Electrical and CO gas sensing properties of nanostructured La1-xCexCoO3 perovskite prepared by activated reactive synthesis

A series of nanostructred La1-xCexCoO3 perovskite-type (x ranging from 0 to 0.2), with a crystallite size of around 10 nm and a specific surface area of up to 55 m(2)/g were prepared using the activated reactive grinding method. XRD results showed that Ce segregates as CeO2 when the addition level exceeds 10 at%. CO was chosen as a typical reducing gas and its interaction with surface oxygen was investigated. TPD-O-2 was used to investigate the effect of Ce-doping on total surface oxygen. The experimental results confirmed a positive effect of Ce-doping of up to 10 at% on total surface oxygen (alpha-O-2). TPD-CO and XPS analyses were performed to find the total carbon adsorption (i.e. related to the adsorption of CO) on the surface of the synthesized samples. Both methods confirmed that more carbon adsorbs on the surface of doped formulations compared to the pure LaCoO3. Ce-doping increases the surface oxygen, thereby facilitating the adsorption and oxidation processes. CO gas sensing properties of thick La1-xCexCoO3 films were performed. La0.9Ce0.1CoO3 showed the highest conductivity and the lowest activation energy. The optimum CO sensing temperature for doped formulation was found to be 100 degrees C compared to 130 degrees C for pure perovskite. Ce-doped samples showed a maximum response ratio of 240% with respect to 100 ppm CO in air compared to 60% obtained with pure LaCoO3. (C) 2011 Elsevier B.V. All rights reserved.