Long range self-organisations of small metallic nanocrystals for SERS detection of electrochemical reactions

Gold electrodes were modified by silver and gold nanocrystals (NCs) that self-organize onto the surface. Their optical properties were explored by measuring electroreflectance spectra as a function of electrode potential. Below their oxidation potential, no shift of the reflectance maximum was obser...

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Bibliographic Details
Published in:Journal of electroanalytical chemistry (Lausanne, Switzerland) Switzerland), 2020-09, Vol.872, p.114322, Article 114322
Main Authors: Groni, Sihem, Fave, Claire, Schöllhorn, Bernd, Chapus, Lionel, Aubertin, Pierre, Touzalin, Thomas, Lucas, Ivan T., Joiret, Suzanne, Courty, Alexa, Maisonhaute, Emmanuel
Format: Article
Language:English
Subjects:
Chemical reactions
Chemical Sciences
Electrode potentials
Electrodes
Electrolytes
Electron transfer
Gold
Hydrophobicity
Molecular electrochemistry
Nanocrystals
Optical properties
Silver
Single electrons
Spectroelectrochemistry
Surface enhanced Raman spectroscopy
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Summary:Gold electrodes were modified by silver and gold nanocrystals (NCs) that self-organize onto the surface. Their optical properties were explored by measuring electroreflectance spectra as a function of electrode potential. Below their oxidation potential, no shift of the reflectance maximum was observed for Ag NCs. This can be explained by a low interfacial capacitance resulting from the impossibility for the electrolyte to penetrate into the hydrophobic layer created by the NCs dodecanethiol ligands. Conversely, a non-monotonous evolution was observed with the electrode potential for oleylamine capped Au NCs. This behavior is suggesting a less dense hydrophobic layer, allowing significant electrolyte penetration. Next, electroactive compounds were adsorbed on the the Au NCs assemblies and characterized by Raman spectroelectrochemistry. In the first system displaying a single electron transfer with no coupled chemical reaction, only the spectrum intensity changed, because oxidation generated a Raman resonant radical cation. The second study considered 4-nitrothiophenol, for which up to 6 electrons and 6 protons may be transferred. In this case, the nitro band disappeared upon reduction, and the spectrum displayed typical features of the formed 4-aminothiophenol.
ISSN:1572-6657
1873-2569
DOI:10.1016/j.jelechem.2020.114322