Yb-In_2O_3纳米管的制备及其对甲醛的优异气敏性能

采用单管静电纺丝的方法成功制备了纯的与Yb掺杂的In_2O_3纳米管(Yb-In_2O_3).利用扫描电子显微镜和X射线衍射对样品的结构和形貌进行了表征,制作了基于纯In_2O_3和Yb-In_2O_3纳米管的气敏元件.研究表明,Yb-In_2O_3纳米管气敏元件在230℃下对100 ppm甲醛的灵敏度为69.8,是纯In_2O_3纳米管气敏元件对同浓度甲醛灵敏度(18.4)的3.8倍,其对100 ppm甲醛的响应恢复时间分别为4 s和84 s.并且,基于Yb-In_2O_3纳米管的气敏元件对100 ppb甲醛的灵敏度达到2.5.此外,该气敏元件还具有出色的选择性及稳定性,具备良好的实际应用前景.

Fabrication and excellent formaldehyde Gas sensing properties of Yb-doped In2O3 nanotubes

Pure and Yb-doped In₂O₃ nanotubes have been successfully fabricated by using the single-capillary electrospinning method, followed by calcination. The morphological and structural characteristics of the as-synthesized nanotubes are investigated by scanning electron microscope (SEM) and X-ray powder diffraction (XRD). The SEM images reveal that all the pure and Yb-doped In₂O₃ nanotubes are distributed evenly, and the average diameter of the as-synthesized nanotubes is about 200 nm. The XRD analysis results show that the as-prepared samples are well-crystallized, and the diffraction peaks can be indexed according to cubic In₂O₃. Gas sensors based on pure and Yb-doped In₂O₃ nanotubes have been fabricated and investigated for formaldehyde detection in detail. As shown in the experimental results, Yb-doped In₂O₃ nanotubes exhibit enhanced formaldehyde sensing properties compared with pure In₂O₃ nanotubes. At the optimum operating temperature of 230 ℃, the response of the gas sensors based on pure In₂O₃ nanotubes to 100 ppm formaldehyde is 18.4, while the response of gas sensors based on Yb-doped In₂O₃ nanotubes is 69.8 in the same working condition, which is 3.8 times larger than that of pure In₂O₃ nanotubes. The improvement of Yb-doped In₂O₃ nanotubes gas-sensing property may be due to the formation of the heterojunction structure at the interface between the two different semiconducting oxides. The response and recovery times of Yb-doped In₂O₃ nanotubes to 100 ppm formaldehyde are about 4 s and 84 s respectively, indicating the fast response speed of Yb-doped In₂O₃ nanotubes. Moreover, even at 100 ppb of formaldehyde a detectable response can be observed and the value is 2.5. The low limit of formaldehyde detection shows that the as-synthesized Yb-doped In₂O₃ nanotube gas sensors can be used for the detection of dilute formaldehyde. Furthermore, the Yb-doped In₂O₃ nanotube gas sensors have excellent selectivity towards formaldehyde. In this experiment, acetone has the highest sensitivity in a variety of common interfering gases and the response value is 22 to 100 ppm at 230 ℃, which is less than one-third of the sensitivity of formaldehyde. Carbon monoxide has the lowest response value of 1.7, which is much lower than that of formaldehyde. In addition, the responses of gas sensors to different concentrations of formaldehyde almost unchanged during the test (50 days), indicating that the Yb-doped In₂O₃ nanotubes possess good repeatability and long-term stability. The excellent formaldehyde gas-sensing properties of Yb-doped In₂O₃ nanotubes indicate that the as-synthesized nanomaterials can be used as a promising candidate to detect formaldehyde in practical applications.