## 3 Results and Discussion
### The Effect of Temperature  
Figure 1a exhibits the corresponding experiments in the IL, C4 mimCl; in other words, Cu electrochemical dissolution and the voltammetry of 0.1 M CuCl\({}_{2}\cdot\)2H\({}_{2}\)O on a Pt electrode. This experiment had to be performed at 70 \({}^{\circ}\)C owing to the high melting point of C4 mimCl. Clearly, it is seen that a comparable current density was observed for copper dissolution to that of choline chloride-based IL. Moreover, the same onset potential for electrochemical copper dissolution was also obtained. However, the most noticeable difference between the electrochemical dissolution responses in choline chloride-based IL and imidazolium-based IL is that there is no quasi-passivation response in the latter and there is an inflection point occurring the identical spatial as the Cu(I)/(II) process. It is also worth noting that the voltammogram for CuCl\({}_{2}\cdot\)2H\({}_{2}\)O in C4 mimCl is quite comparable to that in ethaline, showing two one-electron reductions and oxidation processes. Basically, the ligands for copper's dissolution electrochemically, should be the same in both liquids (Cl\({}^{-}\)). However, there is a discrepancy in the electrochemical behaviour in both electrolytes, which can, therefore, only be due to kinetic factors (diffusion of copper from the electrode and Cl\({}^{-}\) to the electrode) or thermodynamic factors owing to the solubility of the chlorometallic complexes in the both electrolytes. From the literature survey, one can see a huge number of studies on copper dissolution and deposition in a various electrolyte solutions. The kinetics of the electrodeposition of a copper salt in choline chloride-based IL was studied, and it was determined that the Cu(I)/II process is quasi-reversible with a rate constant of \(9.5\pm 10^{-4}\) cm\(\cdot\)s\({}^{-1}\)[25]. For copper to be deposited from its salt in the electrolyte, the amount of copper deposited on the electrode's surface must be quite small so it can all be dissolved in the anodic sweep (returning the current to approximately zero), and a diffusion-limited current is seen for the oxidation of Cu(I) to Cu(II). When copper dissolution is conducted electrochemically at a bulk copper electrode, the copper is effectively at infinite concentration. The solution close to the electrode's surface, i.e., at the interface region, could become saturated. It is proposed that that is what occurred in Figure 1a at the potential about +0.2 V. Saturating the solution at the interfacial region with the copper complex will result in a decrease in the oxidative current as the electrode becomes blocked with dissolution product, and as a consequence, an asymmetric peak is gained. The number of moles involved in the phase transitions at first oxidation peaks have been computed and are presented in Table 1. One can conclude that copper's conversion from metallic copper to Cu(I) in Ethaline is about 90 times higher than stripping of electrodeposited copper one in choline chloride-based and imidazolium based electrolytes, using platinum as a substrate at 20 \({}^{\circ}\)C and 70 \({}^{\circ}\)C,  
Figure 4: UV-Vis spectra of a dissolved metallic copper disc (solid line) at 50 mA\(\cdot\)cm\({}^{-2}\) for 1 h at ambient temperature and 0.1 mM (CuCl\({}_{2}\))2H\({}_{2}\)O (dash line) in 1:2 EG:ChCl electrolyte (choline chloride-based IL) on a platinum electrode. respectively. The number of moles copper stripped electrochemically in the choline chloride-based IL at 20 \({}^{\circ}\)C is slightly lower than the moles calculated in the imidazolium based IL at 70 \({}^{\circ}\)C. This might be owing to higher viscosity of imidazolium-based IL even at 70 \({}^{\circ}\)C (142 cP) to choline chloride-based IL (36 cP) at 20 \({}^{\circ}\)C [26]. The quasi-passivation process in the electrochemical dissolution of bulk copper in choline based IL at 20 \({}^{\circ}\)C could be as a result of the low solubility of CuCl\({}_{2}\).