| Title: | DEHYDROGENATION MECHANISM FROM TITANIUM-ACTIVATED SODIUM ALANATE |
| DOI No: | 10.1142/9789812838025_0009 |
| Source: | MATERIALS ISSUES IN A HYDROGEN ECONOMY (pp 102-115)
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| Author(s): | SA LI
Department of Physics, Virginia Commonwealth University, Richmond, VA 23284, USA
P. JENA
Department of Physics, Virginia Commonwealth University, Richmond, VA 23284, USA
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| Abstract: | Addition of a small amount of Ti precursors to sodium alanate has recently been found to substantially improve the kinetics and thermodynamics of hydrogen sorption. In spite of several attempts, a fundamental understanding of how the catalyst works has remained unattainable. Using first principles calculations we have investigated the mechanisms for hydrogen desorption in this material by substituting Ti at various sites as well as creating a variety of vacancies. The lowest energy cost is when Ti replaces an AlH pair. Following this replacement, Ti attracts neighboring H atoms. Hydrogen desorption from this Ti neighborhood is much more efficient than from AlH4 complex in pristine NaAlH4. The formation of the AlH3 vacancy, even though it is the easiest among all vacancy formation, yields higher creation energy than when Ti replaces the AlH pair. These results provide important new insight into the design of future catalysts for hydrogen storage materials. |
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