Ultra-sensitive electrochemical sensors through self-assembled MOF composites for the simultaneous detection of multiple heavy metal ions in food samples.

Using an assemble-able MOF material, we successfully constructed an ultra-sensitive electrochemical sensor based on BiCuO@Al-MOF@UiO-67 nanocomposite material, in order to investigate the adsorption properties of the BiCuO@Al-MOF@UiO-67 functional material on the heavy metal ion. The Cd, Cu, Pb and Hg can be detected at the same time. Selective recognition and enrichment of various metal ions on different substrates can be achieved through the assembly of a large number of Al-MOF and UiO-67-MOF nanomaterial composites with small particle sizes on the BiCuO surface. Based on this, a new type of sensor is researched and prepared, which has been shown to have good stability and reproducibility. Due to its unique assembly structure, large active surface area, excellent adsorption capacity, and high electrical conductivity, BiCuO@Al-MOF@UiO-67 presents outstanding performance. In addition, the sensor also exhibits excellent electrocatalytic redox capacity and high selectivity. The adsorption capacity of Cd, Cu, Pb and Hg is also significantly improved under the action of the sensor electrode, however, this is not the case. The limits of detection for Cd, Cu, Pb and Hg were found to be 0.02 pM, 0.032 pM, 0.018 pM and 0.041 pM, respectively. In order to investigate the detection mechanism of Cd, Cu, Pb and Hg was adsorption properties as well as electrochemical accumulation of BiCuO@Al-MOF@UiO-67 on the metal atoms were investigated. This method has been successfully applied to samples of rice, sorghum, maize, milk, honey, and tea, and has enabled the simultaneous detection of Cd, Cu, Pb and Hg, which is of significant practical value.