Investigation of various ionomer-coated carbon supports for direct methanol fuel cell applications

High-performance fuel cell electrodes require architectures that offer appropriate electrochemical and nanoscopic catalytic reaction zones. In this direction, ionomer (perfluoro sulfonic acid)-coated carbon supports were prepared by adopting a simple and cheap synthetic strategy to offer both electronic and protonic contacts to the catalyst particulates. Pt-Ru bimetallic anode catalysts were prepared on these modified carbon supports by a colloidal method. The role of surface area of carbon supports and the influence of ionomer content in them towards the catalytic activities of Pt-Ru catalysts has been probed by using three kinds of carbon black powders with different physical properties. Their electrocatalytic efficiencies toward methanol oxidation were scrutinized via half-cell measurements in cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy. Catalysts particulates dispersed on carbon supports coated with ionomer exhibited better performance than those on the plain carbon supports, owing to the reduced micropores and increased interfacial area between catalyst particles and ionomer. Plain and modified carbon (MC) supports were characterized by using FTIR, BET-PSD and TEM techniques. Physico-chemical characterizations of supported catalyst systems were done by using XRD and TEM. (C) 2007 Elsevier B.V. All rights reserved.