Synthesis of 1D Sn-doped ZnO hierarchical nanorods with enhanced gas sensing characteristics

Abstract

Pure and Sn-doped hierarchical ZnO based 1D single-crystalline nanorods were produced by chemical vapour transport and condensation process in Ar/O2 atmosphere. Conventional analytical techniques, such as field emission scanning electron microscopy (FESEM), X-ray diffraction, transmission electron microscopy, photoluminescence spectra and high angle annular dark field image (HAADF) of the as-grown nanostructures confirm tin doping in ZnO single crystals. A possible formation mechanism of the nanostructures was proposed. It was established that the incorporation of Sn in the ZnO branched nanorods significantly improves their sensitivity towards acetone and ethanol vapours. The response and recovery times were measured to be ~7s and ~38s when exposed to 50ppm acetone at the test temperature of 400°C. The acetone and ethanol sensing performance of the doped ZnO nanorod sensors were better than that undoped ZnO nanostructured sensors under comparable operating conditions. The sensitivity/response of acetone and ethanol vapours for Sn-doped hierarchical ZnO nanorod was ascribed to the single-crystalline morphology, increased O-vacancy and other defect density and higher surface areas, which in turn accelerates a fast and effective diffusion process for acetone or ethanol vapours as compared to undoped ZnO nanostructures.