Abstract
Hydroxide anion transport is essential for alkaline fuel cells, but hydroxide anion has an inherently low conductivity owing to its small diffusion coefficient and high mass. Ordered open channels found in covalent organic frameworks are promising as pathways to enable hydroxide anion transport, but this remains to be explored. Here we report designed synthesis of anionic covalent organic frameworks that promote hydroxide anion transport across the one-dimensional channels. Engineering cationic chains with imidazolium termini onto the pore walls self-assembles a supramolecular interface of single-file hydroxide anion chains in the channels. The frameworks facilitate hydroxide anion transport to achieve an exceptional conductivity of 1.53 × 10-2 S cm-1 at 80 °C, which is 2-6 orders of magnitude higher than those of linear polymers and other porous frameworks. Impedance spectroscopy at different temperatures and studies on deuterated samples reveal that hydroxide anions transport via a proton-exchange hopping mechanism. These results open a way to design framework materials for energy conversions via engineering an anionic interface.
Original language | English |
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Pages (from-to) | 8970-8975 |
Number of pages | 6 |
Journal | Journal of the American Chemical Society |
Volume | 143 |
Issue number | 24 |
DOIs | |
State | Published - Jun 23 2021 |
Funding
D.J. acknowledges the MOE tier 1 grant (R-143-000-A71-114) and NUS start-up grant (R-143-000-A28-133). Y.H. acknowledges JSPS Grant-in-Aid for Scientific Research on Innovative Areas (Coordination Asymmetry), Grant No. JP19H04570. H.X. acknowledges the support from the National Natural Science Foundation of China (52073161) and Tsinghua University-Zhangjiagang Joint Institute for Hydrogen Energy and Lithium-Ion Battery Technology. S.I. acknowledges support by the Laboratory Directed Research and Development (LDRD) Program of Oak Ridge National Laboratory. ORNL is managed by UT-Battelle, LLC, for DOE under contract DE-AC05-00OR22725. We thank Naohiro Obokata for computing.
Funders | Funder number |
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Tsinghua University-Zhangjiagang Joint Institute for Hydrogen Energy and Lithium-Ion Battery Technology | |
U.S. Department of Energy | DE-AC05-00OR22725 |
Oak Ridge National Laboratory | |
Laboratory Directed Research and Development | |
National University of Singapore | R-143-000-A28-133 |
Ministry of Education - Singapore | R-143-000-A71-114 |
Japan Society for the Promotion of Science | JP19H04570 |
National Natural Science Foundation of China | 52073161 |