Colloidal polymerization of polymer-coated ferromagnetic cobalt nanoparticles into Pt-Co3O4 nanowires

Pei Yuin Keng, Mathew M. Bull, In Bo Shim, Kenneth G. Nebesny, Neal R. Armstrong, Younghun Sung, Kookheon Char, Jeffrey Pyun

Research output: Contribution to journalArticlepeer-review

46 Scopus citations


In this report, functional one-dimensional (1-D) Pt-Co3O 4 heterostruc-tures with enhanced electrochemical properties were synthesized via colloidal polymerization of polymer-coated ferromagnetic cobalt nanoparticles (PS-CoNPs). Colloidal polymerization of dipolar nanoparticles into hollow metal-semiconductor nanowires was achieved via a consecutive galvanic replacement reaction between Co0 and Pt2+ precursors, followed by a nanoscale Kirkendall oxidation reaction and a calcination treatment. X-ray diffraction (XRD), transmission electron microscopy (TEM), high-angle annular dark field scanning TEM (HAADF-STEM), and field-emission scanning electron microscopy (FESEM) revealed the structural and morphological evolution of the hollow cobalt oxide nanowires (D = 40 nm) with platinum nanoparticles (PtNPs; D ∼ 2 nm) entrapped within the growing oxide shell. Various calcination conditions were investigated via X-ray photoelectron spectroscopy (XPS) to obtain the optimal surface composition of the metallic Pt and semiconducting Co3O4 phases. Cyclic voltammetry of the 1-D Pt-Co3O4 heterostructures demonstrated a sevenfold enhancement in specific capacitance in comparison to the pristine Co 3O4 nanowires. Preliminary results also showed that the calcined 1-D Pt-Co3O4 heterostructures catalytically hydrogenate methyl orange, and the rates of the hydrogenation were dependent on surface composition.(Figure Presented)

Original languageEnglish (US)
Pages (from-to)1120-1129
Number of pages10
JournalChemistry of Materials
Issue number5
StatePublished - Mar 8 2011


  • colloids
  • hybrid inorganic/organic materials
  • magnetic materials

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)
  • Materials Chemistry


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