High-Strength Composite Coating Constructed by the Coordination of Metal–Organic Frameworks and Nanorods for Sustainable Corrosion and Biofouling Mitigation

Corrosion and biofouling are currently the biggest threats to marine engineering equipment, and how to design and prepare new multifunctional coatings still faces some challenges. In this work, the integrated anticorrosion and antibiofouling organic coatings possessing a high mechanical strength and good self-healing properties based on Co₃O₄ nanorods and nanoporous metal–organic framework ZIF-8 were successfully prepared. Results demonstrated that the prepared Co₃O₄/ZIF-8 and Co₃O₄/ZIF-8-SPT coatings, especially Co₃O₄/ZIF-8-SPT coatings, not only have high mechanical strength but possess good anticorrosion and antibiofouling properties. The fracture strength and toughness of Co₃O₄/ZIF-8-SPT coating increase by 46.7 and 64.2%, respectively, compared to the epoxy resin coating. The antibiofouling efficiencies of the prepared Co₃O₄/ZIF-8-SPT coating against Pseudomonas aeruginosa and Chlorella vulgaris, the typical biofouling organisms, have high values of 98.5 and 98.6%, respectively, and mussels and sea snails cannot adhere to the coating surface. Salt spray tests of 500 h demonstrate that Co₃O₄/ZIF-8-SPT coating possesses long-term corrosion resistance, and electrochemical impedance spectroscopy data confirm that Co₃O₄/ZIF-8-SPT coating also owns good stability of anticorrosion because of the slight increase in impedance values. Furthermore, the Co₃O₄/ZIF-8-SPT coating shows a good self-healing ability, and the impedance values at the position of the scratch line increase by approximately three times during 12 h.