accelerates the transfer of photogenerated charges. On the other hand, NiS_x could capture photogenerated electrons and work as a reactive site to participate in the photocatalytic reaction. In other words, the intensive activity of 0.5S-PtNi_x/g-C₃N₄ is ascribed to the synergistic effect of the charge transfer channel of PtNi_x and electron acceptor of NiS_x. This work for the first time illuminates the photocatalytic mechanism through the systematic characterization of photogenerated charges, which provides a theoretical basis for designing the photocatalyst modified with the cocatalyst upon photocatalytic hydrogen production.