Center for Functional Nanomaterials Seminar
"Ionomer-Grafted Mesoporous Carbon / Zirconia Nanocomposites"
Presented by Jung-Min Oh, Department of Chemistry, Clemson University
Friday, April 12, 2013, 11 am
CFN, Bldg 735, Conference Room A
Hosted by: James Dickerson
Electrodes in polymer electrolyte membrane fuel cells employ composite electrode systems, which are composed of electrochemically active, electronically conductive, and ionically conductive components. Typical electrodes in these devices are prepared by spraying or painting inks that are obtained by simply blending a carbon-supported electrocatalyst with an ionomer solution. In such electrodes, it can be difficult to achieve intimate integration of ionomer with electrode, and gradual loss in contact between electrode and ionomer may take place and consequently degrade the cell performance over time. One possible way to resolve this problem would be to modify the carbon supports with ionomers by covalent bonding. This talk will describe work on grafting ionomers onto mesoporous carbon-based electrocatalyst supports. Mesoporous carbon supports are prepared using the resorcinol-formaldehyde method with both silica and zirconia sols added and followed by wet chemical etching to remove silica but not zirconia. The resulting supports are mesoporous carbons containing nanoscale zirconia embedded in the carbon skeleton.1 The ionomers that we employed are telechelic perfluorocyclobutyl (PFCB)-aryl-ether oligomers bearing sulfonic acid groups in the main chain and phenylphosphonic acid groups at the end sites.2 Upon exposure of the carbon / zirconia composites to a solution of the telechelic ionomer, grafting of the PFCB ionomers onto the composites can be achieved via covalent binding of the phosphonate end groups of the ionomer onto the exposed zirconia nanoparticles in the carbon skeleton. Preparation and characterization of carbon / zirconia nanocomposites, telechelic PFCB-based ionomers, and ionomer-modified composite-supported electrocatalysts will be discussed. References 1. Oh, J.-M.; Kumbhar, A. S.; Geiculescu, O.E. ; Creager, S. E., Mesoporous Carbon/Zirconia Composites: A Potential Route to Chemically Functionalized