Recent Trends in Conductive Metal–Organic Framework-Based Sensors for Hazardous and Environmental Gas Detection

Conductive metal–organic frameworks (c-MOFs) have emerged as promising gas-sensing materials due to their intrinsic electrical conductivity at room temperature, high porosity, large surface area, and tunable chemical composition and structure. In particular, the presence of exposed catalytic sites—such as metal nodes and functionalized ligands—enables the binding of airborne chemical species. These interactions, through redox reactions and/or local polarity changes, induce measurable variations in electrical resistance. Common hazardous and environmental gases such as ammonia, hydrogen sulfide, nitrogen dioxide, and nitric oxide, which possess strong polarity and acid–base characteristics, are especially well-suited for detection by c-MOF-based sensors. However, the practical application of c-MOFs remains limited by their relatively low sensitivity and reversibility. These limitations can be addressed through rational compositional engineering to design fully reversible and sensitive c-MOF chemiresistors. In addition, various structural designs including the formation of hollow and hierarchical architectures in both thin films and nanoparticles have been employed to enhance sensitivity. Because many of these approaches are recent and represent first attempts within the c-MOF research field, this review aims to provide a comprehensive overview of the state-of-the-art strategies, offering design guidance for the development of room-temperature-operating gas sensors targeting hazardous and environmental gases.