Effect of water on the electrodeposition of copper from a deep eutectic solvent

Valverde, P. E. and Green, T. A. and Roy, S. (2020) Effect of water on the electrodeposition of copper from a deep eutectic solvent. Journal of Applied Electrochemistry, 50 (6). pp. 699-712. ISSN 0021-891X

[img] Text (Valverde-etal-JAE-2020-Effect-of-water-on-the-electrodeposition-of-copper)
Valverde_etal_JAE_2020_Effect_of_water_on_the_electrodeposition_of_copper.pdf
Accepted Author Manuscript
Restricted to Repository staff only until 9 March 2021.

Download (810kB) | Request a copy from the Strathclyde author

    Abstract

    This study has examined the effect of water on the electrodeposition of copper from a deep eutectic solvent (DES). Initial physiochemical measurements showed that the viscosity and resistivity of the DES decreased with added water in the range 1 - 15 wt%. This reduction in viscosity resulted in an increase in the mass transfer limiting current, without narrowing the electrochemical window or altering the speciation of the copper chloro-complexes. This shows that metal deposition rates can be increased by water additions. The effect of water on the electrochemical kinetics of the Cu(I) and Cu(II) chloro-complexes was also studied. It was found that the kinetics of the Cu(I)/Cu(0) reaction is largely irreversible, while the Cu(II)/Cu(I) couple was quasi-reversible. The rate constants for Cu(II)/Cu(I) and Cu(I)/Cu(0) reactions were accelerated by water additions, although the transfer coefficients remained unchanged. The effect of increased deposition rates, electrolyte conductivity and reaction kinetics on deposit uniformity was estimated and subsequently verified by experiments. It was found that, although higher deposition rates could be achieved, the thickness of the deposit was non-uniform since the Wagner numbers remained relatively low.