The recent experimental realization of 2D boron (i.e., ‘borophene') has spurred broad interest in its unique material attributes such as in-plane anisotropy, seamless phase intermixing, high mechanical strength and flexibility, massless Dirac fermions, and phonon-mediated superconductivity. The polymorphic nature of borophene, which is rooted in the rich bonding configurations among boron atoms, further distinguishes it from other 2D materials and offers an additional means for tailoring its material properties. This presentation will explore the ultrahigh vacuum synthesis and atomic-scale characterization of borophene on noble metal substrates. In addition to distinct borophene polymorphs, conditions for forming self-assembled intermixed phases, superlattices, and bilayers will be delineated (1). By exploiting spatially inhomogeneous surface chemistry, seamless 2D heterointerfaces can also be realized between borophene and other materials including organic semiconductors, graphene, and graphene nanoribbons. In an effort to further tune the chemical and electronic properties of 2D boron, covalent hydrogenation of borophene has been achieved, resulting in a series of ‘borophane' polymorphs that possess significantly higher stability in ambient conditions compared to pristine borophene (2). Overall, this work establishes a series of design rules for manipulating and integrating 2D boron into a range of next-generation electronic and quantum technologies (3).

(1) X. Liu, et al., Nature Materials, 21, 35 (2022).

(2) Q. Li, et al., Science, 371, 1143 (2021).

(3) V. K. Sangwan, et al., Nature Nanotechnology, 15, 517 (2020).