The catalysis of the anodic oxidation of cobalt(II) and manganese(II) by silver(I) in aqueous sulphuric acid

Abstract

It is confirmed that silver(I) is a very effective catalyst for the oxidation of manganese(II) and cobalt(II) at a Pt anode in sulphuric acid media. At the potential of the Ag+−e→Ag2+ oxidation peak, +1.29 V vs. a mercury/mercurous sulphate reference electrode in 40% sulphuric acid, the current efficiencies for the oxidation of cobalt(II) and manganese(II) are high and cyclic voltammetry shows that the current is largely determined by the transport of cobalt(II) or manganese(II) to the surface even when these ions are present in large excess (i.e. the Ag2+/Co2+ and Ag2+/Mn2+ reactions are very fast). It is also shown that by choice of the electrolysis conditions, the major product from the oxidation of manganese(II) can be manganese(III), manganese dioxide or permanganate.