Study of Magnetic Effects on Lanthanide Electrochemistry

Lanthanide isotopes are produced during fission of ²³⁵U, most of which decay to stable nonradioactive lanthanide elements in a relatively short amount of time¹.  The lanthanide elements can be difficult to separate from each other in solution because they have extremely similar properties, including masses, ionic radii, oxidation states, and standard potentials². Present lanthanide detection and separation methods are tedious and time-consuming.

Lanthanides do have different numbers of unpaired 4f electrons, resulting in distinct magnetic properties. Here, Boron-doped diamond (BDD) electrodes are magnetically modified to exploit this difference. Recent data suggests that modification of electrodes with chemically inert magnetic particles enhances current for electrochemical reactions³. The effect scales with the magnetic moment of the redox species and the number of unpaired electrons.

Electrochemically, lanthanide analysis is limited by their standard potentials (in the range of -1.99 and -3.90 V vs NHE⁴). These potentials fall outside of the potential window of common electrolyte solutions. For example, in aqueous solutions at platinum, the potential window is limited between +1.3 and -0.7 V vs NHE by solvent electrolysis⁵. Previously, researchers have resorted to mercury drop electrodes or chemically modified carbon paste electrodes to look at lanthanide compounds². BDD electrodes offer a safer, simpler alternative; the overpotentials for hydrogen and oxygen occur at very extreme potentials on BDD compared to other materials such as glassy carbon, platinum, and gold. This allows for a wider potential window for investigation of lanthanide compounds. Here, nonaqueous lanthanide solutions are investigated at a BDD electrode⁶.

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2.         Schumacher, P. D.; Doyle, J. L.; Schenk, J. O.; Clark, S. B., Rev Anal Chem 2013, 32 (2), 159-171.

3.         Lee, G. G. W.; Leddy, J.; Minteer, S. D. Chem Commun 2012, 48 (98), 11972-11974.

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6.         Martin, H. B.; Argoitia, A.; Landau, U.; Anderson, A. B.; Angus, J. C. J Electrochem Soc 1996, 143 (6), L133-L136.