Experimental and Computational Evidence of Highly Active Fe Impurity Sites on the Surface of Oxidized Au for the Electrocatalytic Oxidation of Water in Basic Media

Abstract

AbstractAddition of Fe to Ni‐ and Co‐based (oxy)hydroxides has been shown to enhance the activity of these materials for electrochemical oxygen evolution. Here we show that Fe cations bound to the surface of oxidized Au exhibit enhanced oxygen evolution reaction (OER) activity. We find that the OER activity increases with increasing surface concentration of Fe. Density functional theory analysis of the OER energetics reveals that oxygen evolution over Fe cations bound to a hydroxyl‐terminated oxidized Au (Fe–Au2O3) occurs at an overpotential ∼0.3 V lower than over hydroxylated Au2O3(0.82 V). This finding agrees well with experimental observations and is a consequence of the more optimal binding energetics of OER reaction intermediates at Fe cations bound to the surface of Au2O3. These findings suggest that the enhanced OER activity reported recently upon low‐potential cycling of Au may be due to surface Fe impurities rather than to “superactive” AuIIIsurfaquo species.