Rare and costly platinum-group metals are used for the demanding oxygen reduction reaction in hydrogen fuel Researchers examine a sample catalyst. Source: ANLResearchers examine a sample catalyst. Source: ANLcells. Efforts to reduce the amount of platinum consumed and thereby lower system cost have created nanoparticles with earth-abundant metals to increase their activity and surface area. Another approach replaces the platinum with metals such as cobalt and organics in the form of quinones.

A new highly active and stable electrocatalyst prepared by researchers from the U.S. Department of Energy’s Argonne National Laboratory (ANL) contains an ultralow-loading platinum content. The synthesis method uses cobalt or bimetallic cobalt and zinc zeolitic imidazolate frameworks as precursors.

A cobalt metal-organic framework compound was thermally activated to create oxygen reduction reaction-active cobalt sites. This material served as a substrate for the growth of cobalt-platinum alloy nanoparticle cores coated with thin platinum layers to form a core-shell structure.

The resulting durable catalyst consumes only about a quarter as much platinum as current technology. Two catalysts tested retained 64% and 15% of initial activity values after 30,000 voltage cycles in a fuel cell.

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