Surface electroactive microparticles

Adsorbed (Surface-)Electroactive Microparticles on Solid Electrodes... 

The electrode surface was assumed to contain N electroactive metal or metal oxide centers, respectively, which can be not only uniformly but also (mimicking more realistic experimental conditions) randomly distributed an example is the results of atomic force microscopy (AFM) studies on microparticle electrodes [53]. Here, the diffusion domain approach (as described in Section 6.3.2.2.1) has been employed that is, the electrode surface is assumed to be an arrangement of independent diffusion domains of radius Fq. If all particles are of the same radius, rj, but are distributed in a random manner, then a distribution of diffusion domains with different domain radii, ro, follows. The local position-dependent coverage is given by T. The electroactive microparticle flat disks of the radius rj are located in the center of the respective diffusion domain cylinder. The simulated (linear sweep voltammetric) reaction follows a one-electron transfer, and species B is stripped from the electrode surface into the solution, forming A, or ... 

If all A, B, and R compounds are electroactive in a suitable electrolyte, voltam-mograms of the mixture must provide peaks corresponding to their respective redox processes. In solid-state voltammetry, in which separate microparticles of each one of the electroactive compounds are mechanically transferred to the surface of an inert electrode, independent electrochemical processes must occur. Accordingly, peak currents, ip j) j =A,B,R), recorded for A-, B-, and R-centered voltammetric processes, can generally be taken as proportional to the amount of each one of the compounds deposited on the electrode [131, 243-245]. If separate peaks are recorded for A, B, and R, the respective peak currents must satisfy the relationship... 

Thompson and Compton investigated, from a theoretical standpoint, the case of a spherical microparticle with an electroactive compound on its surface and attached to a solid electrode surface [33, 34]. The movement of charge was assumed to start exclusively from the contact point (or line) between the microparticle and electrode (i.e., at the three-phase boundary, if an electrolyte phase is considered) and to proceed over the particle surface only (see also Section 6.3.1). In Ref. [33], the idealized microparticle geometries of a full sphere, a hemisphere, and an inverted hemisphere have been considered (cf. Figure 6.8). 

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