Effect of U Content on the Activation of H2O on Ce1-xUxO2+δ Surfaces Academic Article uri icon

abstract

  • The Ce-U-O system raises growing interest due to its potential importance for water splitting at low temperatures. The variable possible oxidation states of Ce (Ce3+ and Ce4+) and U (U4+, U5+ and U6+) lead to the formation of point charged defects on the surface. These point charges are active sites for the chemisorption of H2O, which is the rate-determining step for H2 production. In the present work, the interaction of H2O with the surface of Ce1-xUxO2+δ oxides in a wide range of compositions (x=0, 0.1, 0.25, 0.5, 0.75 and 1) is studied through the measurements of adsorption and calorimetric isotherms at room temperature. The oxides’ structure is determined by X-ray Diffraction (XRD) and the charge distribution between the U and Ce cations is inferred from X-ray photo-electron spectroscopy (XPS) measurements. The adsorption thermodynamics is analyzed within the electronic theory of chemisorption on semi-conducting surfaces. Based on this analysis, correlated to the XPS results and to Density Functional ...

publication date

  • January 1, 2018