Oxygen reduction process

Dissolved oxygen reduction process Corrosion processes governed by this cathode reaction might be expected to be wholly controlled by concentration polarisation because of the low solubility of oxygen, especially in concentrated salt solution. The effect of temperature increase is complex in that the diffusivity of oxygen molecules increases, but solubility decreases. Data are scarce for these effects but the net mass transport of oxygen should increase with temperature until a maximum is reached (estimated at about 80°C) when the concentration falls as the boiling point is approached. Thus the corrosion rate should attain a maximum at 80°C and then decrease with further increase in temperature. 

With respect to non-noble and non-Ru catalysts, transition metal chalcogenides with spinel and pyrite structures have been investigated and shown that these can also be active to oxygen reduction processes. The motivation in the present case is that chalcogen addition might enhance the stability and activity toward the ORR... 

The above experimental data (Figs. 1 and 2) allow us to estimate the possibility for taking place the oxygen reduction process on PANI catalyst. If the special procedure is not taken to withdraw oxygen out of solution, PANI electrode in 1 M HC1 usually demonstrates a potential of about 0.6 V (SHE). In compliance with the Fig. 1 the position of the reduction peak might be at 0. 28 V. From the data of the standard potentials for the following reaction ... 

Bagotzky, V.S. et al., Electrocatalysis of the oxygen reduction process on metal chelates in acid electrolyte, J. Power Sources, 2, 233, 1977. 

Reaction (18) represents the oxygen reduction process in acidic solution, the reversible potential then being +1.23 V. This leads to a reversible cell voltage of 0.2 V. The theoretical energy usage per tonne of chlorine in this way is unbeatable 160 kWh. 

Under most common DMFC operation conditions, the oxygen reduction process is under interfacial kinetics control and the methanol oxidation process is determined by the methanol flux across the membrane,. /crossover, (Eqs 59-61). The increase in cathode overpotential is therefore be given by... 

This rather simple experiment demonstrates quite clearly the poisoning of the oxygen reduction process by copper. Incidentally, Cu(II) is a rather common impurity in distilled water and mineral acids, and this experiment demonstrates that underpotential deposition of a monolayer of copper from solutions containing as little as 1 ppm Cu can drastically affect the behavior of a platinum electrode. Adsorption of small amounts of other impurities (i.e., organic molecules) can also have an effect on solid-electrode behavior. Thus, electrochemical experiments often require making great efforts to establish and maintain solution purity. 

Because of the ready access of atmospheric oxygen to a metal surface exposed to a thin liquid layer, the most common cathode reaction (see Chapter 1, Volume 4) for metals exposed to a thin aqueous phase is the oxygen-reduction process (see Chapter 1, Volume 4) ... 

These IMPs of technical alloys, which are covered by electric conducting oxides, act as local cathodes for the oxygen reduction process in the tail (Fig. 36a-c). 

Another illustration of the displacement of the electrochemical interface can be found in a recent study reported by Michalik and Rohwerder [42], They were able to locate the oxygen reduction process on a metal-polymer system using an isotopic marker ( 02). The reduction of heavy oxygen will create anions which can be recognized by mass... 

Yokokawa H (2012), Thermodynamic and SIMS analyses on the role of proton/water in oxygen reduction process and related degradations in solid oxide fuel cells. Solid State Ionics 225 6-17... 

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