Polarization curves recording

The current is recorded as a function of time. Since the potential also varies with time, the results are usually reported as the potential dependence of current, or plots of i vs. E (Fig.12.7), hence the name voltammetry. Curve 1 in Fig. 12.7 shows schematically the polarization curve recorded for an electrochemical reaction under steady-state conditions, and curve 2 shows the corresponding kinetic current 4 (the current in the absence of concentration changes). Unless the potential scan rate v is very low, there is no time for attainment of the steady state, and the reactant surface concentration will be higher than it would be in the steady state. For this reason the... 

FIGURE 15.9 Anodic polarization curves recorded at a platinum electrode in the region of high anodic potentials in the presence of acetate ions (1) total current (2) partial current of oxygen evolution (3) partial current of oxidation of adsorbed species. 

Figure 1.23 j(E) polarization curves recorded at a rotation rate 2 = 2500 rpm in an 02-saturated 0.1 M NaOH electrolyte (T=20°C, v = 5 mVs ) for (dashed line) 20wt%Ag/C and (solid line) 20wt% Pt/C. Ag/C catalyst was prepared according to the water-in-oil microemulsion method, whereas Pt/C catalyst was prepared using the Bonnemann method. 

Fig. 13. Polarization curves (recorded at 1 mV s ) corresponding to the photoanodic oxidation and the cathodic reduction of hydrogen peroxide at a polycrystalline Ti02-film electrode. Curve a is for an illuminated (X > 335 nm) and curve b for an unilluminated electrode (see text). Measurements performed in a deaerated 0.1 MNaOH/10" M H2O2 solution...

Figure 3.15 (A) Dynamic polarization curves obtained with a carbon disk (A = 0.46cm2, top) of a Pt carbon RRDE (N = 0.175) and corresponding Pt ring (bottom) currents recorded in 1.5 mM Co(lll)(cyclam) in 0.5 M HCI04aqueoussolutionsintheabsence (curve 1) and in the presence of 02 at 900 rpm (curve 2), that is, Jc0(cyclam)/o2 small, for Ering = 0.6 (curve 3) and 1.0V versus SSCE (curve 4) both in the presence of 02. (B) Corresponding dynamic polarization curves recorded with the same...

Figure 3.47 Upper panels steady state polarization curves recorded with a Pt OPG RRDE (co=100rpm) for coatings (6 x 10-8 mol citT2) of FeTPP (A), FePPIX (B) and FeTPyP (C) (see solid circles) deposited on the OPG disk in aqueous 02-saturated 0.1 M HCIO4 + 0.1 M NaCI04, where each ofthe points was collected for a freshly prepared coating. The data in empty circles are ring currents recorded...

More recently, Faubert et al. [129] studied in a more systematic fashion the effect of Tp on both the activity and the stability of FeTPP (presumably in its (t-oxo form) and CoTPP dispersed on XC-72 carbon incorporated into a gas diffusion electrode in actual fuel cells. Shown in Figure 3.72A and 3.72B are polarization curves recorded at 50 °C for FeTPP XC-72 and CoTPP XC-72, respectively, pyrolyzed at the specified temperatures, in a Nafion -based fuel cell configuration for which the performance of specimen in the range 700 < Tp < 900 °C was fairly comparable to that of 2% w/w Pt supported on high-area carbon. These same materials also displayed good stability up to about 10 h compared to samples treated at higher and lower Tp under the same conditions (see Figure 3.73A and 3.73B). Also shown for comparison are the results obtained for 2% w/w Pt dispersed in the same carbon. 

Figure 3.72 Polarization curves recorded at 50°C for FeTPP XC-72 (A) and CoTPP XC-72 (B) pyrolyzed at the specified temperatures in a fuel cell configuration. Also shown in dotted lines for comparison are data collected under the same conditions for 2% w/w Pt, supported on high-area carbon (see original reference for details).

The polarization curves recorded on the cylindrical platinum electrodes treated in the same way as the cylindrical copper electrodes in Fig. 24 are shown in Fig. 25. There is not any difference between polarization curves obtained on the copper and platinum substrates. 

The activation-diffusion control of electrodeposition process is a characteristic of metals characterized by the medium exchange current density values and lower hydrogen overpotentials. Copper is the typical representative of this group of metals, and the polarization curve recorded from 0.10 M CUSO4 in 0.50 M H2SO4 is shown in Fig. 1.10a. 

Fig. 8.16 The polarization curves for the electrodeposition of Fe powders from the electrolyte containing 0.1 M FeCl3-h0.2 M Na3C6H507-hl M NH4CI (a) and 0.1 M FeCl2 + 0.2 M Na3C6H507 -t- 1 M NH4CI (b). Inset - the same polarization curves recorded at potentials more positive than —1.0 V versus AglAgCl (Reprinted from Ref. [1] with kind permission from Springer)...

Fig. 22.8 Polarization curves for oxygen evolution on 10 pg/cm Ru and Ir sputter-deposited on Pt-NSTF. OER curve on Pt-NSTF substrate also included, (a) Ruthenium all three consecutive polarization curves for end voltage of 1.45 V and only the first of the three for 1.55 and 1.65 V are presented. Iridium all three consecutive polarization curves Iot end voltage of 1.55 V are presented note that the three curves overlap. Inset comparison of the first polarizatirai curves for 10 pg/cm upper) and 2 pg/cm Ru lower), the line with arrows indicates the linear, Tafel region of the polarization curve, (b) The three crmsecutive polarizations curves for Ru up to 1.5 V. All polarization curves recorded at 2 mV/s in 50-cm MEA under nitrogen/1 % hydrogen, 70 °C, fully saturated. Electrode potentials expressed vs. SHE...

Fig. 1. Polarization curves recorded at 10 mV s for O2 reduction in 02 8aturated 0.5 M H2SO4 onaa)(—)pc-Au,b)( )po-Aa-<-0.3 pNaf electrode.

The polarization curve recorded onto GC electrode from citrate solution is compared with those from sulfate and chloride solutions in Fig. 2.42. Similar polarization curves from all solutions are obtained, except that the current density after the second inflection point for citrate solution is half of that for sulfate and chloride solutions. The (f]j) vs. E dependence recorded in citrate solution is similar to those for sulfate and chloride solutions, being practically constant (20%) in the potential range of current density plateau on the polarization curve 7Ni vs. E. 

It is understood that in the cycling potential range, platinum particles experience the dissolution and redeposition that leads to decrease of surface area and therefore an activity reduction. Diagnostic measurements include the ECSA determination (under H2/N2) and polarization curve recording (by switching to mode)... 

Figure 2. Potentiodynamic polarization curves recorded in aqueous solution of 0.05 mol/1 NaCl of pure aluminium uncoated and spin-coated with TEOS, PTES and PTMS, additional line indicates exemplarily the electrode potential were Jdiss was obtained. OCP open circuit potential (= ). 

Fig. 3. Schematic potentiodynamic polarization curve recorded on a passivating metallic material (Fe-30%Ni alloy) in absence of any sliding Ef = Flade potential, Em = potential at maximum dissolution current Im, Ip = passivation current.

Figure 9.2 shows typical polarization curves recorded in a DAFC with different anodic catalysts. Even with the best recognized catalysts for ethanol... 

Figure 9.2. Polarization curves recorded at 80°C in a DEFC fitted with different anode catalysts.

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