Mahmoud Omari

Synthesis and electrochemical properties of mesoporous La1−xMgxAlO3−δ nanopowders by sol-gel method

ABSTRACT In this work, oxides mesoporous La1−xMgxAlO3−δ (0 ≤ x ≤ 0.15) nanopowders were synthesized by sol-gel method. The properties of these powders were characterized with several analytical techniques including thermogravimetric and differential thermal analysis, X-ray diffractometry, infrared spectroscopy, scanning electron microscopy, Brunauer–Emmett–Teller analysis, and Barrett–Joyner–Halenda analysis. After the precursor was further calcined at 800°C for 6 h in air, a single-phase perovskite, La1−xMgxAlO3−δ (0 ≤ x ≤ 0.15), was formed without any traceable impurities based on XRD diffraction analysis. Surface areas, pore diameters, and crystallite sizes are in the 12.9–20 m2 g−1, 8.8–11.28 and 25.4–30.5 nm ranges, respectively. Taking into consideration the possible application of these compounds as catalysts in direct methanol fuel cells, their catalytic properties toward oxidation of methanol in the basic solutions were studied by cyclic voltammetry. La0.85Mg0.15AlO3 modified electrodes responded extremely well to methanol by giving high anodic current for methanol oxidation.

Thermal behavior and phase formation of the strontium cobalt oxides prepared via Sol-Gel method

Our contribution has focused on the synthesis and characterization of strontium cobalt SrCoO3-δ oxide by the Sol-Gel method. The powder was successfully synthesized using citric acid, Sr (NO3)2 and Co (NO3)2.6H2O as raw materials by this method and calcined at different temperatures. It was characterized by several techniques: Fourier transform infrared spectroscopy (FT-IR), thermogravimetric and differential thermal analysis (TGA/DTA), X-ray diffraction (XRD) and laser diffusion. All the results for physico-chemicals characterizations show that the crystallization temperature of the SrCoO3-δ precursor gels is estimated as 900 °C by TG/DTA. The XRD pattern of the SrCoO3-δ precursor gels calcined at 950 °C for 6 h has a perovskite structure of rhombohedral phase formed and the presence of crystalline impurities is not found. The crystallite size of SrCoO3-δ slightly increases from 23,02 to 38,13 nm with calcination temperature increasing from 750 to1050 °C for 6 h.