Disc electrode voltammograms

The DigiSim program probably represents the current state of the art which is achievable for simulating and analysing cyclic voltammograms. This package can perform cyclic voltanunetry for a wide range of mechanisms at planar, spherical, cylindrical or rotated disc electrodes. It also computes concentration profiles. 

In a similar electrolysis (Alvarez-Gallegos and Fletcher 1998), hydrogen peroxide was electrogenerated in the presence of 1 mM Fe and during the electrolysis, aliquots of the catholyte were taken and voltammograms were recorded for each one at a rotating vitreous carbon disc electrode between the potential limits, + 1.100 V and -0.400 V (SCE). The oxidation... 

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...

The dotted line in Fig. 6.7 marks the maximum values of the ratio (A(JQq) for which a transient behavior is achieved, i.e., a well-defined peak is obtained in CV (with the relative difference between the peak and plateau currents being greater than 5 %). From the data shown in this figure, it is concluded that values of (Ag/Q ) < 0.4 are required to observe a transient behavior, whatever the electrode radius. For (Aq/Qq) > 0.5, the stationary CV response is obtained (for example, for i + 2 = 10s 1, the stationary voltammogram corresponds to scan rates below 500 mV s-1). Under these conditions, the expression of the voltammogram at disc electrodes is given by... 

Fig. 7.29 Theoretical voltammograms in staircase cyclic voltammetry (a and b) and differential staircase voltammetry (c and d) at disc electrodes for the four-electron oxidation of bis (l,2-diferrocenyldithiolene)nickel in [NBu4][PF6]/CH2C12 solution (ETj — = 120mV,...

In Sections 6.3-6.5 expressions for the analysis of the voltammograms corresponding to the simple electron transfer process O + ne-— R, obtained for uniformly accessible electrodes such as the rotating disc electrode, were presented. In this section these expressions will be applied to hydrodynamic electrodes in general. 

Fig. 9.12. Linear sweep voltammograms at a rotating-disc electrode for different sweep rates and for the same rotation speed—reversible reaction (from Ref. 15...

When concentration profiles are of interest the concentrations are often expressed as a fraction of some reference concentration - e.g., the bulk concentration of the analyte. The resulting dimensionless concentration ), cj/cief can then be shown as a function of dimensionless distance, e.g., xfrc, (for a UMDE), x(co/DY 2 (for an - rotating disc electrode), x/(Dt)1 2 (for a chronoamperogram) or x(F v /RTD)x/2 (for a cyclic voltammogram). 

Fig. 34 Voltammograms (with background correction) for the reduction of 2,6-diphenylpyrylium perchlorate at a 10 fim platinum disc electrode. The following scan rates were used (a) 250, (b) 150 and (c) 75 kV s . The substrate concentration was 10 mM. Data adapted from Amatore and Lefrou (1991).

Fig. 36 Voltammograms obtained at 25°C for the oxidation of 2 mM ferrocene in acetonitrile/0.1 M (C4H9)4NC104 at a 2-mm diameter platinum disc electrode using a scan rate of 20mVs" recorded either (a) under silent conditions, or (b) under insonation (20 kHz, 50 mW cm ) using the experimental arrangement of Fig. 35 with...

Fig. 38 The reduction of 0.5 mM 3-bromobenzophenone in DMF/0.1 M (C4H9)4NC104 solution at a 3-mm diameter glassy carbon disc electrode, (a) Cyclic voltammogram measured under silent conditions at a scan rate of 50 mV s . (b)-(d) Sonovoltam-mograms obtained with 25 W cm" intensity ultrasound at 27, 15 and 8 mm horn-to-electrode separations respectively, (e) Plot of sonovoltammetric limiting currents vs the reciprocal diffusion layer thickness. The solid lines show the theoretical expected behaviour for simple one- and two-electron processes respectively whilst the dotted line corresponds to that for an ECE mechanism with a rate constant of 600 s . ...

Fig. 43 (a) Cyclic voltammogram measured at a scan rate of 200 mV s for the reduction of 1 mM Ru(NH3)g in aqueous 0.1 M KCl. (b) Sonovoltammogram obtained in the presence of 33 W cm ultrasound with a 1 mm platinum disc electrode in a face-on geometry with a horn-to-electrode distance of 7 mm. (c) Time-resolved current signal recorded as for (b) at potentials of 0.1 and -0.5 V (vs. SCE). Data adapted from Marken el al. (1996a). 

Fig. 7.63 Disc voltammograms and luminescence intensity vs. potential of an n-GaAs (ring disc electrode (RDE)) in the presence of M Ce at pH 1 at two different rotation velocities 9 Hz (dashed) and 2,5 Hz (solid lines) scan rale 10 mV s. (After ref. [85])...

Figure 1.10 Cyclic voltammogram for deposition of CdTe at a stainless steel rotating disc electrode. Rotation rate 16 Hz, sweep rate 1 mVsSolution 10" M HTeOJ, 0.1 M CdS04 and 0.1 M KjSO. Note the...

Cyclic voltammograms recorded on polarization of a mechanically polished Pb rotating disc electrode (surface areas = 0.2 cm ) in de-oxygenated 1 M H2SO4 solution at a scan rate of 30 mV s (a) rotation speed 24 rpm (b) rotation speed 40 rpm (curve 1), 16 rpm (curve 2) and 0 rpm (curve 3). Potentials are measured vs Hg/Hg2S04 reference electrode [21]. 

Fig. 4.1 Cyclic voltammogram of a film of ferrocene-containing polyamide (4.11) evaporatively deposited on a Pt-disc electrode measured in CH3CN/O.I M [Bu4N][PF6]. Inset shows a plot of current versus scan rate. (Adapted from [38])...

Fig. 17.10 Cyclic voltammograms recorded at a 5 mm diameter Ft disc electrode in 50 mM N2H4 in dimethylethylammonium trifluoromethanesulfonate at 45 °C. The potential of the working electrode was cycled between 0.3 V (initial potential) and 1.8 V. Reprinted with permission from Walsh, D A Ejigu, A Muhammad, S Licence, P (2014) ChemElectroChem 1 281-288. Copyright 2014 Wiley VCH...

Fig. 53. Cyclic voltammograms comparing the steady-state current, with the CV currents I (peak currents according to Eq. (80)) recorded at the disc electrode of diameter d = 1 mm. Reversible reduction consuming n = 2 electrons, D = 1 x 10" m- s Constant concentration cj, variation of the sweep rates (Vs" ) (1) 0.0025, (2) 0.025, (3) 0.10 and (4) 0.25. Adapted according to [113].

Figure 1. Cyclic voltammograms of EtSCr(C0)5 PPN" (2 mM solution in THF 0.3 M n-Bu4N BF4) recorded at a gold disc electrode. Potentials refer to a Ag/AgBp4 0.02 M in THF hg.A scan rate 1 V/s (upper CV) and 0.1 V/s (lower CV) fig.B scan rate 0.1 V/s for two different turning potentials.

In cases where the mass transport conditions reach a steady state, e.g. with a microelectrode where spherical diffusion dominates (Section 11.2.4) or with a rotating disc electrode where hydrodynamic convection controls the diffusion layer thickness (Section 11.2.5), the current-voltage curve takes the form of a sigmoidal wave (Figure 11.7). The voltammogram is described by equation (11.2.49) when the kinetics are reversible. If however the... 

Figure 9.37 Effect of forced convection on voltammograms recorded using rotating disc electrode (RDE) at different reverses per minute (rpm). The positions of equilibrium potentials of Cu Cu and Sn Sn electrodes...

---