Ultrahigh Anhydrous Proton Transport in Imidazole-Confined Thiol-Functionalized Metal-Organic Frameworks

Developing porous solid-state proton conductors with high conductivity under anhydrous conditions is critical for fuel cell technology. Here, based on a chemically stable thiol-containing Zr-based metal-organic framework (Zr-DMSA), a superior anhydrous proton transport hybrid material (Im@Zr-DMSA) has been designed by hosting it with imidazole. Benefiting from the abundant thiol groups, permanent porosity, and robust three-dimensional framework of Zr-DMSA, the imidazole-confined Im@Zr-DMSA exhibits a wide-temperature range duration from 40 to 130 °C, showing superior proton conductivity of 1.14 × 10-3 S·cm-1 at 40 °C and 2.49 × 10-1 S·cm-1 at 130 °C. The achieved high anhydrous proton conductivity ranks as the highest value among MOF-based anhydrous proton-conducting materials and one of the top values for reported proton-conducting materials. Besides, the proton conduction mechanism and synergistic functions of the imidazole and thiol groups are systematically investigated using theoretical calculations and experimental characterizations. This work provides an important advance toward high-performance anhydrous solid-state proton conductors over a wide-temperature range.