Preparation of a self-assembled monolayer on iron by the formation of a covalent bond between carbon and iron atoms

Tadashi Shimura, Kunitsugu Aramaki

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Abstract

A self-assembled monolayer (SAM) of toluene moiety CH3C6H4- was prepared on an iron electrode by electrochemical modification in a deaerated acetonitrile (AN) solution of p-toluenediazonium tetrafluoroborate CH3C6H4N2BF4 (TDFB). The protection of the modified electrode was examined by polarization measurements in an oxygenated 0.5 M NaCl solution after immersion in the solution for 1.5 and 4.0 h. The average values of protective efficiency, P for the films prepared by modification in the TDFB solution at -1.013 V/Ag/Ag+AN for the modification time, tm more than 5 min were fairly high, 78.1% and 53.6% at 1.5 and 4.0 h of the immersion time, t, respectively. However, X-ray photoelectron spectra of the iron surface modified with TDFB for 10 min revealed that the film thus prepared on iron was a polymer of the toluene moieties. A layer formed by the cathodic modification in the TDFB solution for 1 min seemed to be a monolayer of the toluene moiety, revealed by X-ray photoelectron spectra of the surface coated with the layer. The contact angle on the coated surface using a drop of water supported the formation of toluene SAM. The P values of the layer for iron corrosion in 0.5 M NaCl were 31.8% and 28.9% at 1.5 and 4.0 h of t, respectively, being a little higher than those of the toluenethiol CH3C6H4SH SAM. The higher values may be attributed to the formation of a strong covalent bond between carbon and iron atoms.

Original languageEnglish
Pages (from-to)3784-3801
Number of pages18
JournalCorrosion Science
Volume48
Issue number11
DOIs
Publication statusPublished - 2006 Nov 1

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Keywords

  • Covalent-bonded toluene moiety
  • Iron
  • Polarization
  • Self-assembled monolayer
  • XPS

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)
  • Materials Science(all)

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