Studies of Ruthenium‐Oxy Species in Basic Solutions by Cyclic Voltammetry

Ruthenium (VI) solutions in alkaline media have been investigated by cyclic voltammetry using platinum and ruthenium dioxide electrodes. Four pairs of peaks were observed. The oxidation states of the electrolysis products were evaluated by coulometry and absorption spectra. The first and second pairs of peaks correspond, respectively, to the oxidation reduction of Ru(VIII)/ Ru(VII) and Ru(VII)/Ru(VI) with a catalytic reaction. The third pair shows reduction of Ru(VI) to Ru(IV) with a following reaction giving ruthenium dioxide. The electron transfer product is postulated as . The last or most cathodic pair revealed a reduction peak composed of two waves. The first is from the reduction of the electrode surface oxide layer or adsorbed oxygen and the second, the reduction of Ru(IV) to Ru(III). The corresponding pairs of peaks are also observed from ruthenium dioxide electrodes in sodium hydroxide solutions.