| Graphene materials have been widely studied in electrochemical sensing for their unique physicochemical properties.However,there is a serious agglomeration between the graphene sheets,so that the active components modified on the electrode surface will be trapped inside and the modified layer not fully exposed,which affects the utilization efficiency and electrochemical activity of the electrode.This problem can be effectively solved by preparing the electrochemical sensing interface of 3D structured graphene materials.Compared with low-dimensional graphene materials,three-dimensional structured graphene materials,with large surface area,porosity,interconnected conductive networks and special microenvironment,can significantly accelerate the interfacial charge transfer speed rate and mass transfer rate.Moreover,using 3D structured graphene as the carrier can further load other active components and improve the sensing performance of the electrode.In this paper,based on the review of the application of 3D graphene composite in the electrochemical sensing,we have prepared 3D-polypyrrole-reduced graphene oxide composite film modified electrode,3D-gold nanoparticle-polypyrrole peroxide-reduced graphene oxide composite film modified electrode and 3D-gold nanoparticle-graphene doped-polypyrrole peroxide-multi-walled carbon nanotube composite film modified electrode by electrochemical method and they’re separatly applied in the electrochemical sensing of dihydroxybenzene isomers,hydrazine,phenol and 4-tert-butyl phenol.The main contents of the paper are as follows:1.Graphene oxide-polypyrrole composite film has been constructed by direct electrochemical method using graphene oxide as anion dopant.After electrochemical reduction and peroxidation treatment,a three-dimensional structure of polypyrrole peroxide-reduced graphene oxide composite film modified electrode（3D-OPPy/ERGO/CCE）was obtained.The results show that the 3D structure of the composite film increases the effective area and interfacial permeability of the electrode.The introduction of peroxidation polypyrrole improves the distinguishing effect of the electrode,and the introduction of reduced graphene oxide improves the electrochemical activity of the interface.With the synergistic action of various factors,the electrode can be used for simultaneous detection of the dihydroxybenzene isomers.Under the optimized conditions,the linear range for individual determiantion of hydroquinone by DPV was 2.0×10-7-2.0×10-4mol·L-1and 2.0×10-4-5.0×10-4mol·L-1,with a detection limit（3sb）of 3.3×10-88 mol·L-1.For catechol,the linear range and detection limit（3sb）was 5.0×10-7-4.0×10-44 mol·L-11 and 1.7×10-88 mol·L-1,respectively.For resorcinol,the linear ranges were 2.0×10-6-1.0×10-4mol·L-1and 1.0×10-4-5.0×10-4mol·L-1,with a detection limit(3Sb)of 6.7×10-7mol·L-1.Under the optimized conditions,the linear range for simultaneous determination was 5.0×10-7-1.0×10-4mol·L-1（hydroquinone）,5.0×10-7-2.0×10-4mol·L-1（catechol）and 2.0×10-6-2.0×10-4mol·L-1（resorcinol）,respectively.The detection limits(3Sb)was 1.0×10-7mol·L-1（HQ and CC）and 7.0×10-7mol·L-1（RS）,respectively.Compared with other electrochemical sensors based on graphene materials,the proposed method in this experiment has the characteristics of simple preparation procedure and strong bonding of modified materials on the electrode surface.2.Based on 3D-OPPy/ERGO composite film having good carrier action and using electrochemical method,3D-AuNPs-OPPy/ERGO composite film modified electrode was prepared by introducing gold nanoparticles to the surface of 3D-OPPy/ERGO composite film.The results show that in this composite film,gold nanoparticles were mainly deposited on the surface of the OPPy/ERGO composite diaphragm layer,and the composite film still exhibits an obvious three-dimensional porous structure.At the same time,the electrochemical activity of the interface was improved after the introduction of AuNPs in the composite film.The modified electrode exhibited high catalytic activity for the electrode process of hydrazine under the synergistic action of various factors.Therefore,we established the determination method of hydrazine in water sample.Under optimized experimental conditions,the linear range of detection of hydrazine by amperometric method was 1.0×10-7-8.3×10-4mol·L-1,the detection limit(3Sb)was5.2×10-8mol·L-1,and the sensitivity was as high as 380μA·mM-1.Compared to the reported sensors,the modified electrode has the characteristics of low detection limit,wide linear range,high sensitivity and good stability when used for hydrazine detection.3.A 3D-graphene quantum dots-polypyrrole peroxide-carbon nanotube composite film was prepared by electrochemical method.Based on this,gold nanoparticles have been further introduced on the electrode surface and a 3D-gold nanoparticles/graphene quantum dots-polypyrrole peroxide/carbon nanotube composite film modified electrode was obtained.The results show that the 3D-graphene quantum dots-polypyrrole-carbon nanotube composite film has a larger specific surface area and more active sites,which can be used as a good carrier for the loading of gold nanoparticles.With various components in the composite film,the modified electrode showed high catalytic activity and distinguishing effect on 4-tert-butylphenol and phenol.Under the optimized conditions,the linear range of by DPV for the determination of 4-tert-butylphenol and phenol alone was 1.0×10-7-1.0×10-4mol·L-1and 2.0×10-7-4.0×10-4mol·L-1,respectively.The detection limit（3sb）was 7.0×10-88 mol·L-11 and 1.0×10-77 mol·L-1,respectively.The linear ranges for simultaneous determination of 4-tert-butylphenol and phenol were 1.0×10-6-1.0×10-4mol·L-1and 5.0×10-6-3.0×10-4mol·L-1.The detection limits（3sb）were 3.0×10-77 mol·L-11 and 1.0×10-66 mol·L-1. |
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