(509as) Characterizing Electrochemical Systems By Volterra Kernel Analysis of Response to Small-Amplitude Oscillatory Voltage Inputs

Cyclic voltammetry (CV), a workhorse tool of electrochemical characterization, subjects an electrochemical system to a large amplitude triangular wave voltage signal. The nonlinear response characteristics of several electrochemical systems to such an input are well-understood, and features of the observed current waves (peak height, peak position, etc.) are used to intuit the microscopic parameters (rate constants, equilibrium potentials) of the underlying system. However, subjecting an electrochemical system to a large potential input has drawbacks: effects like competing reactions, capacitative charging responses, etc. can complicate the interpretation of CV response. Here, we develop a different paradigm, where an electrochemical system is subjected to a small amplitude (10-25 mV) oscillating voltage input around an arbitrary resting potential. The current response can be analyzed systematically using a Volterra series formalism, which enables more accurate parameter regression and model selection.