h-BN in the making: The surface chemistry of borazine on Rh(111).

This article focuses on the molecular-level investigation of the adsorption and thermal reaction pathway of borazine (B3H6N3) on the Rh(111) surface to understand the chemical vapor deposition (CVD) growth of hexagonal boron nitride (h-BN). Using synchrotron radiation-based high-resolution x-ray photoelectron spectroscopy (XPS), temperature-programmed XPS, and near-edge x-ray absorption fine structure (NEXAFS), the study reveals that borazine adsorbs mainly intact in a flat-lying geometry at low temperature (130 K), with multilayers desorbing below 200 K. Upon heating, borazine undergoes dehydrogenation and fragment formation, leading to disordered boron nitride above 500 K and the onset of ordered h-BN moiré formation at about 650 K, completing near 1100 K. The resulting h-BN layer exhibits spectral features consistent with previously established "as-prepared" h-BN/Rh(111), confirming successful conversion and providing detailed insight into the surface chemistry and growth mechanism of h-BN on Rh(111).