Hydrogen sensing characteristics of Pt–SnO₂ nano-structured composite thin films

This paper reports the preparation of Pt–SnO₂ composite thin film gas sensors for the detection of H₂ gas having lower concentration (150 ppm) at relatively lower operating temperature of 85 °C. Nano crystalline tin oxide (SnO₂) thin films were prepared by simple spin coating technique. Subsequently platinum thin film was sputtered over the SnO₂ thin film to get the Pt–SnO₂ composite thin films. The structural, nano structural and gas sensing properties of both SnO₂ and Pt–SnO₂ thin film sensor were studied. XRD indicate the formation of tetragonal SnO₂ where as in case of Pt–SnO₂ the existence of cubic SnPt₃ was observed. A comparative study of the hydrogen sensing properties viz. operating temperature, response and recovery time and selectivity was carried out. Due to Pt loading, the sensor showed reduction in the operating temperature to 85 °C with good modulation and response time of 0.5 s to H₂ gas. The response to other gases such as carbon monoxide (CO) and LPG (at 150 ppm) of the Pt–SnO₂ composite thin film sensor were also investigated. The sensor showed highest response to H₂ gas where as lowest response was noted for CO gas.