Ultrasonic-assisted Method for Preparation of Cu-doped ZnS Nanoparticles in Water as a Highly Efficient Visible Light Photocatalyst

Ultrasonic-assisted method was applied for preparation of Cu+2-doped ZnS nanoparticles (mole fractions of Cu+2 ions are 0.000, 0.015, 0.030 and 0.060) in water as a template-free and green method at 30 min. The prepared nanoparticles were investigated by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) and UV–Vis diffuse reflectance spectra (DRS) techniques. In the prepared nanoparticles, Cu+2 ions are incorporated into the ZnS lattice. The nanoparticles have absorption edges at visible light region. The SEM images demonstrate that size of the nanoparticles decreases with Cu+2 content. To achieve maximum degradation efficiency, the influence of various operational parameters such as mole fraction of Cu+2 ions, ultrasonic irradiation time, catalyst weight, calcination temperature, concentration of methylene blue (MB) and pH of solution on the degradation rate constant was investigated under visible light irradiation and the results discussed. It was found that the degradation reaction followed pseudo first-order kinetics. The nanoparticles with 0.015 mole fraction of Cu+2 ions exhibit highest activity among the prepared samples.