Graphene-Modified ZnO Nanostructures for Low-Temperature NO₂ Sensing

Area of Science:

• Materials Science
• Nanotechnology
• Chemical Engineering

Background:

• Gas sensors are crucial for environmental monitoring and safety.
• Developing highly sensitive and selective gas sensors remains a challenge.
• Metal oxide/graphene nanocomposites offer promising properties for gas sensing.

Purpose of the Study:

• To develop a novel method for synthesizing wrapped ZnO/reduced graphene oxide (rGO) nanocomposites.
• To investigate the gas-sensing properties of these nanocomposites, particularly for NO2.
• To understand the role of the Schottky junction in enhancing gas-sensing performance.

Main Methods:

• Ultrasonic spray-assisted solvothermal (USS) synthesis of ZnO/rGO nanocomposites.
• Characterization using various analytical techniques.
• Evaluation of gas-sensing properties for NO2 and VOCs at different operating temperatures.

Main Results:

• USS-derived ZnO/rGO exhibited superior NO2-sensing performance at low temperatures (70-130 °C) compared to traditional methods.
• The optimal ZnO/rGO-0.5 sample showed a response of 62 at 130 °C, three times that of pure ZnO.
• A low detection limit of 10 ppb for NO2 and high selectivity were achieved.
• Enhanced sensing is attributed to high specific surface area, porous structures, and formed Schottky junctions.

Conclusions:

• The novel USS method effectively synthesizes wrapped ZnO/rGO nanocomposites.
• These nanocomposites demonstrate excellent NO2-sensing capabilities, including high sensitivity, low detection limit, and selectivity.
• The formation of ZnO/rGO Schottky junctions is key to the improved gas-sensing performance.