A sensing properties study on miniature Au/SnO 2 gas sensor for hydrogen sulfide detection

The purpose of this study was to investigate the sensing properties for self-developed hydrogen sulfide gas sensor. In different temperature treatment and Au nano-particles doping ration, the sensitivity and selectivity of Au/SnO 2 gas sensor were optimized by observing the morphological, electrical and gas sensing properties. The results of experimental showed that on 400°C firing temperature to fabricate SnO 2 sensing film, a linear dependence of the gas sensitivity on the resistivity of the sensor elements was found. The observed shift to higher gas sensitivities in comparison to sensors fired at 300°C or 500°C was caused by smaller crystallite sizes. The optimal crystallite sizes were 50 to 100 nm for improving the gas sensitivity significantly. Also for the doping ratio of Au nano-particles, the Au/SnO2 ratio at 1:100 was found that achieved an optimal sensitivity and selectivity, in this condition the detection range for hydrogen sulfide was about 0.2 to 20 ppm and could be operated at room temperature, and this self-developed gas sensor showed a good selectivity to avoid the interference of SO 2, NH 3, CO 2 or O 2. Even under the alcohol environment, we found there was no significant response to effect the hydrogen sulfide gas detection. However, we found to avoid the moisture interference that was important. Because the water molecules promote the electrical conduct on SnO 2 resistive sensing film that will significant interfere the target gas detection.