Theory of anodic stripping voltammetry at wall-jet electrodes. Simulation of spatially differential stripping and redeposition phenomena

摘要

Numerical simulations based on the time dependent backward implicit method are used to develop the theory of anodic stripping voltammetry carried out under hydrodynamic conditions using mercury thin film wall-jet electrodes. The peak shape is shown to be highly sensitive both to electrolyte flow rate and to the potential sweep rate. The simulations permit visualization of concentrations both in solution and in the film throughout the voltammetric potential sweep. They reveal the film to be stripped in a spatially nonuniform fashion with the flow inducing the center of the electrode to be depleted before, and at less positive potentials than, the radial extremities of the electrode. Moreover for electrochemically reversible systems with flow and sweep rate parameters similar to those employed in analytical practice it is seen that material oxidized from the electrode center can become redeposited at radial distances closer to the electrode edge where the diffusion layer is thicker, before being re-oxidized later on in the potential sweep at more positive potentials.