Monday, 23 May 2005 - 2:30 PM

This presentation is part of: Solid State and Materials Chemistry II

Graphite Nanofibers in Direct Methanol Fuel Cell Electrodes

Carol A. Bessel1, Donna Omiatek1, Susan Thai1, Georgia C. Papaefthymiou1, Arthur Viescas1, Douglas A. Blom2, and Lawrence F. Allard2. (1) Villanova University, Villanova, PA, (2) Oak Ridge National Laboratory, Oak Ridge, TN

Some of the most easily prepared and least expensive highly crystalline carbon materials are graphite nanofibers (GNFs). These materials are produced catalytically by the decomposition of hydrogen and carbon monoxide and/or selected hydrocarbons on mono- or bimetallic surfaces. The choice of growth catalyst and conditions have enabled the GNF to be tailored to specific technological needs, such as their use as supports for platinum catalyst particles in direct methanol fuel cell (DMFC) anodes. In this presentation, we will discuss the synthesis of the GNF-growth catalysts as well as their resultant GNFs. These materials have been characterized by using HRTEM, SEM, TGA, and Mossbauer spectroscopy. While the commercial practicality of carbon-supported platinum electrocatalysts suffer from requirements of high percent weight loading as well as self-poisoning, we have found that 5 wt% Pt on platelet or ribbon-type GNF exhibit improved activities of 400% when compared with the industry standard, Vulcan carbon-supported platinum. Additionally, self poisoning studies indicate notable decreases with platelet or ribbon GNF compared to Vulcan carbon. The decreases in weight loading and self-poisoning may be attributable to various causes including: a more efficient mechanism for the removal or adsorbed species, increased electrical conductance, decreased impurities in the carbon support and/or a preferred crystallographic orientation of the platinum catalyst particles as a result of the highly ordered GNF morphology. Each of these will be discussed.

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