Collector/generator

Log of the limiting steady-state generator/collector current of an interdigitated array of microelectrodes coated with poly(I) vs. 1/T. 

Double- and triple-band electrodes have been constructed in a similar fashion by placing thin insulating films (e.g., Mylar) between the metal foils. These have been used in generator-collector experiments, in which one electrode (the collector) is used to monitor a product formed at the other electrode (the generator). This can be considered the microelectrode equivalent of the rotated ring-... 

Another application of double, generator/collector, electrodes is what is called diffusion layer titration. This can be used for a quantitative analysis of some species in solution. The technique was first suggested by Bruckenstein and Johnson [157], and has been followed up since then, with theory [33,458] and simulations [81,458,541,554] (naming just a selection of works). 

It may be added that generator/collector cells can be implemented without convection. Double microbands [65] and interdigitated bands [294,447, 500] have been considered for this purpose, for titrations [458, 541] and for studies in electrochemically generated chemiluminescence (ECL) [539], See also the review by Amatore [46] with more references therein. 

The same procedure, both for the steady state and the time dependent system, can be extended to the channel with two bands, in generator-collector mode, as shown in Fig. f3.7. There are more boundary conditions, but they are straight-forward to apply. For details, the reader is referred to a series of articles by the Compton group [40,171,174,175,244,463] (citing just a selection of a large opus). 

Multiple microband electrodes have been used to implement, in a simple and inexpensive way, generator-collector methods of electrochemical titra-... 

Figure 5.9.2 Schematic representation of two microband electrodes operating in the generator-collector mode.

As was written in the foregoing, the major problems in electrochemical digital simulation in one dimension have now been solved. The new frontier is in two-and more-dimensional systems. During the last 20 years or so, ultramicroelectrodes have more or less replaced the mercury drop, and these form a two-dimensional diffusion space, whether they be single disks, or disk arrays, or (arrays of) strips or generator-collector strips, and so forth. Here, the problems include the fact of the large numbers of nodes required for reasonably accurate computations, and thus, long computation times and extreme computer memory needs, at the least as well as the fact that discretization usually produces (widely) banded systems of equations, so that sophisticated methods of solution need to be used in order to have sufficient memory and realistic computation times. There is also a lack of theoretical work on the numerical methods used. It is by no means certain that the familiar stability criteria will apply with these systems, which often have... 

Image generated using Generator-Collector Mode by Frinceton Applied Research SECM... 

Steam generator collector head coolability during natural circulation conditions, Allorokt/R02/A, Budapest, February 1999. 

Figure 10.2 Generator/coUector scheme oxidation of 2 mM ferrocene (Fc) in 0.1 M nBu4BF4/ CHjCN. Dashed line single band experiment (only one electrode is biased). SoUd lines generator/ collector experiment with = 0 V/SCE. Band width, w = 5 pm gap width, g = 2.5 pm and...

Arrays of electrodes operating in generator/collector mode... 

Conformal mapping techniques often allow explicit analytical equations to be formulated for steady-state currents observed at electrode arrays in a generator/collector mode (48, 52, 53, 114). The steady-state regime is experimentally the most useful regime in these operating conditions. Under steady-state conditions, the enhanced cross-talk between electrodes leads to a reduced diffusional flux of species toward the solution as time proceeds. A steady-state regime is rapidly reached in the generator/collector mode in... 

Figure 10.6 Theoretical concentration profiles calculated in the conformal space of a douhle-hand assembly (Figure 10.3C) operating in generator/collector mode in near-steady-state conditions. wig = 1 and g/2 Dt) = 0.1. C is the hulk concentration of the reactant in solution.

Figure 10.7 Double-band assembly operating in generator/collector mode. (A) Relationship between feedback (l/ampl(f) = and collection efficiency (coU(t) = in absence of a chemical reaction. (B) Effect of a chemical reaction (EC mechanism) on the collection efficiency as a function of kg D. w/g = 2 and g/2(Df) = 0.005. k is the first-order rate constant of the chemical reaction.

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