Highly sensitive gallia-SnO2 nanocomposite sensors to CO and ethanol in presence of methane

Responses of gallia-SnO2 nanocomposite sensors, containing 0–50 wt% Ga2O3 calcined at 500–850 °C, to CO, methane and ethanol are investigated. The gallia-SnO2 samples were prepared via a facile co-precipitation method using stannic chloride and gallium nitrate aqueous solutions without any template and characterized by XRD, EDX, TEM, PL and BET surface area techniques. The samples containing up to 25 wt% gallia and calcined at 500 °C indicate that only tetragonal rutile structure of SnO2 is formed. The Ga4SnO8 and β-Ga2O3 phases are observed for the samples containing 50 wt% Ga2O3 and calcined at 850 and 1050 °C, respectively. The average particle sizes of the nanocomposites gradually decrease from 21.6 to 6.7 nm, as their gallia contents increase from 0 to 25 wt%. The highest responses of 315 and 119 are observed for 300 ppm CO and ethanol by the sensors containing 5 and 1 wt% Ga2O3, respectively. The sensors containing 25 wt% Ga2O3 calcined at 850 °C and 50 wt% gallia calcined at 500 and 850 °C are selective to CO and show negligible responses to ethanol and methane.