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Effect of vanadium catalysts on hydrogen evolution from NaBH4

NaBH4 is a very cheap and hydrogen rich material and a potential hydrogen store. However, high temperature of its thermal decomposition (above 530°C) renders it inapplicable in practical use. Here, we have 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 hrs with 25 wt.% of V2O5 or VO2 releases ca. 70 % of stored hydrogen in the temperature range from ca. 370°C to 450°C. On the other hand, precursors and solvents used to prepare rather uniform vanadium nanoparticles (ca. 4nm) suspended in THF or less uniform and larger ones (ca. 28nm) in ortho difluorobenzene, have adverse effect on purity of hydrogen evolved.