The Center for Nanoscale Materials holds a regular biweekly colloquium on alternate Wednesday afternoons at 4:00 p.m. in Bldg. 440, Room A105/106. The goal of the series is to provide a forum for topical multidisciplinary talks in areas of interest to the CNM and also to offer a mechanism for fostering interactions with potential facility users. Refreshments will be served at 3:45.
March 12, 2014
“Ag-Au Bimetallic Nanocubes with Enhanced SERS Property and Chemical Stability," by Dong Qin, Georgia Institute of Technology, hosted by Yugang Sun
Abstract: Surface-enhanced Raman scattering (SERS) relies on the localized surface plasmon resonance and enhancement of electromagnetic fields around metal nanostructures to drastically increase the Raman scattering cross sections of molecules in close proximity to the nanostructures. It has been documented that silver nanocubes embrace SERS properties with enhancement factors up to 106 at visible excitation wavelengths for highly sensitive detection of chemical or biological species. Unfortunately, elemental silver is highly susceptible to oxidation under conditions that involve oxidants, halide ions, acids, water, ultraviolet irradiation, and heating. Such chemical instability often results in changes to the morphology of silver nanostructures, particularly at corners and edges with high surface free energies, and ultimately compromise their performance in SERS. One potential solution to improve the chemical stability of silver nanostructures is to form alloy with a more stable metal such as gold. In this talk, I will report an approach to complementing the galvanic replacement reaction between silver nanocubes and HAuCl4 with co-reduction by a reducing agent for the formation of Ag-Au hollow nanostructures with enrichment of silver to greatly enhance SERS activity. Additionally, I will report our latest development in the replacement-free seeded growth of gold on silver nanocubes with excellent SERS property and chemical stability.