Fe(OH) ₂ -Mediated Synthesis of Ultrathin Fe ₃ O ₄ Nanosheets Showing Enhanced Peroxidase-like Nanozyme Activity

The optimization of selective enzyme-like catalysis and the controlled generation of reactive oxygen species (ROS) remain central challenges in nanozyme research for catalytic and biomedical applications. Here we prepare ultrathin Fe 3 O 4 nanosheets via a polyol-assisted alkaline precipitation strategy, mediated by a layer-structured Fe(OH) 2 precursor. Electron microscopy shows a corrugated nanosheet architecture of atomic thickness, and electronic state analyses reveal a mixed-valence inverse spinel structure with electronic heterogeneity. Because of the ultrathin morphology, the Fe 3 O 4 nanosheets exhibit enhanced peroxidase-like activity, efficiently catalyzing H 2 O 2 -mediated TMB oxidation through surface-accessible Fe 2+ /Fe 3+ redox cycling. This work highlights morphology-driven regulation as an effective strategy for tuning nanozyme redox behaviors and ROS generation toward advanced catalytic and biomedical applications.