Electrochemical behavior of copper in 1-butyl-3-methylimidazolium bromide-copper(II) bromide binary ionic liquid

The methods of potentiometry, voltammetry, and gravimetry are used to study the electrochemical behavior of copper in the BMImBr-CuBr₂ ionic liquid (0?C30.5 mol % CuBr₂). It is shown that electrochemical reduction of copper(II) occurs irreversibly, in two one-electron stages (transfer coefficient ?? of the cathodic process are 0.58 and 0.46, accordingly, for the first and second stages). Diffusion coefficients of copper-containing ions D _Cu(II) at 60°C are 1.3 × 10^?7 and 1.6 × 10^?7 cm² s^?1 in melts with the CuBr₂ concentration of 0.1 and 1.5 mol kg^?1 of BMImBr, accordingly. High (up to 98%) deposition efficiency and high-quality copper deposit can be obtained in the potential range of ?2.0 to ?1.8 V (vs. a platinum quasireference electrode). It is found that the copper corrosion rate grows at an increase in the CuBr₂ concentration in the binary melt and is comparable with that in aqueous solutions of H₂SO₄-CuSO₄.