Atomistic processes of boron and nitrogen near the Pt(111) surface

Two-dimensional h-BN is grown by CVD using precursor molecules containing B and N, which then chemically decompose into constituent atoms on catalytic substrates. Using first-principles calculations, we study adsorption, diffusion, and penetration of B and N atoms separated from the precursors on the Pt(111) surface. These are the essential steps to understand the h-BN growth mechanism on the catalytic substrate. Both B and N atoms are stably adsorbed at the fcc and hcp hollow sites, to form both covalent and ionic bonds with Pt. The B atom becomes more stable in the subsurface, while does not the N atom. The penetration barrier of B is only 0.36 eV. The diffusion barriers of the B atom is 0.49 and 0.61 eV on the surface and in the subsurface, respectively. Whereas a single B-N dimer, which can act as seed for h-BN islands, is not found stable on Pt(111), the linear chains of the B-N dimers become more stable with more B and N atoms. For three B-N dimers, the circular shape less stable than the corresponding linear chain, but the energetics reverses for hydrogenated ones. Based on our results, we discuss the h-BN growth and argue that understanding of the precursor molecules is required further.