Synthesis of layer-like Ni(OH)2 decorated ZnIn2S4 sub-microspheres with enhanced visible-light photocatalytic hydrogen production activity.

Novel layer-like Ni(OH)2 co-catalyst-decorated ZnIn2S4 microsphere photocatalysts were synthesized for the first time via a facile in situ deposition method to boost the photocatalytic H2-production performance. The physical and optical properties of the as-prepared Ni(OH)2-ZnIn2S4 composite samples were characterized via X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-vis diffusion reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS), and surface photovoltage spectroscopy (SPV). The results indicate that the photocatalytic H2 evolution activity of the ZnIn2S4 microspheres under visible light irradiation significantly enhances by introducing inexpensive Ni(OH)2 as a co-catalyst. The 5 mol% Ni(OH)2-ZnIn2S4 sample shows the highest H2-production rate of 8.35 mmol g-1 h-1, which is 18 times higher than that of pure ZnIn2S4. Moreover, photocatalytic activity of the Ni(OH)2-ZnIn2S4 sample remains stable even after 4 cycling photocatalytic experiments. In addition, a possible mechanism on the enhanced photocatalytic activity was proposed and verified by surface photovoltage spectroscopy.