Fe ₂ O ₃ Nanoisland‐Regulated Fe–Cu Dual‐Atom Nanozymes on Silica–Carbon Framework for NIR‐II‐Enhanced Tumor Catalytic Therapy

Dual‐atom nanozymes (DAzymes) offer tunable coordination environments and synergistic active sites, however, achieving multimodal therapy and biodegradability remains challenging. In this study, an “island‐sea” structured nanozyme (denoted as FeCu DA /FeO NC ‐Fe SA ) supported on a silica‐carbon hybrid framework is constructed via low‐temperature calcination of Fe/Cu‐doped silicate coating with dopamine‐Fe complex. Fe 2 O 3 nanoisland clusters (NCs) act as “islands”, while the surrounding silica/carbon matrix serves as the “sea”, enabling uniform dispersion of Fe–Cu dual‐atom active sites and facilitating magnetic resonance imaging (MRI)‐guided tumor therapy. Density functional theory calculations revealed that Fe 2 O 3 NCs modulated the d‐band center of the nanozyme, effectively lowering the reaction energy barrier and enhancing peroxidase‐like activity. The nanozyme exhibited a narrowed bandgap (1.14 eV), enabling efficient response to the second near‐infrared irradiation to generate reactive oxygen species for photodynamic therapy, together with a photothermal conversion efficiency of 41.2%. The nanozyme surface was further modified with hyaluronic acid to improve its biocompatibility and tumor‐targeting capability. Notably, the silica‐carbon framework further endows high catalytic activity and effective biodegradation in the tumor microenvironment, whereas the released Fe species serve as T 2 ‐weighted MRI contrast agents. This synthetic strategy may open up a robust route for the construction of high‐performance and biocompatible DAzymes for biomedical applications.