| Summary: | 碩士 === 中原大學 === 化學研究所 === 101 === The first part of this study was the preparation of graphene. We prepare few-layer stacked graphene sheet mainly using redox method. We first exfoliated graphite into graphene-oxide nano sheet by using Hummers method. Then, using titanium(III) ions dissolved from titanium metallic powder in acid solution, to reduce graphene-oxide. We found that when the system is in the simultaneous existence of titanium metal and titanium (III) ions, the reduction ability is much higher than the reaction system containing only titanium (III) ions. From X-ray photoelectron spectroscopy analysis, we confirmed that when the titanium and titanium (III) ions was coexist, the reduced-graphene has a very high carbon to oxygen ratio (23.44).
The second part of this study was the prepartion of graphene electrode by using titanium(III) ions reduction method, and applied to the counter electrode of dye-sensitized solar cells. In this part, we have prepared two different structures of the graphene electrode, one is a dense structure, another one is a porous structure. The photoelectric conversion efficiency of dense structure was 1.61%, while the porous structure was 5.45 %, which was comparable to the platium electrode (5.52 %). We use field emission scanning electron microscopy, electrochemical impedance spectra and cyclic voltammetry to investigated into how the porous structure affect the photoelectric conversion efficiency. In the final of this chapter, we further loaded a small amount of platinum particles at graphene nano sheet, and its efficiency can be raised to 5.87%.
The third part of this study was the flexible dye-sensitized solar cells. First, we exame the durability of the flexible Pt-graphene electrode by bending it for 1500 times. Aftter 1500 times bending, the photoelectric conversion efficiency of the Pt-graphene electrode decayed from 5.75 % to 5.09 %. Then, we prepared a flexible TiO2 working electrode, and through a series of optimization treatment, the photoelectric conversion efficiency was achieve 4.85 %(the counter electrode was Pt). We further replace Pt electrode by Pt-graphene electrode, and the photoelectric conversion efficiency was raised to 5.30 %.
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