Hydrothermal synthesis of Hydrangea macrophylla-like Ce-doped SnO₂ microspheres and their enhanced sensing properties

The hydrangea macrophylla-like SnO₂ microspheres doped with different Ce contents (0, 2, 6 and 10 mol%) were synthesized by a facile hydrothermal method. The crystal phase, micro morphology and element composites were investigated by x-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) with energy-dispersive spectroscopy (EDS) and x-ray photoelectric spectroscopy (XPS). The results demonstrated the hydrangea macrophylla-like microstructure of the prepared samples and the existence of Ce³⁺/Ce⁴⁺ when doped with Ce element. Furthermore, the synthesized Ce-doped SnO₂ samples' sensing properties were investigated. The SnO₂ microspheres doped with 6 mol% showed the largest response to acetone during 0.2–20 ppm at 320 °C as well as good selectivity and reproducibility. As discussed, the Ce doping that generates n-n type heterojunction and the Ce³⁺/Ce⁴⁺ conversion increases the resistance change of Ce-doped SnO₂ in reducing atmosphere and enhances the response. (paper)