A room temperature all-optical sensor based on two-dimensional SnS₂ for highly sensitive and reversible NO₂ sensing.

Area of Science:

• Materials Science
• Optical Engineering
• Environmental Monitoring

Background:

• Nitrogen dioxide (NO2) is a major toxic air pollutant.
• Existing NO2 sensors often require complex structures or external heaters.
• Nanoscale materials offer enhanced sensitivity but can increase complexity.

Purpose of the Study:

• To develop a room-temperature, all-optical NO2 sensor.
• To achieve high performance without non-optical peripherals.
• To leverage 2D materials for enhanced gas sensing.

Main Methods:

• Fabrication of a D-shaped optical fiber sensor coated with 2D tin disulfide (SnS2).
• Utilizing a 473 nm visible light source to excite SnS2 via evanescent field coupling.
• Monitoring changes in optical output power due to NO2-induced charge exchange with SnS2.

Main Results:

• Demonstrated an all-optical, room-temperature NO2 sensor.
• Achieved a significant optical power variation (up to 7 µW) at 50 ppb NO2.
• Reported an ultra-low limit of detection (LOD) of 0.464 ppb for NO2.
• Confirmed full reversibility of the sensor response.

Conclusions:

• The developed sensor offers a simple, feasible solution for high-performance NO2 detection.
• The all-optical approach eliminates the need for external non-optical peripherals.
• This technology is suitable for effective monitoring of hazardous gases.