| Summary: | 碩士 === 國立中央大學 === 材料科學與工程研究所 === 97 === In this study, the sol-gel and spin coating methods are used to prepare α-Fe2O3 thin film that is used as a photoelectrode for photoelectrochemical (PEC) production of hydrogen. Effects of platinum (Pt) doping are also studied. α-Fe2O3 has a narrow band gap of 2.2eV; it can absorb solar insolation of wavelength smaller than 564 nm, which accounts for approximately 30% of solar insolation. Furthermore, α-Fe2O3 is a stable oxide. It has a good resistance against light exposure and chemical corrosion, and therefore it has a long lifetime.
The sol-gel method is a simple and low-cost method for precursor preparation. The resulting gel is deposited on FTO by spin coating. In this study, the effects of spin rate, heat treatment temperature and atmosphere, and the doping amount of Pt in iron oxide on the crystal structure, morphology, optic property, and PEC performance are investigated.
The results of XRD and XPS show that α-Fe2O3 can be obtained using 500oC annealing in air or oxygen. At 500 nm, the iron oxide film has a thickness of 228 nm, a band gap of 2.02 eV, and an absorptance of 50 %. As for the PEC performance, the measured photocurrent density is 0.50 mA/cm2 for the undoped iron oxide film with a bias voltage of 0.5V(V vs. Ag/AgCl). Doping of Pt can enhance the crystalline of iron oxide. Increasing the Pt amount reduces the grain size and band gap. With a bias voltage of 0.5V(V vs. Ag/AgCl), the photocurrent density is 0.7 mA/cm2 for the 0.1%-Pt-doped film.
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