Resolving the Chemically Discrete Structure of Synthetic Borophene Polymorphs

Gavin P. Campbell, Andrew J. Mannix, Jonathan D. Emery, Tien Lin Lee, Nathan P. Guisinger, Mark C Hersam, Michael J. Bedzyk

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

Atomically thin two-dimensional (2D) materials exhibit superlative properties dictated by their intralayer atomic structure, which is typically derived from a limited number of thermodynamically stable bulk layered crystals (e.g., graphene from graphite). The growth of entirely synthetic 2D crystals, those with no corresponding bulk allotrope, would circumvent this dependence upon bulk thermodynamics and substantially expand the phase space available for structure-property engineering of 2D materials. However, it remains unclear if synthetic 2D materials can exist as structurally and chemically distinct layers anchored by van der Waals (vdW) forces, as opposed to strongly bound adlayers. Here, we show that atomically thin sheets of boron (i.e., borophene) grown on the Ag(111) surface exhibit a vdW-like structure without a corresponding bulk allotrope. Using X-ray standing wave-excited X-ray photoelectron spectroscopy, the positions of boron in multiple chemical states are resolved with sub-angström spatial resolution, revealing that the borophene forms a single planar layer that is 2.4 Å above the unreconstructed Ag surface. Moreover, our results reveal that multiple borophene phases exhibit these characteristics, denoting a unique form of polymorphism consistent with recent predictions. This observation of synthetic borophene as chemically discrete from the growth substrate suggests that it is possible to engineer a much wider variety of 2D materials than those accessible through bulk layered crystal structures.

Original languageEnglish
Pages (from-to)2816-2821
Number of pages6
JournalNano Letters
Volume18
Issue number5
DOIs
Publication statusPublished - May 9 2018

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Polymorphism
Graphite
polymorphism
Van der Waals forces
trucks
standing waves
atomic structure
engineers
crystals
graphene
x rays
graphite
spatial resolution
photoelectron spectroscopy
engineering
thermodynamics
Crystals
crystal structure
predictions
Graphene

Keywords

  • boron
  • borophene
  • two-dimensional materials
  • X-ray photoelectron spectroscopy
  • X-ray standing wave

ASJC Scopus subject areas

  • Bioengineering
  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanical Engineering

Cite this

Campbell, G. P., Mannix, A. J., Emery, J. D., Lee, T. L., Guisinger, N. P., Hersam, M. C., & Bedzyk, M. J. (2018). Resolving the Chemically Discrete Structure of Synthetic Borophene Polymorphs. Nano Letters, 18(5), 2816-2821. https://doi.org/10.1021/acs.nanolett.7b05178

Resolving the Chemically Discrete Structure of Synthetic Borophene Polymorphs. / Campbell, Gavin P.; Mannix, Andrew J.; Emery, Jonathan D.; Lee, Tien Lin; Guisinger, Nathan P.; Hersam, Mark C; Bedzyk, Michael J.

In: Nano Letters, Vol. 18, No. 5, 09.05.2018, p. 2816-2821.

Research output: Contribution to journalArticle

Campbell, GP, Mannix, AJ, Emery, JD, Lee, TL, Guisinger, NP, Hersam, MC & Bedzyk, MJ 2018, 'Resolving the Chemically Discrete Structure of Synthetic Borophene Polymorphs', Nano Letters, vol. 18, no. 5, pp. 2816-2821. https://doi.org/10.1021/acs.nanolett.7b05178
Campbell, Gavin P. ; Mannix, Andrew J. ; Emery, Jonathan D. ; Lee, Tien Lin ; Guisinger, Nathan P. ; Hersam, Mark C ; Bedzyk, Michael J. / Resolving the Chemically Discrete Structure of Synthetic Borophene Polymorphs. In: Nano Letters. 2018 ; Vol. 18, No. 5. pp. 2816-2821.
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