Cobalt Porphyrin Functionalized Carbon Nanotubes for Oxygen Reduction

TitleCobalt Porphyrin Functionalized Carbon Nanotubes for Oxygen Reduction
Publication TypeJournal Article
Year of Publication2009
AuthorsZhang, W, Shaikh, AU, Tsui, EY, Swager, TM
JournalChemistry of Materials
Date Publishedjul
Keywordscobalt porphyrin functionalized carbon nanotube ca, fuel cell cobalt porphyrin functionalized carbon n

Carbon nanotube (CNT) compns. were prepd. by covalently grafting a Co(II) porphyrin to functionalized multiwalled carbon nanotubes (MWCNTs) via zwitterionic functionalization of the CNT sidewalls followed by a SN2 substitution reaction. The MWCNT-Co-porphyrin compns., mixed with Nafion, displayed excellent catalytic performance for oxygen redn. in acidic media (pH = 0.0-5.0) at room temp. With low catalyst loading, the oxygen redn. rates achieved are more than one order of magnitude higher than previously reported values for similar Co-porphyrin catalysts. These results demonstrate the advantages of systems of MWCNTs covalently linked to electrocatalytic mols. The electrodes are easily fabricated by a drop-casting vacuum drying procedure. Rotating disk electrode and rotating ring disk electrode measurements revealed the mechanism to be a direct four-proton and four-electron redn. of oxygen to water. These results demonstrate that new MWCNT electrocatalytic systems are potential substitutes for platinum or other metal-based cathode materials in proton conducting membrane fuel cells. [on SciFinder(R)]