Electrochemical and anti-corrosion properties of octadecanethiol and benzotriazole binary self-assembled monolayers on copper

Graphical abstract: Self-assembled monolayers (SAMs) were fabricated on copper surface by immersing copper specimens in the aqueous solution containing octadecanethiol (C₁₈H₃₇-SH) and benzotriazole (BTA) only for five minutes, showing very good corrosion protection for copper. - Highlights: • A kind of self-assembly monolayers containing C₁₈H₃₇-SH and BTA was prepared. • The self-assembly monolayers show high corrosion inhibition performance to copper. • There is a synergy between heterocycle and sulfydryl groups on corrosion inhibition. • The properties of the binary SAMs are related to assembling sequence. - Abstract: Self-assembled monolayers based on octadecanethiol (C₁₈H₃₇-SH) and benzotriazole (BTA) (C₁₈H₃₇-SH&BTA SAMs) were fabricated on copper surface, showing effective corrosion protection for the substrate. The self-assembled monolayers (containing the composite SAMs and the SAMs based on single C₁₈H₃₇-SH or BTA) were characterized by surface enhanced Raman spectroscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and the results show that both C₁₈H₃₇-SH and BTA are successfully self-assembled on copper surface, forming compact SAMs. The anti-corrosion performance of the SAMs was studied by potentiodynamic polarization and electrochemical impedance spectroscopy. It is revealed that the anti-corrosion performance of the binary (C₁₈H₃₇-SH and BTA) composite SAMs is influenced by the assembling sequence. The C₁₈H₃₇-SH&BTA SAMs display the best anti-corrosion performance for copper with the highest charge transfer resistance of 5.0·10⁵ Ω cm².