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| Abstract Title:
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| Detecting Molecular Transformations with Gold Nanoshells
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| Graduate Student Presenter:
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Kimberly N. Heck
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| Name of the Author(s) and Affiliation(s):
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Kimberly N. Heck, Rice University; Benjamin Janesko, Rice University; Gustavo E. Scuseria, Rice University; Naomi J. Halas, Rice University; Michael S. Wong, Rice University
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Understanding of the interaction of reactant molecules with heterogeneous catalysts in aqueous environments offers the potential to improve catalyst designs, however characterization of catalyst-reactant interactions remains a challenge. While surface-selective methods such as EELS or FTIR/ATR have been used successfully to monitor to the adsorption of compounds to model catalyst sites, the techniques require the use of artificial ultra high vacuum or water-free environments. Surface-enhanced Raman spectroscopy (SERS) using gold nanoshells, on the other hand, could provide the requisite sensitivity for analyzing aqueous catalyzed reactions in-situ. Au nanoshells are a class of SERS substrates, whose surface plasmon resonance (SPR) can easily be tuned by modifying core size and shell thickness, resulting in signals up to 10^14 times greater than normal Raman.
In this paper, we report the synthesis of Pd-decorated Au nanoshells to mimic the catalytic behavior of Pd-on-Au nanoparticle catalysts, which have been shown to be an effective catalyst for groundwater remediation of chlorinated ethylenes. Time-resolved SERS spectral analyses indicate that chemisorption and surface reaction events of dichloroethylene (DCE) probe molecule can be observed. It appears that 1,1-DCE adsorbs to the Pd catalyst via pi-bonding with Pd atoms on the surface, for example. The results of this study highlights the promising use of SERS spectroscopy of metal-catalyzed reactions in water in-situ.
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