| Summary: | 碩士 === 臺灣大學 === 化學工程學研究所 === 98 === Hydrogen generation from photocatalytic water splitting has been so called the “artificial photosynthesis”, a green process that is promising and clean. The Z-scheme system is comprised of H2-catalyst and O2-catalyst with aid of electron transfer mediator to produce hydrogen and oxygen, respectively, mimicking the two step photosynthesis process. It shows that the seperation of H2-catalyst and O2-catalyst in two discrete chamber by Nafion ion-exchange membrane can efficiently increase the gas evolution rate due to backward reaction elimination from preveous research. In this report, the iron mediator transfer phenomenon through Nafion membrane was analyzed by colorimetry method quantitatively. The derived diffusion rates for irons were remarkably larger than photocatalytic hydrogen producing rate, indicating the real water splitting reaction. Besides, by applying different O2-catalyst (WO3 and BiVO4) along with H2-catalyst (Pt/SrTiO3:Rh) in water splitting reaction, the rate determining step has been shown to lie in H2-catalyst part. Furthermore, the twin reactor device can not only produce hydrogen and oxygen simultaneously in two chambers under visible light irradiation, but also eliminate the chance for light source competition between photocatalysts. Under the optimal condition, the hydrogen rate reached 0.88μmol/g．hr, and the deactivation could be negligible during 12 hours reaction time.
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