Design and Functionalization Strategy of Porous Liquids: From Structural Construction to Application Expansion

Porous liquids (PLs) represent a transformative class of materials that integrate permanent porosity with fluidic behavior, offering unprecedented opportunities for molecular transport, adsorption, and catalysis. This review systematically explores the design strategies, structural features, and functionalization approaches of PLs derived from diverse precursors such as MOFs, COFs, MOCs, HCSs, and zeolites. A central challenge lies in maintaining pore accessibility while preserving fluidity and system stability. Among PL types, MOF-based PLs exhibit exceptional tunability and application potential due to the synergistic integration of metal-organic frameworks and ionic liquids. The paper further examines porosity characterization methods, highlighting the advantages of positron annihilation lifetime spectroscopy (PALS) and nuclear magnetic resonance (NMR) in resolving nanoscale pore structures despite their limitations in cost and scope. We discuss interface engineering strategies that enhance PLs' adsorption performance under pressure and showcase their multifunctional applications, from gas separation and desulfurization to biomedicine and flame retardancy. Finally, key scientific challenges and future directions are outlined, including optimizing fluidity-porosity balance, advancing multiscale characterization, and expanding PLs into emerging functional domains such as electrocatalysis and smart materials.