Cyclic voltammograms electrolytes

Figure 12 Electrocatal3aic reduction of COj by Cuj(btc)2 in aprotic electrolyte. Cyclic voltammogram of (1) bare GC, (2) bare GC in presence of COj, (3) Cujlbtclj-coated GC, and (4) Cu3(btc)2-coated GC in presence of CO2, in a solution containing 0.01 M TBATFB/DMF, scan rate 50 mVs"L Inset cyclic voltammogram of Cuj(btc)2-coated GC in C02-saturated DMF. (Reproduced from Ref 59. Elsevier, 2012.)...

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 ... 

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.)... 

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 ).

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. 

FIG. 12 Cyclic voltammogram for Au electrode modified with el6S-tl9-T12Fc ternary complex. Electrolyte solution, aqueous 0.1 M KCl scan rate 25 mV s temperature, 5°C electrode area, 0.02 cm (geometrical). 

As mentioned above, the distribution of the various species in the two adjacent phases changes during a potential sweep which induces the transfer of an ion I across the interface when the potential approaches its standard transfer potential. This flux of charges across the interface leads to a measurable current which is recorded as a function of the applied potential. Such curves are called voltammograms and a typical example for the transfer of pilocarpine [229] is shown in Fig. 6, illustrating that cyclic voltammograms produced by reversible ion transfer reactions are similar to those obtained for electron transfer reactions at a metal-electrolyte solution interface. 

The second most widely used noble metal for preparation of electrodes is gold. Similar to Pt, the gold electrode, contacted with aqueous electrolyte, is covered in a broad range of anodic potentials with an oxide film. On the other hand, the hydrogen adsorption/desorption peaks are absent on the cyclic voltammogram of a gold electrode in aqueous electrolytes, and the electrocatalytic activity for most charge transfer reactions is considerably lower in comparison with that of platinum. 

In an ideal case the electroactive mediator is attached in a monolayer coverage to a flat surface. The immobilized redox couple shows a significantly different electrochemical behaviour in comparison with that transported to the electrode by diffusion from the electrolyte. For instance, the reversible charge transfer reaction of an immobilized mediator is characterized by a symmetrical cyclic voltammogram ( pc - Epa = 0 jpa = —jpc= /p ) depicted in Fig. 5.31. The peak current density, p, is directly proportional to the potential sweep rate, v ... 

Cyclic voltammograms of solutions of the pyrrole monomers also show a dependence on the anion present in the electrolyte and can show multiple peaks with Epa values ranging from + 1.0 to + 1.3 V in acetonitrile [57,279]) (+ 0.8 to + 1.1 V vs. 

Fig. 19. Cyclic Voltammograms of [Pt]polypyrrole (20 nm thick) in CH3CN containing various electrolyte salts. Sweep rates 50 and 100 mVs 1. Reproduced from [262].

Thick anodic iridium oxide films are formed by repetitive potential cycling between properly chosen anodic and cathodic limits [89]. The coloration (bleaching) transition is reflected in the cyclic voltammogram by a significant increase (decrease) of the electrode pseudo-capacity at a potential around 0.7 Vsce in acid electrolytes. At potentials above 0.7 V the thick film appears dark blue, while below 0.7 V the film is almost clear. 

Fig. 2.2. Cyclic voltammogram of a polished Pt electrode in 1CT2 M CH3OH/O.l M HCI04 solution, (full line) and potentiodynamic oxidation of methanol adsorbate after solution exchange with base electrolyte (dashed line). Sweep rate 60 mV/s, room temperature.

Fig. 4.3. Cyclic voltammogram for adsorbed tin on platinum, v = 10 mV/s. Experimental procedure 11 min. adsorption from a 4 x 10-4 M Sn(S04)2 solution in 0.5 M H2S04 at 0.5 V followed by electrolyte replacement with pure supporting electrolyte.

Figure 1 shows cyclic voltammograms in these two solutions. A reduction current is observed with two reduction peaks in the oxygen-saturated electrolyte. In the argon-saturated electrolyte, a single reduction peak at lower current density is observed. From the difference between the reduction currents in the two solutions, the reduction current in the... 

On the basis of obtained data of cyclic voltammograms for 3d metals oxides electrodeposition the optimal conditions (current density, potential, process time, electrolyte composition, temperature) for dense oxide films (Ni, Cr and Co) deposition on steel foil have been elaborated. Data relating to several best films are summarized in Table 1. 

Figure 2.12 (Upper) piezoelectric signal curve and (lower) cyclic voltammogram of a gold electrode in pH 3,00,5 M NajSO /H SO electrolyte. The magnitude of the voltage modulation wasSmV at 200 Hz, with a potential scan rate of33.3mV s" From Seo, Jiang and Sato (1987).

Melendres et ai (1991) reported the in-situ study of the electrode/oxide and oxide/electrolyte interfaces for a copper electrode in pH 8.4 borate buffer under potential control. The grazing-angle incidence arrangement employed by the authors is shown in Figure 2.81(a) and a cyclic voltammogram of the Cu electrode in the buffer is shown in Figure 2.81(b). 

After the chemisorption the solution in the cell was again replaced, this time by the pure electrolyte, the potential stepped back to 0.02 V vs. Pd/H2, and two cyclic voltammograms taken, as shown in Figure 3.38(b). The... 

Figure 3.74 Cyclic voltammograms of a 20nm-thick polypyrrole film on Pt in CHjCN containing different electrolytes. Two sweep rates are shown, the voltammograms showing the tower currents were taken at 50mVs , and the larger currents were obtained at lOOmVs"...

FIGURE 12.6 Cyclic voltammograms at a laccase biosensor in the absence (a) and presence (b) of 02 Sparging of 02 through the electrolyte between scans (2 min) yields reproducible and increased catalytic reduction currents (C-F) compared to ambient 02 levels. Scan rate lOmVs 1 in 0.05M acetate buffer of pH 4.5. (From [55], with permission from Wiley.)... 

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