Electrochemical cell design for the impedance studies of chlorine evolution at DSA® anodes

Abstract

A new electrochemical cell design suitable for the electrochemical impedance spectroscopy (EIS)studies of chlorine evolution on Dimensionally Stable Anodes (DSA®) has been developed. Despitebeing considered a powerful tool, EIS has rarely been used to study the kinetics of chlorine evolutionat DSA anodes. Cell designs in the open literature are unsuitable for the EIS analysis at high DSAanode current densities for chlorine evolution because they allow gas accumulation at the electrodesurface. Using the new cell, the impedance spectra of the DSA anode during chlorine evolution at highsodium chloride concentration (5 mol dm−3 NaCl) and high current densities (up to 140 mA cm−2)were recorded. Additionally, polarization curves and voltammograms were obtained showing little orno noise. EIS and polarization curves evidence the role of the adsorption step in the chlorine evolutionreaction, compatible with the Volmer-Heyrovsky and Volmer-Tafel mechanisms.