Oxygen exchange materials

Scheffe, J.R. and Steinfeld, A. (2014) Oxygen exchange materials for solar thermochemical splitting of H2O and CO2 a review. Mater. Today, 17 (7), 341-348. 

Oxygen exchange is not consistent with the one-step mechanism, which provides no way for it to happen. Oxygen exchange is consistent with a two-step mechanism in which intermediate I is not only formed, but partly reverts into starting material and partly is converted (probably via the neutral species II) into III—an intermediate that is equivalent to I except for the position of the label. If all this is so, the reversion of intermediate III into starting material yields ester that has lost its 0. 

B.C.H. Steele, Isotopic oxygen exchange and optimisation of SOFC cathode materials, in F.W. Poulsen, J.J. Bentzen, T. Jacobsen, E. Skou and M.J.L. 0stergSrd (Eds.), High Temperature Electrochemical Behaviour of Fast Ion and Mixed Conductors. Riso National Laboratory, Denmark, 1993, pp. 423-430. 

B. A. Boukamp, K.J. de Vries, A.J. Burggraaf, Surface oxygen exchange in bismuth oxide based materials, in J. Nowotny, W. Weppner (Eds.), Non-Stoichiometric Compounds, Surfaces, Grain Boundaries and Structural Deffcts, Kluwer, Dordrecht, 1989, pp. 299-309. 

The objectives of this work are to study the influence of gold particles on the properties of typical catalyst supports, namely MgO and TiO. Gold has been chosen because of its relatively low catalytic activity except for oxygen transfer reactions (4). MgO, an insulator, and TiO, a semiconducting material, are widely used as catalyst supports, and for both of them metal-support interactions have been reported in the literature. Our study places main emphasis on the role of gold on thermal stability, phase transformations, solid-phase oxygen exchange activity, and adsorption characteristics of the oxides. 

Praseodymium is one of the possible "new" additives, which today attracts more and more attention. In fact, it was demonstrated that the oxygen exchange occurs at lower temperature on cerium-praseodymium mixed oxides than on ceria [7]. Furthermore, high temperature pretreatment does not affect the oxygen exchange capacity (OSC) of the mixed oxides. Moreover, high surface area PrOy-Zr02 materials with a fluorite-type structure were also prepared by the sol-gel way [7, 8]. 

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