Rationally designed titanium-based metal-organic frameworks for visible-light activated chemiresistive sensing

Simultaneously realizing high sensitivity and high selectivity at room temperature is still a big challenge for designing chemiresistive gas sensing materials. In this work, the first visible-light active MOF sensing material was rationally designed and prepared to meet this challenge. Different from the reported MOFs, FIR-120 combines a high stability, permanent porosity and visible light active titanium-phenol functional motif in one structure through an interpenetrating structure strategy. These features endow FIR-120 with unique photo-physic/chemistry properties that enable the highest sensitivity, lowest experimental limit-of-detection (LOD) and excellent selectivity to NO2 among all reported MOFs and MOF composite materials at room temperature. Moreover, the structure-sensing relationship is studied through experiments and theoretical calculations. This work provides guidance for the design and synthesis of high-performance visible-light active MOFs and leads to a new type of gas sensing material.