Corrosion inhibition of copper in hydrochloric acid by coverage with trithiocyanuric acid self-assembled monolayers

Abstract

The corrosion inhibition properties of trithiocyanuric acid (TTCA) self-assembled monolayers (SAMs) on copper surfaces in hydrochloric acid have been investigated by electrochemical impedance spectroscopy, potentiodynamic polarisation and cyclic voltammetry methods. These results show that TTCA SAMs could keep the long term stability and provide a better corrosion protection for copper in acidic solution. The high quality SAMs depend mainly on the TTCA concentration and suitable self-assembly time. Fourier transform infrared spectroscopy, contact angle and SEM measurements reveal that TTCA is liable to interact with copper forming SAMs and produces a hydrophilic surface with an orderly layer structure. The adsorption behaviour of TTCA follows the Langmuir isotherm. Quantum chemical calculations show that the sulphur and nitrogen atoms act as the main active sites, and the small energy gap ΔE between the highest occupied molecular orbital and the lowest unoccupied molecular orbital and the low dipole moment μ favour the adsorption of TTCA on the copper surface.