| Carbon nanodots（C-dots）are a class of carbon-based fluorescent nanomaterials with particle size less than 10 nm and containing various functional groups or organic polymers.Because of its unique merits,such as excellent light stability,biocompatibility,simple and low-cost preparation,C-dots have been widely used in sensing,bio-imaging,optoelectronic devices,catalysis.However,the preparation,structure and luminescence mechanism of C-dots are still controversial,which severely limit the development and applications of C-dots.Based on these,the main research contents of this paper are as follows:（1）C-dots with a large amount oxygen-containing functional groups（-COOH,-C=O,-OH）on the surface were prepared by chemical oxidation of carbon fibers by H2SO4 and HNO3（volume ratio=1:2）.Herein,the effect of electron donor-acceptor distance(r DA)on the electron tranfer rate was investigated based on the photoluminescence（PL）quenching of C-dots by naphthoquinone（NQ）.In order to fix NQ’s position and orientation,β-cyclodextrin（β-CD）with a host-guest recognition ability was introduced to include NQ in a ratio of 1:1,and r DA was changed by the linkage length between C-dots andβ-CD.Aminocyclodextrins（NH2-β-CD）were obtained by the monosubstitution of theβ-CD’s 6thhydroxyl group with amino-terminals alkane（NH2-（CH2CH2）n-NH2,n=1,3,6）.The carboxyl groups on C-dots and the amino groups of NH2-β-CD were coupled to obtain different linkage-length C-dots-Cyclodextrins（C-dots-β-CD）.According to the experimental results,photoinduced electron transfer（PET）process from the excited C-dots-β-CD to NQ led to the fluorescence quenching,and the electron transfer rate of C-dots-β-CD/NQ system decreased as the linkage length increased.This work described the PL quenching kinetic process of C-dots-β-CD/NQ in detail,and quantified the distance-dependent PET process,which is important for the design of efficient fluorescent probes and light energy conversion devices.（2）C-dots-EDA-CD was obtained by modifying C-dots with mono-ethylenediamined cyclodextrin（EDA-β-CD）.C-dots-EDA-CD as the main luminophore and potassium perfluoride（K2S2O8）as the co-reactant were used to detect ultra-micro bisphenol A（BPA）in water by electroluminescence.The optimal experimental conditions were that C-dots-EDA-CD（3.33μg/m L）dispersed in a p H 9 BR buffer containing 0.125 M K2S2O8,and scanning rate was 100 m V/s.Results data showed that the ECL intensity and BPA concentration had a good linear in the range of 3.33～33.33 n M,and the detection limit was203 p M.The method had the advantages of low toxicity,low cost,environmental friendliness,and it achieved excellent detection sensitivity.This work is important for the construction of C-dots-based electroluminescence sensors. |
