Porous V2O5 nanowire material prepared based on template-assisted hydrothermal method as well as preparation and application of porous V2O5 nanowire material

Abstract

The invention relates to a porous V2O5 nanowire material prepared based on a template-assisted hydrothermal method and preparation and application thereof.The nanowire material is prepared through the following steps that S1, in a nitrogen protection environment, NH4VO3 is weighed and added into a template agent aqueous solution, and an orange-yellow transparent solution is obtained; s2, dropwise adding a hydrochloric acid solution into the orange-yellow transparent solution obtained in the step S1, so that the solution is gradually converted into bright red colloid, and maintaining the pH value of the system in a range of 2.5-3.0; and S3, transferring the mixed solution obtained in the step S2 into a high-pressure reaction kettle, heating, carrying out a hydrothermal reaction, then cooling, separating, washing, dehydrating, and carrying out thermal annealing treatment in an air atmosphere to obtain the V2O5 nanowire. Compared with the prior art, the nanowire material provided by the invention can provide abundant chemical adsorption sites for NO2 molecules during application, the response and recovery time of a device is remarkably prolonged, meanwhile, the working temperature required by a sensor is relatively low, and the problems of high energy consumption, sensing material sintering and the like caused by high temperature are avoided.

Description

Technical Field

[0001] This invention belongs to the field of online monitoring and fault diagnosis technology for high-voltage electrical equipment, and relates to a porous V2O5 nanowire material prepared by template-assisted hydrothermal method and its preparation and application. Background Technology

[0002] Sulfur hexafluoride (SF6), widely used as an insulating medium in high-voltage switchgear and gas-insulated substations (GIS), is a key material in the power industry due to its superior dielectric strength (approximately three times that of air) and arc-quenching properties. However, according to the United Nations Framework Convention on Climate Change (UNFCCC) report, SF6 has a global warming potential (GWP). 100 =23,500 tons of SF6, far exceeding CO2 emissions, a single 550kV GIS device requires approximately 1.2 tons of SF6, and its leakage would cause a greenhouse effect equivalent to 28,200 tons of CO2 emissions. More seriously, SF6 has an atmospheric lifetime of over 3,200 years, posing a significant challenge to achieving the "dual-carbon" strategic goals. Therefore, the International Electrotechnical Commission (IEC) explicitly proposed the technical route of "reducing SF6 usage and exploring environmentally friendly alternative gases" in standard IEC 62271-203:2021.

[0003] Against this backdrop, breakthroughs have been achieved in the application research of nitrogen (N2) as an auxiliary insulating medium. Although N2, as a diatomic molecule, has a lower electron affinity (-1.9 eV) than SF6 (-3.5 eV), its insulation performance can be significantly improved by optimizing the mixing ratio. At a pressure of 0.4 MPa, the power frequency breakdown field strength of a 30% SF6 / 70% N2 mixture is 82% of that of pure SF6, while the amount of SF6 used is reduced by up to 70%. Furthermore, the molecular path of freedom of N2 (approximately 68 nm) is complementary to that of SF6 (approximately 43 nm), effectively suppressing the rate of partial discharge development.

[0004] However, in engineering applications, SF6 / N2 mixed gas systems face new challenges: during equipment operation, when the local electric field strength exceeds 30 kV / mm or there is a trace amount of H2O greater than 0.1%, SF6 / N2 will undergo a chain decomposition reaction in the discharge region.

[0005] SF6+e - →SF5-+F

[0006] N2+e - →2N-

[0007] F+N-→NF→NO2

[0008] The generated byproduct NO2 can act as an electron adsorbent, reducing the recovery strength of gas insulation, or combine with residual H2O to form an acidic HNO3 environment, accelerating the aging of sealing materials, leading to malfunctions in high-voltage electrical equipment, and even threatening the safe and stable operation of the power system. Therefore, it is essential to develop suitable gas sensors to monitor its presence.

[0009] Among various sensing technologies, resistive gas sensors have become the preferred solution for detecting decomposition products due to their advantages such as compact structure, rapid response, and low manufacturing cost. However, existing research mainly focuses on the detection of pure SF6 decomposition components, with insufficient development of sensitive materials for NO2 in mixed gases. Furthermore, they generally suffer from problems such as excessively high operating temperatures (>200℃) or the need for auxiliary excitation (ultraviolet light), making it difficult to meet the low-energy consumption monitoring requirements of modern power equipment. Summary of the Invention

[0010] The purpose of this invention is to provide a porous V2O5 nanowire material prepared by template-assisted hydrothermal method, and its preparation and application. When used for the detection of SF6 / N2 gas decomposition components, it can provide abundant chemical adsorption sites for NO2 molecules, significantly improving the response and recovery time of the device. At the same time, the sensor requires a low operating temperature, avoiding high energy consumption and sintering problems of sensing materials caused by high temperature.

[0011] The objective of this invention can be achieved through the following technical solutions:

[0012] In one aspect, the present invention provides a method for preparing porous V2O5 nanowire materials based on a template-assisted hydrothermal method, comprising the following steps:

[0013] S1. Under nitrogen protection, NH4VO3 was weighed and added to the template agent aqueous solution to obtain an orange-yellow transparent solution.

[0014] S2. Add hydrochloric acid solution dropwise to the orange-yellow transparent solution obtained in S1, so that the solution gradually turns into a bright red colloid, and maintain the pH value of the system in the range of 2.5-3.0;

[0015] S3. The mixed solution obtained in S2 is transferred to a high-pressure reactor, heated to react, then cooled, separated, and washed. The resulting precipitate is dehydrated and then heat-annealed in air to obtain V2O5 nanowires, which is the target product.

[0016] Furthermore, in S1, the template agent is Pluronic P123. Here, the molecular weight of Pluronic P123 is ~5800 g / mol, and Pluronic P123 dissolves in water to form EO. 20 PO 70 EO 20 The three-block structure is a hexagonal mesoporous phase.

[0017] Furthermore, in S1, the ratio of NH4VO3 to the template agent aqueous solution is (9-11) mmol:(55-65) mL, preferably 10 mmol:60 mL, and the concentration of the template agent aqueous solution is 4-6 wt%, preferably 5 wt%.

[0018] Furthermore, in step S2, the concentration of the hydrochloric acid solution is 0.8–1.2 M, preferably 1.0 M. During pH maintenance in step S2, if the pH exceeds this range, NH4VO3 or HCl needs to be added for adjustment.

[0019] Furthermore, in S3, the hydrothermal reaction process is as follows: first, the temperature is raised from room temperature to 100℃ (the heating rate can be 1-3℃ / min, etc.), and held at that temperature for 1 hour; then, the temperature is raised to 210-230℃ (the heating rate can be 1-3℃ / min, etc.), preferably 220℃, and held at that temperature for 20-28 hours, preferably 24 hours, while maintaining the pressure stable at 3.5-4.2 MPa.

[0020] Furthermore, in S3, the hot annealing process is as follows:

[0021] First, raise the temperature from room temperature to 300℃ (the heating rate can be 1-3℃ / min, etc.) and hold it at that temperature for 0.5-1.5h, preferably 1h. Then, continue to raise the temperature to 490-510℃ (the heating rate can be 3-5℃ / min), preferably 500℃, and hold it at that temperature for 1.5-2.5h, preferably 2h.

[0022] Furthermore, in S3, the washing process is as follows: wash three times each with anhydrous ethanol and deionized water.

[0023] Furthermore, in S3, the dehydration process is as follows: the precipitate is dehydrated in a vacuum drying oven at 60±2℃ for 24 hours.

[0024] In a second aspect, the present invention provides a porous V2O5 nanowire material prepared by a template-assisted hydrothermal method, which is prepared by the preparation method described in the first aspect above. The porous V2O5 nanowire material has a hierarchical porous structure with uniformly distributed pores.

[0025] In a third aspect, the present invention also provides the application of porous V2O5 nanowire materials prepared by template-assisted hydrothermal method as described in the second aspect above as gas-sensitive materials for detecting decomposition components of SF6 / N2 gas.

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] (1) The V2O5 nanowires prepared by the spatial confinement effect of Pluronic P123 template agent and the synergistic effect of hydrochloric acid intercalation have a hierarchical porous structure. Compared with the traditional sol-gel method, it can provide abundant chemical adsorption sites for NO2 molecules, significantly improve the response and recovery time of the device, and the sensor requires a lower operating temperature, avoiding high energy consumption and sintering problems of sensing materials caused by high temperature.

[0028] (2) The porous V2O5 nanowire material prepared by template-assisted hydrothermal method proposed in this invention has environmental protection throughout its entire life cycle. The preparation process adopts hydrothermal method, with no toxic by-products. Waste V2O5 nanowires can be regenerated by leaching with 0.5M NaOH solution, and the metal recovery rate is high.

[0029] (3) The porous V2O5 nanowire material prepared by template-assisted hydrothermal method proposed in this invention can be further extended to the preparation of other similar gas-sensitive materials, enriching the application of metal oxide nanowire materials in the field of gas sensing. Attached Figure Description

[0030] Figure 1 The image shows a scanning electron microscope (SEM) image of Au-doped particulate SnO2 material with porous V2O5 nanowires prepared by template-assisted hydrothermal method in Example 1 of the present invention (magnification: ×20000).

[0031] Figure 2 The image shows a scanning electron microscope (SEM) image of Au-doped particulate SnO2 material with porous V2O5 nanowires prepared by template-assisted hydrothermal method in Example 1 of the present invention (magnification: ×30000).

[0032] Figure 3 This is the operating curve of the sensor in Embodiment 1 of the present invention. Detailed Implementation

[0033] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0035] As used herein, the terms "and / or," "or / and," and "and / or" encompass any one of two or more of the related listed items, as well as any and all combinations of the related listed items. These arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. It should be noted that when at least three items are connected using at least two conjunctions selected from "and / or," "or / and," and "and / or," it should be understood that, in this application, the technical solution undoubtedly includes solutions connected by "logical AND," and also undoubtedly includes solutions connected by "logical OR."

[0036] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0037] In this application, numerical ranges are referred to as continuous unless otherwise specified, and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0038] This document only specifically discloses some numerical ranges. However, any lower limit can be combined with any upper limit to form an unspecified range; and any lower limit can be combined with other lower limits to form an unspecified range, just as any upper limit can be combined with any other upper limit to form an unspecified range. Furthermore, each individually disclosed point or single value can itself serve as a lower or upper limit and be combined with any other point or single value or with other lower or upper limits to form an unspecified range.

[0039] Unless otherwise specified, the temperature parameters in this application may be either constant temperature processing or processing within a certain temperature range. The constant temperature processing allows temperature fluctuations within the precision range controlled by the instrument, such as ±5℃, ±4℃, ±3℃, ±2℃, or ±1℃.

[0040] In this document, the term "suitable" as used in phrases such as "suitable combination," "suitable method," and "any suitable method" refers to the ability to implement the technical solution of this application, solve the technical problem of this application, and achieve the expected technical effect of this application.

[0041] In this application, terms such as "further," "even more," and "particularly" are used for descriptive purposes and to indicate differences in content, but should not be construed as limiting the scope of protection of this application.

[0042] In this application, "optionally," "optionally," and "optional" mean that something is optional, that is, it means that it is selected from either "with" or "without." If there are multiple "optional" entries in a technical solution, unless otherwise specified, and there are no contradictions or mutual constraints, each "optional" entry shall be independent.

[0043] In the description of the application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0044] Unless otherwise specified, all preparations and tests described herein took place at 25°C.

[0045] The terms “comprising,” “including,” “containing,” “having,” “comprising,” or other variations thereof are intended to cover non-closed inclusion, and no distinction is made between these terms. The term “comprising” means that other steps and ingredients may be added without affecting the final result. The compositions and methods / processes of the present invention comprise, consist of, and substantially consist of the essential elements and limitations described herein, as well as any additional or optional ingredients, components, steps, or limitations described herein. No distinction is made between the terms “efficacy,” “performance,” “effect,” and “potency” herein.

[0046] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions. Unless otherwise specified, all technical features and optional technical features of this application can be combined to form new technical solutions.

[0047] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, but sequentially is preferred.

[0048] In the following embodiments, unless otherwise specified, the raw materials or processing techniques are conventional commercially available raw materials or conventional processing techniques in the art.

[0049] Example 1

[0050] Step 1: Preparation of precursor solution

[0051] (1) In a nitrogen-protected glove box, 5.85 g of Pluronic P123 (molecular weight 5800 g / mol) was dissolved in 200 mL of ultrapure water (resistivity ≥ 18.2 MΩ·cm) and magnetically stirred (800 rpm) for 12 hours to form a transparent micelle solution.

[0052] (2) Weigh 1.17g NH4VO3 (analytical grade, Sigma), add it slowly to the above solution in 5 portions, and adjust the water bath temperature to 35±1℃ at the same time to avoid local oversaturation and vanadate agglomeration.

[0053] (3) Monitor the conductivity of the solution in real time. When the value stabilizes at 450±20μS / cm, it is determined to be completely dissolved (about 30 minutes) and an orange-yellow transparent sol is obtained.

[0054] Step 2: Acid-induced lamellar dissociation

[0055] (1) Use a constant flow pump to add 1M HCl solution dropwise at a rate of 1mL / min, while simultaneously increasing the stirring speed to 1200rpm;

[0056] (2) Monitor the pH of the solution using an online pH meter and control the pH value within the critical range of 2.5-3.0 (if it exceeds this range, NH4VO3 or HCl needs to be added for adjustment);

[0057] (3) Stop the reaction when the solution turns into a bright red colloid (Tyndall effect is obvious), the total time is 30±2 minutes.

[0058] Step 3: Hydrothermal crystallization

[0059] (1) Transfer the mixture to a 100mL polytetrafluoroethylene-lined reactor, and control the filling degree to 70%;

[0060] (2) A three-stage heating program is adopted:

[0061] Phase 1: Room temperature → 100℃ (rate 2℃ / min), hold at this temperature for 1 hour;

[0062] Second stage: 100℃→220℃ (rate 1℃ / min);

[0063] Third stage: Keep warm at 220℃ for 24 hours, with pressure stabilized at 3.8±0.2MPa;

[0064] (3) Allow to cool naturally to room temperature, then centrifuge to collect the precipitate (8000 rpm, 5 minutes).

[0065] Step 4: Post-treatment and thermal activation

[0066] (1) Wash with anhydrous ethanol and deionized water three times by centrifugation (5 minutes each time by ultrasonic dispersion);

[0067] (2) The product was placed in a vacuum drying oven (60℃, 24 hours) to obtain a pale yellow nanowire precursor;

[0068] (3) Gradient annealing is performed in a tube furnace:

[0069] Phase 1: Room temperature → 300℃ (1℃ / min), air atmosphere (flow rate 50 sccm), keep warm for 1 hour;

[0070] Second stage: 300℃→500℃ (5℃ / min), hold for 2 hours to obtain dark green V2O5 nanowires.

[0071] test:

[0072] (1) The porous V2O5 nanowire material prepared in this embodiment using a template-assisted hydrothermal method was characterized by scanning electron microscopy (SEM). Figure 1 , Figure 2 It can be seen that the nanowires have a hierarchical porous structure with uniformly distributed pores.

[0073] (2) The sensor prepared in this embodiment was placed in a resistance detection device at room temperature. After 30 minutes of background SF6 / N2 gas, NO2 gas with a concentration of 10 ppm was introduced for 1100 seconds each time. Then, SF6 / N2 gas was introduced again for 150 seconds for recovery. During this process, the resistance of the sensor changed, and NO2 gas could be detected accordingly.

[0074] Figure 3 This is a repeatable response curve of the sensor to NO2 gas obtained in Example 1. From Figure 3 As can be seen, the response of the sensor in Example 1 increases significantly with the increase of NO2 gas concentration, with a response value of 56.3%. The response value is calculated as (Rg-Ra) / Ra, where Rg is the resistance value after the target gas is introduced, and Ra is the background gas baseline resistance.

[0075] Comparative Example 1:

[0076] The two methods are largely the same as in Example 1, except that the template agent P123 is omitted.

[0077] Step 1: Preparation of precursor solution

[0078] (1) In a nitrogen-protected glove box, weigh 1.17 g of NH4VO3 (analytical grade, Sigma), and slowly add 200 mL of ultrapure water (resistivity ≥18.2 MΩ·cm) in 5 portions, while simultaneously adjusting the water bath temperature to 35±1℃ to avoid local oversaturation leading to vanadate agglomeration.

[0079] (2) Monitor the conductivity of the solution in real time. When the value stabilizes at 450±20μS / cm, it is determined to be completely dissolved (about 30 minutes) and an orange-yellow transparent sol is obtained.

[0080] Step 2: Acid-induced lamellar dissociation

[0081] (1) Use a constant flow pump to add 1M HCl solution dropwise at a rate of 1mL / min, while simultaneously increasing the stirring speed to 1200rpm;

[0082] (2) Monitor the pH of the solution using an online pH meter and control the pH value within the critical range of 2.5-3.0 (if it exceeds this range, NH4VO3 or HCl needs to be added for adjustment);

[0083] (3) Stop the reaction when the solution turns into a bright red colloid (Tyndall effect is obvious), the total time is 30±2 minutes.

[0084] Step 3: Hydrothermal crystallization

[0085] (1) Transfer the mixture to a 100mL polytetrafluoroethylene-lined reactor, and control the filling degree to 70%;

[0086] (2) A three-stage heating program is adopted:

[0087] Phase 1: Room temperature → 100℃ (rate 2℃ / min), hold at this temperature for 1 hour;

[0088] Second stage: 100℃→220℃ (rate 1℃ / min);

[0089] Third stage: Keep warm at 220℃ for 24 hours, with pressure stabilized at 3.8±0.2MPa;

[0090] (3) Allow to cool naturally to room temperature, then centrifuge to collect the precipitate (8000 rpm, 5 minutes).

[0091] Step 4: Post-treatment and thermal activation

[0092] (1) Wash with anhydrous ethanol and deionized water three times by centrifugation (5 minutes each time by ultrasonic dispersion);

[0093] (2) The product was placed in a vacuum drying oven (60℃, 24 hours) to obtain a pale yellow nanowire precursor;

[0094] (3) Gradient annealing is performed in a tube furnace:

[0095] Phase 1: Room temperature → 300℃ (1℃ / min), air atmosphere (flow rate 50 sccm), keep warm for 1 hour;

[0096] Second stage: 300℃→500℃ (5℃ / min), keep warm for 2 hours.

[0097] Referring to Example 1, the product prepared above was tested. The sensor's response value decreased to 3.4% with increasing NO2 gas concentration, which was much lower than the 56.3% in the example. The reason may be that after omitting the template agent P123, V2O5 failed to form a nanowire structure and could not form a porous structure, thus reducing the adsorption sites of the target gas.

[0098] Comparative Example 2:

[0099] Compared with Example 1, most of the process is the same, except that the hydrothermal crystallization process is changed to direct heating to 220°C and holding for 24 hours.

[0100] Step 1: Preparation of precursor solution

[0101] (1) In a nitrogen-protected glove box, 5.85 g of Pluronic P123 (molecular weight 5800 g / mol) was dissolved in 200 mL of ultrapure water (resistivity ≥ 18.2 MΩ·cm) and magnetically stirred (800 rpm) for 12 hours to form a transparent micelle solution.

[0102] (2) Weigh 1.17g NH4VO3 (analytical grade, Sigma), add it slowly to the above solution in 5 portions, and adjust the water bath temperature to 35±1℃ at the same time to avoid local oversaturation and vanadate agglomeration.

[0103] (3) Monitor the conductivity of the solution in real time. When the value stabilizes at 450±20μS / cm, it is determined to be completely dissolved (about 30 minutes) and an orange-yellow transparent sol is obtained.

[0104] Step 2: Acid-induced lamellar dissociation

[0105] (1) Use a constant flow pump to add 1M HCl solution dropwise at a rate of 1mL / min, while simultaneously increasing the stirring speed to 1200rpm;

[0106] (2) Monitor the pH of the solution using an online pH meter and control the pH value within the critical range of 2.5-3.0 (if it exceeds this range, NH4VO3 or HCl needs to be added for adjustment);

[0107] (3) Stop the reaction when the solution turns into a bright red colloid (Tyndall effect is obvious), the total time is 30±2 minutes.

[0108] Step 3: Hydrothermal crystallization

[0109] (1) Transfer the mixture to a 100mL polytetrafluoroethylene-lined reactor, and control the filling degree to 70%;

[0110] (2) Room temperature → 220℃ (rate 1℃ / min), keep warm at 220℃ for 24 hours, and stabilize the pressure at 3.8±0.2MPa;

[0111] (3) Allow to cool naturally to room temperature, then centrifuge to collect the precipitate (8000 rpm, 5 minutes).

[0112] Step 4: Post-treatment and thermal activation

[0113] (1) Wash with anhydrous ethanol and deionized water three times by centrifugation (5 minutes each time by ultrasonic dispersion);

[0114] (2) The product was placed in a vacuum drying oven (60℃, 24 hours) to obtain a pale yellow nanowire precursor;

[0115] (3) Gradient annealing is performed in a tube furnace:

[0116] Phase 1: Room temperature → 300℃ (1℃ / min), air atmosphere (flow rate 50 sccm), keep warm for 1 hour;

[0117] Second stage: 300℃→500℃ (5℃ / min), hold for 2 hours to obtain V2O5 nanowires.

[0118] During the same test, the sensor based on the above V2O5 nanowires showed a decrease in response value to 42.8% as the NO2 gas concentration increased, which was less than 56.3% in the example. This may be because the lack of programmed heating caused some nanomaterials to sinter rapidly, which is not conducive to the formation of porous structures.

[0119] Comparative Example 3:

[0120] The two examples are largely the same as in Example 1, except that template agent P123 is replaced with an equimolar amount of template agent F127.

[0121] Step 1: Preparation of precursor solution

[0122] (1) In a nitrogen-protected glove box, the template agent F127 was dissolved in 200 mL of ultrapure water (resistivity ≥18.2 MΩ·cm) and magnetically stirred (800 rpm) for 12 hours to form a transparent micelle solution.

[0123] (2) Weigh 1.17g NH4VO3 (analytical grade, Sigma), add it slowly to the above solution in 5 portions, and adjust the water bath temperature to 35±1℃ at the same time to avoid local oversaturation and vanadate agglomeration.

[0124] (3) Monitor the conductivity of the solution in real time. When the value stabilizes at 450±20μS / cm, it is determined to be completely dissolved (about 30 minutes) and an orange-yellow transparent sol is obtained.

[0125] Step 2: Acid-induced lamellar dissociation

[0126] (1) Use a constant flow pump to add 1M HCl solution dropwise at a rate of 1mL / min, while simultaneously increasing the stirring speed to 1200rpm;

[0127] (2) Monitor the pH of the solution using an online pH meter and control the pH value within the critical range of 2.5-3.0 (if it exceeds this range, NH4VO3 or HCl needs to be added for adjustment);

[0128] (3) Stop the reaction when the solution turns into a bright red colloid (Tyndall effect is obvious), the total time is 30±2 minutes.

[0129] Step 3: Hydrothermal crystallization

[0130] (1) Transfer the mixture to a 100mL polytetrafluoroethylene-lined reactor, and control the filling degree to 70%;

[0131] (2) A three-stage heating program is adopted:

[0132] Phase 1: Room temperature → 100℃ (rate 2℃ / min), hold at this temperature for 1 hour;

[0133] Second stage: 100℃→220℃ (rate 1℃ / min);

[0134] Third stage: Keep warm at 220℃ for 24 hours, with pressure stabilized at 3.8±0.2MPa;

[0135] (3) Allow to cool naturally to room temperature, then centrifuge to collect the precipitate (8000 rpm, 5 minutes).

[0136] Step 4: Post-treatment and thermal activation

[0137] (1) Wash with anhydrous ethanol and deionized water three times by centrifugation (5 minutes each time by ultrasonic dispersion);

[0138] (2) The product was placed in a vacuum drying oven (60℃, 24 hours) to obtain a pale yellow nanowire precursor;

[0139] (3) Gradient annealing is performed in a tube furnace:

[0140] Phase 1: Room temperature → 300℃ (1℃ / min), air atmosphere (flow rate 50 sccm), keep warm for 1 hour;

[0141] Second stage: 300℃→500℃ (5℃ / min), hold for 2 hours to obtain V2O5 nanowires.

[0142] During the same testing process, the response value of the sensor based on the aforementioned V2O5 nanowires decreased to 39.2% with increasing NO2 gas concentration, which was lower than the 56.3% in the example. This may be because P123 has a smaller molecular weight (~5800), making it prone to forming smaller micelle structures, while F127 has a larger molecular weight (~12600), tending to form larger micelles. Therefore, the product obtained by F127 has a larger pore size and lower specific surface area, reducing the adsorption sites for the target gas.

[0143] Comparative Example 4:

[0144] The process was largely the same as in Example 1, except that hydrochloric acid was replaced with an equimolar concentration of sulfuric acid solution. An amorphous precipitate was ultimately formed, demonstrating that without the synergistic intercalation effect of hydrochloric acid, it is difficult to obtain stable V₂O₅ nanowires.

[0145] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method for preparing porous V₂O₅ nanowires based on a template-assisted hydrothermal method, characterized in that, Includes the following steps: S1. Under nitrogen protection, NH4VO3 was weighed and added to the template agent aqueous solution to obtain an orange-yellow transparent solution. S2. Add hydrochloric acid solution dropwise to the orange-yellow transparent solution obtained in S1, so that the solution gradually turns into a bright red colloid, and maintain the pH value of the system in the range of 2.5-3.0; S3. The mixed solution obtained in S2 is transferred to a high-pressure reactor, heated and subjected to hydrothermal reaction, then cooled, separated and washed. The precipitate is dehydrated and then heat-annealed in air to obtain V2O5 nanowires, which is the target product.

2. The method for preparing porous V₂O₅ nanowires based on template-assisted hydrothermal method according to claim 1, characterized in that, In S1, the template agent is Pluronic P123.

3. The method for preparing porous V₂O₅ nanowires based on template-assisted hydrothermal method according to claim 1, characterized in that, In S1, the ratio of NH4VO3 to the template agent aqueous solution is (9-11) mmol: (55-65) mL, and the concentration of the template agent aqueous solution is 4-6 wt%.

4. The method for preparing porous V₂O₅ nanowires based on template-assisted hydrothermal method according to claim 1, characterized in that, In S2, the concentration of the hydrochloric acid solution is 0.8–1.2 M.

5. The method for preparing porous V₂O₅ nanowires based on template-assisted hydrothermal method according to claim 1, characterized in that, In S3, the hydrothermal reaction process is as follows: first, the temperature is raised from room temperature to 100℃ and held for 1 hour; then the temperature is raised to 210-230℃ and held for 20-28 hours, while maintaining the pressure at 3.5-4.2 MPa.

6. The method for preparing porous V₂O₅ nanowires based on template-assisted hydrothermal method according to claim 1, characterized in that, In S3, the hot annealing process is as follows: First, raise the temperature from room temperature to 300℃ and hold it for 0.5 to 1.5 hours. Then, continue to raise the temperature to 490 to 510℃ and hold it for 1.5 to 2.5 hours.

7. The method for preparing porous V₂O₅ nanowires based on template-assisted hydrothermal method according to claim 1, characterized in that, In S3, the washing process is as follows: wash three times each with anhydrous ethanol and deionized water.

8. The method for preparing porous V₂O₅ nanowires based on template-assisted hydrothermal method according to claim 1, characterized in that, In S3, the dehydration process is as follows: the precipitate is dehydrated in a vacuum drying oven at 60±2℃ for 24 hours.

9. A porous V₂O₅ nanowire material prepared by a template-assisted hydrothermal method, wherein the material is prepared by the method described in any one of claims 1-8, characterized in that, The porous V2O5 nanowire material has a hierarchical porous structure with uniformly distributed pores.

10. The application of the porous V2O5 nanowire material prepared by template-assisted hydrothermal method as described in claim 9 as a gas-sensitive material for detecting decomposition components of SF6 / N2 gas.

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