Machine Learning Aided Understanding of the Interaction in Borophene-Boride Hetero-Structures

Borophene is unusual among two-dimensional (2D) materials for the lack of a bulk layered counterpart, resulting in novel properties which are not inherited and cannot be predicted from bulk boron, as well as polymorphic phases which enrich its properties. Also, its metallicity is unusual within the 2D materials family and enriches the diversity of available materials properties. However, the application of borophene is limited by the lack of achievement of freestanding borophene. It’s difficult to lift borophene from the substrates due to the strong interaction between them. Thus it is important to search for optimal substrates for borophene synthesis and separation. Recently, it was reported that boride is formed through the reconstruction of the top metal layer mixed with boron during borophene synthesis on Al(111) [1]. Metal borides have the potential to be superior substrates, compared to metals, for borophene synthesis and separation. The understanding of the interaction in borophene-boride hetero-structures would assist the search of optimal substrates as well as reveal the synthesis mechanism. What borides surfaces are optimal substrates for borophene synthesis? What intrinsic properties of borides dominantly affect the interaction in borophene-boride hetero-structures? How does the charge transfer between borophene and borides affect the interaction? Here we explore these questions through machine learning and density functional theory calculations of their structures, binding energies, and charge transfer. This work allows us to explore alternative routes of borophene synthesis.<br/><br/>Acknowledgements:<br/>We acknowledge funding from the National Science Foundation MRSEC program under grant number DMR-1720139. Use of the Center for Nanoscale Materials, an Office of Science user facility, was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.<br/><br/>Reference:<br/>[1] Alexei B. Preobrajenski, Andrey Lyalin, Tetsuya Taketsugu, Nikolay A. Vinogradov, and Alexander S. Vinogradov., “Honeycomb Boron on Al(111): From the Concept of Borophene to the Two-Dimensional Boride.” <i>ACS Nano</i> 2021 15 (9), 15153-15165.