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Published online by Cambridge University Press: 17 March 2011
The kinetics of H2O2 reduction have been studied in slightly alkaline (pH 9.7 NaCl) solution on 1.5 at.% SIMFUEL. Using cyclic voltammetric techniques, we have shown that the cathodic reduction of H2O2 is kinetically facile on UIVUVO2+x surfaces. Carbonate ions are found to have a significant effect on the kinetics of H2O2 reduction. Suppression of the reaction rate is observed at very cathodic potentials, and has been attributed to a competition between carbonate and hydrogen peroxide for catalytic sites on the electrode surface. A small enhancement of the reduction current occurs between –200 and +100 mV vs. SCE, which appears to be due to a surface adsorbed carbonate complex. The large values of the Tafel slopes for H2O2 reduction have been interpreted in terms of a chemical-electrochemical mechanism involving surface UV species. The results are discussed in terms of a mixed potential model for the prediction of nuclear fuel dissolution rates under permanent disposal conditions.