| Graphene as a new type of carbon materials in the field of electrochemical sensor has caused the researchers'attention.The reason mainly lies in:graphene has excellent electrical conductivity,can significantly accelerate the interfacial charge transfer rate,improve the sensitivity of electrochemical sensor.On the other hand,Graphene has large specific surface area can be used as a carrier to load other substances,so as to get graphene composite material,this kind of composite material with the advantages of graphene and other components,can significantly improve the electrochemical activity of the sensor and analyzes its performance.But the current construction of electrochemical sensor based on graphene and its composites interface is the basic idea of chemical synthesis of graphene and its composites first,then dispersed in a suitable solvent and drops onto the base surface of electrode.But graphene layers will reunite,make the most of the active components in the modified electrode surface layer,the internal and inadequate exposure of impact modifier of efficiency and electrochemical activity.In order to solve these problems,in recent years,researchers begin to pay close attention to the graphene material structure design and the control assembly.Among them,with continuous adjustable hole structure of 3D graphene material has attracted high attention.Three-dimensional structure of graphene can not only present a single layer?or rarely?properties of graphene,and interconnected holes,can effectively increase the specific surface area of material,speed up the interfacial electron transfer rate.Three-dimensional structure of holes is also conducive to the spread of the electrolyte ions and molecules object under test,and improve the sensitivity of electrochemical response signal.In this thesis,I door respectively by the methods of in situ reduction,electrochemical deposition and polymer embedding method step by step based on the three-dimensional structure of graphene composites chemical modified electrodes,the preparation conditions on the basis of a detailed study was carried out by its application in electrochemical sensor research,the main contents are as follows:1.The first was prepared by in situ chemical reduction method of reduction graphene oxide-multi-walled carbon nanotube composites?rGO-MWCNT?,and by using the method will drop coating modification to the surface of glassy carbon electrode,finally USES the direct electrochemistry method to palladium nanoparticles?PdNPs?deposit on the surface of electrode,thus obtained the palladium nanoparticles-reduction of graphene oxide-multi-walled carbon nanotubes composite film modified electrodes?PdNPs-rGO-MWCNTs/GCE?.Scanning electron microscopy,the experimental results show that the carbon nanotubes in compound can have the effect of similar frame,making composite materials formed the three-dimensional hierarchical structure in the structure,can provide more active point,electrodeposition,is beneficial to get a uniform particle size small,scattered PdNPs,significantly improve the PdNPs catalytic oxidation activity of oxalic acid.Under optimized conditions,differential pulse voltammetric?DPV?method was developed for the determination of oxalic acid in linear range of 1.0×10-55.0×10-3 mol·L-1,the detection limit of 4.8×10-6 mol·L-1.With literature reports,compared to other enzymes oxalic acid electrochemical sensor when the modified electrodes used in oxalic acid detection has a wide linear range,low detection limit,etc.2.Using electrochemical deposition of the gold nanoparticles prepared by two step-three dimensional reduction graphene oxide composite film modified electrodes?AuNPs-3D-ERGO/GCE?.Preparation conditions on the basis of detailed study,to study the electrochemical properties of the modified electrodes and the catalytic activity of nitrite with electricity.Results show that the three-dimensional porous structure of graphene can effectively increase the specific surface area of materials,to provide more active point,is beneficial to form a small particle size,uniform dispersion of gold nanoparticles,further speed up the interfacial electron transfer rate.At the same time,the three-dimensional structure effectively improves the interface to connect appear a gender,is advantageous to the supporting electrolyte ions and the spread of the material under test,improve the sensitivity of electrochemical detection of nitrite.Under optimized conditions,ampere?Amperometry?method was developed for the determination of nitrite linear range of 5.0×10-81.8×10-3 mol·L-1,the detection limit of 2.0×10-8mol·L-1.Compared with the results reported in literatures,the modified electrode has a wide linear range,low detection limit and high sensitivity.3.Use of anion of graphene oxide doped function by adopting the method of electrochemical reduction of graphene oxide was prepared first-polypyrrole composite film modified electrodes,in carries on the peroxide after processing,the electrochemical technology to deposit on the surface of the electrode ferrous cyanide in metal ferricyanide cobalt nickel-ferrous cyanide?NiHCF-CoHCF?,finally in sodium hydroxide solution,the mixed metal ferricyanide electrochemical derivatives into cobalt,nickel hydroxide mixed?Co?OH?2-Ni?OH?2?,which was Co?OH?2-Ni?OH?2-3D-rGO-OPpy/CCE composite film modified electrodes.Electrode preparation conditions on the basis of detailed study,to study the electrochemical properties of electrodes and electric catalytic oxidation activity of glucose.The results show that the 3D-rGO-OPpy for Co?OH?2-Ni?OH?2 load provides more active point,Co?OH?2-Ni?OH?2 mixture improve the catalytic activity of glucose,the electrode at the same time,the OPpy film improved the selectivity of the electrode,under the common role of above factors,the electrode to detect glucose with wide linear range,good stability and selectivity,etc. |
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