摘要
纳米材料因其具有体相材料所不具备的新奇的物理与化学性质引起了人们广泛的关注和研究。而其中纳米金属氧化物材料更是因其特殊的理化性能成为了广泛使用的功能材料,如在微电子器件、催化剂、能量储存与转化等众多领域有着非常广泛的应用。氧化锌(ZnO)和氧化锡(SnO2)都是典型的n型宽禁带半导体氧化物,其室温禁带宽度分别为3.37 eV和3.65 eV。纳米氧化锌和氧化锡具有优异的光电性能以及高灵敏的气敏特性,一直被认为是金属氧化物中最有应用前景的两种功能材料,近年来,科研人员对各种形貌与结构的ZnO和SnO2纳米材料的合成、表征以及它们在纳米器件领域中的应用进行了深入研究。鉴于它们在未来功能器件中的重要性,本人在硕士期间也对ZnO和SnO2这两种金属氧化物的各种结构及性能进行了研究。
本论文利用水热法成功合成了ZnO纳米棒、ZnO纳米花及SnO2纳米空心球。并且利用扫描电镜(SEM)、X射线衍射仪(XRD)分析了ZnO纳米棒、ZnO纳米花的结构形貌,分析了ZnO纳米棒阵列的生长机理,利用扫描近场光学显微镜采用波长为448nm的氩离子激光器为激发源在室温下对ZnO纳米棒阵列进行了Raman光谱测试,纳米棒阵列室温下的拉曼光谱表现出纯的ZnO的拉曼特征峰,对牡丹花状ZnO纳米花和莲花状ZnO纳米花进行了光致发光(PL)测试,比较发光谱得知牡丹花状ZnO纳米花中的缺陷密度低于莲花状ZnO纳米花。重点对SnO2空心纳米球进行EDS、XRD、SEM、TEM等表征,并且将已制备好的SnO2空心球均匀分散到酒精中,然后涂在陶瓷管上的两个金电极之间做成一个简单的气敏元件,将其接入工作回路进行了气敏性研究,研究结果发现用这种SnO2纳米空心球制成的传感器具有更高的灵敏度和更快的响应和恢复时间。
Nano-materials have attracted much attention due to their novel physical and chemical properties which are different from their corresponding bulk materials and have potential technology applications in the fields of microelectronic devices, chemical and biological sensors, light-emitting, displays, catalysis, and energy conversion and storage devices as reported in literatures. ZnO and SnO2 with the large band gap of 3.37 eV and 3.65 eV, respectively, and highly achievable carrier concentration are suitable for application as the gas sensors, transparent electrodes, and other optoelectronic devices. Recently, much effort has been dedicated to the morphology-controllable synthesis of ZnO, SnO2 nanostructures and prototype nanodevices design and demonstration in some areas.
In this work, the study is mainly focused on the synthesis and characterization of ZnO and SnO2 nanostructures and gas sensing applications. A hydrothermal method has been developed for the preparation of the ZnO nanorods nanoarrays, nanoflowes and nanosheets, SnO2 hollow spheres. The morphologies, structure and compositions of the nanostructures have been characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), photoluminescence (PL) and transmission electron microscopy (TEM) techniques. Based on the measured PL spectra of the ZnO nanostructures with the peony-like and lotus flower-like morphologies the density of defects in these nanostructures has been studied. A simple gas sensor was fabricated by dispersing the as-prepared SnO2 hollow spheres between two gold electrodes on a ceramic tube in order to investigate the gas sensors properties of the SnO2 nanostructures in detail. The results showed that the gas sensor of the SnO2 hollow spheres exhibited good sensitivity to ethanol, as well as good responsibility, low detection limit and short response/recovery times.
引文
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