Hybrid Electrocatalyst Ag/Co/C via Flash Joule Heating for Oxygen Reduction Reaction in Alkaline Media

Abstract The commercial catalysts for oxygen reduction reaction (ORR) are highly dependent on the scarce and expensive Pt to achieve high activity and reasonable durability, especially for the fuel cells used in automobiles. Ag alloys have been proposed as promising candidates for non-Pt ORR catalysts in alkaline media, with reasonably high activity at significantly lower cost. Herein we demonstrate the synthesis of Ag/Co/C hybrid electrocatalyst for ORR via radiative flash Joule heating. Unlike the previously reported solid-solution structure of the quenched immiscible alloys by flash Joule heating, the large immiscibility gap in the liquid state of the Ag-Co alloy prevents the formation of solid solution. The hybrid catalyst exhibits a specific activity 40 times and a mass activity 52 times higher than that of the pristine Ag/C at 0.8 V vs. RHE in alkaline media, and its tolerance to methanol and ethanol is superior to that of commercial Pt/C. The enhanced activity and good stability are attributed to the enhanced oxygen adsorption energy on silver due to the strong interaction between silver and cobalt.