Preparation method of amorphous tungsten oxide nanomaterial
By precisely controlling the material ratio and temperature parameters, and combining inexpensive raw materials and macromolecular chain organic stabilizers, the problems of uneven morphology, unstable structure and poor dispersibility in the preparation of amorphous tungsten oxide nanosheets have been solved, realizing low-cost and efficient preparation of amorphous tungsten oxide nanosheets suitable for optoelectronic, catalytic and energy storage fields.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- BEIHANG UNIV
- Filing Date
- 2026-03-03
- Publication Date
- 2026-07-31
AI Technical Summary
Existing methods for preparing amorphous tungsten oxide nanosheets suffer from problems such as poor product morphology and size uniformity, difficulty in maintaining stable amorphous structure, high preparation cost and insufficient adaptability, and poor dispersion stability, which limit their large-scale application in optoelectronics, catalysis, energy storage and other fields.
By precisely controlling the material ratio, temperature parameters, and stabilizer introduction method during the reaction process, and using inexpensive chemical raw materials such as ammonium paratungstate and sodium dodecylbenzenesulfonate, combined with stepwise heating and macromolecular chain organic stabilizers, amorphous tungsten oxide nanosheets are prepared, ensuring that the product morphology is controllable, the amorphous structure is stable, and the dispersion performance is excellent.
A low-cost and efficient preparation of amorphous tungsten oxide nanosheets was achieved, which have regular morphology, uniform size distribution and high dispersibility, and are suitable for application needs in multiple fields. This reduces production costs and improves the performance stability and applicability of the material.
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Figure CN122482508A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of nanomaterial preparation technology, specifically relating to a solvothermal preparation process for amorphous tungsten oxide nanosheets, which is applicable to the large-scale preparation of amorphous tungsten-based nanomaterials in fields such as photocatalytic materials, gas sensors, and energy storage electrode materials. Background Technology
[0002] Tungsten oxide is a semiconductor material with multiple functions such as photoelectric, catalysis, and energy storage. Among them, amorphous tungsten oxide nanosheets, due to their amorphous structure, abundant active sites, high specific surface area, and excellent ion transport capabilities, have shown far greater application potential than crystalline tungsten oxide in fields such as photocatalytic degradation of pollutants, gas sensors, and lithium-ion battery anode materials.
[0003] Currently, the main methods for preparing amorphous tungsten oxide nanomaterials include the sol-gel method, hydrothermal / solvothermal method, and template method. Among these, the solvothermal method has become one of the mainstream technologies for preparing amorphous tungsten oxide nanosheets due to its advantages such as mild reaction conditions and easy control of product morphology. However, existing solvothermal preparation processes still have many problems that urgently need to be solved:
[0004] First, the morphology and size uniformity of the product are poor. Traditional processes often directly mix tungsten sources with surfactants, lacking precise control over the hydrolysis and polymerization processes of the tungsten source. This easily leads to problems such as agglomeration, uneven size distribution, and large differences in layer thickness in the generated tungsten oxide nanosheets, seriously affecting the material's performance stability. Second, the amorphous structure is difficult to maintain stably. Crystalline tungsten oxide has higher thermodynamic stability than amorphous tungsten oxide. During solvothermal high-temperature reactions, without effective control methods, the amorphous phase easily transforms into the crystalline phase, leading to an increased crystallinity of the final product and the loss of the unique performance advantages of the amorphous structure. Third, the adaptability of the preparation process is insufficient. Some existing technologies require the introduction of expensive special template agents or complex post-processing to improve the controllability of product morphology, which not only increases raw material costs and preparation cycles but also makes it difficult to meet the needs of large-scale production. Other processes suppress crystallization by lowering the reaction temperature and shortening the reaction time, but this leads to insufficient crystallinity and low purity of the product, which also limits its industrial application. Fourth, the dispersion stability is poor. Tungsten oxide nanosheets are prone to secondary agglomeration during preparation and storage due to their high surface energy. Existing processes often improve dispersibility by adding a single small molecule stabilizer. However, small molecule stabilizers are prone to desorption, making it difficult to achieve long-term stable coating of nanosheets, which in turn affects the processing and application of subsequent materials.
[0005] In summary, developing a method for preparing amorphous tungsten oxide nanosheets that is low in raw material cost, high in preparation efficiency, and produces products with uniform morphology and stable amorphous structure is key to promoting its large-scale application in optoelectronics, catalysis, energy storage, and other fields, and is also a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention
[0006] To address the shortcomings of existing solvothermal preparation processes for amorphous tungsten oxide nanosheets, such as poor product morphology and size uniformity, difficulty in maintaining stable amorphous structures, high preparation costs and insufficient adaptability, and poor dispersion stability, this invention aims to provide a solvothermal method for preparing amorphous tungsten oxide nanosheets. By precisely controlling the material ratio, temperature parameters, and stabilizer introduction method during the reaction process, this method achieves efficient and low-cost preparation of amorphous tungsten oxide nanosheets while ensuring controllable product morphology, stable amorphous structure, and good dispersion performance, thus meeting the needs of large-scale production and subsequent applications.
[0007] This invention prepares an amorphous tungsten oxide nanosheet, comprising the following steps:
[0008] Step 1: Dissolve tungsten salt in water and stir until dissolved to obtain precursor solution A;
[0009] Step 2: Dissolve the surfactant in water and stir until it is completely dissolved to obtain solution B;
[0010] Step 3: Stir solution B, adjust the pH of the solution, and simultaneously raise the temperature to 70~80℃ using a step-by-step heating method; while maintaining this temperature and stirring, slowly add precursor solution A dropwise to solution B, and continue the reaction for 1 h after the addition is complete;
[0011] Step 4: Add an aqueous solution of macromolecular chain organic stabilizer to the pH-adjusted solution and mix thoroughly; place the mixture in an environment of 20~40℃ and sonicate for 10~40 min.
[0012] Step 5: After ultrasonic treatment, heat the system to 80°C and continue stirring at this temperature for 5 hours to obtain a colorless and transparent mixture.
[0013] Step 6: Transfer the above colorless and transparent mixture to a reaction vessel, seal it, and place it in an oven for heat preservation to obtain crude amorphous tungsten oxide nanosheets;
[0014] Step 7: Product post-processing After the reactor has cooled to room temperature naturally, the crude product is taken out and subjected to separation, washing and drying processes in sequence to obtain pure amorphous tungsten oxide nanosheets.
[0015] Preferably, the tungsten source in step 1 is ammonium paratungstate, with an amount of 900 mg; the solvent used is deionized water; the stirring rate is controlled at 300~400 r / min; and the stirring time is 15~20 min to ensure that the tungsten salt is completely dissolved and to avoid uneven morphology of the subsequent product due to excessively high local concentration.
[0016] Preferably, the surfactant in step 2 is sodium dodecylbenzenesulfonate, with an amount of 1 g, which forms an optimal ratio (mass ratio of about 1:0.9) with 900 mg of ammonium paratungstate in step 1, so as to give full play to the dispersing effect; the solvent is also deionized water, the stirring speed is 300~400 r / min, and the stirring time is 10~15 min to ensure that the surfactant is completely dissolved and forms a uniform solution.
[0017] Preferably, the volume of solution A prepared in step 1 and solution B prepared in step 2 is 50 mL. This volume setting ensures that the system concentration after mixing the two solutions is moderate, avoiding particle agglomeration due to excessive concentration and reducing reaction efficiency due to excessively low concentration, while also being compatible with the loading capacity of conventional reaction vessels.
[0018] Preferably, in step 3, the pH of the solution is adjusted to 4; the preferred acid source is citric acid (concentration 0.5 mol / L), and the dropping rate is controlled at 1~2 drops / second, with stirring while adding to ensure a uniform and stable pH; the step heating rate is set to 2~3℃ / min, and the temperature is slowly increased to 70~80℃ (preferably 75℃), which can avoid the rapid hydrolysis of tungstate ions caused by a sudden temperature rise, and is conducive to the formation of amorphous structure.
[0019] Preferably, the macromolecular chain organic stabilizer in step 4 is polyacrylic acid with a molecular weight of 80,000, and its dosage is 15% of the mass of ammonium paratungstate (i.e., 135 mg). After the polyacrylic acid is prepared into a 5% aqueous solution, it is added. The ultrasonic power is set to 150~200 W, the ultrasonic temperature is preferably 30℃, and the ultrasonic time is 25~30 min. This allows the stabilizer to be uniformly adsorbed on the surface of the nanosheets, effectively improving the stability and dispersibility of the amorphous structure.
[0020] Preferably, the oven temperature setting in step 6 is 160°C and the holding time is 6 h. This condition can balance the completeness of the reaction and the stability of the amorphous phase, avoid the crystallization of the amorphous phase due to excessive temperature, and ensure that the precursor is fully converted into the target product.
[0021] Preferably, in the post-processing of the product in step 7, the separation method is centrifugation at a speed of 9000 r / min; the washing process is to first wash with deionized water 4 times, each time for 6 min, to remove soluble salt impurities, and then wash with anhydrous ethanol 4 times, each time for 5 min, to remove residual surfactants and organic impurities; the drying conditions are vacuum drying at 60℃ for 8 h, which can avoid high-temperature drying from damaging the amorphous structure and ensure that the product is thoroughly dried.
[0022] The beneficial effects of this invention are:
[0023] 1. This invention effectively overcomes the technical bottlenecks of irregular product morphology and high size distribution dispersion in existing processes by precisely controlling the material ratio, stepwise heating rate, and pH value of the reaction system. The prepared amorphous tungsten oxide nanosheets possess both regular morphological characteristics and uniform size distribution, providing a solid structural guarantee for the performance stability in their subsequent applications.
[0024] 2. This invention uses readily available and inexpensive chemical raw materials such as ammonium paratungstate and sodium dodecylbenzenesulfonate, eliminating the need for expensive reagents and significantly reducing raw material costs. The process parameters are mild, and key parameters in each step (such as stirring rate and reaction time) are compatible with conventional industrial production equipment. Furthermore, the solution volume setting matches the loading specifications of conventional reaction vessels. Compared to existing complex preparation processes, this method significantly reduces overall production costs and possesses excellent potential for large-scale mass production.
[0025] 3. The precisely designed post-processing technology can effectively remove soluble salts, residual surfactants, and organic impurities from the system, resulting in a product with high purity and no significant impurity residue. Furthermore, the amorphous structure endows the material with a high specific surface area and abundant active sites, making it suitable for applications in multiple fields such as photocatalysis, gas sensing, and electrochemical energy storage. Compared to existing tungsten oxide nanomaterials with limited functional targeting, the application adaptability of the product of this invention is significantly improved. Attached Figure Description
[0026] The present invention will be further described below with reference to the accompanying drawings and embodiments:
[0027] Figure 1 The photochromic behavior of the amorphous tungsten oxide nanosheet dispersion prepared in Example 1 is demonstrated: A represents the state without xenon lamp irradiation, where the dispersion is a uniform light gray semi-transparent state, reflecting the good dispersibility of the nanosheets in the solution; B represents the state after only 0.5 s of xenon lamp irradiation, where the dispersion rapidly turns into an opaque deep blue. This is because the amorphous structure of the amorphous tungsten oxide nanosheets contains abundant defect sites, which undergo rapid electron transfer under photoexcitation, drastically enhancing its absorption capacity for visible light, thus directly demonstrating the excellent photoresponsive activity of the material.
[0028] Figure 2 Transmission electron microscopy (TEM) images and selected area electron diffraction (SAED) patterns of the amorphous tungsten oxide nanosheets prepared in Example 1 are shown: The TEM image shows that the material exhibits a uniform nanosheet morphology with good dispersion and no obvious agglomeration at the 20 nm scale; the SAED pattern in the upper right corner shows a diffuse halo rather than clear crystalline diffraction spots, which is a typical amorphous structure feature, confirming the amorphous characteristics of the material.
[0029] Figure 3The high-resolution transmission electron microscope (HRTEM) image of the amorphous tungsten oxide nanosheets prepared in Example 1 shown in the image does not show the lattice fringes characteristic of crystalline materials, which further confirms its amorphous structure.
[0030] Figure 4 The scanning transmission electron microscope (STEM) images of the amorphous tungsten oxide nanosheets prepared in Example 1 and the distribution characteristics of tungsten (W) and oxygen (O) elements are shown: the STEM image on the left shows the nanosheet structure, and in the elemental distribution spectrum on the right, the distribution areas of tungsten (red) and oxygen (purple) elements highly overlap and are uniform overall, indicating that tungsten and oxygen elements are well uniformly dispersed in the nanosheets and no elemental agglomeration phenomenon occurs. Detailed Implementation
[0031] This section will describe in detail specific embodiments of the present invention. Preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the drawings is to supplement the textual description with graphics, so that people can intuitively and vividly understand each technical feature and overall technical solution of the present invention, but they should not be construed as limiting the scope of protection of the present invention.
[0032] Example 1
[0033] Step 1: Take 900 mg of ammonium paratungstate, add 50 mL of deionized water, and stir at 350 r / min for 18 min to obtain a homogeneous precursor solution A;
[0034] Step 2: Take 1 g of sodium dodecylbenzenesulfonate, add 50 mL of deionized water, and stir at 350 r / min for 12 min to obtain solution B;
[0035] Step 3: Stir solution B, add 0.5 mol / L citric acid at a rate of 1.5 drops / second to adjust the pH to 4, and simultaneously increase the temperature to 75℃ in steps at a rate of 2.5℃ / min; while maintaining the temperature and stirring, slowly add solution A dropwise to solution B, and keep the reaction at this temperature for 1 hour after the addition is complete.
[0036] Step 4: Take 135 mg of polyacrylic acid with a molecular weight of 80,000, prepare a 5% (w / w) aqueous solution, add it to the above solution and mix well; place it in an environment of 30°C and sonicate at 80 W power for 28 min.
[0037] Step 5: Heat the system to 80℃ and stir for 5 hours to obtain a colorless and transparent mixture;
[0038] Step 6: Transfer the mixture to a reaction vessel, seal it, and keep it in an oven at 160℃ for 6 hours to obtain the crude product;
[0039] Step 7: After the reactor is cooled to room temperature, the crude product is taken out and centrifuged at 9000 r / min; it is first washed 4 times with deionized water and then washed 4 times with anhydrous ethanol; finally, it is vacuum dried at 60℃ for 8 h to obtain amorphous tungsten oxide nanosheets.
[0040] Example 2
[0041] Step 1: Take 850 mg of sodium tungstate (which has the same tungsten content as 900 mg of ammonium paratungstate), add 50 mL of deionized water, and stir at 300 r / min for 20 min to obtain precursor solution A;
[0042] Step 2: Take 1 g of sodium dodecylbenzenesulfonate, add 50 mL of deionized water, and stir at 300 r / min for 15 min to obtain solution B;
[0043] Step 3: Stir solution B, add 0.5 mol / L citric acid dropwise at a rate of 1 drop / second to adjust the pH to 4, and simultaneously increase the temperature stepwise to 70℃ at a rate of 2℃ / min; while maintaining the temperature and stirring, slowly add solution A dropwise to solution B, and keep the reaction at this temperature for 1 h after the addition is complete.
[0044] Step 4: Take 127.5 mg of polyacrylic acid with a molecular weight of 80000 (15% of the mass of sodium tungstate), prepare a 5% (w / w) aqueous solution, add it to the above solution and mix well; place it in an environment of 25°C and sonicate at 150 W power for 30 min;
[0045] Step 5: Heat the system to 80℃ and stir for 5 hours to obtain a colorless and transparent mixture;
[0046] Step 6: Transfer the mixture to a reaction vessel, seal it, and keep it in an oven at 150°C for 7 hours to obtain the crude product;
[0047] Step 7: After the reactor is cooled to room temperature, the crude product is taken out and centrifuged at 9000 r / min; it is first washed 5 times with deionized water and then washed 4 times with anhydrous ethanol (5 min each time); finally, it is vacuum dried at 60℃ for 8 h to obtain amorphous tungsten oxide nanosheets.
[0048] Example 3
[0049] Step 1: Take 900 mg of ammonium paratungstate, add 50 mL of deionized water, and stir at 400 r / min for 15 min to obtain precursor solution A;
[0050] Step 2: Take 1.2 g of sodium oleate (to meet the dispersion requirements of ammonium paratungstate), add 50 mL of deionized water, and stir at 400 r / min for 10 min to obtain solution B;
[0051] Step 3: Stir solution B, adjust the pH to 5 by adding 0.5 mol / L citric acid at a rate of 2 drops / second, and simultaneously increase the temperature to 80℃ in steps at a rate of 3℃ / min; while maintaining the temperature and stirring, slowly add solution A dropwise to solution B, and keep the reaction at this temperature for 1 h after the addition is complete.
[0052] Step 4: Take 135 mg of polyacrylic acid with a molecular weight of 80,000, prepare a 5% (w / w) aqueous solution, add it to the above solution and mix well; place it in an environment of 40°C and sonicate it at 200 W power for 10 min.
[0053] Step 5: Heat the system to 80℃ and stir for 5 hours to obtain a colorless and transparent mixture;
[0054] Step 6: Transfer the mixture to a reaction vessel, seal it, and keep it in an oven at 180°C for 5 hours to obtain the crude product;
[0055] Step 7: After the reactor is cooled to room temperature, the crude product is taken out and centrifuged at 10,000 r / min; it is first washed 3 times with deionized water and then washed 5 times with anhydrous ethanol; finally, it is vacuum dried at 60℃ for 8 h to obtain pure amorphous tungsten oxide nanosheets.
Claims
1. A method for preparing amorphous tungsten oxide nanoplatelets, characterized in that, The method steps are as follows: Step 1: Dissolve tungsten salt in water and stir until dissolved to obtain precursor solution A; Step 2: Dissolve the surfactant in water and stir until it is completely dissolved to obtain solution B; Step 3: Stir solution B, adjust the pH of the solution, and simultaneously raise the temperature to 70~80℃ using a step-by-step heating method; while maintaining this temperature and stirring, slowly add precursor solution A dropwise to solution B, and continue the reaction for 1 h after the addition is complete; Step 4: Add an aqueous solution of macromolecular chain organic stabilizer to the pH-adjusted solution and mix thoroughly; place the mixture in an environment of 20~40℃ and sonicate for 10~40 min. Step 5: After ultrasonic treatment, heat the system to 80°C and continue stirring at this temperature for 5 hours to obtain a colorless and transparent mixture. Step 6: Transfer the above colorless and transparent mixture to a reaction vessel, seal it, and place it in an oven for heat preservation to obtain crude amorphous tungsten oxide nanosheets; Step 7: Product post-processing After the reactor has cooled to room temperature naturally, the crude product is taken out and subjected to separation, washing and drying processes in sequence to obtain pure amorphous tungsten oxide nanosheets.
2. The method for preparing amorphous tungsten oxide nanosheets according to claim 1, characterized in that: The tungsten source is one of ammonium paratungstate, sodium tungstate, or tungstic acid.
3. The method for preparing amorphous tungsten oxide nanosheets according to claim 1, characterized in that: The surfactant is one of sodium dodecylbenzenesulfonate, sodium dodecyl sulfate, and sodium oleate.
4. The method for preparing amorphous tungsten oxide nanosheets according to claim 1, characterized in that: The pH adjustment is 3-5.
5. The method for preparing amorphous tungsten oxide nanosheets according to claim 1, characterized in that: The macromolecular chain organic stabilizer is one of polyacrylic acid (molecular weight 10,000-100,000) and sodium polyacrylate (molecular weight 50,000-100,000).
6. The method for preparing amorphous tungsten oxide nanosheets according to claim 1, characterized in that: The oven is kept at 150℃~180℃, and the reaction time is 5 h-7 h.
7. The method for preparing amorphous tungsten oxide nanosheets according to claim 1, characterized in that: First, use deionized water as the washing solution and centrifuge at 8000~10000 r / min for 3~5 times, each centrifugation time is 5~8 min, to remove soluble salt impurities in the system; then use anhydrous ethanol as the washing solution and centrifuge at the same speed for 3~5 times, each centrifugation time is 5 min, to remove residual surfactants and organic impurities.