Research On The Preparation And Functionalization Of Carbon Quantum Dots

As the new member in the field of nanometer materials,carbon quantum dots has been casing extensive concern due to its superior resistance to photobleaching,chemical inertness,low toxicity and good biological compatibility.Carbon quantum dots has advantages of low cost,stable optical properties,long fluorescence lifetime and excitation spectrum independence compared with traditional semiconductor quantum dots with the size of 10nm or less,being one of the most potential carbon nano materials gradual in the fields ofbiological imaging and sensing,photocatalysis,photoelectric conversion and ion sensors.The synthesis methods to prepare carbon dots are divided into two kinds:one of them is "top-down",including hydrothermal synthesis,ultrasonic and electro chemical stripping,etc;the other one is "down-top",such as microwave radiation,template method and chemical oxidation method,etc.The emergence of carbon quantum dots greatly enriched the application scope of carbon materials,but complex post-processing,low yield and fluorescent color deficient limit its application in actual Therefore,it is extremely necessary to develop rich source,low cost,high production rate of carbon source.In this study,we try to improve and optimize the synthesis methods from the following two aspects:carbon quantum dots is prepared by choosing cheap carbon source and decorated with amino acid doped on its surface;changing the subsequent processing conditions of as-prepared product to improve its optical property and then applied in metal ion detection Concrete research content is as follows:1.Citric acid as the carbon source,leucine as nitrogen source to prepare the new type N doped carbon quantum dots(NCDs)through the hydrothermal method.The experiment is easy to operate and efficient with the product water-soluble.The as-prepared product could emit bright blue fluorescence under 365 nm ultraviolet lamp.Under optimal conditions,Fe3+ could interact with NCDs and the fluorescence quenchs remarkably.Therefore,NCDs can be used as Fe3+ probe.2.New carbon nanomaterial carbon dots(CDs)were obtained via a one-step microwave irradiation method using glycerin as carbon precursors and solvent.TEM results showed that the CDs diameters were not uniform but distributed in the 4-25 nm range,with an average value of 16.5nm.Fluorescence research shows that the carbon quantum dots on the metal Fe3+ showed excellent choice identification in aqueous solution compared with Cu2+,Ca2+,Mn2+,Co2+,Fe2+,Ni2+,Zn2+,Na+,Cd2+,Mg2+,Pb2+,K+ and Ag+13 kinds of common metal ions.Under optimal conditions,the CDs can be used as sensors and exhibited a "turn-off" fluorescence response to Fe3+.3.Two kinds water-soluble nitrogen-doped quantum carbon dots(N1-CDs and N2-CDs)could be obtained by one-step solvothermal method from same starting material of L-tyrosine and citric acid under different processing temperatures and emit strong fluorescence situated at 465 nm and 515 nm,respectively.Interestingly,the obtained N-CDs could.exhibit highly sensitive fluorescence "turn-off" response toward Cu2+ or Fe3+ in aqueous system,and the solution color change could be clearly observed by naked eyes.The fluorescence lifetime experimental result demonstrates that the mechanism of the quenching process involves complexation interaction and the dynamic quenching dominates over static quenching.N2-CDs was further applied to detected trace Fe3+ in real water sample.