Sequential Modification Strategy to Construct Crystalline Benzimidazole Covalent Organic Frameworks with Extraordinary Stability and Polymerization Degree

Jinli Li, Qiong Lei, Xinglong Dong, Cailing Chen, Xiongli Liu, Zhiyuan Zhang, Feng Shui, Mao Yi, Baiyan Li, Xian-He Bu

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

The intriguing proton-conducting and catalytic properties of benzimidazole-functionalized covalent organic frameworks (BIM-COFs) largely depend on their material quality. Here, we report a novel sequential modification (SM) strategy that enables the preparation of extraordinarily stable BIM-COFs with high polymerization degree. As a “proof of principle”, the designed TpBD-BIMSM was successfully synthesized using the SM strategy, which exhibited superior chemical stability (slight structural change after treatment in 6 M HCl or 6 M NaOH). Compared with the counterpart produced by the conventional direct condensation approach (TpBD-BIMDC), TpBD-BIMSM exhibited a higher Brunauer–Emmett–Teller (BET) surface area (213 m2 g–1 vs 52 m2 g–1) and significantly enhanced CO2, CH4, C2H6, and C2H4 uptake capacities. Furthermore, the proton conductivity of TpBD-BIMSM was measured to be 1.2 × 10–2 S cm–1, which is 2 orders of magnitude higher than that of TpBD-BIMDC (7.2 × 10–4 S cm–1) under identical conditions (80 °C and 98% RH) and also ranks it among the highest in all COF-based proton conductors. In addition, TpBD-BIMSM showed a lower activation energy (Ea) value than TpBD-BIMDC (0.16 eV vs 0.20 eV). Such high proton conductivity and low Ea value of TpBD-BIMSM can be attributed to its large surface area and high polymerization degree, which could provide extra proton transfer paths and accelerate proton movement. Furthermore, such a strategy can be readily extended to construct other BIM-COFs (TpOMe-BIMSM) that thus highlights the generality of sequential modification strategy. And this strategy thus paves a new way for constructing stable and highly polymerized BIM-COFs for related applications.
Original languageEnglish (US)
JournalChemistry of Materials
DOIs
StatePublished - May 18 2023

ASJC Scopus subject areas

  • Materials Chemistry
  • General Chemical Engineering
  • General Chemistry

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