PdO,Au, CdO修饰SnO2纳米纤维的制备及其气敏特性

采用静电纺丝的方法制备了SnO₂纳米纤维,并分别用PdO、Au、CdO对该纳米纤维材料进行表面修饰.用X射线衍射(XRD)、扫描电子显微镜(SEM)、X射线能谱(EDX)、X射线光电子能谱(XPS)分析、Brunauer-Emmett-Teller (BET)比表面积测试对材料进行表征.修饰前后, SnO₂纳米纤维都是由约15 nm的纳米颗粒构成的直径约为200 nm的多级结构材料.采用静态测试系统对纯SnO₂及不同物质修饰的SnO₂的气敏特性进行测试,结果表明,未修饰的SnO₂纳米纤维气敏元件对甲醛具有较好的响应.修饰后的SnO₂材料的气敏特性都有明显的改善. CdO修饰的SnO₂气敏元件对甲醛的响应值最高,且响应恢复时间短,选择性好. Au修饰的SnO₂气敏元件对甲醛响应的最佳工作温度从300 ℃降到了200 ℃.经PdO修饰后, SnO₂纳米纤维对甲苯的响应值变得最高.初步分析了经过修饰的SnO₂气敏材料的敏感机理.

Preparation and Gas Sensing Properties of PdO,Au, CdO Coatings on SnO2 Nanofibers

SnO₂ nanofibers fabricated by electrospinning were coated with PdO, Au, and CdO. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDX), X-ray photoelectron spectroscopy (XPS), and Brunauer-Emmett-Teller (BET) tests were used to characterize the nanofibers. The diameters of bare and coated SnO₂ nanofibers were approximately 200 nm, and had 15-nm diameter grains. The gas-sensing properties of all the nanofibers were characterized under static gas conditions. The results indicated that the bare SnO₂ nanofibers were sensitive to formaldehyde; however the sensitivity of the coated nanofibers was better. In particular, the CdO-coated SnO₂ exhibited the highest sensitivity to formaldehyde, the shortest response and recovery times, and good selectivity. The operating temperature of the Au-coated SnO₂ decreased from 300 to 200 ℃, while the PdO-coated SnO₂ exhibited the highest sensitivity to toluene. The sensing mechanism of the coated SnO₂ nanofibers was investigated.