Enhanced Gas-Sensing Response of Zinc Oxide Nanorods Synthesized via Hydrothermal Route for Nitrogen Dioxide Gas

In recent years, advanced material processing techniques have allowed scientists to research and document the properties of nanostructured metal oxides. One such material system, zinc oxide (ZnO), has emerged as a favorable option for a multitude of applications. In this study, thin films of ZnO with nanorod-like architectures were hydrothermally formed on a glass substrate and their physical and chemical properties were thoroughly characterized. X-ray diffraction confirmed the wurtzite structure and a scanning electron microscope was used to verify the vertical alignment of the rods. Defects due to the high oxygen vacancy concentration were revealed through photoluminescence studies. The high surface area of the nanorods works in conjunction with these defects and an optimal inter-rod spacing creates conditions for effective gas adsorption and diffusion. With this in mind, the nanorods were used to fabricate a gas sensor which demonstrated excellent NO2 sensitivity and selectivity at a relatively low operating temperature.