Improved dehydrogenation properties of the combined Mg(BH4)2·6NH3–nNH3BH3 system

•Mg(BH4)2·6NH3–nAB showed a mutual dehydrogenation improvement.•Introduction of ZnCl2 further improved dehydrogenation of Mg(BH4)2·6NH3–6AB.•Over 7 wt.% pure H2 was released from the composite at 95 °C within 10 min.

A combined strategy via mixing Mg(BH4)2·6NH3 with ammonia borane (AB) is employed to improve the dehydrogenation properties of Mg(BH4)2·6NH3. 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(BH4)2·6NH3–6AB is achieved with the assistance of ZnCl2, which plays a crucial role in stabilizing the NH3 groups and promoting the recombination of NHδ+⋯HBδ−. Specifically, the Mg(BH4)2·6NH3–6AB/ZnCl2 (with a mole ratio of 1:0.5) composite is shown to release over 7 wt.% high-pure hydrogen (>99 mol%) at 95 °C within 10 min, thereby making the combined system a promising candidate for solid hydrogen storage.

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