Copper oxide electrodeposition onto aluminium substrate exploration: new insights in the copper oxide electrodeposition from ionic liquids and deep eutectic solvents

In this article, we have reported the electrochemical deposition behaviour of copper and copper oxides on aluminium substrate from ionic liquids (ILs) and for the first time from deep eutectic solvents (DESs) based lithium. The electrodeposition tests were performed using pyrrolidinium acetate ([pyrr][CH3COO]) and pyrrolidinium hydrogen sulphate ([Pyrr][HSO4]) ILs and two DES based on N-methylacetamide (NMA) and lithium salt LiX imide (X = bis [(trifluoromethyl) sulphonyl] imide (TFSI) and nitrate (NO3)). The electrochemical behaviour of copper and copper oxides were investigated by cyclic sweep voltammetries. All the experimental tests were carried out at 50 degrees C and a concentration of 0.02 M of copper acetate. The related samples were analysed by scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction and Raman spectroscopy. The experimental results showed that the copper can be electrochemically reduced in solid state in either Ls or DES. For IL of [Pyrr][HSO4], structural characterization showed the formation of CuO films as an effect of annealing (in air at 600 degrees C for 30 min). In the deep eutectic melt, a mechanism for this reduction process has been proposed based on the formation of unstable copper oxide.