Liquefied petroleum gas (LPG) sensing properties of nanocrystalline CdO thin films prepared by chemical route: Effect of molarities of precursor solution

We report synthesis of cadmium oxide (CdO) thin films by a simple, inexpensive chemical bath deposition (CBD) method and their application to a liquefied petroleum gas (LPG) sensor. The dependence of LPG sensing properties on the structural and surface morphological properties has been studied. The structural and surface morphological properties of the films were studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The CdO films were highly oriented along (1 1 1) and (2 0 0) with the cubic crystal structure. The SEM observation reveals that porous nano-fibrous structure of CdO is grown, but the thickness increases as the molarity of the Cd2+ precursor increases and the film becomes nearly flat. The mechanism of LPG sensing by the CdO thin film is explained on the basis of adsorbed oxygen on the sensor surface. The maximum response of 23.28% to 0.2 vol.% of LPG was observed at 698 K with the CdO film deposited using a 0.15 M Cd2+ precursor solution.