Abstract: Coatings of marine equipment inevitably suffer from physical or chemical damage in service, together with biofouling from microbial attachment, leading to a shorter service life of them. Herein, a multifunctional corrosion-resistant coating with efficient photothermal self-healing and anti-biofouling performance was designed by using CuO/g-C₃N₄ (CuO/CN) S-scheme heterojunction filler in combination with polydimethylsiloxane (PDMS) as the coating matrix for achieving the effective protection of Q235 steel. The results of the electrochemical impedance spectroscopy (EIS) experiments indicate that the CuO/CN/PDMS composite coatings possessed excellent corrosion resistance, in which the impedance radius of optimal CuO/CN-1/PDMS composite coating could still remain 3.49 × 10⁹ Ω cm² after 60 d of immersion in seawater under sunlight irradiation. Meanwhile, the as-prepared CuO/CN/PDMS composite coating not only can be rapidly heated up under the Xenon lamp illumination to achieve complete self-repair of scratches within 45 min, but also exhibited excellent antimicrobial effects in the antifouling experiments. This study opens a new avenue for the development of g-C₃N₄-based multifunctional coatings and provides guidance for the development of the next generation of intelligent protective coatings.

Key words: g-C₃ N₄, Anti-corrosion, Self-healing, Anti-biofouling, S-scheme heterojunction