Response of a ZnO Single Crystal Rod-Based Chemical Sensor for Hydrogen Sulfide

摘要

A zinc oxide single crystal rod was grown by a thermal evaporation method for application as a chemical gas-sensing material in this study. Zinc acetate (20 wt%) impregnated over activated carbon was used as the precursor for the epitaxial growth of ZnO single crystal rods. The response tests were carried out across a range of sensing temperatures (100, 150 and 200℃) and the hydrogen sulfide content (10.2-51.0 ppmv) was balanced with nitrogen gas. The response of the ZnO single crystal rods grown on the gas sensors varied with the H_2S content and the sensing temperature. A high response for H_2S was obtained at 150 and 200℃ due to the high reactivity between H_2S and ZnO at high temperature. Since H_2S absorption rate and ZnS oxidation rate over ZnO single crystal rods at 100℃ lower than that at 150 and 200℃, the changing rate of electric resistance decreased with the decrease of temperature. Meanwhile, a different response, which is the changing rate of electric resistance for H_2S absorption and ZnS oxidation over ZnO single crystal rods at 100℃, was observed with changing amount of H_2S in feed gas. Therefore, it was concluded that the ZnO single crystal rods based gas sensor is operated above 200℃ for the shortly response time.