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 3,3′,5,5′-tetramethylbenzidine (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.