A dual ammonia-responsive sponge sensor: preparation, transition mechanism and sensitivity

Area of Science:

• Materials Science
• Chemical Sensing
• Nanotechnology

Background:

• Ammonia (NH3) is a crucial chemical with widespread industrial applications.
• Developing sensitive, real-time ammonia sensors is vital for environmental monitoring and safety.
• Existing ammonia sensors often require elevated temperatures or lack visual indicators.

Purpose of the Study:

• To develop a novel room-temperature ammonia sensor.
• To investigate the ammonia-responsive properties of a functionalized sponge material.
• To establish a visual and quantitative method for ammonia detection.

Main Methods:

• Fabrication of a polydimethylsiloxane-polyurethane (PDMS-PU) sponge decorated with indium hydroxide (In(OH)3) and bromocresol purple (BCP) nanoparticles.
• Characterization of the sponge's structural, wettability, and optical properties.
• Exposure of the functionalized sponge to varying ammonia concentrations and monitoring changes in wettability (water contact angle), color (macroscopic observation), and absorption spectra (UV-vis spectrometry).
• Assessment of the sensor's reproducibility and recovery performance upon heating.

Main Results:

• The In(OH)3-BCP-TiO2-based ammonia-responsive (IBT-AR) sponge exhibited superhydrophobic and yellowish properties in ambient air.
• Upon exposure to ammonia, the sponge transformed into a purple, superhydrophilic material, indicating a reversible color and wettability change.
• Real-time detection of ammonia was achieved with minimum detectable concentrations of 0.5% (wettability), 1.4 ppm (color), and 50 ppb (absorption signal).
• The sponge demonstrated excellent reproducibility and could recover its original state after thermal treatment.

Conclusions:

• The developed IBT-AR sponge functions as a highly sensitive and reproducible room-temperature ammonia sensor.
• The smart wettability and color-changing characteristics offer a promising platform for visual and quantitative ammonia detection.
• This functionalized sponge represents a significant advancement in the development of novel ammonia detectors for environmental and safety applications.