Cu-Fe Oxide Nanozymes with Enhanced Peroxidase-like Activity for Sensitive H2O2 Colorimetric Detection

Hydrogen peroxide (H ₂ O ₂ ) is a key reactive oxygen species involved in physiological regulation and pathological processes, and its accurate quantification is essential for bioanalysis and disease-related studies. Herein, we report the synthesis of a series of Cu-Fe oxide nanozymes via a simple antisolvent crystallization strategy and systematically investigate their peroxidase-like catalytic activity toward colorimetric H ₂ O ₂ detection. By tuning the Cu/Fe molar ratio, the catalytic activity of the nanozymes can be effectively regulated, with Cu ₂ FeO _x exhibiting the highest peroxidase-like activity toward TMB oxidation in the presence of H ₂ O ₂ under acidic conditions and enabling sensitive colorimetric detection of H ₂ O ₂ over a linear range of 10–200 µM with a detection limit of 0.572 µM. Furthermore, the proposed sensing platform demonstrates satisfactory selectivity and reproducibility, and is successfully applied to the determination of H ₂ O ₂ released into cell culture supernatants after chemical stimulation. This work highlights the potential of composition‑regulated Cu-Fe oxide nanozymes as robust artificial enzymes for colorimetric H ₂ O ₂ sensing and provides insights into their application in bioanalytical systems.