Ionic-liquid functionalized MOFs: Interfacial engineering principles for electrochemical sensing

Ionic-liquid-functionalized metal–organic frameworks (IL-functionalized MOFs) are emerging as promising electrochemical sensing interfaces. They combine the structural tunability of MOFs with the ionic conductivity and microenvironmental regulation provided by ionic liquids. This focused review critically examines IL-functionalized MOFs from an interfacial-engineering perspective, with emphasis on how IL incorporation governs charge transfer, analyte recognition, pore accessibility, and operational stability at MOF–electrode interfaces. Rather than treating reported systems as isolated examples, this review identifies recurring design principles that underpin sensing performance, including enhanced ionic/proton transport, modulation of local interfacial microenvironments, strengthened host–guest interactions, and promotion of node-assisted electron transfer. The major synthetic and processing routes used to construct these materials are comparatively assessed based on framework integrity, IL distribution, interfacial compatibility, and device manufacturability. Reported studies collectively show that IL functionalization can markedly improve sensitivity, selectivity, anti-interference behavior, and practical stability. However, these benefits remain strongly dependent on controlled IL loading and the preservation of transport-accessible porosity by integrating synthesis, mechanism, comparative performance, and practical limitations within a sensing-specific framework. This review clarifies the distinctive role of ionic liquids in MOF-based electrochemical interfaces and guides the rational design of more robust and scalable sensing platforms.