In-situ growth of mesoporous In2O3 nanorod arrays on a porous ceramic substrate for ppb-level NO2 detection at room temperature

Abstract Mesoporous In2O3 nanorod arrays were synthesized directly on a porous ceramic substrate via a one-step hydrothermal method. The morphology and structure of the obtained In2O3 nanorod arrays were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. The results revealed that In2O3 nanorod arrays with cubic phase were densely distributed on the porous ceramic substrate, showing the diameter of 120–200 nm and length of 0.5–1 μm. Especially, the nanorod was assembled by aggregated In2O3 nanoparticles with the diameters of 10–30 nm, and its large specific surface ensured the highly gas sensing performance for ppb-level NO2 detection. The response value of the mesoporous In2O3 nanorod arrays to 800 ppb NO2 was 14.9 at room temperature of 25 °C with a short response time of 14 s, and the ultraviolet light was loaded in the recovery process to shorten the recovery time to about 32 s. The growth and gas sensing mechanisms of the mesoporous In2O3 nanorod arrays were discussed. It demonstrates that this work provides a low-cost route for the fabrication of room-temperature NO2 gas sensor with high performance through in-situ growth of the sensing materials on a porous ceramic substrate.