Preparation Of Carbon Nitride Dots And Its Optical Applications

Carbon nanomaterials such as graphene,carbon nanotubes,carbon nanofibers,and carbon quantum dots have drowned increasing attention in recent years and have played an important role in the fields of catalysis,energy storage,and sensing analysis.Unfortunately,the synthesis methods for carbon nanomaterials usually be complex and limited to fabricating for a single kind of material,rarely can be applied to the synthesis of dozens.Among these nanomaterials,carbon quantum dots,as a new member of the carbon nanomaterial family,have been used in biological imaging and analytical sensing,etc.owing to their high fluorescence quantum yield,good light stability,good biocompatibility and low toxicity.However,there still has a great debation on the origins of the luminescence.Besides,the blue-shift photoluminescence,which is adverse to imaging applications,are always been observed due to the quantum confinement effect.Therefore,it is of great theoretical and applicable significance to develop new methods for preparing various carbon nanomaterials,including carbon quantum dots,carbon nanosheets and carbon nanorods.In addition,N-doping is an effective way to improve the structure and properties of carbon nanomaterials.g-C₃N₄,with a graphite-like structure,is a carbon nitride material of eigenstate luminescence properties.It is also an ideal precursor for top-down preparation of nitrogen-doped carbon nanomaterials.However,most of the reseraches are limited on their application in catalysis,optoelectronics,etc.Therefore,it is urgent to develop a new method to solve these problems.Inc conclusion,the dissertation is mainly focused on following two parts:1.A new method for top-down fabrication of carbon nitride nanomaterials was developed.The hot-tailoring?bulk pyrolysis-liquid collecting?method makes use of heat to cut bulk precursors into CN nanos.The CN nanos were carried into the collecting solvent immediately with the help of N₂ gas flow.After further purification,passivation and functionalization,the CN nanomaterials with uniform morphologies was obtained.Besides,the morphologies and properties can be finely tuned through changing proper precursors,recipes and collecting solvents.A possible thermo-cutting mechanism was proposed with the help of TG-MS.2.carbon nitride quantum dots?CNQDs?with a blue emission at 448 nm,about 18 nm longer than its precursor CN450 which emit at 430 nm,were successfully synthesized through hot-tailoring method.after further explored by XRD?FT-IR?XPS and EA,the results show that the carbon and oxygen content and the formation of oxygen-containing functional groups on the surface after solvent passivation have an important contribution to the red-shift of luminescence.In addition,CNQDs were applied in information encryption according to the“fluorescence-quenching-recovery”phenomenon.CNQDs-H₂O has been successfully applied to lysosomal imaging due of its good biocompatibility,low cytotoxicity,good photostability and specific recognition of lysosomes.Compared with the commercially available lysosomal fluorescent probe Lyso-Tracker Red,the CNQDs-H₂O probe exhibits superior light stability and is more suitable for long-term real-time imaging.