An efficient approach to compartmentalize double layer effects on kinetics of interfacial proton-electron transfer reactions

Abstract

Activation barriers for elementary electrochemical reactions can show strong dependence on the composition and structure of the electrode–electrolyte interface, the electrochemical double layer (EDL), due to the highly polar nature of ion/electron transfer transition states. A compartmentalized analytical framework, built upon DFT calculations, is developed to consider complex interactions between reaction intermediates and the EDL. The approach analytically captures how altering interfacial properties, such as the dielectric constant or distribution of electrolyte charges, impact electrocatalytic activation barriers. Dipole moment changes along the reaction path plays the largest role in dictating the extent to which interfacial properties impact elementary electrochemical kinetics. The compartmentalization and uncertainty quantification capability of the developed framework is illustrated employing a Helmholtz model with two parameters, dielectric constant and double layer thickness. The framework translates routine DFT analysis of (water-assisted) hydrogenation activation barriers to proton-coupled electron transfer barriers that depend analytically on electrode potential and EDL properties.