Professor Dong Qin, School of Materials Science and Engineering, Georgia Institute of Technology

Enriching Silver Nanocrystals with a Second Noble Metal
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 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 towards oxidative etching. As another pitfall, Ag is limited in terms of catalytic application as it only shows activity towards oxidation reactions such as epoxidation, not reduction reactions. By introducing a second noble metal (M) such as Au, Pd, or Pt to generate Ag-M bimetallic nanocrystals, one can address the aforementioned limitations of Ag nanocrystals. In this talk, I will present two strategies for the generation of Ag-M bimetallic nanocrystals. When the M atoms are selectively deposited on the edges of a Ag nanocrystal, for example, a Ag@M core-frame nanocrystal is formed. In this structure, the excellent plasmonic and SERS properties of the Ag core are still retained while the deposited M brings 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 while presenting new catalytic properties associated with M. 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. Building upon the prior success, I will also report our recent development of metal-sensitive SERS probes for better understanding the heterogeneous nucleation and early-stage deposition of metal atoms (M) on the silver cubic seeds in solution.

Short bio:
Dong Qin is a Professor of Materials Science and Engineering at the Georgia Institute of Technology (GT), with an adjunct appointment in the School of Chemistry & Biochemistry. Her academic records include a B.S. in Chemistry from Fudan University (1990), a Ph.D. in Physical Chemistry with Professor Hai-Lung Dai from University of Pennsylvania (1996), a postdoctoral stint with Professor George M. Whitesides at Harvard University (1996–1997), and an MBA from the University of Washington (2003).
Before joining GT in 2012, she held administrative positions as Associate Dean for Research in the School of Engineering and Applied Science at Washington University in St. Louis (2007–2011) and Associate Director of Center for Nanotechnology at the University of Washington (2002–2007).
Dr. Qin has pioneered a set of in situ techniques for the characterization of atomic/molecular events on the surface of noble-metal nanocrystals in a liquid phase and under operando conditions. She is widely recognized for her many original contributions to the rational synthesis of metal nanocrystals with novel properties.
Dr. Qin is an Associate Editor of Nanoscale, Royal Society of Chemistry (RSC) and was elected a Fellow of Royal Society of Chemistry (FRSC) in 2021. Dr. Qin is a recipient of the GT-Class of 1940 W. Roane Beard Outstanding Teacher Award (2020), GT-Provost Teaching and Learning Fellow (2018), GT-Geoffrey G. Eichholz Faculty Teaching Award (2018), and GT-CETL/BP Junior Faculty Teaching Excellence Award (2015).