A comparative electrochemical study of electrosorbed 2- and 4-mercaptopyridines and their application as corrosion inhibitors at C60 steel

Abstract

The electrochemistry of self-assembled monolayers (SAMs) prepared from 2-mercapto-pyridine (2 Mpy) and 4-mercaptopyridine (4 Mpy) dissolved in either water or an aqueous solution of 0-1 M H2SO4 on a polycrystalline gold electrode has been investigated in an aqueous electrolyte solution (0-5 M H2SO4) using cyclic voltammetry. Results suggest that 2 Mpy is adsorbed more strongly than 4 Mpy due to the formation of a S-Au-N chelate. The under-and over-potential deposition of copper from an aqueous solution of 0-1 M sulphuric acid is inhibited in the presence of these SAMs suggesting strong interactions between these adsorbates and the gold surface. A copper adlayer was partially displaced by adsorbing 2 Mpy and 4 Mpy. The inhibition effect of these SAMs on the corrosion of C60 steel has been investigated using electrochemical impedance measurements (EIM) in an aqueous 3-5 wt% NaCl solution. The polarization resistance and the inhibition efficiency were calculated. 2 Mpy has higher inhibition efficiency than 4 Mpy. © Indian Academy of Sciences.