基于玉米淀粉制备绿色碳量子点及氢离子/氢氧根离子调节荧光开关性能

以玉米淀粉为碳源,在草酸的作用下利用乙醇溶剂热法制备了一种绿色荧光碳量子点(G-CQDs)。通过透射电子显微镜(TEM)、傅里叶红外光谱(FT-IR)、X射线衍射(XRD)、X射线光电子能谱(XPS)和Raman光谱等测试分析了G-CQDs的形貌、组成和结构。结果表明,G-CQDs为粒径为2~5 nm的准球形纳米颗粒,表面含有丰富的C—O、O—H等亲水性基团;且具有类石墨烯结构。荧光测试结果表明,合成的G-CQDs在385 nm的光激发下在~520 nm处呈现明显的荧光发射,且发射强度随着G-CQDs浓度的降低呈现先增大后降低的趋势,其荧光量子产率可达38.5%。此外,G-CQDs的荧光发射强度随着溶液H+和OH-的浓度变化表现出明显不同的淬灭行为,并可用于溶液中H+和OH-的可逆关-开“off-on”型荧光响应探针。

Preparation of Green Carbon Quantum Dots from Corn Starch and Hydrogen Ion/Hydroxyl Ion Regulated Fluorescent Switch Performance

Green fluorescent carbon quantum dots(G-CQDs)were synthesized from corn starch and oxalic acid via an ethanol solvothermal method.The morphology,composition and structure of G-CQDs were analyzed using transmission electron microscopy(TEM),Fourier transform infrared spectrometer(FT-IR),X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS)and Raman spectroscopy.The results show that G-CQDs are quasi-spherical nanoparticles with the particle size of about 2~5 nm and have graphene-like structure with abundant water-soluble groups such as C—O and O—H on the surface.The fluorescence measurement assay results exhibit that the synthesized G-CQDs display strong fluorescence emission at~520 nm with the excitation wavelength of 385 nm,and the emission intensity increases first and then decreases with the decrease of the concentration of G-CQDs.The fluorescence quantum yield of the synthesized G-CQDs can reach up to 38.5%.Moreover,the fluorescence emission of G-CQDs exhibits various decay behaviors with the varied concentration of H^+ and OH^-.Therefore,the synthesized G-CQDs can be utilized as the reversible“off-on”switch probe for the detection of H^+ and OH^-.