CN114044507A - Honeycomb ordered mesoporous microsphere and preparation method thereof - Google Patents

Honeycomb ordered mesoporous microsphere and preparation method thereof Download PDF

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CN114044507A
CN114044507A CN202111439249.9A CN202111439249A CN114044507A CN 114044507 A CN114044507 A CN 114044507A CN 202111439249 A CN202111439249 A CN 202111439249A CN 114044507 A CN114044507 A CN 114044507A
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inorganic oxide
microspheres
microsphere
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CN114044507B (en
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朱锦涛
王勉
邓仁华
邓比特
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Huazhong University of Science and Technology
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Abstract

The invention discloses a honeycomb ordered mesoporous microsphere and a preparation method thereof. The microspheres are in a flat cake shape and comprise a framework and a plurality of vertically through columnar through holes, wherein the framework is a carbon material loaded with metal nanoparticles, a composite material of inorganic oxide and carbon or inorganic oxide; the carbon is doped with nitrogen, bromine or iodine elements. The preparation method comprises the following steps: preparing flat microspheres by adopting a block copolymer three-dimensional soft-limit assembly method, soaking the flat microspheres in a solution containing a metal nanoparticle precursor or a solution containing an inorganic oxide precursor, and calcining the metal nanoparticle/polymer composite microspheres or the inorganic oxide/polymer composite microspheres. The microsphere has larger and uniform pore diameter, the pore passage is a vertically through cylindrical pore passage, the material transmission efficiency is high, the transmission rate consistency is good, the thickness of the framework is thick, and the problem of structural collapse of the traditional mesoporous microsphere caused by thinner pore wall is solved.

Description

Honeycomb ordered mesoporous microsphere and preparation method thereof
Technical Field
The invention belongs to the technical field of mesoporous materials, and particularly relates to a honeycomb-shaped ordered mesoporous microsphere and a preparation method thereof.
Background
The mesoporous material is a porous material with the aperture of 2-50 nm. In 1992, a Kresge team firstly utilizes a template method to prepare a honeycomb mesoporous molecular sieve MCM-41 with an ordered structure. The achievement causes huge booming in the chemical and material science communities and raises the research hot trend of numerous scholars at home and abroad on the mesoporous materials. The Gallen d. stucky team and the Shinae Jun team subsequently distributed the soft template method and the hard template method, respectively, in 1998 and 1999. The mesoporous material has extremely high specific surface area due to the special physical and chemical properties and mesoporous structure, and can obviously improve the utilization rate of raw materials by loading functional substances. From molecular sieve to mesoporous silicon and then to mesoporous carbon, mesoporous inorganic oxide, mesoporous metal and the like, mesoporous nanomaterials are applied to various fields such as fuel cells, biomedicines and the like, and show wide application prospects.
The ordered mesoporous material has larger specific surface area, relatively larger aperture and regular pore channel structure, can process larger molecules or groups, and is a good shape-selective catalyst. In particular, the ordered mesoporous materials exhibit catalytic activity superior to zeolite molecular sieves in catalyzing reactions involving large numbers of molecules. The aperture of the ordered mesoporous material can be continuously adjusted within the range of 2-50nm and has no physiological toxicity, so that the ordered mesoporous material is very suitable for fixing and separating enzyme, protein and the like. Many of the existing mesoporous microspheres are spherical holes, have small aperture, and have very limited effect if the inner pore channels are not communicated without special treatment. The honeycomb structure is a highly ordered and stable pore structure. The flat particles with honeycomb column-shaped mesoporous channels are an ideal mesoporous molecular sieve. Although cylindrical channels can be obtained by a large number of methods, the channels are curved and have poor structural order, and thus, the mesoporous molecular sieve is difficult to be used as an ideal mesoporous molecular sieve. The order of the pore structure plays a decisive role in the uniformity of material transmission and is a key index for determining the performance of the material. Therefore, the development of the ordered mesoporous molecular sieve has very important research significance and practical value.
Besides, mesoporous materials are also widely used in the field of fuel cells. Fuel cell catalysts are typically dispersed on carbon-based supports, especially metal carbon-based catalysts (Pt, Co, Pd, Au, Ag, Cu, Ni). The carbon-based catalyst carrier comprises carbon black, graphene, carbon nanotubes and the like, and the carbon-based catalyst carrier can improve the conductivity of the catalyst and increase the specific surface area of the catalyst. However, the current array of commercial carbon-based catalysts, including carbon black, still has some drawbacks. For example, for commercial Pt/C catalysts, Pt nanoparticles are detached from the carbon support and tend to agglomerate into larger sized particles, and Pt is covered so that its catalytically active sites are not sufficiently exposed, the utilization rate is reduced, and the catalytic performance is degraded.
The mesoporous carbon-based carrier is an effective method for improving the electrocatalysis performance. In recent years, the structural design of catalyst pore channels has been one of the research hotspots at home and abroad. The abundant pore structure can increase the specific surface area of the catalyst, fully expose the active sites of the metal nanoparticles and improve the utilization rate of the material. The mass transport rate of conventional spherical porous materials is limited. The realization of the homogenization, enrichment and ordering of the pore structure is a problem and a challenge of the existing porous carbon-based catalyst and is a key factor influencing the performance of the material. On the other hand, the thickness of the mesoporous material wall plays an important role in the overall stability of the material, and the traditional mesoporous material wall prepared by taking the amphiphilic surfactant as a template is very thin and low in structural strength. Therefore, the development of the preparation method of the mesoporous carbon spheres capable of efficiently loading the metal nanoparticles, uniform pores, large pore diameters, orderliness and thick walls has very important research value and significance. The composite mesoporous carbon spheres can be used as a fuel cell catalyst, and can be used as lithium battery electrodes and CO2The capture and super capacitor have important application value.
Disclosure of Invention
The invention provides a honeycomb ordered mesoporous microsphere and a preparation method thereof, aiming at providing a preparation method of a metal nanoparticle/carbon, inorganic oxide or inorganic oxide/carbon composite mesoporous microsphere with a through vertical pore passage, an ordered structure, a large pore diameter and a thick wall, so as to solve the technical problems that the traditional mesoporous material wall prepared by taking an amphiphilic surfactant as a template is very thin and has low structural strength.
In order to achieve the above object, according to one aspect of the present invention, there is provided a honeycomb ordered mesoporous microsphere, the microsphere is in a flat cake shape, and comprises a skeleton and a plurality of vertical through columnar through holes, wherein the skeleton is a carbon material loaded with metal nanoparticles, a composite material of an inorganic oxide and carbon, or an inorganic oxide; the carbon is doped with nitrogen, bromine or iodine elements. Wherein the nitrogen element comes from a pyridine group in the diblock copolymer, and the bromine and iodine elements come from a stabilizing agent.
Preferably, the size of the microspheres is 0.05-10 μm, the apertures of the plurality of columnar through holes are the same, and the aperture of each columnar through hole is 2-50 nm; the thickness of the microsphere skeleton is 5-50 nm; the hole period (namely the hole center distance between two adjacent holes) of the columnar through holes is 1-100 nm, and preferably, the size of the microsphere is 0.1-1 mu m; preferably, the period of the columnar through holes is 10-50 nm. The size of the microsphere refers to the size of the whole microsphere, namely the size of the long axis of the oblate ellipsoid.
Preferably, the metal nanoparticles are at least one of gold, silver, copper, palladium, platinum, cobalt and nickel, and the particle size of the metal nanoparticles is 1-30 nm; the loading amount of the metal nano particles is 10-50%.
Preferably, the inorganic oxide is one of silicon dioxide, titanium dioxide, tin dioxide, zinc oxide and aluminum oxide; the mass ratio of the inorganic oxide in the composite material of the inorganic oxide and the carbon is 10-100%.
According to another aspect of the present invention, there is provided a method for preparing honeycomb-shaped ordered mesoporous microspheres, comprising the steps of:
(1) preparing flat microspheres with hexagonal-stacking cylindrical structures inside by using a three-dimensional soft-limited block copolymer assembly method by using a two-block copolymer as a raw material, wherein the two-block copolymer comprises a polymer for forming a columnar phase and a polymer for forming a continuous phase;
(2) dipping the flat microspheres into a solution containing a metal nanoparticle precursor to enable the continuous phase to adsorb the metal nanoparticle precursor, and adding a reducing agent to obtain metal nanoparticle/polymer composite microspheres;
or, dipping the flat microspheres in a solution containing an inorganic oxide precursor to enable the continuous phase to adsorb the inorganic oxide precursor, and hydrolyzing to obtain inorganic oxide/polymer composite microspheres;
(3) calcining the metal nano particle/polymer composite microsphere or the inorganic oxide/polymer composite microsphere to decompose the columnar phase to form a columnar through hole, and carbonizing a continuous phase in the metal nano particle/polymer composite microsphere to form a framework; or the continuous phase in the inorganic oxide/polymer composite microsphere is decomposed into inorganic oxide to form a framework; or the continuous phase in the inorganic oxide/polymer composite microsphere is carbonized to form a skeleton; thereby obtaining the mesoporous microsphere.
Preferably, the step (1) specifically comprises:
(101) fully dissolving the two-block copolymer in an organic solvent immiscible with water, and sequentially adding an alkylphenol structure regulator and a stabilizer to obtain a mixed solution; preferably, the organic solvent is halogenated alkane, the stabilizer is alkane of which both ends are respectively substituted by one halogen element, and the alkylphenol structure regulator is m-pentadecylphenol; the concentration of the two-block copolymer in an organic solvent is 0.5-30.0 mg/mL, and the concentration of the alkylphenol structure regulator is 0.5-30.0 mg/mL; preferably, the stabilizer is 1, 4-dibromobutane or 1, 5-dibromopentane; preferably, the organic solvent is chloroform or dichloromethane;
(102) and mixing the mixed solution with an aqueous solution containing a surfactant, emulsifying, and volatilizing an organic solvent in the emulsion to obtain the flat microspheres, wherein the surfactant is preferably PVA, and the concentration of the surfactant is 1.0-10.0 mg/mL.
Wherein, it should be noted that the stabilizer is used for enhancing the crosslinking degree of the continuous phase, thereby enhancing the stability of the continuous phase skeleton, so that the skeleton structure of the microspheres will not collapse after calcination. The resulting flat configuration is a unique advantage of the limited assembly of the present invention. The key point is that: based on the three-dimensional, soft-constrained assembly of the diblock copolymer with the alkylphenol type structure modifier, a phase-separated structure with a columnar phase can be produced. Such microspheres having a columnar phase structure are more likely to form a flat shape due to interfacial interaction, and the flat microspheres have a lower curvature relative to spherical microspheres, which can contribute to the formation of a stable structure.
Preferably, the polymer constituting the columnar phase is polybutadiene, polyisoprene, polyacrylate or polystyrene, and the polymer constituting the continuous phase is polyvinylpyridine; the molecular weight of a polymer forming a columnar phase in the two-block copolymer is 5000-100000, and the molecular weight of a polymer forming a continuous phase in the two-block copolymer is 5000-100000; the ratio of the molecular weight of the polymer forming the columnar phase to the molecular weight of the polymer forming the continuous phase in the two-block copolymer is 0.8-1.2. Preferably, the diblock copolymer is polystyrene-poly-4-vinylpyridine.
For example, the diblock copolymer may be: PS (polystyrene) with high sensitivity9.8k-b-P4VP10k、PS20k-b-P4VP17k、PS22k-b-P4VP21.6kAnd the like.
Preferably, the alkylphenol structure regulator is added in an amount satisfying: the molar weight ratio of the diblock copolymer to the alkylphenol structure regulator is 1 (0.6-0.8) based on the molar weight of the pyridine group of the polymer forming the continuous phase, and the addition amount of the stabilizer satisfies the following requirements: the molar ratio of the organic solvent to which the alkylphenol-based structure-modifying agent has been added to the stabilizer is 1 (0.4 to 1.0) in terms of the molar amount of the pyridine group of the polymer constituting the continuous phase.
Wherein, the alkylphenol structure regulator and the polymer form hydrogen bonds, and the phase separation structure of the block copolymer is effectively regulated and controlled. By changing the content of the alkylphenol structure regulator, the microspheres with different phase structures can be obtained under the condition of three-dimensional soft limitation. When the content of the alkylphenol type structure regulator is too low, onion-shaped microspheres are formed. When the content of the alkylphenol type structure-regulating agent is more than 0.8, although the columnar phase microsphere is also formed, the purification is difficult.
Preferably, the calcination treatment is specifically: calcining the metal nano particle/polymer composite microsphere for 2-4 hours at the temperature of 400-550 ℃ in a nitrogen atmosphere; or calcining the inorganic oxide/polymer composite microspheres for 2-4 hours at 400-550 ℃ in a nitrogen atmosphere, and then calcining for 2-4 hours at 300-700 ℃ in an air atmosphere; or calcining the inorganic oxide/polymer composite microspheres for 2-4 hours at 400-550 ℃ in a nitrogen atmosphere.
Preferably, the metal nanoparticle precursor is one of potassium tetrachloroplatinate, potassium tetrachloropalladate, tetrachloroauric acid, silver nitrate, cobalt chloride and copper chloride; the inorganic oxide precursor is one of tetraethoxysilane, tetraisobutyl titanate, stannic chloride, zinc acetate and aluminum nitrate; the reducing agent is ascorbic acid or sodium borohydride.
Preferably, in the step (102), the mixed solution is mixed with an aqueous solution containing a surfactant and then emulsified, and then the organic solvent in the emulsion is volatilized to obtain the flat microspheres, specifically: and mixing the mixed solution with an aqueous solution containing a surfactant, uniformly crossing the membrane for several times through a hand-push type micro-membrane extrusion emulsifying device with uniform membrane aperture to obtain an oil/water emulsion, and volatilizing the oil/water emulsion for 48 hours in an open way to completely volatilize the organic solvent. The pore diameter of the filter membrane in the hand-push type micro-membrane extrusion emulsification device can be 0.45 μm, 0.20 μm or 1.0 μm. The membrane passing times are 5-40 times when a hand-push type miniature membrane extrusion emulsifying device is used.
In general, at least the following advantages can be obtained by the above technical solution contemplated by the present invention compared to the prior art.
(1) The mesoporous microsphere provided by the invention has a honeycomb ordered mesoporous structure, the pore diameter is larger and uniform, the pore channel is a vertically through cylindrical pore channel, the material transmission efficiency is high, and the transmission rate consistency is good. The thickness (wall thickness) of the framework is thicker than that of other materials, so that the problem of structural collapse of the traditional mesoporous microsphere due to thinner pore walls is solved. The preparation method provided by the invention is different from the prior method for co-assembling the polymer and the precursor, the polymerization template is prepared firstly, the template has good stability, good structural consistency and wide adjustable range of aperture size. In the traditional solvent volatilization induced co-assembly strategy, the precursor needs to participate in the assembly process. And the process of assembling the polymer and the precursor is difficult to control due to the fact that hydrolysis of some metal salt precursors is too violent.
Specifically, the method comprises the steps of firstly adopting three-dimensional soft limited assembly of the block copolymer to obtain a polymer microsphere template, then adsorbing a precursor, and then calcining. The three-dimensional soft-limited assembly of the block copolymer can obtain the flat polymer microspheres with columnar phases. The polymer microsphere with ordered and anisotropic structure can be used as a template of a mesoporous microsphere. The assembly process is separated from the process of adsorbing the precursor so that the formation of the template is not affected by the precursor reduction or hydrolysis conditions. The prepared template can be suitable for adsorbing most precursors, including precursors of metal and inorganic oxide, and has mild reaction conditions. The method has good controllability and universality.
(2) The preferred use of the diblock copolymer polystyrene-poly-4-vinylpyridine in the present invention has unique advantages over other materials. Polystyrene is not easy to combine with metal nano particles or inorganic oxide precursors, and the carbon residue rate after calcination is extremely low. The polyvinyl pyridine can be combined with metal nano particles or inorganic oxide precursors, can be crosslinked, and has higher carbon residue rate after crosslinking. This provides a foundation for the formation of mesoporous microspheres, the improvement of the carbon residue rate and the improvement of the stability of the structure.
(3) The mesoporous microsphere carbon matrix loaded with the metal nanoparticles has nitrogen, bromine and other impurity elements. The mixed elements in the carbon matrix can enhance the conductivity of the carbon material and improve the electrochemical performance of the carbon material.
(4) The polyvinyl pyridine is preferably used in the invention to adsorb the polymer of the precursor, and the applicable metal nano particles and inorganic oxides are wide in range. Suitable metal nanoparticles include gold, silver, platinum, palladium, copper, cobalt, nickel, and the like. Suitable inorganic oxides include silicon dioxide, titanium dioxide, tin dioxide, zinc oxide, aluminum oxide, and the like.
(5) The mesoporous microsphere provided by the invention can be applied to fuel cell catalysts, lithium battery electrodes and CO2Capture, super capacitor, biological medicine, separation, sensing and other fields.
Drawings
Fig. 1 (a) is a high-magnification scanning electron microscope image of the platinum/carbon mesoporous microsphere prepared in example 1 of the present invention, fig. 1 (b) is a high-magnification transmission electron microscope image of the platinum/carbon mesoporous microsphere prepared in example 1 of the present invention, and fig. 1 (c) is a lattice image of platinum in the high-magnification transmission electron microscope of the platinum/carbon mesoporous microsphere prepared in example 1 of the present invention;
FIG. 2 is a transmission electron microscope image of characteristics of the mesoporous Pt/C microspheres prepared in example 2 of the present invention;
fig. 3 is a transmission electron microscope image of the carbon/silica mesoporous microsphere prepared in example 4 of the present invention at (a), and fig. 3 is a scanning electron microscope image of the carbon/silica mesoporous microsphere prepared in example 4 of the present invention at (b).
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
Example 1
(1) PS with 10.0mg/mL9.8k-b-P4VP10kThe solution and 10.0mg/mL PDP solution, oil-soluble organic solvent is chloroform. A5.0 mg/mL aqueous PVA solution was prepared. Based on the molar amount of pyridine groups in the PS-b-P4VP solution, adding PS9.8k-b-P4VP10kSolutions, PDP solutions were as follows 1: 0.6(4 VP: PDP) was added thereto, and the mixture was stirred at room temperature for 12 hours while controlling the total volume of the mixture to 500. mu.L. With PS9.8k-b-P4VP10kMixing the mixed solution with 1, 4-Dibromopentane (DBP) according to the molar weight of pyridine groups in the solution as follows: 0.4(4 VP: DBP) and stirred for 4 hours.
(2) After 100 mul of the mixed solution is mixed with 1mL of PVA solution, the mixture is filtered for 20 times by a manual membrane filtering device and is placed in an environment at 30 ℃ for 48 hours of open volatilization. Taking the volatilized solution for centrifugation at 1400 rpm for 10 min, and removing the supernatant.
(3) The precipitate was dispersed in a mixture of 500. mu.L of water and 500. mu.L of ethanol. By using PS in the mixed solution9.8k-b-P4VP10kMixing the solution with potassium tetrachloroplatinate (K) based on the molar weight of pyridine group2PtCl4) According to the following steps of 1: 0.5(4 VP: Pt) and stirred for 12 hours. Based on the molar amount of potassium tetrachloroplatinate in the solution, mixing the solution and ascorbic acid according to the weight ratio of 1: 3 and stirring for 12 hours. And (3) centrifuging and concentrating the solution at the rotating speed of 1400 rpm for 10 minutes.
(4) And (3) drying the precipitate, placing the dried precipitate in a tubular furnace, calcining for 2 hours at 450 ℃ under the protection of nitrogen, and obtaining the platinum-loaded mesoporous carbon spheres with a platinum loading of 50 mol%, uniform pores and a honeycomb cylindrical pore channel structure, wherein the pore period is 18.4nm, the pore diameter is 9.9nm, and the wall thickness is 6.8nm as shown in (a) to (c) of the figure 1.
Example 2
(1) PS with 10.0mg/mL9.8k-b-P4VP10kThe solution and 10.0mg/mL PDP solution, the organic solvent is chloroform. A5.0 mg/mL aqueous PVA solution was prepared. Based on the molar amount of pyridine groups in the PS-b-P4VP solution, adding PS9.8k-b-P4VP10kSolutions, PDP solutions were as follows 1: 0.6(4 VP: PDP) was added thereto, and the mixture was stirred at room temperature for 12 hours while controlling the total volume of the mixture to 500. mu.L. With PS9.8k-b-P4VP10kTaking the molar weight of pyridine groups in the solution as a reference, mixing the mixed solution with 1, 4-dibromopentane according to the weight ratio of 1: 0.4(4 VP: DBP) and stirred for 4 hours.
(2) After 100 mul of the mixed solution is mixed with 1mL of PVA solution, the mixture is filtered for 10 times by a manual membrane filtering device and is placed in an environment at 30 ℃ for 48 hours of open volatilization. Taking the volatilized solution for centrifugation at 1400 rpm for 10 min, and removing the supernatant.
(3) The precipitate was dispersed in a mixture of 500. mu.L of water and 500. mu.L of ethanol. By using PS in the mixed solution9.8k-b-P4VP10kMixing the solution with potassium tetrachloroplatinate (K) based on the molar weight of pyridine group2PtCl4) According to the following steps of 1: mixed at a ratio of 0.2 and stirred for 12 hours. Based on the molar amount of potassium tetrachloroplatinate in the solution, mixing the solution and ascorbic acid according to the weight ratio of 1: 3 and stirring for 12 hours. And (3) centrifuging and concentrating the solution at the rotating speed of 1400 rpm for 10 minutes.
(4) And (3) drying the precipitate, placing the dried precipitate in a tubular furnace, calcining for 4 hours at 500 ℃ under the protection of nitrogen, and obtaining the platinum-loaded mesoporous carbon spheres with the platinum loading of 20 mol%, uniform pores and honeycomb cylindrical pore channel structures, wherein the pore period is 18.0nm, the pore diameter is 7.3nm, and the wall thickness is 9.3nm, as shown in figure 2.
Example 3
(1) PS with 10.0mg/mL9.8k-b-P4VP10kThe solution and 10.0mg/mL PDP solution, the organic solvent was methylene chloride. A5.0 mg/mL aqueous PVA solution was prepared. Based on the molar amount of pyridine groups in the PS-b-P4VP solution, adding PS9.8k-b-P4VP10kSolutions, PDP solutions were as follows 1: 0.6(4 VP: PDP) was added thereto, and the mixture was stirred at room temperature for 12 hours while controlling the total volume of the mixture to 500. mu.L. With PS9.8k-b-P4VP10kTaking the molar weight of pyridine groups in the solution as a reference, mixing the mixed solution with 1, 4-dibromobutane according to the weight ratio of 1: 0.4(4 VP: DBP) and stirred for 4 hours.
(2) After 100 mul of the mixed solution is mixed with 1mL of PVA solution, the mixture is filtered for 10 times by a manual membrane filtering device and is placed in an environment at 30 ℃ for 48 hours of open volatilization. Taking the volatilized solution for centrifugation at 1400 rpm for 10 min, and removing the supernatant.
(3) The precipitate was dispersed in a mixture of 500. mu.L of water and 500. mu.L of ethanol. By using PS in the mixed solution9.8k-b-P4VP10kMixing the solution with potassium tetrachloroplatinate (K) based on the molar weight of pyridine group2PtCl4) According to the following steps of 1: mixed at a ratio of 0.25 and stirred for 12 hours. Based on the molar amount of potassium tetrachloroplatinate in the solution, mixing the solution and ascorbic acid according to the weight ratio of 1: 3 and stirring for 12 hours. Centrifuging and concentrating the above solution at 1400 deg.CRpm, centrifugation time 10 minutes.
(4) And drying the precipitate, placing the dried precipitate in a tubular furnace, and calcining the dried precipitate for 4 hours at 500 ℃ under the protection of nitrogen to obtain the platinum-loaded mesoporous carbon spheres with the platinum loading of 25 mol%, uniform pores and honeycomb cylindrical pore channel structures.
Example 4
(1) PS with 10.0mg/mL20k-b-P4VP17kThe solution and 10.0mg/mL PDP solution, the organic solvent was methylene chloride. A5.0 mg/mL aqueous PVA solution was prepared. With PS20k-b-P4VP17kBased on the molar amount of pyridine groups in the solution, PS is added20k-b-P4VP17kThe solution and the PDP solution are mixed according to a molar ratio of 1: 0.6(4 VP: PDP) and stirred at room temperature for 12 hours. With PS20k-b-P4VP17kMixing the mixed solution with 1, 4-Dibromopentane (DBP) according to the molar weight of pyridine groups in the solution as follows: 0.4(4 VP: DBP) and stirred for 4 hours.
(2) After 100 mu L of the mixed solution is mixed with 1mL of PVA solution, the mixture is subjected to membrane filtration for 10 times by adopting a manual membrane filtration device and is placed in an environment at 30 ℃ for 48 hours of open volatilization. Taking the volatilized solution for centrifugation at 1400 rpm for 10 min, and removing the supernatant.
(3) The precipitate was dispersed in a mixture of 1mL of water and 1mL of ethanol. To the above solution was added 3. mu.L of ethyl orthosilicate and stirred for 12 hours. To the solution was added a mixture of 40. mu.L of aqueous ammonia and 1mL of ethanol. And (3) centrifuging and concentrating the solution at the rotating speed of 1400 rpm for 10 minutes.
(4) And (3) drying the precipitate, placing the dried precipitate in a tube furnace, calcining for 4 hours at 450 ℃ under the protection of nitrogen, and obtaining the carbon/silicon dioxide mesoporous microsphere, wherein the carbon/silicon dioxide mesoporous microsphere is shown in (a) - (b) in figure 3, the pore period is 31.7nm, the pore diameter is 11.7nm, and the wall thickness is 15.7 nm.
It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims (10)

1. The honeycomb ordered mesoporous microsphere is characterized by being in a flat cake shape and comprising a framework and a plurality of vertically through columnar through holes, wherein the framework is a carbon material loaded with metal nanoparticles, a composite material of an inorganic oxide and carbon or an inorganic oxide; the carbon is doped with nitrogen, bromine or iodine elements.
2. The mesoporous microsphere of claim 1, wherein the microsphere has a size of 0.05-10 μm, the plurality of columnar through holes have the same pore diameter, and the pore diameter of the columnar through holes is 2-50 nm; the thickness of the microsphere skeleton is 5-50 nm; the period of the columnar through holes is 1-100 nm, and preferably, the size of the microspheres is 0.1-1 mu m; preferably, the period of the columnar through holes is 10-50 nm.
3. The mesoporous microsphere of claim 1 or 2, wherein the metal nanoparticles are at least one of gold, silver, copper, palladium, platinum, cobalt and nickel, and the particle size of the metal nanoparticles is 1-30 nm; the loading amount of the metal nano particles is 10-50%.
4. The mesoporous microsphere of claim 1 or 2, wherein the inorganic oxide is one of silica, titanium dioxide, tin dioxide, zinc oxide, and alumina; the mass ratio of the inorganic oxide in the composite material of the inorganic oxide and the carbon is 10-100%.
5. A method for preparing the honeycomb-shaped ordered mesoporous microspheres according to any one of claims 1 to 4, comprising the following steps:
(1) preparing flat microspheres with hexagonal-stacking cylindrical structures inside by using a three-dimensional soft-limited block copolymer assembly method by using a two-block copolymer as a raw material, wherein the two-block copolymer comprises a polymer for forming a columnar phase and a polymer for forming a continuous phase;
(2) dipping the flat microspheres into a solution containing a metal nanoparticle precursor to enable the continuous phase to adsorb the metal nanoparticle precursor, and adding a reducing agent to obtain metal nanoparticle/polymer composite microspheres;
or, dipping the flat microspheres in a solution containing an inorganic oxide precursor to enable the continuous phase to adsorb the inorganic oxide precursor, and hydrolyzing to obtain inorganic oxide/polymer composite microspheres;
(3) calcining the metal nano particle/polymer composite microsphere or the inorganic oxide/polymer composite microsphere to decompose the columnar phase to form a columnar through hole, and carbonizing a continuous phase in the metal nano particle/polymer composite microsphere to form a framework; or the continuous phase in the inorganic oxide/polymer composite microsphere is decomposed into inorganic oxide to form a framework; or the continuous phase in the inorganic oxide/polymer composite microsphere is carbonized to form a skeleton; thereby obtaining the mesoporous microsphere.
6. The preparation method according to claim 5, wherein the step (1) specifically comprises:
(101) fully dissolving the two-block copolymer in an organic solvent immiscible with water, and sequentially adding an alkylphenol structure regulator and a stabilizer to obtain a mixed solution; preferably, the organic solvent is halogenated alkane, the stabilizer is alkane of which both ends are respectively substituted by one halogen element, and the alkylphenol structure regulator is m-pentadecylphenol; the concentration of the two-block copolymer in an organic solvent is 0.5-30.0 mg/mL, and the concentration of the alkylphenol structure regulator is 0.5-30.0 mg/mL; preferably, the stabilizer is 1, 4-dibromobutane or 1, 5-dibromopentane; preferably, the organic solvent is chloroform or dichloromethane;
(102) and mixing the mixed solution with an aqueous solution containing a surfactant, emulsifying, and volatilizing an organic solvent in the emulsion to obtain the flat microspheres, wherein the surfactant is preferably PVA, and the concentration of the surfactant is 1.0-10.0 mg/mL.
7. The method according to claim 5, wherein the polymer constituting the columnar phase is polybutadiene, polyisoprene, polyacrylate or polystyrene, and the polymer constituting the continuous phase is polyvinylpyridine; the molecular weight of a polymer forming a columnar phase in the two-block copolymer is 5000-100000, and the molecular weight of a polymer forming a continuous phase in the two-block copolymer is 5000-100000; the ratio of the molecular weight of the polymer forming the columnar phase in the two-block copolymer to the molecular weight of the polymer forming the continuous phase is 0.8-1.2; preferably, the diblock copolymer is polystyrene-poly-4-vinylpyridine.
8. The method of claim 7, wherein the alkylphenol structure-regulating agent is added in an amount satisfying: the molar weight ratio of the diblock copolymer to the alkylphenol structure regulator is 1 (0.6-0.8) based on the molar weight of the pyridine group of the polymer forming the continuous phase, and the addition amount of the stabilizer satisfies the following requirements: the molar ratio of the organic solvent to which the alkylphenol-based structure-modifying agent has been added to the stabilizer is 1 (0.4 to 1.0) in terms of the molar amount of the pyridine group of the polymer constituting the continuous phase.
9. The method according to claim 5, wherein the calcination treatment is specifically: calcining the metal nano particle/polymer composite microsphere for 2-4 hours at the temperature of 400-550 ℃ in a nitrogen atmosphere; or calcining the inorganic oxide/polymer composite microspheres for 2-4 hours at 400-550 ℃ in a nitrogen atmosphere, and then calcining for 2-4 hours at 300-700 ℃ in an air atmosphere; or calcining the inorganic oxide/polymer composite microspheres for 2-4 hours at 400-550 ℃ in a nitrogen atmosphere.
10. The method according to claim 5, wherein the metal nanoparticle precursor is one of potassium tetrachloroplatinate, potassium tetrachloropalladate, tetrachloroauric acid, silver nitrate, cobalt chloride, and copper chloride; the inorganic oxide precursor is one of tetraethoxysilane, tetraisobutyl titanate, stannic chloride, zinc acetate and aluminum nitrate; the reducing agent is ascorbic acid or sodium borohydride.
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CN103241723A (en) * 2013-04-22 2013-08-14 华东师范大学 Preparation method of mesoporous carbon/silica composite nanoparticles
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