Pt-Au-Co Alloy Electrocatalysts Demonstrating Enhanced Activity and Durability toward the Oxygen Reduction Reaction

Here we investigate the oxygen reduction reaction electrocatalytic activity and the corrosion stability of several ternary Pt-Au-Co and Pt-Ir-Co alloys, with Pt-Au-Co having never been previously studied for ORR. The addition of Au fine tunes the lattice parameter and the surface electronic structure to enable activity and cycling stability that is unachievable in Pt-25 atom % Co (state-of-the-art binary baseline). The ternary alloys exhibit a volcano-type dependence of catalytic efficacy on the content of Au or Ir. Pt-2.5 atom % Au-25 atom % Co alloy shows a specific activity of 1.41 mA cm-2 at 0.95 V, which is 16% and 404% higher than those of identically synthesized Pt-Co and pure Pt, respectively. This enhancement is promising in comparison to a range of previously published Pt skeleton and Pt skin alloys and is in fact the most optimum reported for a skeleton-type system. The catalysts exhibit dramatically improved corrosion stability with increasing levels of Au or Ir substitution, with the specific activity of all the ternary alloys being superior to that of Pt-Co after 100,000 potential cycles of 0.6-1.0 V. For instance, postcycled Pt-10 atom % Au-25 atom % Co shows a specific activity of 0.63 mA cm(-2), which is 140% higher than that of Pt-Co and 439% higher than that of Pt. HRTEM and XPS shows that Au alloying promotes the formation of an atomically thin Pt-Au-rich surface layer, which imparts kinetic stabilization against the dissolution of the less noble solute component.