Tungsten, standard reduction potentials

There is a relatively large volume of electrochemical data on americium in molten-salt media, specifically LiCl—KCl eutectic at solid (W, Mo, Ta) and liquid (Cd, Bi) electrodes. Lambertin etal. studied the electrochemical reduction of AmCb in LiCl—KCl at 470 °C at a tungsten working electrode [144]. It was determined from the cyclic voltammetric data that Am(III) is first reduced to Am(II) and subsequently reduced in a second step to Am(0). The voltammetry data were used to estimate the standard potential for the Am(III)/Am(II) couple as —2.84 V versus CI-/CI2 and —2.945 V versus Cl /Cl2 for Am(II)/Am(0). These results are in very good agreement with an earlier study by Fusselman and coauthors [105,145]. They determined standard potentials for the Am(III)/Am(II) couple as —2.83 V versus Cl /Cl2 and —2.852 V versus Cl /Cl2 for the Am(II)/Am(0) couple at 450 °C. More recently Lambertin etal. extended their studies with a report on the stability of Am ions in molten LiCl—KCl in the presence of fluoride ions [146]. They found that Am(III) undergoes a direct three-electron reduction to Am(0) in the presence of fluoride at —2.91 V versus CI-/CI2 without voltammetric evidence... 

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