Current -potential curves for

The validity of Eq. (3-15) further follows from the results given in Fig. 3-4. It represents the current-potential curve for a buried storage tank. The difference f/ n - I/off is proportional to the current /. The quotient R is equal to the grounding resistance of the tank. The (/) curve corresponds to the true polarization curve. 

FIGURE 1-7 Current-potential curve for the system O + ne - " R, assuming that electron-transfer is rate limiting, C0 = CR, and a = 0.5. Hie dotted lines show the cathodic ((.) and anodic ( ) components. 

Figure 4-12 Current-potential curve for a platinum electrode in 0.5 M H2S04. Regions of oxide formation (QJ and reduction (Qc) as well as formation, of hydrogen (Hc) and its oxidation (H,) are indicated. (Reproduced with permission from reference 33.)...

Crystal surface specificity of the potential of zero charge, 152 Current-potential curves for bipolar membranes, 228 of iron dissolution in phosphoric acid,... 

Fig. 2.4i. Current-potential curves for three electroactive solutes A,...

Figure 12. Current-potential curves for Ni(II)-cyclam (1 mM) in an aqueous 0.1 M KC104 solution (pH 4.5) under N2 (a) or C02 (b) at a hanging mercury drop electrode.135 Scan rate 0.1 V/s.

Fig. 32. Cyclic current-potential curve for Au(l 11), covered with an octadecanethiol SAM, in 0.1 M H2SO4 + 1 mM CUSO4. Scan rate 10 mV s-1. The C18-SAM blocks Cu deposition up to very high overpotentials. Inset Current response of a bare Au(lll) electrode for the same potential cycle [98],...

Fig. 1. Current-potential curves for a generalized electroless deposition reaction. The dashed line indicates the curve for the complete electroless solution. The partial anodic and cathodic currents are represented by ia and ic, respectively. Adapted from ref. 28. 

Fig. 3. Current-potential curves for anodic oxidation of H2CO on different metals. Dotted lines current attributable to the anodic dissolution of Cu and Co electrodes. Solution composition 0.1 mol dm-3, 0.175 mol dm 3 EDTA, pH = 12.5, T — 298 °K. Adapted from ref. 38.

Figure 4.2 Current-potential curve for a Langmuir isotherm whose potential dependence is given by Eq. (4.7). Such curves are obtained by a slow potential sweep. The absolute value of the current depends on the sweep rate (see text).

Figure 8.6 Current-potential curves for 0.05 M Fe2+/Fe3+ in 0.5 M H2SO4 at SnC>2 electrodes with two different donor concentrations (a) 5 x 1019 cm 3, (b) 5 x 1017 cm-3 (data taken from Ref. 5).

Figure 9.3 Current-potential curves for chloride evolution on platinum from aqueous solutions data taken from Ref. 4.

Figure 14.7 Current-potential curves for two different Reynolds numbers.

Figures 3 and 4, respectively, show thin-layer current-potential curves for polycrystalline Au and Ir in molar sulfuric acid before and after exposure to a 2 mM HQ solution. For smooth Au, no changes in the voltammetric curves are seen. In comparison, a prominent anodic oxidation peak is observed for Ir after pretreatment with HQ. These observations, which indicate that Ir is reactive towards HQ but Au is not, are consistent with what is known from the literature on homogeneous organometallic chemistry (21) Ir and Pt complexes are reactive towards a variety of organic compounds, whereas Au is inert.

Figure 7 shows current-potential curves for Pt and Au precoated with DHT at half coverage. At Pt, no quinone/diphenol redox reaction is observed. Clearly,... 

Figure 41. Calculated current-potential curves for various interaction parameters of r for r > 0 and n = 1.

Wagner-Traud Diagram, According to the mixed-potential theory, the overall reaction of the electroless deposition, [Eq. (8.2)] can be described electrochemically in terms of three current-potential i-E) curves, as shown schematically in Eigure 8.2. First, there are two current-potential curves for the partial reactions (solid curves) (1) ic =f(E), the current-potential curve for the reduction of ions, recorded from the rest potential E eq M the absence of the reducing agent Red (when the activity of is equal to 1, eq,M E m) and (2) = f(E), the current-potential... 

Figure 8.2. Wagner-Traud diagram for the total (/total) rid component current potential curves (/, / ) for the overall reaction of electroless deposition.

Figure 8.3. Evans diagram of current-potential curves for a system with two different simultaneous electrochemical reactions. Kinetic scheme Eqs. (8.4) and (8.5).

Electroless Deposition of Copper. The basic ideas of the mixed-potential theory were tested by Paunovic (10) for the case of electroless copper deposition from a cupric sulfate solution containing ethylenediaminetetraacetic acid (EDTA) as a complexing agent and formaldehyde (HCHO) as the reducing agent (Red). The test involved a comparison between direct experimental values for and the rate of deposition with those derived theoretically from the current-potential curves for partial reactions on the basis of the mixed-potential theory. 

Figure 8.4. Current-potential curves for the reduction of Cu ions and the oxidation of reducing agent Red, formaldehyde, combined into one graph (an Evans diagram). Solution for the Tafel line for the reduction of Cu ions O.IM CUSO4, 0.175M EDTA, pH 12.50, Egq (Cu/Cu ) = -0.47 V versus SCE for the oxidation of formaldehyde 0.05 M HCHO and 0.075 M EDTA, pH 12.50, (HCHO) = -1.0 V versus SCE temperature 25 0.5°C. (From Ref. 10, with permission from the American Electroplaters and Surface Finishers Society.)...

Figure 8.6. Current-potential curves for a gold electrode at 75°C. Base electrolytes, KOH and KCN. Curve 1, 2 X 10 M KAu(CN)2 without KBH4 curve 2,0.1 M KBH4 without KAu(CN)2 curve 3, 2 X 10 MKAu(CN)2 and 0.1 M KBH4. Potential scanned at 5.56 mV/s. (From Ref 21, with permission from the Electrochemical Society.)...

Electroless Deposition in the Presence of Interfering Reactions. According to the mixed-potential theory, the total current density, is a result of simple addition of current densities of the two partial reactions, 4 and However, in the presence of interfering (or side) reactions, 4 and/or may be composed of two or more components themselves, and verification of the mixed-potential theory in this case would involve superposition of current-potential curves for the electroless process investigated with those of the interfering reactions in order to correctly interpret the total i-E curve. Two important examples are discussed here. 

Figure 8.10. Effect of NaCN on the current-potential curves for reduction of Cu in an electroless solution at 25°C containing 0.05 M CUSO4, 0.075 M EDTP [1,1,1, -(ethylenedinitrilo)tetra-2-propanoll, and 5.8mL/L of HCHO. The Pt cathode (0.442 cm ) was rotated at 100rpm the scan rate is lOmV/s. (From Ref. 45, with permission from the American Electroplaters and Surface Finishers Society.)...

Extension of this treatment to pulse techniques can, in principle, be made for several cases. In the case of square-wave voltammetry, theoretical current-potential curves for reversible electron transfer between species in solution are given by [184, 185]... 

Assume that the reaction ox + c <=> red at the planar electrode is diffusion controlled. Sketch and correlate the concentration profiles Cox =f(x), where x is the distance from the electrode surface to the bulk of the solution, with the shape of the current-potential curve for electrolysis carried out at (a) a stationary disk electrode and (b) a rotating disk electrode. Support your explanation by the equations. (Skompska)... 

In many electrochemical techniques, we measure current-potential curves for electrode reactions and obtain useful information by analyzing them. In other techniques, although we do not actually measure current-potential curves, the current-potential relations at the electrodes are the basis of the techniques. Thus, in this section, we briefly discuss current-potential relations at the electrode. 

Fig. 5.6 Current-potential curves for the processes controlled by the mass transport of electroactive species. Curves 1 to 3 are for reversible processes in solutions containing (1) both Ox and Red, (2) Ox only, and (3) Red only. Curves 4 and 4 are for an irreversible reduction (curve 4) and oxidation (curve 4 ) in...

AgCl electrode) and the cathodic current due to the reduction of hydrogen ion begins to flow at about -1.1 V. Between the two potential limits, only a small current (residual current) flows. In curve 2, there is an S-shaped step due to the reduction of Cd2+, i.e. Cd2++2e +Hg <=t Cd(Hg). In DC polarography, the current-potential curve for the electrode reaction is usually S-shaped and is called a polaro-graphic wave. 

Fig. 5.14 The DC and AC polarographic circuits (a) and the current-potential curves for DC and AC polarographies (b).

Fig. 2.13 Influence of k0 on the shape of the current-potential curve, for constant a, Jfc, > k2 >...

Wagner and Traud [141] developed the theory of mixed potentials in order to explain the corrosion of electrode surfaces. This theory assumes that the measurable current—potential curves for an electrode where more than one electrochemical reaction takes place simultaneously is represented by... 

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