Boron nanocrystals as high-energy-density fuels

Boron's potential as a fuel or fuel additives has not been fully realized to date, largely due to the difficulty in igniting and burning it efficiently. To confront this challenge freestanding boron nanocrystals (B NCs) with tunable sizes have been synthesized by a cost-effective gas phase nonthermal plasma approach. The crystal phase of B NCs is identified to be beta-rhombohedral (space group R (3) over barm) by using transmission electron microscopy and Raman spectroscopy measurements. Thermogravimetric analysis and differential scanning calorimetry study indicates the ignition temperature of B NCs in air monotonically decreases from 529 to 524 and 506 degrees C as the NC size changes from 14.9 to 10.4, and 4.7 nm, and the amount of heat release correspondingly increases from 16.1 to 21.1 and 22.8 kJ g(-1). The size-dependent energy releases of B NCs are elucidated by using x-ray photoelectron spectroscopy.