Hydrodynamic voltammetry at membrane-covered electrodes

The modification of platinum electrodes with commercial filtration membranes is used to study the interplay between solution and membrane mass-transport in non-aqueous solution. Two types of commercial membrane, “track-etched” polyethylene terephthalate and γ-Al2O3, are employed. Voltammetric and amperometric data is obtained under both hydrodynamic (rotating-disc) and stationary conditions, which is interpreted in terms of a pinhole model. Contrasting behaviour is seen for the different membranes, which can be understood by consideration of the membrane thickness relative to the diffusion layer established in solution. In particular, overlapping diffusion behaviour is observed for the much thinner polymer membranes under hydrodynamic conditions.