Abstract
The commercial success of polymer electrolyte fuel cells (PEFCs) depends on the development of Pt-based oxygen reduction reaction (ORR) catalysts with greater activity and stability to reduce the amount of expensive noble metal per device. To advance toward this goal, we have tested a novel class of unsupported bimetallic alloy catalysts (aerogels) as the cathode material in PEFCs under two accelerated stress test conditions and compared it to a state-of-the-art carbon-supported benchmark (Pt/C). The investigated Pt3Ni aerogel shows little degradation under high potential conditions (> 1.0 V) which can occur during fuel starvation and start-up/shut-down of the cell. If tested under the same conditions, the Pt/C benchmark displays significant losses of electrochemical surface area and ORR activity due to carbon support corrosion as observed in cross section and transmission electron microscopy analysis. When testing the durability upon extended load cycling (0.6–1.0 V), Pt3Ni aerogel demonstrates less stability than Pt/C which is related to the severe Ni leaching from the alloy under such conditions. These findings highlight the advantages of using unsupported ORR catalysts in PEFCs and point to the reduction of non-noble metal dissolution as the next development step.
Highlights
At present, few groups have reported promising durability in Polymer electrolyte fuel cells (PEFCs) for spray-coated membrane electrode assemblies (MEAs) prepared from unsupported catalysts
In a recent report we have demonstrated how the increase of porosity in the catalyst layer (CL) of Pt3Ni aerogel MEAs caused by the addition
In summary, we have investigated the behavior of unsupported Pt3Ni aerogel cathodes under start-stop and load-cycle accelerated stress tests (ASTs) in the Downloaded on 2019-08-22 to IP 152.88.42.51 address
Summary
Few groups have reported promising durability in PEFCs for spray-coated membrane electrode assemblies (MEAs) prepared from unsupported catalysts.
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