Nanocavity Confining Platinum Nanoclusters Enhances Photocatalytic Two-Electron Oxygen Reduction for Wound Healing

Photocatalytic two-electron oxygen reduction reaction (ORR) toward H₂O₂ synthesis is a compelling approach for clinical antibacterial applications. Yet its selectivity is hampered by the competing four-electron ORR, which compromises both H₂O₂ generation kinetics and antibacterial efficiency. Herein, we report a new nanoscale confinement strategy for the controllable synthesis of covalent organic frameworks (COFs) confining isolated platinum nanoclusters (NCs) to enhance Pauling-type of O₂ adsorption to achieve two-electron oxygen reduction for efficient antibacterial therapy. The resulting Tfp-Db COFs@Pt NCs exhibits a significantly higher H₂O₂ formation kinetics (3.12 × 10-³ mol L^-1 h^-1) than Tfp-Db COFs@Pt nanoparticles (1.55 × 10^-3 mol L^-1 h^-1), with 2e^- ORR selectivity increased from 45.0% to 86.0%. Experimental and theoretical results reveal a two-step single electron oxygen reduction pathway for H₂O₂ photosynthesis over Tfp-Db COFs@Pt NCs. The Tfp-Db COFs@Pt NCs exhibits excellent sterilization efficiencies of 5.0 log₁₀CFU mL^-1 and 5.2 log₁₀CFU mL^-1 against S. aureus and E. coli, respectively, exceeding most reported materials. Furthermore, Tfp-Db COFs@Pt NCs facilitate the regeneration of infectious wounds, with the efficiency of nearly 100% on day 10, outperforming previously reported bionanomaterials. Collectively, this work presents a new strategy for regulating the Pauling-type of O₂ adsorption to enhance the photocatalytic H₂O₂ formation for wound healing application.