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

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 degrees C with the peak temperature at 99 degrees C and no other gases such as borazine and ammonia are detected. Furthermore, within 60 min at 85 degrees 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 center dot center dot center dot H-B interaction is essential for the enhancement of hydrogen releasing.