Oxygen evolution potential

Silver reduces the oxygen evolution potential at the anode, which reduces the rate of corrosion and decreases lead contamination of the cathode. Lead—antimony—silver alloy anodes are used for the production of thin copper foil for use in electronics. Lead—silver (2 wt %), lead—silver (1 wt %)—tin (1 wt %), and lead—antimony (6 wt %)—silver (1—2 wt %) alloys ate used as anodes in cathodic protection of steel pipes and stmctures in fresh, brackish, or seawater. The lead dioxide layer is not only conductive, but also resists decomposition in chloride environments. Silver-free alloys rapidly become passivated and scale badly in seawater. Silver is also added to the positive grids of lead—acid batteries in small amounts (0.005—0.05 wt %) to reduce the rate of corrosion. 

According to Sato et al.,6,9 the barrier-layer thickness is about 1.5 to 1.8 nm V-1, and increases to 3 nm around the oxygen-evolution potential. In Fig. 5, the scale of the electrode potential, Vrhe, is that of the reversible hydrogen electrode (RHE) in the same solution. The electrode potentials extrapolated from the linear plots of the potentials against the film thickness suggested that the potential corresponding to the barrier thickness equal to zero is almost equal to 0.0 V on the RHE scale, independent of the pH of the solution, and approximately agrees with the equilibrium potential for the oxide film formation of Fe or Fe. Therefore it is concluded that the anodic overpotential AE applied from the equilibrium potential to form the oxide film is almost entirely loaded with the barrier portion. 

Thus, the ability of the holes and electrons to bring about redox chemistry can be controlled by changes in pH which ensure that the CB and VB straddle the hydrogen and oxygen evolution potentials. 

Allowing for the overvoltage (0.6 volt) the oxygen evolution potential resulting from the discharge of OH- ions is 0.81 0.6 = 1.41 volt and hence discharge of chloride ions and the formation of chlorine... 

The gas diffusion electrodes/gas-evolving electrodes dispense at least on the side of the oxygen anode with activated carbon, because at oxygen evolution potentials the carbon is subject to rapid oxidation. 

Adipodinitrile is an intermediate for hexamethylenediamine, the amine component of nylon 66. The electrochemical process is economically superior to the synthesis of adipodinitrile from cyclohexanone. Today, it essentially competes with the addition reaction of HCN to butadiene. The total capacity of the electrochemical ADN synthesis is currently about 250,000 tonnes/year. The process is industrially fully developed. Recent work 34 347) is aimed at reducing the oxygen evolution potential at the anode in order to save further energy. 

The oxygen evolution potentials in H2S04 of the most extensively investigated anode materials are compared in Table 2.1. 

The radius of Ru atom is in the middle of that of Sn atom and Ti atom. The three elements can form stabilized solid solution during thermal oxidation and it can resist the formation of nonconductive Ti02. That is the reason why Sn02 electrode with interlayer processes longer service life. Ru02 coating has low oxygen evolution potential, which will result in low electrocatalytic... 

In comparison with the ionic solid corrosion discussed earlier, it is also worth noting that nickel ion transfer from the film into the solution is assumed to control the transpassive nickel dissolution whose rate increases with increasing interfacial potential. We may also see that the rate-determining process changes from the metal ion transfer to the oxide ion transfer near the oxygen evolution potential, beyond which the dissolution rate of the transpassive oxide film decreases with increasing interfacial potential, AH. 

Electrode Preparation. Pt electrodes were polished with alumina polishing powder (1, 0.3, and 0.05 xm) to a mirror finish and cleaned electrochemically by cycling the potential between hydrogen and oxygen evolution potentials in 1-M... 

Fig. 6.4 Efb versus pH for p-GaPN and for a p-GaPN tandem. Both materials show Nemstian behavior. The desired fb for n-type materials (not shown) should be above the solid line for the hydrogen evolution potential to enable majority electron carriers to drive the HER. Similarly, the fb for p-type materials (shown here) should be below the dashed line for the oxygen evolution potential to enable majority hole carriers to drive the OER...

The most important requiranent when selecting photocatalyst materials is the band positions relative to hydrogen and oxygen evolution potentials. The CB and VB edges must straddle the and evolution potentials (the theoretical gap is 1.23 eV),... 

Epa = Passive potential Ecorr = Corrosion potential Eo3 = Oxygen evolution potential Epp = Primary passive potential Ep = Pitting potential... 

The results showed that the end charging potential of the nickel electrodes with flaky rare earth oxides were higher than that without rare earth oxide additives, but lower than that with normal rare earth oxide additives. In summary, flaky rare earth oxides increased the oxygen evolution potential and improved the reversibility of nickel electrodes (109). 

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