Investigation of the Performance of PtCo/C Cathode Catalyst Layers for ORR Activity and Rated Power for Automotive Pemfcs
Authors: Neyerlin K.C. , Zack Jason W. , Macauley Natalia , Mukundan Rangachary , Borup Rod L. , More Karren L. , Kocha Shyam S. 
Published: February 2020

In order to simultaneously meet the automotive PEMFC targets of cost, performance and durability, Pt-alloys electrocatalysts are being intensively investigated.1,2,3 Pt-alloys show promise of higher ORR mass activities that will permit the use of lower Pt loadings (~0.1 mgPt/cm2) in the cathode catalyst layers. In this work we have studied several Pt-Co/C catalysts that exhibit mass activities that exceed the DOE target of 440 mA/mgPt at 0.90V, 80oC, 100% RH for ORR activity. The performance at rated power density of 1W/cm2 at 0.60V is more difficult to achieve at low loadings due to unanticipated transport resistances. In addition to carrying out ORR activity studies both in TF-RDE set-ups4,5 as well as in MEAs of subscale cells, we have also applied complementary diagnostics of wet and dry H2-Air curves, microscopy of catalyst powders and catalyst layer films, EIS and dilute oxygen limiting current studies6 on these materials. Rigorous base-lining was carried out to obtain the ORR activity of a commercial Pt/C catalyst in order to benchmark the Pt-Co/C catalysts under study using identical protocols.7,8 Although we easily achieve the mass activity targets at 0.90V, we only approach the rated power targets indicating that further understanding of the transport resistances at high current densities and low Pt loadings is necessary to identify and mitigate the losses.

Acknowledgements: This work was funded through the DOE FC-PAD Consortium.

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