The synthesis of borophene phases on metal templates has been one of the remarkable discoveries. Unlike graphitic sheet (Figure 1a), a planar traingulene sheet (Figure 1b) of boron is thought as the most probable structure initially, in several theoretical studies due to its electron deficiency. However, the binding energy (B.E) of triangulene sheet increases upon distortion from planarity (Figure 1c) or formation of hexagonal holes (Figure 1d). The recent experimental reports show a different picture. Each attempt to generate 2D boron sheets on a metal template gave a different phase, but always consisting of triangular networks. Is it possible to understand the structural diversity of borophenes drawing an isoelectronic picture to that of graphene? In this presentation, an electron counting strategy based on benzenoid aromatics will be discussed for the non-planar distortions and emergence of holes in borophenes. The stability of several model borophene structures studied using Density Functional Theory (DFT) by varying hole densities (HD) with and without the metal templates will also be presented. The molecular dynamic simulations solve the controversies of structural possibilities in every experimental attempt and the inherent determining factors. The polymorphs of 2D borophene phases are reminiscent of the variations of 3D boron allotropes.

Role of holes and non-planar distortions in borophenes, an ab-initio study

2019 Spring National Meeting

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