Preparation Of Heteroatom-doped Carbon Dots And Its Application In Environmental Analysis

As one of the most promising functional nanomaterials,carbon dots（CDs）have been widely used in the fields of analytical detection,biological imaging,photoelectrocatalysis,environmental monitoring and drug analysis due to their excellent water solubility,high light stability and good biocompatibility.In this paper,three novel fluorescent CDs doped with different heteroatoms were prepared by one-step solvothermal method,and their morphologies,structures and photochemical properties were characterized.And the prepared fluorescent CDs were used in the field of environmental monitoring.The main research results are as follows:1.BluefluorescentN,S-CDswerepreparedusing1-nitroso-2-naphthol-3,6-disulfonic acid and 1,2-ethylenediamine as precursors by one-step hydrothermal method.The particle size of N,S-CDs is about 10.31nm,and the optimal excitation and emission wavelength are 378nm and 468 nm,respectively.And the fluorescence quantum yield（QY）is about 3.0%.Based on the internal filtering effect of Cr⁶⁺,the N,S-CDs,an"on-off"fluorescence sensing method for Cr⁶⁺,was developed.Two linear ranges for detection Cr⁶⁺are 2-100μM and 100-330μM,and two corresponding detection limits（LOD）are 68.23 n M and 206 n M,respectively.2.A green fluorescent N,S-CDs were prepared by one-step hydrothermal method using 1,4-phenylene diisocyanate as carbon source and dimethyl sulfoxide as solution.The particle size of N,S-CDs is about 13.2 nm.The optimal excitation and emission wavelength of N,S-CDs are 362 nm and503 nm,respectively.And the fluorescence quantum yield is 7.0%.Based on the high selectivity and excellent anti-interference performance of N,S-CDs for Cr⁶⁺,a label free Cr⁶⁺fluorescent probe was established.The linear range and detection limit were 4-956μM and 30 n M,respectively.The concentrations of Cr⁶⁺in tap water and lake water were successfully detected.3.Using 1,4-Phenylene diisocyanate,N,N-dimethylformamide and ammonium hydroxide as precursors,orange red fluorescent N-doped CDs（N-CDs）were synthesized by one-step solvothermal method.The particle size of N-CDs is about 8.77 nm,and the optimal excitation and emission peaks are 483 nm and 587 nm,respectively.Due to the electron transfer effect between Cu²⁺and N-CDs,Cu²⁺can effectively quench the fluorescence of N-CDs.Therefore,a novel Cu²⁺fluorescence probe with a linear range of20～250μM was established and successfully applied to the determination of Cu²⁺in actual water samples.