C-ZIF7@Ag/EP Coating for Eco-Friendly Marine Protection: Near-Infrared-Responsive Self-Healing with High Antibiofouling Efficacy

Marine engineering facilities face the dual challenges of biofouling and material corrosion over extended periods. Traditional antifouling coatings struggle to meet environmental and long-term service requirements due to excessive heavy metal ion release or a lack of self-healing capabilities. This study designed and prepared an epoxy resin-based coating (C-ZIF7@Ag/EP) incorporating C-ZIF7@Ag nanocomposites. By synergistically leveraging photothermal effects and controlled release of bactericidal ions, the coating achieved highly efficient antifouling and self-healing functionality. Under 808-nm near-infrared irradiation (150 s to reach 132 °C at 1.5 W cm^-2), the coating rapidly heated up. The coating exhibited a reversible viscoelastic solid-liquid transformation, enabling effective healing of surface scratches upon near-infrared irradiation. Antibacterial tests demonstrated 99.1% and 99.4% kill rates against <i>Escherichia coli</i> and <i>Pseudomonas aeruginosa</i>, respectively, under near-infrared light. Marine biofouling tests confirmed significant inhibition of organism attachment, such as that by conchs. Furthermore, acidic environments (pH = 4-6) synergistically promoted the controlled release of Zn²⁺ and Ag⁺ when combined with photothermal stimulation. The release concentrations of Zn²⁺ and Ag⁺ after 30 days were 1.95 μg cm^-2 d^-1 and 0.06 μg cm^-2 d^-1, respectively, remaining within environmentally safe levels and posing no risk of marine pollution. Electrochemical impedance spectroscopy (EIS) results indicated that after 30 days of immersion in artificial seawater, the |Z|_{0.01 Hz} value of the C-ZIF7@Ag/EP coating remained at 2.48 × 10⁸ Ω cm². The C-ZIF7@Ag/EP coating developed in this study offers a strategy for creating eco-friendly, long-lasting, self-healing marine antifouling and anticorrosion materials, demonstrating significant engineering application value.