Imidazole encapsulated in core–shell MOF@COFs with a high anhydrous proton conductivity

Abstract

Proton-conductive materials are the most important components in fuel cells. At present, there are still significant challenges for the controllable design of anhydrous proton electrolytes with high conductivity at high temperature (>80 °C). Herein, we propose proton conduction across heterogeneous channels in a metal–organic framework/covalent–organic framework hybrid (MOF@COF). The imidazole molecules are encapsulated into core–shell UiO-67@TAPB–DMTP-COFs (TAPB = 1,3,5-tri(4-aminophenyl)benzene, DMTP = 2,5-dimethoxyterephthalaldehyde), and they achieve the highest anhydrous proton conductivity (σ = 1.4 × 10⁻² S cm⁻¹ at 120 °C) with an ultra-low activation energy. The synergism of porous MOF@COF heterostructures is of great significance for improving proton conduction, which is due to the rearrangement of hydrogen bonds and the enhanced transport of protons across the unique heterogeneous channels. This work provides a novel platform based on a MOF@COF hybrid for high-temperature anhydrous proton conduction.