Two-Dimensional Conductive Metal−Organic Frameworks for Gas Sensors: Mechanisms and Design Strategies

Two-dimensional conductive metal-organic frameworks (2D c-MOFs) combine tunable pore structures with electronic conductivity, which demonstrate significant potential in the field of room-temperature gas sensors. This review summarizes the current understanding of the fundamental sensing mechanisms of 2D c-MOFs, including adsorption-driven charge transfer, metal-center redox activity, ligand-mediated interactions, and structure-induced modulation of electronic transport. Thereafter, a systematic, design-oriented classification of strategies for 2D c-MOFs based sensors is presented to enhance their performance, including the tuning of metal nodes and mixed ligands, control of micro and nanomorphology, noble-metal nanoparticle decoration, formation of heterostructures and composites, and usage of field-effect transistors. Additionally, the following issues are addressed to translate 2D c-MOFs from promising materials into deployed sensors: long-term stability, humidity management, and fabrication of scalable devices. Future research focuses are proposed so as to unlock the full potential of 2D c-MOFs for practical sensing applications.