Pulse plating of copper from deep eutectic solvents

The effect of pulse parameters on the deposition of copper from a chloride-based deep eutectic solvent (DES) was investigated. While satisfactory deposits could be obtained for some pulse conditions, at small duty cycles or long off-times the current efficiencies obtained were very low. These findings were consistent with a corrosion process occurring during the off-time, most likely the comproportionation reaction: Cu + CuIICl4 2- → 2CuICl2 - . Initial experimental results were consistent with the corrosion rate being controlled by the transport of the CuIICl4 2- species to the electrode surface. With this assumption, a simple corrosion model was developed to account for the observed loss in current efficiency as a function of the pulse conditions. While this model broadly predicts the observed results some discrepancy between the observed and measured were noted.