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

The reduction of Ag+ to Ag-0 has been studied electrochemically at glassy carbor 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 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 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 cf 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 x 10(-7) cm(2) s(-1). (C) 2008 Elsevier B.V. All rights reserved.