Translating Fundamental Insights into Ag-Based Bimetallic Electrocatalysts to Anion-Exchange Membrane Fuel Cells

To address the challenges of high costs and scalability for fuel cells, it is essential to develop affordable and earth-abundant materials that are Pt-group-metal (PGM)-free. Recent advancements in PGM-free electrocatalysis for the oxygen reduction reaction (ORR) in alkaline media show that high catalyst loadings are needed to achieve high reaction rates; however, there are associated mass transport limitations. To address this issue, we developed low-loading ionomerless Ag-bimetallic thin films by alloying with 3d block elements or Sn. We bridge knowledge from fundamental rotating disk electrode (RDE) studies to gas-diffusion cathodes in high-temperature anion-exchange membrane fuel cells (HT-AEMFCs), resulting in high-activity ORR catalysis and peak power densities up to 1.2 W cm–2geo for the Ag-Sn and Ag-Co alloys. Experimental postcharacterization and theoretical calculations reveal small Co or Sn oxide nanoislands on Ag as likely active sites enhancing ORR activity, ultimately offering these low-loading PGM-free ORR materials as a viable path toward sustainable energy conversion.