| Summary: | 碩士 === 國立東華大學 === 材料科學與工程學系 === 104 === In this study , we use microwave–assisted to prepare O2 evolution photocatalyst, BiVO4. H2 evolution photocalyst use SSK4Nb6O17. The characterization of as-prepared BiVO4 was carried out by X-ray diffraction (XRD), Field Emission Scanning electron microscope (FE-SEM), ultraviolet-visible analyzer(UV-vis) and Surface Area & Mesopore Analyzer(BET) .
In the process of photocatalyst synthesis, regulation of nitric acid concentration, temperature, and time as a different synthetic condition. Synthesis of time increases by the cubic morphology BiVO4 photocatalyst massive agglomeration into spherical structure and increasing the particle size. Synthesis of nitric acid concentration increased BiVO4 photocatalyst particles produced spherical agglomeration structure. Synthesis reaction temperature is increased to BiVO4 photocatalyst particle morphology little effect. With the synthesis reaction time stretched BiVO4 photocatalyst reduce the band gap. Synthesis of nitric acid concentration and temperature for BiVO4 photocatalyst band gap has little effect. Preparation impregnated with Pt/BiVO4 photocatalyst, Pt average particle size 17nm, evenly spread over the surface of the BiVO4 photocatalyst. Pt/BiVO4 photocatalyst was prepared by photodeposition method. Pt particles selectively deposited on {010} planes BiVO4 photocatalyst. Pt/BiVO4 photocatalyst optical absorption edge will move longer wavelength .
Synthesis of nitric acid concentration increased, BiVO4 photocatalytic reaction rate decreases oxygen production. Synthesis of reaction temperature increases, BiVO4 photocatalytic reaction rate increased oxygen production. Synthesis of reaction temperature BiVO4 photocatalytic reaction rate on oxygen production is very important.
The BiVO4(0.5M 180℃1hr) photocatalyst has the best photocatalytic reaction rate of oxygen production in AgNO3 aqueous solution. A O2 evolution rate of 2622 μmoleg-1h-1.
Pt photodeposited BiVO4 photocatalyst was better than pure BiVO4 photocatalyst, the photocatalytic reaction rate of oxygen production was up 2 times in 5mM NaIO3 aqueous solution.
Z-scheme system consist to hydrogen production catalyst (0.5wt%Rh/SSK4Nb6O17) and oxygen production catalyst(Pt/BiVO4). We found the Z-scheme photocatalysis system with 0.5wt%Pt-BiVO4-0.5wt%Rh/SSK4Nb6O17 photocatalysts exhibited a highest photoactivity with a H2 evolution rate of 348 μmole g-1 h-1 and a O2 evolution rate of 172 μmole g-1 h-1.
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