Sol-gel synthesis and characterization of cobalt oxide-based nanosystems

Nanocrystalline cobalt oxide films (CoO, Co3O4) and CoO-doped silica coatings were prepared via sol-gel using cobalt acetate [Co(CH3COO)2.4H2O] and tetraethoxysilane [Si(OC2H5)4, (TEOS)] as starting compounds. Pure CoO layers were obtained after dip-coating from alcoholic solutions of cobalt acetate and annealing in H2/Ar atmosphere (200-700°C), while treatments in air or nitrogen (100-700°C) resulted in the formation of nanocrystalline Co3O4. Nanocomposite silica glass coatings containing CoO were also prepared starting from alcoholic solutions of TEOS and cobalt acetate and subsequently annealed at different temperatures (300-900° C) in air. Some relevant results concerning the composition and microstructure of the systems are presented and discussed.