Hydrothermal engineering of triple-scale corrosion resistance: Structural barrier, oxygen vacancy, and surface functionalization in Ce-NiCo-LDH coatings

We report a hydrothermal engineering strategy to synergistically regulate structural barriers, oxygen vacancy-driven redox cycling, and surface functionalization in Ce-NiCo-LDH coatings for ultralong corrosion protection. Vertically aligned LDH nanosheets constructed a tortuous labyrinth barrier to physically impede corrosive species penetration. Oxygen vacancies acted as electron reservoirs to drive Ce 3+ /Ce 4+ redox cycling, enabling dynamic passivation repair via preferential Ce 4+  → Ce 3+ reduction at vacancy sites. Surface functionalization further enhanced protection through two independent pathways: CTAB induced interlocked fibrous nanostructures for mechanical reinforcement, while PFDT grafting formed a fluorine-rich hydrophobic barrier through C-F dipole interactions. EIS characterization demonstrated a 3.6-fold enhancement in charge transfer resistance (Rct = 5.1 × 10 5 Ω·cm 2 ) for the sequentially hydrothermally processed Ce-NiCo-LDHs compared to their single-step counterparts (1.4 × 10 5 Ω·cm 2 ). The CTAB-modified coating achieved 99.0 % inhibition efficiency, while PFDT modification provided long-term hydrophobicity. This triple-scale synergy-structural obstruction, redox-mediated self-healing, and surface engineering-provides a universal framework for designing advanced protective coatings.