Detection of corrosion inhibition by dithiane self-assembled monolayers (SAMs) on copper

Metal corrosion leads to serious economic energy loss. It is urgent to develop high-efficiency and environmental protection corrosion inhibitors. By simple chemical synthesis, 2‑butyl‑1,3-dithiane (BD) and 2-heptyl-1,3-dithiane (HD) corrosion inhibitors were synthesized. These two molecules formed protective self-assembled monolayers (SAMs) on the copper surface in ethanol solution. The electrochemical tests and surface morphology tests suggested that the inhibition performance of BD was better than HD for copper in 0.5 M H2SO4 medium with the maximal inhibition efficiency of 99.6% for BD-SAMs and 98.6% for HD-SAMs, which may be due to the greater steric hindrance of HD. Certainly, the inhibition efficiency was also significantly influenced by concentration and self-assembly time. Compared with two self-assembled molecules, the hydrophobicity of the copper surface with BD layer was enhanced, resulting in the promotion of anti-corrosion efficiency. Additionally, XPS analysis reveals that the SAMs prevent copper corrosion by controlling the production of Cu2+, which is the decisive step in the corrosion process. Furthermore, quantum chemical calculation and molecular dynamics simulation provide evidence for the inhibition efficiency and the mechanism of the target molecules, and the conclusion is consistent with the experimental results.