Effect of Au nanoparticles doping on the structure, surface morphology and optical properties of ZnAgO Nanorods

In this work, nanoparticles (NPs) composed of noble elements (Au and Ag) were prepared using a chemical reduction method and then combined with a spray pyrolysis technique for synthesizing ZnAgO and Au-doped ZnAgO nanorods (NRs). The films were produced by adding 2 wt% of Ag NPs and 2, 4, and 6 wt% of Au NPs at 420°C. The results showed that the films have a polycrystalline ZnO (wurtzite) with a hexagonal structure. Also, all films had a preference orientation along the (002) plane. The crystal size increased with increasing Au doping from 64.4 to 65.33 nm. For ZnO doped with Ag NPs, a uniform distribution of NPs on the substrate surface with little porosity was observed. After adding Au NPs, there is a variety in the diameter and porosity of the prepared nanorod samples. The diameters range decreased from (180-200) nm for the ZnAgO to (80-120) nm after 2 wt% Au doping and then rose to (190-200) nm and (160-220) nm with 4 wt% and 6 wt% Au doping, respectively. With doping Au at different ratios, the films showed an intense absorbance in the UV extent and great transmittance in the visible area. The optical energy band gap of ZnAgₓO increased from 3.25 eV to 3.35 and 3.32 eV with Au doping of 2 and 4 wt%, respectively, and decreased after adding 6 wt% of Au NPs to 3.26 eV. According to the obtained findings, Au and Ag doping substantially impacted the optical performance of ZnO film