Metal B-N-H hydrogen-storage compound: Development and perspectives

Metal boron-nitrogen-hydrogen (MBNH) compound is a kind of typical solid hydrogen storage material characterized by hydrogen-rich B-N species, which has been developed very fast in the last decade due to its high hydrogen capacity and the tunable hydrogen storage properties, such as metal amidoborane (M(NH2BH3)(n), MAB), metal hydrazinidoborane (M(NH2NH2BH3)(n), MHB), amine metal borohydride (M(BH4)(n)center dot mNH(3), AMB) and their derivatives. MAB is obtained by replacing a hydrogen cation of AB (NH3BH3) by a light metal cation (such as the alkali or alkali earth metal, generally), which was a famous hydrogen-storage material in last 15 years. MHB is formed by replacing a H(N) atom with light metal, which is similar with that of MAB. AMB is synthesized by the reaction between metal borohydrides and ammonia. There are a large amount of AMBs prepared in the recent ten years with different metals or different coordination numbers of NH3. In this field, all the compounds are containing a strong Lewis acid/base interaction (such as B-N interaction). Hydrogen is generated from the dihydrogen bond of H delta+ center dot center dot center dot H delta-, where the metal works as a controllable hydrogen carrier to improve the purity of product in the dehydrogenation process. In this review, we focus on the novel solid MBNH compounds including MAB, MHB and AMB with their synthesis methods, structures and dehydrogenation properties. We hope this review can enlighten more extensive studies for the development of new MBNH compounds with advanced hydrogen storage performances. (c) 2019 Elsevier B.V. All rights reserved.