Glucose-mediated hydrothermal synthesis and gas sensing characteristics of WO3 hollow microspheres

Tungsten-coated carbon microspheres were prepared by one-pot hydrothermal reaction of an aqueous solution containing glucose and sodium tungstate. The spheres were converted into WO3 hollow microspheres by the decomposition of their core carbon. The [glucose]/[sodium tungstate] ratio of the stock solution determined not only the morphology of the precursors but also the phase of the powders after calcination. The WO3 hollow microspheres showed a higher gas response and more selective detection of 0.5–2.5 ppm NO2 than WO3 solid and nano-porous microspheres did. The enhanced NO2 sensing characteristics are explained in relation to the surface area, pore volume, and hollow morphology.