Construction of dense H-bond acceptors in the channels of covalent organic frameworks for proton conduction

Abstract

The design of high-conductivity proton exchange membranes (PEMs) under high-temperature anhydrous conditions is important for fuel cells. Covalent organic frameworks (COFs) are a class of promising templates for proton conduction because their one-dimensional porous channels provide a fast pathway for proton transport. Herein, we have demonstrated two two-dimensional (2D) COFs with different densities of oxygen atoms along the pore walls as a host with H₃PO₄ loading for proton conduction. The O atoms facilitated the formation of the hydrogen-bond networks along the pores, further facilitating proton transport. The COF (PA@PyTTA-BMTP-COF) with 12 O atoms in each pore showed a proton conductivity of 26.00 mS cm⁻¹, which was three times that of the COF (PA@PyTTA-DHTA-COF) with four atoms in each pore at 140 °C under anhydrous conditions. This work gives us a new platform to design porous channels for ionic conduction.