Borophane Polymorphs

• DOI: 10.1021/acs.jpclett.1c03827
• Publication Date: 2022-01-26T14:50:19Z
• Authors: Ying Xu; Peikun Zhang; Xiaoyu Xuan; Minmin Xue; Zhuhua Zhang; Wanlin Guo; Boris I. Yakobson
• Keywords: Cluster expansion; Lattice (music)

Hydrogenated borophenes─borophanes─have recently been synthesized as a new platform for studying low-dimensional borides, but most of their lattice structures remain unknown. Here, we determine the borophane polymorphs on Ag(111) by performing extensive structural search using cluster expansion method augmented with first-principles calculations. Our results reveal rich whose stability depends hydrogen pressure. At relatively low pressures, rhombic patterns two-center-two-electron B-H bonds are energetically preferred, in excellent agreement two experimentally observed phases. In wider range structure combination and three-center-two-electron B-H-B is deep global minimum, rationalizing its experimental prevalence. For all these polymorphs, "skin" raises energy barriers oxidation above 1.1 eV, while work functions can be reduced more than 0.5 eV through varying coverage.