The Synthesis,characterization And Applications Of Doped Carbon Nanomaterials

Objective:The carbon dots?CDs?and graphite carbon nitride nanosheets?g-C₃N₄ nanosheets?,the new family member of carbon nanomaterials,have widely applied in heavy metal ion detection,drug carrier,fluorescent labeling,photocatalyst,biosensor and solar cell owing to easy preparation,large specific surface area,low toxicity and good biocompatibility etc.Currently,heteroatom?such as N,P,S,Ag,Fe?doped CDs and g-C₃N₄ nanosheets have been synthesized with high quantum yields,more stable optical properties,excellent catalytic performance and so on.Doped CDs and g-C₃N₄ nanosheets have been widely applied in biological imaging,environment detection and fluorescence tracer etc.Therefore,the synthesis of doped CDs and g-C₃N₄ nanosheets is meaningful.Methods:In this paper,nitrogen and sulfur co-doped carbon dots?NSCDs?,nitrogen and phosphorus co-doped carbon dots?NPCDs?were prepared by microwave assisted method,silver doped graphite carbon nitride nanosheets?Ag-g-C₃N₄ nanosheets?and phosphorous doped graphite carbon nitride nanosheets?p-g-C₃N₄ nanosheets?were fabricated by an ultrasonic exfoliating process.These four carbon nanomaterials were characterized by Transmission electron microscopy?TEM?,Fourier transform infrared spectrum?FT-IR?,X-ray diffraction?XRD?,X-ray photoelectron spectroscopy?XPS?,fluorescence spectroscopy and ultraviolet absorption spectroscopy.With the increasement of morin,the fluorescence of NSCDs was quenched,the method of detecting morin was successfully established.With the increase of the concentration of Hg²⁺,the fluorescence intensity of NPCDs reduce.Subsequently,with the addition of glutathione?GSH?,the fluorescence of NPCDs-Hg²⁺was restored.A“Turn off/on”fluorescence probe for the simultaneous detection of Hg²⁺and GSH was constructed.The fluorescence of Ag-g-C₃N₄ nanosheets was quenched dramatically with the addition of curcumin,the fluorescence probe detecting morin was established.With the increasement of Ag⁺,the fluorescence intensity of p-g-C₃N₄ nanosheets was decreased,a facile fluorescence method for detecting Ag⁺was fabricated.Results:The structures of NSCDs,NPCDs,Ag-g-C₃N₄ nanosheets and p-g-C₃N₄ nanosheets were characterized.The fluorescence of NSCDs can be effectively quench by morin,a method for the detection of morin was established.The detection limit was 47 nM with the linear range is 0.5³0.0?M.The method was applied to detect morin in human urine and blood samples with reoveries of 98.00%¹02.80%.Hg²⁺is able to quench the fluorescence of NPCDs and GSH recover the fluorescence of NPCDs-Hg²⁺system.So NPCDs as a“Turn off/on”fluorescence probe to detect of Hg²⁺and GSH was structured.The detection limit of Hg²⁺was 9.9 nM with the linear range of 0.01³0.0?M.The linear range of the NPCDs-Hg²⁺system for GSH was 0.5³2.0?M with the LOD of was11.2 nM.The reoveries of detecting Hg²⁺and GSH in biological samples were96.70%¹03.30%and 97.44%¹02.85%,respectively.Ag-g-C₃N₄ nanosheets as a sensitive fluorescence probe to detect curcumin was established.The detection limit of curcumin was 38 nM with the linear range of 0.01².0?M and the reoveries of detecting the curcumin in human urine and serum samples was 97.50%¹03.64%.Because the fluorescence of p-g-C₃N₄ nanosheets can be quenched by Ag⁺,a method for the detection of Ag⁺was builded.The LOD and linear range of Ag⁺were 2.1 nM and 0.02³.2?M.This method has been successfully applied for the detection of Ag⁺in tap and lake water samples with good reoveries of 96.87%¹03.75%.Conclusion:Based on morin can quench the fluorescence of NSCDs,a method of determining morin is established.The fluorescence quenching process between morin and NSCDs mainly was static quenching process.As a“Turn off/on”fluorescence probe,NPCDs can detected Hg²⁺and GSH in human urine and blood samples with a satisfied results.The fluorescence quenching process between Hg²⁺and NPCDs mainly was dynamic quenching process.With the addition of GSH,the fluorescence of NPCDs can be recovered owing to the combination of Hg²⁺and GSH by forming the Hg²⁺-S bond.A fluorescence probe based on Ag-g-C₃N₄ nanosheets has been developed for detercting curcumin and the method for p-g-C₃N₄ nanosheets to determining Ag⁺was finished,respectively.Static quenching is the main quenching mechanism between Ag-g-C₃N₄nanosheets and curcumin.The curcumin in the biological samples was determined by Ag-g-C₃N₄ nanosheets as a fluorescent probe with a satisfactory results.The fluorescence quenching process between p-g-C₃N₄ nanosheets and Ag⁺mainly was dynamic quenching process.The method has been applied to analyze Ag⁺in environmental water sample with satisfied results.