Effect of gamma irradiation on structural, electrical and gas sensing properties of tungsten oxide nanoparticles

Tungsten trioxide nanoparticles (WO3 NPs) find a wide variety of use in industrial applications, and particularly they possess good gas sensing capabilities. In this paper, WO3 NPs have been prepared by a microwave method and successively irradiated with 60Co gamma rays at different doses (0, 50 and 100 kGy). The effect of gamma irradiation on structural, electrical and gas sensing properties of irradiated WO3 nanoparticles (NPs) were investigated. The morphological and microstructural characteristics were studied using transmission electron microscopy (TEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR), respectively. The results of characterization have shown that γ-irradiation induces significant changes in the WO3 microstructure, favoring the tetragonal to triclinic transformation, along with a reduction of the grain size. Resistive sensors fabricated using γ-irradiated WO3 NPs were tested for detection of NH3, CO and CO2 in air. It was found that the response to NH3 decreased after γ-irradiation, while that of CO2 increased. Further, γ-irradiated WO3 based sensor exhibited improved recovery time for NH3, when compared to that of pristine WO3 based sensor. The behavior observed suggests that the acid-base characteristics of WO3 NPs sensing layer were also largely modified as a results of the surface microstructure changes after the γ-irradiation treatment. Results demonstrated that the γ-irradiation process could be an effective tool for tailoring the sensing properties of WO3 NPs. © 2016 Elsevier B.V.