High efficient photocatalytic selective oxidation of benzyl alcohol to benzaldehyde by solvothermal-synthesized ZnIn_2S_4 microspheres under visible light irradiation

摘要

Hexagonal ZnIn_2S_4 samples have been synthesized by a solvothermal method. Their properties have been determined by X-ray diffraction, ultraviolet-visible-light diffuse reflectance spectra, field emission scanning electron microscopy, nitrogen adsorption-desorption and X-ray photoelectron spectra. These results demonstrate that ethanol solvent has significant influence on the morphology, optical and electronic nature for such marigold-like ZnIn_2S_4 microspheres. The visible light photocatalytic activities of the ZnIn_2S_4 have been evaluated by selective oxidation of benzyl alcohol to benzaldehyde using molecular oxygen as oxidant. The results show that 100% conversion along with > 99% selectivity are reached over ZnIn_2S_4 prepared in ethanol solvent under visible light irradiation (2>420 nm) of 2 h, but only 58% conversion and 57% yield are reached over ZnIn_2S_4 prepared in aqueous solvent. A possible mechanism of the high photocatalytic activity for selective oxidation of benzyl alcohol over ZnIn_2S _4 is proposed and discussed.