title: Hampering of the Stability of Gold Electrodes by Ferri-/Ferrocyanide Redox Couple Electrolytes during Electrochemical Impedance Spectroscopy.
abstract: In the past decades, numerous measurements have applied electrochemical impedance spectroscopy (EIS) in an electrode-electrolyte system consisting of gold electrodes and the redox couple potassium ferrocyanide/potassium ferricyanide (HCF). Yet these measurements are often hampered by false positive and negative results. Electrochemical impedance signals often display a nonlinear drift in electrolyte systems containing the HCF redox couple, which can mask the accuracy of the analysis. Thus, this Article aims to elucidate the stability and reliability of this particular electrode-electrolyte system. Here, different gold electrode cleaning treatments were compared with respect to adsorption and roughness of the surface of gold electrodes. They show substantial nonlinear long-term drifts of the charge-transfer resistance RD. In particular, the use of HCF-containing electrolytes causes adsorption and corrosion on the gold electrode surface, resulting in a nonlinear impedance behavior that depends on the incubation period as well as on electrolyte composition. Consequently, it is strongly recommended not to use HCF containing electrolytes in combination with gold electrodes.
authors.affiliation: Institute of Materials in Electrical Engineering 1, RWTH Aachen University , Sommerfeldstrasse 24, 52074 Aachen, Germany.
authors.forename: Jaroslav
authors.initials: J
authors.lastname: Lazar
authors.affiliation: Institute of Materials in Electrical Engineering 1, RWTH Aachen University , Sommerfeldstrasse 24, 52074 Aachen, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Schnelting
authors.affiliation: Institute of Electrochemistry and Energy Systems, Bulgarian Academy of Sciences , Akad. G. Bonchev 10, 1113 Sofia, Bulgaria.
authors.forename: Evelina
authors.initials: E
authors.lastname: Slavcheva
authors.affiliation: Institute of Materials in Electrical Engineering 1, RWTH Aachen University , Sommerfeldstrasse 24, 52074 Aachen, Germany.
authors.forename: Uwe
authors.initials: U
authors.lastname: Schnakenberg