阅读说明：本技术 一种中心放射状-双孔纳米复合材料的制备方法及其应用 (Preparation method and application of central radial-diplopore nano composite material ) 是由 张其清 敖丽娇 于 2020-11-30 设计创作，主要内容包括：本发明涉及纳米材料技术领域,具体涉及一种中心放射状-双孔纳米复合材料的制备方法及其应用,其中中心放射状-双孔纳米复合材料的制备方法,包括如下步骤,S1：TEOS以CTAB和NaSal为结构导向剂,采用阴离子辅助法制备树状介孔SiO-2微球；S2：以树状介孔SiO-2微球为亲和模板,加入Fe(acac)-3及PEI通过高温热解法一步合成树状介孔SiO-2/Fe-3O-4复合载体；S3：加入金离子通过氨基与金离子螯合获得金种子,向金种子中加入还原剂得到金颗粒；S4：通过表面活性剂模板化途径在整个载体表面包裹一层介孔二氧化硅；本发明采用放射状大孔径的树状硅作为模板,依次组装上超顺磁四氧化三铁,金纳米颗粒,继而在其表面包上一层介孔硅,实现有保护层的可持续及可回收利用的双孔催化剂。(The invention relates to the technical field of nano materials, in particular to a preparation method and application of a central radial-double-hole nano composite material, wherein the preparation method of the central radial-double-hole nano composite material comprises the following steps of S1: TEOS (tetraethyl orthosilicate) takes CTAB (cetyltrimethyl ammonium bromide) and NaSal (sodium salicyl) as structure directing agents, and adopts an anion-assisted method to prepare dendritic mesoporous SiO 2 Microspheres; s2: with tree-shaped mesoporous SiO 2 The microspheres are used as affinity templates, and Fe (acac) is added 3 And one-step synthesis of dendriform mesoporous SiO by PEI through high-temperature pyrolysis 2 /Fe 3 O 4 A composite carrier; s3: adding gold ions, chelating amino groups with the gold ions to obtain gold seeds, and adding a reducing agent into the gold seeds to obtain gold particles; s4: coating a layer of mesoporous silica on the surface of the whole carrier through a surfactant templating way; the invention adopts radial macroporous tree-shaped silicon as a template, sequentially assembles superparamagnetic ferroferric oxide and gold nanoparticles, and then coats a layer of mesoporous silicon on the surface of the gold nanoparticles, thereby realizing a sustainable and recyclable double-pore catalyst with a protective layer.)

1. A preparation method of a central radial-diplopore nano composite material is characterized by comprising the following steps:

s1: TEOS (tetraethyl orthosilicate) takes CTAB (cetyltrimethyl ammonium bromide) and NaSal (sodium salicyl) as structure directing agents, and adopts an anion-assisted method to prepare dendritic mesoporous SiO₂Microspheres;

s2: with tree-shaped mesoporous SiO₂The microspheres are used as affinity templates, and Fe (acac) is added₃And one-step synthesis of dendriform mesoporous SiO by PEI through high-temperature pyrolysis₂/Fe₃O₄A composite carrier;

s3: adding gold ions, chelating amino groups with the gold ions to obtain gold seeds, and adding a reducing agent into the gold seeds to obtain gold particles;

s4: coating a layer of mesoporous silica on the surface of the whole carrier through a surfactant templating way.

2. The method of claim 1, wherein the step S1 is as follows:

s1.1: adding TEA into water, heating, stirring and mixing;

s1.2: adding CTAB and NaSal into the TEA mixed solution for reaction;

s1.3: adding TEOS into the reaction solution, and keeping the reaction solution at 80 ℃ for 2-6 h;

s1.4: centrifuging the product and washing with ethanol;

s1.5: heating the obtained precipitate in a mixed solution of hydrochloric acid and methanol for reaction, and removing the residual organic template in the pore channel;

s1.6: washing the product with the organic template removed with ethanol to obtain the arborescent mesoporous SiO₂And (3) microspheres.

3. The method of claim 2, wherein the step S1.5 is repeated 2-3 times.

4. The method of claim 2, wherein the step S2 is as follows:

s2.1: making tree-shaped mesoporous SiO₂Centrifuging the ethanol solution of microspheres to obtain wet precipitate, and mixing the wet precipitate with Fe (acac)₃Adding PEI into TEG and performing ultrasonic dispersion;

s2.2: heating the mixed solution subjected to ultrasonic dispersion under a vacuum condition to remove ethanol;

s2.3: heating and stirring the mixed solution without the ethanol in the nitrogen atmosphere to react;

s2.4: when the temperature of the solution is cooled to room temperature, adding acetone with the same volume, and separating by using a magnet to obtain a product;

s2.5: washing the product with ethanol to obtain the dendriform mesoporous SiO₂/Fe₃O₄And (3) a composite carrier.

5. The method for preparing a radial-centered nanoporous nanocomposite material according to claim 4, wherein the temperature of S2.3 is increased to 210 ℃ under the nitrogen atmosphere, and the reaction is carried out for 2 hours with stirring; then the temperature is increased to 290 ℃, and the stirring reaction is continued for 1 h.

6. The method of claim 4, wherein the step S3 is as follows:

s3.1: to HAuCl₄Adding K into the solution₂CO₃Solution of Au³⁺Reduction to Au⁺；

S3.2: under ice bath, tree-shaped mesoporous SiO₂/Fe₃O₄Adding Au into the aqueous solution⁺Carrying out reaction on the solution;

s3.3: under vigorous stirring, the newly prepared NaBH is rapidly added to the reacted liquid₄Solution, the solution turns red;

s3.4: removing free gold particles through magnetic separation to obtain the tree-shaped mesoporous SiO₂/Fe₃O₄Dispersing Au seeds into water;

s3.5: to HAuCl₄Adding K into the solution₂CO₃The solution reacts, and the solution becomes colorless;

s3.6: adding tree-shaped mesoporous SiO into the colorless solution₂/Fe₃O₄Mixing Au seed solution with stirring;

s3.6: firstly adding PVP into the mixed solution for stirring and mixing, then slowly adding hydroxylamine hydrochloride solution for reaction, and centrifugally washing a reaction product to obtain the dendriform mesoporous SiO₂/Fe₃O₄/Au。

7. The method of claim 6, wherein the step S4 is as follows:

s4.1: taking tree-shaped mesoporous SiO₂/Fe₃O₄Au is dissolved in CTAB solution, NaOH and TEOS are added for reaction, and the reaction product is centrifugally washed to obtain the dendriform mesoporous SiO₂/Fe₃O₄/Au/mSi。

8. Use of a central radial-bimodal nanocomposite material obtained according to any one of claims 1 to 7, in the recycling catalysis of p-nitrophenol.

Technical Field

The invention relates to the technical field of nano materials, in particular to a preparation method and application of a central radial-double-hole nano composite material.

Background

The multifunctional nano-carrier has larger specific surface area and porosity, adjustable pore size, easily modified inner/outer surface and colloid stability, so that the multifunctional nano-carrier has important application in the biomedical fields of biosensing, bioimaging, biocatalysis, drug delivery and the like. In recent years, compared with the traditional mesoporous silicon (such as MCM-41 or SBA-15 and the like), the dendritic mesoporous silica is a novel porous carrier, and the unique central radial pore channel of the dendritic mesoporous silica is beneficial to the full contact between the interior of the pore channel and guest molecules so as to improve the loading efficiency. The mesoporous silicon is compounded with magnetic nano particles, noble metal nano materials and the like, and the unique properties of optical, electric, magnetic and the like of inorganic functionalized nano elements are utilized to endow the carrier with more performances. Compared with the common polystyrene microspheres, the polystyrene microspheres have larger specific surface area, and can realize uniform filling of nanoparticles from inside to outside. Meanwhile, the nano-carrier has high optical transparency, is easy to synthesize and control the size, and can be subjected to various surface silanization modifications, so the nano-carrier is an excellent nano-carrier. Such large-pore-diameter dendriform SiO₂Has incomparable advantages in the aspects of loading and delivering macromolecules such as protein, enzyme, antibody, nucleic acid and the like.

Existing large-aperture tree-shaped SiO₂When the pore diameter of the template carrying the noble metal is too small, the template with the hollow large pore diameter needs to be obtained by adopting complicated steps such as a physical or chemical method and the like; the noble metal used for catalysis does not have a good protective layer, and is easy to agglomerate or inactivate when reacting with the outside, so that the catalytic efficiency is reduced.

Disclosure of Invention

Aiming at the problems, the invention aims to provide a preparation method and application of a central radial-double-hole nano composite material.

In order to achieve the purpose, the invention is realized by the following technical scheme:

a preparation method of a central radial-diplopore nano composite material comprises the following steps:

s1: TEOS (tetraethyl orthosilicate) takes CTAB (cetyl trimethyl ammonium bromide) and NaSal (sodium salicylate) as structure-directing agents, and adopts an anion-assisted method to prepare the dendritic mesoporous SiO₂Microspheres (dSi);

s2: with tree-shaped mesoporous SiO₂The microspheres are used as affinity templates, and Fe (acac) is added₃Synthesizing arborescent mesoporous SiO by high-temperature pyrolysis method through (ferric triacetylacetonate) and PEI (polyethyleneimine)₂/Fe₃O₄A composite carrier;

s3: adding gold ions, chelating amino groups with the gold ions to obtain gold seeds, and adding a reducing agent into the gold seeds to obtain gold particles;

s4: coating a layer of mesoporous silica on the surface of the whole carrier through a surfactant templating way.

Further, the step S1 is specifically as follows:

s1.1: adding TEA (triethylamine) into water, heating, stirring and mixing;

s1.2: adding CTAB and NaSal into the TEA mixed solution for reaction;

s1.3: adding TEOS into the reaction solution, and keeping the reaction solution at 80 ℃ for 2-6 h;

s1.4: centrifuging the product and washing with ethanol;

s1.5: heating the obtained precipitate in a mixed solution of hydrochloric acid and methanol for reaction, and removing the residual organic template in the pore channel;

s1.6: washing the product with the organic template removed with ethanol to obtain the arborescent mesoporous SiO₂Microspheres (dSi).

Preferably, the S1.5 step is repeated 2-3 times.

Further, the step S2 is specifically as follows:

s2.1: making tree-shaped mesoporous SiO₂Centrifuging the ethanol solution of microspheres to obtain wet precipitate, and mixing the wet precipitate with Fe (acac)₃Adding PEI into TEG (triethylene glycol) and performing ultrasonic dispersion;

s2.2: heating the mixed solution subjected to ultrasonic dispersion under a vacuum condition to remove ethanol;

s2.3: heating and stirring the mixed solution without the ethanol in the nitrogen atmosphere to react;

s2.4: when the temperature of the solution is cooled to room temperature, adding acetone with the same volume, and separating by using a magnet to obtain a product;

s2.5: washing the product with ethanol to obtain the dendriform mesoporous SiO₂/Fe₃O₄(dSi/Fe₃O₄) And (3) a composite carrier.

Preferably, the temperature in S2.3 is raised to 210 ℃ in the nitrogen atmosphere, and the mixture is stirred to react for 2 hours; then the temperature is increased to 290 ℃, and the stirring reaction is continued for 1 h.

Further, the step S3 is specifically as follows:

s3.1: to HAuCl₄Adding K into the solution₂CO₃Solution of Au³⁺Reduction to Au⁺；

S3.2: under ice bath, tree-shaped mesoporous SiO₂/Fe₃O₄(dSi/Fe₃O₄) Adding Au into the aqueous solution⁺Carrying out reaction on the solution;

s3.3: under vigorous stirring, the newly prepared NaBH is rapidly added to the reacted liquid₄Solution, the solution turns red;

s3.4: removing free gold particles through magnetic separation to obtain the tree-shaped mesoporous SiO₂/Fe₃O₄Au seed (dSi/Fe)₃O₄/Au seed) into water;

s3.5: to HAuCl₄Adding K into the solution₂CO₃The solution reacts, and the solution becomes colorless;

s3.6: adding tree-shaped mesoporous SiO into the colorless solution₂/Fe₃O₄Au seed (dSi/Fe)₃O₄Au seed) solution, stirring and mixing;

s3.7: first, PVP (polyvinylpyrrolidone) is added to the mixed solution to be stirred and mixed, and then, the mixed solution is stirred and mixedSlowly adding hydroxylamine hydrochloride solution for reaction, and centrifugally washing a reaction product to obtain the dendriform mesoporous SiO₂/Fe₃O₄/Au(dSi/Fe₃O₄/Au)。

Further, the step S4 is specifically as follows:

s4.1: taking tree-shaped mesoporous SiO₂/Fe₃O₄/Au(dSi/Fe₃O₄Au) is dissolved in CTAB solution, NaOH and TEOS are added for reaction, and the reaction product is centrifugally washed to obtain the dendriform mesoporous SiO₂/Fe₃O₄/Au/mSi(dSi/Fe₃O₄/Au/mSi)。

The prepared central radial-diplopore nano composite material can be applied to the recoverable circular catalysis of p-nitrophenol.

The invention adopts Cetyl Trimethyl Ammonium Bromide (CTAB) and sodium salicylate (NaSal) as structure directing agents and adopts an anion-assisted method to prepare a central radial macroporous tree-shaped silicon (dSi) template. Then, by utilizing the natural affinity of silanol groups on the surfaces of pores of the dSi nanospheres and iron oxide particles and taking dSi as an affinity template, the dendritic silicon dioxide/ferroferric oxide composite carrier (dSi/Fe) is synthesized in one step through a high-temperature pyrolysis method₃O₄). Then obtaining gold seeds through chelation of amino and metal ions, continuously adding a reducing agent to obtain gold particles with the particle size of about 6-7nm, wherein the small-particle nano gold seeds and the gold particles with the particle size of 6-7nm can be efficiently subjected to dSi/Fe₃O₄Filling the pore channel; and finally, coating a layer of mesoporous silica on the surface of the whole carrier through a surfactant templating way to construct a superparamagnetic nano-gold catalyst with a double-pore structure so as to realize recoverable cyclic catalysis of 4-nitrophenol.

Compared with the prior art, the invention has the following beneficial effects:

1. the macroporous template is synthesized by double surfactants in one step, and the method is simple, convenient and easy to implement and convenient to repeat and popularize.

2. The size of the aperture can be controlled by adjusting the reaction time of the center radial tree-shaped silicon template.

3. The tree-shaped silicon template has natural iron affinity and does not need any surface modification.

4. The effective loading of the noble metal catalyst can be realized through the chelation of the amino and the metal ions.

5. The double-pore carrier is realized by coating the surface mesoporous silicon, so that the full contact of reaction media is kept, and the fusion of noble metal Au particles and the loss of catalytic activity are avoided.

Drawings

In FIG. 1, (a) is dSi/Fe₃O₄a/Au/mSi synthesis scheme; (b-f) TEM images of nanoparticles at different reaction stages; wherein (b) dSi, (c) dSi/IO (Fe)₃O₄)，(d)dSi/IO/Au-s，(e)dSi/IO/Au，(f)dSi/IO/Au/mSi.

Figure 2 is a SEM image of center radial macroporous silicon at different reaction times.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer and more complete, the technical solutions in the embodiments of the present invention will be described below in conjunction with the embodiments of the present invention, and it is obvious that the described embodiments are a part of the embodiments of the present invention, but not all embodiments, and all other embodiments obtained by a person of ordinary skill in the art without creative efforts based on the embodiments of the present invention belong to the protection scope of the present invention.

Example 1

1) Tree-shaped mesoporous SiO₂Synthesis of microspheres (dSi):

68mg of TEA was added to 25mL of water and magnetically stirred in a water bath at 80 ℃ for 30 min. Then, 380mg of CTAB and 168mg of NaSal were added, and the reaction was continued for 1 hour. Then, 4mL of TEOS was added to the reaction solution, and the reaction solution was kept at 80 ℃ for 2 hours. The product was centrifuged and washed several times with ethanol. The obtained precipitate is reacted in a mixed solution of hydrochloric acid/methanol at 60 ℃ for 6h to remove the residual organic template in the pore channels, and the extraction step is repeated for 2-3 times. The final product was dispersed in 50mL of ethanol after washing with ethanol.

2)dSi/Fe₃O₄The synthesis of (2):

taking 7.5mL of the dSi ethanol solution obtained by the preparation, and separatingHeart, wet precipitate obtained, wet precipitate and 360mg Fe (acac)₃And 40mg PEI (Mw 1800) were added together to 30mL TEG. And (4) uniformly dispersing the mixture by ultrasonic waves. The solution was warmed to 70 ℃ under vacuum and held for more than 15min to remove the ethanol. Filling nitrogen into the bottle, heating to 210 ℃, and magnetically stirring for 2 hours; the temperature was increased to 290 ℃ and stirring was continued for 1 h. Cooling the solution to room temperature, adding an equal volume of acetone, separating with a magnet, and separating dSi/Fe₃O₄The microspheres were washed three more times with ethanol and finally dispersed in 10mL of water.

3)dSi/Fe₃O₄Synthesis of Au:

0.4mL of HAuCl was taken₄(50mM) solution 4ml H was added₂To O, 0.2mL of K was added₂CO₃Solution (0.2mol/L), mixing Au³⁺Reduction to Au⁺After 10min of reaction, the reaction solution turned from yellow to colorless. 1mL of the above dSi/Fe₃O₄The solution was dissolved in 16mL of water and Au was added while ice bath⁺In the solution, the reaction was carried out for 10 min. Taking 80uL of freshly prepared NaBH₄The solution (2mg/mL) was diluted to 2mL with water, added rapidly to the reaction with vigorous stirring, and stirred for 10min, whereupon the solution turned red. Magnetically separating to remove free gold particles and obtaining dSi/Fe₃O₄the/Au seed was dispersed in 4mL of water.

0.2mL of HAuCl was taken₄(50mM) solution 13.2mLH was added₂To O, 0.15mL of K was added₂CO₃The solution (0.2mol/L) was stirred for 10min, the solution became colorless, then 2mL dSi/Fe was added₃O₄Au seed solution, stirring for 10 min. Adding 2mL PVP (0.05g in 1mL water), stirring for 10min, slowly adding 2mL hydroxylamine hydrochloride solution (17.3mg in 10mL water), reacting for 1h, centrifuging and washing for 3 times to obtain dSi/Fe₃O₄/Au。

4)dSi/Fe₃O₄Synthesis of Au/mSi:

taking the dSi/Fe prepared above₃O₄Au was dissolved in 60mL CTAB (3mM) solution, 0.6mL NaOH (0.1M), 60uL TEOS was added, reacted for 24h, and centrifuged and washed three times.

4-Nitrophenol catalysis experiment

Get 6mL freshly prepared NaBH₄The solution (0.1M) was added to 3mL of 4-NP (4-nitrophenol) solution (2mM) and 20uL dSi/Fe was added₃O₄The UV absorbance was measured by taking 0.5mL of/Au/mSi catalyst (5mg/mL) every 1.5 min. There was no change after about 15 min.

Example 2

1) Tree-shaped mesoporous SiO₂Synthesis of microspheres (dSi):

68mg of TEA was added to 25mL of water and magnetically stirred in a water bath at 80 ℃ for 30 min. Then, 380mg of CTAB and 168mg of NaSal were added, and the reaction was continued for 1 hour. Subsequently, 4ml of TEOS was added to the reaction solution, and the reaction solution was kept at 80 ℃ for 4 hours. The product was centrifuged and washed several times with ethanol. The obtained precipitate is reacted in a mixed solution of hydrochloric acid/methanol at 60 ℃ for 6h to remove the residual organic template in the pore channels, and the extraction step is repeated for 2-3 times. The final product was dispersed in 50mL of ethanol after washing with ethanol.

2)dSi/Fe₃O₄The synthesis of (2):

centrifuging 7.5mL of the prepared dSi ethanol solution to obtain wet precipitate, mixing the wet precipitate with 360mg of Fe (acac)₃And 40mg PEI (Mw 1800) were added together to 30mL TEG. And (4) uniformly dispersing the mixture by ultrasonic waves. The solution was warmed to 70 ℃ under vacuum and held for more than 15min to remove the ethanol. Filling nitrogen into the bottle, heating to 210 ℃, and magnetically stirring for 2 hours; the temperature was increased to 290 ℃ and stirring was continued for 1 h. Cooling the solution to room temperature, adding an equal volume of acetone, separating with a magnet, and separating dSi/Fe₃O₄The microspheres were washed three more times with ethanol and finally dispersed in 10mL of water.

3)dSi/Fe₃O₄Synthesis of Au:

0.4mL of HAuCl was taken₄(50mM) solution 4ml H was added₂To O, 0.2mL of K was added₂CO₃Solution (0.2mol/L), mixing Au³⁺Reduction to Au⁺After 10min of reaction, the reaction solution turned from yellow to colorless. 1mL of the above dSi/Fe₃O₄The solution was dissolved in 16mL of water and Au was added while ice bath⁺In the solution, the reaction was carried out for 10 min. Taking 80uL of freshly prepared NaBH₄The solution (2mg/mL) was diluted to 2mL with water and added rapidly to the reaction with vigorous stirringThen, the mixture was stirred for 10min, and the solution became red. Magnetically separating to remove free gold particles and obtaining dSi/Fe₃O₄the/Austed was dispersed in 4mL of water.

0.2mL of HAuCl was taken₄(50mM) solution 13.2mL H was added₂To O, 0.15mL of K was added₂CO₃The solution (0.2mol/L) was stirred for 10min, the solution became colorless, then 2mL dSi/Fe was added₃O₄Au seed solution, stirring for 10 min. Adding 2mL PVP (0.05g in 1mL water), stirring for 10min, slowly adding 2mL hydroxylamine hydrochloride solution (17.3mg in 10mL water), reacting for 1h, centrifuging and washing for 3 times to obtain dSi/Fe₃O₄/Au。

4)dSi/Fe₃O₄Synthesis of Au/mSi:

taking the dSi/Fe prepared above₃O₄Au was dissolved in 60mL CTAB (3mM) solution, 0.6mL NaOH (0.1M), 60uL TEOS was added, reacted for 24h, and centrifuged and washed three times.

4-Nitrophenol catalysis experiment

6mL of freshly prepared NaBH was taken₄The solution (0.1M) was added to 3mL of 4-NP solution (2mM) and 20uL dSi/Fe was added₃O₄The UV absorbance was measured by taking 0.5mL of/Au/mSi catalyst (5mg/mL) every 1.5 min. There was no change after about 15 min.

Example 3

1) Tree-shaped mesoporous SiO₂Synthesis of microspheres (dSi):

68mg of TEA was added to 25mL of water and magnetically stirred in a water bath at 80 ℃ for 30 min. Then, 380mg of CTAB and 168mg of NaSal were added, and the reaction was continued for 1 hour. Then, 4mL of TEOS was added to the reaction solution, and the reaction solution was kept at 80 ℃ for 6 hours. The product was centrifuged and washed several times with ethanol. The obtained precipitate is reacted in a mixed solution of hydrochloric acid/methanol at 60 ℃ for 6h to remove the residual organic template in the pore channels, and the extraction step is repeated for 2-3 times. The final product was dispersed in 50mL of ethanol after washing with ethanol.

2)dSi/Fe₃O₄The synthesis of (2):

centrifuging 7.5mL of the prepared dSi ethanol solution to obtain wet precipitate, mixing the wet precipitate with 360mg of Fe (acac)₃And 40mg PEI (Mw &)1800) Added together to 30mL of TEG. And (4) uniformly dispersing the mixture by ultrasonic waves. The solution was warmed to 70 ℃ under vacuum and held for more than 15min to remove the ethanol. Filling nitrogen into the bottle, heating to 210 ℃, and magnetically stirring for 2 hours; the temperature was increased to 290 ℃ and stirring was continued for 1 h. Cooling the solution to room temperature, adding an equal volume of acetone, separating with a magnet, and separating dSi/Fe₃O₄The microspheres were washed three more times with ethanol and finally dispersed in 10mL of water.

3)dSi/Fe₃O₄Synthesis of Au:

0.4mL of HAuCl was taken₄(50mM) solution 4ml H was added₂To O, 0.2mL of K was added₂CO₃Solution (0.2mol/L), mixing Au³⁺Reduction to Au⁺After 10min of reaction, the reaction solution turned from yellow to colorless. 1mL of the above dSi/Fe₃O₄The solution was dissolved in 16mL of water and Au was added while ice bath⁺In the solution, the reaction was carried out for 10 min. Taking 80uL of freshly prepared NaBH₄The solution (2mg/mL) was diluted to 2mL with water, added rapidly to the reaction with vigorous stirring, and stirred for 10min, whereupon the solution turned red. Magnetically separating to remove free gold particles and obtaining dSi/Fe₃O₄the/Au seed was dispersed in 4mL of water.

0.2mL of HAuCl was taken₄(50mM) solution 13.2mL H was added₂To O, 0.15mL of K was added₂CO₃The solution (0.2mol/L) was stirred for 10min, the solution became colorless, then 2mL dSi/Fe was added₃O₄Au seed solution, stirring for 10 min. Adding 2mL PVP (0.05g in 1mL water), stirring for 10min, slowly adding 2mL hydroxylamine hydrochloride solution (17.3mg in 10mL water), reacting for 1h, centrifuging and washing for 3 times to obtain dSi/Fe₃O₄/Au。

4)dSi/Fe₃O₄Synthesis of Au/mSi:

taking the dSi/Fe prepared above₃O₄Au was dissolved in 60mL CTAB (3mM) solution, 0.6mL NaOH (0.1M), 60uL TEOS was added, reacted for 24h, and centrifuged and washed three times.

4-Nitrophenol catalysis experiment

6mL of freshly prepared NaBH was taken₄The solution (0.1M) was added to 3mL of 4-NP solution (2mM),adding 20uL dSi/Fe₃O₄The UV absorbance was measured by taking 0.5mL of/Au/mSi catalyst (5mg/mL) every 1.5 min. There was no change after about 15 min.

Product characterization

Examples 1-3 arborescent mesoporous SiO₂In the synthesis step of the microsphere (dSi), the reaction time after TEOS is added is 2h, 4h and 6h respectively, and the aperture of the corresponding central radial silicon dioxide is 30nm, 20nm and 10 nm.

Referring specifically to FIG. 2, wherein (a) corresponds to example 1, the reaction time is 2h, and the pore diameter is 30 nm; (b) the reaction time is 4h corresponding to example 2, and the pore diameter is 20 nm; (c) corresponding to example 3, reaction time was 6h and pore diameter was 10 nm.

The above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.