Polypyrrole-Modified Molybdenum Disulfide Nanocomposite Epoxy Coating Inhibits Corrosion of Mild Steel

The search for lightweight and low-cost anticorrosion coatings is particularly important in coastal environments with high salt and humidity. Graphene-based anticorrosion coatings are currently unable to provide long-lasting corrosion protection for metals because of their “corrosion-promoting activity”, and graphene-like materials, such as molybdenum disulfide (MoS2), are beginning to be anticipated its ability to protect against metals. This paper reported a simple method for preparing polypyrrole (PPy)-modified MoS2 nanomaterials from natural bulk MoS2. Their corrosion resistance behavior as fillers for epoxy (EP) resins was investigated in 3.5 wt.% NaCl solution. After the preparation of the MoS2 nanosheet dispersion by liquid-phase sonication using ethanol aqueous solution, the polypyrrole-coated molybdenum disulfide nanomaterials (MoS2@PPy) were directly obtained by adding pyrrole monomer to it in the presence of the initiator ammonium persulfate. Tafel polarization curves showed that the corrosion current of the MoS2@PPy/EP coating was 0.006 µA/cm2 after 15 days of immersion in 3.5 wt.% NaCl solution, much lower than that of pure EP coating (19.134 µA/cm2), effectively improving the anticorrosive properties of the coating. Overall, this study offered a practical method for the application of natural bulk MoS2 for corrosion protection.