Alcohols and acetone sensing properties of SnO2 thin films deposited by dip-coating

SnO2 thin films were prepared by dip-coating from SnO2 sols of 0.5 and 0.1 mol/l. The structure and morphology of the films were analyzed through XRD, UV and AFM methods. The particles in the films were the standard tetragonal phase of SnO2 with spherical morphology. The average size of SnO2 particles was about 87 nm (0.5 mol/l) and 5 nm (0.1 mol/l), respectively. The UV absorbance of the films increased linearly with increasing the deposition layers. The sensitivity of thin films to methanol, ethanol, propanol and acetone was detected at room temperature, and the effects of concentration of SnO2 sols on the morphology and sensitivity of the films were investigated as well. With decreasing the sol concentration, the grain size of the particles reduced, the gas sensing properties to acetone and ethanol increased. Such films with small size could detect ethanol as low as 2 ppm ethanol. Response and recovery time to methanol, ethanol, propanol and acetone at room temperature were within 30 s and 1 min, respectively.