PANa/Covalent organic framework composites with improved water uptake and proton conductivity

Abstract

It is a challenge to effectively load proton carriers in COFs to improve their proton conductivity. Herein, we report a series of COF-based composites, PANa@UCOF-x (PANa: sodium polyacrylate, x: weight percentage of PANa), which were prepared by coating different proportions of superabsorbent PANa on the COF surface based on an in situ reaction strategy. Since PANa can greatly enhance the enrichment of water molecules in one-dimensional (1D) channels of COFs, these COF-based composites exhibit superprotonic conduction. At 80 °C and 95% relative humidity (RH), the proton conductivity of PANa@UCOF-10, PANa@UCOF-28 and PANa@UCOF-40 reaches 1.6 × 10⁻², 5.1 × 10⁻², and 1.1 × 10⁻¹ S cm⁻¹, respectively, which is 4–5 orders of magnitude higher than 7.4 × 10⁻⁷ S cm⁻¹ of the original UCOF. This work not only develops a new method to improve the water content of the COF channels, but also proves the important role of ordered channels in constructing effective proton conduction pathways.