Enhanced toluene sensing performance of gold-functionalized WO3·H2O nanosheets

Au nanoparticle-functionalized composites have been proven to be promising materials for gas sensing applications. We successfully synthesized tungsten oxide (WO3·H2O) nanosheets by a facile and effective hydrothermal process and decorated Au nanoparticles on their surface for ultra-high sensitivity levels to toluene gas. The structure and morphology of the samples were characterized by X-ray diffraction (XRD), Energy Dispersive X-ray Spectrometer (EDX), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Gas-sensing measurements revealed superior toluene sensing properties of Au nanoparticle-functionalized WO3·H2O nanosheets (Au-WO3·H2O) compared with bare WO3·H2O. The maximum response value of Au-WO3 reached 50-100 ppm toluene at 300 °C, which was nearly four times as high as that of bare WO3. Meanwhile, Au-WO3·H2O exhibited the shorter response/recovery time, better selectivity and lower operating temperature to toluene gas than those of bare WO3·H2O. Also, the mechanism involved in improving the toluene sensing properties of WO3·H2O by Au nanoparticle-functionalization was discussed.