Synthesis, characterization and alcohol-sensing properties of rare earth doped In2O3 hollow spheres

In2O3:RE (RE = La, Er, Yb) hollow spheres were successfully prepared by using carbon sphere as template, and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The experimental results showed that the synthesized hollow spheres had a diameter of ca. 300 nm and the thickness of the shells was ca. 40 nm. The doping of rare earth improved the responses of In2O3 sensors to alcohol at the optimal operating temperatures, but had no obvious effect on the response/recovery times. Moreover, the In2O3:RE sensors exhibited good selectivity and stability. The possible reasons for the effect of rare earth doping on the alcohol-sensing properties were studied. The enhancements of the response may be attributed to high surface activity of the In2O3:RE, which resulted from the lattice defect and chemisorbed oxygen.