In situ growth of hierarchical In2O3 hollow spheres for ppb-level NO2 sensing at different low temperatures

The development of gas sensors with high sensitivity to NO2 at low operating temperatures is crucial for environmental monitoring. Herein, the In2O3 hollow spheres were successfully in situ grown on ceramic tubes via a facile hydrothermal process followed by calcination. Morphological characterization indicates that the hierarchical In2O3 hollow spheres are constructed by nanoparticles with diameters of similar to 25 nm. The fabricated In2O3 deposited film (In2O3-DF) sensor demonstrates outstanding NO2 sensing performance with high response value (448.1) to 10 ppm NO2 and low detection limit (30 ppb) at 92 degrees C. Meanwhile, it can achieve high sensitivity and rapid detection to ppm and ppb levels of NO2 at room temperature (RT). Such excellent gas-sensing property is attributed to the in situ growth of hierarchical and hollow structures, which provide more active sites for fast gas molecules diffusion and short pathways for charge transport when target gases diffuse onto the entire sensing layer.