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CN-121991687-A - Titanium dioxide-quantum dot-silicon dioxide composite material with multilayer core-shell structure, and preparation method and application thereof

CN121991687ACN 121991687 ACN121991687 ACN 121991687ACN-121991687-A

Abstract

The invention discloses a titanium dioxide-quantum dot-silicon dioxide composite material with a multilayer core-shell structure, and a preparation method and application thereof. The core layer formed by titanium dioxide nano particles, the quantum dot intermediate layer adsorbed on the surface of the core layer through bridging of a silane coupling agent and the compact silicon dioxide shell layer wrapping the quantum dot intermediate layer are sequentially arranged from inside to outside. The method comprises the steps of introducing sulfhydryl into titanium dioxide nano-particles through silanization modification, obtaining water-soluble sulfhydryl quantum dots through ligand exchange by the quantum dots, forming a quantum dot-titanium dioxide compound through sulfhydryl interaction, and finally forming a silicon dioxide shell through hydrolytic condensation of a silicon source under a weak alkaline condition. The invention solves the problems of weak binding force, easy falling-off of the quantum dots and poor stability of the traditional quantum dot composite material by the 'core-functional layer-shell' collaborative design, and can be widely applied to the fields of photoelectric devices, photocatalytic materials and biological fluorescent markers.

Inventors

  • CHEN MINGJIE
  • SONG BOXIANG
  • SUN LEIMENG
  • LUO JIAJUN
  • JIANG BORUI

Assignees

  • 华中科技大学
  • 湖北光谷实验室

Dates

Publication Date
20260508
Application Date
20251226

Claims (10)

  1. 1. The titanium dioxide-quantum dot-silicon dioxide composite material with the multilayer core-shell structure is characterized by comprising the following structures from inside to outside: a core layer of titanium dioxide nanoparticles; The intermediate functional layer is a quantum dot bridged by a silane coupling agent and adsorbed on the surface of the core layer; and the shell layer is a compact silicon dioxide protective layer wrapped outside the quantum dot intermediate layer.
  2. 2. The multilayer core-shell structured titanium dioxide-quantum dot-silicon dioxide composite material according to claim 1, wherein the particle size of the titanium dioxide nanoparticles is 50-200 nm; The quantum dots are II-VI or IV-VI semiconductor quantum dots, and preferably one or more of CdSe, cdS, cdTe, pbS, znSe.
  3. 3. A method of preparing a composite material according to claim 1 or 2, comprising the steps of: S100, silanization modification of the surface of titanium dioxide: Dispersing titanium dioxide nano particles in a liquid solvent, performing ultrasonic dispersion until the system is uniform, regulating the pH of a reaction system by using acid, adding a silane coupling agent with a mercapto group at the tail end, reacting fully at room temperature under magnetic stirring, performing centrifugal separation, washing with methanol for multiple times, and drying under vacuum condition to obtain mercapto titanium dioxide; S200, quantum dot ligand exchange: dispersing the quantum dot with oleic acid as the original ligand in a liquid solvent, diluting to a specific concentration, adding an exchange ligand, magnetically stirring at room temperature for full reaction, centrifuging, removing supernatant, and washing the precipitate with absolute ethyl alcohol for multiple times to obtain the sulfhydrylation water-soluble quantum dot; s300, quantum dot adsorption: Dispersing the sulfhydrylation titanium dioxide obtained in the step S100 and the water-soluble sulfhydrylation quantum dot obtained in the step S200 in a liquid solvent together, stirring at room temperature for full reaction, then centrifugally separating, washing for a plurality of times by using the liquid solvent to remove unadsorbed quantum dots, and obtaining a quantum dot-titanium dioxide compound; s400, coating a silicon dioxide shell: Dispersing the quantum dot-titanium dioxide compound obtained in the step S300 in a liquid solvent, adding a silicon source, adjusting the pH of the system, hydrolyzing the silicon source under the weak alkaline condition, stirring at room temperature for full reaction, centrifuging, drying, and depositing on the surface to form a silicon dioxide shell, thereby obtaining the multi-layer core-shell structure composite material.
  4. 4. The method for preparing a multi-layer core-shell structured titanium dioxide-quantum dot-silicon dioxide composite material according to claim 3, wherein in S100, the silane coupling agent is gamma-mercaptopropyl trimethoxy silane, the reaction solvent is methanol, and the pH of the reaction system is 3-4.
  5. 5. The method for preparing a multi-layer core-shell structured titanium dioxide-quantum dot-silicon dioxide composite material according to claim 3, wherein in S200, the exchange ligand is 3-mercaptopropionic acid, and the reaction solvent is chloroform.
  6. 6. The method for preparing a multi-layer core-shell structured titania-quantum dot-silica composite material according to claim 3, wherein in S300, the solvent for the mixing reaction is chloroform.
  7. 7. The method for preparing a multi-layer core-shell structured titanium dioxide-quantum dot-silicon dioxide composite material according to claim 3, wherein in S400, the silicon source is methyl orthosilicate, the weakly alkaline condition is realized by adding ammonia water-ethanol solution, and the pH value is adjusted to 8-9.
  8. 8. The method for preparing a multi-layer core-shell structured titania-quantum dot-silica composite material according to claim 7, wherein in S400, the reaction solvent is chloroform.
  9. 9. The preparation method of the titanium dioxide-quantum dot-silicon dioxide composite material with the multilayer core-shell structure according to claim 3, wherein in S100, the mass ratio of the silane coupling agent to the titanium dioxide is 1 (2-4); In S400, methyl orthosilicate is used in an amount of 100-500. Mu.L per 15mL of solvent.
  10. 10. The use of a multilayer core-shell structured titania-quantum dot-silica composite according to claim 1 or 2, wherein the optoelectronic device is a quantum dot sensitized solar cell or a light emitting diode.

Description

Titanium dioxide-quantum dot-silicon dioxide composite material with multilayer core-shell structure, and preparation method and application thereof Technical Field The invention belongs to the technical field of nano composite materials, and particularly relates to a titanium dioxide-quantum dot-silicon dioxide composite material with a multilayer core-shell structure, and a preparation method and application thereof. Background As a novel nano photoactive material, the Quantum Dots (QDs) have excellent optical properties such as size-adjustable fluorescence emission characteristics, high quantum yield, wide absorption spectrum and the like, and have wide application prospects in the fields of photoelectrons, catalysis, biomedicine and the like. Among them, II-VI and IV-VI semiconductor quantum dots (such as CdSe, cdS, etc.) are becoming research hot spots due to their outstanding optical properties. Titanium dioxide [ ]) As a wide forbidden band semiconductor material, the material has good photocatalytic activity and electron transmission capacity, and is an ideal core material for constructing quantum dot sensitized solar cells and photocatalytic systems. The quantum dots and the titanium dioxide are compounded, so that the cooperative optimization of the optical performance and the electron transmission performance can be realized, but the existing compounding mode has the obvious technical defects that firstly, the quantum dots and the titanium dioxide are combined through physical adsorption or electrostatic action, the binding force is weak, the quantum dots are easy to fall off in the use process, secondly, the interface charge is seriously compounded, the overall performance of the material is influenced, thirdly, the quantum dots are easy to be corroded by water and oxygen when exposed to the environment, the phenomena of photo-bleaching, oxidization and the like occur, and the stability is extremely poor. Silicon dioxide [ ]) Has the characteristics of strong chemical inertia, good biocompatibility, adjustable structure and the like, and is often used as a coating protective layer to improve the stability of the material. At present, although the prior art has attempted to prepare quantum dot-titanium dioxide or quantum dot-silicon dioxide composite materials, a multilayer core-shell structure system with stable structure, high quantum dot loading rate and firm interface combination is not formed yet. The existing coating technology has the problems of insufficient shell compactness, harsh preparation conditions (high temperature and high pressure), poor universality and the like, and is difficult to meet the requirements of practical application on material performance. Therefore, developing a multilayer core-shell structure composite material with reasonable structural design, mild preparation process, excellent stability and firm quantum dot load becomes a technical problem to be solved in the field. Disclosure of Invention Aiming at the defects or improvement demands of the prior art, the invention provides a titanium dioxide-quantum dot-silicon dioxide composite material with a multilayer core-shell structure, and a preparation method and application thereof, and aims to solve the technical problems of weak binding force, easy falling-off of quantum dots and poor stability of the traditional quantum dot composite material. The composite material adopts the cooperative structural design of the titanium dioxide core-quantum dot intermediate layer-silicon dioxide shell, realizes the firm combination of the quantum dots and the titanium dioxide through the bridging action of the silane coupling agent and the strong interaction between sulfhydryl groups, and constructs a physical and chemical protective barrier by means of the compact silicon dioxide shell. Specifically, the silane coupling agent introduces mercapto functional groups on the surface of titanium dioxide, forms stable combination with mercapto quantum dots subjected to ligand exchange, thoroughly solves the problem of easy falling-off pain points of the quantum dots in the traditional composite mode, can effectively isolate corrosion of environmental factors such as water, oxygen and the like, inhibit photobleaching and oxidative degradation of the quantum dots, greatly improve the light stability and chemical stability of the material, simultaneously provides a good electron transmission channel for a titanium dioxide core, ensures that a quantum dot intermediate layer maintains excellent optical characteristics with adjustable size, complements the functions of the three, and realizes synchronous optimization of structural stability and optical performance of the material. To achieve the above object, according to a first aspect of the present invention, there is provided a titanium dioxide-quantum dot-silica composite material of a multilayer core-shell structure, which is composed of, from inside to outside: a core layer of tit