Pressure Strategy\nTo Improve H Atomic Utilization\nvia Optimized Decomposition Pathway in Solid Hydrazine Borane

Hydrazine borane (N<sub>2</sub>H<sub>4</sub>BH<sub>3</sub>, HB),\na typical B–N–H compound with very high hydrogen content\n(15.4 wt %), is regarded as an efficient hydrogen storage material.\nHowever, during the pyrolysis at ambient pressure, solid HB decomposes,\nlosing ∼30 wt %, which is rationalized by the evolution\nof hydrazine (N<sub>2</sub>H<sub>4</sub>). Here, high pressure is\nintroduced as an analogous catalyst role that enable to optimize the\ndecomposition pathway of solid HB. This approach improves the H atomic\nutilization to over 95%. Energy-dispersive spectroscopy (EDS) analysis\nindicates that pressure inhibits the production of N<sub>2</sub>H<sub>4</sub>, in-situ high-pressure–high-temperature Raman and\nin-situ high-pressure Infrared (IR) spectra, Density functional theory\n(DFT) calculation, and Hirshfeld analysis reveal that this inhibition\nis a consequence of pressure-enhanced dihydrogen and BN bonds. The\nsuperior hydrogen release properties of HB under high pressure make\nit a candidate for use in the synthesis of superconductor CeH<sub>9</sub> as a hydrogen source.