Synthesis And Applications Of Several Carbon-based Nanomaterials

Carbon-based nanomaterials are dispersed phase with at least one-dimensional sizes below 100 nm,which can be made of carbon atoms or other atoms.Up-to-date,researchers have reported a number of carbon-based materials,including fullerenes,carbon nanotubes,graphene,fluorescent carbon dots and their composite materials.Carbon-based nanomaterials are superior to other materials in physical and chemical performance such as hardness,heat resistance,optical property,radiation-resistance property,electrical insulation,electrical conductivity,corrosion resistances,surface and interface characteristics,and so on.Carbon-based nanomaterials almost cover all the properties that all the substances on earth have,such as the characteristic of the hardest or the softest,the characteristics of excellent absorption or excellent transparency,insulators or semiconductors or good conductors,insulation or good thermal conductivity,and so on.Therefore,carbon-based nanomaterials have a wide range of applications.The development of new method or new technology suitable for the synthesis of these materials and the research of the effect of micro/nano structure on the properties of these materials have not only important for theoretical value,but also important practical significance for rapid development in the energy and the life analysis field.In this thesis,in order to meet the new requirements of the application in the energy and life analysis field,studies on the method to prepare the functionalized carbon-based nanomaterials through microwave hydrothermal or solvent thermal method were carried out.Furthermore,the relationship between the structure of carbon-based nanomaterials and their properties was primarily explored,and the applications of the as-prepared carbon-based nanomaterials in the energy and biological analysis field were also studied.The main points of this thesis are briefly summarized as follows:1.Microwave-assisted in situ synthesis of graphene/poly(3,4-ethylenedioxythiophene)hybrid and its application in supercapacitors.In this work,we report a novel in situ synthesis of graphene/poly(3,4-ethylenedioxythiophene)(G/PEDOT)hybrid through microwave heating by using graphene oxide/3,4-ethylenedioxythiophene(GO/EDOT)compounds as the single-source precursor.First,the GO dispersion was mixed with EDOT,and GO/EDOT compounds were formed through a strong adsorption between EDOT and GO.Then,under microwave heating,the adsorbed EDOT monomer on the GO surface was oxidized by GO and polymerized in situ to form PEDOT,and the GO can be reduced simultaneously to produce the G/PEDOT hybrid.In this strategy,no reducing agent(EDOT)or oxidizing agent(GO)existed in the synthesized product,which guaranteed the purity of the G/PEDOT hybrid.The as-prepared G/PEDOT hybrid was characterized.The electrochemical properties of G/PEDOT hybrid electrodes were investigated by cyclic voltammetry and galvanostatic charge-discharge measurements.The G/PEDOT hybrid as a supercapacitor electrode material afforded high specific capacitance and good cycling stability during the charge-discharge process.The method developed in this study opens up a simple and fast route to prepare graphene-based hybrid materials with broad application prospects.2.The preparation of G/PEDOT hybrid with adjustable ratio of graphene and PEDOT for supercapacitorsFor the G/PEDOT hybrid prepared in the above mentioned method,the ratio of graphene and PEDOT was restricted and the amount of PEDOT was determined by the EDOT monomer adsorption on the surface of graphene.In this work,in order to further explore the electrochemical performance of the G/PEDOT hybrid,different proportions of the G/PEDOT hybrid have been achieved by controlling the mass ratios of GO and EDOT under the microwave heating.The morphology,structure and composition of the hybrid were characterized by scanning the electron microscope(SEM),energy dispersive X-ray spectroscopy(EDX),EDX mapping,Raman spectroscopy,and X-ray diffraction(XRD).Moreover,the electrochemical properties of the different G/PEDOT hybrid electrodes were investigated by cyclic voltammetry(CV)and galvanostatic charge-discharge measurements.The results showed that different proportions of the G/PEDOT hybrid exhibited different specific capacitance.When the mass ratios of GO and EDOT was 2:1(the sample N2),the G/PEDOT hybrid exhibited the maximum specific capacitance(362 F g-1)at a current density of 0.5 A g-1 in 1 M H2SO4 electrolyte solution.3.Hair fiber as a precursor for synthesizing of sulfur-and nitrogen-co-doped carbon dots with tunable luminescence properties and its biological applicationsIn this work,a novel one-step approach was developed for the large-scale synthesis of sulfur-and nitrogen-co-doped carbon dots(S-N-C-dots)by using sulfuric acid carbonization and etching of hair fiber.This approach is simple and low cost.It may provide an efficient strategy to synthesize heteroatom-co-doped carbon dots.Moreover,the composition and size of the as-prepared S-N-C-dots were controlled by changing the conditions of synthesis.As a result,the photoluminescence properties of the resulting S-N-C-dots varied with the composition of the S-N-C-dots.That is to say,higher reaction temperature was in favor of the formation of S-N-C-dots with smaller size,higher S content,and longer wavelength of photoluminescence emissions.The resulting S-N-C-dots also exhibited good luminescence stability,low toxicity,good biocompatibility,and high solubility.Thus,as the fluorescent probe,they could be used for biological applications in the bioimaging and biolabeling.