The effect of near wall hindered diffusion on nanoparticle-electrode impacts: A computational model

The influence of near wall hindered diffusion of nanoparticles on anodic particle coulometry (APC) is investigated. In an APC experiment, an electrode in a solution of nanoparticles is subject to a potential step from a value where no oxidation of nanoparticles occurs, to one where oxidative dissolution of nanoparticles is transport controlled. Nanoparticle-electrode impacts are then observed as spikes in the measured current. The area under these spikes corresponds to the charge transferred during the nanoparticle oxidation. A computational model is developed to simulate APC experiments, including the effect of near wall hindered diffusion. It is shown that this new, more complete picture is able to successfully simulate the experimental APC of nickel nanoparticles. It is also shown that a detailed, quantum mechanical tunnelling model is not required to describe the destructive oxidation of nanoparticles; an alternative simple impact model can successfully simulate experimental data.