水热合成一维α-MoO_3纳米棒及其湿敏性能研究

Hydrothermal Synthesis of 1-Dα-MoO_3 Nanorods and Their Humidity Sensing Properties

采用水热法,以钼酸铵和硝酸为原料合成了一维纳米α-MoO_3棒状材料,并利用X射线衍射(XRD)、扫描电镜(SEM)和透射电镜(TEM)对其物相及形貌进行了表征。一维α-MoO_3纳米棒直径为200~300nm,长度为5~10μm。一维α-MoO_3纳米棒表现出良好的湿敏性能,所制得的传感器在100Hz、11%~95%湿度范围内,其复阻抗-相对湿度关系在半对数坐标下有5个数量级的变化,线性度好。元件的恢复和响应时间较短,分别为3s和35s,元件的湿滞约为4%RH。利用器件在不同湿度下的阻抗图谱建立了相应的等效电路,分析其电导过程。结果表明,在低湿度范围内,器件传导主要依靠一维α-MoO_3材料内少量的自由电子传导以及材料本身束缚电荷的极化;在高湿度范围内,吸附水分子的分解和极化所引起的离子导电占主导地位。

1-D α-MoOa nanorods were synthesized under hydrothermal conditions by using （NH4）6 MoTO24· 4H2O and HNO3 as raw materials. X-ray diffraction （XRD）, scanning electron microscope （SEM） and transmission electron microscope （TEM） were used to characterize phase and morphology of the samples. The width of the a-MoO3 nanorod was about 2O0-300 nm, and the length was about 5--10 μm. 1-D a-MoO3 nanorods showed good humility sensing properties. The curve of impedance vs. relative humility （RH） changed near five orders of magnitude with good linearity, when RH varied from 11% to 95% at 100 Hz. The response and recovery time of the sensor were about 3 s and 35 s, respectively. The maximum hysteresis was only 4% RH at 100 Hz. In order to explain the conduction process of the sensor, corresponding equivalent circuits were established by complex impedance plots of the device at various humidity ranges. In low RH range, the conduction process was dominated mainly by conduction （charge carriers） and polarization （bounded electrons） of the grains of 1-D α-MoOa nanorods, while in high RH range, by decomposition and polarization of the absorbed water.