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Zhang J, Winget SA, Wu Y, et al. Ag@Au Concave Cuboctahedra: A Unique Probe for Monitoring Au-Catalyzed Reduction and Oxidation Reactions by Surface-Enhanced Raman Spectroscopy. ACS Nano. 2016;10(2):2607-16doi: 10.1021/acsnano.5b07665.
Zhang, J., Winget, S. A., Wu, Y., Su, D., Sun, X., Xie, Z. X., & Qin, D. (2016). Ag@Au Concave Cuboctahedra: A Unique Probe for Monitoring Au-Catalyzed Reduction and Oxidation Reactions by Surface-Enhanced Raman Spectroscopy. ACS nano, 10(2), 2607-16. https://doi.org/10.1021/acsnano.5b07665
Zhang, Jiawei, et al. "Ag@Au Concave Cuboctahedra: A Unique Probe for Monitoring Au-Catalyzed Reduction and Oxidation Reactions by Surface-Enhanced Raman Spectroscopy." ACS nano vol. 10,2 (2016): 2607-16. doi: https://doi.org/10.1021/acsnano.5b07665
Zhang J, Winget SA, Wu Y, Su D, Sun X, Xie ZX, Qin D. Ag@Au Concave Cuboctahedra: A Unique Probe for Monitoring Au-Catalyzed Reduction and Oxidation Reactions by Surface-Enhanced Raman Spectroscopy. ACS Nano. 2016 Feb 23;10(2):2607-16. doi: 10.1021/acsnano.5b07665. Epub 2016 Jan 28. PMID: 26812215.
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ACS Nano. 2016 Feb 23;10(2):2607-16. doi: 10.1021/acsnano.5b07665. Epub 2016 Jan 28.

Ag@Au Concave Cuboctahedra: A Unique Probe for Monitoring Au-Catalyzed Reduction and Oxidation Reactions by Surface-Enhanced Raman Spectroscopy.

ACS nano

Jiawei Zhang, Sarah A Winget, Yiren Wu, Dong Su, Xiaojun Sun, Zhao-Xiong Xie, Dong Qin

Affiliations

  1. School of Materials Science and Engineering, Georgia Institute of Technology , Atlanta, Georgia 30332, United States.
  2. State Key Laboratory of Physical Chemistry of Solid Surfaces and Department of Chemistry, Xiamen University , Xiamen, Fujian 361005, PR China.
  3. Department of Chemistry, Agnes Scott College , 141 E College Avenue, Decatur, Georgia 30030, United States.
  4. Center for Functional Nanomaterials, Brookhaven National Laboratory , Upton, New York 11973, United States.

PMID: 26812215 DOI: 10.1021/acsnano.5b07665

Abstract

We report a facile synthesis of Ag@Au concave cuboctahedra by titrating aqueous HAuCl4 into a suspension of Ag cuboctahedra in the presence of ascorbic acid (AA), NaOH, and poly(vinylpyrrolidone) (PVP) at room temperature. Initially, the Au atoms derived from the reduction of Au(3+) by AA are conformally deposited on the entire surface of a Ag cuboctahedron. Upon the formation of a complete Au shell, however, the subsequently formed Au atoms are preferentially deposited onto the Au{100} facets, resulting in the formation of a Ag@Au cuboctahedron with concave structures at the sites of {111} facets. The concave cuboctahedra embrace excellent SERS activity that is more than 70-fold stronger than that of the original Ag cuboctahedra at an excitation wavelength of 785 nm. The concave cuboctahedra also exhibit remarkable stability in the presence of an oxidant such as H2O2 because of the protection by a complete Au shell. These two unique attributes enable in situ SERS monitoring of the reduction of 4-nitrothiophenol (4-NTP) to 4-aminothiophenol (4-ATP) by NaBH4 through a 4,4'-dimercaptoazobenzene (trans-DMAB) intermediate and the subsequent oxidation of 4-ATP back to trans-DMAB upon the introduction of H2O2.

Keywords: Au-catalyzed reduction and oxidation; concave nanocrystal; seed-mediated growth; surface capping; surface-enhanced Raman spectroscopy

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