Voltammetric Sizing of Inert Particles

Abstract

The average size of inert particles is determined using a simple electrochemical procedure. Alumina particles are deposited on an edge-plane graphite electrode, and a cyclic voltammogram is recorded. The scan rate employed varies between 0.2 and 2 V s(-1). At these scan rates the diffusion layer thickness is greater than the size of the alumina particles, minimizing the influence of the particles' height on the observed voltammetry. The average size of the particles is determined via comparison of the experimental voltammograms with simulations.

Fabrication of Random Assemblies of Metal Nanobands: A General Method

“…At 1 Vs À1 , the diffusion-layer thickness at the peak potential of the forward scan will be approximately 15 mm. [14] It can be seen from Figure 2 c that the spacing between the bands is less than 1 mm; therefore, the observed response obtained in Figure 6 is as expected. The fact that the nanoband array with a coverage V of approximately 0.9 gives a response almost equal in magnitude to that of the naked electrode indicates that the mass transport to the nanobands must be considerably faster than to the naked electrode.…”

In Situ Detection of Particle Aggregation on Electrode Surfaces

“…[5] found that particles on asurfacemight be reasonably approximateda sf lat discs, as compared to the diffusion layer thickness, the "height"o faparticle is small. The cylindricalu nit cell may therefore be modelled using cylindrical polar coordinates as shown in Figure 2.…”

“…[5] Aggregation of (nano)particles upon surface immobilization, especially during the most convenient technique of drop casting, is not only disadvantageous for most electrochemical applications,b ut identifying/quantifying the extent of aggregation is crucial to understand and correctly interpret the electrochemicalr esponse of such electrodes. An in situ approach to sizing such aggregates would be advantageous as it allows for af ast, reliable and inexpensive screening of different nanoparticle modification techniques for any electrode/nanoparticle system of interest.…”

“…[5] Notably,t hese cyclic voltammetry approaches require the electrode kineticst ob e known and sufficiently fast in order to access the size of the blockingf eatures. It has been pointedo ut recently, [7] that such assumptionsm ay cause significant errors and shall therefore best be avoided.…”

“…[4b, 5,6] It has been found that the associated apparent decrease in the electrochemical rate constanto f ar edox process, for instancet he oxidation of hexacyanoferrate (II) to hexacyanoferrate (III), can be used to determine the surface coverage of the electrode [4f] and under certain constraints, even the size of the blocking features. [5] Notably,t hese cyclic voltammetry approaches require the electrode kineticst ob e known and sufficiently fast in order to access the size of the blockingf eatures.…”