Dependence of H-storage performance on preparation conditions in TiF3 doped NaAlH4

A systematic investigation was performed on the hydrogen-storage performance of TiF3 doped NaAlH4 that was prepared under varied conditions. It was found that the starting material, milling atmosphere (inert or reactive) and milling time all exerted substantial influence on the hydrogen-storage performance of the materials. In particular, the variation of milling time or milling atmosphere was observed to influence only the NaAlH4/Na3AlH6 + Al step, but not the following decomposition/reconstruction of Na3AlH6. Moreover, it was observed that the specific hydrogen-storage performance of the doped hydrides arising from the variation of the preparation conditions persisted through the following dehydriding/rehydriding cycles. These results elucidate the optimized preparation conditions of the NaAlH4–TiF3 system. More significantly, they provide valuable hint in exploring the nature of active Ti-species in the doped NaAlH4.