α-NiS–β-NiS growth on Cd0.5Zn0.5S formed Schottky heterojunctions for enhanced photocatalytic hydrogen production

Novel α-NiS–β-NiS nanosheet modified Cd0.5Zn0.5S nanoparticle heterojunctions have been successfully synthesized via a two-step solvothermal method. The α-NiS–β-NiS/Cd0.5Zn0.5S heterojunctions were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS) and UV-visible diffuse reflectance spectroscopy (UV-vis). The results reveal that the α-NiS–β-NiS/Cd0.5Zn0.5S heterojunctions have well-constructed integrated structures with strong adhesion between the Cd0.5Zn0.5S and α-NiS–β-NiS, which is beneficial to charge separation and transfer. The α-NiS–β-NiS/Cd0.5Zn0.5S heterojunctions demonstrated efficient photocatalytic hydrogen production and excellent stability, with hydrogen production reaching 3113 μmol g−1 h−1 for optimized structures which is approximately 2.9 times higher than that of pure Cd0.5Zn0.5S. More interestingly, the hydrogen production performance of NiS/Cd0.5Zn0.5S was influenced by the NiS crystal phase and the H2 generation rate of the α-NiS–β-NiS/Cd0.5Zn0.5S heterojunction is 1.3 times higher than that of β-NiS/Cd0.5Zn0.5S. According to the results of characterization and photocatalytic activity, the possible hydrogen evolution of mechanism for α-NiS–β-NiS/Cd0.5Zn0.5S was also proposed.