385714 Comparison of in-Situ Hydrogen Oxidation Reaction Kinetics for Various Polymer Hydroxide Exchange Electrolytes

Wednesday, November 19, 2014
Galleria Exhibit Hall (Hilton Atlanta)
Mariah Woodroof and Yushan Yan, Chemical & Biomolecular Engineering, University of Delaware, Newark, DE

Previous studies using rotational disk electrode (RDE) and in-situ H2-pump set-ups have shown that the kinetics for the hydrogen oxidation and evolution reactions (HOR/HER) on carbon supported platinum (Pt/C) are on the order of 100x larger in acid than in base. However, no study has been carried out on the difference in io between liquid and solid polymer alkaline systems. In this study, the exchange current density (io), a parameter used to quantify the kinetics of the HOR/HER, was calculated for Pt/C interfaced with a number of hydroxide exchange membranes (HEMs) and ionomers using the Butler-Volmer equation and in-situ kinetic studies. Comparison of the exchange current densities in H2-pump and RDE set-ups allows insight into how the HOR/HER kinetics differ in each system. Initial data with a commercial HEM and ionomer material show the io for Pt/C in a HEM fuel cell to be two times larger than the io measured with RDE, meaning the HEM materials that transport the hydroxide ions to the catalyst surface create a different type of alkaline environment than the liquid electrolyte transporting free hydroxide ions in RDE. Various HEM and respective ionomer materials are substituted into the in-situ H2-pump to observe how different cationic side chains affect the alkaline environment in a HEM fuel cell.

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