Sn/In/Ti nanocomposite sensor for CH4 detection

Novel CH4 gas sensors made of the nanocomposites of Sn/In/Ti oxides were investigated. The nanosized crystalline oxides and their composites were successfully prepared by a sol–gel and controlled precipitation method, respectively, through manipulating the salts concentration, precipitation pH value, aging time and composition of composites. The derived precursors exhibited superior thermal stability. To ensure sufficient crystallinity and insignificant grain growth of the materials, the appropriate calcination temperatures were 600 °C for 4 h and 700 °C for 2 h for the precursors of oxides and composites, respectively. The performance and structure of the composites were characterized by EDX, TEM, BET, TG–DTA and XRD. The sensing tests showed that these nanocomposites exhibited high response and selectivity for the detection of CH4 at operating temperatures between 200 °C and 250 °C and the response depended on the composition of composites, calcination temperature, operating temperature and gas concentration in air. The gas sensing mechanism of the sensors was also discussed by X-ray photoelectron spectroscopic (XPS) and temperature-programmed desorption (TPD) studies.