Dual-MOF-Layered Films via Solution Shearing Approach: A Versatile Platform for Tunable Chemiresistive Sensors

Area of Science:

• Materials Science
• Chemical Engineering
• Nanotechnology

Background:

• Metal-organic frameworks (MOFs) offer high porosity and chemical diversity, making them suitable for gas sensing.
• Low electrical conductivity of traditional MOFs limits their use in chemiresistive sensors.
• Electrically conductive MOFs (cMOFs) overcome conductivity limitations, but designing specific sensing properties remains difficult.

Purpose of the Study:

• To develop a novel MOF-on-cMOF sensor architecture for enhanced gas detection.
• To explore the synergistic integration of cMOFs with conventional MOFs for tunable sensing properties.
• To elucidate the structure-property relationships governing the performance of these composite sensors.

Main Methods:

• Fabrication of layered MOF-on-cMOF thin films using a two-step solution-shearing method.
• Strategic selection and deposition of conventional MOF layers with tailored pore structures and adsorption properties onto cMOF films.
• Gas sensing performance evaluation for analytes including NH3, H2S, and NO2.
• Computational analysis to understand underlying structure-property relationships.

Main Results:

• Successful fabrication of tunable MOF-on-cMOF layered sensors.
• Demonstrated enhancement in sensitivity, selectivity, response speed, and recovery for target gases.
• Observed sensing improvements beyond the conventional role of MOFs as sieving layers.
• Computational insights into the rational design principles for MOF-based gas sensors.

Conclusions:

• The MOF-on-cMOF composite strategy offers a viable route for designing high-performance gas sensors.
• Synergistic integration of different MOFs in layered structures unlocks tunable sensing capabilities.
• Understanding structure-property relationships is crucial for the rational design of next-generation MOF-based chemiresistive sensors.