Modificaiton And Defect Engineering Of Layered MoS₂ And Its Sensing Performance To Benzimidazoles Agricultural Residues

Layered molybdenum disulfide（MoS₂）,a typical twodimensional（2D）layered transition metal dichalcogenidescomposed of stacking S–Mo–S layers by van der Waals interactions,has attracted particularly interest in electrochemical application owing to its earth-abundance and prominent electrocatalyticactivity.Nonetheless,the low density of active sites and poor electrochemical conductivity derived from pristine MoS₂restrict its further application.This fundamental issue can be settled via preparing metallic 1T phase MoS₂through phase engineering or decorating the MoS₂with high conducting materials.In this paper,MoS₂-based nanocomposites were successfully prepared through functional modification and defect manufacturing methods.The nanocomposites exhibited excellent electrical conductivity,high specific surface area,and excellent electrocatalytic activity for p-benzimidyl residues.By electrochemically modifying the glassy carbon electrode with this nanocomposite material,an electrochemical sensor was constructed and used for the detection of benzimidazole pesticide residues in various agricultural products and water samples,showing good sensor detection performance.The main research contents and results of this article are as follows:（1）Functionalized nanocomposites（MWCNTs-COOH/MoS₂）were successfully prepared using multi-walled carbon nanotubes（MWCNTs）for functional modification of2D MoS₂,and the materials were used to modify the glassy carbon electrode（GCE）to construct agricultural sensors for residual thiabendazole（TBZ）.The experimental results show that the sensor shows excellent sensing performance for TBZ,which is mainly due to the modification of MWCNTs can effectively improve the electrical conductivity and active specific surface area of MoS₂and produce a synergistic catalytic effect.Under the best experimental conditions,MWCNTs-COOH/MoS₂/GCE showed a wide linear range(0.2–1200.0μmol·L^-1),low detection limit(0.06μmol·L^-1),high anti-interference ability and high stability.In the analysis of pear,spinach and tap water samples,the recovery rate is in the range of 92.83%to 101.92%,the relative standard deviation（RSD）is less than 5%,and it is highly consistent with the detection results of high performance liquid chromatography（HPLC）.This work provides a fast,accurate and reliable detection method for pesticide residue TBZ in agricultural products.（2）Using ammonium molybdate as the molybdenum source and thiourea as the sulfur source and reducing agent,2D MoS₂was prepared by hydrothermal synthesis.Highly conductive graphene（Gr）is functionalized to modify MoS₂to produce the composite material Gr-MoS₂.SEM,TEM,AFM,XPS,XRD and Raman analysis showed that MoS₂was successfully prepared and Gr-MoS₂was successfully introduced into Gr.At 200℃,the MoS₂metal phase has a high proportion and is rich in defects,which can significantly enhance the conductivity and catalytic activity.Gr can further improve the conductivity and amplify the signal.An electrochemical sensor was constructed by modifying GCE with Gr-MoS₂,and carbendazim（CBZ）was detected by square wave voltammetry（SWV）.The results showed that Gr-MoS₂/GCE showed a wide linear range of carbendazim 0.05-120μmol·L^-1and a low detection limit of 0.025μmol·L^-1.The spiked recovery in lake water,cucumber juice and apple juice ranged from 93.65%to 106.58%,which matched the HPLC results.This work provides an accurate and reliable analysis method for CBZ residues in complex environments such as crops and lake water.