Preparation of photoactive graphene oxide-Cu2O/Cu nanostructures by the electrochemical treatment of Cu-Ni leaching solutions using graphite electrodes

Sustainable and economic separation of Cu and Ni from their leaching solutions is a long-standing challenge. Here, the electrolysis of synthetic Cu-Ni leaching solutions is examined using graphite electrodes in order to continuous separation of these metals, and also the preparation of photoactive graphene oxide (GO)-Cu2O/Cu hybrid structures. The carbon materials produced were characterized by various techniques including X-ray diffraction, Raman, Fourier-transform infrared and ultraviolet-visible spectroscopy, as well as electron microscopy. The proposed electrochemical approach is based on the surface exfoliation of the graphite anode to form GO, and the copper deposition on the cathode, followed by the chemical formation of Cu2O anchored on the surface of GO flakes. The concentration of Cu2+ in the solution is found to gradually reduce from an initial value of 2.79 to 0.37 g/l during 5 h of electrolysis, while the Ni2+ concentration remains almost unchanged. Moreover, the hybrid structure produced is found to be effective for the degradation of methyl orange under natural indoor weak light irradiation, with high cycling stability. The mechanism involved in the process is discussed.