Mesoporous strontium titanate material, preparation method and application thereof

Abstract

The application discloses a preparation method of mesoporous strontium titanate material, which comprises the following steps: dissolving amphiphilic block copolymer and tetrabutyl titanate in N,N-dimethylformamide respectively, stirring to obtain solution A; dissolving strontium nitrate in deionized water, stirring to obtain solution B, mixing solution A with solution B, stirring to obtain light yellow transparent colloidal solution C; transferring and evaporating the light yellow transparent colloidal solution C, drying and solidifying to obtain an organic-inorganic composite film, and grinding to obtain a powder; and calcining the powder at 450-650 DEG C under a protective gas and then at 350-500 DEG C under an air atmosphere. The application further discloses the mesoporous strontium titanate obtained by the preparation method and application of the mesoporous strontium titanate in photocatalytic production of H2O2. The application can prepare 40 nm mesoporous strontium titanate material, and has the advantages of simple and convenient preparation method, low cost, and the like. The amount of H2O2 produced by photocatalysis reaches 95.2 muM (1 hour), which breaks through the bottleneck value of the prior art.

Description

TECHNICAL FIELD

[0001] The present application relates to mesoporous materials, their preparation and use, in particular to a mesoporous strontium titanate material, its preparation method and use. BACKGROUND

[0002] Energy issues are one of the major challenges facing today's society, and seeking sustainable energy conversion and utilization methods has become an urgent need. Photocatalysis as an emerging energy conversion technology can convert photon energy into chemical energy, such as water splitting to produce hydrogen, using sunlight. This process requires extremely high catalyst materials, and strontium titanate has become a material of great interest in the field of photocatalysis due to its excellent photoelectric properties and catalytic activity. Mesoporous materials as a key nanomaterial have attracted widespread interest in the field of materials science and nanotechnology in recent years. This material has important potential in various applications due to its highly ordered pore structure, high specific surface area, and adjustable pore size (see Advanced Materials 32.44 (2020): 2004654.).

[0003] Strontium titanate (SrTiO3) is an important perovskite material with wide application prospects, especially in the field of photocatalysis. Its crystal structure is stable, and it has excellent photoelectric properties, good light absorption and electron transport performance, making it an ideal candidate for photocatalytic materials (see Nature Electronics (2023): 1-8.). However, traditional strontium titanate crystals have micron-sized dimensions, which have small surface areas and limited photoelectric conversion efficiency, limiting their application in photocatalysis.

[0004] In order to achieve sustainable application in the field of photocatalysis, further research is needed on the preparation, performance control and practical application of mesoporous strontium titanate. Chinese patent No. 201610396008.3 discloses a method for preparing ordered mesoporous strontium titanate, but the method is complex, requires the pre-synthesis of phenolic resin, and has a high cost. The carbon residue of the phenolic resin during subsequent calcination affects the photocatalytic H2O2 production performance. The material has a small pore size (<5 nm) and is not adjustable, which affects the mass transfer rate of guest molecules in the pore. The patent also does not evaluate the photocatalytic performance of the material. At the same time, the existing porous catalyst (MoS2) has a maximum photocatalytic H2O2 production of 62.3 μM, which needs to be further improved. SUMMARY

[0005] Invention purposes: In order to overcome the deficiencies in the prior art, the purpose of the present application is to provide a preparation method of mesoporous strontium titanate material with lower cost, controllable pore size and wall thickness, another purpose of the present application is to provide a mesoporous strontium titanate material with large specific surface area, rich adsorption active sites and high crystallinity, and still another purpose of the present application is to provide an application of mesoporous strontium titanate material in photocatalytic production of H2O2.

[0006] Technical scheme: The preparation method of the mesoporous strontium titanate material comprises the following steps:

[0007] Step one, the amphiphilic block copolymer and tetrabutyl titanate are respectively dissolved in N,N-dimethylformamide to obtain solution A by stirring; strontium nitrate is dissolved in deionized water to obtain solution B by stirring, and solution A and solution B are mixed to obtain a light yellow transparent colloidal solution C by stirring;

[0008] Step two, the light yellow transparent colloidal solution C is transferred and volatilized, dried and solidified to obtain an organic-inorganic composite film, and the organic-inorganic composite film is ground to obtain a powder;

[0009] Step three, the powder obtained in step two is first calcined at 450-650 DEG C under a protective gas, and then calcined at 350-500 DEG C in an air atmosphere to obtain the mesoporous strontium titanate material.

[0010] Further, in step one, the amphiphilic block copolymer comprises a hydrophilic segment and a hydrophobic segment, the molecular weight of the hydrophilic segment is 2500-5000 g / mol, and the molecular weight of the hydrophobic segment is 5000-35000 g / mol. The amphiphilic block copolymer is one or more of polystyrene-polyethylene oxide (PS-b-PEO), polybutadiene-polyethylene oxide (PB-b-PEO), polystyrene-poly-4-vinylpyridine (PS-b-P4VP), polyethylene oxide-poly-methyl methacrylate (PEO-b-PMMA), and polyacrylic acid-polystyrene (PAA-b-PS). The mass ratio of the amphiphilic block copolymer to strontium nitrate is 1:2-4, the molar ratio of tetrabutyl titanate to strontium nitrate is equimolar, and the volume ratio of deionized water to N,N-dimethylformamide is 1:5-50.

[0011] Preferably, the molar ratio of tetrabutyl titanate to strontium nitrate (Ti: Sr ratio) is 1:1, the mass ratio of deionized water to strontium nitrate is 5:1, the volume ratio of deionized water to N,N-dimethylformamide (DMF) is 1:9, the M n of the amphiphilic block copolymer is 9000-37500 g / mol, preferably 20000-37500.

[0012] Further, in step two, the volatilization temperature is 40-60℃, and the time is 12-24h.

[0013] Further, in step three, the protective gas is argon or nitrogen; the calcination temperature is 1-5℃ / min, and the calcination time is 1-3h.

[0014] Preferably, the calcination temperature is 450-650℃ under the protective gas at a temperature increasing rate of 1℃ / min, and the calcination temperature is 350-500℃ under the air atmosphere at a temperature increasing rate of 5℃ / min.

[0015] The mesoporous strontium titanate material is obtained by the preparation method.

[0016] Further, the greater the molecular weight of the hydrophilic block of the amphiphilic block copolymer, the thicker the pore wall thickness of the mesoporous strontium titanate material; the greater the molecular weight of the hydrophobic block of the amphiphilic block copolymer, the greater the pore size of the mesoporous strontium titanate material. 5k -b-PS 15k The corresponding pore wall thickness is 5nm, and the pore size is 15nm.

[0017] The mesoporous strontium titanate material is used in the application of photocatalytic production of H2O2.

[0018] Preparation principle: the amphiphilic block copolymer is used as an organic template agent, tetrabutyl titanate and strontium nitrate are used as inorganic precursors, DMF and H2O are used as solvents, solvent volatilization induced self-assembly (EISA) is used to make the template agent act on the organic precursor and the inorganic precursor to form microphase separation and form mesostructure, so as to synthesize mesoporous strontium titanate; the hydrophobic segment of the amphiphilic block copolymer is aggregated in the solvent to form a spherical micelle with the hydrophobic segment as the core and the hydrophilic segment as the shell, the template agent is removed by calcination under Ar / N2 atmosphere protection, the inorganic precursor is decomposed, and the mesoporous strontium titanate material is obtained after calcination in air and removal of carbon.

[0019] Mesoporous structure is introduced to improve the photocatalytic performance of strontium titanate. Mesoporous structure has high specific surface area and adjustable pore size, which can enhance the adsorption capacity and reaction activity of the material. In the field of photocatalysis, mesoporous structure is expected to provide more active sites, improve light absorption, improve carrier separation and transport, and thus improve photocatalytic efficiency. In addition, mesoporous strontium titanate material is successfully prepared by template method. Template method can construct highly ordered pore structure through self-assembly of template agent and subsequent heat treatment. This method allows precise control of pore size and pore structure, which helps to optimize photocatalytic performance. By controlling the molecular weight of the hydrophobic block of the block copolymer, the mesoporous pore size and specific surface area of the material can be effectively controlled. By changing the length of the hydrophilic block of the amphiphilic block copolymer, the wall thickness of the synthesized ordered mesoporous strontium titanate can be controlled.

[0020] Advantages: Compared with the prior art, the present application has the following remarkable features:

[0021] 1. Mesoporous strontium titanate material with a pore size of 40 nm can be prepared, the method is simple and convenient, the cost is low, and the amount of H2O2 produced by photocatalysis can reach 95.2 μM, breaking through the bottleneck value of the prior art;

[0022] 2. The synthesis method of the ordered mesoporous strontium titanate using the amphiphilic block copolymer as a structure guide is universal and can be applied to various amphiphilic block copolymers such as PS-b-PEO, PB-b-PEO, PS-b-P4VP, PEO-b-PMMA, PAA-b-PS, etc., which is convenient for synthesis according to needs;

[0023] 3. The hydrophilic block in the block copolymer can interact with tetrabutyl titanate through hydrogen bonding to form uniform spherical micelles, which are then self-assembled into ordered mesostructure during the subsequent solvent evaporation process;

[0024] 4. The obtained mesoporous strontium titanate material has large specific surface area, rich adsorption active sites, high crystallinity, controllable pore size and wall thickness, and is expected to be widely used in the fields of catalysis, sensing, energy, etc., especially in the photocatalytic production of H2O2. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 SEM pattern of mesoporous SrTiO3 prepared in Example 1 of the present application.

[0026] Figure 2 XRD pattern of mesoporous SrTiO3 prepared in Example 1 of the present application.

[0027] Figure 3 Ultraviolet light absorption spectrum of mesoporous SrTiO3 prepared in Example 1 of the present application.

[0028] Figure 4 These are the graphs showing the change in H2O2 concentration over time for the mesoporous SrTiO3 obtained in this invention and the non-porous SrTiO3 obtained in Comparative Example 1.

[0029] Figure 5 This is a spectrum of the photocatalytic H2O2 production performance of mesoporous SrTiO3 at different calcination temperatures according to the present invention. Detailed Implementation

[0030] In the following examples, strontium nitrate (Sr(NO3)2), tetrabutyl titanate (TBOT), N,N-dimethylformamide (DMF), hydrochloric acid, acetic acid, KI, and potassium hydrogen phthalate were purchased from Shanghai Aladdin Reagent Co., Ltd. The amphiphilic block copolymer polystyrene-polyethylene oxide (PS) 5～35k -b-PEO 2.5k～5k ), polybutadiene-polyethylene oxide (PB) 5～35k -b-PEO 2.5k～5k ), polystyrene-poly4-vinylpyridine (PS) 5～35k -b-P4VP 2.5k～5k ), polyethylene oxide-polymethyl methacrylate (PEO) 2.5k～5k -b-PMMA 5～35k ), polyacrylic acid-polystyrene (PAA) 2.5k～5k -b-PS 5～35k All components were purchased from PolymerSource, USA. The amphiphilic block copolymers consist of hydrophilic and hydrophobic segments. The hydrophilic segments (PEO, P4VP, PAA) have a molecular weight of 2500–5000 g / mol, denoted as 2.5k–5k; the hydrophobic segments (PS, PMMA, PB) have a molecular weight of 5000–35000 g / mol, denoted as 5k–35k. Amphiphilic block copolymers with different molecular weights can be customized according to requirements. The tube furnace is a Tianjin Zhonghuan tube atmosphere furnace.

[0031] Example 1

[0032] A method for preparing mesoporous strontium titanate material includes the following steps:

[0033] (1) 0.10 g of amphiphilic block copolymer polystyrene-polyethylene oxide (PS) 15k -b-PEO 5k Mn = 20000 gmol -1) was dissolved in 5 mL DMF, 0.15 mL hydrochloric acid, 0.15 mL acetic acid were added dropwise, and stirred for 5 min. Then 0.48 mL TBOT was added dropwise, and stirred to obtain a homogeneous solution A. Meanwhile, 0.3 g Sr(NO3)2was dissolved in 1 mL deionized water, and stirred to obtain a homogeneous solution B. Solution B was added dropwise to solution A, and stirred to obtain a light yellow transparent colloidal solution C.

[0034] (2) The light yellow transparent colloidal solution C was transferred to a culture dish, and volatilized at 40°C for 12 h. The culture dish was transferred to a 100°C oven for further volatilization of the solvent, and solidified for 24 h to obtain a transparent organic-inorganic composite film. The organic-inorganic composite film was scraped off from the culture dish to obtain a white powder.

[0035] (3) The white powder obtained in step (2) was placed in a tube furnace, and calcined at 550°C for 2 h under Ar atmosphere, with a heating rate of 1.0°C / min. The sample was cooled to room temperature, and then calcined at 400°C for 1 h in air, with a heating rate of 5°C / min, to obtain a white mesoporous SrTiO3powder.

[0036] The mesoporous SrTiO3material prepared in this example was characterized by scanning electron microscopy, and the results are shown in Figure 1 . As can be seen from Figure 1 , the mesoporous strontium titanate material obtained in this example has a clear mesoporous structure, with a pore size of 15 nm and a pore wall thickness of 5 nm.

[0037] The mesoporous SrTiO3prepared in this example was analyzed by X-ray diffraction, and the results are shown in Figure 2 . As can be seen from Figure 2 , the SrTiO3prepared in this example (PDF #00-035-0734) shows three clear diffraction peaks corresponding to the (110), (220), and (221) crystal planes, indicating that a highly crystalline mesoporous SrTiO3material is obtained.

[0038] Example 2

[0039] A method for preparing a mesoporous strontium titanate material, comprising the following steps:

[0040] (1) 0.10 g of an amphiphilic block copolymer, polyethylene oxide-poly(methyl methacrylate) (PEO 3k -b-PMMA 20k , Mn = 23000 g / mol -1Dissolve 0.2 g of Sr(NO3)2 in 15 mL of DMF, then add 0.15 mL of hydrochloric acid and 0.15 mL of acetic acid dropwise, stirring for 5 min. Next, add 0.32 mL of TBOT dropwise, stirring to obtain a homogeneous solution A. Simultaneously, dissolve 0.2 g of Sr(NO3)2 in 1 mL of deionized water, stirring to obtain a homogeneous solution B. Add solution B dropwise to solution A, stirring continuously, to obtain a pale yellow, transparent colloidal solution C.

[0041] (2) The pale yellow transparent colloidal solution C was transferred to a petri dish and evaporated at 40°C for 12 hours. The petri dish was then transferred to a 100°C oven for further solvent evaporation and curing for 24 hours to obtain a transparent organic-inorganic composite film. The organic-inorganic composite film was scraped off the petri dish to obtain a white powder.

[0042] (3) The white powder obtained in step (2) was placed in a tube furnace and calcined at 450°C for 2 hours under an Ar atmosphere at a heating rate of 1.0°C / min. The powder was then cooled to room temperature to obtain a black sample. The sample was then calcined in air at 400°C for 1 hour at a heating rate of 5°C / min to obtain white mesoporous SrTiO3 powder.

[0043] The mesoporous strontium titanate material obtained in this embodiment has a pore size of 20 nm and a pore wall thickness of 3 nm.

[0044] Example 3

[0045] A method for preparing mesoporous strontium titanate material includes the following steps:

[0046] (1) 0.10 g of the amphiphilic block copolymer polybutadiene-polyethylene oxide (PB) 25k -b-PEO 4k Mn = 29000 gmol -1 Dissolve 0.25 g of Sr(NO3)2 in 10 mL of DMF, then add 0.15 mL of hydrochloric acid and 0.15 mL of acetic acid dropwise, stirring for 5 min. Next, add 0.4 mL of TBOT dropwise, stirring to obtain a homogeneous solution A. Simultaneously, dissolve 0.25 g of Sr(NO3)2 in 1 mL of deionized water, stirring to obtain a homogeneous solution B. Add solution B dropwise to solution A, stirring continuously, to obtain a pale yellow, transparent colloidal solution C.

[0047] (2) The pale yellow transparent colloidal solution C was transferred to a petri dish and evaporated at 50°C for 12 hours. The petri dish was then transferred to a 100°C oven for further solvent evaporation and curing for 24 hours to obtain a transparent organic-inorganic composite film. The organic-inorganic composite film was scraped off the petri dish to obtain a white powder.

[0048] (3) The white powder obtained in step (2) was placed in a tube furnace and calcined at 450°C for 2h under Ar atmosphere at a heating rate of 1.0°C / min, and then cooled to room temperature. The obtained sample was calcined at 400°C for 1h under air atmosphere at a heating rate of 5°C / min, and a white mesoporous SrTiO3 powder was obtained.

[0049] The mesoporous SrTiO3 material obtained in this example has a pore size of 25nm and a pore wall thickness of 4nm.

[0050] Example 4

[0051] The remaining steps of this example are the same as those of Example 3, except that the calcination temperature is replaced by 550°C under Ar atmosphere.

[0052] The mesoporous SrTiO3 material obtained in this example has a pore size of 20nm and a pore wall thickness of 6nm.

[0053] Example 5

[0054] The remaining steps of this example are the same as those of Example 3, except that the calcination temperature is replaced by 650°C under Ar atmosphere.

[0055] The mesoporous SrTiO3 material obtained in this example has a pore size of 15nm and a pore wall thickness of 8nm.

[0056] Comparative Example 1

[0057] A method for preparing a white non-porous SrTiO3 powder comprises the following steps:

[0058] (1) 0.15mL of hydrochloric acid and 0.15mL of acetic acid were added dropwise into 10mL of DMF, and stirred for 5min. Then 0.3mL of TBOT was added dropwise into the mixture, and stirred to obtain a uniform solution A. Meanwhile, 0.185g of Sr(NO3)2 was dissolved into 1mL of deionized water, and stirred to obtain a homogeneous solution B. Solution B was added dropwise into solution A, and stirred to obtain a transparent colorless colloidal solution C.

[0059] (2) The transparent colloidal solution C was transferred into a culture dish, and volatilized at 40°C for 12h. The culture dish was transferred into an oven at 100°C for further volatilization of the solvent, and solidified for 24h to obtain a transparent organic-inorganic composite film. The organic-inorganic composite film was scraped from the culture dish to obtain a white powder.

[0060] (3) The white powder obtained in step (2) was placed in a tube furnace and calcined at 550°C for 2h under Ar atmosphere at a heating rate of 1.0°C / min, and then cooled to room temperature. The obtained sample was calcined at 400°C for 1.0h under air atmosphere at a heating rate of 5°C / min, and a white non-porous SrTiO3 powder was obtained.

[0061] Photocatalytic H2O2 production performance determination:

[0062] The white mesoporous SrTiO3 powders obtained in Examples 1-5 and the white non-porous SrTiO3 powder obtained in Comparative Example 1 were respectively applied to photocatalytic water splitting, and their comprehensive water splitting H2O2 production performance was tested, to compare the effects of calcination temperature, template agent, etc. on the photocatalytic H2O2 production performance of mesoporous SrTiO3.

[0063] H2O2 standard curve preparation: H2O2 with concentrations of 100 μmol / L, 200 μmol / L, 400 μmol / L, and 500 μmol / L was respectively prepared, and then KI+potassium hydrogen phthalate (C8H5O4K) titration was used to test the absorbance of H2O2 at each concentration, to obtain the H2O2 standard curve.

[0064] The specific test steps are as follows:

[0065] (1) H2O2 determination: 50 mg of the above photocatalyst (Examples 1, 2, 3, and 4) was weighed into a 50 mL beaker, 5 mL of isopropyl alcohol was added, 45 mL of deionized water was added, and then ultrasonic treatment was performed for 2-3 min, to make the photocatalyst uniformly distributed in the solution.

[0066] (2) After connecting the reaction device in the photocatalytic reaction tank, the condensate water was turned on, oxygen was continuously supplied during the reaction, the xenon lamp light source was turned on, the experiment was performed under ultraviolet light, and then KI+potassium hydrogen phthalate (C8H5O4K) was used to test the concentration of H2O2. According to the change in the H2O2 generation concentration, the sample with the highest activity was found. At 15 min, 30 min, 45 min, and 60 min of the reaction, 3 mL of sample was taken from the reaction tank each time, and was placed in sample tubes numbered 1, 2, 3, and 4, respectively, and then was centrifuged in a centrifuge tube for 5 min.

[0067] (3) 2 mL of supernatant of the centrifuged sample was taken and added to 4 sample tubes containing 0.5 mL of KI+0.5 mL of C8H5O4K, and was mixed uniformly, and was reacted for 4-6 h. Then a small amount of solution was taken from each of the 4 volumetric flasks and was placed in a cuvette, and the absorbance was measured using a UV spectrophotometer.

[0068] According to the above standard curve, the H2O2 generation amount was calculated, to obtain the ultraviolet light absorbance curve. Figure 3 .

[0069] From Figure 3It can be seen that the UV light absorption spectrum of the mesoporous SrTiO3 prepared in Example 1 shows that the amount of H2O2 generated by the mesoporous SrTiO3 as a photocatalyst continuously increases within one hour, and the mesoporous SrTiO3 has sustained photocatalytic performance.

[0070] As Figure 4 can be seen from Table 1, the photocatalytic H2O2 production performance of the mesoporous strontium titanate (SrTiO3) prepared in Example 1, Example 2 changes with the molecular weight of the template agent, and the molecular weight of the template agent should not be too large. The photocatalytic H2O2 production performance of the mesoporous strontium titanate synthesized in Example 1 is the best, and the H2O2 concentration in one hour is 95.2 μM. Figure 4 In the table, Comparative Example 1 is a non-porous SrTiO3 as a control group, and it can be obviously seen that its performance is much lower than the photocatalytic H2O2 production performance of the mesoporous SrTiO3.

[0071] As Figure 5 can be seen from Table 1, the photocatalytic H2O2 production performance of the mesoporous strontium titanate (SrTiO3) prepared in Example 1, Example 2 changes with the molecular weight of the template agent, and the molecular weight of the template agent should not be too large. The photocatalytic H2O2 production performance of the mesoporous strontium titanate synthesized in Example 1 is the best, and the H2O2 concentration in one hour is 95.2 μM.

[0072] Table 1 Photocatalytic H2O2 production performance of different photocatalysts

[0073]

[0074] As can be seen from Table 1, the photocatalytic H2O2 production performance of the mesoporous SrTiO3 prepared in Example 1 is better than that of other kinds of metal oxide photocatalysts (see ACS Catalysis 6.8 (2016): 4976-4982. (BiVO4, Au 0.2 / TiO2, Au 0.2 / WO3), Journal of Catalysis 345 (2017): 78-86. (CdS-graphene), Catalysis Science & Technology 8.6 (2018): 1686-1695. (g-C3N4-SiW 11 ), Journal of Catalysis 376 (2019): 198-208 (MoS2)).

[0075] Example 6

[0076] A preparation method of a mesoporous strontium titanate material, comprising the following steps:

[0077] (1) 0.10 g of an amphiphilic block copolymer polystyrene-poly-4-vinylpyridine (PS 35k -b-P4VP2.5k Mn = 37500 g mol -1 ) was dissolved in 50 mL DMF, 0.15 mL hydrochloric acid, 0.15 mL acetic acid was added dropwise, and stirred for 5 min. Then 0.64 mL TBOT was added dropwise, and stirred to get a homogeneous solution A. Meanwhile, 0.4 g Sr(NO3)2was dissolved in 1 mL deionized water, and stirred to get a homogeneous solution B. Solution B was added dropwise to solution A, and stirred to get a light yellow transparent colloidal solution C.

[0078] (2) The light yellow transparent colloidal solution C was transferred to a culture dish, and volatilized at 60°C for 24 h. The culture dish was transferred to a 150°C oven for further volatilization of the solvent, and solidified for 12 h to obtain a transparent organic-inorganic composite film. The organic-inorganic composite film was scraped from the culture dish to obtain a white powder.

[0079] (3) The white powder obtained in step (2) was placed in a tube furnace, and calcined at 500°C for 2 h under N2atmosphere, with a heating rate of 1.0°C / min. The sample was cooled to room temperature, and then calcined at 350°C for 1 h in air, with a heating rate of 5°C / min, to obtain a white mesoporous SrTiO3powder.

[0080] The mesoporous strontium titanate material obtained in the example has a pore size of 35 nm and a pore wall thickness of 2.5 nm.

[0081] Example 7

[0082] A method for preparing a mesoporous strontium titanate material, comprising the following steps:

[0083] (1) 0.10 g of an amphiphilic block copolymer polyacrylic acid-polystyrene (PAA 4k -b-PS 5k , Mn = 9000 g mol -1 ) was dissolved in 30 mL DMF, 0.15 mL hydrochloric acid, 0.15 mL acetic acid was added dropwise, and stirred for 5 min. Then 0.56 mL TBOT was added dropwise, and stirred to get a homogeneous solution A. Meanwhile, 0.35 g Sr(NO3)2was dissolved in 1 mL deionized water, and stirred to get a homogeneous solution B. Solution B was added dropwise to solution A, and stirred to get a light yellow transparent colloidal solution C.

[0084] (2) The light yellow transparent colloidal solution C was transferred to a culture dish, and volatilized at 55°C for 18 h. The culture dish was transferred to a 130°C oven for further volatilization of the solvent, and solidified for 20 h to obtain a transparent organic-inorganic composite film. The organic-inorganic composite film was scraped from the culture dish to obtain a white powder.

[0085] (3) The white powder obtained in step (2) was placed in a tube furnace and calcined at 600°C for 2h under N2atmosphere with a heating rate of 1.0°C / min. The sample was cooled to room temperature and then calcined at 500°C for 1h under air with a heating rate of 5°C / min to obtain a white mesoporous SrTiO3powder.

[0086] The mesoporous SrTiO3material obtained in this example has a pore size of 5nm and a pore wall thickness of 4nm.

[0087] Example 8

[0088] The remaining steps of this example are the same as those of Example 3, except that the block copolymer is PS-b-PEO. 25k -b-PEO 10k .

[0089] The mesoporous SrTiO3material obtained in this example has a pore size of 25nm and a pore wall thickness of 10nm.

[0090] In the above examples, Example 1 is the optimal example.

[0091] Comparative Example 2

[0092] The remaining steps of this example are the same as those of Example 1, except that the mass ratio of the amphiphilic block copolymer to strontium nitrate in step (1) is 1:1. It was found that the mesoporous SrTiO3material could not be successfully prepared.

[0093] Comparative Example 3

[0094] The remaining steps of this example are the same as those of Example 1, except that the mass ratio of the amphiphilic block copolymer to strontium nitrate in step (1) is 1:5. It was found that the mesoporous SrTiO3material could not be successfully prepared.

[0095] Comparative Example 4

[0096] The remaining steps of this example are the same as those of Example 1, except that the calcination temperature under Ar atmosphere in step (3) is replaced by 400°C and the calcination temperature under air is replaced by 300°C. It was found that the mesoporous SrTiO3material has a low degree of crystallinity and the organic template cannot be completely decomposed.

[0097] Comparative Example 5

[0098] The remaining steps of this example are the same as those of Example 1, except that the calcination temperature under Ar atmosphere in step (3) is replaced by 700°C and the calcination temperature under air is replaced by 550°C. It was found that the mesoporous structure of the SrTiO3material collapses and the specific surface area decreases due to grain growth.

Claims

1. A method for preparing a mesoporous strontium titanate material, characterized in that, The method comprises the following steps: Step one, amphiphilic block copolymer, tetrabutyl titanate are dissolved in N, N-dimethylformamide respectively, stirring to obtain solution A; strontium nitrate is dissolved in deionized water, stirring to obtain solution B, mixing solution A and solution B, stirring to obtain light yellow transparent colloidal solution C; Step two, light yellow transparent colloidal solution C is transferred to volatilize, dry and solidify to obtain an organic-inorganic composite film, grinding the organic-inorganic composite film to obtain a powder; Step three, the powder obtained in step two is calcined at 450~650℃ under a protective gas, and then calcined at 350~500℃ under an air atmosphere to obtain a mesoporous strontium titanate material; In the step one, the mass ratio of amphiphilic block copolymer to strontium nitrate is 1:2~4, tetrabutyl titanate and strontium nitrate are equimolar, and the volume ratio of deionized water to N, N-dimethylformamide is 1:5~50; In the step two, the volatilization temperature is 40~60℃, and the time is 12~24h; In the step one, the amphiphilic block copolymer comprises a hydrophilic segment and a hydrophobic segment, the molecular weight of the hydrophilic segment is 2500~5000g / mol, and the molecular weight of the hydrophobic segment is 5000~35000g / mol; In the step one, the amphiphilic block copolymer is one or more of polystyrene-polyethylene oxide, polybutadiene-polyethylene oxide, polystyrene-poly-4-vinylpyridine, polyethylene oxide-poly-methyl methacrylate, and polyacrylic acid-polystyrene.

2. The method for preparing a mesoporous strontium titanate material according to claim 1, characterized in that: In the step two, the drying and solidification temperature is 100~150℃, and the time is 12~24h.

3. The method for preparing a mesoporous strontium titanate material according to claim 1, characterized in that: In the step three, the protective gas is argon or nitrogen; the calcination heating rate is 1~5℃ / min, and the calcination time is 1~3h.

4. A mesoporous strontium titanate material, characterized by: The mesoporous strontium titanate material is obtained by the preparation method of any one of claims 1~3; the pore size of the mesoporous strontium titanate material is 5~40 nm, and the pore wall thickness is 2~10 nm.

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