Study on ethanel gas sensing properties of Sn-doped ZnO thick film

Pure ZnO and 5at%, 7at%, 9at% Sn-doped ZnO precursors were prepared by the chemical co-precipitation method. Different Sn-doped ZnO powers were obtained by annealing. The crystal structure and surface topography of different samples were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Gas sensors were prepared by dip coating method. The sensing properties were tested. The results show that the Sn-doped ZnO materials appear rough porous structures with the hexagonal wurtzite. The particle size distribution was uniform. The maximum sensitivity could be achieved by doping the amount of 7at%. It has much better sensing performance towards ethanol vapor under visible light irradiation. The response and recovery time were 1 s and 5 s, respectively. The sensitivity is 400. The mechanism for the improvement in the sensing properties could be explained with the surface adsorption theory and the photoactivation theory.