Preparation And Applications Of Five Kinds Of Carbon Dots

Carbon dots(CDs)have attracted much attention due to its excellent optical properties,good biocompatibility,low preparation cost,difficult photobleaching,easy functionalization,and low toxicity,as a noval fluorescent carbon material.CDs have broad application prospects in the fields of sensing and detection,biological imaging,catalysis,energy storage,and optoelectronic devices,owing to its advantages.CDs with short-wavelength(blue or greenlight regions)have reported a lot,but CDs with long-wavelength(yellow or red regions)have difficult to prepare.In addition,the fluorescecence of CDs was quenched due to direct?-?interaction or excessive resonance energy transfer causing aggregation,it hinders the direct application of CDs in optical equipment,fingerprint development and sensors.Based on this,the luminescence behavior and detection function of CDs are adjusted through composite materials preparation,heteroatom doping,and temperature control.The research content of this paper includes three parts:1.A ratio fluorescence nanosensor based on CDs was designed and applied to the detection of cysteine.In the presence of cysteine,the sensor exhibited the characteristic emission of probes and Si CDs at a single excitation wavelength.This ratio fluorescence sensor has more selective for cysteine than other biological thiols(such as:aspartic acid,glycine,homocysteine).The detection limit is 0.73?M.In addition,the ratio fluorescence sensor can be used to detect the cysteine content in human serum sample.2.With dithiosalicylic acid and urea as raw materials,yellow and red solid luminescence CDs were prepared by controlling the reaction temperature and using a solvothermal method.Its morphology was characterized by transmission electron microscopy(TEM),the result shows that its diameter is decreased with the reaction temperature increases.The optical property and quenching mechanism of CDs indicate that the different luminescence of two CDs is caused by different luminescence centers.CDs have been used in fingerprint imaging and LED in view of their self quenching property.CDs have good development ability on different substrates.The details of latent fingerprints can be observed.It realized that the latent fingerprint is detected with high sensitivity and resolution.We explored its application for white or color LED.The carbon dots can not only be packaged with UV chips to obtain yellow and red LED,but also be packaged with the chip in a specific ratio to obtain a white LED.3.With dithiosalicylic acid and o-phenylenediamine as raw materials,hydrophobic CDs with red solid-state luminescence and different dispersion state luminescence were prepared by one-step solvothermal method and controlling the reaction temperature.The optical properties of the two CDs showed that the solid state and the dispersed state exhibit different optical properties,it exhibited excitation-independent optical properties in the solid state,and it exhibits excitation-dependent properties in the liquid state.Applications of CDs in fingerprint imaging and LED were researched.CDs have good development ability on different substrates.The details of latent fingerprints can be observed.It realized that the latent fingerprint is detected with high sensitivity and resolution.In addition,the CDs can be packaged with the ultraviolet chip to obtain a red LED individually,which can be used as a light conversion phosphor in red LED.At the same time,the water content in ethanol was measured by the color change of CD_S-200 in solid state and dispersed state.