- 學位論文
金屬奈米複合物的合成 與其在光催化與抗菌上的應用
Synthesis of Metal Nanocomposites and Their Photocatalytic and Antibacterial Properties.
摘要
本研究利用兩種方法來製備金屬奈米粒子複合物，一種是利用雷射誘導方式，另一種則是生物合成法，這兩種的製備方法過程中都不需使用到有機溶劑，所用到的試劑及材料也都相當環保，製備方式也相對地簡單、便利。因此，製備出兩種響應綠色化學環保議題的金屬奈米複合物，其一採用回收之農業廢棄物-香蕉偽莖嫩芯萃取液經測定後其總酚含量2.7 mg/g ( gallic acid equivalent / dry weight )，並由FT-IR鑑定出萃取液由多酚類化合物上的羥基可將銀離子包覆在內，可作為穩定分散劑與還原劑，透過CV得知可藉由氧化還原反應與硝酸銀反應合成銀奈米粒子，經由UV-Visible吸收光譜在銀奈米複合物之表面電漿共振特定吸收峰420nm初步鑑定銀奈米複合物之合成，且液體顏色由淺黃色呈現為深棕色。由穿透式電子顯微鏡，可觀察並計算出銀奈米複合物平均粒徑大約為10nm，並以EDS(能量色散X-射線光譜)確定各點含有銀，證明金屬奈米複合物之確實形成。最後，以XRD定性金屬奈米複合物之晶型結構為面心立方體。其二，則為使用ND：YAG脈衝雷射誘導製備出金-石墨烯奈米複合物及金-氧化石墨烯奈米複合物，並以UV-Visible吸收光譜，金-石墨烯在520nm之表面電漿共振特定吸收峰，確認其金屬奈米複合物的生成，而由外觀上可觀察出由淺灰色轉變為紅紫色液體。再由穿透式電子顯微鏡，可觀察及計算出為金-石墨烯及金-氧化石墨烯奈米複合物之平均粒徑，依條件參數的不同，約略2nm~33nm左右，並以EDS(能量色散X-射線光譜)確定各點中含金，再度證實金屬奈米複合物確實形成。再以Raman光譜鑑定其石墨化程度及XRD定性金屬奈米複合物之晶型結構為面心立方體。 隨後基於將金屬奈米複合物會協助反應物的吸附以提升催化效果的特性，對其作為光觸媒所需的光源作試驗，以提供金屬奈米複合物作為光觸媒之光源選擇的依據，並且在以可見光光源照射下，可以在10小時內使銀奈米複合物對亞甲基藍達到56%的吸附降解，而金-石墨烯及金-氧化石墨烯奈米複合物則在64小時內對亞甲基藍達到86%及90%的降解率；而使用仿太陽光光源照射，則使銀奈米複合物及金-石墨烯/氧化石墨烯奈米複合物在10小時內分別對亞甲基藍達到74%及95%的吸附降解。最後，也利用合成的奈米銀與細菌體蛋白質上硫氫基的特異性結合可有效抗菌的特性，分別對大腸桿菌與金黃葡萄球菌做抗菌試驗(Agar Diffusion Method)，抑菌圈為17.64π和16.81π，且其效果與市售抗菌液產品接近。
並列摘要
In this study, two methods were used to prepare metal nanoparticle composites, one using laser induction and the other being biosynthesis. The two preparation methods do not require the use of organic solvents. The reagents and materials are also quite environmentally friendly, and the preparation method is relatively simple and convenient. Therefore, two kinds of metal nanocomposites responding to green chemical environmental protection issues were prepared, and one of the recovered agricultural wastes - banana pseudo-stem cores was determined to have a total phenol content of 2.7 mg/g (gallic acid equivalent / dry weight). The Ag nanoparticles were well-characterized by UV-visible absorption spectroscopy, showing an SPR band centered at 420-nm. TEM analysis further shows that the nanocomposite is decorated with Ag nanoparticles (averaged size ~ 10 nm). Moreover, EDS analysis proves the elemental composition for the nanocomposite, and XRD analysis reveals the face-centered cubic (fcc) crystal structure for the Ag nanoparticles. Cyclic Voltammetry (CV) found that oxidation of 0.26 V Ag (0) to Ag (+) confirmed that silver nanoparticles were synthesized. And at -0.6 V, it was found that the reduction peak of Ag (+) was reduced to Ag (0) by the natural-OH group. This result indicates that the banana pseudo-stem tender core does form a silver nano-composite with silver, and thus it is known that it has redox characteristics and is suitable for use as an antibacterial agent. Second, the Au-G/Au-GO nanocomposites were prepared by ND：YAG pulsed laser induction, and the UV-Visible absorption spectrum was confirmed the formation of the metal nanocomposites, and it is observed from the light gray to the purple. The average particle size of the gold-graphene and gold-graphene oxide nanocomposites can be calculated by TEM. Depending on the conditional parameters, it is about 2 nm to 33 nm and EDS showed the single point contains gold and reaffirmed that the metal nanocomposite did form. XRD was identified as Au-G/Au-GO nanocomposites as face-centered cubes. Subsequently, we assumed that the metal nanocomposite has the catalytic power, the photocatalysis test was operated under different light sources, including 365 and 470-nm LEDs and simulated solar light. Under the illumination of the 470-nm LED and solar simulator, the silver nanocomposite can adsorb and degrade 56% and 74% methylene blue (MB) within 10 hours, but no effective degradation was observed by using a 365-nm LED. Additionally, under the illumination of the 470-nm LED, the gold-graphene and gold-graphene oxide nanocomposite can degrade 86% and 90% methylene blue (MB) within 64 hours, respectively. At last, while under the illumination of the solar simulator, both the Au-G/Au-GO nanocomposites can degrade 95% methylene blue within 64 hours. This suggests that irradiating the SPR band of metal nanocomposites with suitable wavelengths is crucial to effective photocatalysis and dye degradation. Finally, we also examined the antibacterial property of the nanocomposites through an agar diffusion method. The inhibition zone for Escherichia coli and Staphylococcus aureus was found to be 17.64π, 16.81π, respectively. This effect is comparable to the commercially available products based on an aqueous solution of silver ions.