Four kinds of sintered ZrB
2 solids-thermal impulse resistive TR, antifrictional HZ, oxidation resistive OR, and corrosion resistive CR, were studied in aqueous and propylene carbonate solutions at room temperature for the purpose of applying them to solid electrodes for electrolysis of some kinds of redox systems and of electroanalysis. As in the case of glassy carbon electrodes very small residual currents were observed on the anode branches of cyclic voltammograms for TR and HZ. And the redox systems [Fe(CN)
6]
3-/[Fe(CN)
6]
4-, I
2/I
-, and quinone/hydroquinone showed electrochemically reversible redox current waves at the electrodes. On the other hand at electrodes OR and CR, large residual current waves over 1.2mA/cm
2 height were observed in the potential range 0-0.6V vs. Ag/AgCl, Cl
-, which may have been caused by oxidation of sintering reagent SiC of the solid. All of the electrodes used here were very inert in alkaline solutions of pH of 12 or higher, due to being covered with the reaction product Na
2SiO
3 layer. In propylene carbonate solution, TR and HZ behaved as in aqueous solution, but OR and CR seemed to have a high resistant film on the surface which allowed charging and discharging current across itself.
It is suggested that studies of the electrocatalytic characteristics of these materials and of characteristics as an electrode for electrolysis at high temperatures at which the inherent properties of ZrB
2 are fully utilized must be carried out for more redox systems than were studied here.
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