Electrochemiluminescence in the reduction of uranyl ions on platinum in sulfuric acid solutions

Electrochemiluminescence (ECL) in the reduction of uranyl ions in sulfuric solutions in the presence of XeO3 on the platinum cathode was observed and studied. At early stages of electrolysis (at 0.34 < ψ < 0.62 V), the chemiluminescence reaction U5 + XeO3 contributes mainly to the luminescence intensity, whereas at ψ < 0.32 V, the contribution of the reaction U4 + XeO3 predominates. The transfer coefficient for the primary electrochemical stage, formation of U5, was estimated: α = 0.46-0.54. The high sensitivity of ECL to the state of the electrode surface is explained by the fact that the reduction of U6 occurs on the most active sites only. The background photoreactions, among which U5 + O2 and U5 + H2O2 can be distinguished, were considered, and their contributions to ECL were determined