Spectroscopic studies of the corrosion of model iron electrodes in carbonate and phosphate buffer solutions

LARROUMET, D., GREENFIELD, D., AKID, R. and YARWOOD, J. (2008). Spectroscopic studies of the corrosion of model iron electrodes in carbonate and phosphate buffer solutions. Journal of Raman Spectroscopy, 39 (12), 1740-1748.

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Link to published version:: 10.1002/jrs.2026

Abstract

We have extended our unenhanced (non-SERS) Raman spectroscopic investigations to include a study of the corrosion of an iron electrode in carbonate and phosphate buffer solutions. The measurements have been supported by electrochemical investigations (via cyclic voltammetry), enabling oxidation and reduction reactions to be systematically followed at variable applied potentials. In a carbonate buffer (pH = 9.4) the surface oxidation led to the formation of a 'green rust' (a hydrated hydroxy-carbonate), followed by the alpha- and beta-forms of FeOOH and an underlying magnetite layer formed on the cathodic (reduction) cycle. In a phosphate buffer (pH = 7.7) the surface was passivated by hydrated phosphates of iron [identified as FePO4 center dot xH(2)O and Fe-3(PO4)(2)center dot 8H(2)O]. The formation of oxides (Fe2O3 and Fe3O4) were inferred from voltammetry, but spectral identification was more difficult because of broad, ill-defined spectra. Despite the challenges of using unenhanced Raman spectroscopy, we believe that the effort was worthwhile, the reactions identified being more likely to be relevant to real electrochemical environments. Copyright (C) 2008 John Wiley & Sons, Ltd.

Item Type: Article
Research Institute, Centre or Group: Materials and Engineering Research Institute > Structural Materials and Integrity Research Centre > Centre for Corrosion Technology
Identification Number: 10.1002/jrs.2026
Depositing User: Ann Betterton
Date Deposited: 11 Feb 2010 15:41
Last Modified: 13 Sep 2010 14:40
URI: http://shura.shu.ac.uk/id/eprint/1075

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