Fabrication and ethanol sensing of sol–gel grown zinc oxide powder: the effect of cobalt and copper doping

Pure, cobalt and copper doped zinc oxide powder were successfully fabricated by the sol–gel method at different concentrations (i.e., 5 wt% and 10 wt%). Structural and morphological properties of the samples were studied comparatively. Structural analysis of the samples revealed that all of them were polycrystalline zinc oxide in nature; possessing hexagonal wurtzite structure with (101) preferred orientation. The lattice constants were calculated from the most prominent peak and compared with the standard values. Other structural parameters such as strain, crystallite size, dislocation density, stacking fault, and specific surface area were also calculated to have a better investigation. The sensing performance of the samples toward ethanol vapors was investigated for various concentrations of ethanol in air at different operating temperatures in the range of 175–400 °C. The gas sensing performance of the samples was evaluated in terms of gas concentration and operating temperature. Compared to pure zinc oxide, a drastic reduction in the optimal operating temperature and the recovery time was observed after doping. If four different parameters (operating temperature, dynamic response, sensitivity and response and recovery times) were considered simultaneously, the ZCo10 (10% cobalt doped) can be a good option as a sensor material.