Probing the Electrochemical Characteristics of Aged Carbon- Supported Pt Catalysts

Undergraduate #114
Discipline: Technology and Engineering
Subcategory: Chemistry (not Biochemistry)

Andre' Spears - Southern University and A&M College
Co-Author(s): Anthony Stewart, Allen University, Columbia, SC Joseph Dumont, University of New Mexico, Albuquerque, NM Tommy Rockward, Los Alamos National Laboratory, Los Alamos, NM

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In this work we have investigated the effects of aging, by using an Accelerated Stress Test (AST) which consists of voltage cycles from 0.015 V to 1.5 V (V-cycling), on the electrochemically active surface area (EASA) of different types of carbon-supported platinum catalysts. In particular, we employed catalysts supported on two high surface area carbons: XC-72 and graphitized carbon. Both materials are used in the state-of-theart Proton Exchange Membrane Fuel Cells (PEMFCs). We show a direct correlation between EASA and V-cycling, by utilizing the chemisorption of carbon monoxide and its subsequent oxidation to quantify the active catalyst surface area. These results were obtained by measuring electrochemical characteristics of the catalysts deposited on glassy carbon substrates using various electrochemical techniques such as cyclic voltammetry (CV) and potential step method. Detailed examination of the results has shown that the type of carbon support material plays a critical role in sustaining the catalyst’s morphology. This was demonstrated by growth in the so-called double layer region of the CVs, which is indicative of carbon corrosion. In both cases we observed EASA losses as the number of V-cycles increased; however, the rate and extent was higher for XC-72 supported catalyst.

Funder Acknowledgement(s): U.S. Department of Energy / National Nuclear Science Administration / Consortium of Materials and Energy Studies

Faculty Advisor: Diola Bagayoko,