Oxygen evolution reaction solutions

Kobussen et al. [281 285] have carried out a detailed study of the oxygen evolution reaction on La05Ba(lr)CoO3 principally in strongly alkaline solution. Following reaction order studies [282], impedance measurements [283, 286], and overpotential decay behavior studies [287], a modified Krasil -shchikov [288] mechanism was proposed for oxygen evolution on this oxide catalyst. The first three steps of this mechanism are similar to eqns. (52)-(55) written as equilibrium processes. An alternative to step reaction (54) was... 

The oxygen evolution reaction (OER) has been investigated at both BDD and BDD/Ir02 electrodes, using perchloric and sulfuric acid aqueous test solutions. 

Fig. 14. Rotating (45 Hz) ruthenium dioxide/titanium dioxide electrode (35% w/w ruthenium dioxide) in 0.1 M NaCl solution, (a) Standard rate constant-potential curve for the chloride oxidation reaction [reaction (1)] assuming a constant Tafel slope of 70mV, Da — 5 x 10 6cm s 1, Z)cl2 = 7 x 10 6cm s 1, E[ = 1050mV SCE, and R = 2.2ohm cm2. The characteristics of the oxygen evolution reaction [reaction (2)] with a Tafel slope of 200 mV were chosen to be fej, = 1 x 10 8 cm s, EH = 1257 mV SCE and Dq2 = 1 x 10 5 cm2 s 1, (b) Common experimental and calculated current-potential curve using parameters of Fig. 14(a). The broken curve refers to the calculated "reversible curve.

The oxygen evolution reaction occurs at the anodic layer solution interface, whereby oxygen atoms are obtained as intermediate products. 

Polarization curves of the oxygen evolution reaction and the corrosion reaction in the cases when Ag is introduced in the solution or in the metal [121]. 

What is the effect of silver on the anodic corrosion of lead It is revealed hy the rate of oxidation of the metal expressed in current density units (Fig. 2.45). Let us consider the case when the polarization is carried out at a constant potential (e.g., 1500 mV). When Ag ions are introduced into the solution, the oxygen over-voltage decreases. When silver is alloyed in the metal, a weaker effect on the rate of oxygen evolution is observed, but the corrosion rate of the lead—silver alloy is considerably reduced. Hence, the introduction of silver by both methods accelerates the oxygen evolution reaction, but it affects differently the anodic corrosion of the metal. 

It is important to determine the conductivity and flat-band potential ( ft) of a photoelectrode before carrying out any photoelectrochemical experiments. These properties help to elucidate the band structure of a semiconductor which ultimately determines its ability to drive efficient water splitting. Photoanodes (n-type conductivity) drive the oxygen evolution reaction (OER) at the electrode-electrolyte interface, while photocathodes (p-type conductivity) drive the hydrogen evolution reaction (HER). The conductivity type is determined from the direction of the shift in the open circuit potential upon illumination. Illuminating the electrode surface will shift the Fermi level of the bulk (measured potential) towards more anodic potentials for a p-type material and towards more cathodic potentials for a n-type material. The conductivity type is also used to determine the potential ranges for three-electrode j-V measurements (see section Three-Electrode J-V and Photocurrent Onset ) and type of suitable electrolyte solutions (see section Cell Setup and Connections for Three- and Two-Electrode Configurations ) used for the electrochemical analyses. 

Electrochemical Oxygen Evolution. Thermodynamically, the oxygen evolution reaction is favoured over the chlorine evolution reaction in aqueous solutions because the standard reversible potential is 1.23 V for the oxygen evolution reaction and 1.35 V for the chlorine evolution reaction. However, because of the slow kinetics of the oxygen evolution... 

Anode performance depends on the brine quality and the operating parameters such as pH, current density, NaCl concentration, and NaOH concentration (in diaphragm and membrane cells). The contribution of the anode to the cell inefficiency, as mentioned in Section 4.4, is directly related to the losses arising from the oxygen evolution reaction, and indirectly by chlorate formation. Thus, as the %02 increases, the pH at the anode-solution interface decreases, and hence, the amount of chlorate formed will decrease as the bulk pH is lowered. The amount of O2 generated at the anode is a function of the current density, pH, the composition and surface area of the anode coating, and the salt concentration. 

---