Types of oxide electrode

Oxide materials which are attractive because of their catalytic activity are often employed in the form of finely divided powders of considerable surface area. The history of the material and the preparation technique employed are important aspects to be considered when electrokinetic data are compared. Oxide powders can be hot pressed into sintered pellets, supported, or impregnated, on to carbons of high specific area, and bonded with Teflon or other inert material into composite electrodes. Microporosity of the system may produce an ill-defined surface zone flooded by electrolyte with imprecise ratio of real surface area to geometric cross-section. Sput- 

The technologically important dimensionally stable anodes (DSA) are thermally prepared mixed oxide films supported on an inert substrate, usually Ti, which contain Ru02 as the catalytically active component. These anodes exhibit high performance in the industrial generation of chlorine. 

Finally, optically transparent electrodes comprised of Sn02 or ln203 thin films on glass, quartz, or plastic are widely used to study electrochemical reactions under illumination in solution. Spectral studies of reactants, intermediates, or products can be also performed to gain some molecular insight into electrode kinetics. 

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There is a need to develop new types of oxide electrodes for reactions of technological importance with emphasis on both high electrocatalytic activity and stability. For example, pyrochlore-type oxides, e.g. lead or bismuth ruthenates, have shown excellent catalytic activity for the oxygen evolution and reduction reactions and should be further investigated to elucidate the reasons for such high activity. The long term stability of such ruthenate electrodes is questionable, however. 

More types of oxides used for electrodes of the zirconia-based sensors both enable and encourage more possible combinations. Greater diversity in zirconia structures and types of oxide electrodes leads, in turn, to more incompatibilities in chemical, physical, electrochemical, and mechanical properties. The irony is that the more diversity achieved with advanced solid electrolyte and electrode materials, the bigger the challenges that arise for their joining. Beyond sheer diversity, modem... 

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