Enhanced corrosion and UV resistance of double-layer structural epoxy coatings reinforced with graphene oxide/carbon nanotubes hybrids

Corrosion and UV degradation are among the primary threats to the long-term durability of epoxy coatings in outdoor applications. This study introduces a double-layer composite coating system comprising a silane sol-gel bottom layer to enhance the adhesion strength and an epoxy top layer loaded with functionalized graphene oxide@carbon nanotubes nanohybrids (F-GO@CNTs). This configuration imparts multifunctional properties including superior anti-corrosion, anti-UV, and mechanical performance. The Ep/F-GO@CNTs nanocomposite coating exhibits exceptional adhesion strength (8.8 MPa), high tensile strength (26.1 MPa), and outstanding corrosion resistance with an impedance of 5.49 × 10⁸ Ω.cm² which is two orders of magnitude higher than that of the pristine epoxy coating after 40 days of immersion in the sodium chloride solution. After 240 h of UV irradiation, the Ep/F-GO@CNTs coating shows minimal photodegradation and retains excellent comprehensive performance even under combined UV and corrosive exposure. This study provides a promising strategy toward developing durable protective coatings for outdoor applications.