Study On Functional Light Emitting And Porous Carbon Materials Based On Carbon Nanodots Assembly System

Carbon nanodot is a kind of nanoparticle that is smaller than 10 nm and usually consists of carbon,hydrogen,oxygen,and nitrogen.As a new kind of carbon nanomaterials,carbon nanodots have the advantages of low toxicity,low cost and excellent biocompatibility.Carbon nanodots have been widely studied in recent years due to their excellent photoelectric properties.In terms of synthesis,the synthesis method of carbon nanodots is simple and fast,and the cost of raw materials is cheap.In terms of structure,carbon nanodots have carbon nuclei and abundant surface functional groups.Generally,they are spherical nanoparticles with a size less than 10 nm.In terms of properties,carbon nanodots have excellent luminescence properties and a large number of functional groups on the surface endow them with good modificability.Meanwhile,carbon nanodots have low toxicity and environmental friendliness.In terms of applications,carbon nanodots have been widely used in the fields of nano sensing,photocatalysis,biology and photoelectric devices.At present,the luminescence properties of carbon nanodots have been widely studied.By expanding the research,carbon nanodots can be used in many applications.The research on carbon nanodots in this paper is reflected in the following aspects :(1)by inducing the self-assembly of carbon nanodots in non-polar solvent,the aggregation of carbon nanodots can be induced to quench,and the water-induced fluorescence of carbon nanodots can be enhanced and used for fluorescence dual-encryption;(2)freeze-dried self-assembly method can be used to construct the corresponding assembly structure from carbon nanodots,and realize the high nitrogen-doped porous carbon frameworks based on the assembly system of carbon nanodots after high-temperature heat treatment;(3)to explore the application of porous carbon framework based on carbon nanodot assembly system in the field of alkali metal ion batteries.The specific content of this paper is as follows:Firstly,a series of nitrogen-doped carbon nanodots were prepared at different microwave power by using low-cost raw materials citric acid and urea as carbon and nitrogen sources,N,N-dimethylformamide or water as solvents,and different reaction ratios and reaction times.Fluorescence of carbon nanodots can achieve optical regulation from blue to green.By characterizing the structure of carbon nanodots,we found that carbon nanodots can self-assemble in non-polar solvents,and the supra-(carbon nanodots)assemblies of 100~250 nm can be constructed from carbon nanodots of several nanometers.Carbon nanodots with multicolor fluorescence were selfassembled to obtain supra-(carbon nanodots),which were then compounded with paper to obtain supra-(carbon nanodots)-paper composite.After being treated with water spraying,the fluorescence emission could be effectively enhanced due to redispersed carbon nanodots.The supra-(carbon nanodots)-paper composite can also be used for fingerprint collection and fluorescence dual-encryption combining water-jet printing and handwriting.The freeze-drying method can obtain the assembly structure with three-dimensional porous structure,and the high nitrogen-doped porous carbon frameworks based on the carbon nanodot assembly system can be obtained after the high-temperature heat treatment.Finally,we also obtained the alkali metal ions anode by using the porous carbon frameworks with high nitrogen doping as the active material,and assembled the coin battery by using lithium,sodium and potassium as the counter electrode.The experimental data show that the prepared carbon nanodot based porous carbon frameworks anode can be used in alkaline metal ion batteries such as lithium ion,sodium ion and potassium ion,and has good cycle stability and rate stability.