Catalytic electrode thick-film oxygen

Thick film oxygen sensor with catalytic electrode (when 1-0). Substituting 1=0 into Equation 20 yields... 

A typical example includes the yttria-stabilized-zirconia-based high-temperature potentiometric oxygen sensor which is widely used in automotive applications. Platinum thick films are applied, forming both the cathode and anode of the sensor. The thick electrode has a porous structure which provides a larger electrode surface area compared to non-porous structures. For current measurement, a porous electrode is desirable since it leads to a larger current output. If the metallic film serves as the electrocatalyst, a porous structure is also desirable, for it provides more catalytic active sites. On the other hand, electrodes formed by the thick-film technique do not have an exact, identical... 

Due to its electronic conductivity, polypyrrole can be grown to considerable thickness. It also constitutes, by itself, as a film on platinum or gold, a new type of electrode surface that exhibits catalytic activity in the electrochemical oxidation of ascorbic acid and dopamine in the reversible redox reactions of hydroquinones and the reduction of molecular oxygen iV-substituted pyrroles are excellent... 

The third cause of passivation is the destruction of solvent immediately on the electrode surface. Such a mechanism is characteristic for a catalytically active metal — platinum. At cathodic polarization of a platinum electrode in well-purified hexamethylphosphotriamide solution of lithium perchlorate an organic film is formed this film contains nitrogen, phosphorus, carbon, and oxygen i.e., the elements forming the solvent molecule. In an ill-purified hexamethylphosphotriamide solution of sodium perchlorate the film formed contains sodium, chlorine, oxygen, and carbon, the film thickness may exceed 20-30 A. The formation of the film from the products of hexamethylphosphotriamide polymerization and destruction is suspected to be the reason for the scattering of the data obtained by different authors and presented in Table 7. 

Similarly, octaethylporphyrin iron (lll)-(r-bonded pyrrole [(OEP)FePy], either adsorbed on a glassy carbon electrode, or buried in a polypyrrole film of different thickness (from 0.9 to 60 pm), deposited on a GC electrode, displays an excellent activity towards oxygen reduction leading to water production efficiencies of nearly 90% [150]. These [(OEP)FePy] electrodes buried into a PPy film are remarkably stable leading to a catalytic activity similar to that obtained with platinum electrodes and limited by the diffusion of dioxygen in the solution phase. 

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