Ultrasound induced hydrogen release from ammonia borane mediated by oxidized multiwalled carbon nanotube under hydrolytic conditions

• Oxidized multiwalled carbon nanotubes act as efficient, metal-free catalysts for ammonia borane hydrolysis. • Ultrasound irradiation drastically enhances hydrogen release by improving mass transport and catalyst dispersion. • Surface functionalization introducd carboxylic groups that reduce the activation energy by over 77%. • Near-complete hydrogen conversion (98%) is achieved under mild, aqueous conditions • The catalytic system demonstrates reusability and an on–off hydrogen release switchability via ultrasound control. The field of hydrogen storage is one of the last frontiers in the exploitation of hydrogen-based technology. Particularly, the utilization of ammonia borane is a very promising route to solve the issue related to hydrogen storage due to the content of hydrogen up to 19.8 wt% and the stability in the ambient temperature and pressure conditions. Nevertheless, the hydrogen release from ammonia borane is quite complex under thermal stimuli, with several secondary compounds released. Alternatively, hydrolysis of ammonia borane is a simpler route to release of hydrogen in presence of water without any side reaction when a catalyst is used. This study investigates the ultrasound-assisted hydrolytic dehydrogenation of ammonia borane mediated by oxidized multiwalled carbon nanotubes (MWCNTs) as a metal-free energy-efficient catalytic system. The application of ultrasonic irradiation significantly enhanced the catalytic performance by promoting mass transport, improving water molecule activation, and increasing the dispersion and reactivity of the oxidized MWCNTs in the water medium. The oxidized MWCNTs promote the activation of ammonia borane, reducing the activation energy of the systems over 77% and reaching a remarkable hydrogen release efficiency with a conversion of up to 98%.