异质复合结构纳米纤维SnO2/ZnO的制备及其气敏特性研究

Preparation and Gas Sensing Property of SnO_2/ZnO Composite Hetero-nanofibers Using Two-step Method

采用静电纺丝法制备了多级中空结构的SnO_2纳米纤维,然后将SnO_2纳米纤维置于90℃乙酸锌溶液中,恒温水浴条件下,在SnO_2纳米纤维上生长了ZnO纳米球,形成了异质结构的SnO_2/ZnO复合纳米纤维。分别通过XRD、SEM、EDX和XPS等表征手段对异质复合纳米纤维SnO_2/ZnO材料的结构、形貌及元素含量进行了表征分析。异质结构的SnO_2/ZnO复合纳米纤维保持了SnO_2纳米纤维多级中空的纤维结构,SnO_2纳米纤维长度约为300 nm,依附于SnO_2纤维表面的SnO_2纳米颗粒生长的ZnO纳米球直径为250~300 nm。采用静态气体测试系统对异质复合纳米纤维SnO_2/ZnO气敏元件的气敏性能进行了测试。测试结果表明:异质复合纳米纤维SnO_2/ZnO气敏元件在最佳工作温度350℃下,对(0.5~100)×10-6丙酮具有优异的响应灵敏度、较好的选择性和长期稳定性。异质复合纳米纤维SnO_2/ZnO中存在于ZnO纳米球与SnO_2纳米颗粒间的N-N同型异质结导致复合材料晶界势垒高度的降低,改善了电子与空穴的输运特性,促使SnO_2/ZnO异质复合纳米纤维的吸附能力大大增强,从而改善了SnO_2/ZnO元件的丙酮敏感特性。

A two-step route was used to prepare SnO2/ZnO composite hetero-nanofibers. In the first step, hierar- chical SnO2 nanofibers were synthesized by electrospinning; in the second step, ZnO nanospheres were fabricated in zinc acetate solution using water bath at 90℃. The morphology, structure and composition of SnO2/ZnO composite hetero-nanofibers were characterized and analyzed by XRD, SEM, EDX, and XPS. SnO2 nanofibers in the composite materials keep hollow and hierarchical structure with 300 nm in diameter. The diameters of ZnO nanospheres grown on SnO2 nanofibers are 250-300 nm. Gas sensing properties of SnO2/ZnO composite hetero-nanofibers Were tested using a static gas testing system. Gas sensing properties of pure SnO2 nanofibers and ZnO nanospheres were also studied to compare their gas sensing properties. The results show that SnO2/ZnO com- posite hetero-nanofiber gas sensors exhibit excellent sensing sensitivity, selectivity and long-tern stability for （0.5-100）×10-6 acetone at 350℃. N-N homotype heterojunctions, existed in the joint between ZnO nanospheres and SnO2 particles in the SnO2/ZnO composite materials, change the potential barrier height. The absorption capacity of SnO2/ZnO composite materials increases greatly due to changes of the transport characteristics of electrons and holes, which results in the improvement of acetone sensing properties of SnO2/ZnO composite materials.