Electrodeposition of silver from the ‘distillable’ ionic liquid, DIMCARB in the absence and presence of chemically induced nanoparticle formation

Abstract

The reduction of Ag + to Ag 0 has been studied electrochemically at glassy carbon electrodes using the techniques of cyclic voltammetry and chronoamperometry. Ag + is known to be chemically reduced to form Ag 0 nanoparticles by moieties present in the ‘distillable’ room temperature ionic liquid, DIMCARB (synthesised from Me 2NH and CO 2 in a 1.8:1 ratio) which is defined by the following equilibria: CO 2 + Me 2NH ↔ Me 2NHCOOH + Me 2NH ↔ [Me 2NH 2] +[Me 2NCOO] −. At short reaction times in DIMCARB and when the contribution of the chemical reaction is small, Ag + is electrochemically reduced to Ag 0 and deposited onto a glassy carbon electrode via a progressive nucleation and growth mechanism. At long reaction times, when Ag 0 nanoparticles are present and become attached to the glassy carbon surface, Ag + also is electrochemically reduced and deposited via a 2D–2D nucleation and growth mechanism onto Ag nanoparticles attached to the electrode surface. Images obtained during the course of the electrodeposition reaction by atomic force microscopy reveal that a compact film of Ag also is deposited onto glassy carbon in the presence of nanoparticles. Calculation of the diffusion coefficient of Ag + in DIMCARB is complicated by the chemical formation of Ag 0 but is estimated to lie in the range of 2.1–3.0 × 10 −7 cm 2 s −1.