Electrodeposition of lead on glassy carbon and mercury film electrodes from a distillable room temperature ionic liquid,DIMCARB

The electrochemical reduction of Pb²⁺ has been studied in the ‘distillable’ ionic liquid DIMCARB (a mixture of adducts of dimethylamine and carbon dioxide, comprising both neutral and ionic moieties). Voltammetric results show that Pb²⁺ is reduced in a single step to form Pb metal via a nucleation and growth mechanism on a glassy carbon electrode. Ex situ powder X-ray diffraction studies on deposited lead show the presence of both α- and β-PbO₂, as well as elemental lead, suggesting the finely deposited lead particles are in an active rather than passive state. Chronamperometric and scanning electron microscope measurements show that the nucleation and growth follows a progressive nucleation mechanism on glassy carbon. Large peak–peak separations for the Pb reduction and oxidation are consistent with this mechanism and do not suggest electrochemical reversibility. However, experiments with co-deposition of Hg show that this irreversibility is a result of deposition onto a solid glassy carbon surface rather than a solvent effect. The diffusion coefficient of Pb²⁺ in DIMCARB has been calculated to be 1.8±0.4×10⁻⁷ cm² s⁻¹. Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users. This work is dedicated to Piero Zanello on the occasion of his 65th birthday in recognition of his numerous contributions to inorganic electrochemistry.