Precise Chemical Construction of Two-Dimensional Boron Materials

This project aims to establish the chemical synthetic strategy for the precise construction of two-dimensional (2D) boron materials. Numerous theoretical studies confirm that 2D boron materials, namely borophene, exhibit a metallic feature concomitant with a low density, a high melting point, large bulk modulus, a high hardness, and high thermal conductivity. These nature indicate the prospect of borophene in nanodevice applications such as electronics, superconductors, sensors, magnetic memory, energy storage, and battery. Despite the reserved exciting properties of borophene as next-generation materials, only a few of the experimental realization have been described so far, and its synthesis remains highly challenging. This is because the use of elemental boron with a high melting point/poor solubility as the starting material hampers the controlled growth of freestanding boron monolayer by the extant methods. In this project, we develop an efficient synthetic methodology as the bottom-up approach for the chemical synthesis of 2D boron materials. By employing Lewis bases (L) as the supporting ligands, various small boron clusters Bn(0) in the zero oxidation state can be synthesized. We use them as the core frameworks as well as boron transfer reagents for the precise construction of 2D boron materials. In stark contrast to elemental boron, the Lewis base-stabilized boron zero species Bn(0)Lm can be dissolved in various organic solvents owing to the presence of the organic Lewis base ligands, which allows for the stoichiometric chemical reaction in solution. Because a variety of Lewis bases are available, as well as, the chemical reaction conditions are finely tunable, the stepwise and controlled growth of 2D boron materials in terms of the distinct structures (length, width, and shape), can be achievable under the mild reaction conditions. Thus, this project may allow for the controlled synthesis of high-quality and fabricable borophene in a scalable manner, which will provide a significant platform for practical applications of borophene.