Oriented construction of efficient intrinsic proton transport pathways in MOF-808

Abstract

The development of advanced materials needs to be continuously promoted by the cyclic process of mastering the structure–activity relationship, designing the experimental scheme, measuring the performance and feeding back the design ideas. Therefore, understanding the proton conduction mechanism and orientally constructing efficient intrinsic proton transport pathways are very important for the research and development of proton conductors. Herein, we propose an effective and feasible strategy of replacing the formates and hydroxide groups coordinated with Zr in MOF-808 with 1H-imidazole-4-carboxylic acid (IMC) and 4,5-imidazoledicarboxylic acid (IMDC) containing imidazole groups to synthesize MOF-808-IMC and MOF-808-IMDC. The proton conduction performances of MOF-808-IMC and MOF-808-IMDC are much higher than that of the original MOF-808. Specifically, MOF-808-IMDC exhibits an intrinsic proton conductivity of 1.11 × 10⁻² S cm⁻¹ at 80 °C and 98% RH, which can be comparable with the performances of commercial perfluorosulfonic acid resin and other MOF-based proton conductors. It is also noted that the proton conductivity of MOF-808-IMDC has good cycling stability and durability, which suggests that it has the potential to be used as a PEM. Furthermore, the proton transfer mechanism has been clarified in detail, which can provide a theoretical basis for the preparation of excellent proton conductors.