Surface Chemistry of a Halogenated Borazine: From Supramolecular Assemblies to a Random Covalent BN‐Substituted Carbon Network

Abstract

The on‐surface synthesis strategy has emerged as a promising route for fabricating well‐defined two‐dimensional (2D) BN‐substituted carbon nanomaterials with tunable electronic properties. This approach relies on specially designed precursors and requires a thorough understanding of the on‐surface reaction pathways. It promises precise structural control at the atomic scale, thus complementing chemical vapor deposition (CVD). In this study, we investigated a novel heteroatomic precursor, tetrabromoborazine, which incorporates a BN core and an OH group, on Ag(111) using low temperature scanning tunnelling microscopy/spectroscopy (LT‐STM/STS) and X‐ray photoelectron spectroscopy (XPS). Through sequential temperature‐induced reactions involving dehalogenation and dehydrogenation, distinct tetrabromoborazine derivatives were produced as reaction intermediates, leading to the formation of specific self‐assemblies. Notably, the resulting intricate supramolecular structures include a chiral kagomé lattice composed of molecular dimers exhibiting a unique electronic signature. The final product obtained was a random covalent carbon network with BN‐substitution and embedded oxygen heteroatoms. Our study offers valuable insights into the significance of the structure and functionalization of BN precursors in temperature‐induced on‐surface reactions, which can help future rational precursor design. Additionally, it introduces complex surface architectures that offer a high areal density of borazine cores.