Issue 10, 2010

SERS and DFT study of water on metal cathodes of silver, gold and platinum nanoparticles

Abstract

The observed surface-enhanced Raman scattering (SERS) spectra of water adsorbed on metal film electrodes of silver, gold, and platinum nanoparticles were used to infer interfacial water structures on the basis of the change of the electrochemical vibrational Stark tuning rates and the relative Raman intensity of the stretching and bending modes. To explain the increase of the relative Raman intensity ratio of the bending and stretching vibrations at the very negative potential region, density functional theory calculations provide the conceptual model. The specific enhancement effect for the bending mode was closely associated with the water adsorption structure in a hydrogen bonded configuration through its H-end binding to surface sites with large polarizability due to strong cathodic polarization. The present results allow us to propose that interfacial water molecules exist on these metal cathodes with different hydrogen bonding interactions, i.e., the HO–H⋯H–Pt dihydrogen bond for platinum and the HO–H⋯Ag(Au) for silver and gold. This dihydrogen bonding configuration on platinum is further supported from observation of the Pt–H stretching band. Furthermore, the influences of the pH effect on SERS intensity and vibrational Stark effect on the gold electrode indicate that the O–H stretching SERS signals are enhanced in the alkaline solutions because of the hydrated hydroxide surface species adsorbed on the gold cathode.

Graphical abstract: SERS and DFT study of water on metal cathodes of silver, gold and platinum nanoparticles

Article information

Article type
Paper
Submitted
16 Sep 2009
Accepted
23 Dec 2009
First published
26 Jan 2010

Phys. Chem. Chem. Phys., 2010,12, 2493-2502

SERS and DFT study of water on metal cathodes of silver, gold and platinum nanoparticles

J. Li, Y. Huang, S. Duan, R. Pang, D. Wu, B. Ren, X. Xu and Z. Tian, Phys. Chem. Chem. Phys., 2010, 12, 2493 DOI: 10.1039/B919266B

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