Excellent Room-Temperature NO₂ Gas-Sensing Properties of TiO₂-SnO₂ Composite Thin Films Under Light Activation

Area of Science:

• Materials Science
• Nanotechnology
• Chemical Sensing

Background:

• Developing highly sensitive and stable gas sensors is crucial for environmental monitoring and industrial safety.
• Nanocomposite materials offer unique properties for enhanced gas sensing performance.

Purpose of the Study:

• To synthesize and characterize thin TiO2-SnO2 nanocomposite films for NO2 gas detection.
• To investigate the relationship between material structure, heterojunctions, and gas-sensing properties.
• To evaluate the sensor's performance under varying conditions, including low-intensity radiation.

Main Methods:

• Oxidative pyrolysis for film synthesis.
• X-ray photoelectron spectroscopy, HRTEM, and EDX for structural and compositional analysis.
• Kelvin probe force microscopy for surface potential measurements.

Main Results:

• Successful synthesis of TiO2-SnO2 nanocomposite films with n-n heterojunctions.
• The 3TiO2-97SnO2 composition exhibited maximum sensor response due to strong surface electric fields.
• Enhanced sensor response under low-intensity radiation (30% increase at 7.7 ppm NO2).
• Achieved a lower sensitivity limit of 0.2 ppm NO2 at room temperature.
• Demonstrated temporal stability of the sensors.

Conclusions:

• TiO2-SnO2 nanocomposites with n-n heterojunctions are effective for high-performance NO2 gas sensing.
• Surface electric fields at heterojunctions significantly influence gas sensitivity.
• The developed sensors show promise for practical applications due to their sensitivity, stability, and radiation-enhanced response.