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    • Keywords


      Electrochemical impedance spectroscopy; membrane electrode assembly; electrochemically active surface area; oxygen reduction reaction; polymer electrolyte fuel cell.

    • Abstract


      New-generation Pt/C-TiO2 nanocomposite electrocatalysts for fuel cells, prepared by a heterogeneous photocatalytic method, have been characterized using techniques such as cyclic voltammetry, rotating disk electrode (RDE) voltammetry, and electrochemical impedance spectroscopy (EIS). Importantly, galvanostatic data confirm the superior stability of these materials against corrosion under anodic polarization conditions relative to commercial benchmark fuel cell electrocatalysts. EIS spectra from ETEK 5, SIDCAT 405 and SIDCAT 410 membrane electrode assemblies (MEAs) were fit to a Randles equivalent circuit with a Warburg element to show the presence of O2 transport limitation arising from the use of thicker electrodes (lower Pt loading on carbon). The use of a constant phase element (CPE) instead of pure capacitor was justified from the fit procedure as CPE represents the porous electrode system more precisely with its distributive elements. EIS spectra from Tanaka, SIDCAT 451 and SIDCAT 452 MEAs (thinner electrodes) were fit to a Randles circuit with a pure capacitor and no Warburg element. The use of a transmission line model for fitting these data independently provided information about the catalyst layer resistance while all other parameters matched well with that of the Randles circuit. The effective proton transport in cathodes was quantified using polarization data for both classes of MEAs. Trends in the previously reported performance of MEAs prepared using these electrocatalysts were justified based on the relative contributions of kinetic, Ohmic and mass transfer losses to the overall overpotential, which in turn were estimated from impedance and polarization data analyses.

    • Author Affiliations


      Satheesh Sambandam1 Vinodh Valluri2 Wilaiwan Chanmanee2 Norma R De Tacconi2 Wesley A Wampler3 Wen-Yuan Lin3 Thomas F Carlson3 Vijay Ramani1 Krishnan Rajeshwar2

      1. Center for Electrochemical Science and Engineering, Department of Chemical Biological Engineering, Illinois Institute of Technology, Chicago, Illinois 60616, USA
      2. Center for Renewable Energy Science and Technology (CREST), University of Texas at Arlington, Arlington, TX 76019, USA
      3. Sid Richardson Carbon and Energy Company, Fort Worth, TX 76106, USA
    • Dates

  • Journal of Chemical Sciences | News

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