Voltammetric study of polycrystalline rhodium in alkaline solutions at different temperatures

The voltammetric behaviour of rhodium in 1 M KOH in the 273–353 K range was investigated paying particular attention to the different stages of the overall reaction, involving the successive electroformation of RhOH, RhO monolayer, and hydrous Rh oxide layer growth. A redox couple of high reversibility operating within the oxide structure can be detected at potentials close to the threshold potential of the oxygen evolution reaction. Hydrous Rh oxide layer growth and ageing are interpreted in terms of a place exchange mechanism. Data obtained in the present work are compared to results obtained previously with different noble metals in acid and alkaline solutions.