Effect of ethanol gas on the electrical properties of ZnO nanorods

An ethanol gas sensor based on ZnO nanorods was fabricated by hydrothermal synthesis. The structure and morphology of the ZnO nanorods are characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The electrical resistance, capacitance and impedance of the sensor were investigated at room temperature (23 °C) when exposed to air and ethanol gas of different concentrations. When the sensor was transferred from air to 20 ppm ethanol in air the electrical resistance decreased by 67%, the capacitance increased by 122% and the impedance decreased by 56% at the frequency of 100 Hz. The mechanism for the changes in capacitance and impedance as a function of frequency is presented.