Demonstration of Feasibility Using Ionic Liquid as Electrolyte for Electrochemical Deposition and Recovery of Silver from Silver Oxide

Abstract

Silver oxide (Ag₂O) is soluble in the hydrophobic protic amide-type ionic liquid (IL), protonated-betaine bis((trifluoromethyl)sulfonyl)amide ([Hbet][TFSA]). Cyclic voltammetric behavior of Ag(I) showed a single redox couple, and NMR spectra implied that Ag⁺ might be coordinated with the [TFSA] anions in more extent than with the deprotonated [Hbet] ions (i.e. [bet]; a Zwitterion). By changing the scan rates and cycle numbers of potential scan utilized for the cyclic voltammetric electrodeposition, different particle sizes and distribution densities of silver nanoparticles (AgNPs) could be electrodeposited on glassy carbon disc electrode (GCE), which showed activities towards the electrochemical reduction of nitrate and oxidation of hydrazine, respectively, in alkaline solutions. The high faradic efficiencies (F.E.) of Ag electrodeposition using the contents of Ag₂O coin batteries as the Ag source implied that it may be possible to develop a process for recovering Ag from spent Ag₂O coin batteries based on the electrochemical system reported here.