Hydrogen release from sodium borohydrides at low temperature by the addition of zinc fluoride

The major challenge of complex hydride for hydrogen storage is to release hydrogen at a moderate temperature with rapid kinetics. This paper reports a new composite system (NaBH4/ZnF2) to generate hydrogen at a low temperature below 100 °C. The NaBH4 and ZnF2 mixture was prepared by a mechanical milling in a 2:1 M ratio. Dehydrogenation of the mixture during a heating process shows that the initial dehydrogenation temperature was below 100 °C with favorable kinetics. The structural analysis confirmed the formation of NaBF4 and Zn in the reaction products. The study concerning the reaction mechanism reveals that ZnF2 plays a role of reagent rather than catalyst. The produced intermediate of NaZnF3, however, affects the decomposition of the emitted B2H6. This work suggests that the extension of the decomposition mechanism of NaBH4/ZnF2 composite system would favor the development of new catalysts for complex hydride systems.

► NaBH4-ZnF2 mixture was used as hydrogen storage materials. ► They release hydrogen at a low temperature of below 100 °C with favorable kinetics. ► The produced intermediate of NaZnF3 affects the decomposition of the generated B2H6. ► ZnF2 plays a role of reagent rather than catalyst.