Electrolytes voltammograms

Flavin adenine dinucleotide (FAD) has been electropolymerized using cyclic voltammetry. Cyclic voltammograms of poly (FAD) modified electrode were demonstrated dramatic anodic current increasing when the electrolyte solution contained NADH compare with the absence of pyridine nucleotide. 

The thickness 51 of a cyclic voltammogram at a fixed UWR value also conveys useful information. It is related to the scan rate u and to the capacitance Cd of the electrode-electrolyte interface via ... 

One can thus use the voltammograms of Figs. 5.27 and 5.28 to estimate Cd values of the order of200 pF/cm2 of solid electrolyte. 

When cyclic voltammograms of an electrode partially or completely covered with an adsorbate in contact with an electrolyte solution are recorded, various characteristic features of the obtained voltammogram can be used to deduce the amount of adsorbed material. This procedure can be repeated at various concentrations of the species to be adsorbed in the solution. From the obtained relationship between... 

Electrochemical studies were carried out in the above cation-deficient thiospi-nel. The cyclic voltammogram of Cu5.5SiFe4Sni2S32 in 1 M LiBF4 electrolyte between 1 and 4.6 V versus the Li/Li electrode is given in Fig 15.6. However, no clear peaks could be observed in the CV plot. 

Fig. 15.6 Cyclic voltammogram of Cu5.5SiFe4SiiT2S32 in 1 M LiBp4 electrolyte of ethylene carbonate and dimethyl carbonate.

FIGURE 27.32 Cyclic voltammogram of the Ag(lll) electrode in 1 roM NaOH + 0.5mM NaF (pH 11). Sweep rate is 0.05 V/s. The arrows indicate the positions of the voltammetric peaks and the point of zero charge (PZC) of the Ag(lll) in neutral NaF electrolyte. (From Savinova et al., 2000, with permission from Elsevier.)... 

LCEC is a special case of hydrodynamic chronoamperometry (measuring current as a function of time at a fixed electrode potential in a flowing or stirred solution). In order to fully understand the operation of electrochemical detectors, it is necessary to also appreciate hydrodynamic voltammetry. Hydrodynamic voltammetry, from which amperometry is derived, is a steady-state technique in which the electrode potential is scanned while the solution is stirred and the current is plotted as a function of the potential. Idealized hydrodynamic voltammograms (HDVs) for the case of electrolyte solution (mobile phase) alone and with an oxidizable species added are shown in Fig. 9. The HDV of a compound begins at a potential where the compound is not electroactive and therefore no faradaic current occurs, goes through a region... 

Figure 11.13 Linear cyclic voltammograms of different carbon-supported catalysts recorded in an 02-saturated electrolyte (0.5 M H2SO4) (1) Pt/C catalyst (2) Pt/C catalyst in the presence of 1.0 M methanol (3) FePc/C catalyst (4) FePc/C catalyst in the presence of 1.0 M methanol (temperature 20 °C, scan rate 5 mV s rotation speed 2500 rev min ).

Figure 11.18 Linear cyclic voltammograms of a FePc/C disk electrode and corresponding oxidation current of a Pt ring electrode maintained at 1.2 V vs. RHE, recorded at 2500 rev min in an 02-saturated 0.5 M H2SO4 electrolyte (temperature 20 °C, sweep rate 5 mV s ).

Figure 12.5 CO stripping voltammogram with a CO- tee 0.1 M H2SO4 electrolyte. Compare the data in Fig. 12.4 the CO oxidation region begins at V = 0.43 V. After CO stripping, hydrogen adsorption/desorption peaks and the beginning of the Pt oxidation range are shown.

FIG. 2 Cyclic voltammogram of the ferricenium transfer across the water-DCE interface at lOmVs. The electrochemical cell featured a similar arrangement to Fig. 1(b), but the organic phase contained 2mM of ferrocene. Heterogeneous oxidation of Fc occurred in the presence of 0.2mM CUSO4 in the aqueous phase. Supporting electrolytes were lOmM 02804 and lOmM BTPPATPBCl. The transfer of the standard tetramethylammonium (TMA+) under the same condition is also superimposed. 

The voltammograms at the microhole-supported ITIES were analyzed using the Tomes criterion [34], which predicts ii3/4 — iii/4l = 56.4/n mV (where n is the number of electrons transferred and E- i and 1/4 refer to the three-quarter and one-quarter potentials, respectively) for a reversible ET reaction. An attempt was made to use the deviations from the reversible behavior to estimate kinetic parameters using the method previously developed for UMEs [21,27]. However, the shape of measured voltammograms was imperfect, and the slope of the semilogarithmic plot observed was much lower than expected from the theory. It was concluded that voltammetry at micro-ITIES is not suitable for ET kinetic measurements because of insufficient accuracy and repeatability [16]. Those experiments may have been affected by reactions involving the supporting electrolytes, ion transfers, and interfacial precipitation. It is also possible that the data was at variance with the Butler-Volmer model because the overall reaction rate was only weakly potential-dependent [35] and/or limited by the precursor complex formation at the interface [33b]. 

Voltammogram 1 realized in Fig. 2(a) or (b) is a VCTTM recorded while adding K+ into W1 and W2 or LM of the cell containing the same concentrations of supporting electrolyte and dibenzo-18-crown-6 as those in the cell of Eq. (1). Two positive and two negative waves were observed in the VCTTM as shown as curve 1 in Fig. 2(a), when 5 x 10 " M K+ was added in both W1 and W2. 

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