超声喷雾热分解法制备ZnO基纳米薄膜及其特性研究

发布时间：2018-02-15 07:50

  本文关键词： ZnO 纳米棒 分等级结构 ZnO/SnO2 ZnO/ZnFe2O4 气体传感器　出处：《吉林大学》2015年硕士论文　论文类型：学位论文

【摘要】：在诸多的纳米材料中，，ZnO作为一种直接带隙宽禁带半导体材料，具有优异的电、光和磁等性能，被广泛地应用于各个领域，尤其是在光电器件和气体传感器领域。大量研究证明，器件的性能与材料的结构与微观形貌密切相关。所以，不同尺寸和形貌的ZnO纳米结构已经通过各种物理化学方法制备而成。一维（1D）的ZnO纳米结构具有高的比表面积、大的活性位点密度以及优异的物理化学特性，被认为是制作微观纳米级光电器件和气体传感器的优质材料。另一方面，由低维的ZnO纳米材料和其他氧化物组装而成的分层、多孔及空心结构的复合氧化物作为气体传感器的敏感层可以显著提高气敏性能。为了制备大面积的分等级结构纳米薄膜，本论文采用简单的超声喷雾热分解法，在玻璃衬底上原位合成出一维ZnO纳米棒，并以此为模板二次生长制备出分等级结构ZnO/SnO2、ZnO/ZnFe2O4纳米薄膜。具体研究内容如下： 1）采用简单的超声喷雾热分解法制备出一维ZnO纳米棒阵列，ZnO纳米棒的长度约为9μm。通过改变反应时间控制纳米棒的长度，由此获得了样品的形态演化趋势，进而给出了一种可能的ZnO纳米棒生长机制。另外，我们还测试了在室温下的光致发光谱，测试结果表明所制备的ZnO纳米棒阵列光致发光谱是由一个强紫外发射峰和一个宽的绿光发射峰组成。 2）通过两步超声喷雾热分解法制备了中空圆梳状ZnO/SnO2复合敏感材料，并构建了高性能乙醇气体传感器。ZnO/SnO2分等级纳米结构是由ZnO纳米棒和二次生长的纳米线组成。在纳米线生长过程中，ZnO纳米棒的内部变成中空结构。通过TEM表征发现，二次生长的纳米线是由ZnO和SnO2两种材料共同组成的。由内而外的奥斯特瓦尔德熟化机理可以解释这种空心纳米结构的形成。气敏特性结果显示，以所制备的ZnO/SnO2为敏感材料的传感器在275℃对100ppm的乙醇响应值达到10。 3）为了提升ZnO纳米棒阵列的气敏特性，我们通过简单的两步合成法构筑了分等级结ZnO/ZnFe2O4纳米森林，将制备的ZnO纳米棒浸渍在0.2M的FeSO4溶液中再经过烘干烧结后得到。气敏测试结果表明，与单一ZnO纳米棒阵列相比，分等级结构ZnO/ZnFe2O4对乙醇有更高的灵敏度和更快速的响应。 综上所述，本论文采用超声喷雾热分解法在石英衬底上制备出一维有序的ZnO纳米棒阵列。为了进一步提升ZnO纳米棒的气体传感特性，我们采用半导体复合技术对敏感材料进行了改性，制备出分等级结构ZnO/SnO2和ZnO/ZnFe2O4复合氧化物。复合后的材料对100ppm乙醇的灵敏度与单一材料相比，其灵敏度得到明显提升。异质结的势垒高度在不同气氛中的变化可能是复合氧化物传感性能提升的主要原因。
[Abstract]:As a direct bandgap wide bandgap semiconductor material, ZnO has been widely used in many fields, especially in the field of optoelectronic devices and gas sensors, due to its excellent electrical, optical and magnetic properties. The properties of the devices are closely related to the microstructure and morphology of the materials. Therefore, the ZnO nanostructures with different sizes and morphologies have been prepared by various physical and chemical methods. Large active site density and excellent physical and chemical properties are considered to be excellent materials for fabricating micro nanometer optoelectronic devices and gas sensors. On the other hand, lamination made of low dimensional ZnO nanomaterials and other oxides, The composite oxides with porous and hollow structures can improve the gas sensing performance significantly. In order to prepare large area graded nanofilms, a simple ultrasonic spray pyrolysis method is used in this paper. One-dimensional ZnO nanorods were synthesized on glass substrates in situ and used as templates to prepare graded ZnO / Sno _ 2 / ZnO / ZnFe _ 2O _ 4 nanocrystalline films. 1) the length of one-dimensional ZnO nanorods prepared by simple ultrasonic spray pyrolysis method is about 9 渭 m. By changing the reaction time to control the length of nanorods, the morphologic evolution trend of the samples is obtained. Furthermore, a possible growth mechanism of ZnO nanorods is given. In addition, we have also measured the photoluminescence spectra at room temperature. The results show that the photoluminescence spectra of the ZnO nanorods array are composed of a strong ultraviolet emission peak and a wide green emission peak. 2) Hollow circular comb ZnO/SnO2 composite sensitive materials were prepared by two-step ultrasonic spray pyrolysis. The high performance ethanol gas sensor. ZnO / Sno 2 nanostructure is composed of ZnO nanorods and secondary growth nanowires. During the growth of nanowires, the inner structure of ZnO nanorods becomes hollow. It is found by TEM characterization. The secondary growth nanowires are composed of two kinds of materials, ZnO and SnO2. The formation of this hollow nanostructure can be explained by Ostwald aging mechanism from inside to outside. The sensor with ZnO/SnO2 as the sensitive material has a response value of 10. 5% to 100 ppm ethanol at 275 鈩

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