In-depth Study On Composite Materials Containing Carbon Dots And Semiconductors: Controllable Synthesis And Property Modulation

In recent years,with the progress of human and the development of science and technology,the development of semiconductor materials has been very rapid.Due to its unique electronic energy band structure,semiconductor materials have a controllable response to photoelectric signals.Therefore,such materials can be widely used in the fields of biological probes,nanomedicine,and electrochemistry.In order to further control the optoelectronic properties of semiconductor materials and prepare for the industrialization and commercialization of such materials,it is urgent to solve the problems of toxicity,stability,and cost of such materials.Therefore,the development of stable,efficient,and low-cost semiconductor composite materials has become a research hotspot in this field.Carbon dots,as a zero-dimensional material,have the characteristics of low price,stable room temperature,low toxicity,and easy loading.It can be used as a component of semiconductor composite materials to control the properties of other semiconductor materials.In this paper,based on the advantages of carbon dots,we further developed an efficient and controllable preparation method,and systematically studied the electronic structure properties of carbon dots-semiconductor composite materials.On this basis,we have tried to design and study the application of this type of material in a number of technology and medical fields,and have made great progre The synthesis method of carbon dots,carbon dot composite materials,the application of carbon dot@semiconductor composite materials,and the meaning and significance of the selected topics are introduced.In the first chapter,the research methods of carbon dots,carbon dot composite materials,the application of carbon dot@semiconductor composite materials are introduced.At last,the importance of the project is demonstrated.In the second chapter,s-N-CDs were synthesized through a one-step microwave-assisted hydrothermal method.s-N-CDs has good water solubility,dispersibility,uniform particle size,and an average size of 2.9 nm.s-N-CDs can be used as fluorescent nanosensors to detect pH,and can detect the pH of solutions or biological cells.When the pH changed from 14 to 2,the fluorescence intensity and fluorescence lifetime of s-N-CDs increased significantly.When the pH changed from 2 to 14,the fluorescence intensity and fluorescence lifetime dropped sharply.Not only that,s-N-CDs can also be used to detect VB 12,in several B vitamins,common metal cations and amino acids,to achieve specific detection of VB 12,and the detection line obtained is as low as 2.19?M.At the same time,we also explored the changes in the morphology and fluorescence properties of the corresponding fluorescent carbon dots when different kinds of biomass materials are used as carbon sources.In the third chapter,we have rationally designed,synthesized and characterized composite nanoparticles of copper sulfide and carbon dots(CuSCD)with a hollow structure.CuSCD nanoparticles have uniform size and good dispersibility.The average size is about 205 nm.At the same time,they exhibit excellent synergistic effects of enhanced photothermal conversion efficiency under 808 nm laser,enhanced biocompatibility,and reduced laser radiation toxicity.CuSCD was coated with macrophage membrane with T7 peptide,and then loaded with anticancer drug bortezomib to form CuSCDB@MMT7 composite nanoparticles.CuSCDB@MMT7 has an average size of about 222 nm,which is specific to cancer cells and promotes favorable immune escape and transferrin receptor-mediated endocytosis.In vivo and in vitro experiments have proved that CuSCDB@MMT7 has a certain anti-tumor effect,not only can effectively inhibit tumor growth,but also inhibit tumor metastasis.It also emphasizes a promising treatment strategy that can achieve enhanced therapeutic effects for effective clinical cancer treatment.In the fourth chapter,we first successfully prepared the layered compound LiVO₂with a hexagonal crystal structure by solid-phase synthesis.Then the synthesized LiVO₂material is modified with nitrogen-doped carbon dots.By adjusting the amount of carbon dots,different composite ratios of LiVO₂@CDs were obtained.The composite material is used as a new type of lithium battery anode material to obtain a high specific capacity,good stable cycling ability and excellent rate performance.Among them,the LiVO₂@10%CDs material can produce a reversible capacity of 172.8 mA h g^-1at a current density of 200 mA g^-1,at the same time,has a good high-rate capacity.The experimental research in this chapter shows that this excellent electrochemical performance of LiVO₂@CDs.Due to the loading of carbon dots,widening of the interlayer spacing of LiVO₂.The facilitates insertion and extraction of lithium ions which laid the experimental foundation and design ideas of high-performance lithium-ion batteries.The last chapter is the summary and prospect of the three research systems in this dissertation.