Low-Temperature Ethanol Sensor via Defective Multiwalled Carbon Nanotubes

Area of Science:

• Materials Science
• Nanotechnology
• Chemical Engineering

Background:

• Defective carbon nanotubes (CNTs) exhibit unique properties beneficial for sensing applications.
• Catalytic chemical vapor deposition (CCVD) is a key method for fabricating tailored CNT structures.
• Defect sites on CNTs are crucial for enhancing their sensitivity to various gases.

Purpose of the Study:

• To fabricate defective multi-walled carbon nanotubes (MWCNTs) using CCVD.
• To investigate the gas sensing properties of these defective MWCNTs.
• To explore potential sensing mechanisms for improved gas detection.

Main Methods:

• Fabrication of defective MWCNTs via CCVD using Ni and Cr catalysts.
• Characterization of CNT defects using Raman spectroscopy (G-band and D-band analysis).
• Testing the gas sensing performance of the fabricated sensor towards NO, NO2, CO, acetone, and ethanol at 30 °C.

Main Results:

• Defective MWCNTs with porous and crystalline structures were successfully synthesized.
• The sensor demonstrated the highest response (8.8%) towards ethanol at 50 ppm and 30 °C.
• The sensor exhibited reliable detection of ethanol at lower concentrations (2.8% at 5 ppm) and low operating temperatures.

Conclusions:

• Defective MWCNTs are promising materials for highly sensitive and reliable gas sensors.
• The developed sensor offers power-efficient operation due to its low-temperature sensitivity to ethanol.
• Sensing mechanisms involving direct interaction and Coulomb dipole interaction are proposed for gas adsorption on the nanotube surface.