High-performance electrochemical sensor based on rGO/FeCo-MOF integrated with machine learning for simultaneous...

The simultaneous monitoring of cadmium (Cd²⁺) and lead (Pb²⁺) ions in environmental waters is crucial due to their high toxicity, persistence, and bioaccumulation potential. Herein, we developed a novel electrochemical sensor by modifying a glassy carbon electrode (GCE) with a bimetallic iron-cobalt metal-organic framework (FeCo-MOF) and reduced graphene oxide (rGO) for the sensitive detection of Cd²⁺ and Pb²⁺. Solvothermally synthesized FeCo-MOF displays enhanced intrinsic conductivity and a larger surface area than the monometallic counterparts. The incorporation of rGO promoted efficient electron transfer and enlarged the electrochemically active surface area, while also serving as a protective layer to improve electrode stability. The synergistic effects between FeCo-MOF and rGO facilitate the preconcentration of Cd²⁺ and Pb²⁺ ions and enhance electron transfer, resulting in excellent analytical performance with high sensitivity and good repeatability. For individual determination, the rGO/FeCo-MOF/GCE sensor achieves linear ranges of 1-200 μg/L (limit of detection (LOD) = 0.62 μg/L) for Cd²⁺ and 0.1-50 μg/L (LOD = 0.06 μg/L) for Pb²⁺. For simultaneous determination, mutual interference between Cd²⁺ and Pb²⁺ was systematically evaluated using eight machine learning models. The Extra Trees regressor provides the best predictive performance, with a Mean Absolute Error (MAE) of 0.080, a Root Mean Squared Error (RMSE) of 0.198, and an R-squared (R²) of 0.997. The integration of the rGO/FeCo-MOF/GCE sensor with the inverse Extra Trees model enables accurate quantification of Cd²⁺ and Pb²⁺ in real environmental water samples with relative errors below 8%. These results demonstrate the robustness and potential of the sensor for practical environmental monitoring applications.