Electrochemical Sensor Built on Graphene@Iron-Based Metal–Organic Frameworks for Simultaneous Detection of Cd2+ and Pb2+

The contamination of heavy metal ions (HMIs) in the environment poses a serious threat to health and safety. It is essential to efficiently and accurately detect multiple HMIs in environmental samples for water quality monitoring. In this work, a two-dimensional material composed of polyvinylpyrrolidone/graphene and iron-based metal–organic frameworks (PVP/GNs@Fe-MOF) was synthesized by ultrasonic method. This material combines the advantages of PVP/GNs and Fe-MOF, exhibiting enhanced conductivity, large specific surface area, and porosity, thus broadening the application potential of MOF and demonstrating excellent performance in electrochemical sensing. Using PVP/GNs@Fe-MOF as the electrode material, a simple electrochemical sensing platform was constructed for the simultaneous detection of Cd²⁺ and Pb²⁺. The results show good analytical performance with linear ranges of 0.030–1.0 μmol/L for Cd²⁺ and 3.0 nmol/L−1.0 μmol/L for Pb²⁺, and the limit of detection of 0.010 μmol/L and 1.0 nmol/L (S/N = 3), respectively. The rapid and sensitive simultaneous detection of Cd²⁺ and Pb²⁺ in real sample was also achieved.