Title: Electrodeposition of copper–zinc alloys from an ionic liquid-like choline acetate electrolyte
Authors: De Vreese, Peter
Skoczylas, Alicja
Matthijs, Edward ×
Fransaer, Jan
Binnemans, Koen #
Issue Date: 2013
Publisher: Elsevier
Series Title: Electrochimica Acta vol:108 pages:788-794
Abstract: The ionic liquid choline acetate was used as a cyanide-free electrolyte for the electrodeposition of copper–zinc alloy (alpha-brass) thin films on a steel substrate. In comparison with the more commonly used choline chloride based deep-eutectic solvents, choline acetate enables the electrodeposition in absence of chloride ions, in order to avoid their accelerating effect. With 0.1 mol dm−3 Cu(OAc)2·H2O and 0.1 mol dm−3 Zn(OAc)2·2H2O dissolved in choline acetate, the reduction potentials of copper and zinc were separated by 500 mV. Using potentiostatic deposition, only coatings of a negligible thickness could be obtained. Upon addition of triethanolamine, the deposition rates of both copper and zinc increased substantially and the reduction potential of copper shifted 300 mV toward more cathodic potentials.Bright layers with a thickness of up to 200 nm could be obtained. With a 1:2 molar ratio of metal-to-triethanolamine, well-adherent mirror-bright deposits with a composition of 90 wt% Cu and 10 wt% Zn were deposited at −1.5 V versus Ag|AgCl (3 M KCl), with a cathodic current efficiency of around 75%. For longer deposition times, morphological instabilities occurred. Addition of polyvinyl alcohol in concentrations between 8 and 20 mg dm−3 enabled the deposition of mirror-bright brass layers with a thickness up to 1 micrometer. Variation of the deposition potential between −1.3 and −1.5 V had no marked influence on the composition of the alloy. However, the cathodic current efficiency dropped to 25% when potentials more negative than −1.5 V were applied. A decrease in the copper concentration in the electrodeposition bath resulted in dark-red powdery deposits while an increase of the zinc concentration in the bath, resulted in mirror-bright, well-adherent brass layers, with a copper content as high as 90 wt%. SEM images showeda grain size of 150 nm. XRD analyses indicated that the depositions consisted only of alpha-brass.
ISSN: 0013-4686
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Molecular Design and Synthesis
Chemistry - miscellaneous
Surface and Interface Engineered Materials
KU Leuven, Technology Campuses Ghent and Aalst
× corresponding author
# (joint) last author

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