Cyclic voltammetry digital simulation

A COMPARATIVE STUDY OF NUMERICAL METHODS FOR CYCLIC VOLTAMMETRY DIGITAL SIMULATION OF AN ELECTROCHEMICAL PROCESS WITH A COUPLED CHEMICAL REACTION... 

A Comparative Study of Numerical Methods for Cyclic Voltammetry Digital Simulation of an Electrochemical Process vrith a Coupled Chemical Reaction M.A.N.D.A, Lemos and A.J.L. Pombeiro... 

Lemos MANDA, Pombeiro AJL (1993) A comparative study of numerical methods for cyclic voltammetry digital simulation of an electrochemical process with a coupled chemical reaction. In Pombeiro AJL, McCleary JA (eds) Molecular electrochemistry of inorganic, bioinorganic and organometallic compounds. Kluwer Academic, Dordrecht, pp 477-482... 

For the rapid electron transfer process, which follows a reversible chemical step (CE), a procedure is presented for the determination of chemical and electrochemical kinetic parameters. It is based on convolution electrochemistry and was applied for cyclic voltammetry with digital simulation [59] and chronoamperometric curves [60]. The analysis was applied to both simulated and experimental data. As an experimental example, the electroreduction of Cd(II) on HMDE electrode in dimethylsulphoxide (DM SO) [59] and DMF [60] with 0.5 M tetraethylammonium perchlorate (TEAP) was investigated. 

The reach of cyclic voltammetry is vast. It has been applied to the investigation of simple electron-transfer reactions those with two successive electron transfers (so-called EE reactions) and with multiple electron transfers (EEE) involving electron transfer to and from compounds, say, with several benzene rings. The technique has been applied to complex sequences in which an electron transfer is followed by a chemical reaction step, and then by another electron transfer (ECE reactions), etc. The complexity of some of the reaction sequences investigated by cyclic voltammetry lends itself well to calculations that need computers the classic work of Feldburg in this direction (digital simulation) has been already mentioned (Section 7.5.19.2). 

Digital simulation software, which is now commercially available, is useful in analyzing cyclic voltammograms of complicated electrode reactions [67]. If we assume a possible reaction mechanism and can get simulated CV curves that fit the experimental CV curves, we can confirm the reaction mechanism and obtain thermodynamic and kinetic parameters concerning the electron transfer and chemical processes. By the development of simulation softwares, cyclic voltammetry has become a very powerful technique. On the contrary, without a simulation software, cyclic voltammetry is not as convenient.14)... 

The task now at hand is to find solutions to these second-order differential equations under theboundary conditions defined by the electroanalytical method in question. Nowadays, this is most often accomplished by numerical integration, known in electroanalytical chemistry as digital simulation. It is beyond the scope of this chapter to go into the mathematical details, and the interested reader is referred to the specialist literature [33]. Commercial user-friendly software for linear sweep and cyclic voltammetry is available (DigiSim ) software for other methods has been developed and is available through the Internet. 

Digermanes, unsymmetrically substituted, 3, 787 Digermenes, preparation, 3, 796 Digestion studies, stability, 12, 612-613 DIGISIM, in cyclic voltammetry, 1, 282-283 Digital simulations, in cyclic voltammetry, 1, 282 Dihalides, in chromium mononitrosyl complexes, 5, 302 Dihaloarenes, cross-coupling polymerization, 11, 659... 

One of the main uses of digital simulation - for some workers, the only application - is for linear sweep (LSV) or cyclic voltammetry (CV). This is more demanding than simulation of step methods, for which the simulation usually spans one observation time unit, whereas in LSV or CV, the characteristic time r used to normalise time with is the time taken to sweep through one dimensionless potential unit (see Sect. 2.4.3) and typically, a sweep traverses around 24 of these units and a cyclic voltammogram twice that many. Thus, the explicit method is not very suitable, requiring rather many steps per unit, but will serve as a simple introduction. Also, the groundwork for the handling of boundary conditions for multispecies simulations is laid here. 

Digital simulation — Data from electrochemical experiments such as cyclic voltammetry are rich in information on solution composition, diffusion processes, kinetics, and thermodynamics. Mathematical equations describing the corresponding parameter space can be written down but can be only very rarely solved analytically. Instead computer algorithms have been devised to ac-... 

Fig. 16 Working curve for the EC dimerization mechanism during cyclic voltammetry. Calculated by digital simulation. (Ahiberg et al., 1980b)...

In Fig. 6 is shown a series of cyclic voltammograms which demonstrate that the catalytic properties of the the complex are due to chemistry that originates from the second bpy-based reduction wave. Using bulk electrolysis and cyclic voltammetry techniques combined with digital simulation methods, the following mechanism can be proposed for electrocatalytic CO production in CH CN... 

Digital simulation techniques allow the conclusion that the cyclic voltammetry data is consistent with mechanism that is first order in CO and first order in... 

In cyclic voltammetry, the anodic portion on the reverse scan is not affected as much as the forward response by the coupled reaction (Figure 12.3.2). The ratio of (with /pa measured from the extension of the cathodic curve as described in Section 6.5) increases with increasing scan rate as shown in the working curve in Figure 12.3.6 (25). The actual i-E curves can be drawn using series solutions or a table given by Nicholson and Shain (25) or by digital simulation. 

Peerce, P. J., Bard, A. J. (1980). Polymer films on electrodes m. Digital simulation model for cyclic voltammetry of electroactive polymer film and electrochemistry of poly(vinylferrocene) on platinum. J Electroanal Chem 114, 89-115. 

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