Pressure-Induced Phase Transition of Hydrogen Storage Material Hydrazine Bisborane: Evolution of Dihydrogen Bonds

Abstract

We report the high-pressure behavior of dihydrogen-bonded hydrogen storage material hydrazine bisborane (BH₃N₂H₄BH₃, HBB) via in situ angle-dispersive X-ray diffraction (ADXRD) and Raman spectroscopy in a diamond anvil cell up to 2.0 GPa. A reversible phase transition at 0.4 GPa was confirmed by ADXRD experiments. The Rietveld refinement showed the high-pressure phase was consistent with the crystal structure of α′-phase (low-temperature phase). Through the analysis of structure changes, Raman spectroscopy, and the Hirshfeld surface, we studied the evolution of dihydrogen bonds under high pressure and attributed the pressure-induced phase transition to the distortion and rotation of the NH₂–NH₂ group. This work will further the understanding of the characteristics of dihydrogen bonds and provide some contribution to future hydrogen storage applications of HBB