Recent advances and perspectives in proton-conducting metal-organic framework membranes

Metal-organic frameworks (MOFs), owing to their tunable pore environments and abundant hydrogen-bonding sites that enable the formation of continuous transport pathways, are widely regarded as promising candidates for proton-conducting material. Despite extensive research, most efforts have been devoted to bulk forms, such as powders and single crystals, which are hindered by long diffusion pathways, random orientation, and limited processability, thereby restricting their intergration into device. Recent progress in fabricating high-quality MOF membranes has addressed these challenges, while preserving high proton conductivity. Although notable progress has been achieved, a systematic review of proton-conducting MOF membranes remains absent. In this review, we present a comprehensive overview of proton-conducting MOF membranes, encompassing design strategies, conduction mechanisms, systematic classification, representative fabrication approaches, and their application. Particular emphasis is given to their broader application landscape, extending beyond proton exchange membrane fuel cells to include light-controlled protonic devices, proton sensors, protonic field-effect transistors, and proton rectifiers. By consolidating advances and outlining remaining challenges, this review aims to clarify design principles and guide future research toward integrating MOF membranes into next-generation protonic technologies.