Modeling Interfacial Electron Transfer in the Double Layer: The Interplay between Electrode Coupling and Electrostatic Driving

Abstract

In this manuscript we present a theoretical model for studying the population dynamics of electrochemical systems within the region of the electrical double layer. We formulate this model in a coordinate system that separately resolves both the transport of redox species in the direction perpendicular to the electrode surface and the thermal fluctuations of the solvent environment that drive electron transfer. This formulation enables us to explore how the observable characteristics of electrochemical systems are influenced by spatial variations in the electric fields and electronic couplings that are inherent to the double-layer. We apply this model to highlight the fundamental interplay between two physical attributes of interfacial electrochemistry: electrode coupling and electrostatic driving. Using a simple model system we demonstrate how variations in the location of electron transfer can lead to systematic changes to the electrochemical transfer coefficient. We also illustrate that for certain redox reactions, differences in electrostatic driving between products and reactants can lead to non-monotonic current voltage behavior.

Theory of Coupled Ion-Electron Transfer Kinetics in Ion Intercalation Materials

“…5(c). Our analysis reveals a different mechanism that recovers Butler-Volmer kinetics via coupled ion-electron transfer, and is in agreement with Fokker-Planck approaches commonly used in the field of quantum chemistry [72,89].…”

“…Another example is that of non-adsorbing RedOx reactions near the electrodes. In that case, the ions have to work against the formed double layer to reach the electrified interface, where along their way an electron is transferred to the ion which consequently moves back to the solution [52,[70][71][72]. In both examples, the concerted nature of the process translates into a multidimensional energy landscape in the reaction coordinates [70,73], similar to that shown in Figs.…”

“…In the limiting case of κ/∆E IT 1, which can be due to steep changes in the electrostatic potential nearby the electrode, e.g. diffuse double layers [72,87,88], the analysis shows an interesting connection between coupled ionelectron transfer and Butler-Volmer kinetics [18,20,21]. Under these conditions, we consider the dependence of f O and f R to be linear in the ionic coordinate ξ leading to the following expressions for the RedOx species chemical potentials…”

Bayesian data analysis reveals no preference for cardinal Tafel slopes in CO2 reduction electrocatalysis

“…First, we consider the possibility that the symmetry coefficient α ≠ 1/2. Such deviations could arise, for example, due to disparate local slopes of the Marcus free energy surfaces at their crossing point, or reactant species position fluctuations in the electrochemical double layer [32][33][34][35] . Second, we examine the effect of partial charge transfer or surface dipole formation in the adsorption of CO 2 to the electrode surface, phenomena that have been hypothesized and characterized in prior studies on CO 2 reduction 29,36 .…”

A Grid-free Approach for Simulating Sweep and Cyclic Voltammetry

“…8 below), ET effects are incorporated through either a source term in the PDE or electrode boundary conditions. This approach has wide spread applicability and can be adadpted to take into account electrical double layer (EDL) effects (which are also called Frumkin corrections to the rate constant that account for uncompensated resistance due to field drop at the point/plane of ET) 5,6 , surface adsorption of a species pre-ET 7-10 , coupled homogenous chemical reactions [11][12][13] , and many other effects as well. Some of the relevant PDEs can be solved analytically if the ET kinetics are considered to be infinitely fast (i.e.…”