Nucleation Mechanism of h-BN on the Au(111) Surface

Chemical vapor deposition (CVD) growth of hexagonal boron nitride (h-BN) is considered to be one of the most promising approaches for the controlled mass production of h-BN thin films, which is a prerequisite for practical applications. However, the nucleation and growth mechanisms of h-BN crystals remain unclear. In this study, we examine h-BN growth on a Au(111) substrate to gain insights into the nucleation process of h-BN during CVD. We systematically investigate the structural nucleation behavior of h-BN clusters on Au(111) substrates using density functional theory combined with an unbiased global search method. The results reveal that distinct structural transformations of h-BN clusters occur when the atomic number is 12 or higher. These h-BN clusters tend to form 2D sp(2) network-like structures by combining quadrilateral and hexagonal shapes at the edges, effectively preventing the formation of B-B and N-N bonds. Furthermore, we find that the chemical potential difference (Delta mu) significantly influences h-BN nucleation. In B-rich (BnNn-1) or N-rich (Bn-1Nn) environments, a chain structure initially forms and subsequently transforms into a 2D sp(2) network structure. These findings have significant implications for experimental h-BN growth on metal substrates as they facilitate the production of large-area, defect-free h-BN nanosheets.