Conditions galvanostatic

Catalytic rate measurements under potentiostatic or galvanostatic conditions were carried out using a galvanostat-potentiostat (Amel type 553). The reactant gas mixture was delivered at total flowrates of 1-2 x 10- mol sec, with partial pressures Pno. Pco. Ppropene varied between 0 - 6.5 k Pa, 0 - 1.5 k Pa, 0 - 0.4 k Pa, respectively with Phc, bringing the total pressure to 1 atmosphere in every case. Conversion of the reactants was typically =15%. Control experiments confirmed that the Au reference and counter electrodes were catalytically inert under all conditions. 

In cases where the values of 5,.(, and thns of f., are large enough (without significant convection in the electrolyte solntion), another limiting state is attained which is typical for galvanostatic conditions and where the reactant concentration at the surface falls to zero (Fig. 3b). For the time required to attain this state, Eq. (11.6) yields... 

Passivation looks different when observed under galvanostatic conditions (Fig. 16.2b). The passive state will be attained after a certain time t when an anodic current which is higher than is applied to an active electrode. As the current is fixed by external conditions, the electrode potential at this point undergoes a discontinuous change from E to Ey, where transpassive dissolution of the metal or oxygen evolution starts. The passivation time t will be shorter the higher the value of i. Often, these parameters are interrelated as... 

The ohmic potential drop can be compensated by means of positive feedback of the potentiostat or by algebraic subtraction under potentiostatic or galvanostatic conditions, respectively. 

In order to prove the S-shaped character of the polarization curve, the system was studied galvanostatically. The model predicts that the sandwiched branch of the polarization curve should be stable, and therefore measurable under galvanostatic conditions. Figure 6.10 shows the results of the experiment depending on the scan rate, an S-shaped curve can be observed in the back scan, i.e., from high to low current. At low... 

The compact, nonporous anodic alumina film is the most suitable for fundamental investigations. It is grown by anodization, mostly under constant-current (galvanostatic) conditions, in neutral solutions of borates, tartrates, citrates, and phosphates, all of which possess significant buffering capacity and hence do not allow significant dissolution of the oxide. 

Particle size of the micelle was determined by light scattering. Distance between the copper electrodes was maintained at 1 cm. After electrochemical deposition the electrode was removed from the cell and dried at 100° C for 10 min to remove water. Electrochemical deposition was done initially under galvanostatic conditions with the applied current density of 30 - 60 A per square foot, and then changed to potentiostatic conditions after achieving a required film thickness. 

There are some differences in the observed dependence of sulfur poisoning behavior on cell current or voltage. For cell testing carried out under the galvanostatic condition, Singhal et al. [59] reported that the relative power output drop caused by exposure to 10 ppm H2S increased from 10.3 to 15.6% when the cell current density increased from 160 to 250 mA/cm2 at 1000°C. Similarly, Waldbillig et al. [65] also reported that when a hydrogen fuel with 1 ppm H2S was used, the relative drop in cell power output was 6.5, 9.8, and 11.8% for a constant cell current density of 250, 500, and 990 mA/cm2, respectively at 750°C. Xia and Birss [74] indicated that the relative cell power output drop caused by 10 ppm H2S increased from 19 to 56% when the current density increased from 130 to 400 mA/cm2 at 800°C. 

Under galvanostatic conditions in 10% acetic acid the thickness D of the anodic oxide is found to depend on anodization time t according to ... 

Electropolishing under galvanostatic conditions can be used to remove bulk silicon in a well-defined manner. This can for example be used to profile doping density or diffusion length versus the thickness of the sample, as discussed in Sections 10.2 and 10.3. The thickness D of the removed silicon layer can be calculated from the applied current density J, the anodization time t, the dissolution valence nv, the atomic density of silicon Nsi and the elementary charge e. 

The opposite conclusion was reported by Lin et al., who used a three-electrode configuration to study the electrode polarization of the MCMB anode and LiCo02 cathode under galvanostatic conditions. They found that in all cases the polarization at the MCMB anode surface far outweighs that at the cathode to such an extent that the potential profile... 

Cd/solution interface under galvanostatic conditions was carried out. 

The b.v.p. (5.5.1)-(5.5.3) again stands for galvanostatic conditions, with the electric current density... 

Figure 11-19. Ifemporal instabilities of the Ag/AgI interface under anodic load and galvanostatic conditions. T= 260 °C. This plot represents a) the periodic voltage drop across the interface and h) the change in coordinate of the pulsating receding interface [J. Janek, S. Majoni (1994)).

These results are, in some sense, consistent with those of Pierre et. al.[3]. These authors showed that glyoxal electrolysis under galvanostatic conditions (1 A dm 2) on platinum in perchloric acid medium leads to 39% of GA, the potential applied between the two electrodes being in the range of 2 -6 V/RHE. 

Two cubic meters of a nonbiodegradable organic industrial waste water with a COD of 10 kg/m3 and a TOC of 5 kg/m3 are to be pretreated (before the biological treatment) by anodic oxidation under galvanostatic conditions (i = 1 kA/m2) using a filter press electrochemical reactor with a 20 m2 anode surface area. Consider that ... 

In some experiments the WE is grounded and the potential of the CE is controlled such that the potentiostatic or the galvanostatic constraint is fulfilled. This problem is completely equivalent, and thus everything we discuss here about the global coupling under potentiostatic or galvanostatic conditions holds also in that case. 

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