Computational study of boron nitride nanotube synthesis: How catalyst morphology stabilizes the boron nitride bond

In an attempt to understand why catalytic methods for the growth of boron nitride nanotubes work much worse than for their carbon counterparts, we use first-principles calculations to study the energetics of elemental reactions forming N-2, B-2, and BN molecules on an iron catalyst. We observe that the local morphology of a step edge present in our nanoparticle model stabilizes the boron nitride molecule with respect to B-2 due to the ability of the step edge to offer sites with different coordination simultaneously for nitrogen and boron. Our results emphasize the importance of atomic steps for a high yield chemical vapor deposition growth of BN nanotubes and may outline new directions for improving the efficiency of the method.