CN106745210B - A kind of Li adulterates SrTiO3The preparation method and product of porous surface nano particle - Google Patents

Abstract

The invention relates to a preparation method of Li-doped _SrTiO3 surface porous nanoparticles, comprising the following steps: 1) using titanium sulfate and potassium hydroxide as raw materials to prepare titanium hydroxide precipitation; 2) preparing strontium nitrate solution, Lithium sulfate solution, potassium hydroxide solution; the molar concentration of the strontium nitrate solution is 0.1～0.3mol/L, the molar concentration of the lithium sulfate solution is 0.05～0.1mol/L, and the molar concentration of the potassium hydroxide solution is 0.5～1.5 mol/L; 3) Stir and mix titanium hydroxide precipitation, strontium nitrate solution, potassium hydroxide solution and lithium sulfate solution to obtain a precursor, perform hydrothermal reaction, filter, wash, and dry to obtain Li-doped SrTiO ₃ surface porous nanoparticles. The preparation process is simple, the shape is easy to control, and the application is wide.

Description

A kind of preparation method and product of Li-doped SrTiO3 surface porous nanoparticles

technical field

The invention relates to the field of synthesis of inorganic materials, in particular to a preparation method and product of Li-doped _SrTiO3 surface porous nanoparticles.

Background technique

At present, the energy crisis and environmental pollution problems are becoming more and more serious around the world. Photocatalytic technology has the characteristics of low cost and environmental friendliness to solve this problem, so it needs to be vigorously developed. Strontium titanate can be used as a photocatalyst in environmental purification technologies such as photocatalytic treatment of water and gas-solid photocatalytic oxidation of environmental pollutants.

Strontium titanate (SrTiO ₃ ) is a typical perovskite compound, and its electronic properties can exhibit insulating, semiconducting, metallic, and even superconducting properties under certain conditions. As an electronic functional material, SrTiO ₃ has a high dielectric constant of about 330 and a low dielectric loss of 0.001 at room temperature at 50MHz.

At present, the traditional preparation methods of strontium titanate photocatalyst mainly include high-temperature solid-state reaction method, hydrothermal/solvothermal method, chemical co-precipitation method and sol-gel method, etc. The equipment and process of the solid-phase method are simple and convenient for industrial production, but the reaction temperature is high, and agglomeration is prone to occur, which is not conducive to the improvement of performance. The prepared photocatalyst products often need other experimental methods to improve their performance to meet high-standard use requirements. . The high-energy ball milling method is an improved solid-state reaction method. Although this method can prepare nanoscale strontium titanate, the product is still easy to agglomerate and introduce impurities. The sol-gel method has a lower calcination temperature (generally below 900°C), and the obtained particles have a smaller particle size, uniform distribution, and the process is easy to control, so it is more commonly used. Among various preparation methods, only the hydrothermal method does not require high-temperature treatment, and the synthesized powder has good dispersibility, and the shape of the synthesized powder particles can be regulated by changing the solvent, adjusting the temperature, reaction time, solution concentration, surface modifier, etc. The appearance and aggregation state are the methods used more in the preparation of nanoparticle strontium titanate photocatalysts in the current research work.

Chinese invention patent (CN 105883910 A) discloses a preparation method of perovskite SrTiO ₃ porous nanoparticles, including the following steps: 1) using titanium sulfate and potassium hydroxide as raw materials to prepare titanium hydroxide precipitation; 2) respectively Prepare strontium nitrate solution, potassium hydroxide solution and lithium nitrate solution; 3) mix titanium hydroxide precipitation, strontium nitrate solution, potassium hydroxide solution and lithium nitrate solution, and perform hydrothermal reaction to obtain perovskite SrTiO ₃ porous nanoparticles. In step 2), the lithium nitrate solution is used, and the NO ₃ ^- introduced in the hydrothermal process is combined with the K ⁺ in the potassium hydroxide solution to obtain KNO ₃ , and the ionization equilibrium constant of KNO ₃ is relatively large, so in the hydrothermal reaction process More K ⁺ enters the SrTiO ₃ particles, and the pores of SrTiO ₃ formed by doping lithium nitrate will run through the whole nanoparticle.

Contents of the invention

The object of the present invention is to address the deficiencies of the prior art, to provide a preparation method and product of Li-doped SrTiO ₃ surface porous nanoparticles, the preparation process is simple, the shape is easy to control, and it is widely used.

The technical scheme provided by the present invention is:

A preparation method of Li-doped _SrTiO3 surface porous nanoparticles, comprising the steps of:

1) using titanium sulfate and potassium hydroxide as raw materials to prepare titanium hydroxide precipitation;

2) prepare strontium nitrate solution, lithium sulfate solution, potassium hydroxide solution respectively; the molar concentration of described strontium nitrate solution is 0.1～0.3mol/L, the molar concentration of lithium sulfate solution is 0.05～0.1mol/L, potassium hydroxide The molar concentration of the solution is 0.5-1.5mol/L;

3) Stir and mix titanium hydroxide precipitation, strontium nitrate solution, potassium hydroxide solution, and lithium sulfate solution to obtain a precursor, perform hydrothermal reaction, filter, wash, and dry to obtain Li-doped SrTiO ₃ surface porous nanoparticles.

In the above technical scheme, titanium hydroxide precipitation is prepared by titanium sulfate and potassium hydroxide, and then the raw materials strontium nitrate, lithium sulfate, potassium hydroxide and titanium hydroxide precipitation are mixed through hydrothermal reaction to obtain Li-doped SrTiO ₃ Superficially porous nanoparticles. In the choice of lithium source, Li ₂ SO ₄ was chosen to replace LiNO ₃ because of the introduction of SO ₄ ^2- in the hydrothermal process. Compared with KNO ₃ under the same conditions, the ionization equilibrium constant of K ₂ SO ₄ is smaller, so in During the hydrothermal reaction, less K ⁺ enters the SrTiO ₃ particles, and the finally formed SrTiO ₃ particles will only form very shallow pores on the surface, and there are no pores in the interior, while the pores of SrTiO ₃ formed by doping lithium nitrate will run through the entire surface. nanoparticles.

Preferably, the mixing ratio of titanium hydroxide precipitation, strontium nitrate solution, potassium hydroxide solution and lithium sulfate solution in step 3) is 0.4-1.2g: 10-20ml: 5-15ml: 10-20ml.

Preferably, the reaction temperature of the hydrothermal reaction in the step 3) is 150-250° C., and the reaction time is 6-24 hours.

Preferably, the reaction temperature of the hydrothermal reaction in the step 3) is 190-210° C., and the reaction time is 20-24 hours. Through sufficient hydrothermal reaction for more than 20h, the crystallinity of the finally obtained Li-doped SrTiO ₃ surface porous nanoparticles can be better.

As a preference, the method for preparing the hydroxide precipitation of titanium in the step 1) is: respectively preparing a titanium sulfate solution with a molar concentration of 0.06 to 0.18 mol/L and a potassium hydroxide solution with a molar concentration of 5 to 10 mol/L; Potassium solution was added dropwise to titanium sulfate solution, and filtered to obtain titanium hydroxide precipitate. By controlling the preparation process of titanium hydroxide precipitation, the titanium hydroxide precipitation as raw material is more conducive to the preparation of Li-doped SrTiO ₃ surface porous nanoparticles.

Preferably, the dropping rate is 2-4 drops/second. The morphology of Li-doped _SrTiO3 superficially porous nanoparticles was further regulated by controlling the drop rate of potassium hydroxide solution into titanium sulfate solution.

Preferably, the mixing ratio of titanium hydroxide precipitation, strontium nitrate solution, potassium hydroxide solution and lithium sulfate solution in step 3) is 0.6-1g: 10-15ml: 10-15ml: 15-20ml. The morphology of Li-doped SrTiO ₃ superficially porous nanoparticles obtained under this mixing ratio is more regular and the size is more uniform.

As a preference, the cleaning method in step 3) is: washing the filtered product with dilute acetic acid and deionized water in sequence.

As a preference, the method for preparing the hydroxide precipitation of titanium in the step 1) is: respectively preparing a titanium sulfate solution with a molar concentration of 0.11 to 0.13 mol/L and a potassium hydroxide solution with a molar concentration of 7 to 9 mol/L; The potassium solution is added dropwise to the titanium sulfate solution at a rate of 2 to 4 drops/second, and filtered to obtain the titanium hydroxide precipitate; the molar concentration of the strontium nitrate solution in the step 2) is 0.15 to 0.18mol/L, and the lithium sulfate The molar concentration of the solution is 0.05～0.07mol/L, and the molar concentration of the potassium hydroxide solution is 0.9～1.1mol/L; In the step 3), the hydroxide precipitate of 0.7～0.9g titanium that will be washed, 14～ Add 16ml of strontium nitrate solution, 9-11ml of potassium hydroxide solution and 14-16ml of lithium sulfate solution into the reaction kettle, and carry out hydrothermal reaction at 190-200°C for 20-21 hours. Under the above conditions, the obtained Li-doped _SrTiO3 surface porous nanoparticles have good morphology, stable quality, high purity, and good particle dispersibility.

The present invention also provides a Li-doped SrTiO ₃ surface porous nanoparticle synthesized by the above-mentioned preparation method.

Compared with the prior art, the beneficial effect of the present invention is reflected in that the preparation method of the Li-doped SrTiO ₃ surface porous nanoparticles provided by the present invention has a simple preparation process, easy control of the shape, and wide application.

Description of drawings

Fig. 1 is the Li-doped SrTiO that embodiment ₁ prepares The XRD figure of surface porous nanoparticle;

Fig. 2 is the SEM figure of the Li-doped _SrTiO3 surface porous nanoparticles prepared by embodiment 1;

Fig. 3 is the Li-doped SrTiO that embodiment ₁ prepares The TEM figure of surface porous nanoparticle;

Fig. 4 is the Li-doped SrTiO that comparative example ₁ prepares The SEM figure of porous nanoparticle;

Fig. 5 is the Li-doped SrTiO that comparative example 1 prepares _The TEM figure of porous nanoparticle;

6 is a SEM image of Li-doped SrTiO ₃ cube nanoparticles prepared in Comparative Example 2.

Detailed ways

The present invention will be further described below in conjunction with specific embodiments and accompanying drawings.

Example 1

1) Dissolve 6 mmol of titanium sulfate and 0.16 mol of potassium hydroxide in deionized water respectively, adjust the molar concentration of the titanium sulfate solution to 0.12 mol/L, and the molar concentration of the potassium hydroxide solution to 8 mol/L.

2) Slowly drop 20ml of potassium hydroxide solution into 50ml of titanium sulfate solution under stirring at a rate of 2 drops/second to obtain white titanium hydroxide precipitate, let stand for 20min, filter and wash with deionized water Precipitate 3 times.

3) Dissolve strontium nitrate, potassium hydroxide and lithium sulfate in deionized water respectively, the molar concentration of strontium nitrate solution is 0.165mol/L, the molar concentration of potassium hydroxide solution is 1mol/L, and the concentration of lithium sulfate solution is 0.05 mol/L.

4) Add the cleaned 0.8g of titanium hydroxide precipitate, 15ml of strontium nitrate solution, 10ml of potassium hydroxide solution and 15ml of lithium sulfate solution into a 50ml reaction kettle, and adjust the total volume to the inner tank of the reaction kettle with deionized water. 40%, after stirring for 2 hours, heat treatment at 200°C for 20 hours. Then, cool down to room temperature, take out the reaction product, filter, wash with dilute acetic acid and deionized water in turn, and dry at 60°C to obtain Li-doped SrTiO ₃ surface porous nanoparticles.

Fig. 1 is the XRD pattern of the product obtained in Example 1, which shows that the product is perovskite SrTiO ₃ particles without other impurity peaks, indicating that the product is pure phase SrTiO ₃ .

The SEM photo of the scanning electron microscope is shown in Figure 2. The size of the prepared Li-doped SrTiO ₃ surface porous nanoparticles is between 300 and 350 nm, and the shape is a smooth transition porous cube, and many pores can be seen on the surface.

The TEM photo of the transmission electron microscope is shown in Figure 3, which proves that the prepared Li-doped SrTiO ₃ surface porous nanoparticles, the pores only exist on the surface of the particles, and there are no pores inside.

Example 2

1) Dissolve 7 mmol of titanium sulfate and 0.16 mol of potassium hydroxide in deionized water respectively, adjust the molar concentration of the titanium sulfate solution to 0.14 mol/L, and the molar concentration of the potassium hydroxide solution to 8 mol/L.

2) Slowly drop 20ml of potassium hydroxide solution into 50ml of titanium sulfate solution under stirring at a rate of 4 drops/second to obtain white titanium hydroxide precipitate, let stand for 20min, filter and wash with deionized water Precipitate 3 times.

3) Dissolve strontium nitrate, potassium hydroxide and lithium sulfate in deionized water respectively, the molar concentration of strontium nitrate solution is 0.165mol/L, the molar concentration of potassium hydroxide solution is 1mol/L, and the concentration of lithium sulfate solution is 0.08 mol/L.

4) Add the cleaned 0.8g of titanium hydroxide precipitate, 15ml of strontium nitrate solution, 10ml of potassium hydroxide solution and 15ml of lithium sulfate solution into a 50ml reaction kettle, and adjust the total volume to the inner tank of the reaction kettle with deionized water. 40%, after stirring for 2 hours, heat treatment at 200°C for 12 hours. Then, cool down to room temperature, take out the reaction product, filter, wash with dilute acetic acid and deionized water in turn, and dry at 60°C to obtain Li-doped SrTiO ₃ surface porous nanoparticles.

Example 3

1) Dissolve 7 mmol of titanium sulfate and 0.16 mol of potassium hydroxide in deionized water respectively, adjust the molar concentration of the titanium sulfate solution to 0.14 mol/L, and the molar concentration of the potassium hydroxide solution to 8 mol/L.

2) Slowly drop 20ml of potassium hydroxide solution into 50ml of titanium sulfate solution under stirring at a rate of 4 drops/second to obtain white titanium hydroxide precipitate, let stand for 20min, filter and wash with deionized water Precipitate 3 times.

3) Dissolve strontium nitrate, potassium hydroxide and lithium sulfate in deionized water respectively, the molar concentration of strontium nitrate solution is 0.165mol/L, the molar concentration of potassium hydroxide solution is 1mol/L, and the concentration of lithium sulfate solution is 0.1 mol/L.

4) Add the cleaned 0.8g of titanium hydroxide precipitate, 10ml of strontium nitrate solution, 10ml of potassium hydroxide solution and 20ml of lithium sulfate solution into a 50ml reactor, and use deionized water to adjust the total volume to that of the inner tank of the reactor. 40%, after stirring for 2 hours, heat treatment at 200°C for 6 hours. Then, cool down to room temperature, take out the reaction product, filter, wash with dilute acetic acid and deionized water in turn, and dry at 60°C to obtain Li-doped SrTiO ₃ surface porous nanoparticles.

Comparative example 1

1) Dissolve 6 mmol of titanium sulfate and 0.2 mol of potassium hydroxide in deionized water respectively, adjust the molar concentration of the titanium sulfate solution to 0.3 mol/L, and adjust the molar concentration of the potassium hydroxide solution to 8 mol/L.

2) Slowly drip the potassium hydroxide solution into the titanium sulfate solution in a stirred state at a rate of 4 drops/second to obtain white titanium oxide precipitates, let stand for 20 minutes, and centrifuge 4 to 5 times.

3) strontium nitrate, potassium hydroxide and lithium nitrate are dissolved in deionized water respectively, the molar concentration of strontium nitrate solution is 0.4mol/L, the molar concentration of potassium hydroxide solution is 2mol/L, and the molar concentration of lithium nitrate solution is 0.8mol/L.

4) Add the cleaned 0.8g of titanium oxide precipitate, 8ml of strontium nitrate solution, 13ml of potassium hydroxide solution and 8ml of lithium nitrate solution into a 50ml reaction kettle respectively, and adjust the total volume to be 100% of the inner tank of the reaction kettle with deionized water. 40%, after stirring for 2 hours, heat treatment at 200°C for 12 hours. Then, cool down to room temperature, take out the reaction product, add dilute acetic acid and deionized water to centrifuge for 4 to 5 times, and dry at 60° C. to obtain Li-doped SrTiO ₃ porous nanoparticles.

The SEM photo of the scanning electron microscope is shown in Figure 4. The size of the prepared Li-doped SrTiO ₃ porous nanoparticles ranges from 300 to 350 nm, and many pores can be seen at the same time.

The TEM photo of the transmission electron microscope is shown in Figure 5, which proves that the prepared Li-doped SrTiO ₃ porous nanoparticles have pores that run through the entire nanoparticle.

Comparative example 2

1) Dissolve 6 mmol of titanium sulfate and 0.16 mol of potassium hydroxide in deionized water respectively, adjust the molar concentration of the titanium sulfate solution to 0.12 mol/L, and the molar concentration of the potassium hydroxide solution to 8 mol/L.

2) Slowly drop 20ml of potassium hydroxide solution into 50ml of titanium sulfate solution under stirring at a rate of 2 drops/second to obtain white titanium hydroxide precipitate, let stand for 20min, filter and wash with deionized water Precipitate 3 times.

3) Dissolve strontium nitrate, potassium hydroxide and lithium sulfate in deionized water respectively, the molar concentration of strontium nitrate solution is 0.165mol/L, the molar concentration of potassium hydroxide solution is 1mol/L, and the concentration of lithium sulfate solution is 0.4 mol/L.

4) Add the cleaned 0.8g of titanium hydroxide precipitate, 15ml of strontium nitrate solution, 10ml of potassium hydroxide solution and 15ml of lithium sulfate solution into a 50ml reaction kettle, and adjust the total volume to the inner tank of the reaction kettle with deionized water. 40%, after stirring for 2 hours, heat treatment at 200°C for 20 hours. Then, cool down to room temperature, take out the reaction product, filter, wash with dilute acetic acid and deionized water in turn, and dry at 60°C to obtain Li-doped SrTiO ₃ cube nanoparticles.

The SEM photo of the scanning electron microscope is shown in Figure 6. The size of the prepared Li-doped SrTiO ₃ cube nanoparticles ranges from 300 to 350 nm, and there are no pores on the surface. Since the concentration of the lithium sulfate solution _used in step 4) is 0.4mol/L, as the concentration of _Li2SO4 increases, the number of Li ⁺ ions entering the crystal increases, while Li-O bonds have more covalent The bond composition has good directionality and saturation, which can promote the nucleation and growth of the intrinsic cubic structure of SrTiO ₃ . At the same time, the introduction of Li ⁺ ions will inhibit the entry of K + into the crystal, resulting in the reduction of pores until they disappear.

Claims (7)

1. a kind of Li adulterates SrTiO₃The preparation method of porous surface nano particle, which is characterized in that include the following steps：

1) using titanium sulfate and potassium hydroxide as raw material, the hydroxide precipitation of titanium is prepared；

2) strontium nitrate solution, lithium sulfate solution, potassium hydroxide solution are prepared respectively；The molar concentration of the strontium nitrate solution is 0.1~0.3mol/L, the molar concentration of lithium sulfate solution is 0.05~0.1mol/L, and the molar concentration of potassium hydroxide solution is 0.5~1.5mol/L；

3) hydroxide of titanium precipitation, strontium nitrate solution, potassium hydroxide solution and lithium sulfate solution are stirred to obtain forerunner Body carries out hydro-thermal reaction, filters, cleaning, is dried to obtain Li doping SrTiO₃Porous surface nano particle；The hydroxide of the titanium Object precipitation, strontium nitrate solution, potassium hydroxide solution and lithium sulfate solution mixed proportion be 0.4~1.2g：10~20mL：5~ 15mL ：10~20mL；The reaction temperature of the hydro-thermal reaction is 150~250 DEG C, the reaction time for 6~for 24 hours.

2. Li according to claim 1 adulterates SrTiO₃The preparation method of porous surface nano particle, which is characterized in that institute It is 190~210 DEG C to state the reaction temperature of hydro-thermal reaction in step 3), the reaction time for 20~for 24 hours.

3. Li according to claim 1 adulterates SrTiO₃The preparation method of porous surface nano particle, which is characterized in that institute State prepared in step 1) titanium hydroxide precipitation method be：The sulphur that molar concentration is 0.06~0.18mol/L is prepared respectively The potassium hydroxide solution of sour titanium solution and 5~10mol/L；Potassium hydroxide solution is added drop-wise in titanium sulfate solution, is obtained by filtration The hydroxide precipitation of titanium.

4. Li according to claim 3 adulterates SrTiO₃The preparation method of porous surface nano particle, which is characterized in that institute State 2~4 drops/sec of rate of addition.

5. Li according to claim 1 adulterates SrTiO₃The preparation method of porous surface nano particle, which is characterized in that institute The mixed proportion for stating the hydroxide precipitation of titanium in step 3), strontium nitrate solution, potassium hydroxide solution and lithium sulfate solution is 0.6 ~1g：10~15mL：10~15mL：15~20mL.

6. Li according to claim 1 adulterates SrTiO₃The preparation method of porous surface nano particle, which is characterized in that institute Stating cleaning method in step 3) is：The product being obtained by filtration is cleaned successively with spirit of vinegar, deionized water.

7. Li according to claim 1 adulterates SrTiO₃The preparation method of porous surface nano particle, which is characterized in that institute State prepared in step 1) titanium hydroxide precipitation method be：The sulphur that molar concentration is 0.11~0.13mol/L is prepared respectively The potassium hydroxide solution of sour titanium solution and 7~9mol/L；Potassium hydroxide solution is added drop-wise to sulfuric acid for 2~4 drops/sec with rate of addition In titanium solution, the hydroxide precipitation of titanium is obtained by filtration；

The molar concentration of strontium nitrate solution is 0.15~0.18mol/L in the step 2), and the molar concentration of lithium sulfate solution is 0.05~0.07mol/L, the molar concentration of potassium hydroxide solution is 0.9~1.1mol/L；

In the step 3) by the hydroxide of the 0.7~0.9g titaniums cleaned precipitation, 14~16mL strontium nitrate solutions, 9~ 11mL potassium hydroxide solutions and 14~16mL lithium sulfate solutions are added in reaction kettle, and it is anti-that hydro-thermal is carried out at 190~200 DEG C Answer 20~21h.