The Preparation Of Ionic Liquid Functionalized Fluorescent Carbon Nanomaterials By One-step Electrochemical Method And The Study Of Anion Detection

Fluorescent carbon nano materials,as a new type of fluorescent material,can be used in the fields of ion detection,biological imaging,energy conversion,catalysis and so on.It has many advantages,such as extensive raw materials,simple preparation methods,strong modification,excellent optical and electrical properties,catalytic properties and low toxicity.As an alternative to traditional fluorescent probes,fluorescent carbon nanomaterials have their unique advantages.For example,compared with organic fluorescent dyes,carbon nanomaterials have better optical stability.Compared with semiconductor fluorescent quantum dots,fluorescent carbon nanomaterials have lower toxicity and better chemical modification properties.Low dimensional fluorescent carbon nanomaterials,such as graphene quantum dots and carbon dots,have been widely studied in the field of metal ion detection.However,pure fluorescent carbon nanomaterials and inorganic anions have no obvious fluorescence response,it can not be directly applied to anion detection.Through the chemical modification of fluorescent carbon nanomaterials,the direct detection of anions has important research value.Based on the above findings,we use the graphite rods as the carbon source,ionic liquids as chemical modifier and supporting electrolyte.Through regulation the type of ionic liquids,three kinds of ionic liquid-carbon nanomaterials fluorescent compounds are prepared by one step electrochemical method.Their performance as fluorescent probes for direct detection of anions is also explored,respectively.As follows is idiographic research:?1?With cheap graphite as carbon source,heterogeneous mixed solution of non aqueous 1-butyl-3-methylimidazolium hexafluorophosphate?[BMIM]PF₆?and water as supporting electrolyte solution.Uniform size and high fluorescence intensity of ionic liquid-carbon nanoribbons?[BMIM]PF₆-CNRs?fluorescent composites are synthesized by one-step electrochemical stripping method.TEM is used to characterize its morphology,and found that it presents banded structure and good crystallinity.The [BMIM]PF₆-CNRs emit a strong blue fluorescence under the irradiation of ultraviolet lamp?365 nm?and the fluorescence quantum yield is 18.3%.The material has higher fluorescence intensity and photostability under acidic conditions.We investigate the interaction of the composites with different anions.It is found that the fluorescent composite could be selectively quenched by S^2-,and the S^2-could be detected according to the changes of fluorescence intensity of fluorescence probe induced by S^2-.The results show that the concentration of S^2-in the range of 0.1-300.0 ?M is linearly correlated with the percentage of fluorescence intensity quenching of fluorescence probe.The detection limit of S^2-is 85 n M?S/N = 3?,which can be used for sensitive and direct detection of S^2-ions.?2?With low cost graphite as carbon source,homogeneous mixed solution of aqueous 1-butyl-3-methylimidazolium tetrafluoroborate?[BMIM]BF₄?and water as supporting electrolyte solution.Uniform size,high fluorescence intensity,and good crystal structure of ionic liquid-carbon dots?[BMIM]BF₄-CDs?fluorescent composite materials are synthesized by one-step electrochemical stripping method.The structure and properties of synthesized carbon dots are characterized by transmission electron microscopy?TEM?,fourier transform infrared spectroscopy?FTIR?,X ray photoelectron spectroscopy?XPS?,fluorescence spectroscopy?FL?,and so on.The results show that the synthesized [BMIM]BF₄-CDs emit blue fluorescence,fluorescence quantum yield of 16.1%,and have good anti bleaching ability to ultraviolet light.Furthermore,[BMIM]BF₄-CDs have a good response to Fe?CN?₆^3-,for Fe?CN?₆^3-can quench its fluorescence.So,Fe?CN?₆^3-can be selective detected.The optimum p H condition and reaction kinetics of [BMIM]BF₄-CDs and Fe?CN?₆^3-are discussed,and established the method of quantitative detection of Fe?CN?₆^3-.The linear range of detecting Fe?CN?₆^3-is 1.0¹40.0 ?M and the detection limit is 30 n M?S/N = 3?.?3?With cheap graphite as carbon source,homogeneous mixed solution of aqueous 1-butyl-3-methylimidazolium bromide?[BMIM]Br?and water as supporting electrolyte solution,ionic liquid-carbon nanoparticles?[BMIM]Br-CNPs?fluorescent composites are prepared by one-step electrochemical stripping method.The synthesized [BMIM]Br-CNPs emit blue fluorescence,the fluorescence quantum yield of 16.9%,and have good light resistance.The effect of p H on the fluorescence intensity of [BMIM]Br-CNPs is investigated.It was found that the fluorescence intensity is the largest when p H was 4.Moreover,Cr₂O₇^2-can selectively quench the fluorescence of [BMIM]Br-CNPs.Therefore,the fluorescent probe can be used for Cr₂O₇^2-detection.The results show that the linear range of Cr₂O₇^2-is 5.0¹00.0 ?M and the detection limit is 66 n M?S/N = 3?.[BMIM]Br-CNPs are used for the detection of Cr₂O₇^2-in real water samples.The recovery rate is 93.05¹06.3% and the standard deviation?RSD?is less than 4%,indicated that the new fluorescent probe has a higher accuracy in the detection of Cr₂O₇^2-in real samples.