Potentiostatic regime

Mishina F, Karantonis A, Yu Q-K, Nakabayashi S. 2002. Optical second harmoitic generation during the electrocatalytic oxidation of formaldehyde on Pt(lll) Potentiostatic regime versus galvanostatic potential oscillations. J Phys Chem B 106 10199-10204. 

In a number of works, a potentiostatic regime has been used for the experimental and theoretical study of the anodization of aluminum and other valve metals.80 Upon the application of a constant potential step, Va, barrier-forming electrolytes are characterized by a sharp increase in the anodic current to a certain maximum. Both the slope and the maximum are determined by the impedance of the cell circuit. Subsequently, there is a continuous decrease in the anodic current, which is due to oxide growth. The decay of the anodic current can be described by the expression81... 

In the majority of cases, potentiostatic regimes were used. In [189,197], a method was developed to obtain layer-by-layer metallic precursors. This allows one to avoid the semiempirical procedure of solution composition optimization. Moreover, it makes possible deposition under kinetic or mixed control, which improves the deposit morphology. Two- or three-step potentiostatic [177] and pulsed [175] modes which ensure the optimal deposit compositions have also been developed. 

C. Gabrielli, F. Huet, and M. Keddam, "Investigation of Electrochemical Processes by an Electrochemical Noise-Analysis Theoretical and Experimental Aspects in Potentiostatic Regime," Electrochimica Acta, 31 (1986) 1025-1039. 

FIGURE 5.45. The current density versus voltage curve of a p-type Si electrode in NH4F (0.3 M, pH 3.5) recorded with 50mV/s. Current oscillations are observed in the potentiostatic regime for potentials positive of the one corresponding to the second current minimum. After Lehmann.(Reproduced by permission of The Electrochemical Society, Inc.)... 

Considering the influence of applied conditions on stoichiometry deviation in SiC under electrochemical treatment, let us also present some data related to silicon carbide anodization in the potentiostatic regime. The treatment was performed using HF-based electrolyte under conditions where anodic current density values are 4-10 mA cm-2. In spite of the value of the current being comparable with that used for the formation of nanoporous PSC structures, SiC anodization under potentiostatic conditions results in built-in adherent film ( anodic film in the... 

Figure 7.7 SEM images showing the honeycomb structure of the anodic film obtained as a result of SiC anodization in potentiostatic regime (a), (b) shows inhomogeneity of the structure of anodic film, related to a structural defect in the SiC specimen...

Figure 5.4 Current-time curves for the 4 h and 20 min (inset) of anodization under a potentiostatic regime at 20 V in 1 M H3PO4 + 1 M NaOH + 0.5 wt% HF solution. The four distinct phases of anodization are marked with roman numerais in the inset.

The predicted oscillatory behaviour has been found for the potentiostatic regime of the process. Figure 4.3 shows such example when the weight of the cathode, rising in total, exhibits clearly distinct local oscillations. 

Fig. 2.23 Silver deposits electrodeposited from 0.50 M AgNOs in 100 g dm NaN03 (a) in the potentiostatic regime of electrolysis onto Ag wire electrode without the addition of H3PO4. Quantity of electricity 100 mA h cm. Deposition overpotential 120 mV. The exchange current density 26 mA cm and (b) in the galvanostatic regime of electrolysis onto Pt wire electrodes with the addition of 6 g dm H3PO4. Current 30 mA. Time 2 s. The exchange current density 5 mA cm (Reprinted from Refs. [13, 65, 66] with kind permission from Springer)...

The typical Pb granules obtained in the potentiostatic regime of electrolysis are shown in Fig. 2.34. Similar to silver granules, granules of various shapes were produced by the electrodeposition processes. The granules, such as octahedrons and hexagons, as weU as many various types of twinned particles single-twinned, multiply-twinned (MTPs), lamellar-twinned (LTPs), and many other complicated... 

Fig. 4.8 Copper deposits obtained from 0.10 M CUSO4 in 0.50 M H2SO4 on a Cu wire electrode with a quantity of electricity of 20 mA h cm in (a) the constant potentiostatic regime an overpotential 210 mV initial current density 6.5 mA cm , as well as by the different pulsating overpotential (PO) regimes (b) initial average current density 6.5 mA cm = 322 mV pulse-...

Figure 5.9 shows the honeycomb electrodes obtained at a constant overpotential of 1000 mV (Fig. 5.9a) and by the PO regime with the overpotential amplitude of 1000 mV, deposition pulse, t, of 10 ms, and pause duration, fp, of 50 ms (Fig. 5.9b). Holes obtained by these regimes of electrolysis of detached hydrogen bubbles are shown in Fig. 5.9c (the constant potentiostatic regime) and 5.9d (the PO regime). The bottom of the hole obtained at the constant overpotential was relatively smooth (Fig. 5.9c), while the one obtained by the PO regime was cmistructed from the small...

Fig. 5.9 The honeycomb-like electrodes, holes, and cross sections of the honeycomb-like electrodes obtained by (a, c, e) the constant potentiostatic regime at an 1000 mV and (b, d, f) the regime of pulsating overpotential (PO). Overpotential amplitude 1000 mV. Deposition pulse 10 ms. Pause duration 50 ms. Solution 0.15 M CUSO4 in 0.50 M H2SO4 (Reprinted from Ref. [29] with permission from the Serbian Chemical Society, Ref. [21] with permission from Elsevier and Refs. [5, 23, 51] with kind permission from Springer)...

Comparative survey of powders obtained in potentiostatic and galvanostatic regimes of electrolysis is shown in Fig. 6.4. In spite of the fact that particles obtained by galvanostatic deposition are less dendritic than those obtained by potentiostatic deposition due to smaller overpotential at the end of the galvanostatic than the potentiostatic regimes [5], there is no any substantia] difference in the morphology of powder particles obtained between these two constant regimes of... 

Fig. 6.7e), Pb particles of irregular shape (denoted as irregular crystals or precursors of dendrites) (Fig. 6.7f) were obtained by the appropriate square-wave PO with the overpotential amplitude equal to the overpotential of electrodeposition in the constant potentiostatic regime of electrolysis [5, 38]. As a remainder, in the constant potentiostatic regimes of electrolysis, irregular crystals are formed at lower overpotentials than the fem-like dendrites. 

Fig. 6.11 (a) Particle size distribution curves for Cu powders obtained by potentiostatic electrodeposition on Pt electrodes, (b) particle size distribution curves for Cu powders obtained by galvanostatic electrodeposition on Pt electrodes. The surface area of the electrode 0.63 cm and (c) particle size distribution curves for Cu powders obtained by the potentiostatic and galvanostatic (the average current in the potentiostatic regime) electrodepositions on Cu electrodes. The surface area of the electrode 0.63 cm (Reprinted from Refs. [6, 7, 62] with kind permission from Springer)... 

Figure 11.1 Experimental arrangement used for analyzing the current noise in potentiostatic regime. Nj and N2 are the parasitic noises of the measurement channels. The figure shows the Fourier analyzer, amplifiers and filters. Reprinted from Ref [89] with kind permission from Springer Science+Business Media.

Gabiielli, C., Huet, F. and Keddam, M. (1986) Investigation of electrochemical processes by an electrochemical noise analysis. Theoretical and experimental aspects in potentiostatic regime. Electrochimica Acta, 31,1025-1039. 

The analysis above is performed for a stack operated in the potentiostatic regime (constant r °). In this regime, propagation of the thermal wave causes growth of the stack current the respective variation of the mean current density J can be obtained from... 

Morphologies of Powdered Deposits and Powder Particles Obtained by the Constant Potentiostatic Regime... 

Fig. 3.24 Particle size distribution curves for copper powders obtained by the potentiostatic and galvanostatic (the average current in the potentiostatic regime) electrodepositions on copper electrodes. Surface area of the electrode 0.63 cm (Reprinted from [83] with permission from Springer.)...

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