Silica hollow nanospheres as new nanoscaffold materials to enhance hydrogen releasing from ammoniaborane

Abstract

Silica hollow nanospheres (SHNS) are used as new nanoscaffold materials to confine ammonia borane (NH₃BH₃, AB) for enhancing the dehydrogenation process. Different loading levels of AB in SHNS are considered and AB/4SHNS (with AB content of approximately 20 wt%) shows the best result. The onset temperature of the dehydrogenation of AB in SHNS is as low as 70 °C with the peak temperature at 99 °C and no other gases such as borazine and ammonia are detected. Furthermore, within 60 min at 85 °C, 0.53 equivalent of hydrogen is released and the activation energy is 97.6 kJ mol⁻¹. Through FT-IR, Raman spectrum and density functional theory (DFT) calculation, it is found that nanoconfinement effect combined with SiO–H⋯H–B interaction is essential for the enhancement of hydrogen releasing.