Self‐assembled monolayers of inositol hexaphosphate on the roughened surface of an iron electrode: investigation by surface‐enhanced Raman scattering spectroscopy

Abstract

Inositol hexaphosphate (IP 6 ) molecules as an environmentally friendly inhibitor were self-assembled at a bare iron surface forming monolayers from a low concentration solution. Roughening of the iron surface by a special oxidation-reduction cycle makes it possible to obtain surface-enhanced Raman scattering (SERS) mapping spectra of the self-assembled monolayers (SAMs) of IP 6 . Using the recorded SERS spectra and quantum chemistry calculations for the vibrational modes of the IP 6 molecule with the PM3 method, the adsorption configurations of IP 6 SAMs formed at the roughened iron surface in bulk solutions under various pH conditions were deduced. At pH 5, the IP 6 molecules are assumed to be located at the surface via four coplanar phosphates to form SAMs, whereas at pH 11.27, value of the IP 6 solution it is assumed that only one phosphate is adsorbed on the iron surface. The results of electrochemical polarization measurements indicated that the inhibition efficiency of IP 6 SAMs formed at pH 5 was higher than at pH 11.27, which was related to their different interactions with the iron surface.

Recent Advances in linear and nonlinear Raman spectroscopy I

“…42 Further studies reporting enhancement of the Raman signal on electrode surfaces were: hydrogen peroxide electroreduction on a Pb-modified Au electrode, 43 electronic effects in SERS by liquid water, 44 ex situ and in situ SERS analyses of polybithiophene using roughened Ag and Cu electrodes and multilayer SERS-active systems, 45 self-assembled monolayers of inositol hexaphosphate on the roughened surface of an iron electrode, 46 potential dependent SERS profiles of sulfanilamide, 47 of sulfanilic acid, 48 and of orthanilic acid 49 on silver electrode. Organic monolayers or thin films formed on the electrode surfaces are of great interest for both fundamental and practical reasons, especially as an effective technique for surface modification and self-assembly.…”

Investigations of Triphenyl Phosphate and Bis-(2-ethylhexyl) Phosphate Self-Assembled Films on Iron Surface Using Electrochemical Methods, Fourier Transform Infrared Spectroscopy, and Molecular Simulations

“…Among the previous studies, compounds with the phosphoric functional group were considered to be one of the most effective chemicals for inhibiting the corrosion of iron. − Yang et al found that inositol hexaphosphate molecule (IP 6 ), which was an environmentally friendly inhibitor, self-assembled on a bare iron surface from a low concentration solution . The adsorption configuration of IP 6 SAMs was deduced by using surface-enhanced Raman scattering spectra and quantum chemistry calculation.…”