Description :  

The principal objective of this research program is to determine the distances between dopant atoms and host atoms using synchrotron x-ray absorption spectroscopy in order to engineer predicted hydrogen desorption kinetics.  An interdisciplinary team has been assembled to approach this problem using advanced characterization, atomic layer-by-layer nanosynthesis, density functional theory simulations, and industrial engineering materials performance testing.

Complex metal hydrides have been studied for decades as unique materials capable of incorporating hydrogen into their lattice.  A recent surge in research of these materials can be attributed to need for safe and economic storage means for hydrogen fuel.  Recent research has shown that dopant additions to complex metal hydrides can enhance hydrogen desorption kinetics.  The atomic-scale location of these dopants has not been fully described.  As well, a mechanism for the kinetic enhancements associated with these dopants has not been fully developed.  This project proposes to study the local bonding environment of the dopant atoms using extended x-ray absorption fine structure (EXAFS) and x-ray absorption near edge structure (XANES).  Using these techniques, information will be provided about the local bond length between dopant and host atoms and coordination number for dopant atoms.  This information is much needed by the hydrogen storage research community—since a trial-and-error approach to dopant selection and stoichiometry is currently taken.  This project will expound upon this work to provide an understanding of the role of dopant valence state and site location within host lattice.  Coupled with existing information regarding the kinetics of hydrogen desorption, knowledge of the atomic-scale interactions between the dopant atoms and host lattice will provide a broader understanding of mechanisms for improved desorption rates.

---

Principal Investigator:  Dobbins, Tabbetha  --  Physics

---

Collaborators:  Daniela Mainardi, Yuri Lvov

---

Funding Agencies:  Department of Energy--Office of Science

---

Amount Awarded:  $300,000.00

---

Start Period:  09/01/2005

End Period:  08/31/2008