Electrochemical Behavior of Copper in 1-Butyl-3-Methylimidazolium Bromide-Copper(II) Bromide Binary Ionic Liquid

摘要

The methods of potentiometry, voltammetry, and gravimetry are used to study the electrochemical behavior of copper in the BMImBr-CuBr_2 ionic liquid (0-30.5 mol % CuBr_2). It is shown that electrochemical reduction of copper(II) occurs irreversibly, in two one-electron stages (transfer coefficient α 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) cm~2 s~(-1) in melts with the CuBr_2 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 CuBr_2 concentration in the binary melt and is comparable with that in aqueous solutions of H_2SO_4-CuSO_4.