Universality in Oxygen Reduction Electrocatalysis on Metal Surfaces

In this work, we extend the activity volcano for oxygen reduction from the face-centered cubic (fcc) metal (111) facet to the (100) facet. Using density functional theory calculations, we show that the recent findings of constant scaling between OOH* and OH* holds on the fcc metal (100) facet, as well. Using this fact, we show the existence of a universal activity volcano to describe oxygen reduction electrocatalysis with a minimum overpotential, eta(min) = 0.37 +/- 0.1 V. Specifically, we find that the (100) facet of Pt is found to bind oxygen intermediates too strongly and is not active for oxygen reduction reaction (ORR). In contrast, Au(100) is predicted to be more active than Au(111) and comparable in activity to Pt alloys. Using this activity volcano, we further predict that Au alloys that bind OH more strongly could display improved ORR activity on the (100) facet. We carry out a computational search over candidate alloys and suggest that alloying Au with early transition metals could lead to materials that exhibit enhanced ORR activity. We also prescribe a simple principle in the choice of nanoparticle catalysts in which the chosen catalyst should have its dense facet on the weak binding leg of the volcano so that its more open facets and defects could also be active.