5,5′-dithiobis-(2-nitrobenzoic acid) self-assembled monolayer for corrosion inhibition of copper in sodium chloride solution

In this paper, 5,5′-Dithiobis-(2-nitrobenzoic acid) (DTNB) was used as an organic self-assembled monolayer on copper surface for the first time. The inhibition performance in 3.5 wt% NaCl solution was studied via electrochemical techniques, surface analysis methods and theoretical calculations. The influence of concentration on inhibition performance of DTNB was investigated by electrochemical impedance spectroscopy and potentiodynamic polarization. It is found that the inhibition efficiency of the self-assembled monolayer first increases and then decreases with the addition of DTNB, and the maximum inhibition efficiency is 92.4% at the DTNB concentration of 1 × 10-3 mol·L-1. The inhibition effect of DTNB was also evaluated by morphology observation of copper using scanning electron microscopy (SEM) and atomic force microscopy (AFM). Raman spectroscopy, X-ray photoelectron spectroscopy and quantum chemical calculations were utilized to determine that DTNB is well bound to copper surface through chemical bonds.