Flower-like ZnIn2S4 microspheres with highly efficient catalytic activity for visible-light-driven sulfamethoxazole photodegradation

Photocatalysis using ZnIn2S4 (ZIS) is demonstrated as a highly efficient zero carbon emission technology using solar energy as the only energy input. In this study, flower-like ZIS microspheres in perfect shape has been successfully prepared by a facile hydrothermal route for the effective degradation of sulfamethoxazole (SMX) in the visible light irradiation. The microsphere exhibits a better spherical shape with uniform particle size of 4–5 µm and large petals of ~10 nm thickness. The initial effect of ZIS nanostructure adjustment is by changing the pH value in the hydrothermal process. The experimental results showed that the flower-like ZIS microspheres synthesised via hydrothermal treatment at pH 1.0 over 16 h at 160 °C have a degradation efficiency of over 90% SMX. The reason is ascribed to more efficient charge separation replying on the specific nanostructure with a large interface contact area of ZIS. In addition, the optimally initial pH in sulfamethoxazole (SMX) degradation system at the highest photocatalytic efficiency is 5.0 approximately. The dominant radical species, namely O2•−, is demonstrated by using electron paramagnetic resonance technology. This study provides a facile synthesis method for the preparation of highly efficient visible light photocatalysts.