The Preparation And Electrochemical Properties Of Graphene And Carbon Quantum Dots Composite Material

In recent years,with the development and application of nano technology,nanomaterials composed of carbon,such as graphene,carbon quantum dots,carbon nanofibers and carbon nanotubes so on,can be prepared by adopting different raw materials and experiment methods.These carbon materials,especially carbon quantum dots?CQDs?and graphene?GP?,exhibit excellent application prospects.In order to enhance the electron transfer rate and surface electrochemical activity of the GP,the zero-dimensional CQDs were added into the two-dimensional GP,which is of great significance for the construction of high-efficiency and sensitive electrochemical sensing materials.In this thesis,the CQDs were synthesized in aqueous by hydrothermal method with coke powder as carbon source.The graphene-carbon quantum dots?G-CQDs?composite materials were prepared by adopting the GP as a carrier to load the CQDs.Then,the properties of GP,CQDs and G-CQDs composite materials were discussed,respectively.The functionalized G-CQDs composite materials with excellent properties were obtained.The main contributions of this paper were summarized as follows:?1?The CQDs were prepared by adopting coke powder as raw material by hydrothermal method.And the optimal preparation condition was determined by the yieldoffluorescentquantumofCQDs.Theresultsshowedthat the optimum reactive conditions of CQDs were reflux temperature 100?,pH value 9,and mixed acid volume 16 mL.The highest fluorescent quantum yield of the CQDs is about 34.27%.?2?The G-CQDs composite materials were synthesized by adopting the graphene as conductive frame to load CQDs.And the optimal preparation condition was determined by the cathode and anodic peak potential difference??Ep?of cyclic voltammetry?CV?.The results showed that the G-CQDs composite materials with the excellent electrochemical activity could be prepared when the mass ratio of GP:CQDs,heating reaction temperature and reaction time were 50:1,150?and 60 min,respectively.?3?The G-CQDs composite materials electrode were utilized as electrochemical sensor to detect uric acid,ascorbic acid and H₂O₂ small molecules.The results showed that the linear range of G-CQDs electrode on uric acid detection was 1-150?mol/L,the lowest detection limit?LOD?was about 0.011?mol/L,and the sensitivity was about 2319.4?A/?mmol/L·cm²?.The linear range of G-CQDs electrode on ascorbic acid detection was 800-9000?mol/L,the LOD was about 31.579?mol/L,and the sensitivity was about 53.1?A/?mmol/L·cm²?.The LOD of G-CQDs electrode on H₂O₂ detection was about 0.213?mol/L,and the sensitivity was about 2.5?A/?mmol/L·cm²?.