Voltammogram cyclic voltammograms

Similarly to the response at hydrodynamic electrodes, linear and cyclic potential sweeps for simple electrode reactions will yield steady-state voltammograms with forward and reverse scans retracing one another, provided the scan rate is slow enough to maintain the steady state [28, 35, 36, 37 and 38]. The limiting current will be detemiined by the slowest step in the overall process, but if the kinetics are fast, then the current will be under diffusion control and hence obey the above equation for a disc. The slope of the wave in the absence of IR drop will, once again, depend on the degree of reversibility of the electrode process. 

Figure C2.10.2. Cyclic voltammogram of Cu(l 11)/10 mM HCl and in situ measured STM micrographs revealing tire bare Cu(l 1 l)surface (-1.05 V, left) and tire (V3 x A/3)R30°-Cladsorbate superstmcture (-0.6 V, right) (from [39]).

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. 

Voltage window estimated from cyclic voltammograms contained in the reference. 

Figure 6.2-3 Cyclic voltammogram of acid [BMIM] CI /AICl3 on Au(m) Au oxidation begins...

The following two pictures (Figure 6.2-8a and b) were acquired at h-500 mV and at -I-450 mV vs. Cu/Cu and show that at h-450 mV vs. Cu/Cu monolayer high Cu clusters nucleate at the steps between different Au terraces. Thus, the pair of shoulders in the cyclic voltammogram is correlated with this surface process. 

Figure 6.2-7 Cyclic voltammogram of CuCI in acidic [BMIM] CC/AICl3 on Au(in) three UPD...

Figure 6.2-11 Cyclic voltammogram of dry [BMIM] PFg on Au(in) between the anodic and...

If Gel4 is added in an estimated concentration between 0.1 and 1 mmol dm eral processes are observed in the cyclic voltammogram (Figure 6.2-12). 

Figure 6.2-12 Cyclic voltammogram of 0.1 - 1 mmol dm Cel4 on gold in dry [BMIMj PFg",...

Figure 9 shows the first and second cycle of a cyclic voltammogram of a 0.2 molal (mol kg"1) solution of lithium bis[2,2 biphenyldiolato(2-)-0,0 ]borate in PC at a stainless steel electrode. The sweep covers the potential range from open circuit potential ER versus a lithium reference electrode up to 4500 mV versus Li and back to ER. The first cycle shows... 

FIGURE 2-2 Typical cyclic voltammogram for a reversible () + tie = R redox process. 

The cyclic voltammogram is characterized by several important parameters. Four of these observables, the two peak currents and two peak potentials, provide the basis for the diagnostics developed by Nicholson and Shain (1) for analyzing the cyclic voltammetric response. 

For multielectron-transfer (reversible) processes, the cyclic voltammogram consists of several distinct peaks if the E° values for the individual steps are successively higher and are well separated. An example of such a mechanism is the six-step reduction of the fullerenes C60 and C70 to yield the hexaanion products and C7q. Such six successive reduction peaks are observed in Figure 2-4. 

For quasi-reversible systems (with 10 1 > k" > 10 5 cm s1) the current is controlled by both the charge transfer and mass transport. The shape of the cyclic voltammogram is a function of k°/ JnaD (where a = nFv/RT). As k"/s/naD increases, the process approaches the reversible case. For small values of k°/+JnaD (i.e., at very fast i>) the system exhibits an irreversible behavior. Overall, the voltaimnograms of a quasi-reversible system are more drawn-out and exhibit a larger separation in peak potentials compared to those of a reversible system (Figure 2-5, curve B). 

FIGURE 2-6 Cyclic voltammograms for a reversible electron transfer followed by an irreversible step for various ratios of chemical rate constant to scan rate, k/a, where a = nFv/RT. (Reproduced with permission from reference 1.)... 

FIGURE 2-7 Repetitive cyclic voltammograms for 1 x 10 6 m riboflavin in a 1 niM sodium hydroxide solution. (Reproduced with permission from reference 10.)... 

For more detailed information on the theory of cyclic voltammetry, and the interpretation of cyclic voltammograms, see references (1,7,19,20). 

Example 2-2 The following cyclic voltammogram was recorded for a reversible couple Calculate the number of electrons transferred and the formal potential for the couple. 

Suimnarize the different features of the cyclic voltammogramic response for reversible and quasi-reversible systems. 

FIGURE 4-30 Cyclic voltammogram for ferrocene at a 3 pm width, 2 pm gap interdigitated microband (solid line). The dotted line represents the current of the collector electrode held at a potential of —0.1 V (Reproduced with permission from reference 95.)... 

Other techniques such as cyclic voltammogram (CV), atomic force morphology (AFM), and scanning force morphology (SFM) have also been used for... 

CV. See Cyclic voltammogram (CV) Cyanate resins, phenolic, 418 Cyclic dimers, 153... 

Figure 2. Cyclic voltammograms of a poly(2,2 -bithiophene)-coated electrode in acetonitrile containing 0.1 M Bu4NC 04.34 (Reprinted from G. Zotti, C. Schiavon, and S. Zecchin, Irreversible processes in the electrochemical reduction of polythiophenes. Chemical modifications of the polymer and charge-trapping phenomena, Synth. Met. 72 (3) 275-281, 1995, with kind permission from Elsevier Sciences S.A.)...

Figure 3. Cyclic voltammograms of 3-methylpyrrole-4-carboxylic acid in acetonitrile + 0.1 MEt4NC104.58 (Reprinted from P. G. Pickup, Poly-(3-methylpyrrole-4-carbox-ylic acid) An electronically conducting ion-exchange polymer, J. Electroanal. Chem. 225, 273-280, 1987, with kind permission from Elsevier Sciences S.A.)...

Figure 4 compares cyclic voltammograms for a redox polymer (poly-[Fe(5-amino-1,10-phenanthroline)3]3+/2+)91 and p-doping and undoping of a conducting polymer (polypyrrole).92 The voltammogram for the redox... 

Figure 4. (A) Cyclic voltammograms over a range of scan rates for a redox polymer (poly-[Fe 5-amino-1,10-phenanthrotme)3]3+/>)91 and (B) p-doping and undoping of a conducting polymer (polypyrrole) (B). [(A) Reprinted from X. Ren and P. O. Pickup, Strong dependence of the election hopping rate in poly-tris(5-amino-1,10-phenan-throline)iron(HI/II) on the nature of the counter-anion J. Electroanal. Chem. 365, 289-292,1994, with kind permission from Elsevier Sciences S.A.]...

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