A Dynamic Transmission Line Model to Describe the Potential Dependence of Double-Layer Capacitances in Cyclic Voltammetry

The intrinsic potential dependence of double-layer capacitances contributes to every cyclic voltammetry (CV) measurement. This study presents a dynamic transmission line model to describe the potential dependence of double layers in CV, exemplified and parameterized for a polished gold electrode. In detail, impedance spectra are measured under an incremental potential variation, from which a potential-dependent parameterization of the double layer in the form of constant phase elements in the frequency domain is derived. This parameterization is used to generate a dynamic potential-dependent transmission line network, in which the current response to potential variations is calculated on the basis of differential equations in the time domain. This approach adequately describes the impact of the potential on the double layer response of the gold electrode during CV. The presented model is discussed to represent the ion transport in the double layer directly by its physical interpretation as a dynamic transmission line, building an illustrative bridge between the physicochemical double-layer dynamics of real systems and the model world.