Anodic reactions and the corrosion of copper in deep eutectic solvents

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

An analysis of the anodic reaction occurring at soluble copper anodes during the electrodeposition of copper from an ethaline-based deep eutectic solvent (DES) has been performed. It was shown by UV-Vis spectroscopy and electrochemical measurements that the dominant anodic species produced is the CuCl2- complex. In pure ethaline the current efficiency of the anodic process is 100% and the dissolution valency is one. However, in the presence of Cu(II) species the apparent dissolution valency measured gravimetrically was typically less than unity, corresponding to an observed mass loss greater than that expected from Faraday’s law. Moreover, the apparent dissolution valency showed a marked dependence on the electrode rotation rate, Cu(II) concentration and the water content of the deep eutectic solvent. These observations were consistent with a corrosion reaction occurring in parallel with anodic dissolution. The most likely corrosion process is the comproportionation reaction: 2CuCl2-  CuCl42- + Cu. Voltammetric data indicate that the rate of this process is controlled by the mass transport of the CuCl42- complex to the surface and can readily explain the observed dissolution valency dependencies. Finally, it is noted that anomalous dissolution of Cu anodes in deep eutectic solvents makes their implementation as soluble anodes problematic.
LanguageEnglish
PagesD313-D320
Number of pages8
JournalJournal of the Electrochemical Society
Volume165
Issue number9
DOIs
Publication statusPublished - 30 May 2018

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eutectics
Eutectics
Copper
corrosion
dissolving
Dissolution
Corrosion
copper
Anodes
anodes
Ultraviolet spectroscopy
Electrodeposition
electrodeposition
Water content
moisture content
unity
Mass transfer
Electrodes
electrodes
spectroscopy

Keywords

  • soluble copper anodes
  • copper
  • deep eutectic solvent

Cite this

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title = "Anodic reactions and the corrosion of copper in deep eutectic solvents",
abstract = "An analysis of the anodic reaction occurring at soluble copper anodes during the electrodeposition of copper from an ethaline-based deep eutectic solvent (DES) has been performed. It was shown by UV-Vis spectroscopy and electrochemical measurements that the dominant anodic species produced is the CuCl2- complex. In pure ethaline the current efficiency of the anodic process is 100{\%} and the dissolution valency is one. However, in the presence of Cu(II) species the apparent dissolution valency measured gravimetrically was typically less than unity, corresponding to an observed mass loss greater than that expected from Faraday’s law. Moreover, the apparent dissolution valency showed a marked dependence on the electrode rotation rate, Cu(II) concentration and the water content of the deep eutectic solvent. These observations were consistent with a corrosion reaction occurring in parallel with anodic dissolution. The most likely corrosion process is the comproportionation reaction: 2CuCl2-  CuCl42- + Cu. Voltammetric data indicate that the rate of this process is controlled by the mass transport of the CuCl42- complex to the surface and can readily explain the observed dissolution valency dependencies. Finally, it is noted that anomalous dissolution of Cu anodes in deep eutectic solvents makes their implementation as soluble anodes problematic.",
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Anodic reactions and the corrosion of copper in deep eutectic solvents. / Green, T. A.; Valverde, P.; Roy, S.

In: Journal of the Electrochemical Society, Vol. 165, No. 9, 30.05.2018, p. D313-D320.

Research output: Contribution to journalArticle

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N2 - An analysis of the anodic reaction occurring at soluble copper anodes during the electrodeposition of copper from an ethaline-based deep eutectic solvent (DES) has been performed. It was shown by UV-Vis spectroscopy and electrochemical measurements that the dominant anodic species produced is the CuCl2- complex. In pure ethaline the current efficiency of the anodic process is 100% and the dissolution valency is one. However, in the presence of Cu(II) species the apparent dissolution valency measured gravimetrically was typically less than unity, corresponding to an observed mass loss greater than that expected from Faraday’s law. Moreover, the apparent dissolution valency showed a marked dependence on the electrode rotation rate, Cu(II) concentration and the water content of the deep eutectic solvent. These observations were consistent with a corrosion reaction occurring in parallel with anodic dissolution. The most likely corrosion process is the comproportionation reaction: 2CuCl2-  CuCl42- + Cu. Voltammetric data indicate that the rate of this process is controlled by the mass transport of the CuCl42- complex to the surface and can readily explain the observed dissolution valency dependencies. Finally, it is noted that anomalous dissolution of Cu anodes in deep eutectic solvents makes their implementation as soluble anodes problematic.

AB - An analysis of the anodic reaction occurring at soluble copper anodes during the electrodeposition of copper from an ethaline-based deep eutectic solvent (DES) has been performed. It was shown by UV-Vis spectroscopy and electrochemical measurements that the dominant anodic species produced is the CuCl2- complex. In pure ethaline the current efficiency of the anodic process is 100% and the dissolution valency is one. However, in the presence of Cu(II) species the apparent dissolution valency measured gravimetrically was typically less than unity, corresponding to an observed mass loss greater than that expected from Faraday’s law. Moreover, the apparent dissolution valency showed a marked dependence on the electrode rotation rate, Cu(II) concentration and the water content of the deep eutectic solvent. These observations were consistent with a corrosion reaction occurring in parallel with anodic dissolution. The most likely corrosion process is the comproportionation reaction: 2CuCl2-  CuCl42- + Cu. Voltammetric data indicate that the rate of this process is controlled by the mass transport of the CuCl42- complex to the surface and can readily explain the observed dissolution valency dependencies. Finally, it is noted that anomalous dissolution of Cu anodes in deep eutectic solvents makes their implementation as soluble anodes problematic.

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