Highly sensitive gold-decorated zinc oxide nanorods sensor for triethylamine working at near room temperature

There is an increasing worldwide demand for chemiresistive sensors for specific gas working at low temperature, in particular for standalone and mobile systems, which call for small and low power devices. In this paper, we successfully assemble highly sensitive triethylamine (TEA) gas sensors working at near-room temperature with gold (Au)-decorated ZnO nanorods. ZnO nanorods grow directly on flat Al₂O₃ ceramic electrodes by a cost-effective hydrothermal method and Au nanoparticles are deposited onto ZnO nanorods by DC-sputtering. Au-loaded ZnO (Au/ZnO) nanorods sensor at working temperature of 40°C and relative humidity of 30% exhibits high response (22-50ppm TEA), low detection concentration (∼1ppm), and short response/recovery time (11s/15s), which are all much better than the pristine ZnO nanorods sensor. When the relative humidity increases, the sensor response decreases due to the water molecules adsorption. Moreover, the enhanced sensing properties of the Au/ZnO sensors are discussed in detail with the semiconductor depletion layer model introduced by the Au/ZnO Schottky contact and the catalytic effect of noble gold nanoparticles.