| Summary: | 碩士 === 國立中興大學 === 化學系所 === 97 === The Master thesis research work carried out here is divided into two major parts, the first part focuses on the development of composite gold-titanium dioxide (TiO2) nanoparticles (nano-Au/TiO2) and the second part deals with its application as an electrochemical sensor. We use tetrachloroauric acid solution (HAuCl4) as a precursor in photo- reduction of gold nanoparticles on TiO2. The gold nano particles size can be varied by exposure of UV light irradiation time, pH values and different concentration of methanol. The as prepared composite gold-titanium dioxide nanoparticles are then characterized for morphological aspects by Transmission Electron Microscopy (TEM) and Energy Dispersive Spectrometer (EDS). The synthesized composite nano particle were found to be about 5-10 nm in size. Previous works addressed about the preparation of gold nanoparticles on TiO2, with the addition of reducing reagents (like NaBH4 and sodium citrate) or organic solvents in the process, some methods even need heating to accelerate the reduction rate of metal nanoparticles, and also use complicated process of annealing or calcination at high temperature for making gold nanoparticles on the surface of TiO2. Compared to these works, the advantages of our proposed method including no tedious process involved or heating while in the preparation step without the addition of any reducing agents.
In the second part, the as prepared nano-Au/TiO2 powder is mixed with isopropanol solution and ultrasonicated, 3 uL of ultrasonicated mixture is then directly dip-coated on a screen printed carbon electrode, The nano-Au/TiO2 electrode is then used for electrochemical studies combined with flow injection analysis (FIA) for the analysis of epinephrine. Voltammetric studies and FIA provides a very good sensitive method for the determination of epinephrine and the linear range was found to be 1 uM ~ 300 uM with a detection limit of 0.05 uM.
At the same time, an attempt is made to prepare nano-Au/TiO2, combined MnO2 screen printed ring-disk electrode (SPRDE) for electrochemical studies. The ring of the electrode is modified with MnO2 and disk with nano-Au/TiO2. The modified electrode exhibits excellent electrocatalytic response to the reduction of oxygen and hydrogen peroxide.
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