ELECTROCHEMISTRY OF COPPER IN A ROOM-TEMPERATURE ACIDIC CHLOROALUMINATE MELT

The electrochemical behavior of copper was investigated in the acidic, room temperature molten salt aluminum chloride-N-methylpyridinium chloride [6733 mole percent (m/o)] and compared to results previously obtained in inorganic chloroaluminate melts. Techniques used were stationary and rotating disk electrode voltammetry, chronoamperometry, controlled potential coulometry, and potentiometry. Copper (II), introduced into the melt as CuCl2, underwent two one-electron reduction steps. The first reduction step, Cu(II) + e- ⇌ Cu(i), was reversible at both glassy carbon and tungsten electrodes. The second reduction step, Cu(I) + e- ⇌ Cu, was controlled by rate of nucleation in the initial phase of deposit formation at these electrodes. The equilibrium constant for the reaction Cu(II) + Cu ⇌ 2Cu(I) was appreciably larger than that observed for this reaction in acidic, inorganic chloroaluminate melts. Standard potentials for the Cu(II)/Cu(I) and Cu(I)/Cu couples were determined. © 1979, The Electrochemical Society, Inc. All rights reserved.