High Sensitivity Ethanol Gas Sensor Based on Sn-doped ZnO Under Visible Light Irradiation at Low Temperature

Pure ZnO and 5at%, 7at%, 9at% Sn-doped ZnO materials are prepared by the chemical co-precipitation method. They were annealed by furnace at temperature range of 300-700 degrees C in air for 1h. The ZnO materials are characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results show that the Sn-doped ZnO materials appear rough porous structures. The maximum sensitivity can be achieved by doping the amount of 7 at%. It has much better sensing performance towards ethanol vapor under visible light irradiation. The response and recovery time are similar to 1s and similar to 5s, respectively. The mechanism for the improvement in the sensing properties can be explained with the surface adsorption theory and the photoactivation theory.