Impact of Mg-doping on morphology, structure, optical properties, and enhancing photocatalytic performance of ZnO thin films, prepared by sol-gel spin-coated method

Abstract

Thin films of pure and Mg-doped ZnO (MZO) were successfully fabricated on glass substrates by solgel spin coating method. Microstructure, surface morphology, elemental composition, optical analysis, and Mg doping effect on the photocatalytic performance of the thin films have been measured by XRD, SEM, EDS, and UV-Vis, respectively. XRD analysis showed that ZnO and MZO thin films have a hexagonal wurtzite structure, and the intensity of the (002) peak moved from higher to lower angle and right to left with rising Mg-dopant concentration, and crystallinity was enhanced with doping, whereas micro strain and dislocation density dropped. SEM analysis found that ZnO had spherical and agglomerated structures, and the increased size of the grains was observed with increasing doping. The optical analysis demonstrated that the band gaps increased as the dopant percentage increased. Methylene blue, a dye pollutant, examined the thin films' photocatalytic performance. It was demonstrated that the addition of the Mg to the ZnO lattices increased the absorption of the hydroxyl ions at the surface of the thin film and hence acted as a trap site, leading to a decrease in the electron hole pair and consequently enhancing the photodegradation.