Electrochemical determination of benomyl using MWCNTs interspersed graphdiyne as enhanced electrocatalyst

Graphdiyne (GDY) has attracted a lot of interest in electrochemical sensing application with the advantages of a large conjugation system, porous structure, and high structure defects. Herein, to further improve the sensing effect of GDY, conductive MWCNTs were chosen as the signal accelerator. To get a stable composite material, polydopamine (PDA) was employed as connecting bridge between GDY and MWCNTs-NH2, where DA was firstly polymerized onto GDY, followed by covalently linking MWCNTs-NH2 with PDA through Michael-type reaction. The formed GDY@PDA/MWCNTs-NH2 composite was then explored as an electrochemical sensor for benomyl (Ben) determination. GDY assists the adsorption and accumulation of Ben molecules to the sensing surface, while MWCNTs-NH2 can enhance the electrical conductivity and electrocatalytic activity, all of which contributing to the significantly improved performance. The proposed sensor displays an obvious oxidation peak at 0.72 V (vs. Hg|Hg2Cl2) and reveals a wide linear range from 0.007 to 10.0 mu M and a low limit of detection (LOD) of 1.8 nM (S/N = 3) toward Ben detection. In addition, the sensor shows high stability, repeatability, reproducibility, and selectivity. The feasibility of this sensor was demonstrated by detecting Ben in apple and cucumber samples with a recovery of 94-106% and relative standard deviations (RSDs) less than 2.3% (n = 5).

Automated summary

Graphdiyne (GDY) has been widely applied in electrochemical sensing due to its large conjugation system, porous structure, and high structure defects. In this study, conductive MWCNTs were added to enhance the sensing effect of GDY. By using polydopamine (PDA) as a connecting bridge, a stable composite material GDY@PDA/MWCNTs-NH2 was formed and used as an electrochemical sensor for benomyl (Ben) detection. The sensor exhibited a wide linear range, low detection limit, high stability, repeatability, reproducibility, and selectivity, making it suitable for detecting Ben in apple and cucumber samples.