Sulfonated 2D Covalent Organic Frameworks for Efficient Proton Conduction

Open 1D channels found in covalent organic frameworks are unique and promising to serve as pathways for proton conduction; how to develop high‐rate yet stable transporting systems remains a substantial challenge. Herein, this work reports a strategy for exploring proton‐conducting frameworks by engineering pore walls and installing proton‐containing polymers into the pores. Amide‐linked and sulfonated frameworks were synthesized from imine‐linked precursors via sequentially engineering to oxidize into amide linkages and to further anchor sulfonic acid groups onto the pore walls, enabling the creation of sulfonated frameworks with high crystallinity and channel ordering. Integrating sulfonated polyether ether ketone chains into the open channels enables proton hopping to across the channels, greatly increases proton conductivity and enables a stable continuous run. These results suggest a way to explore proton‐conducting COFs via systematic engineering of the wall and space of the open nanochannels. Highly crystalline sulfonated COFs annulated with cyclic ether moieties were constructed by direct post‐synthetic sulfonation for the first time. Sulfonated polyether ether ketone (SPEEK) was further infiltrated into the 1D regular channels of these sulfonated COFs to improve the proton conductivity and reduce the loss of protons (H+). The resulting hybrid material achieves excellent proton conductivity up to 6.22×10−3 S cm−1.