Fabrication And Research Of Electrochemical Sensors Based On Functionalized Graphene Modified Electrode

Graphene is widely used in the preparation of a variety of functionalizednanocomposite materials due to its excellent mechanical, optical, thermal andelectrical properties, and has a great application value in the optical, electrochemical,catalytic, and many other fields. However, Graphene is hydrophobic and easy toagglomerate, even would back to graphitization just due to Van der Waals forces,which greatly limit its further application. Therefore, the effectively modified andfunctionalized of the graphene is particularly important.Molecularly imprinted polymers(MIP)developed very rapidly in recent yearsbecause of its structure-activity predetermination and specific molecular recognitionability to the mimic natural receptor, while it also has stable physical and chemicalproperties, it is able to bear high temperature, and although can bear acid, alkalinereagents and organic corrosion, etc. Therefore graphene developed very rapidly inrecent years. MIP film as the recognition element applied to build a new generation ofelectrochemical sensors has considerable application prospect.In this dissertation, we establish graphene matrix composite electrochemicalsensors by combining graphene composites with electrochemical sensors andmolecularly imprinted technology. Detection of objects involved in drug moleculesand environmental pollutants. Mainly has carried out the following work:The first chapter is the introduction part. The view about the aspects of thestructure, preparation and application of graphene are given; The principle andcharacteristic of molecular imprinting technique and its application in theelectrochemical sensors are reviewed. Also, the topic ideas and research content ofthis thesis is summarized.The second chapter is prepared poly(diallyldimethylammonium chloride)(PDDA)functionalized graphene modified electrode (PDDA-G/GCE) as a electrochemicalsensor toward determination of4-nitrophenol. Compared with the bare electrode, themodified electrode has good catalytic effect, which greatly improves the reductionpotential of the4-nitrophenol. The linear voltammetry results show that the peakcurrent was linear to4-nitrophenol concentration in the ranges of0.06μM to110μMwith a detection limit of0.02μM (S/N=3) Compared to other sensors, this sensor for the determination of4-nitrophenol has low detection limit and successfully applied todetermine trace amounts of4-nitrophenol in actual water samples with satisfactoryresults.The third chapter is the preparation of a kind of molecularly imprinted membranewith the pesticide carbaryl recognition properties by electro-polymerization method,namely co-polymerization of acrylamide (AM) and carbaryl template molecule on theionic liquid graphene composites modified glassy carbon electrode surface and toprepare a PAM-IL-EGO polymeric film. The adsorption and molecular recognitionperformance of the imprinted polymer sensor to the template was studied bydifferential pulse method. The results show that the sensor for the template carbarylhas good recognition performance for the interfering substances with similar structurein solution, and to achieve the detection of carbaryl, the linear range and detectionlimits were1nM-0.24μM,0.3nM. This method has showed the advantages of highselectivity, wide linear range, low detection limit and low cost for the electrochemicaldetection of the substances containing non-active ingredients.