Nanocomposites for hydrolysis of NaBH4, nanomaterials for hydrogen storage applications

Abstract Depleting nonrenewable energy resources and threat of global warming due to increases in the level of greenhouse gases have been alarming and under worldwide consideration. Both issues garnered scientific attention for developing new strategies for alternative, and sustainable resources of energy that will help sustain correct levels of atmospheric gases. In this context, hydrogen gas (H2), because it bears a high amount of chemical energy, has been scrutinized as a promising nominee for renewable energy. But its property of low-storage density, both by liquefaction and compression, had made it unfit for using in automotive and portable devices. Therefore, manufacturing H2 from hydrolysis of metal hydrides have been found to be exemplary as revealed in literature reported by researchers while finding out the compounds bearing high-storage density of H2. Among metal hydrides, sodium borohydride (NaBH4) is found to have higher levels of H2, theoretically 10.8 of its wt.%, with safe handling. But, this production of H2 via hydrolyzing the alkaline NaBH4 was not simple and spontaneous, but achievable using an appropriate catalyst, as this reaction needs high amount of activation energy. Noble metal catalysts, like nanoparticles of ruthenium (Ru), platinum (Pt), or palladium (Pd) as such or decorated onto carbon nanotubes and silicon carbon nitrides have shown an efficient production of H2, but their usage on commercial scale is avoided due to scarcity and high cost. It is thus the transition metal catalysts like iron (Fe), nickel (Ni), and cobalt (Co) have also been explored in hydrolysis of NaBH4 and found somewhat lesser in performance and good in recyclability when compared with noble metals.