Solid-Phase Hydrogen Storage Based on NH3BH3-SiO2 Nanocomposite for Thermolysis.

Current H₂-proton exchange membrane fuel cell systems available for commercial applications employ heavy and high-risk physical hydrogen storage containers. However, these compressed or liquefied H₂-containing cylinders are only suitable for ground-based electric vehicles, because although highly purified H₂ can be stored in a cylinder, it is not compatible with unmanned aerial vehicles (UAVs), which require a lighter and more stable energy source. Here, we introduce a chemical hydrogen storage composite, composed of ammonia borane (AB) as a hydrogen source and various heterogeneous catalysts, to elevate the thermal dehydrogenation rate. Nanoscale SiO₂ catalysts with a cotton structure dramatically increase the hydrogen evolution rate on demand, while simultaneously lowering the startup temperature for AB thermolysis. Results show that the dehydrogenation reaction of AB with a cotton-structured SiO₂ nanocatalyst composite occurs below 90°C, the reaction time is less than a minute, and the hydrogen generation yield is over 12 wt%, with an activation energy of 63.9 kJ·mol^-1. [ABSTRACT FROM AUTHOR]