| With the rapid development of nanotechnology,nanomaterials play an increasingly important role in the fields of physics,chemistry.Quantum dots(QDs)are widely used in many fields such as drug delivery,biological/chemical sensors,photocatalysis,electronic devices due to their unique photoelectric properties such as broad absorption spectra,narrow emission spectra and excellent photostability field.According to the difference in solubility,QDs can be divided into hydrophobic QDs and hydrophilic QDs.Compared with hydrophobic QDs,the synthesis of hydrophilic QDs have the advantages of low equipment,environmental raw materials,and can be directly applied to biological systems without any modification,attracting researchers.In this system,the development of water-soluble QDs was described,functionalized chiral tunable CdSe QDs were synthesized by adopting chiral dual stabilizers and their chiral origins were discussed.For the first time,the synergistic effect of double reductants was used to synthesize silicon QDs(SiQDs)with quantum yield up to 84.92%.and the synergistic mechanism was preliminary analyzed.The yellow-green luminescent carbon dots(CDs)were synthesized by a one-step hydrothermal method and as a fluorescent probe successfully identified Fe2+.The first chapter mainly introduced the development of water-soluble QDs,including the introduction of QDs,the synthesis method of QDs,and the classification of water-soluble QDs.Followed by a detailed introduction of the development of chiral semiconductor QDs and their origins of chirality,the synthesis of SiQDs and its light-emitting mechanism.Finally,the synthesis of CDs and its application in the detection of metal ions were introduced.In the second chapter,chiral CdSe QDs were synthesized by one-step hydrothermal method using two thiol-based small molecules as ligands,which exhibited strong circular dichroism in the range of 200-475 nm.By selecting the combination of two chiral molecules with different structures and changing the molar ratio of two chiral molecules,the chiral activity of QDs could be finely tuned,and the chiral origin of the CdSe QDs could be explored to provide the synthesis of the chiral QDs.This chapter provided a new method for the synthesis of chiral QDs.The third chapter,this proof-of-concept study was the preparation of ultra-bright SiQDs with quantum yield of up to 84.92%based on the synergistic effect of two reductants(sodium citrate and thiourea),whilst N-aminoethyl-?-ami nopropyl trim ethoxy si lane as the silicon source.By applying a variety of reducing agent pairs to the synthesis of SiQDs,it was verified that the synergistic effect of the double reducing agents increases the universality of the quantum yields,and that the synergistic effect of specific double reducing agents could obtain long wavelength SiQDs.There is no significant difference in the particle size,surface groups and stability between the SiQDs prepared in this chapter and the SiQDs synthesized with the single reducing agent.The highly efficient and stable photoluminescence of SiQDs could lay a good foundation for their application as optical materials.In the fourth chapter,the green-emissioned CDs solution was synthesized by one-step hydrothermal method using DL-malic acid and ethylenediamine as raw materials.The effects of ethylene diamine input,reaction time and temperature on the fluorescence intensity of CDs were discussed,and selected the optimal synthesis conditions.UV-Visible absorption spectra,fluorescence spectra,infrared spectroscopy and X-ray energy spectrum analysis were used to study the optical properties,surface groups and elemental composition of CDs.As the CDs had good optical properties,they served as fluorescent probes and realized the identification of Fe2+ based on inner filter effect. |
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