2D β-NiS as electron harvester anchors on 2D ZnIn2S4 for boosting photocatalytic hydrogen production

Abstract

Promoting charge separation and surface redox reactions are crucial to improving hydrogen production by semiconductor photocatalysis. Therefore, photocatalysts comprised of light absorbers and cocatalysts with intimate interfaces have received extensive attention. Herein, a novel β-NiS nanosheets modified ultra-thin ZnIn2S4 nanosheets heterojunction is successfully synthesized via a simple two-step method. The physical and photophysical properties of NiS/ZnIn2S4 heterojunction were characterized by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and UV–visible diffuse reflectance spectroscopy (UV–vis). The results reveal that the obtained 2D/2D NiS/ZnIn2S4 heterojunction has a well-constructed integrated structure of strong adhesion between the ZnIn2S4 nanosheets and the cocatalyst NiS nanosheets, which is beneficial to charge transfer and light absorption. Consequently, the NiS/ZnIn2S4 heterojunction presents extraordinarily highly efficient photocatalytic hydrogen production, and excellent stability. The hydrogen production of the optimal NiS/ZnIn2S4 reaches to 13.57 mmol g−1 h−1, to be approximately 10 times that of pure ZnIn2S4 nanosheets. More importantly, the H2 generation rate of the 2D/2D NiS/ZnIn2S4 heterojunction is higher than that of Pt/ZnIn2S4. According to the results of characterization and photocatalytic activity, a possible mechanism of charge transfer is also proposed.