ORIGINAL RESEARCH article
Front. Nucl. Eng.
Sec. Nuclear Materials
Volume 4 - 2025 | doi: 10.3389/fnuen.2025.1639874
This article is part of the Research TopicAnalytical Methods in Nuclear ForensicsView all articles
Hydrodynamic Characterization of the Redox Chemistry of Crown-Encapsulated Uranyl Complexes
Provisionally accepted
Alexander Ervin1
James Blakemore2*- 1The University of Kansas, Lawrence, United States
- 2University of Kansas, Lawrence, United States
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The redox properties of actinide-containing species strongly influence their reactivity, speciation, and interfacial behavior, but the experimental quantification of the electrochemical characteristics of molecular actinide complexes in nonaqueous media has not received the attention it deserves. Here, results from hydrodynamic methods and electrochemical simulations of U(VI)/U(V) redox are reported, including quantification of heterogeneous electron-transfer kinetics and estimation of chemical reversibility of U(VI)/U(V) interconversion at electrodes in acetonitrile-based electrolyte. The complexes investigated are recently reported U(VI) and U(V) complexes in which the uranyl ion (UO2n+) is encapsulated in a macrocyclic 18-crown-6-like moiety templated by a Pt(II) center. These complexes feature the most positive value UVI/UV reduction potential yet reported and are thus particularly relevant to study of facile U(V) generation from U(VI) precursors as well as uranium electroanalysis. Rotating disk electrode (RDE) studies have been used to quantify the diffusion coefficients of the U(VI) and U(V) complexes, and standard heterogeneous electron transfer rate constants (k0) for the redox have been determined using a conventional Koutecký-Levich analysis. Rotating ring-disk electrode (RRDE) studies have been used to directly interrogate the chemical reversibility of U(VI)-U(V) interconversion, confirming that reduction of the U(VI) complex at an Au disk is associated with formation of the U(V) analogue that can be readily re-oxidized at a Pt ring under hydrodynamic (rotating) conditions. Because measurements of the type reported here are generally associated with current flows that are larger than those found in corresponding quiescent (unstirred) conditions, our findings suggest that hydrodynamic methods could be advantageous for design of electroanalytical approaches to detection of actinide species and study of their redox properties.
Keywords: actinides, Crown Ethers, cyclic voltammetry, rotating electrodes, reversibility
Received: 02 Jun 2025; Accepted: 30 Jun 2025.
Copyright: © 2025 Ervin and Blakemore. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: James Blakemore, University of Kansas, Lawrence, United States
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