Facile Synthesis and Acetone Sensing Performance of Hierarchical SnO₂ Hollow Microspheres with Controllable Size and Shell Thickness

A facile method to prepare SnO₂ hollow microspheres has been developed by using SiO₂ microspheres as template and Na₂SnO₃ as tin resource. The obtained SnO₂ hollow microspheres were characterized by X-ray diffraction, scanning electron microscopy, high resolution and transmission electron microscopy, and Brunauer–Emmett–Teller analysis, and their sensing performance was also investigated. It was found that the diameter of SnO₂ hollow microspheres can be easily controlled in the range of 200–700 nm, and the shell thickness can be tuned from 7.65 to 30.33 nm. The sensing tests showed that SnO₂ hollow microspheres not only have high sensing response and excellent selectivity to acetone, but also exhibit low operating temperature and rapid response and recovery due to the small crystal size and thin shell structure of the hollow microspheres, which facilitate the adsorption, diffusion, and reaction of gases on the surface of SnO₂ nanoparticles. Therefore, the SnO₂ hollow microsphere is a promising material for the preparation of high-performance gas sensors

Doping Metal Elements of WO₃ for Enhancement of NO₂‑Sensing Performance at Room Temperature

WO₃ nanoparticles doped with Sb, Cd, and Ce were synthesized by a chemical method to enhance the sensing performance of WO₃ for NO₂ at room temperature. The doping with Sb element can significantly enhance the NO₂-sensing properties of WO₃. Upon exposure to 10 ppm of NO₂, particularly the 2 wt % Sb-doped WO₃ sample exhibits a 6.8-times higher response and an improved selectivity at room temperature compared with those of undoped WO₃. The enhanced NO₂-sensing mechanism of WO₃ by doping is discussed in detail, which is mainly ascribed to the increase of oxygen vacancies in the doped WO₃ samples as confirmed by Raman, photoluminescence, and X-ray photoelectron spectroscopy spectra. In addition, the narrower band gap may also be responsible for the enhancement of response as observed from the corresponding ultraviolet–visible spectra