Study of kinetics and thermal decomposition of ammonia borane in presence of silicon nanoparticles

Ammonia borane (AB, NH3BH3) is a promising material by virtue of its high gravimetric hydrogen storage capacity of 19.6 wt%. Hydrogen release from AB initiates at around 100 °C and as such is compatible to meet the present-day requirements of a PEM fuel cell. The thermal decomposition of AB is a complex process involving several reactions. Major issues include poor reaction kinetics, leading to delayed commencement of hydrogen generation i.e. long induction period, and the small amount of hydrogen released at optimal temperature. In the current paper the thermal decomposition of AB is studied at different temperatures. Further the effect of Si nanoparticles on the induction period and kinetics as well as the gas release reaction is studied in detail using different characterization techniques. It was found that the induction period reduced and the amount of gas released increased as a result of Si nanoparticle addition. This was facilitated by a reduction in the activation energy of decomposition and improved kinetics with the addition of silicon nanoparticles.

► Silicon nanoparticles were successfully synthesized by ball milling.
► Ammonia Borane decomposed without induction period in presence of Si nanoparticles.
► Evolved gas in isothermal decomposition was found to be hydrogen only.
► Avrami–Erofeyev model was used for kinetics analysis of thermolysis of AB.
► Presence of Si nanoparticles reduced activation energy from 34.46 to 31.6 kJ/mol.