Study On Synthesis Of Fluorescent Carbon Dots,the Catalytic Activity,Application Of Ion Detection And Fingerprint Development

The carbon dots?CDs?has become one of the hot topics because of its unique size and excellent optical properties,which has attracted much attention in many cross fields.As low toxic nano material with rich functional groups on the surface,the CDs can be widely used in the fields of sensors,biological imaging,catalysis and optical device.In this paper,the orange and blue fluorescent CDs are synthesized by hydrothermal method.According to the fluorescence properties and response characteristic,several metal ion detection systems,catalytic system and latent fingerprint developing scheme are designed.First,rhodamine B was used as the raw material to synthesize orange fluorescent CDs?O-CDs?by hydrothermal method,exhibiting emission at 574 nm when excited at555 nm,with a fluorescence quantum efficiency of 46%.The O-CDs can emit strong fluorescence with the naked eye mode detection of Hg²⁺.The presence of Hg²⁺can cause the obvious fluorescence quenching signal of the CDs,which can be used for the high selectivity and sensitivity detection of Hg²⁺.Also,a test paper and a cellulose acetate film were prepared and effectively extended.According to the special fluorescence properties of the material,it can be applied for the latent fingerprint development.Studies on some specific substrates such as curved surfaces,multicolored surfaces and blue fluorescence backgrounds all showed good results.In addition,2-mercaptothiazoline and triethylenetetramine were selected as raw materials for the synthesis of the nitrogen and sulfur co-doped carbon dots?N&S CDs?.The CDs with bright blue fluorescence and fluorescence quantum yield of 40%was prepared by simple hydrothermal method,which can be used as a fluorescence detection probe for Cd²⁺with high sensitivity and good selectivity.The detection platform presented a good signal response in both ultra-pure water and real water samples with a fast fluorescence quenching signal within 2 minutes.The limit of detection is 0.18?M within the range of 0.02?1.00?M,and the quenching fluorescence behavior conforms to the static quenching effect.This article reported a one-pot hydrothermal strategy for preparing fluorescence carbon dots with magnetic properties?Fe₃O₄-CDs?.The Ammonium Ferric Citrate?AFC?and urea served as iron and nitrogen source and both as carbon sources were put into reaction solvent diethylenetriamine?DETA?,which was acted as reductant and nitrogen provider in the process of synthesis of Fe3O4-CDs.Further,a sensitive and rapid method based on the Fe₃O₄-CDs was utilized for detection of Hg²⁺,simultaneously accompanied with the magnetic removal process.A good linearity was obtained in range from 2.0 to 200.0 nM with a detection limit of 12.6 nM.The fluorescence quenching mechanism was proved to be caused by inner-filter effect?IFE?and static quenching effect?SQE?.More,this platform was successfully applied in analysis of Hg²⁺in real sample with satisfying recovery result providing a convenient monitoring strategy.Taking lipoic acid and triethylenetetramine as raw materials,the nitrogen and sulfur doped carbon dots?N/S CDs?were prepared by hydrothermal method.They have a blue fluorescence?with excitation/emission maxima at 340/456 nm?with a quantum yield of 35%.The N/S CDs can catalyze the oxidation of 3,3,5,5-tetramethylbenzidine?TMB?in the presence of H2O2,and this leads to the appearance of a blue solution with a absorption maximum at 654 nm.A colorimetric method was developed for the determination of H2O2 that has a 1.75?M detection limit and a linear response in the10^-5 to 10^-4 M concentration range.The method can be extended to the enzymatic determination of glutathione with a 0.26?M detection limit and a working range from0.20 to 100?M.In addition,the CDs respond to lead?II?which is a quencher of the blue fluorescence at 456 nm,with a detection limit of 11?M and a working range up to 100?M.Simultaneously,the color changes can be visually detected with absorbance signal changes from 10 to 100?M with limit of 3.9?M.A multiple detection system was worked out that allows monitoring of H2O2 and glutathione successively,and of lead?II?.