Long-term superhydrophobic, antibacterial, and corrosion-resistant Ag-loaded LiAl-LDH composite coating grown in-situ on MAO coating

Abstract

This study successfully prepared long-term superhydrophobic, antibacterial, and corrosion-resistant lithium aluminum layered double hydroxide (LiAl-LDH) modified with 1H,1H,2H,2H-perfluorooctyltriethoxysilane (PFOTES) through a hydrothermal reaction. The LiAl-LDH was in situ grown on the micro-arc oxidation (MAO) film and loaded with Ag nanoparticles. The results showed that at a hydrothermal reaction temperature of 150 °C, LiAl-LDH effectively filled the microscopic defects of the MAO coating, significantly enhancing its hydrophobicity. After PFOTES treatment, the water contact angle remained above 150° even after 75 days of immersion in simulated seawater. Additionally, the introduction of Ag+ notably improved the antibacterial properties of the coating. Electrochemical tests indicated that the corrosion resistance of the coating increased with higher hydrothermal temperatures. The corrosion current density of the coating obtained at 150 °C was measured at 2.30 × 10−9 A∙cm−2, which is two orders of magnitude lower than that obtained at 100 °C. Following hydrophobic modification, the corrosion current density decreased further, and after 50 days of immersion in simulated seawater, the |Z|0.01Hz value remained above 108 Ω·cm2, demonstrating excellent corrosion resistance. This study provides important experimental and theoretical foundations for developing metal surface protective coatings with broad application prospects.