Bimetallic FeZr-MOF with enhanced peroxidase activity via Fe-O-Zr bridging electronic synergistic effects: a three-channel sensor for organophosphorus pesticide recognition.

Organophosphorus pesticides present a notable risk to public health, making it essential to develop swift and dependable analytical techniques for food safety, yet conventional single-channel colorimetric sensors face great challenges in discriminating multiple structurally similar pesticides with high accuracy. To address these issues, a Fe-Zr bimetallic metal-organic framework nanozyme with prominently enhanced peroxidase activity was synthesized via a one-step solvothermal method. The intermetallic electron transfer through Fe-O-Zr bridges accelerates the reversible Fe3+/Fe2+ redox cycle; with a Michaelis-Menten constant (Km) of 0.11 mM for H2O2 and a maximum reaction rate (Vmax) of 9.95 × 10-8 M s-1, its catalytic efficiency outperforms monometallic analogues and the majority of previously reported MOF-based nanozymes. On this basis, a three-channel sensor array integrating absorbance, smartphone-based RGB colorimetric and photothermal signals was constructed, coupled with principal component analysis (PCA) and hierarchical cluster analysis (HCA) for chemometric pattern recognition. The sensor works effectively over a wide concentration range (5-200 μM), with excellent interference resistance and satisfactory recoveries (94.2%-107.4%) in real samples. Most importantly, the Fe-O-Zr bridging synergistic strategy offers a new approach to enhance MOF peroxidase activity, while the multi-channel architecture mitigates the limitation of single-channel sensors in differentiating similar pesticides, supporting reliable on-site food safety and environmental monitoring.