奈米粒子的優點在於它擁有高表面積，因此廣泛用在醫藥、材料工程、環境..等領域。氧化鋅則是擁有寬能隙、高激子结合能以及高穩定性，因此，能應用於觸媒、太陽能、或是抗菌材料。
由於生成奈米氧化鋅有許多參數會影響它的結晶化，Part A是探討在不同前驅物所含的濃度與比例、保護劑添加的效應以及不同溶劑對於氧化鋅結晶過程的影響。用不同前驅物比例(鋅離子:氫氧根離子)合成氧化鋅，會發現在莫耳比為1:1、1:2、1:4時，分別形成奈米球、奈米雙錐以及花狀結構。在增加前驅物濃度時，會發現晶體成長為較大顆氧化鋅。而高濃度的保護劑，則會抑制奈米氧化鋅的成長。當溶劑由水換成乙二醇的時候，會則到此實驗中最小的奈米氧化鋅。將上述以合成的奈米粒子進行X-射線繞射和同步螢光光譜分析，得出此粒子擁有3.2-3.4 eV能隙以及六方纖鋅礦結構，因此可以判定此粒子微奈米氧化鋅。
甲醛是個環境汙染物，以及對人體有致癌的風險。光觸媒-奈米氧化鋅經過光降解程序，可以將甲醛降解為水和二氧化碳。因此Part A所合成的奈米二氧化鋅，選擇其中四種不同的形狀大小的奈米粒子進行光降解反應(Part B)。其中奈米氧化鋅的顆粒大小依序為6到25奈米(8號樣本)、100到600奈米(1號樣本和4號樣本)和大於1000奈米(2號樣本)的粒子，其中1號樣本和4號樣本可以比較相似大小但不同形狀(奈米球和花狀結構)，對於光降解的影響。根據Hantzsch 反應可偵測乙二醇的濃度，此反應將乙二醇進行環化反應形成黃色之3,5-diacetyl-1,4-dihydrolutidine化合物。使用可見光紫外光分光光譜儀波長在412奈米時，可得到乙二醇濃度與3,5-diacetyl-1,4-dihydrolutidine吸收值的關係式，此關係式與比爾-朗伯定律相符合。使用奈米氧化鋅進行光降解發現小顆粒的奈米粒子擁有最高的光降解效率，反之小顆粒的奈米粒子光降解效率最差，這是由於越小的奈米粒子，比表面積越大(使用比表面積與孔隙分佈分析儀)。而在相似大小時花狀結構擁有較高的比表面積，因此比奈米球來的有效，使用比表面積與孔隙分佈分析儀也可與此結果得證。

Nanoparticles have wide applications on medicine, material engineering, and environment, since they have high specific surface area. Zinc oxide has wide ban gap, large exciton binding energy, and mechanical stability, and therefore it has wide variety of potential applications in catalysts, solar cells and antibacterials. However, the characteristics of Zinc oxide strongly depends on its structure like shape and size.
Since the structure of zinc oxide nanoparticles is affected by difference parameters on crystallization process, the effects of precursor, protector , and solvent on the fabrication of zinc oxide nanoparticles are investigated in Part A of this thesis: Nanoparticles of zinc oxide were prepared at different precursor (zinc ion and hydroxide ion) concentrations and different precursor ratios. The observation on TEM indicated that with different ratios (1:1, 1:2 and 1:4) of zinc ion and hydroxide ion, the morphology of particles changed from nano-sphere, nano-bicone to flower-like structure. Particle size of zinc oxide was proportional to precursor concentration. High concentration of protector effectively regulated particle growth. The sizes of particles synthesized in ethylene glycol were smallest among all particles in this experiment. The energy band gap of these particles was 3.3 eV to be zinc oxide particle, and crystal structure by XRD indicated a wurtzite hexagonal lattice of zinc oxide.
Formaldehyde is one of pollutants and carcinogen, which can be degradated on photo-catalyst. Among zinc oxide nanoparticles with different sizes and shapes synthesized in Part A, three kinds of particle size (>micrometer, 100-600 nm, and 6-25 nm) and two kinds of particle shape (flower-like shape and nano-sphere) were chosen as photo-catalysts on oxidation of formaldehyde in Part B. The detection of formaldehyde is based on the Hantzsch reaction. This reaction involves the cyclization of 2,4-pentanedione and the formation of 3,5-diacetyl-1,4-dihydrolutidine (DDL), which can be detected by UV-vis absorption spectra. The relationship between absorbance of DDL at 412 nm and concentration of formaldehyde were determined on calibration curve, which was followed Beer–Lambert law. On oxidation, small particles had good efficacy on degradation and flower-like shape had higher efficacy than nano-sphere with similar size.

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