A reversible hydrogen storage mechanism for sodium alanate: the role of alanes and the catalytic effect of the dopant

We propose a reversible mechanism for sodium alanate. The individual mechanistic reaction steps for the decomposition reaction derive a set of time dependent differential equations that simultaneously produce the evolution plots for each species. These plots reproduce several aspects of in-situ XRD data, as well as the measured relative composition of selected decomposition samples at various extents of reaction. The presence of alanes facilitates both the decomposition and reformation of sodium alanate based on the principle of microscopic reversibility. A major role for the titanium dopant in catalyzed sodium alanate dynamics appears to be alloy formation at the surface of bulk aluminum that facilitates the formation and sorption properties of alanes.