Chengguo Yan,Jiaguang Zheng,Ao Xia,Qingbo Zhang,Meiling Lv,Zhenxuan Ma,Chao Su,Zhendong Yao
Among conventional hydrogen storage materials , LiBH 4 has been regarded as one of the best hydrogen transporters due to its relatively large hydrogen capacities. However, because of its extraordinarily high dehydrogenation temperatures, LiBH 4 was not suitable for hydrogen storage due to its stable thermodynamic features. Herein, we present a novel approach to LiBH 4 that uses solid-state multi-hydroxyl mannitol as a reactant, regulating hydrogen release below 69.9 °C. More than 7 wt% H 2 could be released with ultra-fast rates at 140 °C from the LiBH 4 -mannitol composite. XRD , FTIR , and SEM tests revealed that the reaction between mannitol (H δ+ ) and LiBH 4 (H δ− ) to produce hydrogen was accompanied by the generation of large amounts of heat in situ, which further promoted the decomposition of LiBH 4 for hydrogen production , exceeding the theoretical dehydrogenation amount of H δ+ - H δ− reaction. This work indicates possibilities for the development of fast and easy high-capacity hydrogen generation systems based on complex hydrides.
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 (NaBH 4 /ZnF 2 ) to generate hydrogen at a low temperature below 100 °C. The NaBH 4 and ZnF 2 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 NaBF 4 and Zn in the reaction products. The study concerning the reaction mechanism reveals that ZnF 2 plays a role of reagent rather than catalyst. The produced intermediate of NaZnF 3 , however, affects the decomposition of the emitted B 2 H 6 . This work suggests that the extension of the decomposition mechanism of NaBH 4 /ZnF 2 composite system would favor the development of new catalysts for complex hydride systems.
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