Preparation Of Graphene-based Composites Modified Electrodes And Their Application In The Environmental Analysis

Graphene, a new type of two-dimensional carbon nanomaterial, has shown itsfascinating applications in electroanalytical chemistry because of its remarkableproperties, such as large surface areas, high electrical conductivity and excellentelectrocatalytic activity. For the construction of chemically modified electrodes withgood performance, functionalized graphene and its composites are used as modifiedelectrode materials, which is a new research hot spot in the field of electrocatalysisand electrochemical sensors. In this thesis, three different types of graphene-basedcomposites modified electrodes were fabricated by chemical doping,electropolymerization and electrodeposition, which could be applied into the analysisand detection of phenolic organic pollutants in the environment. The major contentsare described as follows:1. A three-dimensional nitrogen-doped graphene (NG) modified electrode wasfabricated by dropping the suspension of NG in water onto the glass carbon electrode(GCE), and it was also characterized. Compared with bare GCE and two-dimensionalgraphene modified electrode, the NG modified electrode exhibited highlyelectrocatalytic activity and good sensitivity toward the oxidation of hydroquinone(HQ) and catechol (CC). The peak current of HQ was linear to its concentration in therange of3.10×107to1.31×105M and the peak current of CC was linear to itsconcentration in the range of2.50×107to1.29×105M. The detection limits were1.0×107M and8.0×108M for HQ and CC (S/N=3), respectively. Moreover, theproposed method was successfully applied into the simultaneous determination of HQand CC in real water samples with satisfactory recoveries.2. The novel poly (L-proline)/graphene composite film (poly (L-Pro)/ERGO)modified electrode was developed through a facile, green and one-stepelectropolymerization process from graphene oxide and L-proline precursors. Thepoly (L-Pro)/ERGO modified electrode possessed the advantages of both poly (L-Pro)and ERGO with a synergistic effect, which could be used for simultaneousdetermination of HQ and CC with high sensitivity. Under the optimized conditions,the oxidation peak current increases linearly with concentration of HQ ranged from 5.00×107to2.57×105M and concentration of CC ranged from3.00×107to3.05×105M, respectively. The detection limits were1.6×107M and1.0×107M forHQ and CC (S/N=3), respectively. Moreover, the poly (L-Pro)/ERGO modifiedelectrode exhibited good reproducibility and stability, which was also applied into thesimultaneous determination of HQ and CC in tap water samples with satisfactoryrecoveries.3. A graphene-Au nanocomposite film (ERGO-Au) modified electrode wasprepared by using a coelectrodeposition technique. The electrochemical behavior ofbisphenol A at the ERGO-Au modified electrode was investigated. The ERGO-Aumodified electrode displayed high electrochemical activity in giving an oxidationpeak current that is proportional to the concentration of bisphenol A in the range from3.00×108to1.30×105M, with a detection limit of1.00×10-8M (S/N=3).