Fabrication and characterization of polypyrrole coatings by embedding antimony modified SnO ₂ nanoparticles

Polypyrrole (PPy) coatings were successfully electrosynthesized on the carbon steel by embedding SnO ₂ and Sb-SnO ₂ nanoparticles (NPs). The associated structural, morphology, hydrophobic, physical properties, anti-corrosion and self-healing performance of these coatings were systematically studied by several tests. XRD results showed that SnO ₂ had a tetragonal rutile structure and the lattice parameters indicated that Sb ions were successful substituted into SnO ₂ lattice. The average size of SnO ₂ NPs was decreased by the incorporation of Sb-SnO ₂ NPs, which were found through TEM images. The contact angle test showed that the hydrophobic of PPy coatings was greatly enhanced by the incorporation of Sb-SnO ₂ NPs. SEM results revealed that Sb-SnO ₂ /PPy coating exhibited a more compact and uniform surface than SnO ₂ /PPy coating, hence the physical barrier effect was significantly strengthened. The electrochemical measurements confirmed the excellent anti-corrosion and self-healing ability of Sb-SnO ₂ /PPy coating for a long immersion time in HCl solution. The superior anti-corrosion performance of Sb-SnO ₂ /PPy coating was ascribed to the synergistic effects of the anodic protection combined with the self-healing effect, the excellent physical barrier effect with compact, smooth and hydrophobic coating surface as well as the formation of p-n junction with decreased charge transfer.