Abstract

The fabrication of crystalline 2D conjugated polymers with well-defined repeating units and in-built porosity presents a significant challenge to synthetic chemists. Yet they present an appealing target because of their desirable physical and electronic properties. Here we report the preparation of a 2D conjugated aromatic polymer synthesized via C–C coupling reactions between tetrabromopolyaromatic monomers. Pre-arranged monomers in the bulk crystal undergo C–C coupling driven by endogenous solid-state polymerization to produce a crystalline polymer, which can be mechanically exfoliated into micrometre-sized lamellar sheets with a thickness of 1 nm. Isothermal gas-sorption measurements of the bulk material reveal a dominant pore size of ~0.6 nm, which indicates uniform open channels from the eclipsed stacking of the sheets. When employed as an organic anode in an ambient-temperature sodium cell, the material allows a fast charge/discharge of sodium ions, with impressive reversible capacity, rate capability and stability metrics.

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Acknowledgements

K.P.L. acknowledges a National Research Foundation (NRF) Competitive Research Programme (CRP) grant NRF2015NRF-CRP002-006 ‘Two-dimensional Covalent Organic Framework: Synthesis and Applications’. K.P. L., S.Y.Q. and the team acknowledge the NRF, Prime Minister's Office, Singapore, under its Medium Sized Centre Programme (CA2DM). S.Y.Q. and X.L. acknowledge the Singapore NRF for funding under the NRF Fellowship (NRFNRFF2013-07). Calculations were performed on the computational cluster at CA2DM, National University of Singapore. The authors thank H. Xu, D. Y. Yu, Y. W. Peng, C. L. Su, S. J. R. Tan, S. M. Poh, X. X. Zhao, D. C. Geng and J. Y. Chen for helpful discussions.

Author information

Author notes

    • Wei Liu
    • , Xin Luo
    •  & Yang Bao

    These authors contributed equally to this work

Affiliations

  1. Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore

    • Wei Liu
    • , Yang Bao
    • , Yan Peng Liu
    • , Guo-Hong Ning
    • , Ibrahim Abdelwahab
    • , Chang Tai Nai
    •  & Kian Ping Loh
  2. Centre for Advanced 2D Materials (CA2DM), National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore

    • Wei Liu
    • , Xin Luo
    • , Yang Bao
    • , Linjun Li
    • , Su Ying Quek
    •  & Kian Ping Loh
  3. NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Centre for Life Sciences, #05-01, 28 Medical Drive, Singapore 117456, Singapore

    • Wei Liu
    • , Yang Bao
    •  & Ibrahim Abdelwahab
  4. Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive, Singapore 117585, Singapore

    • Zhi Gang Hu
    • , Dan Zhao
    •  & Bin Liu
  5. Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117551, Singapore

    • Su Ying Quek

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Contributions

K.P.L. supervised the project. W.L. and K.P.L. designed and performed the experiments. X.L. performed the theoretical calculations under the supervision of S.Y.Q. Y.B. performed the STM characterization. Y.P.L., I.A. and L.L. helped to exfoliate the sample and conduct the AFM imaging. G.H.N. helped with the crystal files analysis. C.T.N. helped to collect XPS spectra. Z.G.H. and D.Z. helped to perform Ar-sorption measurements. B.L. helped to analyse the experimental results. W.L., X.L., S.Y.Q. and K.P.L. wrote the manuscript with input from all the authors.

Competing interests

The authors declare no competing financial interests.

Corresponding authors

Correspondence to Su Ying Quek or Kian Ping Loh.

Supplementary information

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Crystallographic information files

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    Supplementary information

    Crystallographic data for 2-TBQP.

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    Supplementary information

    Crystallographic data for DDQP.

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DOI

https://doi.org/10.1038/nchem.2696