Subnanometer Nanowire‐Reinforced Construction of COF‐Based Membranes with Engineering Biomimetic Texture for Efficient and Stable Proton Conduction

Abstract Achieving rapid ion transport through nanochannels is essential for both biological and artificial membrane systems. Covalent organic frameworks (COFs) with well‐defined nanostructures hold great promise for addressing the above challenge. However, due to the limited processability and inadequate interlamellar interaction of COF materials, it is extremely difficult to integrate them to prepare high‐performance proton conductors. Herein, inspired by the ingenious bio‐adhesion strategy in nature, ultrafast proton conduction is achieved by taking advantage of COF membranes where TP‐COF nanosheets are linked by subnanometer nanowires/lignocellulosic nanofibrils composites (SNWs/LCNFs) through electrostatic and π‐π interactions to form an ordered and robust structure. Notably, the synthesized SNWs exhibited impressive proton conductivity and adhesion capacity due to their inbuilt phosphotungstic acid (HPW) molecules and multidimensional interactions. Therefore, attributed to the synergistic contribution of TP‐COFs and SNWs, the composite membrane achieves ultrahigh proton conductivity (0.395 S cm −1 at 80 °C and 100% RH), superior mechanical property (109.8 MPa), exceptional fuel cell performance (71.6 mW cm −2 ), and superior operational stability (OCV decay rate is about 1.5 mV h −1 ), demonstrating outstanding competitiveness. More importantly, the proposed design concept has the potential to be applied in membranes for various electrochemical devices and molecular separations.