Development of Novel Electrocatalyst Support In Proton Exchange Membrane Fuel Cells for Automotive Applications
Proton exchange membrane (PEM) fuel cells have received great attention as an alternative power source for transportation and stationary applications. A membrane-electrode-assembly (MEA) that generates electricity by electrochemical reactions consists of proton exchange membrane as an electrolyte and two electrodes for the anode and the cathode, respectively. Pt or Pt alloy catalyst is used to oxidize hydrogen molecule at the anode and to reduce gaseous oxygen at the cathode. Pt or Pt alloy nanoparticles is typically dispersed on high surface area carbon to increase its surface area available for electrochemical reactions. However, carbon oxidation can be thermodynamically favored even at low potentials (> 0.2 V vs. standard hydrogen electrode (SHE)). The corrosion rate of carbon in the presence of Pt nanoparticles greatly increases at positive potentials (> 1.0 V vs. SHE) of the cathode during start-stop cycles.
In this study, durable hybrid electrocatalyst supports for the cathode were developed using graphitized carbons as scaffolds and metal oxides to disperse Pt nanoparticles onto carbon surface protected by metal oxides. The electrochemical property for new electrocatalysts with different hybrid supports was examined using thin film rotating disk electrode (TFRDE). Performance and durability of the cathodes loaded with various electrocatalysts were evaluated under the catalyst support accelerated stress test. A metal oxide modified graphitized carbon resulted in better durability (> 3X) than commercially available catalyst support, thereby showing great promise in becoming alternative and durable electrocatalyst support in PEM fuel cells for transportation applications.
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