Unifying Kinetic and Thermodynamic Analysis of 2 e– and 4 e– Reduction of Oxygen on Metal Surfaces

Abstract

Oxygen electrochemistry has played a key role in developing the foundational understanding of surface electrocatalysis. In this work, we develop a detailed microkinetic model for the oxygen reduction reaction based on density functional theory calculations and molucular dynamics simulations. The developed microkinetic model has a reaction order of 1 in O2 and a 59 mV/dec Tafel slope in the potential range where the Pt(111) surface is dominated by OH adsorption. Using calculated scaling and Bronsted–Evans–Polanyi relations, we extend this analysis to calculate the activity on materials with a varying OH binding energy. We demonstrate the existence of a kinetic activity volcano which is in close agreement with the thermodynamic activity volcano derived earlier. Both of these analyses identify an activity optimum around 0.1 eV weaker binding of OH relative to Pt(111). The predictions of the kinetic activity volcano are in close agreement with several RDE experiments on metals and Pt alloys. On the basis of r...