Synthesis And Applications Of Novel Carbon Nanodots

Photoluminescence nanomaterials have attracted the attentions of the researchers widely due to their versatile applications in many fields.However,high-performance quantum dots are usually composed of toxic heavy metal elements,which limit their applications in the medical field.Therefore,it is of great significance to develop a novel low toxicity photoluminescent nanomaterial instead of metal carbon quantum dots.Since the carbon nanodots were first discovered in 2004,many researchers have payed their attentions to achieve better synthesis route,increase the photoluminescence(PL)quantum yield(QY),explore the physical and chemical properties of carbon nanodots and develop their applications.Chapter 1: The synthetic methods,characteristic of carbon nanodots and their application researches are reviewed.Chapter 2: Novel carbon nanonanodots were synthesized using grape skin by one pot hydrothermal method and the experimental conditions were optimized.The carbon nanonanodots were characterized by TEM,fluorescence,UV,IR and XPS.The size of carbon nanodots is 4.0±1.5 nm.The carbon nanonanodots showed green fluorescence which optimal excitation wavelength was 430 nm,and the corresponding emission wavelength was 522 nm,with the excitation wavelength dependence,which quantum yield was 0.19,and the stability and anti-photobleaching were perfect.Picric acid could quench the fluorescence of the carbon nanonanodots solution in the phosphate buffer solution with pH = 7.4,so a method to detect picric acid was established with high sensitivity,good selectivity and anti-interference ability.The linear range was 0.06-79.4 ?M and the detection limit was 10 nM(S / N = 3).This method was used to detect of actual water samples.Chapter 3: Carbon nanonanodots(CDs)were synthesized by one step hydrothermal treatment using Sophora flavescens Ait as carbon source at optimized experimental conditions.Then CDs were characterized by TEM,fluorescence,UV,IR and XPS,which possess high quantum yield(0.35).The CDs were stable in aqueous solutions and have high photochemical stability,oxidation resistance.The fluorescence of CDs was quenched by chromium(VI)in phosphate buffer solution of pH=6.0,and the method of the determination of chromium(VI)was founded,which had a linear relation in the range of 0.06-40 ?M and the detection limitation was 20 nM.The method was used for the detection of chromium(VI)in real water samples.Moreover,based on the redox mechanism,after the addition of AA,the fluorescence intensity of CDs and chromium(VI)was recovered obviously,and the increase content of fluorescence and the concentration of AA had a linear relation in the range of 0.1-4.0 mM and the detection limitation was 80 ?M,which could be used to detect the content of AA in real samples.Therefore,the CDs could behavior as a good fluorescent probe to be applied in successful detection of Cr(VI)and AA based on ‘‘on-off-on” mechanism.Chapter 4: Carbon nanonanodots(CDs)were synthesized by one step hydrothermal treatment using Eucommia ulmoides leaf as carbon source at optimized experimental conditions.The size of carbon nanodots is 3.55±1.45 nm and the fluorescence quantum yield was 0.42.The carbon nanonanodots were characterized by TEM,fluorescence,UV and IR.In phosphate buffer solution of pH=6.0,the fluorescence intensity of carbon dot could increase with increasing the concentration of aluminum ions.Based on the relationship of carbon dots and aluminum ion,the detection method of aluminum ion was established,which had a linear relation in the range of0.01-2.5 mM and the detection limitation was 23 nM,this method had high sensitivity,low detection limit,fast response(10 s)and was used to detect of actual water samples.Chapter 5: We summarized the research results of this paper and prospected the follow-up work.