Cobalt Porphyrin Functionalized Carbon Nanotubes for Oxygen Reduction

Abstract

Carbon nanotube (CNT) compositions were prepared by covalently grafting a Co(II) porphyrin to functionalized multiwalled carbon nanotubes (MWCNTs) via zwitterionic functionalization of the CNT sidewalls followed by a S N 2 substitution reaction. The MWCNT-Co-porphyrin compositions, mixed with Nafion, displayed excellent catalytic performance for oxygen reduction in acidic media (pH range, 0.0-5.0) at room temperature. With low catalyst loading, the oxygen reduction rates achieved are more than 1 order of magnitude higher than previously reported values for similar Coporphyrin catalysts. These results demonstrate the advantages of systems of MWCNTs covalently linked to electrocatalytic molecules. The electrodes are easily fabricated by a drop-casting vacuum drying procedure. Rotating disk electrode (RDE) and rotating ring disk electrode (RRDE) measurements revealed the mechanism to be a direct four-proton and four-electron reduction 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.

Electrochemical detection of dioxygen and hydrogen peroxide by hemin immobilized on chemically converted graphene

“…For fabricating the electrochemical sensors of these compounds, iron or cobalt porphyrins are recognized as good probing molecules [6][7][8][9][10][11][12][13]. Among them, hemin (ferriprotoporphyrin IX), the active center of hemoglobin has been widely used, because it is cheap, stable and able to catalyze the reduction reactions of O 2 and H 2 O 2 .…”

Sensitive biosensing strategy based on functional nanomaterials

“…For example, MWNT-cobalt porphyrin compositions display excellent catalytic performance for oxygen reduction in acidic media at room temperature [39]. With low catalyst loading, the oxygen reduction rates are more than 1 order of magnitude, higher than previously reported values for free cobalt porphyrin catalysts.…”

Optical and electrochemical behavior of new nano-sized complexes based on gold-colloid and Co-porphyrin derivative in the presence of H 2 O 2

“…The same catalytic performance for oxygen reduction in high acidic media, at room temperature, was obtained by grafting a Co(II) porphyrin onto multiwalled carbon nanotubes [8] and onto the network of three-dimensionally distributed gold (polyoxometallate-modified) nanoparticles producing cobalt porphyrin-hybrid multi-layered film with high activity toward electroreduction of hydrogen peroxide [9]. Electroactive hybrid films of gold colloid nanoparticles and cobalt porphyrins fabricated with layer-by-layer assembly method showed catalytic activity toward the oxygen reduction.…”