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Adsorption and Structure of Octadecanethiol on Zinc Surfaces As Probed by Sum Frequency Generation Spectroscopy, Imaging, and Electrochemical Techniques

Authors :
Hedberg, Jonas
Leygraf, Christofer
Cimatu, Katherine
Baldelli, Steven
Source :
The Journal of Physical Chemistry - Part C; November 2007, Vol. 111 Issue: 47 p17587-17596, 10p
Publication Year :
2007

Abstract

Octadecanethiol (ODT) adsorbed onto zinc has been studied with sum frequency generation (SFG), sum frequency generation imaging microscopy (SFG-IM), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), and electrical impedance spectroscopy (EIS) in order to investigate its corrosion protective ability and conformational ordering. SFG shows that ODT forms an ordered adsorbate on both reduced and oxidized zinc within short times after immersion in 1 mM ODT/ethanol solution. The corrosion protection, deduced by EIS, is also improved after immersion in the ODT solution. After longer immersion times, the corrosion protection decreases as well as the conformational order of the adsorbed ODT. Increasing the ODT concentration avoids this degradation with prolonged immersion time. The ODT is seen in the XPS spectra to adsorb to the reduced as well as the oxidized zinc by forming a Zn−S bond for both short and long immersion times. The SFG-IM completes the picture, showing a heterogeneous surface with areas corresponding to ordered ODT as well as disordered or uncovered regions. The density of adsorbed ODT after 24 h immersion time for both reduced and oxidized zinc was deduced from CV and was found to be approximately 6.7 × 10-9mol/cm2.

Details

Language :
English
ISSN :
19327447 and 19327455
Volume :
111
Issue :
47
Database :
Supplemental Index
Journal :
The Journal of Physical Chemistry - Part C
Publication Type :
Periodical
Accession number :
ejs13186349
Full Text :
https://doi.org/10.1021/jp075286+