A solid-state system for controllable hydrogen release: ammonia borane encapsulated in a catalyst-loaded graphene...

Achieving precise "on-off" control over hydrogen release is crucial for the efficient on-demand utilization of hydrogen energy. This study proposes a novel solid-state storage strategy, which involves loading ammonia borane (AB) and a cobalt catalyst into a graphene aerogel (AB@Co/RGOA), to regulate hydrogen generation via water-mediated hydrolysis. Characterization reveals that Co nanoparticles are uniformly dispersed on the graphene aerogel, while AB is effectively encapsulated within the structure to form a bulk solid composite. This AB@Co/RGOA system enables switchable hydrogen production, which can be precisely initiated and halted by modulating the water supply to the aerogel. Furthermore, the Co-decorated RGO framework (Co/RGOA) remains intact after AB is fully consumed and can be reloaded with fresh AB for subsequent cycles. The catalyst exhibits favorable catalytic activity toward AB hydrolysis with a turnover frequency (TOF) of 109.63 min^-1 at 25 °C. Moreover, the catalyst retains over 90% of its initial activity after five cycles of reuse. This work not only presents a viable approach to managing hydrogen release for potential on-board applications but also establishes a generalizable strategy that can be adapted to other catalyst-loaded porous materials for controlled hydrolytic hydrogen generation.