Fabrication of novel noble-metal-free ZnIn2S4/WC Schottky junction heterojunction photocatalyst: Efficient charge separation, increased active sites and low hydrogen production overpotential for boosting visible-light H2 evolution

Herein, we report the synthesis of ZnIn2S4 nanoparticles on bulk WC by a facile hydrothermal process to construct novel and highly efficient noble metal-free Schottky junction heterojunction photocatalysts. Morphology characterization revealed that the ZnIn2S4 nanoparticles were deposited on the surface of the WC. Meanwhile, the combination of the ZnIn2S4 and the metal-like WC formed the Schottky energy barrier, which greatly promoted the migration and separation of photo-generated carriers. Especially, the optimal ZnIn2S4/WC photocatalysts have a lower overpotential for hydrogen evolution (−0.35 V) than pristine ZnIn2S4 (−0.49 V). The hydrogen production ability of the optimal ZnIn2S4/WC photocatalyst (2400.3 μmol·h−1·g−1) was approximately 9.2 times higher than that of ZnIn2S4-1% Pt (260.1 μmol·h−1·g−1). Photocatalytic experiments demonstrated that metal-like WC plays an important role in replacing precious metal to increase the active site of ZnIn2S4. Moreover, a feasible Schottky junction reaction mechanism of intensive photocatalytic activity was discussed. This study proves that it is a very fascinating strategy to combine the advantages of ZnIn2S4 and metal-like to construct Schottky heterojunction for photocatalytic hydrogen production.