Preparation Of Multi-color Doped Carbon Dots And Their Application Research

Because of its good biocompatibility,easy preparation,high quantum yield,broad and flexible adjustable emission spectrum,carbon dots(CDs)have great potential in many fields such as biomedicine,photoelectric lighting,energy storage,chemical analysis,etc.,and are widely studied by scientists and their industries in various countries.Developing multi-color CDs to provide technical support for full-color HD real-time imaging,flexible quantum dot display and warm white LED light source applications is one of the important directions of current CDs.To this end,this thesis explores and optimizes the synthesis process and color modulation techniques the basis of previous studies,using doping means to synthesize CDs with a single precursor,achieves the synthesis of single-element(N)and two-element(S,N)co-doped multiple fluorescence-emitting CDs with a single precursor,respectively,then we explored the applications of multicolor CDs for chemical sensing and white LED light sources.The details are as follows:(1)Using N-methyl-pyrrolidone(NMP)as the single C,N source,blue fluorescent N-CDs were synthesized by the reaction of NMP and hydrogen peroxide under high temperature and pressure conditions in a reactor.The synthesized N-CDs not only have high N content,but also the quantum yields of the synthesized CDs were greatly improved by the modification of the preparation method.The synthesized N-CDs were then characterized by multiple means and their application in the naked-eye detection of Fe³⁺and F^-was explored,with detection limit(LOD)Fe³⁺66 n M and F^-59 n M,respectively.(2)Mono-doped red fluorescent N-CDs were formed by self-condensation dehydration carbonization of 1,5-diamino-4,8-dihydroxy-9,10-anthracenedione(DDAQ)catalyzed by concentrated sulfuric acid under hydrothermal conditions using(DDAQ)as a single precursor.A colorimetric/fluorescent dual-mode sensor was constructed based on the synthetic N-CDs and used for the visual detection of Fe³⁺and glyphosate,with the detection limit(LOD)were 34 n M(fluorescence)and 92 n M(colorimetric)for LOD(Fe³⁺)and 8 n M(fluorescence)and 94 n M(colorimetric)for LOD(glyphosate),and the recoveries were98.5%?106.4%(fluorescence)and 97.2%?108.6%(colorimetric)for Fe³⁺and100.3%?113.1%(fluorescence)and 97.9%?108.5%(colorimetric)for glyphosate,respectively.)and 97.9%?108.5%(colorimetric).The prepared CDs have good biocompatibility and can be used as a fluorescent probe for the detection of intracellular Fe³⁺.(3)In this subsection,2,5-diaminobenzenesulfonic acid as the single precursor source to synthesize blue,green,and red tri-primary fluorescent S,N-doped CDs,simply by changing the solvent type(formamide,NMP,DMF)in the hydrothermal process,and then we explored the applications of the three synthesized CDs in trace detection and light source modulation.The detection limits up to LOD(Ag⁺)=35 n M and LOD(Fe³⁺)=23 n M,respectively,and the CIE(1931)coordinates of the CDs with white light obtained by mixing the three prepared CDs were up to(0.32,0.33),which is nearly pure white light emission.