| In recent years,graphene has attracted a great deal of attention in the field of electrochemistry and electrochemical sensing with its unique properties.However,there are certain limitations when using intrinsic graphene as an electrode modifier.Therefore,to take full advantage of the electrochemical sensing properties of graphene,graphene must be effectively functionalized to improve the above-mentioned deficiencies.Among various functionalization methods,metal nanoparticles-graphene composites?MNPs-GR?have attracted great attentions.The metal nanoparticles in the MNPs-GR composite material not only can greatly improve the dispersibility of the graphene,but also lead to an“active site”on the surface of the graphene.On the other hand,the graphene also provides an ideal carrier for high activity immobilization of the metal nanoparticles,and therefore,can increase its electrochemical activity.At the same time,the composite material also has the advantages of graphene and metal nanomaterials,and can greatly improve the analytical performance of the sensor.In this paper,the preparation methods of reduced graphene oxide?RGO?,metal nanoparticle-reduced graphene oxide composites?MNPs-RGO?and their applications in electrochemical field have been reviewed.Based on this,gold and copper nanoparticles-reduced graphene oxide composites modified electrodes have been fabricated by drop coating method and electrochemical co-deposition techniques.Then,the resulting modified electrodes are charecterized by modern material characterization techniques and electrochemical methods.Furthermore,these prepared modified electrodes have also been applied to detect sulfite,nitrite,hydrogen peroxide,and hydrazine in environmental samples.The main contents of this thesis are as follows:1.A gold nanoparticles-reduced graphene oxide composite?AuNPs-RGO?was prepared by one-step co-reduction technique using ethylene glycol as reducing agent,solvent and stabilizer from a mixed solution containing of GO and HAuCl4.The composite material was modified on electrode by a drop coating method,and the electrochemical behavior of sulfite and nitrite on the electrode was studied.The results showed that graphene oxide provides active sites for the loading of gold nanoparticles,while the gold nanoparticles improve the dispersion of graphene oxide,making the activity of the composite materials increase.The modified electrode exhibits high electrocatalytic activity for the oxidation of sulfite and the reduction of nitrite.Under the optimization of preparation conditions of composite materials and the detection conditions of sulfite and nitrite,the linear range of sulfite by amperometry in 0.1 mol·L-1H2SO4 solution was from 2.0×10-77 to 2.3×10-3 mol·L-1,the detection limit was 4.5×10-8 mol·L-11 and sensitivity was 100.6?A·mM-1.The linear range of nitrite by amperometry in 0.1 mol·L-1 H2SO4 solution was from 5.0×10-7 to 4.7×10-3 mol·L-1,the detection limit was 1.5×10-7 mol·L-1 and sensitivity was 23?A·mM-1?2.AuNPs-RGO-MWCNTs composite was prepared by One-step reduction method,and the composite was modified on glassy carbon electrode by drop coating to prepare AuNPs-RGO-MWCNTs composite modified electrode.The results showed that nano composite materials provide more active sites for the gold nanoparticles compared to single material,this composite has some excellent characteristics such as small particle size,good dispersion as well as high electrocatalytic activity.Due to the synergistic action of each component,the modified electrode has high catalytic activity.Under optimized conditions,the electrochemical behavior of nitrite on this electrode was studied in PBS buffer solution?PBS??pH=5.0?.The linear range of nitrite by amperometry was 2.0×10-82.2×10-3 mol·L-1,the detection limit was 6.4×10-9mol·L-1 and sensitivity was 104?A·mM-1.3.The AuNPs-RGO-MWCNTs composite material was modified on GCE,and then CuO was deposited on the surface of AuNPs-RGO-MWCNTs/GCE by electrochemical deposition technology,and the copper oxide-gold nanoparticles-reduced graphene oxide-multiwallcarbonnanotubescompositefilmmodifiedelectrode?CuO-AuNPs-RGO-MWCNTs/CCE?was prepared.The results showed that this modified electrode had high electrochemical activity for the reduction of hydrogen peroxide with the synergic action of CuO,AuNPs,GO and MWCNTs.Under the optimum conditions,the linear range of amperometric detection of H2O2 was 5.0×10-74.9×10-44 mol·L-1,the limit of detection was 1.9×10-77 mol·L-11 and sensitivity was 374?A·mM-1.4.The CuNPs-RGO-MWCNTs composite was prepared by One-step reduction method,then the composite was modified on glassy carbon electrode by drop coating,and the CuNPs-RGO-MWCNTs/GCE modified electrode was prepared.The electrochemical behavior of hydrazine on the modified electrode was studied in PBS?pH=7?buffer solution.The results showed that this modified electrode had high electrochemical activity for the electrooxidation of hydrazine with the synergic action of CuNPs,GO and MWCNTs.Under the optimum conditions,the linear range of amperometric detection of hydrazine was 5.0×10-82.2×10-3 mol·L-1,the limit of detection was 1×10-88 mol·L-11 and sensitivity was 65?A·mM-1. |
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