Electrocatalytic properties of electrodeposited osmiumстатья
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Дата последнего поиска статьи во внешних источниках: 18 июля 2013 г.
Аннотация: By measuring the potential shifts and also the charging, steady-state polarization, and voltammetric curves, the behavior of osmium electrodeposits (Os/Pt) is studied in acid and alkaline solutions in the presence of methanol, ethanol, propanol, formaldehyde, acetaldehyde, and formic acid. The cathodic shift of the Os/Pt potential upon introducing alcohols is probably due to the oxidation of their molecules by the hydrated lowest oxides of osmium on its surface. During the establishment of the potential upon adding aldehydes and formic acid, both the oxidation and reduction of these substances proceed. Gaseous hydrogen evolves in alkaline solutions of formaldehyde at potentials exceeding the reversible hydrogen potential; this is explained by the secondary processes in the near-electrode layer involving products of electrocatalytic conversions of formaldehyde. As is shown by measuring steady-state polarization curves, in a number of systems at low overvoltages, the electrocatalytic activity of osmium is higher than that of platinum. However, the processes on osmium are inhibited by the emergence of inactive oxygen-containing adsorbate forms. On the whole, electrocatalytic activity of osmium resembles the behavior of ruthenium. The high activity of osmium explains its role as the additive in the alloys with other platinum metals, which ensures the tolerance of catalysts to carbon monoxide and some other catalytic poisons. ? 1999 MAEe cyrillic signK "Hay?a/Interperiodica".
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