Enhancing photocatalytic activity of ZnO nanostructures by doping with Ce+4 ions prepared in water using ultrasonic irradiation

Abstract

Abstract Ultrasound was applied for preparation of ZnO nanostructures doped with different Ce/Zn ratios in water by irradiation for 60 min. In this method, zinc acetate, cerium sulfate and sodium hydroxide were used as starting materials without using any organic additives or post preparation treatments. Powder X-ray diffraction patterns indicate that the nanostructures are excellently crystallized in the form of wurtzite hexagonal phase. Scanning electron microscopy and transmission electron microscopy images show that the morphology of the nanostructures changes by doping with Ce+4 ions. The presence of the elements in the nanostructures was verified by energy dispersive X-ray spectroscopy. The UV–vis diffuse reflectance spectra of the nanostructures are similar to each other and they have a maximum at about 361 nm. The nanostructures with 0.025 mole fraction of Ce+4 ions exhibit the highest activity for degradation of methylene blue under UV irradiation. The reaction rate constant decreases with calcination temperature. Moreover, the rate constants in more acidic and alkaline solutions are lower than those of the neutral conditions. The photocatalyst retains 90 % of activity after being used four times.