<i>In Situ</i> TEM Technique Revealing the Deactivation Mechanism of Bimetallic Pd–Ag Nanoparticles in Hydrogen Sensors
Xueqing Wang, Ming Li, Pengcheng Xu, Ying Chen, Haitao Yu, Xinxin Li
Abstract
Bimetallic Pd–Ag alloy nanoparticles exhibit satisfactory H2-sensing improvements and show application potential for H2 sensor construction. However, the long-term stability of the H2 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 °C and phase segregation at 500 °C. Guided by the failure mechanisms, the H2 sensor is comprehensively optimized based on the working temperature and the amount of Pd–Ag alloy nanoparticles. The optimized sensor exhibits satisfactory H2-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.