Synthesis And Modification Of Reduced Graphene Oxide Electrode Material Based On MoS₂ And CNTs Composites For Enhanced Electrochemical Properties

With the rapid development of people's living standards and improvement of health and safety,it is high important to detect the toxic and hazardous substances in production and living environments.In recent year,the electrochemical sensors based on novel sensitive materials have attracted great interests because of their high sensitivity,fast response,low detection limit,selectivity and anti-interference.In this thesis,the Au-MoS₂/rGO and Fe₂O₃-CNTs/rGO composites have been synthesized as the sensing materials,and the electrochemical performances of these sensors have been conducted on for the detection of toxic and harmful substances is realized.The detail works are as follows:In this paper,the Au-MoS₂/rGO and Fe₂O₃-CNTs/rGO composites were prepared by hydrothermal method and annealing reduction method,respectively.SEM,TEM,XRD,and XPS were used to characterize and analyze the microstructure,element composition and crystal structure of the composites.Meanwhile,electrochemical sensors based on composites were constructed and their electrochemical performance toward nitrite or hydrazine were studied.The main conclusions of this paper are summarized as follows:?1?The MoS₂/rGO composites were synthesized by hydrothermal method,and the characterization analysis indicated that the presence of rGO prevented the agglomeration of MoS₂ layer and improved the electron transport rate during the electrochemical reaction.Electrochemical detection shows that the electrochemical sensor based on MoS₂/rGO composite has a certain electrocatalytic effect on nitrite.In order to further improve the electrocatalytic effect of MoS₂/rGO composite toward nitrite,Au nanoparticles were grown on its surface by electrochemical deposition,and finally Au-MoS₂/rGO catalytically sensitive composites were successfully prepared.The experimental results dispalyed that the Au-MoS₂/rGO composite nanomaterials exhibited excellent electrochemical properties for nitrite,and the current response can be divided into two linear ranges:the sensitivity of the linear detection range at low concentration 0.2-2000?M can reach 0.934?A·?M^-1·cm^-2,and the sensitivity of the linear detection range at high concentration 2000-14000?M is 0.306?A·?M^-1·cm^-2,and the detection limit is 0.06 M.?2?The Fe₂O₃-CNTs/rGO composites were synthesized by oil bath hydrolysis reaction and annealing,and their morphology characterization and electrochemical properties were detected.It can be found that Fe₂O₃nanorods grow well on the CNTs backbones,and then the surface is wrapped with a thin layer of graphene sheet,this structure not only shortens the migration distance of particles,but also increases the electron transfer rate during the electrochemical reaction and increases the utilization rate of active materials.The electrochemical properties were investigated by cyclic voltammetry and amperometric titration,and the results show that the prepared sensor has higher sensitivity to nitrite(0.679?A·?M^-1·cm^-2),faster response time?3 s?,lower detection limit?0.08?M?,wide linear detection range?0.2¹3000?M?and strong interference capability.?3?Simultaneously,the hydrazine electrochemical sensor was successfully constructed based on Fe₂O₃-CNTs/rGO composite material,and its electrochemical performance for hydrazine detection was studied.The results showed that the Fe₂O₃-CNTs/rGO/GCE sensor showed a good electrocatalytic effect toward hydrazine,with a linear detection range of 0.3-3350?M,a sensitivity of 4.13?A·?M^-1·cm^-2,and a detection limit of 0.048?M.In addition,the sensor has excellent selectivity,reproducibility and stability.