ZnO掺杂的SnO_2纳米纤维的制备、表征及气敏机理(英文)

Preparation, Characterization and Gas Sensing Mechanism of ZnO-Doped SnO_2 Nanofibers

以二水氯化亚锡(SnCl2·2H2O)为盐原料,采用静电纺丝的方法制备了SnO2纳米纤维.为了研究ZnO掺杂对SnO2形貌、结构及化学成分的影响,分别制备了不同含量ZnO掺杂的SnO2/ZnO复合材料.利用热重-差热分析(TG-DTA)、X射线衍射(XRD)、傅里叶变换红外(FTIR)光谱仪、扫描电镜(SEM)及能量色散X射线(EDX)光谱对材料的结晶学特性及微结构进行了表征.制备的SnO2/ZnO复合材料是由纳米量级的小颗粒构成的分级结构材料.ZnO含量不同,对应的SnO2/ZnO复合材料结构不同.表征结果表明ZnO的掺杂量对SnO2材料的形貌及结构均起着重要作用.将制备的不同ZnO含量的SnO2/ZnO复合材料进行气敏测试,测试结果表明,Sn:Zn摩尔比为1:1制作的气敏元件对甲醇的灵敏度优于其它摩尔比的气敏元件.讨论了SnO2/ZnO复合材料气敏元件的敏感机理.同时针对Sn:Zn摩尔比为1:1时表现出最好的气敏响应,分析了其原因,包括Zn的替位式掺杂行为、ZnO的催化作用、过量ZnO对SnO2生长的抑制作用以及SnO2与ZnO晶粒界面处的异质结.

SnO2 nanofibers were fabricated by electrospinning, using SnCI2.2H20 as the raw material. The influences of ZnO doping on the morphologies, structures, and compositions of the SnO2 nanofibers were studied by introducing different amounts of ZnO into the SnO2. The crystallography and microstructures of the synthesized SnO2/ZnO composite nanofibers with different molar ratios of Sn to Zn were investigated using thermogravimetric/differential thermal analysis （TG-DTA）, X-ray diffraction （XRD）, Fourier-transform infrared （FTIR） spectroscopy, scanning electron microscopy （SEM）, and energy dispersive X-ray （EDX） spectroscopy. The obtained SnO2/ZnO composite nanofibers with different ZnO contents had hollow hierarchical structures composed of nanocrystals. Different amounts of ZnO gave different structures. The characterization results showed that the introduction of ZnO into SnO2 played an important role in the SnO2 nanofiber structure. The gas sensing properties of sensors based on different Z.nO-doped SnO2 nanofibers were tested. The results indicated that the methanol-sensing performance of the sensor containing SnO2/ZnO in a molar ratio of 1：1 was better than those of the others. The sensing mechanisms of ZnO-doped SnO2 nanofibers were examined in detail. Possible reasons for the enhanced response of the SnO2/ZnO-based sensor with a molar ratio of 1：1 are substitutional doping of Zn into Sn02, the catalytic effect of ZnO addition, and the inhibitory effect of excess ZnO, as well as the heterojunction across the Sn02 and ZnO interface.