Electrolysis of solid copper oxide to copper in Choline chloride-EG eutectic melt

Electrochemical deoxygenation of porous CuO pellet to prepare copper was investigated in the 33.3-66.7 mol% Choline chloride (ChCl)-EG eutectic melt at 353 K. Cyclic voltammetry of the Pt-powder cavity microelectrode loaded with CuO powder exhibited that the solid CuO can be electrochemically reduced in solid state in the eutectic melt. Constant-voltage (2.0 to 2.4 V) electrolysis, with an assembled cathode of a sintered porous CuO pellet and a graphite anode, that performed in the eutectic melt demonstrated the conversion process of oxide-to metal as confirmed by scanning electron microscopy, energy-dispersive X-ray, and X-ray diffraction spectra. A mechanism for this reduction process has been proposed on the basis of the in situ formation of numerous gas at the cathode, emphasizing that the oxidation of cathodically generated O2− ions occurred nearby along with the copper electroreduction, in which the new formed metal was served as a temporary anode, oxygen was generated at the interface of the reduced copper and electrolyte inside the cathode.