CH4 Sensor of Sn, In, and Ti Nanosized Oxides

A novel CH₄ gas sensor based on the nanocomposites and mixed oxides of Sn, In, and Ti, workable at near room temperature, were developed. The binary and ternary oxides were prepared by a chemical controlled step precipitation method and mixed route. The preparation parameters-salt concentration, cation ratio, precipitation pH, and aging time-have been optimized, and their optimal value were 0.05 M, 20% Ti: 20% In: 60% Sn, pH=8.0 and aged 24 h, respectively. The appropriate calcinations temperature for precursor and mixture were 600 degC 4 h and 700 degC 2 h. The performance and structure of the materials were characterized by TEM, BET, TG-DTA, XRD, TPD, and XPS. The sensing tests showed that these nanomaterials exhibited high sensitivity and selectivity for CH₄ and their sensing properties depended on the oxide composition, calcinations temperature, operating temperature, and gas concentration. The gas-sensing mechanism of the sensor was also discussed by TPD and XPS analysis