An Interfacially Alloyed Pt⁁Ag Cathode Catalyst for the Electrochemical Reduction of Oxygen

An interfacially alloyed Pt-on-Ag nanostructure (Pt0.5⁁Ag-B, atomic Pt/Ag ratio being 0.5) was loaded on Vulcan XC-72 carbon to make a cathode Pt0.5⁁Ag-B/C catalyst for the oxygen reduction reaction (ORR). The electrocatalytic performance of this Pt0.5⁁Ag-B/C catalyst was measured by reference to its unalloyed counterpart Pt0.5⁁Ag-A/C and E-TEK Pt/C catalysts. The intrinsic activity of Pt in the Pt0.5⁁Ag-B/C catalyst was identified to be twice that in the E-TEK Pt/C catalyst although the half-wave potentials (E1/2) of the ORR curves over both catalysts were the same. Compared with the unalloyed Pt0.5⁁Ag-A/C catalyst, the alloying at the Pt/Ag interface in the Pt0.5⁁Ag-B/C catalyst gave a more positive E1/2 and also a significantly higher mass-specific activity of Pt for ORR.