The interaction between Fe and Co dual active sites for promoting ultra-sensitive detection of trace paraquat

Paraquat is a highly toxic herbicide, and its residue in food poses a huge threat to human health. High-sensitivity detection of trace paraquat is crucial but challenging. Herein, we theoretically predicted that FeCo-MOF materials with Fe and Co dual active sites have potential interactions with paraquat. Moreover, a porous FeCo-MOF materials with Fe and Co dual active sites were in-suit constructed on the surface of foam nickel by self-assembly strategy, and used for the electrochemical detection of paraquat. The electrochemical detection results indicate that the prepared FeCo-MOF foam nickel electrode exhibited ultra-high detection sensitivity (113.85 μA nM −1  cm −2 ) and trace detection limit (0.16 nM) in a wide range of paraquat concentration (1.00 nM–5.00 mM). In addition, we successfully used this FeCo-MOF foam nickel electrode for the detection of paraquat in apples, human serum, and fresh tea leaves (detection recovery is 97.00 %–99.99 %). Furthermore, the density functional theory (DFT) and X-ray photoelectron spectroscopy (XPS) confirm that Fe and Co are active sites for detecting paraquat, and the interaction between Fe and Co promotes highly sensitive detection of trace paraquat. Therefore, this work provides strategies and comprehension for designing and modulating active sites at the microscopic level to improve sensitivity for detecting toxic pesticides.