Diffusional Cyclic Voltammetry at Electrodes Modified with Random Distributions of Electrocatalytic Nanoparticles: Theory

Electrodes modified by electrocatalytic nanoparticles find increasing application in electroanalysis and energy conversion. With the correct choice of nanoparticle material, oxidation or reduction can be brought about via an electrocatalytic process at the nanoparticle. Cyclic voltammetry is studied at such electrodes for the case of a simple homogeneous one-electron reduction involving solution-phase species (A + e− ⇌ B). Numerical simulations are used to identify how the voltammetric features are influenced by the electrochemical rate constant of the electron transfer between the A/B couple and the nanoparticle, the surface coverage of nanoparticles, and the voltage scan rate. Data are included in the Supporting Information to enable determination of the surface coverage from experimental data and to discern the onset of diffusion layer overlap for a range of experimental situations. Lastly, the minimum extent of surface modification required to confer upon the electrode a bulk geometric response corresponding to that of the electrocatalytic process is estimated.