Highly sensitive and flexible NO₂ gas sensor based on nitro-functionalized graphene film

Area of Science:

• Materials Science
• Chemical Engineering
• Sensor Technology

Background:

• Graphene's unique electronic properties make it promising for gas sensors.
• Developing flexible sensors for environmental monitoring is crucial.
• Nitrogen dioxide (NO₂) is a harmful air pollutant requiring sensitive detection methods.

Purpose of the Study:

• To create a flexible gas sensor for nitrogen dioxide (NO₂) detection.
• To enhance the sensing performance of graphene through chemical functionalization.
• To investigate the sensor's performance at a moderate operating temperature.

Main Methods:

• Chemical modification of CVD-grown graphene films using diazonium chemistry to introduce nitro-functional groups.
• Characterization of functionalized graphene using Raman spectroscopy and X-ray photoelectron spectroscopy.
• Fabrication and testing of a flexible NO₂ gas sensor operated at 150°C.

Main Results:

• Nitro-functionalized graphene exhibited significantly enhanced response to low-concentration NO₂ compared to pristine graphene.
• The sensor demonstrated stable operation under repeated gas exposure and mechanical bending.
• Improved sensing performance is attributed to the electron-withdrawing nature of nitro groups, enhancing p-type behavior and charge transfer.

Conclusions:

• Chemical functionalization of graphene is an effective strategy to improve NO₂ sensing.
• The developed nitro-functionalized graphene sensor shows potential for flexible and wearable gas sensing applications.
• Moderate operating temperatures combined with functionalization offer a pathway for efficient NO₂ detection.