HKUST-1形貌对QCM甲苯传感器敏感性能的影响

Effect of morphology and grain size on toluene vapor sensing properties of HKUST-1 based QCM gas sensor

以室温超声法合成了不同形貌的金属有机框架化合物Cu 3(BTC)2(HKUST-1)的纳米颗粒,并将其制作成石英晶体微天平(Quartz Crystal Microbalance,QCM)构建甲苯传感器.利用扫描电子显微镜,透射电子显微镜,X射线衍射仪,全自动比表面积和孔隙度分析仪,傅里叶变换红外光谱仪等对HKUST-1的形貌和结构进行了表征,测试了不同形貌和比表面积的敏感材料对甲苯的传感性能.结果证明不同晶粒尺寸和暴露晶面的HKUST-1对甲苯的敏感性能有明显影响.当形貌从低能晶面的八面体逐渐转变为高能晶面的立方体时,晶体尺寸变小,孔径逐渐增大.在空间位阻效应和吸附热效应的协同作用下,HKUST-1对甲苯气体显示出特异性吸附和敏感性能,其中高能晶面暴露最多的立方体形貌的HKUST-1对体积分数为60×10^-6甲苯气体的响应值比八面体样品高出1倍.

Four HKUST-1 samples with different exposed crystal faces were synthesized by ultrasonic method at room temperature and were subsequently fabricated to QCM(Quartz Crystal Microbalance)sensor of toluene.Scanning electron microscope(SEM),transmission electron microscope(TEM),X-ray diffraction(XRD),Fourier Transform infrared spectroscopy and automatic specific surface and porosity analyzer were employed to characterize samples’morphologies,composition and porous distribution.The results show that the grain size and exposed crystal face together make a significant influence to the gas sensing properties of HKUST-1 to toluene.When the morphology changes from octahedron with high-energy crystal faces to cube with low-energy crystal faces,the crystal size decreases while the aperture increases.Under the synergistic effect of steric hindrance effect and adsorption heat effect,HKUST-1 exhibits specific adsorption and sensitivity to toluene molecules.The response value of the cubic shape of the HKUST-1 with the most exposed high energy crystal faces to 60×10^-6 toluene vapor is twice as high as that of the octahedron sample.