Improved dehydrogenation properties of the combined Mg(BH_4)_2 · 6NH_3-nNH_3BH_3 system

摘要

A combined strategy via mixing Mg(BH_4)_2·6NH_3 with ammonia borane (AB) is employed to improve the dehydrogenation properties of Mg(BH_4)_2 · 6NH_3. The combined system shows a mutual dehydrogenation improvement in terms of dehydrogenation temperature and hydrogen purity compared to the individual components. A further improved hydrogen liberation from the Mg(BH_4)_2-6NH_3-6AB is achieved with the assistance of ZnCl_2, which plays a crucial role in stabilizing the NH_3 groups and promoting the recombination of NH~(δ-1) … HB~δ . Specifically, the Mg(BH_4)_2·6NH_3-6AB/ZnCl_2 (with a mole ratio of 1:0.5) composite is shown to release over 7 wt.% high-pure hydrogen (>99 mol%) at 95 ℃ within 10 min, thereby making the combined system a promising candidate for solid hydrogen storage.