Synthesis and Characterization of Cobalt Nanoparticles, Nanowires and their Composites

I. Markova – Deneva(a), K. Alexandrova, I. Dragieva
a: University of Chemical Technology and Metallurgy, Institute of Electrochemistry and Energy Systems-Bulgarian Academy of Sciences, Sofia, Bulgaria

Abstract

Cobalt (Co) nanoparticles and nanowires were synthesized at room temperature and atmospheric pressure by chemical reduction in aqueous solutions of Co salts with NaBH4. Two types of reactors were used ensuring various hydrodynamic conditions of mixing for both solutions (CoSO4.7H2O solution and NaBH4 solution). Co nanoparticles in amorphous state were synthesized using an ideal mixing conditions reactor (T-method), as well as Co nanoparticles with a crystalline structure in a reactor with an ideal displacement regime (A–method) were synthesized too. From the synthesized Co nanoparticles and micronized AlN powder (10-30 mass %) were prepared composites by pressing and sintering in the temperature range from 550 o to 750 oC for a potential application as getters or catalysts. Co nanowires were synthesized also by reduction in the presence of SiO2, SiMCM и AlMCM supports. The content of B, H2, and O2 by elemental analysis of nanoparticles and their specific surface area by the BET method were determined. Some physical-mechanical properties such as density and electro conductivity of samples of sintered amorphous and crystalline nanoparticles and their composites with micronized AlN powder heat treated in 200 o to 850 oC range were measured. IR spectroscopic studies of Co nanoparticles and their AlN composites were carried out by FTIR in 4000 to 400 cm-1 frequency range, as well as SEM micrographs of the Co nanowires were made which allow determining their diameters.