A Cu-MOFs@MnO2 nanocomposite-based ratiometric electrochemical sensor for simultaneous detection of Pb2+ and Hg2+

The development of reliable sensing platforms for the simultaneous detection of multiple heavy metal ions has remained challenging in environmental monitoring. Herein, a novel ratiometric electrochemical sensor was developed using a Cu-MOFs@MnO 2 NSs composite for the simultaneous quantification of Pb 2+ and Hg 2+ . The composite was synthesized through a facile approach and functionalized onto a screen-printed carbon electrode (SPCE) to establish an efficient sensing interface. This design capitalized on the synergistic properties of both components: MnO 2 nanosheets provided abundant surface hydroxyl groups and enhanced electrical conductivity, while Cu-MOFs contributed a large specific surface area with multiple binding sites for metal ion enrichment. Significantly, the incorporated Cu-MOFs functioned as an internal reference, delivering a stable built-in signal for ratiometric analysis. The developed sensor achieved impressive detection limits of 22.69 nmol/L for Pb 2+ and 30.07 nmol/L for Hg 2+ , while maintaining high selectivity and reproducibility in complex matrices. This study not only established a reliable platform for the accurate detection of Pb 2+ and Hg 2+ but also promoted the adoption of ratiometric strategies in electrochemical sensing to support environmental protection and public health security.