Origin of improved sensitivity in conductometric ethanol sensor based on ZnO aerogel nanoparticles

Abstract In this study, ZnO nanoparticles (NPs) for gas sensing were synthesised using a modified sol–gel technique. X-ray diffraction (XRD), transmission electron microscopy (TEM), photoluminescence (PL), Raman, scanning electron microscopy (SEM) combined with x-ray spectroscopy (EDX), and x-ray photoelectron spectrometry (XPS) were used for analysing their characteristics. The research results demonstrated the hexagonal wurtzite structure of the produced nanoparticles, characterised by a uniform shape and size distribution. Furthermore, the EDX analysis confirmed the elemental composition of the ZnO nanoparticles, which showed that these nanoparticles were mainly composed of Zn and O elements, with a slight oxygen deficiency, explained by the presence of oxygen vacancies due to the applied protocol. This finding was confirmed by PL, Raman, and XPS characterisations. After that, using the nanoparticles, a thick film gas sensor was created to detect ethanol as a volatile organic compound (VOC) and assess how well it performed at various temperatures between 250 and 450 °C At 450 °C operating temperature and 500 ppm ethanol concentration, the sensor demonstrated strong selectivity, high sensitivity, and comparatively quick response and recovery time. Our research indicates that ZnO nanoparticles developed using this technique have the potential to be a highly sensitive and selective sensor for detecting ethanol gas, exhibiting rapid dynamics at operating temperatures. Compared to methanol, acetone, and isopropanol, ethanol exhibited stronger gas sensor performance.