Dynamic electrochemical impedance spectroscopy, for electrocatalytic reactions

Abstract

Dynamic electrochemical impedance spectroscopy with the ac signal applied while sweeping the potential is a powerful method to study reaction mechanisms of surface electrochemical reactions. The ability to reliably measure low frequencies while sweeping is key to its successful implementation. Numerical modeling of a simple adsorption reaction is used to decide how fast the potential sweep can be at a given frequency. Careful baseline subtraction is crucial to achieve accurate results. Hardware and software implementing this method are described. With attention to issues of resolution and using the baseline correction algorithm described, accurate results can be obtained down to about 1 Hz under practical conditions. Sample experimental data is validated using the Kramers-Kronig transform and a consistency test involving the voltammogram slope and the low frequency data.