Metal–Organic-Framework-Decorated Carbon Nanofibers with Enhanced Gas Sensitivity When Incorporated into an Organic Semiconductor-Based Gas Sensor

Because of their high porosity, metal-organic framework (MOF) materials have attracted much attention for use in gas-sensing applications. However, problems with the processability of MOFs for use in reliable gas-sensing electronics remain unsolved. Herein, combination of the strong gas-adsorbing properties of MOF nanomaterials and organic thin-film transistor-type chemical sensors is proposed and experimentally demonstrated. The hybrid blend system with inorganic MOF nanomaterials and organic semiconductors likely exhibits thermodynamic instability because of each phase's self-aggregation, which is difficult to settle without surface functionalization. We propose a novel method to produce an inorganic-organic hybrid sensor by introducing carbon nanofibers as a scaffold. We demonstrate that the carbon nanofibers perform dual functions: enabling the attachment of MOF nanoparticles at the fiber surface, which stabilizes the nanoparticle-embedded polymer layer, and maintaining reliable conductivity for improved gas-sensing performance. On the basis of our characterization of their nanomorphology and nanocrystal structure, the MOF nanoparticles and carbon nanofibers are shown to render a hybrid core-shell structure in the conjugated polymer matrix. This organic-inorganic hybrid system was incorporated into a field-effect transistor device to detect hazardous NO₂ gas analytes, operating in real-time with high responsivity. The prototype chemical sensor holds enormous promise for other chemical sensors.