High sensitivity ethanol sensor based on MoO3 nanoparticles and its sensing mechanism

MoO3 is an excellent and greatly concerned gas-sensitive material, especially for ethanol detection. In this study, MoO3 nanoparticles were prepared by thermal evaporation and mechanical grinding. The MoO3 nanoparticles were characterized by scanning electron microscopy(SEM), X-ray diffraction(XRD), Raman spectroscopy, Ultraviolet-visible (UV-Vis) absorption spectroscopy, X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR) spectra. Ethanol gas sensor based on MoO3 nanoparticles has the same optimum working temperature(180 degrees C) under the background of nitrogen and air, and the sensitivity is 350 and 71, respectively, when the ethanol concentration is 100 ppm. By comparing the sensitivity and current increase corresponding to the increase of ethanol concentration from 3 ppm to 5000 ppm, it is concluded that the gas-sensitive response of MoO3 to ethanol gas in the background of nitrogen and air is dominated by lattice oxygen and adsorbed oxygen ions, respectively, and the gas-sensitive performance based on lattice oxygen response is significantly better than that based on adsorbed oxygen ion response. This work is helpful to further study the gas sensing mechanism of MoO3 and similar metal oxides.