Research On Modification And Application Of Carbon Dot And Titanium Dioxide

Energy shortage and environmental pollution are serious practical problems that cannot be avoided worldwide.With the increasingly in-depth research in the field of new materials,semiconductor photocatalysts have potential application value in the field of photoelectric conversion and photocatalytic degradation.The core of research on photocatalysts lies in the development of stable,efficient,and inexpensive photocatalysts.Among many photocatalysts,titanium dioxide has a suitable band gap width,and is stable in nature.It is cheap and easy to prepare,and has received the attention and in-depth research of experts and scholars.Therefore,this thesis focuses on titanium dioxide and studies the effects of doping modification and development of new structures on its photocatalytic activity.The following is the specific research content of this thesis:First,carbon dots with different elemental compositions were prepared by hydrothermal synthesis and solvothermal synthesis.The diameters of the carbon dots under the electron microscope are 5-15 nm,the dispersion is good,and there is almost no agglomeration;the high magnification transmission electron microscope can be observed that the carbon dots have obvious(101)plane lattice fringes;X-ray energy spectrum The analysis shows that the nitrogen-doped carbon dots contain only nitrogen,carbon,and oxygen elements,and the nitrogen atoms are mainly replaced by pyridine nitrogen and inserted into the carbon ring.The results of ultraviolet visible spectrum analysis and fluorescence spectrum analysis show that several types of carbon Among the dots,nitrogen-doped carbon dots have strong light absorption in the ultraviolet region,and the fluorescence emission is stable without being affected by the excitation wavelength.It can be inferred from the excellent fluorescence performance and ultraviolet absorption performance of carbon dots that carbon dots have the potential to be used in the field of photocatalysis and photoelectric conversion.The carbon dots and polyvinylpyrrolidone are uniformly mixed as a spinning precursor solution for electrospinning to obtain fluorescent nanofibers.This proves that the carbon dots have good stability.The fluorescent nanofibers are promising for the production of flexible fluorescent plastic film products,and the fluorescent patterning of textile fiber woven products,which provides the basis for solid-state fluorescent detection sensors,anti-counterfeiting fluorescent labels and other application research.A titanium dioxide nanorod array with good morphology was grown hydrothermally on a commercial fluorine-doped conductive glass substrate.Under the high magnification observation of the electron scanning microscope,by adjusting the solvent heat temperature,the amount of titanium source,and the precursor ratio,a uniform and uniform nanorod array can be obtained.In the nanorod array with the best shape,the average diameter of the nanorods is about 70 nanometers.The array thickness is 230 nm.It was verified by X-ray diffraction that titanium dioxide was a mixed crystal form of coexistence of rutile and anatase;the bond formation in titanium dioxide nanorods was studied and analyzed in depth by Fourier infrared spectroscopy.Carbon dot-modified TiO2 nanorods were prepared by two methods of physical immersion adsorption and in-situ growth,and two sets of modified nanorod arrays and unmodified original nanorod arrays were used as counter electrodes to assemble dye-sensitized solar cells for photoelectric performance.test.The results show that the efficiency of the modified nanorod battery is significantly higher than that of the unmodified carbon dot battery.Similarly,the efficiency of the carbon dot modified titanium dioxide layer prepared by the immersion adsorption method is slightly higher than that of the in-situ method.Finally,based on the electrospinning method and nitrogen protection high temperature sintering heat treatment to obtain titanium dioxide nanofibers,cobalt acetate tetrahydrate and ferric nitrate nonahydrate were added to the precursor solution,and the iron-cobalt double transition was prepared after spinning and sintering Metal-doped titanium dioxide nanofibers.The X-ray diffraction method was used to study the crystalline form of nanofibers when the sintering temperature was gradually increased.X-ray photoelectron spectroscopy results show that the titanium ions in the fiber are mainly tetravalent,and iron-cobalt metal ions are successfully doped into the fiber.The ultraviolet-visible diffuse reflection can calculate the fiber band gap,and the results show that the doped fiber band gap is significantly reduced,which is helpful to improve the photocatalytic performance of the fiber.The experiment of the fiber degradation of the dye Rhodamine B under mercury lamp irradiation can be obtained TiO2 nanofibers doped with iron and cobalt have good photocatalytic activity.The degradation rate of rhodamine B was 48.9%under the doping condition of 5 wt%.All in all,this paper studies the preparation of carbon dots and the modification of titanium dioxide materials.A variety of element-doped carbon dots with fluorescent properties were prepared,and the green fluorescent carbon dots extracted from edible soy milk powder species were successfully created using solution electrospinning.Prepared as nanofibers,with excellent fluorescence and excellent fiber morphology.Carbon dot fibers greatly widen the application range of carbon dots,so that their fluorescent properties can play a role in more fields such as textile,filtration and tissue engineering,and contribute to the development and application of solid-state fluorescence technology.Nitrogen-doped carbon dots were used for the doping of the titanium dioxide nanorod array counter electrode,and the photoelectric conversion efficiency far exceeded that of the undoped counter electrode.The short-circuit current density was significantly improved,which proved that nitrogen-doped carbon dot doping mainly improves the electron transport capability of titanium dioxide.Focused on the electrospinning preparation of bimetallic doped titania composite nanofibers,through in-depth analysis of the microstructure and properties of iron-cobalt composite fibers through technical means.It was proved by photocatalytic degradation of dyes that the iron-cobalt composite fiber has good catalytic degradation efficiency.It is easy to separate from the water body,and can be used as an effective pollutant catalytic degradation material.