Formation of noble-metal-free 2D/2D ZnmIn2Sm+3 (m = 1, 2, 3)/MXene Schottky heterojunction as an efficient photocatalyst for hydrogen evolution

Ternary chalcogenides ZnmIn2S3+m (m = 1–3) has great potential in photocatalytic hydrogen evolution reaction if their low solar-to-hydrogen conversion efficiency and expensive co-catalyst assistance can be overcome. Herein, we adopt MXene (Ti3C2Tx) nanosheets as the noble-metal-free cocatalyst substrate to support the in situ growth of ultrathin ZnmIn2S3+m nanosheets, expediting charge separation and mobility, large surface area surface and hydrophilicity. Particularly, the Schottky junction formed at ZnmIn2S3+m/MXene interface induces the electrons transfer to MXene nanosheets timely and inhibits the backflow, further promote the separation of photogenerated charge carriers. This mechanism of the photocatalytic H2 evolution was further evidenced by the DFT calculations and experimental results. As a result, 2D/2D ZnmIn2S3+m/MXene exhibits good stability and an outstanding H2 yield under visible light irradiation, especially for Zn2In2S5/MXene (2.5 wt% of MXene), which is 2.67 times higher than that of pristine Zn2In2S5.