Method for preparing pine needle-shaped zinc tin oxide by using electrostatic spinning and hydrothermal method, and product and application thereof

Abstract

The invention discloses a method for preparing pine needle-shaped zinc tin oxide by electrostatic spinning and a hydrothermal method as well as a product and application of the pine needle-shaped zinc tin oxide, and belongs to the technical field of sensing materials. A hexagonal-prism-shaped zinc oxide substrate material is prepared through an electrostatic spinning technology, needle-shaped tin oxide grows on the surface of the hexagonal-prism-shaped zinc oxide substrate material in combination with a hydrothermal method, and the pine needle-shaped zinc tin oxide is obtained. The method is simple to operate, non-toxic, low in cost and suitable for large-scale production. The prepared material has a high specific surface area, a unique heterojunction interface can be used as a channel for gas diffusion and electron transfer, the interface has rich oxygen vacancies, and the electron capture and gas ion adsorption conversion capability is remarkably accelerated. The pine needle-shaped zinc tin oxide is used for preparing a gas sensitive sensor, and has a wide application prospect in the related fields of photocatalysis, clean energy, environmental governance and the like.

Description

Technical Field

[0001] The invention relates to the technical field of sensing materials, and in particular to a method for preparing pine needle-shaped zinc tin oxide by electrostatic spinning and hydrothermal method, and a product and application thereof. Background Art

[0002] With the development of industry, air pollution caused by exhaust gas emissions has become more and more serious, especially the increasing emissions of harmful gases such as NO2 and H2S, which pose a serious threat to human health. For example, when the concentration of NO2 in the air reaches 53 ppb, it is enough to have adverse effects on human health. Therefore, environmental governance issues have become a focus of universal concern. In order to effectively curb air pollution and protect human health, this field urgently needs to develop gas sensors that can achieve low detection limits and fast response at room temperature. This has become a key technical problem that needs to be solved in the current field of gas sensing.

[0003] Zinc oxide, as an n-type semiconductor, has efficient electron transfer ability, excellent mechanical strength and high chemical stability and is widely used in the field of gas detection. However, single metal oxide sensors face challenges such as high operating temperature, low responsiveness and long response / recovery time in practical applications. In order to solve these problems, researchers have begun to explore new ways to improve the inherent properties of zinc-based materials, including morphology regulation, improved synthesis methods and preparation of materials of different dimensions. Electrospinning technology, as a simple, versatile and cost-effective process, is an ideal choice for large-scale production of one-dimensional zinc oxide. The zinc-based materials prepared by this technology not only have rich and uniform pores, but also have a large specific surface area and excellent connectivity. These characteristics enable zinc-based materials to provide more active sites when reacting with harmful gas molecules at the interface, thereby promoting the reaction, while showing excellent sensitivity, laying a solid foundation for building high-performance composite structures.

[0004] In recent years, the strategy of composite doping of zinc-based materials with other high-performance materials has attracted much attention. This composite doping method aims to combine the excellent properties of the two materials to prepare high-performance, high-selectivity, and rapid charge transfer and separation sensing materials. The choice of this strategy is based on the environmental friendliness and economy of zinc-based materials, as well as the significant influence of their structure and morphology on catalytic performance. In particular, those zinc-based materials with excellent hollow structures, their high specific surface area allows the electrolyte to more easily enter the catalytic site and achieve effective mass diffusion, thereby exhibiting excellent catalytic performance.

[0005] The use of electrospinning technology to prepare zinc oxide-based materials is an emerging processing method. For example, the Chinese invention patent with publication number CN116770460A discloses a method for preparing Fe-doped zinc oxide nanofibers by electrospinning. The specific method is: 1) preparing a solution A containing a polymer and a solution containing Zn 2+ and Fe 3+ Solution B; 2) adding anhydrous ethanol to the mixture of solution A and solution B to obtain the precursor liquid C for electrospinning; 3) placing the precursor liquid C in an electrospinning device for electrospinning to obtain a spinning sample; 4) sintering the spinning sample to obtain Fe-doped zinc oxide nanofibers. This invention doped Fe into zinc oxide nanofibers, greatly refined the diameter of the nanofibers, increased their specific surface area, and reduced the bandgap width of ZnO, thereby increasing the photocatalytic degradation of methylene blue. However, the application of zinc oxide-based materials in different fields needs to be optimized in a targeted manner. Compared with the photocatalytic degradation of methylene blue, zinc oxide-based materials need to have good stability in the field of gas sensors; in addition, the volatility and diffusivity of harmful gas molecules are generally much higher than those of liquids, which means that when used in gas sensors, they need to have higher reactivity to detect rapid changes in parameters and meet the requirements of excellent sensing performance and detection sensitivity.

[0006] In summary, providing a zinc oxide-based material to meet the needs of gas molecule sensing and detection, and solving the shortcomings of existing zinc oxide semiconductor materials such as high operating temperature, low responsiveness, and long response / recovery time, has positive significance for the field of gas sensitive sensing. Summary of the invention

[0007] In view of the above-mentioned defects of the prior art, in the first aspect of the present invention, a method for preparing pine needle-shaped zinc tin oxide by electrospinning and hydrothermal method is provided, which is simple to operate, non-toxic and low-cost, and comprises the following steps: (1) Preparation of hexagonal zinc oxide: Dissolving zinc salt and polyvinyl pyrrolidone in a solvent to obtain a precursor; spinning the precursor by electrostatic spinning to obtain a silk thread; calcining the silk thread to obtain hexagonal zinc oxide; (2) Preparation of needle-like tin oxide: Tin salt is weighed according to a mass ratio of zinc salt to tin salt of 1:5-5:1, and the tin salt is dissolved in a solvent to prepare a tin salt solution; sodium hydroxide is added to adjust the pH of the tin salt solution to 6-12, and then hexagonal zinc oxide is added and a hydrothermal reaction is carried out at 80-200 ° C for 6-15 h to grow needle-like tin oxide on the surface of the hexagonal zinc oxide; after the hydrothermal reaction is completed, the product is recovered and purified to obtain pine needle-like zinc tin oxide.

[0008] Zinc salts generally have the advantages of good solubility and wide sources, and those skilled in the art can select a suitable type according to the needs and actual conditions of the electrospinning process. For example, zinc sulfate, zinc acetate, zinc nitrate, zinc chloride, zinc oxalate and the like fully meet the above preparation requirements and are particularly suitable zinc salts for this process.

[0009] Preferably, in step (1), the zinc salt includes at least one of zinc sulfate, zinc acetate, zinc nitrate, zinc chloride and zinc oxalate.

[0010] Polyvinyl pyrrolidone is a non-ionic polymer compound with good solubility and film-forming properties, which can form a uniform solution or solution system during electrospinning. In electrospinning, the molecular weight of polyvinyl pyrrolidone can affect the diameter of the final fiber. Polyvinyl pyrrolidone with a lower molecular weight usually leads to finer fibers because they have a lower viscosity in the solution, which is conducive to the stretching of the spinning solution and the formation of filaments. On the contrary, polyvinyl pyrrolidone with a higher molecular weight will produce thicker fibers because it increases the viscosity of the solution and reduces the stretching effect during spinning. For the needs of preparation, the molecular weight of polyvinyl pyrrolidone is appropriately controlled within a suitable range.

[0011] Preferably, in step (1), the molecular weight of polyvinyl pyrrolidone is 60,000-130,000.

[0012] The solution for electrospinning is usually a mixture of a polymer and a suitable solvent. During the electrospinning process, a high voltage is applied to the solution so that the solution forms a jet stream under the action of the electric field, and then stretched into nano-scale fibers. The solvent is selected according to the solubility of the selected polymer and the raw material. Common solvents include water, ethanol, N, N-dimethylformamide, tetrahydrofuran, hexafluoroisopropanol, trifluoroacetic acid, acetic acid aqueous solution, etc. Based on the raw material type of the present invention, a mixture of N, N-dimethylformamide and at least one of water, methanol, and ethanol is a particularly suitable choice.

[0013] Preferably, in step (1), the solvent comprises a mixed solvent formed by N,N-dimethylformamide and at least one of water, methanol and ethanol.

[0014] Preferably, in step (1), in the precursor, the concentration of zinc salt is 0.5-300 mg / mL; the concentration of polyvinyl pyrrolidone is 0.5-300 mg / mL.

[0015] Preferably, in step (1), during electrospinning, the distance between the syringe and the collecting electrode is 5-20 cm; the voltage of electrospinning is 5-20 kV; and the propulsion rate of the precursor is 0.001-0.01 mL / min.

[0016] Calcination can remove the polymer in the wire by ablation and leave the target hexagonal zinc oxide. The heating rate of calcination is appropriately controlled within a suitable range, which is conducive to the zinc salt forming the target hexagonal structure and avoiding defects caused by too fast heating.

[0017] Preferably, in step (1), the calcination temperature is 350-600°C and the calcination time is 1-5 h.

[0018] Preferably, in step (1), the heating rate of calcination is 0.1-2 °C / min.

[0019] Similar to the principles for selecting zinc salts and solvent types, those skilled in the art can select appropriate tin salt types and solvents based on the above principles.

[0020] Preferably, in step (2), the tin salt includes at least one of stannous sulfate, tin nitrate, stannous chloride dihydrate, and tin acetate.

[0021] Preferably, in step (2), the solvent includes at least one of water, methanol and ethanol.

[0022] Preferably, in step (2), the concentration of tin salt in the tin salt solution is 0.1-300 mg / mL.

[0023] In the second aspect of the present invention, there is provided a pine needle-shaped zinc tin oxide with fast electron capture speed and high gas ion adsorption and conversion capacity, which is prepared by the method of the first aspect of the present invention, and its structure includes hexagonal zinc oxide and needle-shaped tin oxide grown on its surface.

[0024] In the third aspect of the present invention, there is provided an application of the pine needle-shaped zinc tin oxide according to the second aspect of the present invention, specifically, an application as a semiconductor material in the preparation of a gas sensor.

[0025] Based on the above technical scheme, the design concept and principle of the present invention is to adopt simple, non-toxic and low-cost electrospinning and hydrothermal processes, and control the mass ratio of tin salt to zinc salt, the heating temperature and heating time of the hydrothermal reaction to sequentially complete the preparation of hexagonal zinc oxide and the growth of needle-like tin oxide on its surface, forming a structure similar to that of pine needles growing on branches, thereby obtaining pine needle-like zinc tin oxide.

[0026] Specifically, the silk prepared by electrospinning is a mixture of polymer and zinc salt. After calcination, the carbon structure is removed and zinc oxide is left. The zinc salt self-stacking forms a hexagonal structure during the generation process. The formation of a hexagonal zinc oxide structure can bring many advantages when synthesizing samples, including the following: 1) Increase the specific surface area: The hexagonal structure usually has a larger specific surface area, which means that it has more active surface area per unit mass or volume, which is beneficial to improve the rate and efficiency of chemical reactions; 2) Improve the photoelectrocatalytic performance: The hexagonal zinc oxide structure has good photoelectrocatalytic performance, can effectively absorb light energy and promote photocatalytic reactions, such as water decomposition, photocatalytic degradation of organic matter, etc.; 3) Optimize the optical effect: The hexagonal structure has special optical properties, which can improve the utilization efficiency of light by controlling the refraction, reflection and absorption effects of light, which is helpful for some optical applications; 4) Enhance the electrochemical performance: The hexagonal structure may provide more active sites and ion transport channels, which is beneficial to improve the electrochemical energy storage and sensing performance.

[0027] In the field of gas sensors, the hexagonal zinc oxide structure can bring the following advantages: 1) Enhanced gas-sensing performance: Hexagonal zinc oxide has a large specific surface area and a special structure, which can provide more active surfaces and increase the chances of gas molecule adsorption, thereby improving the sensitivity and response speed of gas sensors; 2) Improved selectivity: Zinc oxide structures with specific morphologies may have different selective adsorption capabilities for different gases. By regulating the characteristics of the hexagonal structure, high-selective detection of specific gases can be achieved, thereby improving the detection accuracy of gas sensors; 3) Stability and regeneration: The hexagonal structure may have good stability and regeneration, which is conducive to the long-term stable operation and multiple use of the sensor; 4) Fast response: Due to the large surface area and permeability of the hexagonal structure, gas molecules can quickly diffuse to the active sites, making the sensor have a faster response speed; 5) Anti-interference ability: By optimizing the hexagonal structure, the anti-interference ability of the sensor can be improved, the impact of external environmental factors on the sensor performance can be reduced, and the stability and reliability of the sensor can be improved.

[0028] During the hydrothermal reaction, the growth of needle-like tin oxide is the key, and how to avoid chaotic stacking is the core operation of this process. The inventor controls the reaction conditions to affect the diffusion rate and precipitation rate of ions in the solution, thereby controlling the growth direction and morphology of the crystal. This precise crystal growth control helps to achieve the growth of needle-like structures on hexagonal zinc oxide. Sodium hydroxide dissolves under the action of the solvent to produce sodium ions and hydroxide ions; tin salts dissolve to produce tin ions, which react with hydroxide ions at the high temperature of the hydrothermal reaction to generate needle-like tin oxide.

[0029] Pine needle-shaped zinc tin oxide has a delicate structure like a pine tree in nature at the microscopic level. Hexagonal zinc oxide has a very rich specific surface area. On this basis, the integration of needle-shaped tin oxide further increases the specific surface area of ​​the composite material and constructs a unique heterojunction interface between the two. At the heterojunction interface of zinc oxide and tin oxide, due to the mismatch of the band structure, band offset and electron confinement effects will be formed. This leads to the aggregation or diffusion of electrons at the interface, resulting in processes such as electron migration and electron-hole recombination. These effects will affect the electron transport properties, carrier lifetime and photoelectric properties at the heterojunction interface. In addition, the heterojunction interface of zinc oxide and tin oxide can also induce effects such as interface defects, charge transfer and local stress fields, further optimizing the performance and stability of the device.

[0030] The pine needle-shaped zinc tin oxide structure can not only quickly capture gas molecules in a short time, but also show excellent efficiency in the diffusion and absorption process of gas molecules. What is more worth mentioning is that this special pine needle-shaped form performs excellently in gas capture, and realizes the refraction and absorption of light through the gaps between each "pine needle". This characteristic makes the zinc tin oxide material of the present invention have great application potential in related fields such as photocatalysis.

[0031] Compared with the prior art, the present invention has the following advantages and beneficial effects: The invention provides a method for preparing pine needle-shaped zinc tin oxide by electrostatic spinning and hydrothermal method, which is simple to operate, non-toxic, low-cost and suitable for large-scale production.

[0032] The present invention provides a pine needle-shaped zinc tin oxide, which has a high specific surface area and a unique heterojunction interface, can serve as a channel for gas diffusion and electron transfer, and has abundant oxygen vacancies at the interface, which significantly accelerates the ability of electron capture and gas ion adsorption conversion.

[0033] The present invention provides an application of pine needle-shaped zinc tin oxide for preparing a gas sensor, which has broad application prospects in photocatalysis, clean energy, environmental management and other related fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a scanning electron microscope (SEM) image of the pine needle-shaped zinc tin oxide of Example 1; Figure 2 This is a transmission electron microscope (TEM) image of the pine needle-shaped zinc tin oxide of Example 1; Figure 3The X-ray energy spectrum (energy dispersive spectrometer, EDS) of the pine needle-shaped zinc tin oxide of Example 1; Figure 4 The dynamic curve of the sensor resistance change of the pine needle-shaped zinc tin oxide in Example 1 at room temperature for different concentrations of H2S gas. DETAILED DESCRIPTION

[0035] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples. The experimental methods in the following examples without specifying specific conditions are carried out according to conventional methods and conditions, or selected according to the product specifications.

[0036] Example 1 The method for preparing pine needle-shaped zinc tin oxide by electrospinning and hydrothermal method comprises the following steps: (1) Preparation of hexagonal zinc oxide: Weigh 0.5 g zinc acetate; measure 10 mL of anhydrous ethanol and 10 mL of N,N-dimethylformamide and mix them evenly in a beaker to obtain a mixed solvent; weigh 2.501 g of polyvinyl pyrrolidone with a molecular weight of 130000; slowly add zinc acetate and polyvinyl pyrrolidone to the mixed solvent at room temperature and stir evenly for 30 min; transfer the obtained colloidal precursor to the electrospinning instrument, the distance between the syringe and the collector is 10 cm, the constant voltage is 15 kV, and the solution advancement rate is 0.004 mL / min; after 6 h of electrospinning, the obtained product is calcined in a muffle furnace at a temperature of 500 °C, a heating rate of 1 °C / min, and a constant temperature time of 2 h to obtain hexagonal zinc oxide, denoted as ZO.

[0037] (2) Preparation of needle-like tin oxide: Weigh 0.1 g of stannous chloride dihydrate; weigh 1.5 g of sodium hydroxide; measure 50 mL of deionized water; weigh 0.5 g of ZO; add stannous chloride dihydrate, sodium hydroxide and ZO into deionized water at room temperature and stir evenly for 30 min; transfer the obtained solution into a 100 mL stainless steel polytetrafluoroethylene-lined autoclave and perform hydrothermal reaction at 200 ℃ for 15 h; after cooling, filter and thoroughly wash with deionized water and anhydrous ethanol, and dry in ambient air at 60 ℃ to obtain pine needle-like zinc tin oxide.

[0038] The microstructure of pine needle-shaped zinc tin oxide was observed by SEM and TEM. The results are as follows: Figure 1 and Figure 2 As shown. Figure 1It can be seen that through SEM observation, the image shows obvious morphological features of nanorods and needle-like structures, confirming the existence of pine needle-like morphology. Each hexagonal zinc oxide nanorod is tightly wrapped by tin oxide thorns, forming a typical pine needle-like morphology. These tin oxides grow on the non-polar plane of zinc oxide and have a length of 0.3-0.5 μm. And the above observation information can evaluate the interface bonding between tin oxide and hexagonal zinc oxide nanorods. Its good interface bonding helps to improve the stability and electron transfer efficiency of the material, thereby affecting the performance of the material. This pine needle-like structure has a high specific surface area, good interface bonding and excellent electron transfer efficiency, which provides a basis for improving the optoelectronic performance of the material and expanding its application. By Figure 2 It can be seen that uniform tin oxide grows vertically on the non-polarized plane of zinc oxide, confirming the SEM observation results.

[0039] In order to understand the element distribution of pine needle-shaped zinc tin oxide, EDS was used for energy spectrum analysis, and the results are as follows: Figure 3 shown. Figure 3 EDS analysis confirmed that Sn, Zn and O elements coexist in pine needle-like zinc tin oxide, and the mass percentages of Zn, Sn and O were 27.39%, 32.54% and 40.07%, respectively.

[0040] Example 2 The method for preparing pine needle-shaped zinc tin oxide by electrospinning and hydrothermal method comprises the following steps: (1) Preparation of hexagonal zinc oxide: Weigh 1.0 g zinc nitrate; take 10 mL anhydrous ethanol and 10 mL N,N-dimethylformamide and mix them evenly in a beaker to obtain a mixed solvent; weigh 2.501 g polyvinyl pyrrolidone with a molecular weight of 130000; slowly add zinc nitrate and polyvinyl pyrrolidone to the mixed solvent at room temperature and stir evenly for 30 min; transfer the obtained colloidal precursor to the electrospinning instrument, the distance between the syringe and the collector is 10 cm, the constant voltage is 15 kV, and the solution advancement rate is 0.004 mL / min; after 6 h of electrospinning, the obtained product is calcined in a muffle furnace at a temperature of 600 °C, a heating rate of 2 °C / min, and a constant temperature time of 2 h to obtain hexagonal zinc oxide, denoted as ZO1; (2) Preparation of needle-like tin oxide: Weigh 0.4 g of tin acetate; weigh 1.5 g of sodium hydroxide; measure 50 mL of deionized water; weigh 1.0 g of ZO1; add tin acetate, sodium hydroxide and ZO1 into deionized water at room temperature and stir evenly for 30 min; transfer the obtained solution into a 100 mL stainless steel polytetrafluoroethylene-lined autoclave and perform hydrothermal reaction at 200 °C for 15 h; after cooling, filter and thoroughly wash with deionized water and anhydrous ethanol, and dry in ambient air at 60 °C to obtain pine needle-like zinc tin oxide.

[0041] Example 3 The method for preparing pine needle-shaped zinc tin oxide by electrospinning and hydrothermal method comprises the following steps: (1) Preparation of hexagonal zinc oxide: Weigh 1.5g zinc sulfate; take 10mL anhydrous ethanol and 10mL N,N-dimethylformamide and mix them evenly in a beaker to obtain a mixed solvent; weigh 2.501g polyvinyl pyrrolidone with a molecular weight of 130000; slowly add zinc sulfate and polyvinyl pyrrolidone to the mixed solvent at room temperature and stir evenly for 30 minutes; transfer the obtained colloidal precursor to the electrospinning instrument, the distance between the syringe and the collector is 10cm, the constant voltage is 15kV, and the solution advancement rate is 0.004mL / min; after 6h of electrospinning, the obtained product is calcined in a muffle furnace at a temperature of 400℃, a heating rate of 0.2℃ / min, and a constant temperature time of 4h to obtain hexagonal zinc oxide, denoted as ZO2; (2) Preparation of needle-like tin oxide: Weigh 1.2 g of stannous sulfate; weigh 1.5 g of sodium hydroxide; measure 50 mL of deionized water; weigh 1.5 g of ZO2; add stannous sulfate, sodium hydroxide and ZO2 into deionized water at room temperature and stir evenly for 30 min; transfer the obtained solution into a 100 mL stainless steel polytetrafluoroethylene-lined autoclave and perform hydrothermal reaction at 200 °C for 15 h; filter after cooling, and wash thoroughly with deionized water and anhydrous ethanol, and dry in ambient air at 60 °C to obtain pine needle-like zinc tin oxide.

[0042] Example 4 The method for preparing pine needle-shaped zinc tin oxide by electrospinning and hydrothermal method comprises the following steps: (1) Preparation of hexagonal zinc oxide: Weigh 2.0g zinc chloride; take 10mL anhydrous ethanol and 10mL N,N-dimethylformamide and mix them evenly in a beaker to obtain a mixed solvent; weigh 2.501g polyvinyl pyrrolidone with a molecular weight of 130000; slowly add zinc chloride and polyvinyl pyrrolidone to the mixed solvent at room temperature and stir evenly for 30 minutes; transfer the obtained colloidal precursor to the electrospinning instrument, the distance between the syringe and the collector is 10cm, the constant voltage is 15kV, and the solution advancement rate is 0.004mL / min; after 6h of electrospinning, the obtained product is calcined in a muffle furnace at a temperature of 350℃, a heating rate of 0.5℃ / min, and a constant temperature time of 5h to obtain hexagonal zinc oxide, denoted as ZO3; (2) Preparation of needle-like tin oxide: Weigh 2.0 g of tin nitrate; weigh 1.5 g of sodium hydroxide; measure 50 mL of deionized water; weigh 1.5 g of ZO3; add tin nitrate, sodium hydroxide and ZO3 into deionized water at room temperature and stir evenly for 30 min; transfer the obtained solution into a 100 mL stainless steel polytetrafluoroethylene-lined autoclave and perform hydrothermal reaction at 200 ℃ for 15 h; after cooling, filter and thoroughly wash with deionized water and anhydrous ethanol, and dry in ambient air at 60 ℃ to obtain pine needle-like zinc tin oxide.

[0043] Example 5 This example is an application example of pine needle-shaped zinc tin oxide. The pine needle-shaped zinc tin oxide prepared in Example 1 was used to study the dynamic curve of sensor resistance change for different concentrations of H2S gas at room temperature when it was used as a gas sensor. According to the definition, the response value (S) of the test is expressed as: S = (R a -R g ) / R a ; Among them, R a , R g Respectively represent the resistance of the sensor in air and target gas.

[0044] Test results such as Figure 4 As shown. Figure 4It is known that the response of the best sample to H2S (concentration = 100 ppm) at room temperature is 0.71. The ratio of the resistance of the gas sensor in the target gas to the resistance in the air can be calculated through the test results of the response value. This ratio can be used to evaluate the sensitivity of the sensor to H2S. In addition, the response time and recovery time are also important indicators of the performance of gas sensors, which reflect the rapid response and recovery capabilities of the sensor to the target gas. In this case, the response time of the gas sensor to H2S is 5.6 s and the recovery time is 98 s, which means that the gas sensor can respond and detect H2S quickly, and can also quickly return to normal when the air is switched back. Finally, the minimum detection concentration of the gas sensor is 0.5 ppm, which means that it can detect extremely low concentrations of H2S, which is very important for monitoring and controlling the concentration of harmful gases in the environment.

[0045] In summary, the present invention proposes an innovative method combining electrospinning and hydrothermal method for preparing a zinc oxide tin composite material with a pine needle-like structure. The hexagonal zinc oxide base material is prepared by electrospinning technology, which is unique in that it has an extremely rich specific surface area. On this basis, the clever integration of needle-like tin oxide not only further increases the specific surface area of ​​the composite material, but also constructs a unique heterojunction interface between the two. This interface can serve as a channel for gas diffusion and electron transfer, and there are abundant oxygen vacancies at the interface, which significantly accelerates the ability of electron capture and gas ion adsorption conversion. This preparation process is simple, versatile and low-cost, and has great potential for application in related fields.

[0046] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A method for preparing pine needle-shaped zinc tin oxide by electrospinning and hydrothermal method, characterized in that: The steps include: (1) Preparation of hexagonal zinc oxide: Dissolving zinc salt and polyvinyl pyrrolidone in a solvent to obtain a precursor; spinning the precursor by electrostatic spinning to obtain a silk thread; calcining the silk thread to obtain hexagonal zinc oxide; (2) Preparation of needle-like tin oxide: Tin salt is weighed according to a mass ratio of zinc salt to tin salt of 1:5-5:1, and the tin salt is dissolved in a solvent to prepare a tin salt solution; sodium hydroxide is added to adjust the pH of the tin salt solution to 6-12, and then hexagonal zinc oxide is added and a hydrothermal reaction is carried out at 80-200 ° C for 6-15 h to grow needle-like tin oxide on the surface of the hexagonal zinc oxide; after the hydrothermal reaction is completed, the product is recovered and purified to obtain pine needle-like zinc tin oxide.

2. The method for preparing pine needle-shaped zinc tin oxide by electrospinning and hydrothermal method according to claim 1, characterized in that: In the step (1), the zinc salt includes at least one of zinc sulfate, zinc acetate, zinc nitrate, zinc chloride and zinc oxalate; and the solvent includes a mixed solvent formed by N,N-dimethylformamide and at least one of water, methanol and ethanol.

3. The method for preparing pine needle-shaped zinc tin oxide by electrospinning and hydrothermal method according to claim 1, characterized in that: In the step (1), the molecular weight of polyvinyl pyrrolidone is 60,000-130,000.

4. The method for preparing pine needle-shaped zinc tin oxide by electrospinning and hydrothermal method according to claim 1, characterized in that: In the step (1), in the precursor, the concentration of zinc salt is 0.5-300 mg / mL; the concentration of polyvinyl pyrrolidone is 0.5-300 mg / mL.

5. The method for preparing pine needle-shaped zinc tin oxide by electrospinning and hydrothermal method according to claim 1, characterized in that: In the step (1), during electrospinning, the distance between the syringe and the collecting electrode is 5-20 cm; the voltage of electrospinning is 5-20 kV; and the propulsion rate of the precursor is 0.001-0.01 mL / min.

6. The method for preparing pine needle-shaped zinc tin oxide by electrospinning and hydrothermal method according to claim 1, characterized in that: In the step (1), the calcination temperature is 350-600°C, the time is 1-5 h, and the calcination heating rate is 0.1-2°C / min.

7. The method for preparing pine needle-shaped zinc tin oxide by electrospinning and hydrothermal method according to claim 1, characterized in that: In the step (2), the tin salt includes at least one of stannous sulfate, tin nitrate, stannous chloride dihydrate, and tin acetate; and the solvent includes at least one of water, methanol, and ethanol.

8. The method for preparing pine needle-shaped zinc tin oxide by electrospinning and hydrothermal method according to claim 1, characterized in that: In the step (2), the concentration of the tin salt in the tin salt solution is 0.1-300 mg / mL.

9. A pine needle-shaped zinc tin oxide, characterized in that: The zinc oxide is prepared by the preparation method according to any one of claims 1 to 8, and the structure includes hexagonal zinc oxide and needle-like tin oxide grown on the surface thereof.

10. An application of the pine needle-shaped zinc tin oxide as claimed in claim 9, characterized in that: Application as semiconductor material in the preparation of gas sensors.

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