Sonochemical synthesis of Ga-doped ZnS nanoballs with enhanced photocatalytic activity for Orange II dye degradation in wastewater

Abstract

In this study, different molar amounts (0-3.0 mol%) of gallium ions doped onto the lattice of ZnS nanoballs were synthesised by sonochemical irradiation approach without using any template. From the results, we could find that the gallium-doped ZnS particles are held together and assembled into irregular spherical shapes, which were arranged in the form of clusters, with 50-200 nm sizes. The peak positions of Zn2p and S2p of the 3.0 Ga/ZnS nanoballs shifted slightly towards lower binding energy compared to the pristine ZnS. The emission intensity of photoluminescence was enhanced with the increasing doping gallium concentration due to the crystal quality with higher defects. Gallium-doped ZnS nanoballs had a sufficient over-potential of CB and VB to improve the degradation efficiency of Orange II dye. Upon performing photocatalytic degradation of Orange II dye under UV light irradiation, the highest first-order rate constant (0.0143 min-1) was obtained for 1.0 Ga/ZnS nanoballs. In addition, the degradation mechanism is discussed in detail.