Formation of inositol hexaphosphate monolayers at the copper surface from a Na-salt of phytic acid solution studied by in situ surface enhanced Raman scattering spectroscopy, Raman mapping and polarization measurement

Abstract

Inositol hexaphosphate (IP 6) was proposed as an environmentally friendly reagent to prevent metal surface from corrosion through a self-assembled monolayers (SAMs) method. In situ surface enhanced Raman scattering (SERS) spectroscopic investigations revealed that the self-assembling of IP 6 at the roughened copper surface in a Na-salt phytic acid solution took two steps involving firstly self-cleaning the surface and then forming IP 6 monolayers. The features of the IP 6 monolayers were evaluated by the time-dependent Raman spectroscopic measurement, Raman mapping and electrochemical polarization experiments. Based on the calculation results for vibration spectrum of IP 6 molecule with PM3 method, a model for IP 6 molecule adsorbed chemically on the roughened copper via two co-planar phosphate moieties was suggested. The copper surface with the IP 6 monolayers presents the inhibiting action in a 0.1 mol L −1 KC1 solution but the relative inhibition efficiency is of 41.2% because of the water co-adsorption.