:::
1091-專題演講-1091014-陳詩芸（台科大材料系）
演講活動
張貼人：李明芳 ╱ 公告日期：2020-08-18|
Time：1091014 (Wed.) 14:20~16:20
Speaker：Prof.陳詩芸(CHEN, Shih-Yun)
國立臺灣科技大學材料科學與工程系/Department of Materials Science and Engineering, National Taiwan University of Science and Technology
Title：Magnetism and plasmonic performance of mesoscopic hollow ceria spheres
Abstract：Firstly, magnetism of mesoscopic hollow ceria sphere with different defect distribution was investigated. Micro-scale hollow spheres were synthesized by spray pyrolysis and then immersed in 1 M HNO3 for different times. The content and distribution of defect were investigated by complementary microscopic and spectroscopic analysis. It is demonstrated that the value of saturation magnetization varies with sphere structure, including defect distribution character and surface roughness. The strongest magnetism was obtained in the sample subjected to react with 1 M HNO3 for 60 minutes, in which Ce3+ aggregates within a narrow defective layer at surface and the sphere surface is smooth. It thus implied that in micro-scale hollow sphere, surface plays the major role in its magnetic behavior.
Next, the role of interfaces and surfaces on the surface enhanced Raman spectroscopy (SERS) properties of CeO2 hollow spheres decorated by Ag nanoparticles (H-CeO2@Ag) were investigated. The composites, H-CeO2@Ag, were synthesized using a newly developed two-step process. Spectroscopic and microscopic characterization confirms the formation of an interface between the Ag and ceria and shows different charge rearrangements occurring at both the interface and surface. Strong SERS effect was reported with a detection limit down to 10-14 M for rhodamine 6G analytes. Scanning transmission electron microscopy and electron energy loss spectroscopy investigation reveals that hot-spots are associated with the silver NPs surfaces and also with Ag/ CeO2 interface. This interfacial hot spot occurs for metallic particles above 30 nm and is strongly red shifted with respect to the Ag surface plasmon. The strong SERS activity is then attributed to the presences of several types of hot-spots and the geometrical features (buoyant hollow sphere, size dispersion) of the composite.
Place：B101, Gongquan Campuses, NTNU
|
最後修改時間：2020-10-12 PM 2:35
