Room Temperature NO2 Sensing Performance of Ag Nanoparticles Modified VO2 Nanorods

Ag-modified VO2 nanorods were prepared by a two-step method to improve the NO2 sensing performance at room temperature (25 degrees C). VO2 nanorods were synthesized by hydrothermal method, and Ag nano -particles were decorated on the surface of VO2 nanorods by annealing. The effects of annealing temperature on the microstructure and room temperature NO2 sensing properties were studied. The morphology and crystal structure of the samples were characterized by field emission scanning electron microscope and X-ray diffraction. The results showed that Ag nanoparticles with a diameter of about 45 nm were tightly decorated on the surface of VO2 nanorods when the annealing temperature was 450 degrees C. The room tem-perature gas sensing measurement of sensor to NO2 with concentration spanned from 1 to 5 ppm was carried out. The gas sensing test results showed that the sample annealed at 450 degrees C had the maximum sensitivity, and the response value was up to 2.54-5 ppm NO2. The response value gradually decreases as the relative humidity increases. The sensor also showed good selectivity and reproducibility for detection of NO2 gas. The good sensing performance could be attributed to the catalytic effect of Ag nanoparticles and the changing of the energy band gap. At the same time, the mechanism of Ag-modified VO2 nanorods to NO2 gas response is further discussed. These results are significant to prompt the applications of VO2 in room temperature NO2 gas detection. (c) 2021 Elsevier B.V. All rights reserved.