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

The reduction of Ag+ to Ag0 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 Ag0 nanoparticles by moieties present in the ‘distillable’ room temperature ionic liquid, DIMCARB (synthesised from Me2NH and CO2 in a 1.8:1 ratio) which is defined by the following equilibria: CO2 + Me2NH ↔ Me2NHCOOH + Me2NH ↔ [Me2NH2]+[Me2NCOO]−. At short reaction times in DIMCARB and when the contribution of the chemical reaction is small, Ag+ is electrochemically reduced to Ag0 and deposited onto a glassy carbon electrode via a progressive nucleation and growth mechanism. At long reaction times, when Ag0 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 Ag0 but is estimated to lie in the range of 2.1–3.0 × 10−7 cm2 s−1.