Study On The Preparation Of Photoelectro-renewable Electrode Based On Graphene Nanocomposite And Application In Electroanalytial Chemistry

As a new two-dimensional material,graphene has good physical and chemical properties.Due to its high surface area,execllent electrical conductivity and easy functionlization,graphene is often used as substrate materials to construct graphene-based composite electrodes.And it has been used in the fields of photoelectrocatalysis and sensors.The small biological molecules is an important object in electrochemical biological dection.The introduction of graphene based composite material in electrochemical biosensor can improve its sensitivity and selectivity.But in the complex biological samples are prone to non-specific adsorption,oxidation reaction or the aggregation,pollution or passivation electrode surface and lower electrode electrochemical response capacity,which affects the electrochemical sensors sensitivity and repestability.At present,the commonly used renewable electrode often adopts mechanical cleaning,the method such as electrochemical etching,or ultraviolet light to renewable mechanical cleaning.But the method is easy to damage the electrode surface microstructure,is not conducive to the stability of electrode assembly function layer,so the effective development of new and renewable method of biological small molecules dection is great important.Based on this problem,a novel graphene-based composite modified electrode was constructed in this paper,which was combined with electrochemical treatment under visible light irradiation to acheieve photoelectric regeneration of the electrode,and applied to the detection of uric acid（UA）in the presence of dopamine（DA）and sertonin（5-HT）contamination.（1）The larger size Graphene oxide（GO）can be prepared by airtight oxidation.And different size of GO were obtained by ultrasonic cutting and centrifugal separation.The corresponding size of redeuced graphene（rGO）was obtained by hydrazine hydrate reduction method.Adding GO,rGO into cationic cobalt porphyrin（TPPyP-Co）,respectively.Then,the graphene/cobalt prophyrin was obtained by the non-covalent interactin.The formation process and surface properties of the composite were characterized by uv-vis absorption spectrum,atomic force microscope and Zeta potential analyzer.The result show that the rGO size of 2⁴mM had the highest degree of recombination of rGO with TPPyP-Co.（2）The reduced graphene/cobalt prophyrin complex modified glassy carbon electrode（GC-rGO/TPPyP-Co）was obtained by trickle-coating on a glassy carbon electrode（GC）.By differential pulse voltammetry investigating the UA detection signal,in the presence of DA and 5-HT pollution on different electrodes.Then confirmed the stability of different electrodes under photoelectric chemical processing.Study about the GC-rGO/TPPyP-Co modified electrode for Daattached renewable effect,and the electrode will be applied to the detection of UA.And the optimal pH and load of UA were investigated.The results showed that the GC-rGO/TPPyP-Co electrode had a good cleaning effect on DA、5-HT adhesion,and the electrode have good reproducibility.At the same time,the detection of UA at pH=7 and load=2.54μg/mm²has good stability,selectivity and repeatability.In the range of 0.1～100μMUA、0.2～100μMUA concentration has good linear,and the correlation coefficient is0.9960、0.9985,the dection limit is 29.78 nM、43.41 nM.（3）Graphite phase carbon nitride（g-C₃N₄）was prepared by thermal condensation polymerization and g-C₃N₄nanometer-sheet was obtaiined by acidification and dispersion treatment.It was characterized by X-ray powder diffraction（XRD）and UV-Vis spectrophotometer.By controling the proportion of mixed prepared the rGO/g-C₃N₄complexes.Then modified it on the glassy carbon electrode（GC-rGO/g-C₃N₄）.And further studied the DA attaching and cleaning effect of the GC-rGO/g-C₃N₄complex electrode.The electrode was applied in the detection of UA.The results showed that the compound modified electrode has a good cleaning effect on the attachment of DA.At pH=7,the electrode has a good reproduction and reproducibility in UA detection,In the range of 0.2～100μMUA concentration has good linear,and the correlation coefficient is 0.996,the dection limit is39.08 nM.