Metal-center boosted adsorption capacity of bimetallic CeBi-metal organic frameworks for electrochemical monitoring of heavy metal ions in environment and food samples

It is significative to exploit an electrochemical sensor with high selectivity and sensitivity for monitoring Cd2+ and Pb2+. Metal-organic frameworks (MOFs) have attracted great attention due to their merits. Metal-centered regulation of MOFs is vital for boosting electrochemical performance. Herein, bimetallic CeBi-MOF supported polyaniline (CeBi-MOF/PANI) was fabricated by a solvothermal approach and an oxidative polymerization process. The obtained CeBi-MOF/PANI was subsequently exploited to modify a glassy carbon electrode (GCE) for quantification of Pb2+ and Cd2+. Density Functional Theory (DFT) denotes that the modulation of metal-center can adjust and boost the adsorption capacity, and CeBi-MOF(Bi) surface possesses higher adsorption energy for the analytes. Meanwhile, the introduction of PANI nanoparticles significantly enhances the electronic conductivity. Hence, greatly improved current is achieved on a CeBi-MOF/PANI/GCE. Low detection limits of 0.31 and 0.05 μg/L are gained for Pb2+ and Cd2+, respectively. Finally, the sensor was successfully employed in real samples with satisfactory recovery rates.