Construction of a high-performance electrochemical sensor based on intrinsically conductive Co-HHTQ-MOF for...

The extensive use of imidacloprid (IMI) in modern agriculture has raised serious concerns regarding food safety and environmental health due to its toxic residue accumulation. Therefore, it is urgent to design a sensitive and rapid IMI detection sensor. In this study, a 2D conductive metal-organic framework cobalt-2,3,7,8,12,13-hexahydroxytricycloquinazoline-metal-organic framework (Co-HHTQ-MOF) was designed and fabricated using the π-d conjugation and π-π superposition interactions between metal ions and organic ligands in 2D layers. The successful formation of the material was confirmed through scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and Brunauer-Emmett-Teller (BET) analysis. The electrochemical behavior of the Co-HHTQ-MOF/GCE sensor was investigated using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Using differential pulse voltammetry (DPV), the sensor exhibited a linear response toward IMI in the linear range 0.4-30 nM, with a low limit of detection (LOD) of 0.086 nM (S/N = 3) and a high sensitivity of 0.120 µA nM^-1cm^- 2. The sensor also demonstrated excellent repeatability, strong anti-interference capabilities, and stability over 10 days. When applied to real samples of tomato, grape, and corn, recoveries ranged from 103.68% to 108.54%, confirming the sensor's strong potential for accurate pesticide residue monitoring in agricultural products.