Electrochemical Characterization of DSA®-Type Electrodes Using Niobium Substrate

Abstract

This paper describes the electrochemical characterization of DSA®-type electrodes using niobium substrate, and the results were compared with traditional DSA®-type oxide electrodes, i.e., using titanium substrate. The surface morphology, electrocatalytic activity, and stability of the coating were investigated by scanning electron microscopy, energy dispersive X-ray spectrometry, cyclic voltammetry, electrochemical impedance spectroscopy (EIS), and lifetime tests. EIS measurements were recorded at a constant potential between 0.2 and 1.0 V vs Ag/AgCl, in the frequency range of 5 mHz to 100 kHz, using the “single sine” method and a sine wave amplitude of 5 mV (p/p). After testing a number of different equivalent circuits, we found that the whole set of data in the double layer domain of the electrodes can be fitted by assuming the circuits Rs(CPEfRf)(CdlRct), Rs(CPEfRf)(CPEdlRct), and RsCPEfG(CPEdlRct). The results suggest the formation of a less conducting film on the Nb substrate when compared to Ti substrate. The findings of this work, such as difficult adherence of coating on niobium, reduction of voltammetric charge, and short lifetime of electrodes prepared on Nb substrate, suggest that the substitution of titanium by niobium is unfeasible.