Surface electrochemistry of UO2 in dilute alkaline hydrogen peroxide solutions

Goldik, J.S.; Nesbitt, H.W.; Noël, James J.; Shoesmith, David W.

doi:10.1016/j.electacta.2003.11.029

Cited by 54 publications

(59 citation statements)

References 25 publications

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“…7 also shows that SIMFUEL exhibits less surface oxidation than undoped UO 2 despite its equivalent specific alpha activity. This can be attributed to the SIMFUEL additives, including rare earth elements, which stabilize the UO 2 matrix with respect to oxidation [26].…”

Section: Pellet Surface Condition After Annealing and Storage In Air mentioning

confidence: 98%

“…Although uranium at oxidation state (V) is not stable in solution (disproportionation), ab initio calculations showed that it is a necessary step in the oxidation of U IV to U VI for UO 2+x oxides, especially with low surface oxygen coverage [24]. Oxidation state (V) has already been reported in the decomposition of XPS spectra for electrochemically oxidized UO 2 samples [25][26][27]. For the lower activity samples the U 4f 7/2 spectra are shifted toward low energies (380-381 eV), i.e.…”

Section: Pellet Surface Condition After Annealing and Storage In Air mentioning

confidence: 98%

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Radiolytic oxidation of UO2 pellets doped with alpha-emitters (238/239Pu)

Muzeau

Jégou

Delaunay

et al. 2009

Journal of Alloys and Compounds

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Section: Pellet Surface Condition After Annealing and Storage In Air mentioning

confidence: 98%

Section: Pellet Surface Condition After Annealing and Storage In Air mentioning

confidence: 98%

Radiolytic oxidation of UO2 pellets doped with alpha-emitters (238/239Pu)

Muzeau

Jégou

Delaunay

et al. 2009

Journal of Alloys and Compounds

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“…The cell was placed into a grounded Faraday cage to minimize external noise. During cyclic voltammetric (CV) measurements, the current interrupt method was used to compensate for the electrode and solution resistances, which are estimated to be ∼50 to 60 cm from previous electrochemical impedance spectroscopic measurements [20].…”

Section: Electrochemical Cell and Equipmentmentioning

confidence: 99%

“…The influence of H 2 O 2 on fuel corrosion has been extensively studied [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] and much of the early literature has been reviewed [5,24]. The cathodic reduction of H 2 O 2 on UO 2 surfaces was found to proceed via a coupled chemical-electrochemical process in which H 2 O 2 chemically creates U IV -U V donor-acceptor sites on the UO 2 surface…”

Section: Introductionmentioning

confidence: 99%

“…However, under neutral to alkaline conditions, when the solubility of U VI (as UO 2 2+ ) is low [25,26], corrosion is blocked at sufficiently high H 2 O 2 concentrations by the formation of insulating U VI surface deposits [5,10,20]. The nature of these deposits varies with peroxide concentration, with schoepite ((UO 2 ) 8 O 2 (OH) 12 ·12H 2 O) dominating at lower concentrations (≤10 −4 mol/L) and the uranyl peroxide hydrate, studtite (UO 4 ·4H 2 O) at higher concentrations [15,16,27].…”

Section: Introductionmentioning

confidence: 99%

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The electrochemical reduction of hydrogen peroxide on uranium dioxide under intermediate pH to acidic conditions

Keech

Noel

Shoesmith

2008

Electrochimica Acta

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XPS determination of uranium oxidation states

Ilton

Bagus

2011

Surface & Interface Analysis

217

118

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This contribution is both a review of different aspects of X-ray photoelectron spectroscopy that can help one determine U oxidation states and a personal perspective on how to effectively model the X-ray photoelectron spectroscopy of complicated mixed-valence U phases. After a discussion of the valence band, the focus lingers on the U4f region, where the use of binding energies, satellite structures, and peak shapes is discussed in some detail. Binding energies were shown to be very dependent on composition/structure and consequently unreliable guides to oxidation state, particularly where assignment of composition is difficult. Likewise, the spin orbit split 4f 7/2 and 4f 5/2 peak shapes do not carry significant information on oxidation states. In contrast, both satellite-primary peak binding energy separations, as well as intensities to a lesser extent, are relatively insensitive to composition/structure within the oxide-hydroxide-hydrate system and can be used to both identify and help quantify U oxidation states in mixed valence phases. An example of the usefulness of the satellite structure in constraining the interpretation of a complex multivalence U compound is given. Copyright © 2011 John Wiley & Sons, Ltd.Keywords: XPS; uranium; oxidation states IntroductionOne of the great strengths of X-ray photoelectron spectroscopy ( XPS) is its ability to elucidate the valence state of a wide range of elements at the near-surface of materials. Although many features of interest concern bulk properties, it is the surface and the near-surface that has immediate contact with its surroundings and consequently mediates most reactions. With the renewed interest in nuclear energy, characterizing the surface composition and chemical state of actinide-containing materials is important for both industrial applications and understanding the fate and transport of actinides in the environment. This perspective article is focused on uranium as the data set is by far the most comprehensive of all the actinides where an appreciable literature on the XPS of U compounds dates back to the beginnings of the commercialization of XPS in the 1970s. For an early paper on the XPS of a broad range of actinide oxides we refer the reader to Veal et al.[1] A basic understanding of XPS principles is assumed throughout and will not be reviewed.On one level, determining oxidation states with XPS would appear to be a simple exercise of comparing the binding energies (BEs) of core levels to well characterized standards; so why bother? However, interpreting the oxidation states of samples with mixed valence, unknown structures, and complicated or different compositions can pose a challenge, as with any analytical technique. In fact, composition can strongly affect uranium core-level BEs and potentially confuse the determination of oxidation states. For example, perhaps one is working in an oxidizing system and only expects U(VI), yet the U4f 7/2 line has a peak at 382.0 eV and a shoulder at 380.5 eV. Does the shoulder represent a reduced species, po...

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Surface electrochemistry of UO2 in dilute alkaline hydrogen peroxide solutions

Cited by 54 publications

References 25 publications

Radiolytic oxidation of UO2 pellets doped with alpha-emitters (238/239Pu)

Radiolytic oxidation of UO2 pellets doped with alpha-emitters (238/239Pu)

The electrochemical reduction of hydrogen peroxide on uranium dioxide under intermediate pH to acidic conditions

XPS determination of uranium oxidation states

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