Pure hydrogen-generating “doped” sodium hydrazinidoborane

• Sodium hydride-“doped” sodium hydrazinidoborane NaN2H3BH3 was prepared.
• This was done by mixing N2H4BH3 and NaH (5% in excess) in cold conditions.
• Unlike neat NaN2H3BH3, the “doped” counterpart releases pure H2 under heating.
• In dynamic conditions, 8.79 wt% of pure H2 can be liberated at 50–160 °C.
• At 100 °C (isothermal), “doped” NaN2H3BH3 releases 6.9 wt% H2 within <5 min.

In this work, we present the performance of “doped” sodium hydrazinidoborane NaN2H3BH3 as hydrogen carrier. It was prepared by ball-milling hydrazine borane N2H4BH3 and sodium hydride NaH in cold conditions, with an excess of 5 wt% of NaH. Such an excess is essential for the generation of pure hydrogen, i.e. free from the undesired by-products NH3 and N2H4 under heating, whereas for a material prepared in equimolar conditions non negligible amounts of ammonia NH3 are detected. Our main results, i.e. characterization of “doped” sodium hydrazinidoborane, dehydrogenation experiments, analysis of the purity of H2, and characterization of the solid residue, are presented and discussed herein. The potential of “doped” sodium hydrazinidoborane as solid-state chemical hydrogen storage material is finally discussed.