Effect of KBr on electrodeposition of Ag in choline chloride-ethylene glycol deep eutectic solvents

Bright silver coatings were successfully prepared in deep eutectic solvent (DES) using the additive KBr in choline chloride-ethylene glycol (ChCl-EG, molar ratio 1:2). The results show that the reductive peak potential of the silver coordination ions shifts negatively with increasing KBr concentration. Relevant electrochemical parameters were calculated, such as the transfer coefficient & alpha; = 0.258 and the diffusion coefficient D = 1.04x10(-6) cm(2)& BULL;s(-1). The effects of temperature were investigated for the electron transfer activation energy E-A=23.144 KJ & BULL;mol(-1) and the diffusion activation energy E-D=42.281 KJ & BULL;mol(-1). The adsorption of bromine ions on the electrode surface was demonstrated using the impedance potential method and the impedance frequency method to derive differential capacitance curves. Simulation results from Material Studio software confirmed that bromine ions are mainly adsorbed on the hollow (fcc) sites on the crystalline surface of the copper electrode (100). The addition of KBr causes changes in the microstructure of the silver coating.