A tin dioxide / indium oxide heterojunction nanofiber gas-sensitive material and a preparation method thereof
By constructing tin dioxide/indium oxide heterojunction nanofiber materials, the problems of high operating temperature and low response value of pure tin dioxide gas-sensitive materials were solved, achieving high sensitivity and rapid response detection of triethylamine, which is suitable for real-time monitoring in complex environments.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- RES INST OF CHEM DEFENSE PLA ACAD OF MILITARY SCI
- Filing Date
- 2026-03-18
- Publication Date
- 2026-05-29
AI Technical Summary
Existing pure tin dioxide gas-sensitive materials have high operating temperatures and low response values for triethylamine, making it difficult to achieve high sensitivity and rapid response detection.
By employing electrospinning technology combined with pyrolysis derivatization, tin dioxide/indium oxide heterojunction nanofibers are constructed to form a hollow structure, thereby increasing the specific surface area and surface active sites and improving gas-sensing performance.
Achieving high sensitivity, rapid response, and excellent selectivity for triethylamine at lower temperatures reduces sensor power consumption and improves long-term stability.
Smart Images
Figure CN122105683A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of gas sensing and detection technology, specifically relating to a tin dioxide / indium oxide heterojunction nanofiber gas-sensitive material, its preparation method, and its application. Background Technology
[0002] Triethylamine, a typical toxic and harmful volatile organic compound, is widely used in organic synthesis, as a solvent, polymerization inhibitor, preservative, and raw material for the production of synthetic dyes. It is also released from dead seafood and wastewater. When humans and animals are exposed to triethylamine, it severely irritates the respiratory tract; inhalation can cause nausea, headache, pulmonary edema, and even death. According to the standards of the American Conference of American Industrial Hygienes, the short-term and time-weighted average permissible concentrations of triethylamine in the workplace are 15 ppm and 10 ppm, respectively. Therefore, developing a novel sensing material with low detection limits, high sensitivity, and good selectivity for real-time monitoring of triethylamine in complex working environments is of significant practical importance.
[0003] Tin dioxide, a pale gray, pale yellow, or white powder, is a multifunctional metal oxide semiconductor with numerous research and applications. The sensitivity of semiconductor gas sensors to the target gas primarily involves a series of processes, including the adsorption, desorption, diffusion, and surface reactions of oxygen and the target gas. Since single semiconductor materials exhibit significant characteristics only in certain aspects, it is difficult to simultaneously possess strong adsorption / desorption properties, selectivity, and stability. To overcome the limitations of single metal oxides in gas sensors, researchers have prepared multi-component metal oxide composite materials with different dispersion states, such as tin dioxide-zinc oxide and tin dioxide-copper oxide. These materials utilize heterogeneous structures or synergistic effects to improve pure-phase tin dioxide semiconductor gas-sensitive materials, achieving a synergistic effect ("1+1>2"), and are widely used in gas sensors. However, existing composite materials still suffer from problems such as high operating temperatures, slow response recovery speeds, or insufficient selectivity. Further exploration of novel structures and compositions is needed to reduce operating temperatures and improve response values and selectivity. Summary of the Invention
[0004] (a) Technical problems to be solved This invention aims to solve the technical problems of high operating temperature and low response value of existing pure tin dioxide gas-sensitive materials to triethylamine, and provides a tin dioxide / indium oxide heterojunction nanofiber gas-sensitive material and its preparation method that can achieve high sensitivity, rapid response and excellent selectivity for triethylamine detection at a lower temperature.
[0005] (II) Technical Solution To address the aforementioned problems, this invention proposes a tin dioxide / indium oxide heterojunction nanofiber gas-sensitive material and its preparation method. The core concept involves using stannous chloride and indium nitrate as raw materials, a ternary mixed solution formed by N,N-dimethylformamide, anhydrous ethanol, and glacial acetic acid as a solvent, and polyvinylpyrrolidone as a polymer template. Electrospinning combined with pyrolysis derivatization is employed to construct tin dioxide / indium oxide heterojunction nanofibers with a hollow structure. This hollow porous structure endows the material with a large specific surface area, increases surface active sites, promotes oxygen vacancy formation, and enhances the adsorbed oxygen concentration participating in the gas-sensing reaction, thereby significantly improving its gas-sensing performance for triethylamine.
[0006] The method for preparing tin dioxide / indium oxide heterojunction nanofiber gas-sensitive materials provided by the present invention includes the following steps: S1. Preparation of mixed solvent: N,N-dimethylformamide, anhydrous ethanol and glacial acetic acid are mixed in a volume ratio of 6:3:1 and stirred evenly at a stirring speed of 500 r / min to obtain a mixed solution.
[0007] S2. Preparation of spinning solution: Add stannous chloride and indium nitrate to the above mixed solution in a molar ratio of 4:1 and stir to dissolve; then add polyvinylpyrrolidone and continue stirring for 4-8 hours under magnetic stirring at 500 r / min until a uniform and clear spinning precursor solution is formed.
[0008] S3. Electrospinning: The spinning solution is loaded into a plastic syringe, a needle is installed, and the parameters are set before electrospinning is performed. The composite fiber nonwoven fabric is collected on the receiving device, which is the precursor of tin dioxide / indium oxide heterojunction nanofibers.
[0009] S4. Heat treatment: The collected composite fiber nonwoven fabric is heated to 600℃ in air at a heating rate of 2℃ / min, held at that temperature for 1h, and then naturally cooled to room temperature to obtain a hollow tin dioxide / indium oxide heterojunction nanofiber gas-sensitive material composed of tin dioxide and indium oxide particles.
[0010] This invention also provides a tin dioxide / indium oxide heterojunction nanofiber gas-sensitive material prepared by the above method. The X-ray diffraction pattern of this material shows the simultaneous presence of characteristic diffraction peaks of both tin dioxide and indium oxide, confirming the successful construction of the heterojunction. Scanning electron microscopy observation shows that the fibers have a hollow tubular structure with uniform diameter, which facilitates rapid gas diffusion.
[0011] The present invention further provides a method for preparing a gas-sensitive element: the above-mentioned tin dioxide / indium oxide heterojunction nanofiber gas-sensitive material is mixed and ground with deionized water to form a slurry, which is then drop-coated onto an Ag-Pd interdigitated electrode and dried naturally at room temperature to obtain a gas-sensitive element.
[0012] This invention also relates to the application of the aforementioned tin dioxide / indium oxide heterojunction nanofiber gas-sensitive material in gas sensing and detection, particularly in the detection of triethylamine.
[0013] (III) Beneficial Effects Compared with the prior art, the present invention has the following beneficial effects: 1. The tin dioxide / indium oxide heterojunction nanofibers prepared by electrospinning combined with heat treatment in this invention have a unique hollow structure, large specific surface area, and abundant active sites, which are conducive to oxygen adsorption and gas diffusion, and significantly improve gas sensing performance.
[0014] 2. The optimal operating temperature of the material of this invention for triethylamine is reduced to 250°C, which is much lower than the operating temperature of pure tin dioxide material, which helps to reduce sensor power consumption and improve long-term stability.
[0015] 3. The material of this invention exhibits excellent sensitivity to 1-100 ppm triethylamine at 250℃. The response value increases significantly with increasing concentration. The response time to 5 ppm triethylamine is only 5 seconds, and the recovery time is 362 seconds, indicating rapid response recovery.
[0016] 4. The material of this invention has outstanding selectivity for triethylamine. At 250°C, its response value to 5 ppm triethylamine is much higher than that of interfering gases such as methanol, ethanol, acetone, toluene, and ammonia, making it suitable for the detection of triethylamine in complex environments. Attached Figure Description
[0017] Figure 1 The XRD diffraction pattern of the tin dioxide / indium oxide heterojunction nanofiber gas-sensitive material prepared in the embodiments of the present invention is shown below. Figure 2 This is a scanning electron microscope image of the tin dioxide / indium oxide heterojunction nanofiber gas-sensitive material prepared according to an embodiment of the present invention; Figure 3 The response curves of the tin dioxide / indium oxide heterojunction nanofiber gas-sensitive material prepared in the embodiments of the present invention to 5 ppm triethylamine at different temperatures are shown. Figure 4 The response curves of the tin dioxide / indium oxide heterojunction nanofiber gas-sensitive material prepared in the embodiments of the present invention to different concentrations of triethylamine at 250°C; Figure 5 The instantaneous resistance curves of the tin dioxide / indium oxide heterojunction nanofiber gas-sensitive material prepared in an embodiment of the present invention to different concentrations of triethylamine at 250°C; Figure 6 The response recovery time curve of the tin dioxide / indium oxide heterojunction nanofiber gas-sensitive material prepared in an embodiment of the present invention to 5 ppm triethylamine at 250°C is shown. Figure 7This is a comparative graph showing the selectivity of the tin dioxide / indium oxide heterojunction nanofiber gas-sensitive material prepared in the embodiments of the present invention to 5 ppm triethylamine and five interfering gases at 250°C. Detailed Implementation
[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. Those skilled in the art should understand that the following embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.
[0019] Example 1: Preparation of Tin Dioxide / Indium Oxide Heterojunction Nanofiber Gas Sensing Material (1) Preparation of mixed solvent: Take 6 mL of N,N-dimethylformamide, 3 mL of anhydrous ethanol and 1 mL of glacial acetic acid, mix them and stir at 500 r / min to obtain a uniform mixed solution.
[0020] (2) Preparation of spinning solution: Weigh stannous chloride and indium nitrate to make the tin-indium molar ratio 4:1, add them to the above mixed solution and stir to dissolve; then add 1.5g of polyvinylpyrrolidone and stir for 6h under magnetic stirring at 500r / min to obtain a homogeneous spinning solution.
[0021] (3) Electrospinning: The spinning solution is drawn into a plastic syringe, a needle is installed, and the syringe is fixed to the electrospinning machine. After setting the parameters, spinning is performed, and white composite fiber nonwoven fabric is collected.
[0022] (4) Heat treatment: The composite fiber nonwoven fabric is heated to 600℃ in air at 2℃ / min, kept at the temperature for 1h, and then naturally cooled to room temperature to obtain tin dioxide / indium oxide heterojunction nanofibers.
[0023] Material characterization X-ray diffraction analysis was performed on the prepared tin dioxide / indium oxide heterostructure nanofibers, and the results are as follows: Figure 1 As shown in the figure, the diffraction peaks correspond to the tin dioxide standard card JCPDS 41-1445 and the indium oxide standard card JCPDS 06-0416, respectively, indicating that the composite material contains both tin dioxide and indium oxide crystalline phases and no other impurity peaks.
[0024] Scanning electron microscopy observation ( Figure 2 The data shows that the fibers have a hollow tubular structure, with the tube walls composed of tightly packed nanoparticles, and the fibers interwoven to form a three-dimensional network. This hollow structure facilitates the rapid diffusion of gas into the material's interior, improving sensing performance.
[0025] Fabrication and testing of gas-sensitive elements Weigh 15 mg of the above-mentioned tin dioxide / indium oxide heterojunction nanofibers, place them in an agate mortar, add 2 mL of deionized water, and grind them into a uniform slurry. Use a dropper to draw up the slurry and drop it onto a clean Ag-Pd interdigitated electrode. After drying naturally at room temperature, place it in a vacuum drying oven at 60℃ for 12 h to obtain a gas-sensitive element.
[0026] The gas-sensing performance of the element was evaluated on a gas-sensitive testing system using a static gas mixing method. Before testing, the element was aged at 200℃ for 24 hours on an aging bench to improve stability. During testing, a certain amount of the test gas was injected into the test chamber, and the change in element resistance was recorded. Sensitivity was defined as the ratio of the element's resistance Ra in air to its resistance Rg in the target gas. Response time was the time required for the resistance change to reach 90% of the total change, and recovery time was the time required for the resistance to recover to 90% of its initial value.
[0027] Gas Sensing Performance Results Figure 3 The response curves of the component to 5 ppm triethylamine at different operating temperatures are shown. It can be seen that the response value first increases and then decreases with increasing temperature, reaching a maximum value at 250℃. Therefore, the optimal operating temperature is determined to be 250℃.
[0028] Figure 4 and Figure 5 The figures show the response curves and instantaneous resistance curves of the component at 250℃ to different concentrations of triethylamine. As the triethylamine concentration increases, the response value increases monotonically, while the resistance decreases rapidly upon contact with triethylamine.
[0029] Figure 6 The image shows the response and recovery curves of the component at 250℃ to 5 ppm triethylamine. The response time is approximately 5 s, and the recovery time is approximately 362 s, indicating that the material has a rapid response and recovery capability.
[0030] Figure 7 The response of the element to 5 ppm triethylamine and 5 ppm methanol, ethanol, acetone, toluene, and ammonia at 250℃ is compared. It is evident that the element's response to triethylamine is significantly higher than that to the other interfering gases, demonstrating excellent selectivity.
[0031] In summary, the tin dioxide / indium oxide heterojunction nanofiber gas-sensitive material provided by this invention exhibits high sensitivity, rapid response recovery, and good selectivity for triethylamine at relatively low operating temperatures, and is expected to be used for real-time monitoring of triethylamine.
[0032] This specific embodiment is for illustrative purposes only and is not intended to limit the scope of the invention. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the invention; therefore, all equivalent technical solutions also fall within the protection scope of this invention.
Claims
1. A method for preparing a tin dioxide / indium oxide heterojunction nanofiber gas-sensitive material, characterized in that, Using stannous chloride and indium nitrate as raw materials, a ternary mixed solution of N,N-dimethylformamide, anhydrous ethanol and glacial acetic acid as solvent, and polyvinylpyrrolidone as polymer template, composite fibers were obtained by electrospinning and then subjected to heat treatment in an air atmosphere to obtain a hollow tin dioxide / indium oxide heterojunction nanofiber gas-sensitive material composed of tin dioxide and indium oxide particles.
2. The method for preparing tin dioxide / indium oxide heterojunction nanofiber gas-sensitive material according to claim 1, characterized in that, Includes the following steps: S1. Mix N,N-dimethylformamide, anhydrous ethanol and glacial acetic acid to obtain a mixed solution; S2. Add stannous chloride and indium nitrate to the mixed solution, stir until homogeneous, then add polyvinylpyrrolidone and continue stirring until a uniform spinning solution is formed; S3. The spinning solution is loaded into a syringe and electrospinned to obtain a composite fiber nonwoven fabric; S4. The composite fiber nonwoven fabric is heat-treated in an air atmosphere to remove polyvinylpyrrolidone and crystallize stannous chloride and indium nitrate into tin dioxide and indium oxide, forming the hollow tin dioxide / indium oxide heterojunction nanofibers.
3. The method for preparing tin dioxide / indium oxide heterojunction nanofiber gas-sensitive material according to claim 2, characterized in that, In step S1, the volume ratio of N,N-dimethylformamide, anhydrous ethanol, and glacial acetic acid is 6:3:1, and the stirring rate is 500 r / min.
4. The method for preparing tin dioxide / indium oxide heterojunction nanofiber gas-sensitive material according to claim 2, characterized in that, In step S2, the molar ratio of stannous chloride to indium nitrate is 4:1, and the mixture is magnetically stirred for 4-8 hours at a stirring rate of 500 r / min.
5. The method for preparing tin dioxide / indium oxide heterojunction nanofiber gas-sensitive material according to claim 2, characterized in that, In step S3, the spinning solution is loaded into a syringe, a needle is installed, parameters are set, and electrospinning is performed to obtain a composite fiber nonwoven fabric.
6. The method for preparing tin dioxide / indium oxide heterojunction nanofiber gas-sensitive material according to claim 2, characterized in that, In step S4, the heat treatment process is as follows: calcination at 600℃ for 1 hour at a heating rate of 2℃ / min.
7. A tin dioxide / indium oxide heterojunction nanofiber gas-sensitive material, characterized in that, It is prepared by the method described in any one of claims 1-6.
8. A method for preparing a gas-sensitive element, characterized in that, The tin dioxide / indium oxide heterojunction nanofiber gas-sensitive material of claim 7 is mixed with deionized water to form a slurry, and then the slurry is drop-coated onto an Ag-Pd electrode and dried at room temperature to obtain a gas-sensitive element.
9. The method for preparing a gas-sensitive element according to claim 8, characterized in that, The tin dioxide / indium oxide heterojunction nanofiber gas-sensitive material was placed in an agate mortar, and deionized water was added to grind it into a slurry. The slurry was then dropped onto the Ag-Pd electrode using a dropper.
10. An application of a tin dioxide / indium oxide heterojunction nanofiber gas-sensitive material, characterized in that, The tin dioxide / indium oxide heterojunction nanofiber gas-sensitive material of claim 7 or the gas-sensitive element prepared by the method of claim 8 or 9 was used to detect triethylamine at 250°C.