Cathode catalyses stability

Iwayama, K Wang, X., "Selective decomposition of nitrogen monoxide to nitrogen in the presence of oxygen on Ru02/Ag(cathode)/yttria-stabilized zirconia/Pd(anode)", Applied Catalysis B Environmental, 19,137 (1998). 

The ratio ARH/ARj (monoalkylation/dialkylation) should depend principally on the electrophilic capability of RX. Thus it has been shown that in the case of t-butyl halides (due to the chemical and electrochemical stability of t-butyl free radical) the yield of mono alkylation is often good. Naturally, aryl sulphones may also be employed in the role of RX-type compounds. Indeed, the t-butylation of pyrene can be performed when reduced cathodically in the presence of CgHjSOjBu-t. Other alkylation reactions are also possible with sulphones possessing an ArS02 moiety bound to a tertiary carbon. In contrast, coupling reactions via redox catalysis do not occur in a good yield with primary and secondary sulphones. This is probably due to the disappearance of the mediator anion radical due to proton transfer from the acidic sulphone. 

Oxygen reduction can be catalyzed by enzymes, and air-breathing cathodes with laccase and bUimbin oxidase as enzymatic catalysts, for example, have been demonstrated [10-15]. Enzymatically catalyzed cathodes avoid many of the problems discussed for platinum and other precious metal catalysts, but they often provide lower power density and Umited stability. Specifically with air-breathing cathodes, enzymes that catalyze oxygen reduction must be immobilized at the tripoint between hydrophilic (H" conductivity), hydrophobic (O2 supply), and conductive (e conductivity) interfaces for effective catalysis (Figure 16.1) (see Chapter 3). 

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