Square wave anodic stripping voltammetry at mercury-plated electrode. Simulation of surface morphology effects on electrochemically reversible, irreversible, and quasi-reversible processes: Comparison of thin films and microdroplets

Mercury electroplated onto solid electrodes is widely used for electrochemi cal measurements. Depending on the substrate, the coating can take the form of either a uniform thin film or an assembly of microdroplets. It is inter esting to ask the extent to which the morphological state can influence the nature of voltammetric responses from such electrodes. Accordingly, a gene ral approach is developed for the numerical simulation of square wave anodi c stripping voltammetry at hemispherical and uniform planar electrodes base d on the backward implicit method. This is applied to the modeling of elect rochemically reversible, irreversible, and quasi-reversible redox couples. Data from the simulations are validated by comparison of characteristic pro perties of the voltammograms with published work for the reversible limit o f the planar electrode. The variation of these characteristic features with electrode geometry and electrode kinetics is studied, and a comparison bet ween the planar and hemispherical geometry made. Last, experimental data is presented for the nature of mercury on the surface of both iridium and cop per substrates, obtained by atomic force microscopy.