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Cyclic voltammetric characteristics

Simulation of the Cyclic Voltammetric Characteristics of a Second Order EC Catalytic Mechanism... [Pg.71]

V. Levi and D. Anrbach [1997] Simnltaneons Measnrements and Modehng of the Electrochemical Impedance and the Cyclic Voltammetric Characteristics of Graphite Electrodes Doped with Lithium J. Phys. Chem. B 101, 4630-4640. [Pg.561]

FIGURE 1.11. Convolution of the cyclic voltammetric current with the function I j Jnt, characteristic of transient linear and semi-infinite diffusion. Application to the correction of ohmic drop, a —, Nernstian voltammogram distorted by ohmic drop , ideal Nernstian voltammogram. b Convoluted current vs. the applied potential, E. c Correction of the potential scale, d Logarithmic analysis. [Pg.23]

As transpires from equation (2.2), a steady state is established by mutual compensation of diffusion and chemical reaction. The concentration profile is indeed the product of a time-dependent function, i, by a space-dependent function in the exponential. The conditions required for the system to be in zone KP, K small and A large, will often be termed pure kinetic conditions in following analyses. Besides its irreversibility, the main characteristics of the cyclic voltammetric wave in this zone can be derived from its dimensionless representation in Figure 2.2b and its equation (see Section 6.2.1),4 where... [Pg.82]

TABLE 2.1. Characteristics of the Irreversible Cyclic Voltammetric Responses (Pure Kinetic Conditions) for the Main Mechanisms That Involve the Coupling of a Fast Electron Transfer and a Homogeneous Rate-Determining Follow-up Reaction... [Pg.105]

In cyclic voltammetry, the current-potential curves are completely irreversible whatever the scan rate, since the electron transfer/bond-breaking reaction is itself totally irreversible. In most cases, dissociative electron transfers are followed by immediate reduction of R, as discussed in Section 2.6, giving rise to a two-electron stoichiometry. The rate-determining step remains the first dissociative electron transfer, which allows one to derive its kinetic characteristics from the cyclic voltammetric response, ignoring the second transfer step aside from the doubling of the current. [Pg.189]

The comparison of the voltammetric characteristics of PWig and P2W18 is useful to highlight the peculiarities of the former complex. Figure 21 shows in superimposition the cyclic voltammograms (CVs) of the two complexes in a pH 0.3 sulfate medium. The potential domain was selected to avoid any deleterious derivatization of the electrode surface [28]. Furthermore, such domain is the most useful for elucidation of electrocatalytic processes. Here, the voltammetric pattern is restricted to the first three waves observed for PWig in this medium. In... [Pg.660]

Figure 32 shows a typical microelectrode voltammogram for an electro-chemically reversible system under near steady-state conditions. Of course at very fast scan rates the behaviour returns to that of planar diffusion and a characteristic transient-type cyclic voltammetric response is obtained as the mass transport changes from convergent to linear diffusion. [Pg.66]

The oligophenylenevinylenes 3 fe-g as models for PPV belong to the class of redox-systems with extended rr-conjugation. Their cyclic voltammetric description reveals three most characteristic properties with increasing chain length [99, 102, 103] ... [Pg.40]

For reduction, relevant data from polarographic and cyclic voltammetric experiments are summarized in Tables 1 and 2, respectively. For the results in Table 1 the variety of solvents and reference electrodes used makes comparisons difficult. It is clear, however, that even with the activation of a phenyl substituent (entries 6,7,9-14) reduction occurs at very cathodic potentials. In this context it is worth noting that in aprotic solvents at ca. — 3 V vs. S.C.E.) it becomes difficult to distinguish between direct electron transfer to the alkyne and the production of the cathode of solvated electrons. Under the latter conditions the indirect electroreductions show many of the characteristics of dissolving metal reductions (see Section II.B). Even at extreme cathodic potentials it is not clear that an electron is added to the triple bond the e.s.r. spectra of the radical anions of dimesitylacetylene and (2,4,6,2, 4, 6 -hexa-r-butyldiphenyl)acetylene have been interpreted in terms of equal distribution of the odd electron in the aromatic rings . [Pg.224]

During the electrolysis it is advisable to obtain some indication of what is going on in the cell. An indicator microelectrode in the electrolytic cell is valuable in order to follow the progress of the electrolysis and to detect intermediates. An intermediate more easily reducible than the substrate, for example, may be detected as a small prewave, and its halfwave potential or other voltammetric characteristics used for its identification. Polarographic or cyclic voltammetric curves measured during the electrolysis also present a means of monitoring the process. The combination of electrochemical and optical tech-... [Pg.280]

Cyclic voltammetric measurements on the resulting electrodes clearly show the presence of the complexes, and, from Ej, values for the RuIII/II couples, that they survive the attachment procedure with their characteristic redox properties intact. XPS (X-Ray... [Pg.136]

Plots of the peak current densities observed during the scan toward negative potentials, t p versus v l/2, extracted from the cyclic voltammetric data (see insert, Figure 3.7) were found to be linear with a zero intercept. This behavior is characteristic of a strictly diffusion controlled process for which... [Pg.205]

Cyclic voltammetric studies of these metallodendrimers showed one reversible oxidation wave characteristic of independent, non-interacting redox centers. Also, the use of these materials for modification of electrode surfaces was... [Pg.392]


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