Precise preparation of WO₃@SnO₂ core shell nanosheets for efficient NH₃ gas sensing

Area of Science:

• Materials Science
• Chemical Sensing
• Nanotechnology

Background:

• Developing high-performance ammonia (NH3) sensors is critical for environmental and living space monitoring.
• Ammonia gas detection requires sensitive and selective sensing materials.
• Micro-electro-mechanical system (MEMS) technology offers miniaturization potential for gas sensors.

Purpose of the Study:

• To engineer structurally well-defined WO3@SnO2 core-shell nanosheets for enhanced ammonia gas sensing.
• To investigate the effect of tunable SnO2 shell thickness on sensor performance.
• To elucidate the sensing mechanism behind the core-shell heterojunction structure.

Main Methods:

• Fabrication of WO3@SnO2 core-shell nanosheets using atomic layer deposition (ALD) to control SnO2 shell thickness.
• Integration of the nanosheets into a miniaturized gas sensor based on micro-electro-mechanical system (MEMS).
• Characterization of gas sensing properties, including response and selectivity, at various temperatures.

Main Results:

• WO3@SnO2 core-shell nanosheets with a 20-nm SnO2 shell exhibited the highest response (1.55) to 15 ppm NH3 at 200°C.
• The sensor demonstrated superior selectivity towards ammonia.
• The enhanced performance was attributed to the unique WO3-SnO2 core-shell heterojunction structure.

Conclusions:

• The developed WO3@SnO2 core-shell nanosheets offer a promising material for high-performance ammonia gas sensors.
• Atomic layer deposition provides precise control over shell thickness, enabling tunable sensing properties.
• The heterojunction-depletion model explains the enhanced sensing mechanism, paving the way for future sensor design.