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Synthesis of bilayer borophene

Nature Chemistry volume 14, pages 25–31 (2022)Cite this article

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Abstract

As the nearest-neighbour element to carbon, boron is theoretically predicted to have a planar two-dimensional form, named borophene, with novel properties, such as Dirac fermions and superconductivity. Several polymorphs of monolayer borophene have been grown on metal surfaces, yet thicker bilayer and few-layer nanosheets remain elusive. Here we report the synthesis of large-size, single-crystalline bilayer borophene on the Cu(111) surface by molecular beam epitaxy. Combining scanning tunnelling microscopy and first-principles calculations, we show that bilayer borophene consists of two stacked monolayers that are held together by covalent interlayer boron–boron bonding, and each monolayer has β12-like structures with zigzag rows. The formation of a bilayer is associated with a large transfer and redistribution of charge in the first boron layer on Cu(111), which provides additional electrons for the bonding of additional boron atoms, enabling the growth of the second layer. The bilayer borophene is shown to possess metallic character, and be less prone to being oxidized than its monolayer counterparts.

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Fig. 1: STM images showing the evolution of the Cu(111) surface with increasing B coverage.
Fig. 2: High-resolution STM images and structural models of monolayer and bilayer borophene on Cu(111).
Fig. 3: Charge distribution between bilayer borophene and the Cu(111) substrate.
Fig. 4: The anti-oxidation ability and electronic structures of borophene on Cu(111).

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Data availability

Data that support the finding of this study are available within the article and its Supplementary Information and data files. Data for the Supplementary figures and DFT-calculated structures are provided as Supplementary Data files. Source data are provided with this paper.

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Acknowledgements

This work was financially supported by the National Key R&D Program of China (2018YFE0202700, 2016YFA0200602, 2016YFA0300904 and 2016YFA0202301), the National Natural Science Foundation of China (12134019, 22073087, 11825405, 21573204 and 21890751), the Beijing Natural Science Foundation (Z180007), the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB30000000 and XDB01020300), the Anhui Initiative in Quantum Information Technologies (AHY090400), the National Program for Support of Top-notch Young Professional, NSFC-MAECI (51861135202) and the Super Computer Centre of USTCSCC and SCCAS.

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  1. These authors contributed equally: Caiyun Chen, Haifeng Lv.

Authors and Affiliations

  1. Institute of Physics, Chinese Academy of Sciences, Beijing, China

    Caiyun Chen, Ping Zhang, Yu Wang, Chen Ma, Wenbin Li, Xuguang Wang, Baojie Feng, Peng Cheng, Kehui Wu & Lan Chen

  2. School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, China

    Caiyun Chen, Ping Zhang, Yu Wang, Chen Ma, Wenbin Li, Xuguang Wang, Baojie Feng, Peng Cheng, Kehui Wu & Lan Chen

  3. Hefei National Laboratory for Physical Sciences at the Microscale, Synergetic Innovation of Quantum Information and Quantum Technology, CAS Center for Excellence in Nanoscience, and School of Chemistry and Materials Sciences, University of Science and Technology of China, Hefei, China

    Haifeng Lv, Zhiwen Zhuo & Xiaojun Wu

  4. Songshan Lake Materials Laboratory, Dongguan, China

    Kehui Wu & Lan Chen

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Contributions

L.C. and K.W. designed and conceived this research. C.C., W.L., X.W., P.Z., C.M. and Y.W. performed the experiments under the supervision of L.C. and K.W. H.L. and Z.Z. did the calculation works under the supervision of X.W. B.F. and P.C. participated in the data analysis and discussion. All the authors contributed to the writing of the manuscript.

Corresponding authors

Correspondence to Xiaojun Wu, Kehui Wu or Lan Chen.

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Peer review information Nature Chemistry thanks Prashant Kumar and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary information

Supplementary Information

Supplementary Figs. 1–20, Discussion and Table 1.

Supplementary Data 1

Raw data of graphs in Supplementary Figs. 4, 17 and 19.

Supplementary Data 2

Structural models of borophene shown in the main text and the Supplementary Information.

Source data

Source Data Fig. 3

Raw data of planar-averaged electron density difference for B/Cu in Fig. 3.

Source Data Fig. 4

Raw data of all graphs in Fig. 4.

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Chen, C., Lv, H., Zhang, P. et al. Synthesis of bilayer borophene. Nat. Chem. 14, 25–31 (2022). https://doi.org/10.1038/s41557-021-00813-z

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