Article

A flexible metal–organic framework with a high density of sulfonic acid sites for proton conduction

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Abstract

The design of stable electrolyte materials with high proton conductivity for use in proton exchange membrane fuel cells remains a challenge. Most of the materials explored have good conductivity at high relative humidity (RH), but significantly decreased conductivity at reduced RH. Here we report a chemically stable and structurally flexible metal–organic framework (MOF), BUT-8(Cr)A, possessing a three-dimensional framework structure with one-dimensional channels, in which high-density sulfonic acid (–SO3H) sites arrange on channel surfaces for proton conduction. We propose that its flexible nature, together with its –SO3H sites, could allow BUT-8(Cr)A to self-adapt its framework under different humid environments to ensure smooth proton conduction pathways mediated by water molecules. Relative to other MOFs, BUT-8(Cr)A not only has a high proton conductivity of 1.27 × 10−1 S cm−1 at 100% RH and 80 °C but also maintains moderately high proton conductivity at a wide range of RH and temperature.

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Acknowledgements

This work was financially supported by the National Natural Science Fund for Innovative Research Groups (51621003), the Natural Science Foundation of China (No. 21576006, 21606006), the Importation and Development of High-Caliber Talents Project of Beijing Municipal Institutions (CIT&TCD20150309) and the Welch Foundation (AX-1730).

Author information

Affiliations

  1. Beijing Key Laboratory for Green Catalysis and Separation and Department of Chemistry and Chemical Engineering, College of Environmental and Energy Engineering, Beijing University of Technology, Beijing, 100124, China

    • Fan Yang
    • , Yibo Dou
    • , Bin Wang
    • , Heng Zhang
    •  & Jian-Rong Li
  2. State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian, 350002, China

    • Gang Xu
  3. NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland, 20899-6102, USA

    • Hui Wu
    •  & Wei Zhou
  4. Fujian Provincial Key Laboratory of Polymer Materials, College of Materials Science and Engineering, Fujian Normal University, Fuzhou, Fujian, 350007, China

    • Banglin Chen
  5. Department of Chemistry, University of Texas at San Antonio, One UTSA Circle, San Antonio, Texas, 78249-0698, USA

    • Banglin Chen

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Contributions

J.-R.L. and F.Y. conceived the research idea and designed the experiments. F.Y. performed most of the experiments and analysed data. B.W. participated in the structural determination of MOFs. H.Z. participated in the preparation of MOFs. Y.D. participated in the proton conduction measurement. H.W. and W.Z. performed the PXRD and Le Bail refinements. J.-R.L., B.C., H.W., W.Z., G.X. and F.Y. discussed and co-wrote the paper. All authors discussed the results and commented on the manuscript.

Competing interests

The authors declare no competing financial interests.

Corresponding authors

Correspondence to Jian-Rong Li or Banglin Chen.

Electronic supplementary material

  1. Supplementary Information

    Supplementary Figures 1–41, Supplementary Tables 1–3, Supplementary References

  2. Supplementary Data 1

    Crystallographic information for BUT-8(Al)