Morphology-controllable synthesis and enhanced photocatalytic activity of ZnS nanoparticles

• Morphology-controlled ZnS were achieved by adjusting the Zn/S molar ratios.
• Size-related photocatalytic activity of ZnS micro/nanocrystallites was shown.
• Different kinds of dyes were used to test the photocatalytic activity of ZnS nanoparticles.
• The photocatalysis degradation reaction kinetics of MO was researched.

Well crystallized cubic sphalerite phase ZnS micro/nanocrystallites with controllable morphologies were successfully prepared by a facile and efficient microwave hydrothermal method. The syntheses were carried out by varying the Zn/S molar ratios. The phase compositions, morphologies and optical properties of the as-prepared samples were characterized by X-ray diffraction, scanning electron microscopy and UV–vis diffuse reflectance spectroscopy. Results show that with Zn/S molar ratio ranges from 2:1 to 1:2, the morphology of the prepared ZnS micro/nanocrystallites changed obviously. ZnS nanoparticles with good dispersibility prepared at Zn/S molar ratio of 1:2, which average size is about 20 nm, shows high photocatalytic activity to degrade Methyl orange (MO). The degradation efficiency of ZnS nanoparticles reaches 97.4% under UV irradiation for 20 min. The good ultraviolet absorbing ability and big specific surface area of ZnS nanoparticles are believed to have a positive impact on improving the final degradation rate and degradation efficiency of MO in our research.