Preparation Of Multicolor Fluorescent Carbon Quantum Dots By Microwave Method And Its Application In Detection And Imaging

Carbon dots are a new type of fluorescent carbon nanomaterials with bright luminescence,high chemical inertness,excellent biocompatibility,low toxicity,and good solubility.Since its first discovery in 2004,researchers paid much attention for it.Carbon dots have shown greatly potential application in the fields of information encryption and security,chemical sensing,bioimaging,photodynamic therapy,photocatalysis,and so on.However,there are still some problems to be solved urgently.Firstly,the photoluminescence quantum yield(PLQY)of purely solid carbon dots is very poor.The photoluminescence mechanism of purely solid carbon dots is not very clear.Carbon dots always suffer aggregation caused quenching(ACQ)in solid state.All of these problems seriously have impeded the potential application of solid carbon dots.Secondly,the catalytic efficiency of zinc oxide catalyst need be improved;Finally,the content of Fe³⁺is related to the environment and human health.It is necessary to monitor the concentration of ferric ions in the environment and human body.We carried out a simple and fast microwave method to synthesize purely solid state carbon dots which have higher PLQY without any further treatments.We also analyzed the photoluminescence mechanism of purely solid state carbon dots.By adjusting the ratio of nitrogen and sodium to tune the solid carbon dots luminescence,we have achieved the tunable dual fluorescence emissions of carbon dots.To the best of our knowledge,we obtained the purely solid state carbon dots with the highest PLQY until now.Our solid carbon quantum dots have good thermal stability and biocompatibility,which will have good application prospects in the field of light-emitting devices and bioimaging.Using urea,citric acid and zinc oxide as raw materials,a composite material of zinc oxide and carbon dots was prepared.By adjusting the excitation wavelength,the luminescence of the composite material can be controlled.The composite material could play a great role in the field of light emitting devices and photocatalysis.We used thiamine and L-malic acid as raw materials to synthesize nitrogen and sulfur double-doped carbon dots to detect the content of Fe³⁺and analyzed detection mechanism.This method was simple,fast,environmentally friendly and efficient.We also tested the light and thermal stability of nitrogen and sulfur double-doped carbon dots,which demonstrated nitrogen and sulfur double-doped carbon dots have potential application in the field of light emitting devices.