Ultralow-loading platinum-cobalt fuel cell catalysts derived from imidazolate frameworks.

Achieving high catalytic performance with the lowest amount of platinum is critical in fuel cell cost reduction. We describe a method of preparing highly active yet stable electrocatalysts containing ultralow Pt content using Co or Co/Zn zeolitic imidazolate frameworks as precursors. Synergistic catalysis between strained Pt-Co core-shell nanoparticles over a platinum-group-metal-free (PGM-free) catalytic substrate led to excellent fuel cell performance under 1 atmosphere of O2 or air at both high voltage and high current domains. Two catalysts achieved the oxygen reduction reaction (ORR) mass activities of 1.08 A mgPt -1 /1.77 A mgPt -1 and retained 64%/15% of initial values after 30,000 voltage cycles in fuel cell. Computational modeling reveals that the interaction between Pt-Co and PGM-free sites improves ORR activity and durability.