Continuous MOF Membrane-Based Sensors via Functionalization of Interdigitated Electrodes

Area of Science:

• Materials Science
• Nanotechnology
• Chemical Sensing

Background:

• Metal-organic frameworks (MOFs) offer tunable properties for gas sensing applications.
• Thin film fabrication is crucial for developing efficient and miniaturized sensors.
• Direct electrical detection of nitrogen dioxide (NO2) is important for environmental monitoring.

Purpose of the Study:

• To synthesize M-MOF-74 (M = Co, Mg, Ni) thin film membranes for NO2 gas sensing.
• To investigate the electrical properties of these MOF membranes upon NO2 exposure.
• To evaluate the performance of Ni-MOF-74 as a NO2 gas sensor.

Main Methods:

• Surface functionalization of glass/Pt interdigitated electrodes.
• Synthesis of M-MOF-74 thin films via a two-step procedure.
• Characterization using infrared spectroscopy, scanning electron microscopy (SEM), and X-ray diffraction (XRD).
• Electrical detection of NO2 using impedance measurements.

Main Results:

• Uniform thin film membranes of Ni- and Mg-MOF-74 were successfully grown.
• Ni-MOF-74 membranes exhibited a 123x decrease in impedance magnitude upon exposure to 5 ppm NO2 over 4 hours.
• The MOF membranes showed a faster response and larger impedance change compared to bulk materials.
• Continuous, overlapping growth was sufficient for sensor functionality, even with minor defects.

Conclusions:

• M-MOF-74 thin film membranes can be effectively synthesized for direct electrical NO2 detection.
• Ni-MOF-74 thin films demonstrate promising sensing performance for NO2 gas.
• The developed MOF-based sensor offers advantages in response time and signal change over bulk materials.