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Colloidal Polymerization of Polymer-Coated Ferromagnetic Nanoparticles into Cobalt Oxide Nanowires

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journal contribution
posted on 27.10.2009, 00:00 authored by Pei Yuin Keng, Bo Yun Kim, In-Bo Shim, Rabindra Sahoo, Peter E. Veneman, Neal R. Armstrong, Heemin Yoo, Jeanne E. Pemberton, Mathew M. Bull, Jared J. Griebel, Erin L. Ratcliff, Kenneth G. Nebesny, Jeffrey Pyun
The preparation of polystyrene-coated cobalt oxide nanowires is reported via the colloidal polymerization of polymer-coated ferromagnetic cobalt nanoparticles (PS-CoNPs). Using a combination of dipolar nanoparticle assembly and a solution oxidation of preorganized metallic colloids, interconnected nanoparticles of cobalt oxide spanning micrometers in length were prepared. The colloidal polymerization of PS-CoNPs into cobalt oxide (CoO and Co3O4) nanowires was achieved by bubbling O2 into PS-CoNP dispersions in 1,2-dichlorobenzene at 175 °C. Calcination of thin films of PS-coated cobalt oxide nanowires afforded Co3O4 metal oxide materials. Transmission electron microscopy (TEM) revealed the formation of interconnected nanoparticles of cobalt oxide with hollow inclusions, arising from a combination of dipolar assembly of PS-CoNPs and the nanoscale Kirkendall effect in the oxidation reaction. Using a wide range of spectroscopic and electrochemical characterization techniques, we demonstrate that cobalt oxide nanowires prepared via this novel methodology were electroactive with potential applications as nanostructured electrodes for energy storage.