Graphene–polypyrrole thin hybrid corrosion resistant coatings for copper

• Sealing defects in graphene with PPy improves the coatings corrosion resistance.
• Polypyrrole visualizes defects in graphene.
• UV light enhances corrosion of graphene coated copper.
• Polypyrrole prevents delamination of graphene.

New corrosion-resistant hybrid coatings based on graphene and polypyrrole were prepared and studied. A two-step process was used to fabricate the coatings. First, graphene was grown on a commercial copper foil by chemical vapor deposition (CVD) method. As the coating consisting only from graphene was imperfect, the defects were sealed with polypyrrole using electrodeposition. Corrosion resistance of copper, copper with CVD-graphene coating, and copper with CVD-graphene/polypyrrole hybrid coating were tested by immersion in salt water and also studied by open circuit potential measurements of the samples under ultraviolet radiation exposure, linear sweep voltammetry and cyclic voltammetry. The surfaces of the samples were also characterized by different microscopy and Raman spectroscopy methods. Although CVD graphene protected copper against corrosion in a certain extent, immersion tests revealed that the metal corrosion is mainly due to the graphene defects. The hybrid coatings showed much better anticorrosion performance.