Redox processes at iron hydroxide layers formed on platinum substrates in alkaline solutions

Abstract

Redox processes taking place at precipitated hydrous iron hydroxide layers chemically formed on platinum substrates in sodium hydroxide solutions are investigated at 25°C. The electrochemical behaviour of these layers depends considerably on the electroreduction level reached in chargedischarge cycles. The accumulation of Fe3O4 during oxidation-reduction cycles can produce an increasing irreversibility of the Fe(II)/Fe(III) redox couple. Data are compared to results obtained with iron hydroxide layers formed by electrochemical and chemical methods on massive iron electrodes. Results are discussed in terms of a composite structure for the iron hydroxide layers.