Efficient NH₃ Detection Based on MOS Sensors Coupled with Catalytic Conversion

Area of Science:

• Materials Science
• Chemical Engineering
• Sensor Technology

Background:

• Metal-oxide-semiconductor (MOS) gas sensors exhibit high sensitivity to nitrogen dioxide (NO2) but low response and poor selectivity to ammonia (NH3).
• Cross-sensitivity to interfering gases like carbon monoxide (CO) and ethanol complicates accurate NH3 detection with conventional MOS sensors.

Purpose of the Study:

• To develop a sensitive and selective NH3 detection method using MOS gas detectors.
• To improve the performance of MOS sensors for NH3 by employing a catalytic conversion strategy.

Main Methods:

• Preparation of platinum-supported catalysts (Pt-loaded HZSM-5 and Al2O3) via wet impregnation.
• Fabrication of MOS gas detectors using nanosized indium oxide (In2O3) and tungsten oxide (WO3) via screen-printing.
• Catalytic conversion of NH3 into NO2 for enhanced detection by MOS sensors.

Main Results:

• The proposed method enabled MOS sensors to detect NH3 with high sensitivity down to 0.25 ppm.
• The catalytic conversion significantly improved NH3 selectivity by combusting interfering reducing gases into CO2 and water.
• MOS sensors based on In2O3 and WO3 showed enhanced response to NH3 after catalytic conversion.

Conclusions:

• The catalytic conversion approach offers a promising solution for sensitive and selective NH3 detection using MOS gas sensors.
• This concept has potential for broader gas sensing applications by adapting catalysts and detectors.
• The study highlights the utility of integrating catalysis with MOS sensor technology for improved gas analysis.