Adsorption and inhibition behavior of 3-chloro-6-mercaptopyridazine towards copper corrosion in sulfuric acid

In this work, a new anti-corrosion regent 3-chloro-6-mercaptopyridazine (CMP) for copper in 0.5 M H2SO4 solution is developed for the first time. Various electrochemical methods were applied to study the corrosion inhibition performance of CMP which was further confirmed through scanning electron microscope (SEM) and atomic force microscope (AFM). Electrochemical results show that CMP can have a good effect on the inhibition of the copper corrosion in H2SO4 solution under all testing temperature conditions. The highest inhibition efficiency of CMP is 97.4%, 95.1%, and 95.0% in 298 K, 303 K, and 308 K, respectively. It can be found that the corrosion inhibition effectiveness is negatively related to temperature and positively related to the concentration. In addition, the Langmuir isotherm adsorption model is suitable for the adsorption process of CMP on copper substrate, and the ΔG0ads value is less than − 40 kJ/mol. The experimental results show that the adsorption type between CMP and copper surface is chemical adsorption, further demonstrated by the N-Cu and S-Cu bonds in XPS. Finally, through quantum chemical calculation and molecular dynamics simulation, it have been further verified that the Cu(1 1 1) surface is in close contact with the CMP in a parallel manner, confirming its possessing good corrosion inhibition performance in sulfuric acid solution.