Highly sensitive and selective butanone sensors based on cerium-doped SnO2 thin films

Tin oxide (SnO2) thin films, doped with different concentrations of cerium (Ce), were prepared via a simple sol-gel and dip-coating technique. The surface morphologies and microstructures of the thin films were characterized by field emission scanning electron microscope, atomic force microscopy, X-ray diffraction and Raman spectra. It was revealed that the Ce-doped SnO2 thin films with rougher surface were composed of smaller crystallites compared with undoped ones. The disordered structures and boundaries of the Ce-doped SnO2 thin films were also enhanced. Furthermore, the influence factors of gas-sensing properties for butanone, such as cerium concentration, calcination temperature, the layers of thin films and humidity, were investigated. The results indicated that four-layer 1 at% Ce-doped SnO2 thin films calcined at 500 degrees C presented the best response. At the optimal working temperature of 210 degrees C, the response to 100 ppm of butanone vapor was about 181 in dry air. In addition, the gas sensor had a good selectivity for butanone. Finally, the possible mechanism of the Ce addition on the gas-sensing properties was also discussed. (C) 2010 Elsevier B.V. All rights reserved.