A.c. cyclic voltammetry

A particularly important, powerful, and novel capability of the instrument described here is the rather short 0.1 s minimim measurement interval required to define a complete admittance spectrum (Item E, above). Unfortunately, a major sacrifice has been made to realize such rapid measurement characteristics. Specifically, the ability to monitor in real time some aspect of the cell or faradaic admittance has been waived. With measurement intervals less than 5-6 seconds, the possibility of interspersing the essential data processing for some useful type of real-time cell or faradaic admittance readout does not exist with the instrumentation described. Because we normally either prefer or are forced (e.g., a.c. cyclic voltammetry) to use the advantages of short measurement intervals, our... 

A technique which is becoming increasingly important in our laboratory is a.c. cyclic voltammetry. This experiment is run on a stationary electrode [Hanging Hg drop (HMDE), Pt, Au, graphite, etc.]. The d.c. potential staircase is swept first in one direction and then the other. The slopes for the forward and reverse scans usually are equal in magnitude, but opposite in sign. The ramp amplitude encompasses one or more admittance peaks. The FT-FAM measurement is performed in this context. 

FIGURE 2.41. a Reductive cyclic voltammetry of bianthrone in DMF + 0.1 Mn-Bu4NC104 at 21°C. Scan rate, 10 V/s. b Two conformations of bianthrone. c Reduction and oxidation pathways. Adapted from Figure 11 in reference 44, with permission from Routledge/Taylor and Frances Group, LLC. 

Fig. 12.11 A schematic view for constructingmultilayerfilms on substrate, (b) Photographs of multilayer films of ITO/(PDDA/PSS-GS/PDDA/Mn02)n, n = 0, 5,10, and 15 for A, B, C, and D, respectively, (c) Cyclic voltammetry curves of ITO/(PDDA/PSS-GS/PDDA/MnO2)10 electrode at different scan rates, (d) Charge-discharge behavior of an ITO/(PDDA/PSS-GS/PDDA/MnO2)10 electrode at different current densities.

Fig. 2 Reduction of Ceo and C70 in MeCN/PhMe at -10°C using (a and c) cyclic voltammetry at a 100 mV scan rate and (b and d) differential-pulse voltammetry at a 25 mV s scan rate. Reprinted with permission from Ref. 31. Copyright 1992 American Chemical Society.

Figure 3a-c. Cyclic voltammetry of copper-2% zinc alloy at 0.012 V/min in phosphated saline supporting electrolyte as listed in Figure la (a), with addition of 46.2 g/L of BSA (b), and human y-globulin (c). 

Figure 6 Potential waveforms for linear sweep (LSV (a) and cyclic voltammetry (C V) (b) displaying potential versus time including the initial and final potentials, and a typical linear sweep voltammogram and cyclic voltammogram plotting current versus potential...

Figure 11.3 Typical features and behavior of traditional or new carbon pastes and the respective electrodes in current flow measurements, (a-d) Cyclic voltammetry of [Fe(CN)g]3/ - in 0.1 M KCI, c(Fe) = 5mM, lighter line, GCE (a,b) or GC-IL (c,d), hitherto unpublished records (e) Adsorptive stripping voltammetry of Ni" at the low parts per billion level in 0.1 M ammonia buffer containing 10 iM DMG (dimethyl glyoxime)H-Hg". Legend curve (1) blank, (2) c(Ni") = 5ppb, and (3) c(Ni") = 10 ppb. Note symbol Oj denotes the reductive response of oxygen...

Figure llA Waveforms used in linear sweep (a) and cyclic voltammetry (b and c). j, 2 and 3 are the starting and reversal potentials while v is the scan rate. 

Amatore C, Pebay C, Thouin L, Wang A (2009) Cyclic voltammetry at microelectrodes. Influence of natural convection on diffusion layers as characterized by in situ mapping of concentration profiles. Electrochem Common 11 1269-1272... 

FICU RE 3.68 Electrografting of 5-nitroindole anion (NI ) on a GC electrode. (A) Repetitive cyclic voltammetry of Nl" in CAN. (B) (a) GC-NI electrode (b) voltammogram of 1-methyl-5-nitroindole under the same conditions. (Adapted from Munoz, L. S., C. Frontana, and F. J. 

A mixture of LiOH and EMD is heated at 420 °C for 2-3 h in order to allow molten LiOH to penetrate into the pores of the EMD. The mixture is then heated from 650 to 800 °C to produce LiMn204. The amount of LiOH and EMD in the mixture must be stoichiometric (LiOH Mn02 = 1 2). The product, LiMn204, is usually tested by cyclic voltammetry (Fig. 22) a good LiMn204does not have peaks at a and b.(peak a (3.3 V) would be due to the oxygen deficiency and peak b (4.5 V) to replacement of the Li ion sites by Mn4+... 

The cleavage mechanism can be clarified by cyclic voltammetries as shown in Figure 5. In aprotic solution (curves a) steps (l) and (2) correspond to the successive electron transfers leading finally to the dianion. On the other hand, in protic solution (curve c), step (2) has disappeared while step (l) has grown and then obviously corresponds to an ECE process. Anyhow, and whatever the medium, step (3) is identified as that in which the produced olefin (here 1,1-diphenylethylene) is reduced in all cases. 

C.G. Vayenas, A. loannides, and S. Bebelis, Solid Electrolyte Cyclic Voltammetry for in situ Investigation of Catalyst Surfaces, J. Catal. 129, 67-87 (1991). 

J. Yi, A. Kaloyannis, and C.G. Vayenas, High Temperature cyclic voltammetry of Pt electrodes in solid electrolyte cells, Electrochim. Acta 38(17), 2533-2539 (1993). 

Among the peculiar features of 2-bromoamides there are the following i) possibility of substitution at the tertiary C-Br (RCO2H, RR NH, or a saccharide, as the nucleophiles) ii) chiral stability and stereochemical control at the secondary C-Br atom (RR NH, ROH or a saccharide as the nucleophiles) iii) the presence of bromine allows cyclic voltammetry and electroreduction at controlled potential both of starting compounds and relevant intermediates iv) the Ca polarity can be reversed upon electroreduction, and the resulting Ca enolate forms a C-C bond (CO2 as the electrophile). 

It was reported recently [216] that optical-quality PbTe thin films can be directly electrodeposited onto n-type Si(lOO) substrates, without an intermediate buffer layer, from an acidic (pH 1) lead acetate, tellurite, stirred solution at 20 °C. SEM, EDX, and XRD analyses showed that in optimal deposition conditions the films were uniform, compact, and stoichiometric, made of fine, 50-100 nm in size, crystallites of a polycrystalline cubic structure, with a composition of 51.2 at.% Pb and 48.8 at.% Te. According to optical measurements, the band gap of the films was 0.31 eV and of a direct transition. Cyclic voltammetry indicated that the electrodeposition occurred via an induced co-deposition mechanism. 

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