Ammonia-free infiltration of NaBH4 into highly-ordered mesoporous silica and carbon matrices for hydrogen storage

In this work we focused on nanoconfiment of NaBH4 into highly-ordered Si-based and its carbon replica mesoporous scaffolds by ammonia-free wet chemical impregnation. Structural and morphological characterization, performed by X-ray diffraction and Transmission electron microscopy allowed to confirm the effectiveness infiltration procedure. Desorption properties tested by Temperature programmed desorption analyses highlighted a noticeable shift towards lower temperature than corresponding bulk material and literature data referred to similar systems.JRC.F.2-Cleaner energ

Hydrogen Storage in 2NaBH4 + MgH2 Mixtures: Destabilization by additives and nanoconfinement

We focus on the H2 desorption properties of the 2NaBH4 + MgH2 system destabilized by different methods. Nanostructured powder mixtures were prepared by ball milling the starting hydrides and nanoconfined reactive composites were obtained by melting infiltration of the hydrides into a Si-based SBA-15 support. NbF5 was tested as catalyst in both the preparations. Structural characterization by X Ray Diffraction and Transmission Electron Microscopy allowed evaluating the successful synthesis of SBA15 matrix, the microstructural features of ball milled and nanoconfined hydrides as well as the success of infiltration process. The evaluation of the sorption properties, by manometric Sievert-type apparatus and thermal desorption spectroscopy, revealed the efficiency of the hydride destabilization, obtained by the different routes, in decreasing the hydrogen release temperature and improving desorption kinetics.JRC.F.2-Cleaner energ

St\ue4rka den kvinnliga forskarens roll inom nanoforskningen

Rapport "WomenInNano" ProjektEn specifik st\uf6dfunktion initierad av Europeiska kommissionen i det 6:e ramprogrammet f\uf6r forskning, etenskap och samh\ue4lle, kvinnor och vetenskap. Oktober 2005 - Mars 2008

Pressure Effect on the 2NaH+MgB2 Hydrogen Absorption Reaction

The hydrogen absorption mechanism of the 2NaH + MgB2 system has been investigated in detail. Depending on the applied hydrogen pressure, different intermediate phases are observed. In the case of absorption measurements performed under 50 bar of hydrogen pressure, NaBH4 is found not to be formed directly. Instead, first an unknown phase is formed, followed upon further heating by the formation of NaMgH3 and a NaH-NaBH4 molten salt mixture; only at the end after heating to 380 degrees C do the reflections of the crystalline NaBH4 appear. In contrast, measurements performed at lower hydrogen pressure (5 bar of H-2), but under the same temperature conditions, demonstrate that the synthesis of NaBH4 is possible without occurrence of the unknown phase and of NaMgH3. This indicates that the reaction path can be tuned by the applied hydrogen pressure. The formation of a NaH-NaBH4 molten salt mixture is observed also for the measurement performed under 5 bar of hydrogen pressure with the formation of free Mg. However, under this pressure condition the formation of crystalline NaBH4 is observed only during cooling at 367 degrees C. For none of the applied experimental conditions has it been possible to achieve the theoretical gravimetric hydrogen capacity of 7.8 wt %