Bulk ZnO, nanoparticles, nanorods and thin film: A comparative study of structural, optical and photocatalytic properties

Abstract

Zinc oxide (ZnO) nanostructures, including nanoparticles, nanorods, and thin film, were prepared using thermal decomposition, hydrothermal and sputtering methods, respectively. Structural and optical properties of the nanostructures were compared with bulk ZnO. X-ray diffraction patterns of the samples show the formation of the wurtzite structure. XRD pattern demonstrates that the nanorods have grown along the [002] direction. Particle size obtained by FESEM shows that the nanoparticles, nanorods, and thin film, with different grain size were prepared. Atomic force microscopy (AFM) images of the thin film confirmed the uniformity of the ZnO layer, and a more significant peak-to-valley height than the thickness of the sputtered zinc layer (300 nm) was obtained. Band gap of the bulk sample was higher than the nanostructures, which was due to fewer defects in the bulk sample. Photoluminescence spectrum confirmed the presence of defects and emissions due to near absorption edge in the nanostructures and bulk sample. Finally, the photocatalytic activity of the samples was evaluated for degradation of oxytetracycline antibiotic. The high degradation rate of nanoparticles was attributed to the high surface/volume ratio and inherent defects. With the high photocatalytic efficiency, the prepared ZnO nanoparticles sample can be considered as potential candidate for water treatment and removal of environmental pollutants.