In this research the effect of the thickness of Ag catalyst layer on the sensing response of tin oxide as a hydrogen gas sensor was investigated. First Ag layer of different thicknesses was sputtered on the client base glass and then sensitive tin oxide layer was sprayed on the Ag catalyst layer. So, the samples with Ag catalyst thicknesses of 10, 20 and 30 nm were fabricated. The sensing responses of the sensors with Ag catalyst and without catalyst layer were measured in response to various concentrations of hydrogen gas at different temperatures. It is observed that the response of the sensors with Ag catalyst increased significantly compared to the sensor without catalyst layer. An interesting result of the experiment shows that the sensing response of tin oxide sensor with 20 nm thickness of Ag catalyst was 52% at 250 °c while the response of the sensor without catalyst was 18% when exposed to 1500 ppm hydrogen gas, exhibiting the high performance of the sensor with appropriate thickness of Ag as catalyst.
