Highly Sensitive Carbon Monoxide Sensor Element with Wide-Range Humidity Resistance by Loading Pd Nanoparticles on...

Area of Science:

• Materials Science
• Nanotechnology
• Chemical Sensing

Background:

• Developing highly sensitive carbon monoxide (CO) sensors with robust humidity resistance is crucial for environmental and safety monitoring.
• Tin dioxide (SnO2) nanoparticles are promising semiconductor materials for gas sensing applications.
• Palladium (Pd) loading is known to enhance the performance of SnO2-based gas sensors.

Purpose of the Study:

• To investigate the effect of different palladium (Pd) loading methods on SnO2 nanoparticles for CO sensing.
• To optimize the sensing layer thickness for improved CO sensor performance and humidity resistance.
• To develop a highly sensitive and humidity-resistant semiconductor-type CO gas sensor.

Main Methods:

• Synthesized Pd-loaded SnO2 nanoparticles using surface immobilization (SI) and colloidal protection (CP) methods.
• Characterized Pd nanoparticles on SnO2 using X-ray Photoelectron Spectroscopy (XPS).
• Evaluated sensor performance, including CO response and humidity resistance, at various temperatures (250-350 °C).

Main Results:

• XPS analysis confirmed Pd nanoparticles existed as a composite of PdO and Pd, irrespective of the loading method.
• CP-Pd/SnO2 demonstrated superior CO response in humid conditions and better resistance to humidity changes compared to SI-Pd/SnO2.
• A thinner sensing layer fabricated using the CP method further enhanced sensor response and humidity stability at 300 °C.

Conclusions:

• The colloidal protection (CP) method for Pd loading on SnO2 nanoparticles offers significant advantages for CO sensing.
• Optimizing Pd surface properties (size, dispersity, oxidation state) and sensing layer thickness is key to achieving high-performance CO sensors.
• The developed Pd/SnO2 sensor exhibits excellent sensitivity and wide-range humidity resistance.