Published December 25, 2015 | Version Final version
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Cyclic stability and structure of nanoconfined Ti-doped NaAlH4

Creators

  • 1. Interdisciplinary Nanoscience Center (iNANO) and Department of Chemistry, Aarhus University, Langelandsgade 140, DK-8000 Arhus C, Denmark
  • 2. Institute of Materials Research, Materials Technology, Helmholtz-Zentrum Geesthacht GmbH, Max-Planck-Strasse 1, D-21502 Geesthacht, Schleswig-Holstein, Germany
  • 3. Institute of Materials Research, Helmholtz-Zentrum Geesthacht, 21502 Geesthacht, Germany and Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) and Centro Atómico Bariloche, Av. Bustillo 9500, R8402AGP S. C. de Bariloche, Río Negro, Argentina
  • 4. Institute of Materials Research, Helmholtz-Zentrum Geesthacht, 21502 Geesthacht, Germany
  • 5. Helmholtz-Zentrum Berlin fu¨ r Materialien und Energie, Hahn-Meitner Platz 1, D-14109 Berlin, Germany
  • 6. HASYLAB at DESY, Notkestraße 85, D-22603 Hamburg, Germany

Description

NaAlH4 was melt infiltrated within a CO2 activated carbon aerogel, which had been preloaded with TiCl3. Nanoconfinement was verified by Small Angle X-Ray Scattering (SAXS) and the nature of the Ti was investigated with Anomalous SAXS (ASAXS) and X-Ray Absorption Near Edge Structure (XANES) to determine its size and chemical state. The Ti is found to be in a similar state to that found in the bulk Ti-doped NaAlH4 system where it exists as Al1-xTix nanoalloys. Crystalline phases exist within the carbon aerogel pores, which are analysed by in-situ Powder X-Ray Diffraction (PXD) during hydrogen cycling. The in-situ data reveals that the hydrogen release from NaAlH4 and its hydrogen uptake occurs through the Na3AlH6 intermediate when confined at this size scale. The hydrogen capacity from the nanoconfined NaAlH4 is found to initially be much higher in this CO2 activated aerogel compared with previous studies into unactivated aerogels.

Notes

Beamline I711, MAXII laboratories, Lund, Sweden are thanked for the allocated beam time. Parts of this research were performed at the light source DORIS III at DESY, a member of the Helmholtz Association (HGF). The authors would like also to thankCONICET (Consejo Nacional de Invetigaciones Científicas y Tecnicas), and DAAD (German Academic Exchange Service) e Ministerio de Educación de la Nación Argentina (Sandwich Grant Program) (Grant Number e A/09/75212) for financial support to carry out this work. The authors acknowledge financial support from The Danish Council for Strategic Research via the research project HyFillFast and The Danish Council for Independent Research for DFF Mobility 1325-00072.

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