Electrochemical behaviour of uranium at a tripolyphosphate modified ITO electrode

Abstract

UO₂²⁺ binds to the surface of a tripolyphosphate modified mesoporous indium tin-doped oxide electrode (nanoITO|P₃). Electrochemical studies reveal that nITO|P₃ electrodes catalyze the 2-electron interconversion between UO₂²⁺ and U⁴⁺ with the P₃-ligand assisting in the rate-limiting proton-coupled reduction of U(V) to U(IV), based on the kinetic isotope effect (1.8). Product composition between nITO|P₃(U⁴⁺) and surface adsorbed UO₂ can be controlled by adjusting the proton concentration and/or scan rate in voltammograms. These studies with uranium suggest that nITO|P₃ electrodes are good candidates for redox transformations with other actinides including neptunium, plutonium, and americium.