Morphology-dictated H₂O₂ activation thresholds in cerium oxide nanozymes: Implications for antibacterial kinetics

The proliferation of antimicrobial resistance necessitates the development of novel antibacterial strategies. A primary challenge in nanozyme catalysis as antimicrobial is achieving high efficacy at the low oxidant concentrations found in natural environments. Here, we report the morphology-dependent antibacterial kinetics of 25 nm (nanopolyhedral) and 50 nm (faceted) cerium oxide nanozymes. While 25 nm nanozymes required millimolar H₂O₂ levels for significant activity, the well-defined {111} facets of the 50 nm nanozymes enabled a profound, bromide-mediated activation. Critically, this system achieved ∼80 % inhibition of Escherichia coli at an environmentally relevant H₂O₂ concentration of 400 nM, driven by a highly efficient haloperoxidase-like mechanism. This work establishes a clear structure-activity relationship where facet engineering unlocks potent nanozyme catalysis at ultra-low oxidant levels, presenting a direct pathway for sustainable antifouling coatings that leverage ambient aquatic chemistry.