Morphology-dependent structural and optical properties of ZnO nanostructures

Zinc oxide nanostructures with three different morphologies, namely, nanoparticles (NP), nanorods (NR) and nanosheets (NS) were synthesized using chemical co-precipitation method. X-ray diffraction patterns showed that all the ZnO nanostructures had hexagonal wurtzite structures. The average crystallite size of NP, NS, and NR was found to be 25, 27 and 35 nm, respectively. The morphology and size of nanostructures were confirmed by scanning electron microscopy and transmission electron microscopy. The optical properties of zinc oxide nanostructures were investigated using UV–Vis absorption spectroscopy and photoluminescence (PL) spectroscopy. The optical band gap was found to be 3.26, 3.24 and 3.10 eV for NP, NS, and NR nanostructures, respectively. It was clearly observed from the PL spectrums that luminescence intensity was maximum for NP in the UV region and maximum for NS in the visible region. It is evident from the results that by changing the size and morphology of ZnO nanostructures, the optical properties can be tuned according to their desired applications.