Fast response paper based visual color change gas sensor for efficient ammonia detection at room temperature

Area of Science:

• Materials Science
• Chemical Sensing
• Environmental Monitoring

Background:

• Ammonia (NH3) is a toxic gas requiring sensitive detection methods.
• Current ammonia sensors can be expensive, complex, or require external equipment.
• Development of low-cost, portable, and visual detection systems is needed.

Purpose of the Study:

• To develop a rapid, disposable paper sensor for detecting ammonia gas.
• To utilize perovskite halide (CH3NH3PbI3, MAPI) for visual ammonia sensing.
• To investigate the sensor's performance and detection mechanism.

Main Methods:

• Fabrication of a paper-based sensor using MAPI.
• Exposure of the sensor to varying concentrations of ammonia gas.
• Visual observation of color change (black to yellow) for detection.
• Gas chromatography-mass spectrometry (GC-MS) and other analytical techniques to confirm the mechanism.

Main Results:

• The MAPI paper sensor visually detects ammonia gas by changing color from black to yellow.
• Detection limits down to 10 ppm with a response time of ~10 seconds.
• Sensor is insensitive to moisture (up to 90% RH) and other gases (CH4, N2O, CO2).
• Mechanism involves MAPI conversion to PbI2 upon ammonia exposure, confirmed by XRD, EDX, UV-Vis, and PL.

Conclusions:

• A cost-effective, disposable, and visual paper sensor for ammonia detection has been successfully developed.
• The sensor demonstrates high sensitivity, rapid response, and good selectivity.
• This technology offers a promising solution for on-site, real-time ammonia monitoring.