Enhanced dehydrogenation of hydrazine bisborane for hydrogen storage

•NiCl2 enhanced dehydrogenation of hydrazine bisborane (HBB) was reported.•By adding NiCl2, the desorption rate and the hydrogen purity were improved.•A possible explanation was proposed to understand NiCl2 enhanced desorption of HBB.

NiCl2 and CoCl2 were adopted to enhance the dehydrogenation of hydrazine bisborane (HBB), respectively, of which NiCl2 showed better performance. By adding 2.0 mol. % NiCl2, the dehydrogenation property of HBB was significantly improved, for example, the impurity of NH3 during the dehydrogenation of HBB was totally suppressed with more than 13.0 wt. % of pure hydrogen evolved. By Kissinger method, the apparent activation energies of the first step for HBB and Ni-doped HBB were calculated to be 143.2 and 60.7 kJ mol−1, respectively. DSC result showed that the addition of NiCl2 did not change the enthalpy change of HBB dehydrogenation. Based on theoretical analysis and literature review, the improved dehydrogenation property of HBB was potentially ascribed to the solid state interaction of Ni2+ with the electronegative N in the NH2 group of HBB.