Synthesis and characterization of chemically deposited ZnO nanorods for NO2 gas sensing applications

Zinc oxide (ZnO) nanorod arrays were deposited on to the soda-lime glass substrates by wet chemical route using zinc acetate as precursor. The structural and surface morphological properties of the ZnO nanorod arrays (ZNAs) were investigated by X-ray diffraction (XRD), and scanning electron microscopy (SEM) respectively. The XRD pattern revealed wurtzite crystal structures of ZNAs, preferentially orienting in the (002) direction. Depending on the length of nanorod, the intensity of the (002) plane was found to be varied. SEM micrographs show the vertical alignment of ZNAs perpendicular to the substrate and increase in rod length with increase in deposition time. The Gas sensing device was prepared by using ZNAs and tested for NO₂ gas at different temperatures, concentrations and size of nanorods. Response increased with gas concentration as well as temperature. It was revealed that ZNAs gas sensor operating at 150 ⁰C temperature could detect NO₂ at low concentration (100ppm) with very high sensitivity (90 %).