Method for preparing silica / silver flower-shaped core-shell structure particles by formaldehyde reduction method

A technology of silica and core-shell structure, applied in the direction of nanostructure manufacturing, nanotechnology, nanotechnology, etc., to achieve good dispersion and enhance the effect of dye luminescence

Inactive Publication Date: 2010-07-07
ZHEJIANG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Most studies have focused on the effects of surfactants, temperature, and additives on particle morphology, and some theories such as soft templates and selective adsorption of surfa...

Method used

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  • Method for preparing silica / silver flower-shaped core-shell structure particles by formaldehyde reduction method
  • Method for preparing silica / silver flower-shaped core-shell structure particles by formaldehyde reduction method
  • Method for preparing silica / silver flower-shaped core-shell structure particles by formaldehyde reduction method

Examples

Experimental program
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Effect test

Embodiment 1

[0017] Add 0.1 g of silica spheres with a diameter of 300 nm to 10 ml of water for ultrasonic dispersion for 20 minutes, add to 10 ml of 3% SnCl 2 2H 2 O in a dilute hydrochloric acid solution (add 100 microliters of 37% concentrated hydrochloric acid) and stir for 30 minutes, centrifuge and wash with deionized water 5 times, and disperse into 5 milliliters of water. Under ultrasonic conditions, add the sphere solution to 15 ml of 0.35 mol / L silver ammonia solution and react for 20 minutes. A layer of small silver particles grow on the surface of the silica sphere. Centrifuge with deionized water and disperse into 10 ml of ethanol . Add 0.1 ml of silica sphere solution with small silver particles on the surface to 200 ml of water, add 0.5 ml of 1 mol / liter silver nitrate aqueous solution, then add 0.2 ml of formaldehyde, 0.4 ml of ammonia water, and then add 20 ml of 5% PVP The aqueous solution was stirred, reacted for 2 hours, and cleaned by centrifugal deposition with deio...

Embodiment 2

[0022] Add 0.1 g of silica spheres with a diameter of 100 nm to 10 ml of water for ultrasonic dispersion for 20 minutes, add to 10 ml of 3% SnCl 2 2H 2 O in a dilute hydrochloric acid solution (add 100 microliters of 37% concentrated hydrochloric acid) and stir for 30 minutes, centrifuge and wash with deionized water 5 times, and disperse into 5 milliliters of water. Under ultrasonic conditions, add the sphere solution to 15 ml of 0.35 mol / L silver ammonia solution and react for 20 minutes. A layer of small silver particles grow on the surface of the silica sphere. Centrifuge with deionized water and disperse into 10 ml of ethanol . Add 0.1 ml of silica sphere solution with small silver particles on the surface to 200 ml of water, add 0.5 ml of 1 mol / liter silver nitrate aqueous solution, then add 0.2 ml of formaldehyde, 0.4 ml of ammonia water, and then add 20 ml of 5% PVP The aqueous solution was stirred, reacted for 2 hours, and cleaned by centrifugal deposition with deio...

Embodiment 3

[0024] Add 0.1 g of silica spheres with a diameter of 1000 nm to 10 ml of water for ultrasonic dispersion for 20 minutes, add to 10 ml of 3% SnCl 2 2H 2 O in a dilute hydrochloric acid solution (add 100 microliters of 37% concentrated hydrochloric acid) and stir for 30 minutes, centrifuge and wash with deionized water 5 times, and disperse into 5 milliliters of water. Under ultrasonic conditions, add the sphere solution to 15 ml of 0.35 mol / L silver ammonia solution and react for 20 minutes. A layer of small silver particles grow on the surface of the silica sphere. Centrifuge with deionized water and disperse into 10 ml of ethanol . Add 0.1 ml of silica sphere solution with small silver particles on the surface to 200 ml of water, add 0.5 ml of 1 mol / liter silver nitrate aqueous solution, then add 0.2 ml of formaldehyde, 0.4 ml of ammonia water, and then add 20 ml of 5% PVP The aqueous solution was stirred, reacted for 2 hours, and cleaned by centrifugal deposition with dei...

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Abstract

The invention discloses a method for preparing silica / silver flower-shaped core-shell structure particles by formaldehyde reduction method, which adopts the nucleation-regrowth two-step growth process by the rapid growth of formaldehyde reaction, and comprises the following steps: 1) preparing sub-micron silica balls the surfaces of which absorb silver nanoparticles; 2) dispersing the silica balls obtained from the step 1) in water, reducing silver nitrate with formaldehyde under the catalysis of ammonia, and then adding the aqueous solution of polyvinylpyrrolidone and reacting by stirring; and 3) washing a reaction liquid by centrifuging and then dispersing the reaction liquid in water to obtain the colloidal solution of the silica / silver flower-shaped core-shell structure particles. The method of the invention has simple and controllable process and good monodispersity of products, and the silver in the particles has a face-centered cubic and close-packed hexagonal coexisted unique crystal structure; and the flower-shaped silver core-shell particles have greater specific surface area and roughness, and great amount of hot spots exist in the particles.

Description

technical field [0001] The invention relates to a method for preparing silicon dioxide / silica-like core-shell structure particles, belonging to the field of photonic materials. Background technique [0002] Noble metal (such as gold, silver, platinum) micro-nano particles have surface plasmon resonance properties, and their plasmon resonance properties vary with particle size and shape. The plasmon resonance characteristics of metal particles lead to a great enhancement of the local electromagnetic field near the particles. This enhanced local field enhances the luminous intensity of the luminous body near the noble metal particles, which can greatly increase the Raman scattering intensity of the molecules near the particles. Noble metal particles are also used to catalyze many chemical reactions. These applications are all related to the roughness of the particle surface. And recently some scholars have pointed out that the enhancement effect can be significantly improved...

Claims

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Application Information

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IPC IPC(8): B22F9/24B82B3/00
Inventor 李东升刘涛杨德仁
Owner ZHEJIANG UNIV
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