NSLS 2004 Annual Users’ Meeting Workshop

Applications of Synchrotron-based Methods to Hydrogen Storage Materials

A workshop on Applications of Synchrotron-based Methods to Hydrogen Storage Materials was held in conjunction with the 2004 National Synchrotron Light Source (NSLS) Users’ Meeting on May 19, 2004. The purpose of the workshop was to bring together scientists who synthesize materials with application to hydrogen storage, and scientists with expertise in the application of synchrotron radiation methods, who currently study these materials.

The workshop was opened by Doon Gibbs, the Associate Laboratory Director for Basic Energy Sciences of Brookhaven National Laboratory. He emphasized the importance of the Hydrogen Energy Project (production, storage, utilization) as one of the missions of the Department of Energy (DOE), and encouraged collaborations between scientists within Brookhaven National Laboratory and with outside groups by utilizing facilities like the NSLS and the Center for Functional Nanomaterials (CFN) for research.

John Petrovic from the Hydrogen Storage Team in the DOE Office of Hydrogen, Fuel Cells, and Infrastructure Technology, described in his talk titled “The DOE National Hydrogen Storage Project: Addressing Key Performance Targets for Materials-based Hydrogen Storage Systems” the targets for automotive research over the next 15 years, and the funding efforts by the DOE to reach these targets He presented different projects and Centers of Excellence, that actively work in the field of Hydrogen Storage and which pursue different paths trying to create a successful system.(Wolfgang, that was a very long sentence…can you break it up a bit?) Currently, none of the proposed hydrogen storage systems achieves the proposed targets for 2005!

James Reilly from the Department of Energy Science and Technology at Brookhaven National Laboratory (BNL) described in his talk “The Application of Hydrogen Driven Metallurgical Reactions to Prepare Reactive Nanoscale/Nanocomposite Materials” several ways to create nano-composite metal-hydrides, and their properties. By doping some materials with fairly large amounts of different metals, the storage capacity can be increased, and the temperature for release lowered.

Zafar Iqbal of the Department of Chemistry and Environmental Science of New Jersey Institute of Technology talked about “Electrochemically-Induced Hydrogen Storage in Metal-Functionalized Carbon Nanotubes”. He described different ways to synthesize single-wall nanotubes, ways to functionalize the SWNT with metals, and their properties. Experimental investigation with Raman and FTIR spectroscopy indicate a chemisorption process in Co-doped SWNT, while (weaker) physisorption is present in undoped nanotubes.

Tom Vogt of the Center for Functional Nanomaterials at BNL talked about “Hydrogen Storage and Nano-Structure”. He emphasized the importance to clearly characterize the materials for better understanding of the storage and release mechanisms. High-brightness synchrotron radiation sources like the proposed NSLS-II are ideal sources for real-space and dynamical imaging. Also probes in the CFN like proximal probes are well suited to study single wall nanotubes, for example.

Alexander Ignatov of the Department of Physics of New Jersey Institute of Technology presented in his talk “X-ray Absorption Studies of Hydrogen Storage Materials – Strength and Limitations” experimental results of EXAFS and XANES experiments studying the Ti K-edge in Ti-doped NaAlH₄. The data indicate that Ti does not substitute Na in the lattice. Instead, amorphous TiAl₃ is formed, and H is found in the first coordination sphere about Ti. The EXAFS-analysis allows extraction of the position of H, but the H coordination numbers have large errors.

Yan Gao from GE Global Research Center talked about “Characterization of NaAlH₄ by High-Pressure X-ray Diffraction and in-situ EXAFS”. He presented the first powder-diffraction data of the re-hydrogenation process measured with high time-resolution. The data clearly indicate that two steps in the dehydrogenation and re-hydrogenation have to be completed individually before the next step can start. He also observed an increase in particle-size, which slows down the reactions. His Ti XAS-data also indicate formation of TiAl₃, and the growth of TiAl₃-crystals with the number of cycles.

The final speaker, Najeh Jisrawi from Department of Physics and Astronomy at Rutgers University, discussed “Synchrotron XRD Studies of Hydrogen Absorption in Metallic Multilayers and Nano-Particles”. He applied surface x-ray diffraction to study charge-discharge curves of Pd and Nb/Pd/Nb thin films, and of polyhedral clusters with magic-number sizes. Molecular Dynamics calculations support his experimental results, and demonstrate that a cluster with a size of 8nm shows similar behavior to a thin film.

The workshop was concluded with a brief discussion of techniques and equipment that are required for further successful studies of Hydrogen Storage Materials at the NSLS.

ACKNOWLEDGEMENTS
The National Synchrotron Light Source is supported by the U.S. Department of Energy, Division of Materials Sciences and Division of Chemical Sciences, under Contract No. DE-AC02-98CH10886.

FOR MORE INFORMATION
Wolfgang Caliebe
Building 725D
National Synchrotron Light Source
Brookhaven National Laboratory
Upton, New York 11973-5000
Tel.: (631) 344-4744
Fax: (631) 344-3238
Email: caliebe@bnl.gov

Trevor Tyson
Department of Physics
New Jersey Institute of Technology
161 Warren Street
Newark, New Jersey 07102-1982
Tel.: (973) 642-4681
Fax: (973) 596-5794
Email: tyson@adm.njit.edu