| Summary: | 碩士 === 國立臺灣科技大學 === 化學工程系 === 102 === In this work, photoanodes of tungsten oxide(WO3) catalyst with different surface morphologies have been prepared on fluorine-doped tin oxide (FTO) substrates by electron beam evaporation, solvothermal and hydrothermal method. Photoelectric chemical analysis results carried out at 1.23 V vs. reversible hydrogen electrode (RHE) showed that the sheet-like WO3 film synthesized by hydrothermal method has the best performance. It produces a photocurrent of 0.91 mA/cm2 under simulated sun light (AM1.5G, 100 mW/cm2), higher than the current density 0.69 mA/cm2 of dense WO3 film synthesized by electron beam evaporation and 0.77 mA/cm2 of hedgehog-like WO3 films synthesized by solvothermal method.
In photocathode catalysts part, Cu2O film with (111) preferred orientation was electrodeposited on FTO with the existence of chelating agents(lactic acid). Chelating agents are indispensable in the process of electrodeposition of Cu2O in order to obstruct the precipitation of Cu(OH)2 in alkaline bath and stabilize Cu (II) ions. Photoelectric chemical analysis results showed that Cu2O film of 3 μm thickness has the best performance at 0.00 V (vs. RHE) and it produces a photocurrent of -0.20 mA/cm2.
Finally, the prepared WO3 photoanode and Cu2O photocathode were applied in New Solar Cell (NSC) system, which has been developed by our lab. Free electron-hole pairs are generated when the photoelectrodes are exposed under solar light. The electrons and holes are capable of reacting with the redox-pairs in the electrolyte of two separate chambers, leading the occurrence of reduction and oxidation in the electrolytes to fuel the intrinsic galvanic cell within the NSC for power generation. After investigation by potential static equipment, the NSC cell has an open circuit voltage of 0.37 V with the exposed area of 0.56 cm2. It was found that the short circuit current density was 1.33 x 10-3 mA/cm2.
In addition, the effects of the electrolyte composition for the NSC system were also of concern. It was investigated by applying the pre-purge gas in the electrolyte. The results show that NSC has the best performance when the system is under oxygen-rich and hydrogen-rich state at the same time. In this case, the maximum open circuit voltage was able to increase to 0.45 V and short circuit current density was around 3.00 x 10-3 mA/cm2
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