Hydrogen sensing characteristics of WO3 thin film conductometric sensors activated by Pt and Au catalysts

The hydrogen gas sensing performance of platinum (Pt) and gold (Au) catalyst activated WO3 thin films were investigated. The WO3 thin films were deposited onto alumina transducers with platinum inter-digital electrodes using a R.F. magnetron sputtering. Exposure to hydrogen gas, results in changes in the carrier concentration and hence, the conductivity of the film. The sensors were found to exhibit excellent sensitivities towards different hydrogen concentrations of 0.125, 0.25, 0.50 and 1% in air. The effects of different operating temperatures on the sensitivity of the devices were studied in the range of 30–300 °C. It was observed that the Pt–WO3 and Au–WO3 sensors were approximately 161 and 40 times more sensitive than the non-activated WO3 sensor, respectively. In this paper, the effect of temperature dependence on response magnitude and the influence of the metal activator layers for hydrogen gas sensitivity are presented and discussed.