Effect of Vanadium Catalysts on Hydrogen Evolution from NaBH4

Abstract

NaBH4 is a very cheap and hydrogen-rich material, as well as a potential hydrogen store. However, the high temperature of its thermal decomposition (above 530 °C) renders it inapplicable in practical use. Here, we studied the effect of addition of diverse V-containing catalysts on thermal hydrogen desorption. It turns out that mechanochemical doping of NaBH4 with vanadium metal, its oxides, or nanoparticles lowers the temperature of pyrolysis significantly. Notably, NaBH4 milled for 3 h with 25 wt.% V2O5 or VO2 releases ca. 70% of stored hydrogen in the temperature range of ca. 370–450 °C. On the other hand, precursors and solvents used to prepare rather uniform vanadium nanoparticles (~4 nm) suspended in THF or less uniform and larger ones (~15 nm) in o- difluorobenzene have adverse effect on the purity of hydrogen evolved.