Photothermal cyclic self-healing coating with extended corrosion resistance utilizing Ag2S@Ti3C2 heterojunction

Here, we developed a novel type of composite coating with excellent self-healing and anti-corrosion properties, activated by photothermally responsive nanofillers. The photothermal heterojunction Ag 2 S@Ti 3 C 2 was synthesized and functionalized with a silane coupling agent, and subsequently incorporated into an epoxy resin containing Diels-Alder (DA) bonds. It is found that the heterojunction enhances the light absorption, increases the number and lifetime of photogenerated electron-hole pairs, and facilitates the passage of photogenerated charges through the heterojunction interface, thereby reducing interface transfer resistance and releasing heat. Under irradiation with 808 nm near-infrared light, the photothermal effect of Silane-Ag 2 S@Ti 3 C 2 triggers molecular chain movement and dynamic DA bond reconstruction, thereby repairing scratches in the coating. Surface characterization and electrochemical tests indicate that the coating containing 1 wt% Silane-Ag 2 S@Ti 3 C 2 nanofillers exhibits significant self-healing and anti-corrosion properties. The self-healing rate of the coating approached nearly 96.00 %. After five self-healing cycles, the protective performance of the initial immersion stage was effectively restored, the self-healing rate remained at about 90.00 %. Even after 60 d of immersion, the low-frequency impedance modulus remained above 10 8 Ω·cm 2 . This study presents a novel strategy for the development of multi-cycle self-healing coatings utilizing photothermal effects.