Abstract:

The f-Ti₃C₂T _x /ZIF-8 composite material with heterostructures was synthesized by electrostatic self-assembly technology. The phase structure and microstructure of synthesized samples were characterized by FESEM, XRD, N₂ isothermal adsorption-desorption tests and their gas sensing properties estimated via a self-designed equipment with four test channels. The material analysis and testing showed that ZIF-8 material with regular shape was well-distributed on the surface and between layers of two-dimensional few-layered Ti₃C₂T _x, and there existed a typical heterostructure at the interfaces. The gas sensing performance tests indicated that the gas sensing response of the composite material toward 100μL/L NO₂ was as high as 98.35%, which was 2.1 times that of the ZIF-8 material. The heterostructures formed by the recombination of strongly conductive two-dimensional f-Ti₃C₂T _x and ZIF-8 not only provided conductive channels for the free electrons generated by the surface reaction of ZIF-8 and gas, but also strengthened the separation efficiency of electrons and holes during the gas-solid reaction on the surface of the composite material through the interface effect. Therefore, the gas sensing performances of the composite material toward NO₂ gas were significantly improved. Meanwhile, the layered structure of few-layered f-Ti₃C₂T _x /ZIF-8 composite material provided convenient diffusion paths for gas molecules to the surface of ZIF-8.

Key words: composite material, heterostructures, gas sensing performance, conductive channels, separation efficiency

摘要：

采用自组装法合成了具有异质界面的f-Ti₃C₂T _x /ZIF-8复合材料，采用场发射扫描电子显微镜、X射线衍射、N₂等温吸脱附测试对合成样品的物相结构和微观结构进行了表征，并通过自行设计的四通道气敏测试设备对其气敏性能进行了研究。材料分析测试发现，形状规则的ZIF-8材料均匀分布于二维少层Ti₃C₂T _x 的表面与层间，在界面处存在典型的异质结构。气敏性能测试表明：在225℃下，该复合材料对100μL/L NO₂的气敏响应高达98.35%，且是ZIF-8材料气敏响应的2.1倍。认为强导电的f-Ti₃C₂T _x 与ZIF-8复合后形成的异质结构，不仅为ZIF-8与气体表面反应产生的自由电子提供导电通道，而且通过界面效应强化了复合材料表面气固反应时电子与空穴的分离效率，进而显著提升了复合材料对NO₂气体的气敏性能。同时，f-Ti₃C₂T _x / ZIF-8复合材料的层状结构可以为目标气体分子向ZIF-8的扩散提供方便路径。

关键词: 复合材料, 异质结构, 气敏性能, 导电通道, 分离效率