MOF Ceramic‐Like Membrane With High Proton Conduction and Tunable Transparency

The industrial deployment of metal-organic frameworks (MOFs) is hindered by their particulate morphology, while the fabrication of macroscopic architectures-particularly continuous membranes remain a major challenge. Traditional approaches, such as matrix blending, vitrification, or substrate-supported deposition, often sacrifice MOF loading amount, crystallinity, porosity, or mechanical integrity. Here, we present a breakthrough strategy based on OH-bridging (i.e., using metal─OH-metal bonds to connect nanoparticles) for fabricating MOF ceramic-like membrane, which endows the membranes with pure MOF composition, ordered porous structure, and self-supporting capability. The prepared membrane demonstrates remarkable proton conduction and humidity-responsive optical transparency, which stems from its compact grain boundary structure and the strong grain boundary-water interactions. This OH-bridging strategy overcomes a critical challenge in metal-organic frameworks: the inability to process powdered MOFs into freestanding, crystalline porous membranes, which is beneficial for bridging the gap between nanoscale design and macroscopic functional systems.