Preparation And Environmental Applications Of Functional Carbon Dots Materials

Carbon dots?CDs?have become the focus by researchers as innocuity,stability,environmental friendliness,good biocompatibility,excellent optical properties,various preparation methods,controllable functions,simple preparation etc.In this case,different functional carbon dots could be used in different environmental issues by controlled the structure and optical properties.Specifically,there are three aspects introduced in detail in the following paragraphes.In chapter II,a polymer carbon dots/quantum dots dual-emssion composite nanoparticle has been prepared via self-assembly method.The polymer carbon dots possess amphiphilic property due to the functional group structure of polymer.Meanwhile,the optical properties of two kinds of fluorescent nanoparticles can be retained by the emulsion ultrasonic self-assembly method,so that the synthesized composite nanoparticles have dual-emission fluorescence properties.The composite material possesses high sensitivity and selectivity with Hg²⁺,with the increasing of the concentration of Hg²⁺,compared with the traditional detection application of single nanoparticle,composite nanoparticles are lower detection limit,more sensitive.And the changes of luminescence color could be found by naked eyes in different concentration of Hg²⁺in water,which makes water heavy metal detection is more effective and convenient.In chapter III,we show that the white light emission fluorescence property by controlled structure and surface groups of CDs,and application in the field of LED.Because of the fluorescence emission different mechanisms in carbon dots,and different functional groups on the surface,poly 1-eighteen olefin/maleic acid?PMAO?and o-phenylenediamine?OPD?were prepared for CDs,and the products were dialysis,column chromatography method for purification.Through the spectrum,the CDs have a full cover on the visible spectrum,and the white light fluorescence emission was observed under the ultraviolet lamp.Subsequently,the CDs were used as the optical conversion layer by GaN chip to achieve the preparation of white LED devices.In chapter IV,photocatalyst functional CDs were prepared to degrade antibiotic pollutants in the field.Because the traditional P25 photocatalytic materials as photocatalysts have wide band gap?3.2 eV?,so that the material of the absorption of visible light using less.Therefore,in order to make CDs could be used as photocataltic materials under visible light conditions,p-nitrobenzoic acid and p-phenylenediamine with large conjugated structure and nitro functional groups were prepared for CDs.The product was purificated by freeze-dried treatment.The biodegradable antibiotic pollutants represented by oxytetracycline were studied under the condition of simulated visible light,and the photocatalytic degradation performance was studied by CDs.After 90 minutes irradiated under visible light,the degradation rate of pollutants can reach 95%.In summary,we prepared different functional CDs to solve the different environmental problems.Compared with the traditional fluorescence nanoparticle,composite nanoparticles could be more effective in detecting water in Hg2+.CDs could be realized in white light emission LEDs with different surface groups.Also CDs could be used in the photocatalytic degradation of antibiotics.With the deep study of CDs,CDs with different functional properties could be widely used in the environmental field.