Au/Ta(110) and Au/Nb(110) as Highly Active, Stable, and Inexpensive Catalysts for Oxygen Reduction Reaction on Hydrogen Fuel Cell Cathodes: Prediction from First Principles

We propose here structures - a gold monolayer on early transition metal surfaces - as a promising alternative to the prohibitively expensive platinum-based electro-catalysts for the oxygen reduction reaction (ORR), which occurs on hydrogen fuel cell cathodes. Based on existing knowledge and educated guesses, we preselect Au/Nb, Au/Ta, Au/Mo, and Au/W as potential catalysts. Our calculations show that these materials are stable and have very high dissolution potentials. A deviation from the linear scaling for the binding energy of ORR intermediates, revealed for Au/Nb and Au/Ta, has a desired impact on the ORR thermodynamics. We find it to be a result of hybridization of p-electronic states of oxygen belonging the OOH-radical and Au-p(z) states. The calculated ORR free energy diagrams show that the ORR onset potentials for Au/Nb and Au/Ta are significantly higher than that for Pt. We thus predict two inexpensive, thermodynamically and electrochemically stable, and highly active ORR catalysts.