Surface Plasmon Resonance of Gold/ SiO2/ CdS Core-Shell Nanoheterostructures : interfacial charge carrier dynamics and photocatalysis

• Main Authors: Guo, Dai-Yun, 郭岱昀
• Other Authors: Pu, Ying-Chih
• Format: Others
• Language: zh-TW
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/3n3q3p

碩士 === 國立臺南大學 === 材料科學系碩士班 === 107 === In the gold (Au)/semiconductor nanoheterostructure, the surface plasmon resonance (SPR) of the Au can improve the photoelectric conversion efficiency of the semiconductor. There are many explanations for its mechanism, including hot electron transfer, local electric field enhancement, resonance energy transfer and so on. Among them, the resonance energy transfer mechanism has not been clarified and actually applied to photoelectric conversion. Therefore, this study uses solid gold nanoparticle (SGN) and hollow gold nanoparticle (HGN) to coat the appropriate thickness of cerium oxide (SiO2) and cadmium sulfide (CdS) shells to form three-layer core-shell nanostructure of /SiO2/CdS and HGN/SiO2/CdS. The crystal structure, optical characteristic and excited state carrier property were systematically studied and the relationship between SPR and CdS carrier transfer and photocatalytic degradation of p-nitrophenol (PNP) were also discussed. The analysis by transmission electron microscopy (TEM) and X-ray diffraction (XRD) confirmed that SGN/SiO2/CdS and HGN/SiO2/CdS were successfully prepared. Wherein, the SiO2 insulating layer blocks the excited state electrons of CdS from the conduction band to the central core-Au, so that the excited electrons can stay in the CdS shell and be utilized in photocatalysis. In the three-layer heterostructure, the SPR absorption peaks of SGN and HGN are 568 nm and 615 nm, and there is no overlap with the band edge absorptionof the CdS(<520nm), when the excitation light corresponds to SPR, the nanoheterostructures exhibit significant photocatalytic activity. In addition, when the nanostructure is measured by time-resolved photoluminescence (TRPL), the fluorescence lifetime of the CdS shell is increased after the incident light corresponding to the SPR wavelength is applied. It is confirmed that even if the incident light energy of the SPR absorption wavelength of the core Au is not larger than the energy gap of the CdS, the energy can still transfer to the CdS by energy resonance transfer and an additional excited state carrier is generated to prolong the life cycle. This result confirms that metal SPR enhances semiconductor photoelectric conversion through the mechanism of energy resonance transfer, and is practically applied in photocatalysis, and in which carrier kinetics studies can provide information for designing metal/semiconductor nano-heterostructures and expand their applications in optoelectronics.