Efficient Proton Conduction through [N···X···N]+ Halogen Bond Coordination in Halogen‐Bonded Organic Frameworks

Abstract

Advancing anhydrous proton‐conducting materials is essential for the fabrication of high‐temperature (>373 K) polymer electrolyte membrane fuel cells (HT‐PEMFCs) and remains a significant challenge. Herein, halogen‐bonded organic frameworks linked by [N···I··N]+ interactions are reported as outstanding high‐temperature conductive materials. By incorporating carbazole groups into the monomers, two highly crystalline halogen‐bonded organic frameworks (XOF‐CSP/CTP) are constructed. These XOFs exhibit a high intrinsic conductivity (σ = 1.22 × 10−3 S cm−1) under high‐temperature anhydrous conditions. Doping the XOFs with H3PO4 allows the nitrogen sites and I+ sites on the pore walls to stabilize and tightly confine the H3PO4 network within the porous framework through hydrogen bonding, thereby enhancing proton conductivity under anhydrous conditions (σ = 1.02 × 10−2 S cm−1). Temperature‐dependent curves and theoretical calculations indicate that proton transport is governed by a low‐energy barrier hopping mechanism. These materials exhibit excellent stability and maintain high proton conductivity across a broad temperature range. This work provides a new platform for designing anhydrous proton‐conducting materials with significant potential as high‐temperature proton exchange membranes.