Ammonia borane confined by poly(methyl methacrylate)/multiwall carbon nanotube nanofiber composite, as a polymeric hydrogen storage material

Abstract

In this work, poly(methyl methacrylate)/ammonia borane/multiwall carbon nanotube (PMMA/AB/MWCNT) nanofiber composites have been fabricated and the synergetic nanoconfinement effect of nanofiber and CNT components on dehydrogenation temperature and liberating unwanted byproducts of AB (NH₃BH₃) have been studied. The results of dehydrogenation of PMMA/AB and PMMA/AB/MWCNT samples show 112 and 85 °C exothermic reaction temperatures, which are dramatically lower than pure AB (120 °C). Furthermore, by capture and interaction of AB molecules in the MWCNT and PMMA nanofiber structures, the enthalpy of exothermic decomposition decreases from −21.00 to −1.83 kJ mol⁻¹ H₂, suggesting that this type of AB nanofiber composite can provide a convenient reversible hydrogen storage material. The utilization of MWCNT as carbon catalyst and confining of AB result in a decrease of ammonia borane weight loss from 60.00 to 2.88 wt% which in turn can vigorously decline the emission of byproduct impurities. The synthesis process of PMMA/AB/MWCNT nanofiber composites causes the crystal structure of AB particles changed to the amorphous structure which has been clearly confirmed by X-ray diffraction analyses. The strategy of combining nanofiber structure and MWCNT as carbon catalyst with AB particles can be presented as a practicable solution to reach lower operational temperature and to decline undesirable volatile products.