Boron Nanoparticles for Room-Temperature Hydrogen Generation from Water

Boron nanoparticles (BNPs) are of great interest for applications such as neutron capture therapy of cancer cells, hydrogen generation from water, and high energy density fuels. Boron is particularly interesting for chemical water splitting, because of its high gravimetric hydrogen generation potential of 277 g H₂ per kg B. However, only a few studies of water splitting by reaction with boron are available, and those have used high temperature steam with external heating. Room-temperature boron hydrolysis is of great interest from both scientific and practical perspectives. The studies presented here demonstrate that high purity amorphous BNPs can be oxidized by water to produce H₂ at room temperature, without external energy input, in the presence of catalytic quantities of an alkali metal or alkali metal hydride. The BNPs are produced in a single step gas phase process via CO₂ laser-induced pyrolysis of mixtures of B₂H₆ and SF₆. The BNPs are spherical with a primary particle diameter of 10–15 nm, narrow size distribution, and specific surface area exceeding 250 m² g⁻¹. This first demonstration of room-temperature chemical splitting of liquid water using boron opens up exciting new possibilities for on-demand hydrogen generation at high gravimetric capacity.