Photocatalytic hydrogen generation over porous ZnIn2S4 microspheres synthesized via a CPBr-assisted hydrothermal method

Graphical abstract: ZnIn2S4 porous microspheres were synthesized via a cetylpyridinium bromide (CPBr)-assisted hydrothermal method. It could be seen from the SEM image that the flowerlike microspheres were composed of numerous nanosheets. Many slit-like pores were formed among the curved nanosheets. The porous structure benefited the adsorption of reactants, the diffuseness of products, the charge separation on surface, the transfer of the interfacial charge carriers and the charge carrier trapping. And porous ZnIn2S4 photocatalyst exhibited higher photocatalytic activity than nonporous ZnIn2S4 material. Highlights: → A series of unique flower-like porous ZnIn2S4 microspheres of hexagonal crystal phase as efficient visible-light photocatalysts have been synthesized through CPBr-assisted hydrothermal method. → The CPBr addition would visibly influence the self-assemble growing and the crystal structure including the position and intensity of some peaks. → We also found that the pH value plays a crucial role in the formation of ZnIn2S4 porous microspheres and the influence of the pH on the structure of product has been first reported in our paper. → The results showed that our as-synthesized porous ZnIn2S4 microspheres possessed a specific surface area of 165.4 m2 g-1 and performed higher visible-light photocatalytic activity than bulk ZnIn2S4 for hydrogen evolution. The maximum H2 evolution rate of ZnIn2S4 reaches 1544.8 μmol/(h g). -- Abstract: Hexagonal ZnIn2S4 porous microspheres were synthesized via a cetylpyridinium bromide (CPBr)-assisted hydrothermal method. The structure, morphology and optical property of these prepared products were characterized by wide angle X-ray diffraction (WAXRD), small angle X-ray diffraction (SAXRD), UV-Vis diffusive reflectance spectroscopy (DRS), field emission scanning electron microscopy (FESEM), energy dispersive X-ray analyzer (EDX) and nitrogen sorption analysis. The effects of CPBr and pH on the crystal structure, morphology and photocatalytic activity of ZnIn2S4 products were studied. The results demonstrated that the flowerlike ZnIn2S4 microspheres, which were composed of numerous nanosheets, performed higher visible-light photocatalytic activity than bulk ZnIn2S4 for hydrogen evolution. The CPBr addition influenced the crystal structure including the position and intensity of some peaks. Furthermore, the pH played a crucial role in the formation of ZnIn2S4 porous microspheres. The as-synthesized porous ZnIn2S4 microspheres possessed the specific surface area of 165.4 m2 g-1 and the slit-like porous configuration, which was beneficial to photocatalytic reaction.