Redox-Mediated Stabilization of Ultrasmall Au25 Nanoclusters in Amine-Functionalized MOF for Robust Photocatalytic Antibacterial Applications
Noble metal nanoclusters (MNCs) possess atomically precise structures and tunable compositions, yet their practical deployment is constrained by rapid oxidation-induced structural degradation and ligand detachment, leading to aggregation during storage and catalysis. This study introduces a redox-mediated stabilization strategy by integrating ultrasmall Au25 nanoclusters with amine-functionalized UiO-66-NH2. The uniformly dispersed amine groups act as reductive reagents, suppressing Au oxidation while reinforcing thiol-terminated ligand anchoring via dynamic coordination. This dual stabilization preserves the initial ultrasmall size and structural integrity of Au25 NCs under ambient storage and light irradiation. The engineered type-II heterojunction between Au25 NCs and UiO-66-NH2 enhances visible-light harvesting and charge separation, enabling efficient O2 activation to reactive oxygen species (ROS). The Au25/UiO-66-NH2 composites achieve 99.999% bacterial inactivation against Escherichia coli within 40 min under visible light, retaining high efficacy after five reuse cycles. Integration into wearable fabrics demonstrates potential for continuous antibacterial protection. This work establishes amine-functionalized MOFs as universal redox-active supports for stabilizing metastable MNCs, offering a versatile platform for durable photocatalytic systems in environmental and biomedical applications.