Fabrication And Application Of Electrochemical Sensors Based On Molybdenum Disulflde Nanocomposites

MoS2 materials have received increasing attention, which is extensively applied in many fields such as catalysts, supercapacitors and optical device. In this paper, the electrochemical sensors were fabricated by using carbon material as the base electrode, graphene-like MoS2 material and composite nanomaterials as modifier materials. The MoS2 and nanocoposites were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) etc. Then, the MoS2 and nanocomposites were used for the fabrication of the electrochemical sensors by electrochemical technique. The main contents of this paper have been described as follows:The GR/MoS2 nanocomposites were synthesized by hydrothermal method using graphene oxide (GO) as precursor. The crystal structure and surface morphology of GR/MoS2 were characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (SEM).Based on GR/MoS2,an electrochemical sensor was constructed for the detection of residual pesticide carbendazim (CBZ) in Chinese wolfberry. The detection limit (LOD, S/N=3) is 4.6×10-9 mol·L-1.The MoS2 nanomaterials were prepared by hydrothermal method, and the crystal structure and surface morphology of MoS2 were characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (SEM). AuNPs were deposited on the surface of MoS2 modified graphite electrode (CPE) by constant potential deposition. Electrochemical sensors were constructed based on AuNPs/MoS2. Electrochemical Response Signals of Carbendazim (CBZ)was studied on the AUNPs/MoS2/CPE. The results show that AUNPS/MoS2/CPE has a significant effect on the electrochemical oxidation of CBZ. The detection limit for CBZ (LOD, S/N=3) is 8.5×10-8 mol·L-1. Based on this, a new electrochemical quantitative method for detection of CBZ was established, which could be applied to the detection of pesticide residues in Chinese wolfberry in real life.The molybdenum disulfide quantum dots (MoS2 QDs) were prepared by hydrothermal method. The pralidoxime iodide (PAM) was deposited on the surface of MoS2 QDs modified graphite electrode (CPE) by potentiostatic deposition method. The electrochemical sensor was successfully constructed based on PAM/MoS2 QDs. The surface morphology and elemental composition of each electrode were characterized by field emission scanning electron microscopy(SEM) and X - ray photoelectron spectroscopy (XPS). The sensor was applied to the direct and sensitive detection of organophosphorus pesticides (OPs). The results show that the excellent electrocatalytic activity of MoS2QDs and the specific binding of OPs and PAM have a significant effect on the electrochemical signal. According to the relationship between the change of electrochemical signal (AI) and concentration before and after adding OPs, a method for detection of OPs was established. The detection for OPs limit (LOD,S/N=3) was 5.3×10-11 mol·L-1 for OPs.Carbon quantum dots (CQDs) were prepared by hydrothermal method and the CQDs/MoS2 nanocomposites were synthesized by aqueous exfoliation method. The acetylcholinesterase biosensor based on the nanocomposites was constructed for the detection of organophosphorus pesticides (OPs). The results show that the biosensor combines the advantages of good biocompatibility of CQDs and the specific surface area and high electron transport properties of MoS2 nanomaterials,providing a good binding interface for acetylcholinesterase,using AChE inhibitor' OPs and reactivation agent PAM to improve the detection sensitivity.According to the relationship between the change of the electrochemical signal (AI) and its concentration after adding OPs and PAM respectively, the sensitive detection of OPs was carried out. The detection limit (LOD, S/N=3) is 4.7×10-11 mol·L-1,. Thus, a new electrochemical quantitative detection method for OPs was established.