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Oxides

Oxides

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Reversible CO2 Capture by lithium or sodium oxides

The capture and recycling of atmospheric CO2 is a major goal in the fight for a cleaner world. The use of oxides containing alkali metals is one the technologies described in the literature for CO2 trap.

Then, in the search for new materials able to capture CO2, we focused on compounds with high alkali metal content and having an open structure to promote the alkali diffusion. These characteristics are indispensable prerequisites to allow an expected exchange alkali+/H+ followed by the reversible CO2 capture through the formation of a carbonate on the whole surface of the grains. We also focus on the  chemisorption performance as sorption/desorption temperatures, CO2 holding capacity (g CO2/g sorbent) and cyclability.

Finally, the structural characterization of the exchanged oxide is performed with several complementary techniques.

 

Researchers

  • Cyrille Galven
  • Françoise Le Berre
  • Marie-Pierre Crosnier-Lopez

Related papers

  • Inorg. Chem. 2016, 55, 12872
  • Inorg. Chem. 2018, 57, 7334

Oxides with ionic mobility

This research axis deals with the study of oxide materials presenting ionic conductivity properties, either anionic or cationic. Note that in most oxides, the largest ions are anions (O2-), whereas cations are smaller, sometimes much smaller. Anionic migration is therefore more difficult, and requires higher temperatures than cation migration, especially when cations are lighter.

Our initial works, which concerned compounds related to oxide- ion conductor La2Mo2O9 (LAMOX) and to lithium-ion conductor (La,Li)TiO3 (LLTO), were extended to other materials.

For oxide-ion conductors, we took an interest in all SOFC core cell components aside LAMOX electrolyte, namely in mixed ionic-electronic conductors derived from LAMOX reduction, as anode materials, and in cationic cross-diffusion at the electrolyte/cathode interface. [On the last period, we studied the influence of nanostructure on the ionic conductivity of La2Mo2O9, its reduction kinetics and the local order in the reduced amorphous mixed conductor La2Mo2O6.7 (EXAFS), and cationic cross-migration at the interface between La2Mo2O9 and cathode material (La,Sr)MnO3-d (SIMS)].

Concerning cation conductors, other structural types were studied (Ruddlesden-Popper, NASICON,...), as well as other mobile ions for batteries (H+, Na+,...).[For instance, in the NASICON structural type, the local order and cationic dynamics were studied (solid state NMR) in lithium compounds, as well as conductivity and relaxation times in sodium compounds (complex impedance). With the same technique, proton conductivity of a phosphate glass was studied.]

Researchers

  • Maud Barré
  • Sandrine Coste
  • Gwenaël Corbel
  • Philippe Lacorre

Related papers

  • Inorg. Chem. 2016, 55, 2522
  • Phys. Chem. C 2016, 120, 26173

Photoactive semiconducting oxides

Photoactive semiconducting oxides are promising materials for the preservation of the environment or to develop new sources of energy.

Several structures are investigated in our group and consist in bismuth vanadates, titanium dioxide, nickel titanates or combined heterostructures  associating  metallic doping elements. Different architectures such as nanoparticles, mesoporous structures, nanostructured films are created by using physical or chemical synthesis methods in the aim to enhance the efficiency of the photocatalytic reactions applied in the area of water and atmosphere depollution.

 

  Researchers

  • Abdelhadi Kassiba
  • Sandrine Coste
  • Alain Jouanneaux

Related papers

  • Photoactive semiconducting oxides for Energy and Environment, Handbook of computational chemistry - Springer 2017

Investigate crystal chemistry

This research axis is a crucible, the aim of which is to develop new ideas and materials which will feed other axes, or help create new ones. One of the main tool used is the reasoned exploration of phase diagrams, using whatever rule or hint for the choice of components considered appropriate by the investigator.

This exploration allows the identification of new, hitherto unknown phases, the structure and properties of which will be determined and characterized. The team expertise in ab initio structure determination, for instance through the use of the Le Bail method (from a prominent elder of the lab), is here a benefit . The displayed properties may fit or not with those aimed at, and will be liable, for the most promising ones, to further studies in other -either already existing or to be created- research axes.

Another useful approach is to reexamine the structure of known materials, which might have been insufficiently or incorrectly analyzed in the past, and for which our skills in crystallography allow a more accurate, and therefore more relevant description for a better understanding of their properties.

 

Researchers

  • Marie-Pierre Crosnier-Lopez
  • Françoise Le Berre
  • François Goutenoire
  • Maud Barré
  • Sandrine Coste
  • Amandine Guiet
  • Alain Jouanneaux
  • Gwenaël Corbel
  • Philippe Lacorre

Related papers

  • J. Solid State Chem. 2015, 229, 129
  • Inorg. Chem. 2016, 55, 2309
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