Highly Permeable CeO 2 Porous Hollow Microspheres with Multilevel Gas Channels for Rapid NH 3 Gas Response and Recovery Performance

Fast response and recovery performance is highly significant for real‐time monitoring of NH 3 gas due to the toxic and harmful feature. However, the commercialization of NH 3 gas sensors is still hindered by the limited gas transport channels and sluggish gas–solid kinetics. Herein, a series of highly permeable CeO 2 porous hollow microspheres with multilevel gas channels and tunable pore size is developed by modulating the anhydrous citric acid and hydrothermal times of the hydrothermal reaction. The sensor based on CeO 2 ‐2 hollow microsphere exhibits fast response speed (15 s) and recovery speed (20 s), high response value (16) to 100 ppm NH 3 at 200 °C. The unique permeable porous hollow structures as gas transport channels and vast active sites promote the gas–solid kinetics. In addition, a new NH 3 reaction process is revealed via in situ diffuse reflectance infrared transform spectroscopy. The gas sensing mechanism is uncovered by density functional theory calculations.