Electrochemically fabricated gold dendrites with underpotential deposited silver monolayers for a bimetallic SERS-active substrate

Ying Huang Lai, Shan Chi Kuo, Yun Ching Hsieh, Yu Chun Tai, Wei Hsiu Hung, U. Ser Jeng

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Abstract

With electrochemical deposition, cysteine-directed crystalline gold dendrites (Au-Ds) on glassy carbon electrodes were fabricated. The Au-Ds surfaces were further modified with Ag adatoms by underpotential deposition (UPD) for Ag-covered Au-Ds (Ag-Au-Ds). The Ag-Au-Ds possessed a hierarchical architecture comprising trunks, branches, and nanoleaves for a threefold-symmetry, resulting in a high density of sharp tips and edges for hot spots of surface-enhanced Raman scattering (SERS). Prominent SERS was observed with p-nitrothiophenol (p-NTP) adsorption onto either Au-Ds or Ag-Au-Ds, for a best p-NTP detection limit down to 5-10 nM at 785 nm laser excitation. However, at specific 633 nm laser excitation, SERS with p-NTP adsorption on Ag-Au-Ds exhibited a three-fold higher enhancement over that measured for p-NTP adsorbed on unmodified Au-Ds, suggesting an increased chemical SERS enhancement with the Ag-p-NTP bonding. Furthermore, adsorption isotherms of p-NTP with Au-Ds and Ag-Au-Ds adsorption in solution are established from solution p-NTP-concentration dependent SERS; from which, comparable binding constants of p-NTP to Au-Ds and Ag-Au-Ds are extracted.

Original languageEnglish
Pages (from-to)13185-13192
Number of pages8
JournalRSC Advances
Volume6
Issue number16
DOIs
Publication statusPublished - 2016 Jan 1

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ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)

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