In Situ Exsolution Catalyst: An Innovative Approach to Develop Highly Selective and Sensitive Gas Sensors

Area of Science:

• Materials Science
• Chemical Engineering
• Sensor Technology

Background:

• Oxide semiconductor gas sensing performance is improved by noble metal or metal oxide catalysts.
• Uniform distribution and thermal stability of nanoscale catalysts are crucial for high-temperature operation.
• In situ exsolution offers a method for creating stable, well-distributed nanoparticles on sensing materials.

Purpose of the Study:

• To investigate the impact of cobalt (Co)-exsolved nanoparticles on the gas sensing properties of La0.43Ca0.37Co0.06Ti0.94O3- (LCCoT).
• To explore the relationship between reduction temperature, nanoparticle characteristics, and gas sensing performance.
• To demonstrate a novel approach for developing high-performance, thermally stable gas sensors.

Main Methods:

• Synthesis of LCCoT perovskite material.
• Application of an in situ exsolution process with varying reduction temperatures to form Co-exsolved nanoparticles.
• Gas sensing measurements of ethanol at elevated temperatures (350 °C).
• Characterization of nanoparticle size and distribution.
• Demonstration of catalytic effects using proton transfer reaction-quadrupole mass spectrometry.

Main Results:

• The amount and size of Co-exsolved nanoparticles were controlled by adjusting the reduction temperature.
• LCCoT sensors with Co-exsolved nanoparticles prepared at 700 °C showed a 10-fold increase in response to 5 ppm ethanol (response ratio of 116.3) at 350 °C compared to non-exsolved sensors.
• The enhanced gas response was attributed to the catalytic activity of uniformly distributed Co-exsolved nanoparticles and the formation of p-n junctions.
• The catalytic effect of Co-exsolved nanoparticles was confirmed via mass spectrometry.

Conclusions:

• In situ exsolution is an effective method for preparing uniformly distributed, thermally stable Co nanoparticles on LCCoT perovskites.
• Controlling the exsolution process allows for tuning nanoparticle characteristics and optimizing gas sensor performance.
• This approach provides a pathway for designing advanced, high-performance gas sensors with improved thermal stability for applications like ethanol detection.