Synthesis, characterization, and electrocatalytic properties of La0.9Sr0.1Cr1-x Co x O3 perovskite oxides

Polycrystalline La0.9Sr0.1Cr1-x Co (x) O-3 (0.0 ae<currency> x ae<currency> 0.4) solid solutions were synthesized by a sol-gel method using citric acid as chelating agent. Thermogravimetric and differential thermal analysis, Fourier-transform infrared spectroscopy, and X-ray diffraction (XRD) techniques are used to explore precursor decomposition and to establish adequate calcination temperature for the preparation of the polycrystalline. The samples obtained after calcination at 750 A degrees C were characterized by several techniques. X-ray diffraction analyses reveal that that B-site doping of Co may lead to the transformation of its crystal structure from an orthorhombic to a rhombohedral phase, when Co content x ae<yen> 0.2. Scanning electron microscopy (SEM) shows that all samples have almost spherical nanoparticles with high crystallization. The increase in the fraction of the doped-Co leads to high agglomeration of particles while the porosity increases. Electrochemical measurements indicate that the catalytic activity toward methanol oxidation in alkaline solution is strongly influenced by cobalt doping. La0.9Sr0.1Cr0.6Co0.4O3-modified electrodes responded extremely well to methanol by giving high anodic current for methanol oxidation (over 46 mA cm(-2) at 0.650 V vs Hg/HgO).