An insight into the dehydrogenation behaviour of LiBH4 exhibiting remarkable kinetics enhanced by nanostructured h-BN

Abstract

In this work, the effect of nanostructured h-BN on the dehydrogenation of LiBH4 is reported. The complex dehydrogenation behaviour of the LiBH4-BN composite is revealed, including the B-H and Li-H splitting processes. Nanostructured h-BN acts as a catalyst not only to effectively promote the dehydrogenation kinetics of LiBH4 but also to facilitate the dehydrogenation of the LiH product. We assume that the enhanced dehydrogenation kinetics originates from the polar mechanism. Namely, the polar mechanism originates from the difference in the Pauling's electronegativity χp values of the elements in h-BN, [BH4]¯ and LiH, which results in the polarizable interactions of B-H⋯B-N and Li-H⋯B-N causing structural destabilization. The results suggest that the microstructure of h-BN plays an important role in enhancing the catalytic effect, and the nanosized effect of LiBH4 assists in improving the dehydrogenation performance. Further experiments and computational modelling that explore the detailed catalytic effect and optimize the microstructure of h-BN will be very useful to facilitate the synthesis of the advanced LiBH4-BN composite.