The cyclic voltammetry response of partially blocked electrodes is modeled using finite difference simulations and a method presented for determining currents at electrode surfaces which have a well-defined geometric blocking pattern. Peak current and peak separation data are presented for six decades of scan rates, blocking coverage values between 0.1 and 0.9 and between the limits of reversible and irreversible electrochemistry. The validity of the simulation approach employed is verified by data obtained experimentally from purpose-built partially blocked gold film electrodes, with either a cubic or hexagonal geometric array of electroinactive disks uniformly distributed on the electrode surface. Comparison of theory with experiment suggests that the modeling of hexagonally distributed blocking systems is superior to that of the cubically arranged ones.

The cyclic voltammetric response of partially blocked electrodes is modeled using finite difference simulations, and a method is presented for the determination of currents at electrode surfaces that have an unstructured blocking pattern. The method is first applied to predict the current at purposely fabricated gold film electrodes in which monodispersed blocking disks are randomly sprinkled over the gold surface. The theoretical models are subsequently applied to the case of a basal plane pyrolytic graphite electrode modified with microdroplets of an electrochemically inactive oil. The theoretically predicted results are in good agreement with those observed experimentally.

The electro-reduction of carbon dioxide is studied by linear sweep and cyclic voltammetry in DMSO electrolyte solutions and at polycrystalline gold microdisk electrodes. An electrode reaction pathway is suggested. Numerical simulation of the reaction mechanism gives current | potential waveshapes in excellent agreement with those observed experimentally. Kinetic parameters for the reduction process are deduced from this waveshape approach, and the charge-transfer coefficient is found to be approximately 0.43 ( 0.05.

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A general approach is developed for the numerical simulation of square wave voltammetry (SWV) at uniformly accessible electrodes, based on the backward implicit method. Appropriate transformations of both the spatial coordinate normal to the electrode surface and of the time variable are developed and are shown to lead to efficient and accurate simulations. The method is applied to the modeling of electrochemically reversible processes, and the results predicting the variation of peak height, width at half-height, and the area as a function of square wave frequency and amplitude are shown to be in excellent agreement with the previously derived full analytical theory. Approximate expressions for these quantities are assessed and shown to have limited value. A superior approximation is developed for the case of the peak width at half-height.

Acoustic cavitation considerably enhances the mass transport toward a surface. When suitably fast electrochemical equipment is used, periodic peak currents can be observed. Previous observations attributed these peaks to diffusion inside a thin liquid layer present between the electrode and the bubble (Maisonhaute,

A numerical method is used to characterize the steady-state voltammetry at microdisk electrodes of a new electrocatalytic reaction. This reaction, which occurs for the oxidation of N,N-dimethylphenylenediamine (DMPD, A) in the presence of H2S (X) is believed to proceed via the following route:  A − 2e- ⇄ B, B + X → BX (k 2), B−X − 2e- ⇄ [BX]2+. Due to the presence of a reagent restricted homogeneous kinetic step, the reaction is labeled EC2XE. The numerical method for simulating this reaction scheme is based on the finite-difference formulation of coupled mass transport and kinetic equations in oblate spherical coordinates. The method is illustrated for not only the EC2XE but also the EC‘ reaction and is applicable to the simulation of steady-state limiting currents at microdisk electrodes. Iterative solutions are calculated using a Gauss−Newton scheme to overcome nonlinear homogeneous kinetic terms. The spatial convergence of the simulation for both reactions is investigated by considering the form of the concentration function describing the species. Via the comparison of working surfaces generated from simulated results, measuring the steady-state limiting current is shown to be insensitive to the resolution of EC‘, ECE, and EC2XE reactions. Experimental steady-state limiting current data is reported for the DMPD/H2S system at microelectrodes of 7.3, 19.5, and 25.0 μm diameter to verify the theory behind the EC2XE reaction. These results are shown to closely fit experimental data using a working surface interpolation method. Specifically, this method correctly predicts the variation of the steady-state limiting current with the concentration of H2S for a 19.5 μm diameter microelectrode to a relative standard deviation of 1.9%. Similar analysis for the 7.3 and 25.0 μm electrodes results in a mean value of 1.4 × 107 mol-1 cm3 s-1 for the rate constant k 2 in the DMPD/H2S system.

Investigations at microring electrodes are limited by the lack of equations that describe short and long time behavior at rings of all thicknesses. In this paper, a robust finite difference numerical method is presented for the simulation of electrochemical processes at microring electrodes of intermediate thickness. The method relies on a careful meshing strategy to minimize electrode flux errors. The accuracy of the method is first tested by comparison with a well-established reversible steady-state analytical equation. The meshes obtained through this process are reused to produce current results for chronoamperometry and linear-sweep voltammetry. In the case of chronoamperometry, simulated currents show less than ±1.5% difference compared to integral-equation methods. In the case of linear-sweep voltammetry, currents are recorded across nine decades of dimensionless scan rate. Both the dimensionless peak current and voltage at half-peak height are compared with other known methods and shown to be either comparable to or better than alternative results. In the case of the voltage at half-peak height, results are confirmed by simulations at the microdisk electrode.