| Summary: | 碩士 === 國立中央大學 === 化學工程與材料工程學系 === 106 === Our society is facing growing challenges of energy and environment. In order to find clean and renewable energy resources instead of fossil fuels, many researchers worked hard and tried to find a way to solve the problem. Among these renewable energy resources, the biggest potential to develop is solar energy due to the endless of sun irradiation. To store the solar energy is another problem. One of the solutions is converting solar energy to chemical energy. So we use water-splitting photocatlyst to produce hydrogen under sun irradiation for energy storage. Hydrogen is a clean energy resource because it only produces water and energy after combustion.
ZnIn2S4 (ZIS) is a visible-light-driven photocatalyst with the energy band gap of 2.4 eV. We developed a microwave-assisted hydrothermal method to generate ZIS particles. In particular, our studies showed that the gold-silver nanoshells with SiO2 shell(GSNS@SiO2) embedded in ZIS matrix exhibited a unique plasmonic-enhanced photocatalytic hydrogen production. However, the coverage and thickness of ZIS on top of GS-NS were not precisely controlled. If we improve the crystallinity and coverage of ZIS to control shell thickness of ZIS, we can find out the factor which could affect hydrogen production efficiency. Because GSNS@SiO2 is hard to synthesize, our research is focusing on SiO2 core instead of GSNS@SiO2.
We found that SiO2@ZIS synthesized in pure water solution has better crystallinity, though synthesized in pure ethanol solution has better coverage. Adding HCl into both water and ethanol solution to lower pH condition would increase crystallinity, better crystallinity related to better hydrogen production efficiency. SiO2@ZIS synthesized in ethanol-water mixed solution would combine the advantage of two solutions, but the properties of the samples were too complex to analyze. Though ZIS shell could get thicker by repeating coating ZIS synthesized in different ratio of ethanol-water solution, not precisely controlling ZIS shell and only outer ZIS shell participating water-splitting reaction limited the use of repeating coating method. Finally we could increase crystallinity and coverage of SiO2@ZIS by adding HCl into pure ethanol solution, ZIS shell thickness could also be controlled by different concentration of ZIS precursor. However, due to the different properties between SiO2 core and GSNS@SiO2, it takes time to study SiO2@ZIS synthesis process applied to GSNS@SiO2. Thus, our facile procedure paves the way to generate a more complex structure GS-NS@dielectric@ photocatalyst, for optimization of solar hydrogen production.
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