Hydrogen generation from sodium borohydride solutions using different catalysts for the survival of living beings in the long-time space flights

Hydrogen (H2), environmentally friendly effective energy carrier with the most advantageous combustion by-products, readily attained from borohydride (NaBH4) with higher hydrogen (H2) generation rates (HGRs) as safer than e other hydrates necessitating the use of various catalysts. The catalysts' performances are major factors in high HGR from NaBH4 regardless of hydrolysis or methanolysis reactions. The HGR is influenced by NaBH4 concentrations, reaction temperature, and the catalyst amounts. Nobel metals e.g., ruthenium (Ru), platinum (Pt), Rhodium (Rh) etc reported as highly effective catalysts for fast H2 production from NaBH4 solutions including ethanol, methanol, and ethylene glycol. Due to shortage and cost considerations of noble metals, transition metal-based catalysts e.g., cobalt (Co), nickel (Ni), and manganese (Mn) have gained great interest for H2 production from NaBH4 hydrolysis/alcoholysis. Metal nanoparticle-based catalysts, and their synthetic and natural polymer composites along with non-metallic catalyst including micro/nanogels, bulk hydrogels, cryogels, and polymeric ionic liquids (PILs) have been employed as catalysts in methanolysis/hydrolysis of NaBH4 to attain lower Ea and high HGR values. Therefore, in this review catalysts whether metal or non-metal used in H2 generation reactions will be surveyed, Moreover, space application of H2 energy systems with their commercial application for future use will be assessed.