Study On Synthesis Of Sensing Materials Based On Reduced Graphene Oxide And Electrochemical Detection To Organic Compounds

Nowadays,people pay more attention to their living environment and health along with the improvement of environmental protection consciousness and health consciousness.As common materials that exist in everywhere,organic compounds relate to the environmental problem and health.The detection of organic contaminants can be early warning of the excessive emissions of pollution sources in our environment.The detection of organic compounds related to human body health can realize the disease prevention.The detection of organic compounds in our food can prevent the food safety problems.Hence,the detection of organic compounds is of great significance.It is worth mentioning that electrochemical technique for organic compounds detection offers an opportunity for portable,cheap and rapid methodology.Nowadays,a variety of materials have been developed for electrochemical detection of organic compounds.Generally,the working electrodes that are modified by sensing materials directly decide the performance of electrochemical detection.Therefore,the sensing materials are most important for electrochemical detection of organic compounds.The popularity of graphene is due to the fact that its honeycomb lattice molecular structure leads to remarkable physical and chemical properties,such as high surface area,high thermal and electrical conductivity,high chemical stability.The working electrodes are modified by graphene,which can effectively improve the electronic transmission performance in the process of electrochemical detection.Furthermore,graphene can be used as auxiliary materials to load nanocatalyst,which can not only be a good conductive network but also prevent nanocatalyst conglomerating.The graphene-based sensing materials have been extensively developed in recent years.However,some problems exist in the preparation process of graphene-based working electrodes.For example,the graphene tends to form an irreversible aggregation because of the intensive ?-? interaction among the graphene layers during the chemical reaction process,which also obstructs the uniformity of materials and subsequent the performance of electrochemical detection.In this thesis,some reduced graphene oxide-based sensing materials have been prepared by using different synthetic methods in order to overcome those problems.The sensing performance of reduced graphene oxide-based materials have been also investigated in our works.The main research contents are as follows:(1)Ag nanoparticles-reduced graphene oxide-carbon nanotube(Ag NPs-r GO-CNT)hybrids have been synthesized by wet-chemical method.Subsequently,the material component and morphological structure of Ag NPs-r GO-CNT have been investigated by raman spectrum,X-ray diffraction(XRD),transmission electron microscope(TEM),thermogravimetric analysis and so on.In the study of electrochemical detection,Ag NPs-r GO-CNT hybrids have been used as the sensing material to modify glassy carbon electrode(GCE).Then Ag NPs-r GO-CNT/GCE has been used as working electrode to establish the electrochemical sensor.Compared with Ag NPs/GCE and Ag NPs-r GO/GCE,Ag NPs-r GO-CNT/GCE exhibits better sensing performance.The effect of supporting electrolyte p H and scan rate on the electrochemical detection performance of Ag NPsr GO-CNT/GCE have been investigated by cyclic voltammetry.The electrochemical detection performance,such as linear detection range,detection limit and selectivity,have been investigated by I-t curve.All these observations indicate Ag NPs-r GO-CNT hybrids have excellent performance for electrochemical detection of hydrogen peroxide.(2)Reduced graphene oxide-carbon nanotube(r GO-CNT)hybrids have been synthesized by electrodeposition on the surface of indium tin oxide(ITO).Subsequently,the material component and morphological structure of r GO-CNT have been investigated by X-ray photoelectron spectroscopy(XPS)and scanning electron microscope(SEM).The electrodeposition process of r GO-CNT hybrids has been investigated by cyclic voltammetry.The effect of r GO-CNT thickness and CNT content on the electrochemical activity of r GO-CNT have been investigated by using the electrocatalytic reaction between Fe(CN)64-and Fe(CN)63-in potassium ferricyanide solution.In the study of electrochemical detection,the electrochemical sensor has been established by direct using r GO-CNT/ITO as working electrode.Compared with bare ITO,r GO/ITO and CNT/ITO electrodes,the r GO-CNT/ITO electrode exhibits excellent sensing performance for electrochemical detection of ascorbic acid(AA),dopamine(DA)and uric acid(UA),leading to a high-performance electrochemical sensor for simultaneous detection of AA,DA and UA.The effect of scan rate on the electrochemical detection performance of r GO-CNT/ITO has been investigated by cyclic voltammetry.The linear detection range,detection limit and selectivity of r GO-CNT/ITO have been investigated by differential pulse voltammetry.All these observations indicate r GO-CNT/ITO have excellent performance for electrochemical detection of AA,DA and UA.(3)A two-step electrodepostion method was carried out for in-situ growth of Ag metal-reduced graphene oxide-carbon nanotube on indium tin oxide(Ag-r GO-CNT/ITO).Subsequently,the material component and morphological structure of Ag-r GO-CNT have been investigated by XRD,XPS and SEM.In the study of electrochemical detection,the electrochemical sensor has been established by direct using Ag-r GO-CNT/ITO as working electrode.Compared with r GO/ITO,r GO-CNT/ITO and Ag-r GO/ITO electrodes,the Ag-r GO-CNT/ITO electrode exhibits excellent sensing performance for electrochemical detection of hydrogen peroxide.The electrochemical active surface areas of Ag-r GO-CNT/ITO have been investigated by cyclic voltammetry.The linear detection range,detection limit and selectivity of Ag-r GO-CNT/ITO have been investigated by I-t curve.All these observations indicate Ag-r GO-CNT/ITO have excellent performance for electrochemical detection of hydrogen peroxide.(4)N-doped carbon film(NC)has been successfully prepared by the pyrolysis of ZIF-8.According to the specific design,Au nanoparticles(Au NPs)have been coated by NC,which can restrain the conglomerating,mobile and loss of Au NPs.Subsequently,the material component and morphological structure of obtained N-doped carbon film-immobilized Au nanoparticles coated Zn O jungle on indium tin oxide(Au NPs@NC-Zn O/ITO)have been investigated by XRD,XPS,SEM and TEM.In the study of electrochemical detection,the electrochemical sensor has been established by direct using Au NPs@NC-Zn O/ITO as working electrode.Compared with NCZn O/ITO and Au-Zn O/ITO electrodes,the Au NPs@NC-Zn O/ITO electrode exhibits excellent sensing performance for electrochemical detection of hydrazine.The linear detection range,detection limit and selectivity of Au NPs@NC-Zn O/ITO have been investigated by I-t curve.All these observations indicate Au NPs@NC-Zn O/ITO have excellent performance for electrochemical detection of hydrazine.