A high–selectivity electrochemical sensor based on magnetic multi-metal composite carbon material of CoFe2O4/Zn/Co@C for Pb2+ detection in water

Lead (Pb ²⁺ ) contamination in water poses severe threats to human health, necessitating rapid and sensitive detection methods. Herein, a magnetic CoFe ₂ O ₄ /Zn/Co@C composite was synthesized via a solvothermal method followed by pyrolysis of bimetallic Zn/Co-MOFs (derived from ZIF-67/8) at 950°C under N ₂ atmosphere. The composite integrates the high conductivity of porous carbon with the synergistic effects of Zn/Co bimetal sites (e.g., enhanced Pb ²⁺ adsorption capacity and accelerated electron transfer kinetics). Comprehensive characterization (XRD, SEM, TEM, VSM, BET) confirmed the successful formation of a nanostructured material with uniform metal dispersion, high surface area (475.46 m ² /g), and strong magnetism (saturation magnetization: 18.98 emu/g). When modified on a glassy carbon electrode (GCE), the sensor achieved a wide linear range (0.001–90 µM), an ultralow detection limit (1.3 nM, S/N = 3), and high sensitivity (36.44 µA·µM⁻¹·cm ^− 2 ), outperforming most reported MOF-derived sensors. Additionally, the sensor exhibited excellent selectivity (<5% interference), stability (98.3% response retention after 7 days), and reproducibility (RSD = 2.13%), with satisfactory recovery rates (99.5–103.4%) in real water samples. This work provides a promising strategy for designing magnetic MOF-derived composites for environmental monitoring.