Dendritic tungsten oxide nano material, preparation method and NO2 gas detection application thereof

Abstract

The invention discloses a dendritic tungsten oxide nano material, a preparation method and NO2 gas detection application thereof, and the preparation method comprises the following steps: preparing the dendritic tungsten oxide nano material by using Pluronic F127 as a template agent and silicotungstic acid as an inorganic precursor through a solvent evaporation induced self-assembly method; the dendritic tungsten oxide nano material prepared by the method has high sensitivity to NO2 gas, and the preparation method is simple, relatively low in cost, safe and environment-friendly.

Description

Technical Field

[0001] The present invention belongs to the field of nano-semiconductor materials and relates to a dendritic tungsten oxide nano-material, a preparation method and NO2 gas detection application thereof. Background Art

[0002] Nitrogen dioxide (NO2) is a toxic and harmful gas primarily derived from the combustion of fossil fuels such as oil and coal. Excessive NO2 emissions not only severely damage the ecological environment but also pose serious risks to humans and other living things. Studies have shown that NO2 concentrations exceeding 3 ppm can irritate the lungs and damage the respiratory system. Therefore, the identification and detection of NO2 is extremely important.

[0003] Tungsten oxide (WO3) is a typical metal oxide semiconductor material with the advantages of being non-toxic, inexpensive, readily available raw materials, and having high electron mobility. Therefore, it has demonstrated excellent application performance in the field of NO2 gas detection. However, due to the small specific surface area of ​​bulk tungsten oxide and the few molecular adsorption sites, the response value to NO2 gas is low. Dendritic nanostructure is a three-dimensional ordered porous structure assembled from a trunk and multi-level branches. It has the advantages of a large specific surface area and abundant active sites, which are conducive to promoting gas diffusion and adsorption. In addition, due to the mutual contact between the trunk and the branches, the dendritic nanostructure also has good carrier transport channels and high charge transport efficiency, thereby significantly improving gas detection performance. Therefore, dendritic tungsten oxide nanomaterial is an ideal NO2 gas sensitive material.

[0004] Existing methods for preparing dendritic nanostructures primarily include photolithography, electrospinning, electrodeposition, and hydrothermal methods. Photolithography, through an etching process, can produce three-dimensional, ordered porous structures on substrate surfaces. Electrospinning, through the use of an electric field, can spray a spinning solution into dendritic nanofibers. Electrodeposition, through the application of an external electric field, can reduce metal ions and deposit them on an electrode surface, thereby forming a specific morphological structure. Hydrothermal methods, through seeded secondary hydrothermal growth, can construct dendritic nanostructures on substrate surfaces. However, these preparation methods typically require expensive laboratory instruments, complex procedures, and expensive consumables. They are associated with high production costs, high energy consumption, and demanding reaction conditions. Furthermore, the preparation process requires the use of toxic and hazardous reagents such as photoresist and tetrabutylammonium hexafluorophosphate, which can pose serious risks to the health of experimenters and the surrounding environment.

[0005] Based on this, the design and development of a dendritic tungsten oxide nanomaterial with simple process, low preparation cost, safety and environmental protection and high sensitivity to NO2 gas has important practical significance and application value. Summary of the Invention

[0006] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a dendritic tungsten oxide nanomaterial, a preparation method and its NO2 gas detection application. The dendritic tungsten oxide nanomaterial prepared by this method has high sensitivity to NO2 gas, and the preparation method is simple, low cost, safe and environmentally friendly.

[0007] To achieve the above object, the present invention discloses a method for preparing a dendritic tungsten oxide nanomaterial, comprising the following steps:

[0008] Dendritic tungsten oxide nanomaterials were prepared by solvent evaporation-induced self-assembly method using Pluronic F127 as template and silicotungstic acid as inorganic precursor.

[0009] Furthermore, the solvent is a mixture of ethanol and deionized water.

[0010] Furthermore, the method specifically includes the following steps:

[0011] 1) preparing a silicotungstic acid precursor solution;

[0012] 2) preparing a template Pluronic F127 solution;

[0013] 3) preparing a silicotungstic acid-Pluronic F127 composite film by using a silicotungstic acid precursor solution and a template agent Pluronic F127 solution;

[0014] 4) The silicotungstic acid-Pluronic F127 composite film obtained in step 3) is calcined under a nitrogen atmosphere, then naturally cooled, then calcined under an air atmosphere, and then naturally cooled to room temperature to obtain a dendritic tungsten oxide nanomaterial.

[0015] Furthermore, the process of step 1) is:

[0016] Silicotungstic acid hydrate is added to a mixed solution of ethanol and water, and then fully stirred to obtain a silicotungstic acid precursor solution, wherein the concentration of silicotungstic acid hydrate in the silicotungstic acid precursor solution is 3-8wt%.

[0017] Furthermore, the process of step 2) is:

[0018] Pluronic F127 is added to a mixed solution of ethanol and water, and then fully stirred to obtain a Pluronic F127 solution, wherein the concentration of Pluronic F127 in the Pluronic F127 solution is 3-8 wt %.

[0019] Furthermore, the process of step 3) is:

[0020] The silicotungstic acid precursor solution was added to the Pluronic F127 solution and stirred thoroughly to obtain a uniform mixed solution. The mixed solution was transferred to a culture dish, and the culture dish was placed on a heating table to allow the solution to evaporate slowly. After the solution evaporated completely, a silicotungstic acid-Pluronic F127 composite film was obtained.

[0021] Furthermore, the process of step 4) is:

[0022] The silicotungstic acid-Pluronic F127 composite film was transferred to a tube furnace and calcined at 400-500°C for 1-3 hours under a nitrogen atmosphere, and then naturally cooled. Then, it was calcined at 400-500°C for 1-3 hours under an air atmosphere, and then naturally cooled to room temperature to obtain a dendritic tungsten oxide nanomaterial.

[0023] The invention discloses a dendritic tungsten oxide nanomaterial, which is prepared based on the preparation method of the dendritic tungsten oxide nanomaterial.

[0024] Furthermore, the trunk diameter of the dendritic tungsten oxide nanomaterial is in the range of 350nm-370nm, the trunk length is in the range of 40μm-56μm, and the branch diameter is in the range of 90nm-110nm.

[0025] The invention discloses an application of a dendritic tungsten oxide nanomaterial in the field of NO2 gas detection.

[0026] The present invention has the following beneficial effects:

[0027] The dendritic tungsten oxide nanomaterial, preparation method and NO2 gas detection application of the present invention are specifically used in the operation of the amphiphilic block copolymer polyethylene oxide-polypropylene oxide-polyethylene oxide (PEO 106 -PPO 70 -PEO 106 The method uses Pluronic F127 (trade name Pluronic F127) as a template, ethanol and deionized water as solvents, and silicotungstic acid as an inorganic precursor to obtain an organic-inorganic composite nanostructure through solvent evaporation-induced self-assembly. Subsequently, dendritic tungsten oxide nanomaterials are obtained through curing and calcination. The raw materials required for this method are inexpensive, and the raw materials such as the template Pluronic F127, the inorganic precursor silicotungstic acid, and the solvent ethanol are extremely low in toxicity. The preparation method is simple, easy, low-cost, and environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings, which constitute part of the present invention, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0029] Figure 1a This is a scanning electron microscope image of the sample obtained in Example 1;

[0030] Figure 1b This is a scanning electron microscope image of the sample obtained in Example 2;

[0031] Figure 1c This is a scanning electron microscope image of the sample obtained in Example 3;

[0032] Figure 2 The XRD patterns of the samples obtained in Example 1, Example 2 and Example 3 are shown;

[0033] Figure 3 Response diagram of the sample obtained in Example 1 to 50 ppm NO2 gas at different temperatures;

[0034] Figure 4 This is a response curve of the sample obtained in Example 1 to 1-100 ppm NO2 gas at 250°C;

[0035] Figure 5 This is a response-recovery curve of the sample obtained in Example 1 to 50 ppm NO2 gas at 250°C;

[0036] Figure 6 Schematic diagram of the response values ​​of the samples obtained in Example 1, Example 2 and Example 3 to 50 ppm NO2 gas at 250°C. DETAILED DESCRIPTION

[0037] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0038] In the description of the present invention, it is to be understood that the terms “include” and “comprise” indicate the presence of the described features, wholes, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or collections thereof.

[0039] It should also be understood that the terms used in the present specification are only for the purpose of describing particular embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms unless the context clearly indicates otherwise.

[0040] It should be further understood that the term "and / or" as used in the present specification and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items. For example, A and / or B may represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in the present invention generally indicates that the associated objects are in an "or" relationship.

[0041] It should be understood that although the terms "first," "second," and "third" may be used to describe preset ranges in embodiments of the present invention, these preset ranges should not be limited to these terms. These terms are merely used to distinguish one preset range from another. For example, without departing from the scope of embodiments of the present invention, the first preset range may also be referred to as the second preset range, and similarly, the second preset range may also be referred to as the first preset range.

[0042] The word "if," as used herein, may be interpreted as "at the time of" or "when" or "in response to determining" or "in response to detecting," depending on the context. Similarly, the phrases "if it is determined" or "if (stated condition or event) is detected" may be interpreted as "when it is determined" or "in response to the determination" or "when detecting (stated condition or event)" or "in response to detecting (stated condition or event)," depending on the context.

[0043] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0044] The accompanying drawings illustrate various schematic diagrams of structures according to embodiments disclosed herein. These figures are not drawn to scale; for clarity, some details are exaggerated and some details may be omitted. The shapes of the various regions and layers shown in the figures, as well as their relative sizes and positional relationships, are merely exemplary and may deviate in practice due to manufacturing tolerances or technical limitations. Those skilled in the art may design regions / layers with different shapes, sizes, and relative positions as needed.

[0045] The preparation method of the dendritic tungsten oxide nanomaterial of the present invention comprises the following steps:

[0046] Dendritic tungsten oxide nanomaterials were prepared by solvent evaporation-induced self-assembly method using Pluronic F127 as template, ethanol and deionized water as solvents and silicotungstic acid as inorganic precursor.

[0047] The PEO in the Pluronic F127 molecule is a hydrophilic group, while the PPO is a hydrophobic group. In a polar mixed solution of ethanol and deionized water, the hydrophobic PPO groups aggregate inward, while the hydrophilic PEO groups spread outward. Under electrostatic forces, silicotungstate ions can adsorb on the surface of the hydrophilic PEO groups, forming core-shell spherical micelles with Pluronic F127 as the core and silicotungstate ions as the shell. Subsequently, the solvent is gradually evaporated, inducing the spherical micelles to fuse into columnar micelles. Finally, a calcination treatment removes the template Pluronic F127 and simultaneously crystallizes WO3, resulting in a dendritic tungsten oxide nanomaterial. The dendritic tungsten oxide nanomaterial has a trunk diameter ranging from 350nm to 370nm, a trunk length ranging from 40μm to 56μm, and a branch diameter ranging from 90nm to 110nm.

[0048] The preparation method of the dendritic tungsten oxide nanomaterial specifically comprises the following steps:

[0049] 1) preparing a silicotungstic acid precursor solution;

[0050] Silicate tungstic acid hydrate (H4SiW 12 O 40 ·xH2O) is added to a mixed solution of ethanol and water with a volume ratio of 2:1, and then stirred at a stirring speed of 400 rpm / s for 30 minutes to obtain a silicotungstic acid precursor solution, wherein the concentration of silicotungstic acid hydrate in the silicotungstic acid precursor solution is 3 to 8 wt%.

[0051] 2) preparing a template Pluronic F127 solution;

[0052] Pluronic F127 was added to a mixture of ethanol and water in a volume ratio of 2:1, and the mixture was stirred at 400 rpm / s for 30 minutes to obtain a Pluronic F127 solution having a concentration of 3 to 8 wt %.

[0053] 3) Preparation of silicotungstic acid-Pluronic F127 composite film;

[0054] The silicotungstic acid precursor solution obtained in step 1) was added to the Pluronic F127 solution obtained in step 2), and the mixture was stirred at a stirring speed of 400 rpm / s for 60 minutes to obtain a uniform mixed solution. The mixed solution was transferred to a culture dish, and the culture dish was placed on a heating table at 45°C to allow the solution to slowly evaporate for 24 hours. After the solution evaporated completely, a silicotungstic acid-Pluronic F127 composite film was obtained.

[0055] 4) Preparation of dendritic tungsten oxide nanomaterials;

[0056] The silicotungstic acid-Pluronic F127 composite film obtained in step 3) is transferred to a tube furnace and calcined at 400-500°C for 1-3 hours under a nitrogen atmosphere at a heating rate of 1-2°C / min. After calcination, it is naturally cooled for 5 hours, and then calcined at 400-500°C for 1-3 hours under an air atmosphere at a heating rate of 1-2°C / min. After calcination, it is naturally cooled to room temperature to obtain a dendritic tungsten oxide nanomaterial.

[0057] The dendritic tungsten oxide nanomaterial provided by the present invention has a trunk and multi-level branches that are interconnected to form a three-dimensional ordered porous structure, which is beneficial to promoting gas diffusion and adsorption and improving carrier transport efficiency.

[0058] In the preparation method provided by the present invention, the raw materials Pluronic F127, silicotungstic acid, and the solvent ethanol are all mature commodities, easily available, and inexpensive. Compared with the prior art, the present invention does not require expensive experimental equipment, has fewer experimental steps, reduces preparation costs, and provides a simpler preparation process. Furthermore, no toxic or hazardous reagents are used in the preparation process, effectively avoiding the health and environmental risks that may arise from such reagents, making the experiment safer and more environmentally friendly.

[0059] The dendritic tungsten oxide nanomaterial prepared by this invention exhibits excellent NO2 gas detection performance. Due to its large specific surface area, abundant active sites, and excellent carrier transport pathways, the dendritic tungsten oxide nanomaterial exhibits high sensitivity to NO2 gas. At the optimal operating temperature of 250°C, the dendritic tungsten oxide nanomaterial exhibits a response value of 122.2 to 50 ppm NO2 gas, with response and recovery times of 32 seconds and 193 seconds, respectively.

[0060] Example 1

[0061] The preparation method of the dendritic tungsten oxide nanomaterial of the present invention comprises the following steps:

[0062] 1) Add 0.079 g of silicotungstic acid to a mixed solution of 2 mL of ethanol and 1 mL of water, and then stir the mixture at a stirring speed of 400 rpm / s for 30 minutes to obtain a silicotungstic acid precursor solution.

[0063] 2) 0.079 g of Pluronic F127 was added to a mixed solution of 2 mL of ethanol and 1 mL of water, and the mixture was stirred at 400 rpm / s for 30 min to obtain a Pluronic F127 precursor solution.

[0064] 3) 3 mL of the silicotungstic acid precursor solution in step 1) was added to 3 mL of the Pluronic F127 solution in step 2), and the mixture was stirred at 400 rpm / s for 60 minutes to obtain a uniform mixed solution. The mixed solution was then transferred to a culture dish and placed on a heating plate at 45°C to allow the solution to evaporate slowly for 24 hours to form a silicotungstic acid-Pluronic F127 composite film.

[0065] 4) The silicotungstic acid-Pluronic F127 composite film was transferred to a tube furnace and calcined at 400°C for 2 h in a nitrogen atmosphere at a heating rate of 1°C / min. After calcination, the film was naturally cooled for 5 h. Subsequently, the film was calcined at 400°C for 2 h in an air atmosphere at a heating rate of 1°C / min. After calcination, the film was naturally cooled to room temperature to obtain a dendritic tungsten oxide nanomaterial.

[0066] Example 2

[0067] The preparation method of the dendritic tungsten oxide nanomaterial of the present invention comprises the following steps:

[0068] 1) Add 0.149 g of silicotungstic acid to a mixed solution of 2 mL of ethanol and 1 mL of water, and then stir the mixture at a stirring speed of 400 rpm / s for 30 minutes to obtain a silicotungstic acid precursor solution.

[0069] 2) 0.149 g of Pluronic F127 was added to a mixed solution of 2 mL of ethanol and 1 mL of water, and the mixture was stirred at 400 rpm / s for 30 min to obtain a Pluronic F127 precursor solution.

[0070] 3) 3 mL of the silicotungstic acid precursor solution in step 1) was added to 3 mL of the Pluronic F127 solution in step 2), and the mixture was stirred at 400 rpm / s for 60 minutes to obtain a uniform mixed solution. Subsequently, the mixed solution was transferred to a culture dish, and the culture dish was placed on a heating table at 45° C. The solution was slowly evaporated for 24 hours to form a silicotungstic acid-Pluronic F127 composite film.

[0071] 4) The silicotungstic acid-Pluronic F127 composite film was transferred to a tube furnace and calcined at 400°C for 2 h under a nitrogen atmosphere at a heating rate of 1°C / min. After calcination, the film was naturally cooled for 5 h. Subsequently, the film was calcined at 400°C for 2 h under an air atmosphere at a heating rate of 1°C / min. After calcination, the film was naturally cooled to room temperature to obtain a dendritic tungsten oxide nanomaterial.

[0072] Example 3

[0073] The preparation method of the dendritic tungsten oxide nanomaterial of the present invention comprises the following steps:

[0074] 1) Add 0.223 g of silicotungstic acid to a mixed solution of 2 mL of ethanol and 1 mL of water, and stir thoroughly at 400 rpm / s for 30 minutes to obtain a silicotungstic acid precursor solution;

[0075] 2) 0.223 g of Pluronic F127 was added to a mixed solution of 2 mL of ethanol and 1 mL of water, and the mixture was stirred at 400 rpm / s for 30 min to obtain a Pluronic F127 precursor solution.

[0076] 3) 3 mL of the silicotungstic acid precursor solution in step 1) was added to 3 mL of the Pluronic F127 solution in step 2), and the mixture was stirred at 400 rpm / s for 60 minutes to obtain a uniform mixed solution. Subsequently, the mixed solution was transferred to a culture dish, and the culture dish was placed on a heating table at 45° C. The solution was slowly evaporated for 24 hours to form a silicotungstic acid-Pluronic F127 composite film.

[0077] 4) The silicotungstic acid-Pluronic F127 composite film was transferred to a tube furnace and calcined at 400°C for 2 h under a nitrogen atmosphere at a heating rate of 1°C / min. After calcination, the film was naturally cooled for 5 h. Subsequently, the film was calcined at 400°C for 2 h under an air atmosphere at a heating rate of 1°C / min. After calcination, the film was naturally cooled to room temperature to obtain a dendritic tungsten oxide nanomaterial.

[0078] Example 4

[0079] The preparation method of the dendritic tungsten oxide nanomaterial specifically comprises the following steps:

[0080] 1) preparing a silicotungstic acid precursor solution;

[0081] Silicate tungstic acid hydrate (H4SiW 12 O 40·xH2O) was added to a mixed solution of ethanol and water in a volume ratio of 2:1, and then stirred at a stirring speed of 400 rpm / s for 30 minutes to obtain a silicotungstic acid precursor solution, wherein the concentration of silicotungstic acid hydrate in the silicotungstic acid precursor solution was 6wt%.

[0082] 2) preparing a template Pluronic F127 solution;

[0083] Pluronic F127 was added to a mixture of ethanol and water in a volume ratio of 2:1, and the mixture was stirred at 400 rpm / s for 30 minutes to obtain a Pluronic F127 solution having a concentration of 6 wt %.

[0084] 3) Preparation of silicotungstic acid-Pluronic F127 composite film;

[0085] The silicotungstic acid precursor solution obtained in step 1) was added to the Pluronic F127 solution obtained in step 2), and the mixture was stirred at a stirring speed of 400 rpm / s for 60 minutes to obtain a uniform mixed solution. The mixed solution was transferred to a culture dish, and the culture dish was placed on a heating table at 45°C to allow the solution to slowly evaporate for 24 hours. After the solution evaporated completely, a silicotungstic acid-Pluronic F127 composite film was obtained.

[0086] 4) Preparation of dendritic tungsten oxide nanomaterials;

[0087] The silicotungstic acid-Pluronic F127 composite film obtained in step 3) was transferred to a tube furnace and calcined at 450°C for 2 hours under a nitrogen atmosphere at a heating rate of 1.5°C / min. After the calcination, it was naturally cooled for 5 hours. Then, it was calcined at 450°C for 2 hours under an air atmosphere at a heating rate of 1.5°C / min. After the calcination, it was naturally cooled to room temperature to obtain a dendritic tungsten oxide nanomaterial.

[0088] Example 5

[0089] The preparation method of the dendritic tungsten oxide nanomaterial specifically comprises the following steps:

[0090] 1) preparing a silicotungstic acid precursor solution;

[0091] Silicate tungstic acid hydrate (H4SiW 12 O 40·xH2O) was added to a mixed solution of ethanol and water with a volume ratio of 2:1, and then stirred at a stirring speed of 400 rpm / s for 30 minutes to obtain a silicotungstic acid precursor solution, wherein the concentration of silicotungstic acid hydrate in the silicotungstic acid precursor solution was 8wt%.

[0092] 2) preparing a template Pluronic F127 solution;

[0093] Pluronic F127 was added to a mixture of ethanol and water in a volume ratio of 2:1, and the mixture was stirred at 400 rpm / s for 30 minutes to obtain a Pluronic F127 solution having a concentration of 8 wt %.

[0094] 3) Preparation of silicotungstic acid-Pluronic F127 composite film;

[0095] The silicotungstic acid precursor solution obtained in step 1) was added to the Pluronic F127 solution obtained in step 2), and the mixture was stirred at a stirring speed of 400 rpm / s for 60 minutes to obtain a uniform mixed solution. The mixed solution was transferred to a culture dish, and the culture dish was placed on a heating table at 45°C to allow the solution to slowly evaporate for 24 hours. After the solution evaporated completely, a silicotungstic acid-Pluronic F127 composite film was obtained.

[0096] 4) Preparation of dendritic tungsten oxide nanomaterials;

[0097] The silicotungstic acid-Pluronic F127 composite film obtained in step 3) was transferred to a tube furnace and calcined at 500°C for 3 hours under a nitrogen atmosphere at a heating rate of 2°C / min. After the calcination, it was naturally cooled for 5 hours, and then calcined at 500°C for 3 hours under an air atmosphere at a heating rate of 2°C / min. After the calcination, it was naturally cooled to room temperature to obtain a dendritic tungsten oxide nanomaterial.

[0098] Example 6

[0099] The preparation method of the dendritic tungsten oxide nanomaterial specifically comprises the following steps:

[0100] 1) preparing a silicotungstic acid precursor solution;

[0101] Silicate tungstic acid hydrate (H4SiW 12 O 40 ·xH2O) was added to a mixed solution of ethanol and water in a volume ratio of 2:1, and then stirred at a stirring speed of 400 rpm / s for 30 minutes to obtain a silicotungstic acid precursor solution, wherein the concentration of silicotungstic acid hydrate in the silicotungstic acid precursor solution was 3wt%.

[0102] 2) preparing a template Pluronic F127 solution;

[0103] Pluronic F127 was added to a mixture of ethanol and water in a volume ratio of 2:1, and the mixture was stirred at 400 rpm / s for 30 minutes to obtain a Pluronic F127 solution having a concentration of 3 wt %.

[0104] 3) Preparation of silicotungstic acid-Pluronic F127 composite film;

[0105] The silicotungstic acid precursor solution obtained in step 1) was added to the Pluronic F127 solution obtained in step 2), and the mixture was stirred at a stirring speed of 400 rpm / s for 60 minutes to obtain a uniform mixed solution. The mixed solution was transferred to a culture dish, and the culture dish was placed on a heating table at 45°C to allow the solution to slowly evaporate for 24 hours. After the solution evaporated completely, a silicotungstic acid-Pluronic F127 composite film was obtained.

[0106] 4) Preparation of dendritic tungsten oxide nanomaterials;

[0107] The silicotungstic acid-Pluronic F127 composite film obtained in step 3) was transferred to a tube furnace and calcined at 400°C for 1 hour under a nitrogen atmosphere at a heating rate of 1°C / min. After the calcination, it was naturally cooled for 5 hours, and then calcined at 400°C for 1 hour under an air atmosphere at a heating rate of 1°C / min. After the calcination, it was naturally cooled to room temperature to obtain a dendritic tungsten oxide nanomaterial.

[0108] Figure 1a 、 Figure 1b and Figure 1c The following are scanning electron microscope images of the samples obtained in Example 1, Example 2, and Example 3, respectively. As can be seen from the figure, the morphology of tungsten oxide is a typical dendritic structure, with the trunk and branches closely connected, and multiple branches parallel to each other. Among them, the trunk diameter of the sample obtained in Example 1 is about 350nm, the trunk length is about 40μm, and the branch diameter is about 90nm; the trunk diameter of the sample obtained in Example 2 is about 360nm, the trunk length is about 46μm, and the branch diameter is about 100nm; the trunk diameter of the sample obtained in Example 3 is about 370nm, the trunk length is about 56μm, and the branch diameter is about 110nm.

[0109] Figure 220-1324) and have no impurity peaks, indicating that the samples have the same crystal structure.

[0110] Figure 3 The response values ​​of the sample obtained in Example 1 to 50 ppm NO2 gas at different temperatures are shown in the figure. As can be seen from the figure, as the operating temperature increases, the sample's response value to NO2 gas increases first and then decreases. When the operating temperature is 250°C, the sample's response value to 50 ppm NO2 gas is the highest, with a value of 122.2.

[0111] Figure 4 The sample obtained in Example 1 shows the response to NO₂ gas concentrations of 1 to 100 ppm at 250°C. As the NO₂ concentration gradually increases from 1 ppm to 100 ppm, the sample's response increases significantly, and the response shows a good linear relationship with the NO₂ concentration. At 100 ppm, the sample's response reaches 230.3.

[0112] Figure 5 This is the dynamic response-recovery curve of the sample obtained in Example 1 to 50 ppm NO2 gas at 250°C. As can be seen from the figure, the recovery and response time of the sample in detecting NO2 gas are 32s and 193s respectively.

[0113] Figure 6 The responses of the samples obtained in Examples 1, 2, and 3 to 50 ppm NO₂ gas at 250°C are shown. As can be seen from the figure, all three samples exhibit high sensitivity to NO₂ gas. The responses of the samples obtained in Examples 1, 2, and 3 to 50 ppm NO₂ gas are 122.2, 113.5, and 102.3, respectively.

[0114] Those skilled in the art will readily identify other embodiments of the present invention after considering the specification and disclosure of the invention. This application is intended to cover any variations, uses, or adaptations of the present invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. The description and examples are to be considered as exemplary only, with the true scope and spirit of the invention being indicated by the following claims.

[0115] It should be understood that the present invention is not limited to the exact construction described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

[0116] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent structural change made to the above embodiment based on the technical essence of the present invention shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for preparing a dendritic tungsten oxide nanomaterial, characterized in that: The following steps are involved: Dendritic tungsten oxide nanomaterials were prepared by solvent evaporation-induced self-assembly method using Pluronic F127 as template and silicotungstic acid as inorganic precursor.

2. The method for preparing the dendritic tungsten oxide nanomaterial according to claim 1, characterized in that: The solvent is a mixture of ethanol and deionized water.

3. The method for preparing the dendritic tungsten oxide nanomaterial according to claim 1, characterized in that: The specific steps include: 1) preparing a silicotungstic acid precursor solution; 2) preparing a template Pluronic F127 solution; 3) preparing a silicotungstic acid-Pluronic F127 composite film using a silicotungstic acid precursor solution and a template agent Pluronic F127 solution; 4) The silicotungstic acid-Pluronic F127 composite film obtained in step 3) is calcined under a nitrogen atmosphere, then naturally cooled, then calcined under an air atmosphere, and then naturally cooled to room temperature to obtain a dendritic tungsten oxide nanomaterial.

4. The method for preparing the dendritic tungsten oxide nanomaterial according to claim 3, characterized in that: The process of step 1) is: Silicotungstic acid hydrate is added to a mixed solution of ethanol and water, and then fully stirred to obtain a silicotungstic acid precursor solution, wherein the concentration of silicotungstic acid hydrate in the silicotungstic acid precursor solution is 3-8wt%.

5. The method for preparing the dendritic tungsten oxide nanomaterial according to claim 3, characterized in that: The process of step 2) is: Pluronic F127 is added to a mixed solution of ethanol and water, and then fully stirred to obtain a Pluronic F127 solution, wherein the concentration of Pluronic F127 in the Pluronic F127 solution is 3-8 wt %.

6. The method for preparing the dendritic tungsten oxide nanomaterial according to claim 3, characterized in that: The process of step 3) is: The silicotungstic acid precursor solution was added to the Pluronic F127 solution and stirred thoroughly to obtain a uniform mixed solution. The mixed solution was transferred to a culture dish, and the culture dish was placed on a heating table to allow the solution to evaporate slowly. After the solution evaporated completely, a silicotungstic acid-Pluronic F127 composite film was obtained.

7. The method for preparing a dendritic tungsten oxide nanomaterial according to claim 3, characterized in that: The process of step 4) is: The silicotungstic acid-Pluronic F127 composite film was transferred to a tube furnace and calcined at 400-500°C for 1-3 hours under a nitrogen atmosphere, and then naturally cooled. Then, it was calcined at 400-500°C for 1-3 hours under an air atmosphere, and then naturally cooled to room temperature to obtain a dendritic tungsten oxide nanomaterial.

8. A dendritic tungsten oxide nanomaterial, characterized in that: The material is prepared based on the preparation method of the dendritic tungsten oxide nanomaterial according to any one of claims 1 to 7.

9. The dendritic tungsten oxide nanomaterial according to claim 8, characterized in that: The trunk diameter of the dendritic tungsten oxide nanomaterial is in the range of 350nm-370nm, the trunk length is in the range of 40μm-56μm, and the branch diameter is in the range of 90nm-110nm.

10. Use of the dendritic tungsten oxide nanomaterial according to claim 8 in the field of NO2 gas detection.

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