Confined rare earth cerium dioxide nanoparticles film for gas sensing: Experimental and theoretical studies

Nanostructured materials with small particle sizes have been widely used in resistive gas sensors due to their high specific surface area and surface activity. However, phenomena including agglomeration, growth and structural damage of nanostructures are almost inevitable during the processes of device fabrication or sensing tests, which makes it difficult to exert their expected activity. To address this issue, rare earth metal oxide CeO₂ was chosen as the model material to explore confined nanostructures in resistive gas sensors. The experiment successfully achieves the preparation of confined CeO₂ nanoparticles film using a pulsed laser deposition combined with rapid annealing technology. It is found that the confined CeO₂ nanoparticles film enables the efficient detection of volatile organic compound triethylamine, demonstrating a significant response of 20 (R_a/R_g) towards 100 ppm triethylamine, a fast response of 2 s, excellent stability and selectivity. By in-situ confinement in porous carbon matrix, dispersion and fixation of CeO₂ nanoparticles can be achieved, thereby fully utilizing their high surface activity. In addition, the porous carbon matrix can serve as a transport pathway for the target gas molecules and electrons, enabling efficient gas–solid reactions and effective collection of gas sensing signals. More importantly, the confined CeO₂ nanoparticles film was grown in-situ on commercial alumina flats gas sensing substrate, which can be directly used as sensing layer for gas sensors. Based on first-principles calculations, the triethylamine sensing mechanism of the confined CeO₂ nanoparticles film was systematically analyzed at the atomic and electronic scale. This study offers new insights into enhancing the gas sensing performance of resistive gas sensors through confined nanostructures design.