| Due to its significant surface effect,quantum size effect ect,semiconductor quantum dots?QDs?,a type of nanocrystal with an average size of10 nm,had been widely applied on biomarker,ion-detecting agent,photovoltaic devices etc.In this thesis,by using heating reflux method under nitrogen protection,CdTe quantum dots,graphene/CdTe composites and silver doped graphene/CdTe composites with near-infrared luminescence properties in aqueous had been prepared,in which mercaptopropionic acid and mercapto graphene were used as stabilizers.CdTe quantum dots had been characterized by ultraviolet absorption spectroscopy,fluorescence emission spectroscopy,transmission electron microscopy,and X-ray photoelectron spectroscopy.Results showed that as prepared CdTe quantum dots with spherical morphology of2.7nm,had good dispersibility and good fluorescence emission.Graphene/CdTe quantum dot composites were characterized by transmission electron microscope,ultraviolet absorption spectrum,fluorescence emission spectrum,fluorescence decay curve and X-ray photoelectron spectroscopy.Results showed that graphene had been reduced during the preparing processes,and the fluorescence properties of CdTe quantum dots had been significantly improved after CdTe quantum dots was combined with graphene.In addition,the preparation and characterization of silver doped graphene/CdTe quantum dot composites with a fluorescence emission wavelength close to near infrared had been preliminary studied.Furthermore,graphene/CdTe composite materials,as prepared above,had been used as a luminescent substance for quantitative analysis of clenbuterol hydrochloride,brilliant blue,ponceau 4R and amaranth,respectively.Base on the formation of hydrogen bond between clenbuterol hydrochloride and graphene/CdTe quantum dots composites,graphene/CdTe quantum dots composites had been used for quantitative analysis of clenbuterol hydrochloride.The linear range was 7.22-108.30?mol·L-1,the limits of detection was 4?mol·L-1,and this method was applied for the detection of clenbuterol hydrochloride in actual samples.The spectral properties of the interaction between brilliant blue and graphene/CdTe quantum dot complexes had been investigated based on the strong fluorescence quenching effect of brilliant blue on graphene/CdTe quantum dots composites.Results showed that the UV absorption spectra of brilliant blue overlapped with the fluorescence emission spectrum of graphene/CdTe quantum dot composites,and the fluorescence emission intensity of brilliant blue increased with the decreasing of the fluorescence emission intensity of graphene/CdTe quantum dot composite,all those indicated that fluorescence resonance energy transfer between brilliant blue and graphene/CdTe quantum dot had been taken place.There was also a good linear relationship between the graphene/CdTe quantum dot composites fluorescence intensity reduction?F0/F?and the concentration of brilliant blue,this quenching system could be used for quantitative analysis of brilliant blue in solution.The linear range was 18.93-94.65nmol·L-1,and the limits of detection was 6.6 nmol·L-1.In addition,fluorescence and absorbance spectra were obtained to study the interaction between ponceau 4R/amaranth and graphene/CdTe quantum dots composites.Results showed that both ponceau 4R and amaranth had a strong fluorescence quenching effect on the graphene/CdTe quantum dot composites.Although both of them were static quenching processes,compared with amaranth,the ponceau 4R molecule had a higher conjugation degree,which had more significantly effect on the quenching of graphene/CdTe quantum dot.There was also a good linear relationship between the concentration of dyes?ponceau 4R and amaranth?and the decreasing of the fluorescence intensity?F0/F?of the graphene/CdTe quantum dot composites,and the limits of detection of ponceau 4R was 114.2 nmol·L-1,and the limits of detection of amaranth was 105.1 nmol·L-1. |
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