Effect of Cathode Catalyst Layer Structure on the Performance of PEFC

Reducing the Platinum utilization in PEFC is one route for its commercialization, by reducing the cathode platinum loading, and/or increase in its specific reaction catalytic activity. However, the effectiveness factor has an inherent relation with current density and reactants mass transfer. Two dimensionless moduli, representing diffusion limitations have been used to investigate cathode behaviour. Experiments were carried out with varying cathode catalyst layer (CCL) structure. The membrane electrode assembly (MEA) consisted of a Nafion membrane (NR-212, 50 μm) with Pt weight fraction of 0.30, 0.40 and 0.50 in 10 μm CCL. The CCL was prepared by two methods; (1) Pt particles were supported on carbon relevant to the required Pt/C ratio, (2) lower Pt contents were manipulated by adding carbon black (CB) to a prepared catalyst containing 50 wt.% Pt. The results showed proton transport resistance is the key parameter affected by the platinum inhomogeneity within the CCL.