Sensing Capability of Air Plasma-Sprayed SnO2 Coating in the Presence of Hydrogen and Carbon Monoxide

This report deals with the sensing characteristics of hydrogen (H-2) and carbon monoxide (CO) gases using a tin oxide (SnO2) functional coating deposited on an alumina plate using air plasma spraying technique. This coating exhibits a porous morphology that contains both mesoporous and macroporous regions conducive to superior gas sensing. Initially, gas sensing measurements were performed by varying the operating temperature at a fixed gas concentration using a dynamic sensing setup. The coating showed maximum response % at 275 degrees C for H-2 and CO gases. However, higher response % was obtained in the presence of H-2 over CO. Sensing performance was further investigated by varying the target gas concentration at 275 degrees C. The coating exhibited a higher response for H-2 compared to that of other plasma-sprayed SnO2 coating reported in the literature. The SnO2 coating under investigation demonstrated good sensor response and repeatability, moderate operating temperature and quick response time.