Studies On Preparation And Properties Of Fluorescent Sulfur Quantum Dots

Quantum dots(QDs)are attractive nanomaterials because of their size tunable photoluminescence,high quantum yield and high stability against photobleaching.They show great potential in solar energy conversion,photoelectric devices and fluorescent labeling.Among them,sulfur quantum dots(SQDs)as a new type of metal-free elemental quantum dots,because of its low toxicity,biocompatibility and chemical inertness,has gradually become the focus of research.The excellent properties of SQDs show great potential in many fields.This thesis takes SQDs as the research core,and conducts detailed experimental analysis and research around its preparation,performance and application.The detailed content is described as follows:(1)Based on S-EDA chemical method,sublimated sulfur was directly prepared into fluorescent SQDs by one-pot solvothermal treatment.The characterization results showed that SQDs have characteristics of uniform size distribution,good water solubility and stability,surface modifiable and low toxicity.Remarkably,the quantum yield of resulted SQDs and the corresponding conversion efficiency from S to SQDs were determined to be up to 87.8%and 26.3%,respectively,both of which are much higher than those reported previously.Then,the anti-counterfeiting fluorescent ink and fluorescent polymer composites were prepared.(2)The SQDs were used as a dual fluorescent probe for the detection of TNP and Cu²⁺.The SQDs fluorescence probe has good fluorescence response for the detection of TNP.The response time can reach 15 s and the detection limit is 63.8 n M.The SQDs as fluorescent test paper for the detection of TNP also showed a good detection effect.Meanwhile,the SQDs fluorescent probe also has good detection performance for Cu²⁺.When Cu²⁺coexists with other metal ions,it can still detect Cu²⁺sensitively.(3)By coating Cd S on the surface of SQDs,a kind of SQDs/Cd S core-shell QDs was prepared.The SQDs/Cd S core-shell QDs showed good fluorescence stability and optical properties in acid-base environment.By changing the reaction conditions,the emission peaks of SQDs/Cd S core-shell QDs can be tunable in the blue to red band(473 nm-610 nm).Then,SQDs/Cd S core-shell QDs were mixed with polyvinyl alcohol to prepare fluorescent polymer nanocomposites.