Abstract
A well-designed cathode catalyst layer with optimal ionomer distribution is critical to minimizing amount of Platinum (Pt) content in polymer electrolyte fuel cells (PEFCs). The impact of Pt loading, ionomer content and carbon support types on the catalyst/ionomer interface were also investigated at dry and wet conditions. Higher Pt loadings resulted in higher double layer capacity (Cdl) and similar electrochemical surface area (ECSA) due to well dispersed ionic phase material. Higher ionomer content resulted in higher ionic conductivity but also showed similar group coverage. High surface area (HSA) carbon support had larger ECSA and Cdl at both dry and wet conditions, as less agglomerated Pt was well dispersed in the meso-pores of the support. Lower group coverages were observed for HSA carbon than for Vulcan carbon due to Pt particles being buried within the porous HSA carbon support. The effect of cell conditioning and voltage recovery on the PEFC cathode catalyst layer was shown to have minimal impact on group coverage despite a decrease in Cdl and ECSA due to the size increase of Pt particles. At dry condition, a significant increases in group coverage were observed for all MEAs due to higher adsorptivity of ionomer in dry conditions.
Published Version
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