Generation of Co3O4 microparticles by solution combustion method and its Zn-Co3O4 composite thin films for corrosion protection

Microcrystalline cobalt oxide (Co3O4) powder was successfully synthesized by a simple, fast, economical and eco-friendly solution-combustion method. The as-synthesized powder was calcined for an hour at temperatures ranging from 100 to 900 degrees C. The crystallite size, morphology, and chemical state of synthesized powders were characterized by powder XRD, TG-DTA, XPS, SEM/EDAX, TEM and FT-IR spectral methods. The as-synthesized Co3O4 powder was single-crystalline and Rietveld refinement of calcined samples exhibited cubic structure with space group of Fm3m (No. 227). The effect of calcination temperature on crystallite size and morphology was assessed. Scanning electron micrographs show a uniform, randomly oriented pseudo-cubic particle with porous like morphology and EDAX measurement showed its chemical composition. Thermal behavior of as-synthesized compound was examined. The TEM result revealed that, the particles are pseudo-cubic in nature with diameter of 0.2-0.6 mu m and a length of 0.9-1.2 mu m. The crystallite size increased with increase of calcination temperature. The synthesized Co3O4 powder was used to fabricate Zn-Co3O4 composite thin films and its corrosion behavior was analyzed by anodic polarization, tafel extrapolation and electrochemical impedance spectroscopy. The results indicate that the Zn-Co3O4 composite thin films have potential applications to corrosion protection. (C) 2012 Elsevier B. V. All rights reserved.