Morphology, phase structure and acetone sensitive properties of copper-doped tungsten oxide sensors

Cu-doped WO3 hollow fibers were prepared by electrospinning technique, combined with the sol–gel method and reasonable sintering procedure. The morphology and crystal phase structure were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The gas-sensing properties were investigated as functions of the amount of Cu element, concentration of acetone and cooling method. The 3 mol% Cu-doped WO3 hollow fibers using quenching for cooling exhibit high response and good selectivity to acetone. The response of the hollow fibers to 20 ppm of acetone was 6.43, which could be attributed to their high surface-to-volume ratio and junction structure. Partial substitution of W6+ in WO3 with Cu2+ and quenching treatment could lead to a triclinic phase structure, which has a low symmetry, large dipole moment and strong interaction with acetone molecules and results in a good selectivity to acetone gas. Therefore, Cu-doped WO3-based materials show the potential application for semiconducting gas sensors in the diagnosis of diabetes.