Defect-engineered Cu-CeO2 nanozymes with boosted haloperoxidase mimicry for marine antifouling efficacy at ultra-low dosage

Biofilm formation on material surfaces is a persistent challenge in aquatic environments, creating an urgent need for sustainable catalytic antimicrobial strategies. Although ceria nanozymes with haloperoxidase (HPO)-like activity have attracted increasing attention, their practical application is limited by the low density of surface Ce 3+ sites and oxygen vacancies. Herein, defect-engineered Cu-doped CeO 2 nanozymes were developed to enhance HPO-like catalytic activity and antibacterial performance. Cu incorporation regulated the Ce 4+ /Ce 3+ redox equilibrium and promoted oxygen-vacancy formation, resulting in enhanced catalytic activity, while controlled Cu 2+ release contributed to synergistic antibacterial effects. As a result, the optimized Cu-CeO 2 nanozymes achieved approximately 99% bacterial inactivation against E. coli and 97% inhibition against Bacillus sp. at a low nanoparticle concentration of 10 mg/L, demonstrating broad antibacterial activity against representative Gram-negative and Gram-positive bacteria. Combined experimental characterization and density functional theory calculations revealed the defect-mediated mechanism underlying the enhanced catalytic performance. This work provides a defect-engineering strategy for developing ceria-based nanozymes with enhanced catalytic antibacterial performance for potential catalytic antifouling applications.