A simple approach for the synthesis of Co3O4 nanocrystals

By using Co2+ and Co3+ salts, and freshly extracted ovalbumin, Co3O4 nanocrystals have been synthesized successfully. The pH of the solution was self-regulated for the hydrolysis of metal ions as the ovalbumin-water mixture was highly basic. Water soluble ovalbumin proteins served as a perfect matrix for entrapment of Co2+ and Co3+ ions thus forming a gel. Upon heat treatment, the dried gel precursor decomposed into nanocrystalline Co3O4. The crystallite size obtained by XRD line profile fitting was 45 +/- 8 nm and particle size estimated from the SEM was in the range 20 nm-2 mu m. EPR results show a very good fit to literature reports for nanocrystals in the size range of 8-17 nm. Even though the overall particle size is quite large and its distribution is quite wide EPR results confirm nanocrystalline nature of the particles obtained. Presented route is simple, cost effective, and environmentally friendly.