Effect of vanadium catalysts on hydrogen evolution from NaBH4

TL;DR

This study investigates how vanadium-based catalysts lower the temperature needed for hydrogen release from NaBH4, making it more practical for hydrogen storage applications.

Contribution

It demonstrates that mechanochemical doping with vanadium compounds significantly reduces NaBH4's pyrolysis temperature, enhancing its potential as a hydrogen storage material.

Findings

Vanadium catalysts lower NaBH4 decomposition temperature by about 150°C.

NaBH4 with V2O5 or VO2 releases 70% of hydrogen between 370°C and 450°C.

Preparation methods affect hydrogen purity, with certain nanoparticle suspensions causing impurities.

Abstract

NaBH4 is a very cheap and hydrogen rich material and a potential hydrogen store. However, high temperature of its thermal decomposition (above 530{\deg}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{\deg}C to 450{\deg}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.