Failure Mechanism of Palladium-Silver Nanocatalysts-Sensitized Hydrogen Microsensor Revealed by In-Situ Transmission Electron Microscopy

Gas-cell in-situ transmission electron microscopy (TEM) is utilized to reveal the failure mechanism of MEMS H2 gas sensor with PdAg@ZnO nanowires as the sensing material. The morphology evolution of PdAg nanocatalyts is real-timely recorded to elucidate the mechanism for the degenerated sensing response of H2 sensors, which is a big challenge for the conventional ex-situ characterization methods. The in-situ TEM experimental results indicate that Ostwald ripening-induced coalescence of adjacent alloy nanoparticles in the working process brings the deactivation of bimetallic catalysts. According to the in-situ TEM results, the PdAg-based H2 sensor has been optimized and the optimized H2 sensor exhibits a satisfactory sensing performance and the detection limit is lower than 1 ppm.