Enriching Silver Nanocrystals with a Second Noble Metal
讲座名称：
Enriching Silver Nanocrystals with a Second Noble Metal
讲座时间：
2017-07-06
讲座人：
秦冬
形式：
校区：
兴庆校区
实践学分：
讲座内容：
讲座名称：Enriching Silver Nanocrystals with a Second Noble Metal
讲座时间：2017年7月6日，上午10：30
讲座地点：科学馆207，兴庆校区
讲座人：秦冬 副教授；佐治亚理工学院
讲座内容：Silver is perhaps the best choice of material for plasmonics and related applications owing to its relatively low cost and favorable dielectric functions. Over the past two decades, significant progress has been made in the synthesis of Ag nanocrystals with controlled shapes and sizes to tailor their properties and thus optimize their performance in a range of applications. In particular, Ag nanocrystals have been prepared with sharp features (e.g., edges and corners) on the surface to drastically augment their surface-enhanced Raman scattering (SERS) activity. However, the sharp features tend to vanish due to the high susceptibility of Ag toward oxidative etching. As another pitfall, Ag is limited in terms of catalytic application as it only shows activity toward oxidation reactions such as epoxidation, not reduction reactions. One can address the aforementioned limitations of Ag nanocrystals by introducing a second noble metal (M) such as Au, Pd, or Pt to generate Ag-M bimetallic nanocrystals. In this talk, I will introduce two approaches to using Ag nanocrystals as seeds for the selective deposition of M. When the M atoms are selectively deposited on the edges of a Ag nanocrystal, a Ag@M core-frame nanocrystal is formed. In this structure, the excellent plasmonic and SERS properties of the Ag core are well retained while the deposited M can bring in new catalytic capabilities. Alternatively, when the M atoms are conformally deposited on the entire surface, a Ag@M core-shell nanocrystal is created. In this case, the M shell can greatly improve the chemical stability of the particle, in addition to the new catalytic properties associated with M. If the shell is kept below 1–2 nm thick, the excellent plasmonic and SERS properties of the Ag core can still be leveraged. Significantly, both SERS and catalytic properties can be integrated in the core-frame and core-shell nanocrystals to offer a unique probe for in situ detection and analysis of catalytic reactions by SERS.
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