Synthesis, characterization, and photocatalytic application of silver doped zinc oxide nanoparticles

Abstract

The advancement in nanotechnology has influenced the improvement in the photocatalytic performance of zinc oxide nanoparticles (ZnO NPs). The photocatalytic activities of ZnO are within irradiation wavelengths in the ultraviolet region and this hinders its efficiency in photocatalytic applications. Undoped and silver doped ZnO nanoparticles (Ag-doped ZnO NPs) were successfully prepared by co-precipitation technique at Ag doping concentrations of 0, 0.25, 0.5, 0.75, and 1 % to enhance the photocatalytic ability of ZnO NPs. The XRD results indicate a hexagonal wurtzite structure of the undoped and Ag-doped ZnO NPs with the estimated crystalline size ranges from 30.79, 23.72, 36.97, 21.49, and 25.66 nm, respectively, for ZnO at Ag doping concentrations. The SEM micrograph revealed the uniform distribution of Ag on the surface of ZnO NPs and a decrease in the size of the particle as concentration increases. The displacement in the absorption edge of ZnO to a higher wavelength led to narrowing the optical bandgap of ZnO due to Ag doping, as observed in the DRS spectra. Photocatalytic performance and photodegradation experiments were conducted using a model methylene blue (MB) dye contaminated in water. The dye concentration decreases as irradiation time increases in the presence of the photocatalyst with the improved performance of less exposure time and the highest dye degradation of about 98 %. It was revealed that the photocatalytic activity of ZnO toward MB degradation was effectively improved by Ag doping. Therefore, Ag doping of ZnO NPs had the synergetic effect of enhancing the photocatalytic activity of ZnO NPs.

Keywords

• Silver
• Zinc oxide nanoparticles
• Doping
• Co-precipitation
• Photocatalysis
• Bandgap