Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Normal pulse voltammograms for

Fig. 3.20 Normal Pulse Voltammograms for the reduction of 6.9 x 10 4 M tetracyanoquino-dimethane (TCNQ) in acetonitrile with 0.10 NBu4NPF6 at 293 K (platinum disc electrode with diameter 0.31 cm). Pulse duration 0.050 s. Lines are simulations with the following input parameters Ef = —0.107 V, t Ef = —0.551 V, kJ = 104 cm s-1, a = 0.5, a% = 0.35, k = 6.5 x 10-3 cm s-1, diffusion coefficients of neutral, anion, and di-anion are 1.44 x 10 5, 1.35 x 10 5, and 9.1 x 10 6 cm2 s-1, respectively. Reproduced from reference [38] with permission... Fig. 3.20 Normal Pulse Voltammograms for the reduction of 6.9 x 10 4 M tetracyanoquino-dimethane (TCNQ) in acetonitrile with 0.10 NBu4NPF6 at 293 K (platinum disc electrode with diameter 0.31 cm). Pulse duration 0.050 s. Lines are simulations with the following input parameters Ef = —0.107 V, t Ef = —0.551 V, kJ = 104 cm s-1, a = 0.5, a% = 0.35, k = 6.5 x 10-3 cm s-1, diffusion coefficients of neutral, anion, and di-anion are 1.44 x 10 5, 1.35 x 10 5, and 9.1 x 10 6 cm2 s-1, respectively. Reproduced from reference [38] with permission...
Fig. 14. Modified plots of normal pulse voltammograms for the oxidation of (A) W(CN)J" and (B) IrCl " incorporated into a protonated PVP film. Sampling time (t) (1)1, (2)2, (3)4, (4) 10 ms. Other conditions are the same as in Fig. 13... Fig. 14. Modified plots of normal pulse voltammograms for the oxidation of (A) W(CN)J" and (B) IrCl " incorporated into a protonated PVP film. Sampling time (t) (1)1, (2)2, (3)4, (4) 10 ms. Other conditions are the same as in Fig. 13...
Figure 17.6 (a) Reverse normal pulse voltammogram, (b) current measured prior to the analysis pulse in (a), and (c) normal large-amplitude pulse voltammogram at a platinum electrode for a 13.4 mM solution of Ti(IV) in the 60-40 mol% AlCl3-l-methyl-3-ethylimidazolium chloride melt at 25°C. [From Ref. 68, with permission.]... [Pg.531]

As an example of this type of study, Fig. 2 shows some back-step corrected normal pulse voltammograms obtained by Wightman s group [4] for three different substances injected into brain tissue. It can be seen that quite well-defined waves are obtained, whereas the respective cyclic voltammograms would be poorly defined. [Pg.151]

These comparisons show that our PEDOT/PSS supported catalysts are as active for methanol oxidation as the best polymer supported catalysts r >orted in the literature. However, a question that must be answered is vdiether polymer supported catalysts can provide superior performance to commercially available carbon supported catalysts. To answer this, the PEDOT/PSS supported catalyst used for the experiments in Fig. 5, was compared with a commercial 0 -TEK) carbon supported Pt-Ru alloy catalyst Fig. 6 shows normal pulse voltammograms at 60° C, while Fig. 7 shows the results of constant potential experiments (at 22 °C) over a much longer time period. In both experiments, and over all timescales studied, the carbon supported catalyst delivers currents that are as much as 10 times higher than for the polymer supported catalyst. The only conditions under which the polymer supported catalyst is superior are at short times and high potentials, which are not relevant to fuel cell operation. [Pg.178]

Figure 5. Normal Pulse voltammogram (20 s step time 10 s pulse width) for methanol (IMin IM H O/aq)) oxidation at glassy carbon rotating (1500 rpm) disc eleclrwies coated with 35%Pi-Ru (0.10 mg cmr 1.3 1 Pt.Ru) on PEDOT/PSS in a Nafion matrix. Figure 5. Normal Pulse voltammogram (20 s step time 10 s pulse width) for methanol (IMin IM H O/aq)) oxidation at glassy carbon rotating (1500 rpm) disc eleclrwies coated with 35%Pi-Ru (0.10 mg cmr 1.3 1 Pt.Ru) on PEDOT/PSS in a Nafion matrix.
The electron transport by electron self-exchange can be regarded as a kind of diffusion process, and therefore represented by the diffusion coefficient. The apparent diffusion coefficient, D pp, for the charge transport in the polymer film was obtained from the slope of the cathodic limiting current in the normal pulse voltammogram (him) vs (x the sampling time) plots by using the Cottrell equation (Eq. (10)),... [Pg.169]

For the heterogeneous electron transfer between the electrode and the redox sites confined in the film, the standard rate constant, k°, is derived from the current-potential relationship in the normal pulse voltammograms by using Eq. (11)... [Pg.169]

Potential-excitation signals and voltammograms for (a) normal pulse polarography, (b) differential pulse polarography, (c) staircase polarography, and (d) square-wave polarography. See text for an explanation of the symbols. Current is sampled at the time intervals indicated by the solid circles ( ). [Pg.517]

In normal pulse voltammetry, the current is sampled for a short period just before the drop is dislodged. The current monitored is assumed to be constant with time. In the differential pulse method, the current is monitored twice per drop the first sample is taken just before the rise in potential when the pulse starts, while the second is taken at the end of the current pulse just before it decreases back to the baseline. The difference between these two currents is Alpuise The differential pulse voltammogram is then a plot of current difference against potential. In... [Pg.179]

Despite these possible drawbacks, differential pulse voltammetry is one of today s most popular electroanalytical tools. Its principal advantages over normal pulse voltammetry are twofold (i) many analytes can be sampled with a single voltammogram since the analytical peaks for each analyte are quite well resolved, and (ii) by working with a differential current, and hence obtaining a voltammetric peak, the analytical sensitivity can be improved to about 5 x 10 to mol dm. This sensitivity is clearly superior to normal pulse voltammetry. [Pg.182]

Concerning more general application of mercury electrode in the studies on com-plexation equilibria, one should mention the paper by Jaworski et al. [59], who have investigated oxidation of mercury microelectrode in solutions with thiocyanates without any background electrolyte added. In the experiments, normal pulse voltammetry and staircase voltammetry were used. The authors have developed a general procedure for the determination of the stability constants, based on the data taken from the voltammograms. They have applied it to the analysis of Hg(II)-SCN complexes. [Pg.970]

Among the double pulse techniques, DDPV is very attractive for the characterization of multi-electron transfer processes. Besides the reduction of undesirable effects, this technique gives well-resolved peak-shaped signals which are much more advantageous for the elucidation of these processes than the sigmoidal voltammograms obtained in Normal Pulse Voltammetry and discussed in Sect. 3.3. [Pg.278]

Figure 10 Potential waveforms for normal pulse (NPV) and differential pulse voltammetry (DPV) displaying potential versus time (b), and a typical normal pulse and differential pulse voltammogram plotting current versus potential (a)... Figure 10 Potential waveforms for normal pulse (NPV) and differential pulse voltammetry (DPV) displaying potential versus time (b), and a typical normal pulse and differential pulse voltammogram plotting current versus potential (a)...
Figure Bl.28.5. Applied potential-time waveforms for (a) normal pulse voltammetry (NPV), (b) differential pulse voltammetry (DPV), and (c) square-wave voltammetry (SWV), along with typical voltammograms obtained for each method. Figure Bl.28.5. Applied potential-time waveforms for (a) normal pulse voltammetry (NPV), (b) differential pulse voltammetry (DPV), and (c) square-wave voltammetry (SWV), along with typical voltammograms obtained for each method.
Fig.2. Normal pulse, differential pulse and square wave voltammograms for 0.2 mM Cys. Fig.2. Normal pulse, differential pulse and square wave voltammograms for 0.2 mM Cys.
Np voltammograms are least affected by transformation of the oxidation products and exhibited similar distortions for the thioproline derivatives and for Cys (Fig.5). Such, however, distortions appear at different concentrations of SCOC,. For PrThz, distorted normal pulse waves are obtained with concentrations over 2.5x10 M and at pulse widths larger than 25 ms, while for Cys they appear only at concentrations exceeding lx 10 M and with the pulse width 50 ms. [Pg.396]


See other pages where Normal pulse voltammograms for is mentioned: [Pg.398]    [Pg.178]    [Pg.179]    [Pg.169]    [Pg.170]    [Pg.398]    [Pg.178]    [Pg.179]    [Pg.169]    [Pg.170]    [Pg.1060]    [Pg.1063]    [Pg.531]    [Pg.286]    [Pg.1060]    [Pg.1063]    [Pg.293]    [Pg.304]    [Pg.4207]    [Pg.4210]    [Pg.478]    [Pg.516]    [Pg.26]    [Pg.205]    [Pg.207]    [Pg.583]    [Pg.1175]    [Pg.187]    [Pg.165]    [Pg.1174]    [Pg.3]    [Pg.3]    [Pg.245]    [Pg.501]    [Pg.5539]   


SEARCH



Normal pulse voltammograms

Voltammogram

Voltammograms

© 2024 chempedia.info