Dynamic\nSurface Dealloying for Pt<sub>3</sub>Co/C\nCatalysts with a Pt-Enriched Surface for the Oxygen Reduction Reaction

Pt-based\nalloys are important catalysts in fuel cells, especially\nfor the oxygen reduction reaction (ORR). A key problem to be addressed\nis to develop high-activity ORR catalysts with low Pt loading or,\nequivalently, to increase the catalytic activity per Pt amount. Here,\nwe report a Pt–Co alloy catalyst with Pt-enriched skin and\na Pt–Co core structure via microwave activation and ethylene\nglycol reduction. The synthesis route is efficient and controllable,\nresulting in highly active catalysts with a fine particle size and\nnarrow size distribution. The synthesized catalysts show significant\nadvantages in ORR activity compared to commercial catalysts. We proposed\nthat the improved activity and stability are due to a Pt-enriched\nsurface of the Pt<sub>3</sub>Co catalysts, and such a surface structure\nis dynamically formed via selective etching of Co during nonequilibrium\nsynthesis under the harsh environment of acid, ethylene glycol reduction,\nand microwave treatment.