本論文研究保護劑分子對金奈米粒子表面特性的影響；這些表面的差異性會反映在奈米粒子在毛細管電泳的遷移時間，以及其催化活性。四種保護劑分別是SDS，檸檬酸，mercaptosuccinic acid(MSA)，sodium 2-mercaptoethanesulfonate(SMES)。電泳實驗發現 SDS 與檸檬酸對奈米粒子提供較多的表面負電荷，而硫醇分子修飾量的增加會造成表面電荷減少。同時，修飾硫醇分子的奈米粒子與 NaBH4 進行反應，會造成硫醇分子不可逆的脫附。另外，添加由 SDS 製的未修飾奈米粒子有助於少量修飾硫醇分子的脫附，而粒徑大於 10 nm 的檸檬酸製奈米粒子無法幫助脫附硫醇分子。最後，蒽分子的氫化實驗結果發現修飾 MSA 的金奈米粒子會降低其催化活性，而還原劑 NaBH4 使 MSA 脫離金奈米粒子表面後，其催化活性可完全恢復，此結果顯示了硫醇分子可能是與金原子鍵結後脫離粒子的表面，粒子表面因此恢復乾淨狀態，可以再度進行修飾。 This thesis studies the influence of the protecting molecules on the surface properties of gold nanoparticles (Au NPs), reflecting in the changes of the mobilities in capillary electrophoresis and the activities in catalyis. The stabilizers - SDS, citric acid, mercaptosuccinic acid (MSA) and sodium 2-mercaptoethanesulfonate (SMES) are employed in the study. The surface charges of the Au NPs capped by SDS and citric acid are more negative than those by thiol molecules. When the latter react with NaBH4, the thiol molecules could be irreversibly desorbed from the surface of the Au NPs at the same time. But the similar phenomenon could not be observed for Au NPs prepared by citric acid whose size is bigger than 10 nm. On the other hand, the desorption of the thiol molecules for all the thiol-modified Au NPs could be initiated and accelerated by adding the Au NPs prepared by SDS. Finally, experimental results show that the catalytic activity of the MSA-modified Au NPs is lower than that of the Au NPs capping by SDS in the hydrogenation reaction of anthracene. And their catalytic activity can remain the original high activity after the addition of the reductant reagent, NaBH4, resulting the desorption of MSA on the surface of Au NPs. These results suggest the thio-compound may bind with an Au atom in the process of desorption. Therefore, both the clean surface and the catalytic activity of Au NPs could be obtained.
