Bionic engineering of COFs/g-C3N4 heterojunctions-enhanced poly-schiff base self-renewing coatings toward long-lasting anti-biofouling via boosted photocatalytic antibacterial activity

Solar-powered photocatalysis offers a sustainable anti-biofouling strategy free of chemical release and pollution. However, practical application in anti-fouling coatings faces inherent limitations, including low photocatalyst utilization, poor long-term stability, and insufficient exposure of the active site. Herein, a COF/g-C 3 N 4 heterojunction photocatalyst with enhanced light response and utilization is prepared by in situ growth of hollow tubular 1D-COF on a flake-like 2D g-C 3 N 4 surface. Inspired by biological molting, the heterojunction is further integrated with a degradable poly-Schiff base polymer (DSP) to fabricate a hybrid anti-fouling coating (D-COF/CN x ) that exhibits both biofouling-release and photocatalytic bactericidal activity. Leveraging a “water-triggered and reactive oxygen species (ROS)-responsive” dual degradation mechanism, the coating realizes desirable self-renewal and sustained exposure of photocatalytic active sites. Exposed COF/g-C 3 N 4 efficiently facilitates the separation and transfer of photogenerated charge carriers, boosting the bactericidal ROS yield by 1.99 to 2.61 folds compared to pristine g-C 3 N 4 and COF-1. Under the synergistic effect of photocatalytic sterilization and biofouling release, the coating achieves a nearly 100 % fouling-free surface at an ultra-low loading of 5% under high-biofouling conditions (10 8 to 10 9 CFU mL –1 ), thereby markedly reducing bacterial/microalgal adhesion and biofilm formation. After prolonged service, it retains excellent cyclic antibacterial stability and mechanical durability, providing novel insights for developing high-performance and versatile photocatalytic coatings with long-lasting biofouling resistance. Inspired by animal skin self-renewal, a self-renewing photocatalytic hybrid coating (D-COF/CN x ) integrates COF/g-C 3 N 4 heterojunction into a water-triggered degradable polymer matrix. This innovative structure enables a synergistic antifouling mechanism, combining highly efficient photocatalytic sterilization with dynamic surface self-renewal for fouling removal. The coating demonstrates nearly 100 % anti-fouling efficiency even under ultra-low photocatalyst loading (5 wt%) and high-biofouling conditions (10 8 –10 9 CFU/mL). • A 1D/2D photocatalytic heterojunction was efficiently constructed by in situ growth of hollow tubular COFs on flake-like g-C 3 N 4 . • The regulated IEF and CTC significantly enhance the separation and migration of photogenerated carriers. • An innovative photocatalytic self-renewal synergistic strategy enables sufficient and sustained exposure of photocatalytic active site. • D-COF/CN x achieves nearly 100 % antifouling performance even under low photocatalyst loadings and high-biofouling conditions. • The high-efficiency synergistic antibacterial mechanism of D-COF/CN x is elucidated.