## 3 Results and Discussion
However, when 20.8 M of water was added, the viscosity of MSA was affected by the viscosity of water. For this reason, the viscosity is considered to decrease sharply. Figure 1: Cyclic voltammetry curves depending on the concentration of the added water: (**a**) 0 M, (**b**) 1.1 M, (**c**) 5.0 M, (**d**) 9.3 M, and (**e**) 20.8 M.  
Figure 2: Diffusion coefficient depending on the concentration of the added water. Figure 4 shows the large-scale cathodic and anodic potentiodynamic polarization curves recorded in the MSA electrolyte, according to the concentration of the added water for the recovery of Ag. The measured voltages in the cathodic and anodic branches tend to decrease due to an increase in the concentration of the added water. This trend could be associated with the change in the Ag ion mobility in the viscous electrolyte solution with the added water. The change in the cathodic and anodic branches indicates a reduction in the resistance during the electrochemical process. This phenomenon indicates the positive effect of adding water to the MSA electrolyte because of the increase in the cathodic efficiency. Figure 4 shows that the cathodic efficiencies improved under all experimental conditions. Particularly, the cathodic efficiency significantly improved when 20.8 M of water was added. This phenomenon is attributed to the increased mass transport of Ag ions to the electrode surface, which is advantageous for improving the cathodic efficiency [24]. As mentioned above, this indicates that a lower viscosity facilitates Ag ion transport in the electrolyte. As the viscosity of the electrolyte decreases, the ion diffusion increases, and the cathode efficiency becomes higher. Figure 5 shows the morphologies of the Ag deposits obtained at different concentrations of the added water in the electrospinning process. Branch-shaped electrodeposits were formed in the electrospinning process at an applied current density of 76.9 mA cm\({}^{-2}\). The size of the deposits decreased gradually with an increase in the concentration of the added water. In addition, the morphologies of the deposited Ag changed to a more dendritic shape. This phenomenon can be explained in terms of the ion mobility: with a decrease in the solution viscosity, the resistance of the solution to Ag ion mobility decreases; hence, the ion mobility and, consequently, acceleration of the rate of reaction, with the concentration of the added water, increases [25]. In general, structures with  
Figure 4: Dependence of the polarization curves on the concentration of the added water: (a) 0 M, (b) 1.1 M, (c) 5.0 M, (d) 9.3 M, and (e) 20.8 M.  
Figure 3: Variation in the viscosity of the MSA solution as a function of the concentration of added water: (a) 0 M, (b) 1.1 M, (c) 5.0 M, (d) 9.3 M, and (e) 20.8 M.  
dendritic morphologies can grow in an electrolyte with a non-uniform ion concentration. Migration, diffusion, and convection affect the ion transport in an electrolyte [26]. As shown, the Ag ion concentration gradient in Figure 5c is higher than those in Figure 5a,b in an electric field because of the higher Ag ion mobility, which leads to dendritic growth. Therefore, the morphology of the deposited Ag changed to a more dendritic shape with an increase in the concentration of the added water, as predicted in Figure 5, due to an increase in the ion mobility. It is also observed that the decrease in the particle size is related to the concentration of the added water. The particle size of the deposited powder is dependent on the concentration of the electrolyte, and it was found to decrease with an increase in the electrolyte concentration [27]. Since the mobility of Ag ions increases as the concentration of the added water increases, it is expected to have the same effect as that of a high Ag concentration. The typical XRD profile of the electrodeposited Ag shows only Ag diffraction peaks (Figure 6), indicating that the purity of the deposited Ag is sufficiently high.