In Situ TEM Technique Revealing the Deactivation Mechanism of Bimetallic Pd-Ag Nanoparticles in Hydrogen Sensors

Bimetallic Pd-Ag alloy nanoparticles exhibit satisfactory H-2-sensing improvements and show application potential for H-2 sensor construction. However, the long-term stability of the H-2 sensor with Pd-Ag nanoparticles as the catalyst is found to dramatically decrease during operation. Herein, gas-cell in situ transmission electron microscopy (TEM) is used to investigate the failure mechanisms of Pd-Ag nanoparticles under operation conditions. Based on the in situ TEM results, the Pd-Ag nanoparticles have two failure mechanisms: particles coalescence at 300 degrees C and phase segregation at 500 degrees C. Guided by the failure mechanisms, the H-2 sensor is comprehensively optimized based on the working temperature and the amount of Pd-Ag alloy nanoparticles. The optimized sensor exhibits satisfactory H-2-sensing properties, and the response decline of the sensor after 1 month is negligible. The revealing of the failure mechanisms with in situ TEM technology provides a valuable route for developing gas sensors with high long-term stability.

Automated summary

Bimetallic Pd-Ag alloy nanoparticles have been found to enhance the performance of H-2 sensors. However, the long-term stability of the sensors with Pd-Ag nanoparticles as catalysts decreases significantly during operation. In this study, gas-cell in situ transmission electron microscopy (TEM) was used to investigate the failure mechanisms of Pd-Ag nanoparticles under operation conditions. Based on the results, two failure mechanisms were identified, and the H-2 sensor was comprehensively optimized to improve stability. The optimized sensor exhibited satisfactory H-2-sensing properties and negligible response decline after 1 month.