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.