Investigation of ZIF-L@g-C3N4-modified epoxy coatings for enhanced corrosion protection of carbon steel in marine environments

To address the limitations of conventional epoxy coatings—limited physical barrier function and lack of active protection in harsh marine environments—this study proposes a novel design strategy for a two‑dimensional/two‑dimensional (2D/2D) heterostructured nano‑filler. ZIF‑L crystals were directly grown on the surface of graphitic carbon nitride (g‑C₃N₄) via an in situ growth method, constructing a ZIF‑L@g‑C₃N₄ hybrid material that integrates efficient physical barrier properties with intelligent responsive functionality. The material not only extends the diffusion path of corrosive media through the layered structure of g‑C₃N₄, but also utilizes the controlled decomposition of ZIF‑L under corrosive micro‑environments to release Zn²⁺ and 2‑methylimidazole, achieving active self‑healing and chemical protection at coating defects. Systematic electrochemical and mechanical tests revealed that the epoxy coating incorporated with ZIF‑L@g‑C₃N₄ maintained a low‑frequency impedance modulus of 10⁸ Ω·cm² after 40 days of immersion in 3.5% NaCl solution, significantly outperforming pure epoxy and single‑component modified coatings. Moreover, the coating substrate adhesion strength increased to 3.723 MPa, demonstrating excellent interfacial bonding. This work not only develops a high‑performance anti‑corrosion coating with a synergistic “passive barrier‑active repair” dual mechanism, but also provides a new structural design strategy and technical pathway for designing next‑generation intelligent anti‑corrosion composite materials. • Combined 2D ZIF with g-C 3 N 4 to enhance epoxy resin's anti-corrosion performance. • 28-day immersion kept coating's low-frequency impedance near 10 8 Ω·cm 2 . • ZIF-L@g-C 3 N 4 boosts coating adhesion to 3.723 MPa, surpassing pure epoxy.