Ag/C (Silver/Carbon) hollow nano-sphere and preparation method thereof

A technology of hollow spheres and nanospheres, applied in the field of catalysis, can solve problems such as instability, easy aggregation, and easy oxidation, and achieve the effects of solving aggregation, improving activity and stability, and avoiding aggregation and oxidation

Active Publication Date: 2015-07-29
EAST EIGHT ENERGY (SHANGHAI) CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Noble metal catalysts, especially nano-noble metals with ultra-small size (1-10 nm), can greatly improve their catalytic performance due to the increase in specific surface area and the increase in the number of surface atoms. However, because of this, monodisperse ultra-small particles of nanoparticles With high surface energy, it is very easy to agglomerate, easy to oxidize, and cannot exist stably. Therefore, it is a very challenging task to prepare a stable single ultra-small nano-sized precious metal.

Method used

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  • Ag/C (Silver/Carbon) hollow nano-sphere and preparation method thereof
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  • Ag/C (Silver/Carbon) hollow nano-sphere and preparation method thereof

Examples

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Embodiment 1

[0018] Embodiment 1: In this embodiment, Ag / C nano hollow spheres are prepared by the hydrogen peroxide corrosion method, and the steps are as follows:

[0019] (1) Preparation of Ag / C nanospheres with core-shell structure by hydrothermal method: Dissolve 1 g of glucose in 20 ml of deionized water, add 0.5 ml of silver nitrate aqueous solution with a concentration of 0.1mol / L, disperse evenly, and transfer the solution to water In a thermal reaction kettle, hydrothermal reaction was carried out at 180°C for 4 hours; the reacted product was centrifuged to obtain Ag / C nanospheres with a core-shell structure; figure 1 A (SEM image) and 1B (TEM image) are shown. It can be clearly seen from the figure that the size of Ag / C nanospheres with core-shell structure is uniform, and the core-shell structure has good dispersion.

[0020] (2) Preparation of Ag / C hollow nanospheres: Disperse 50 mg of Ag / C nanospheres with a core-shell structure in 50 ml of deionized water, stir and disperse...

Embodiment 2

[0023] Example 2, this example studies the formation process of Ag / C nano hollow spheres.

[0024] h 2 o 2 It is a clean and efficient etchant, it can not only oxidize Ag to Ag + , and can also put Ag again + Reduction to smaller silver nanoparticles. In addition H 2 o 2 Generated O 2 Make the silver nanoparticles diffuse from inside to outside. Ag / C nanospheres with core-shell structure ( Figure 4 A) in H 2 o 2 The change process under the action of corrosion such as Figure 4 shown. After reacting for 10 minutes, the silver nucleus tended to be dissolved, and a small amount of dispersed silver nanoparticles with a particle size of about 10 nm formed in the carbon layer ( Figure 4 B). After 20 minutes of reaction, the silver core was partially dissolved, and a large number of silver nanoparticles were gradually formed in the carbon shell ( Figure 4 C). After 30 minutes of reaction, about half of the Ag core was dissolved, and a large number of smaller Ag nan...

Embodiment 3

[0025] Example 3, this example uses the Ag / C hollow nanospheres prepared in Example 1 for the catalytic hydrogenation of nitrophenol, specifically:

[0026]Steps: Prepare 0.5 M NaBH 4 (reducing agent, reduced p-nitrophenol) solution 2 ml and 0.01 M p-nitrophenol (4-NP) solution 1 ml. Sequentially add 200 μL of 0.5 M NaBH to a 50 ml beaker 4 Solution, 50 μL of 0.01 M p-nitrophenol (4-NP) solution and 20 ml of deionized water, after ultrasonic homogenization, take a sample for ultraviolet absorption test as a reference. Then 1.0 mg of Ag / C hollow nanospheres were added, under magnetic stirring at room temperature, samples were taken every 2-5 minutes, and UV absorption test was carried out after each sample was taken. Under the same conditions, the core-shell AgC microspheres were also tested for their catalytic performance as a reference.

[0027] like Figure 5 As shown in A, in NaBH 4 When no catalyst is added, there is a strong absorption peak at around 400 nm, which co...

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Abstract

The invention discloses an Ag/C (Silver/Carbon) hollow nano-sphere and a preparation method thereof, and belongs to the field of a catalysis technique. The preparation method comprises the following steps: taking an amorphous carbon ball as a carrier, uniformly mixing and stirring glucose and silver nitride, and reducing to obtain a uninuclear carbon-coated silver core-shell structure through a one step hydro thermal method; then, corroding the uninuclear carbon-coated silver core-shell structure through H2O2 (Hydrogen Peroxide), gradually changing a Ag core of which the size is about 100nm into nano-silver particles of which the sizes are smaller, diffusing the nano-silver particles to a carbon shell layer from inside to outside, and embedding the nano-silver particles into a carbon layer to leave a cavity; and obtaining the Ag/C hollow nano-sphere of the core-shell structure. The Ag/C hollow nano-sphere provided by the invention has the advantages of being capable of loading nano-scale catalyst granules in the amorphous hollow carbon ball, and preventing the aggregation and oxidation of the nano-catalyst; furthermore, a catalyst is simple in preparation process, high in activity and good in stability, thereby being extensively applied to the preparation of para-aminophenol by the catalytic hydrogenation of nitro-phenol.

Description

technical field [0001] The invention belongs to the technical field of catalysis, and in particular relates to an Ag / C nano hollow sphere and a preparation method thereof. Background technique [0002] Core-shell Ag / C nanoparticles are now attracting more and more research interest because these composite nanoparticles consist of different chemical compositions from the shell, which provides us with an opportunity to combine materials with unique properties. One possibility (Angew. Chem. Int. Ed. Vol. 43, pp. 597–601, 2004). This type of core-shell particles has received a lot of research due to its simple preparation, green and environmentally friendly preparation process, low biological toxicity, and easy modification of surface functional groups. [0003] Noble metal nanosilver has a wide range of applications in catalysis, and the yield and selectivity of noble metals as catalysts depend on the properties of their surfaces. Compared with bulk materials, nano-noble meta...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B22F9/24B22F1/02B01J23/50
Inventor 张龙飞董文钧李宝珍
Owner EAST EIGHT ENERGY (SHANGHAI) CO LTD
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