Electrolyte solutions in liquid ammonia—x. A cyclic voltammetric examination of electron transfer between solvated ruthenium(III) and ruthenium(II) cations, and anodic passivation of platinum electrodes
✍ Scribed by J. Bernard Gill; Michael Hall; Norman Taylor
- Publisher
- Elsevier Science
- Year
- 1988
- Tongue
- English
- Weight
- 564 KB
- Volume
- 33
- Category
- Article
- ISSN
- 0013-4686
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✦ Synopsis
Single electron transfer between the hexammine cations of Ru(III) and Ru(I1) at a Pt metal electrode in liquid ammonia closely follows Nemstian behaviour during the lirst voltammetric cycle if the voltage sweep rate is tow. The redox electrode based on the Ru(III)/Ru(II) couple at a Pt metal surface deviates from voltammetric reversibility as: (i) the voltage ramp rate, (ii) the concentration of Ru(NH& + cation, and (iii) the number of applied voltammetric cycles, are increased. X-ray photoelectron spectra of the surface layer of Pt metal after exposure to anodic potentials in excess of 0.3 V reveal that the Pt metal surface is oxidized in liquid ammonia (electrolytically and in voltammetric cycles) to a gold-coloured compound containing equimolar amounts of Pt(lI) and Pt(IV). These results are discussed in the light of previous contentious reports about the use of H2 gas on Pt as a primary standard electrode for work with liquid ammonia solutions.