Gas sensitive material based on SnO2 nano material, preparation method and application

Abstract

The invention relates to the technical field of gas-sensitive material preparation, in particular to a gas-sensitive material based on a SnO2 nano material, a preparation method and application, stannous chloride dehydrate and a precious metal acid salt ethanol solution are used for preparing a spinning solution, then the spinning solution is prepared into nano fibers in an electrostatic spinning mode, and finally the nano fibers are calcined to obtain the gas-sensitive material based on the SnO2 nano material. The noble metal doped nanofiber gas sensitive material is obtained, and noble metal doping under an electrostatic spinning process is realized; the prepared gas sensitive material has the characteristics of high specific surface area, porous structure, high sensitivity, selectivity, stability and the like, a new solution is provided for development of high-performance gas sensitive sensors, and the problems of low sensitivity and slow response speed of gas sensors in the prior art are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of gas-sensitive material preparation, and in particular to a gas-sensitive material based on SnO2 nanomaterials, a preparation method and an application thereof. Background Art

[0002] With the rapid development of the new energy industry, batteries and other energy storage devices are widely used in electric vehicles, energy storage power stations, and other fields. However, when batteries age or experience thermal runaway, they release flammable gases such as H₂, CO, and CH₄, which are key triggers of explosion accidents. Research has shown that when lead-acid batteries age, hydrogen release concentrations can reach 1,000-10,000 ppm (0.1%-1% by volume) within a sealed electric vehicle. In poorly ventilated areas such as the battery compartment or under the seat, concentrations can rapidly accumulate to 10%-25% of the lower explosive limit (LEL = 4% by volume, or 40,000 ppm) (4,000-10,000 ppm), posing a high risk of explosion. When lithium-ion batteries experience thermal runaway, hydrogen release is relatively low (typically <2,000 ppm), but is accompanied by the release of other flammable gases (such as CO and CH₄), further exacerbating safety risks. Gas sensors can monitor the composition and concentration of gases within battery energy storage systems in real time. When the battery has abnormal conditions such as overheating, short circuit, etc., which release flammable gases, the sensor can quickly capture the changes in these flammable gases, thereby issuing an early warning before serious accidents such as thermal runaway occur. Maintenance personnel can take timely measures to effectively prevent accidents.

[0003] SnO2, an n-type semiconductor oxide, offers significant advantages as an ideal gas-sensing material for semiconductor gas sensors due to its abundant surface oxygen vacancies and unique electrical properties. However, pure SnO2 exhibits insufficient response to low-concentration gases, leading to widespread issues with existing gas sensors, such as low response, slow response speed, and poor stability, making them difficult to meet the requirements for high-precision early warning systems. Therefore, the development of highly sensitive, fast-response gas sensors is crucial for real-time monitoring of battery aging. Summary of the Invention

[0004] In response to the problems of low sensitivity and slow response speed of gas sensors in the prior art, the present invention provides a gas-sensitive material based on SnO2 nanomaterials, a preparation method and application thereof.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: The present invention provides a method for preparing a gas-sensitive material based on SnO2 nanomaterials, comprising: placing stannous chloride dihydrate in a noble metal salt ethanol solution and mixing the mixture to obtain a spinning solution; The spinning solution is made into nanofibers by electrospinning; The nanofibers are calcined to obtain a gas-sensitive material based on SnO2 nanomaterials.

[0006] Alternatively, the method of mixing stannous chloride dihydrate with a noble metal salt ethanol solution to obtain a spinning solution is as follows: mixing stannous chloride dihydrate with ethanol to obtain a mixed solution; The mixed slurry is mixed with the noble metal salt ethanol solution to obtain a spinning solution.

[0007] Optionally, the mass concentration of stannous chloride dihydrate in the mixed solution is 90-110 g / L.

[0008] Optionally, the volume ratio of the mixed slurry to the noble metal salt ethanol solution is 1:(1-5).

[0009] Optionally, the mass concentration of the noble metal salt in the noble metal salt ethanol solution is 0.5 to 2 g / L.

[0010] Optionally, the noble metal salt ethanol solution is a chloroplatinic acid ethanol solution.

[0011] Optionally, the voltage of the electrospinning is 10-15 kV.

[0012] Optionally, the nanofibers are calcined at 480° C. to 520° C. for 1.5 to 3 hours.

[0013] A gas-sensitive material based on SnO2 nanomaterial is prepared using the above preparation method.

[0014] For example, the application of gas-sensitive materials based on SnO2 nanomaterials in gas sensors or battery thermal runaway warning.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a method for preparing a gas-sensitive material based on SnO2 nanomaterials. The method comprises the following steps: preparing a spinning solution by using stannous chloride dihydrate and an ethanol solution of a noble metal salt, then forming the spinning solution into nanofibers by electrospinning, and finally calcining the spinning solution to obtain a nanofiber gas-sensitive material doped with a noble metal, thereby realizing the noble metal doping under the electrospinning process; the electrospinning technology can prepare nanofibers with a high specific surface area, significantly increasing the gas diffusion path and adsorption sites, which is conducive to improving the gas adsorption and reaction ability of the gas-sensitive material to gas, thereby enhancing its gas-sensing performance; the noble metal is uniformly doped in the SnO2 fiber in the form of nanoparticles, and its catalytic activity can effectively promote the dissociation of hydrogen molecules into active H +, and accelerate the reduction reaction of oxygen ions on the SnO2 surface (SnO2+H2→SnO+H2O), thereby enhancing the electron transfer efficiency and improving the resistance response value. The method is simple and easy to operate, and can effectively regulate the doping of precious metals to optimize the performance of gas-sensitive materials. In addition, electrospinning technology has good repeatability and can prepare nanofibers with relatively consistent morphology and structure, which is beneficial to ensure the stability and reliability of the performance of gas-sensitive materials.

[0016] When preparing the spinning solution, stannous chloride dihydrate is mixed with ethanol. Stannous chloride dihydrate is a common inorganic compound that is relatively cheap and easy to obtain. Stannous chloride dihydrate is mixed and dispersed with ethanol so that the stannous chloride dihydrate is evenly heated during the subsequent calcination treatment, uniformly regulating the morphology and structure of SnO2, optimizing the crystallinity of SnO2 nanofibers, and preparing SnO2 fibers with consistent size and morphology.

[0017] The setting of the amount of stannous chloride dihydrate in the spinning solution not only ensures that the viscosity of the spinning solution is moderate, but also has an appropriate concentration that helps to form structurally stable nanofibers, reduces structural damage and performance degradation during high-temperature treatment or long-term use, and improves the reliability and service life of the gas-sensitive material.

[0018] The mass concentration of the noble metal salt in the ethanolic solution is 0.5 to 2 g / L, and the ethanolic solution is a chloroplatinic acid solution. Ethanol, as a solvent, has good solubility, enabling the chloroplatinic acid to be evenly dispersed in the solution. During the electrospinning process, the chloroplatinic acid can be evenly distributed on the surface or within the nanofibers, forming a uniform doping structure and avoiding unstable performance caused by localized excessive or insufficient concentrations.

[0019] The electrospinning voltage is 10 to 15 kV. This range provides a stable electric field strength, ensuring that the spinning solution forms a uniform Taylor cone and a stable jet at the spinneret. This prevents splashing of the spinning solution due to excessive electric field force and prevents jet breakage due to insufficient electric field force, thereby improving the continuity and controllability of the spinning process and producing nanofibers with uniform diameter and regular morphology.

[0020] The nanofibers are calcined at 480°C to 520°C for 1.5 to 3 hours. Within the temperature range of 480°C to 520°C, stannous chloride dihydrate is oxidatively decomposed into SnO2, hydrogen chloride gas, and water vapor. Furthermore, calcination under these temperature conditions enables the SnO2 fibers to complete the transformation from an amorphous or low-crystalline state to a stable rutile phase, forming a highly crystalline crystal structure. Furthermore, Pt and SnO2 form a stable heterojunction interface, inhibiting material agglomeration and ensuring the morphological stability and specific surface area of the nanofibers. The continuous structure of the nanofibers and the anchoring effect of Pt enhance the mechanical stability of the gas-sensitive material and improve cyclic stability.

[0021] A gas-sensitive material based on SnO2 nanomaterials is prepared using the above-mentioned preparation method. This gas-sensitive material has a high specific surface area and a rich microporous / mesoporous structure, providing a large number of adsorption and reaction active sites for gas molecules, significantly improving the gas-sensitive material's adsorption capacity for the target gas and enhancing the sensitivity of the gas-sensitive response. At the same time, the porous structure of the nanofibers provides efficient diffusion channels for gas molecules, shortening the transmission time of gas molecules within the material, enabling the gas-sensitive material to quickly respond to changes in gas concentration. This gas-sensitive material, combining the advantages of high specific surface area, porous structure, high crystallinity, and precious metal doping, significantly improves gas-sensing performance (sensitivity, selectivity, stability, etc.). It also has the advantages of a controllable preparation process, low cost, and environmental friendliness. It has broad application prospects in environmental monitoring, industrial safety, medical diagnosis, and other fields, providing a new solution for the development of high-performance gas sensors.

[0022] For example, the application of SnO2 nanomaterial-based gas sensors in gas sensors or battery thermal runaway warning systems. Gas sensors made with this gas-sensitive material are characterized by high sensitivity, rapid response, and long service life. They can provide early monitoring and early warning for battery thermal runaway, provide reliable data support for battery management systems, and can operate stably and long-term in complex battery operating environments, ensuring the reliability of thermal runaway warning systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The figure is a schematic flow chart of a method for preparing a gas-sensitive material based on SnO2 nanomaterials according to the present invention.

[0024] Figure 2 This is the XRD pattern of the gas-sensitive material prepared in Example 1 of the present invention.

[0025] Figure 3 This is a comparison chart of the gas sensitivity tests of Examples 1-5 of the present invention.

[0026] Figure 4This is a response change diagram of the gas-sensitive material prepared in Example 3 of the present invention at a temperature of 300°C to 400°C.

[0027] Figure 5 This is a graph showing the response value changes of the gas-sensitive material prepared in Example 3 of the present invention at 300°C under different hydrogen concentration conditions. DETAILED DESCRIPTION

[0028] To facilitate understanding of the features and effects of the present invention by those skilled in the art, the following provides a general description and definition of the terms and expressions used in the specification and claims. Unless otherwise indicated, all technical and scientific terms used herein have the ordinary meanings as understood by those skilled in the art regarding the present invention. In the event of conflict, the definitions in this specification shall prevail.

[0029] The theories or mechanisms described and disclosed herein, whether correct or incorrect, should not limit the scope of the present invention in any way, that is, the present invention can be implemented without being limited by any specific theory or mechanism.

[0030] All features, such as values, amounts, contents, and concentrations, described herein as numerical ranges or percentage ranges are provided for simplicity and convenience only. Accordingly, the description of numerical ranges or percentage ranges should be considered to include and specifically disclose all possible subranges and individual values within the range (including integers and fractions).

[0031] In this document, unless otherwise specified, “include,” “including,” “contains,” “has” or similar terms cover the meanings of “consisting of” and “mainly consisting of,” for example, “A includes a” covers the meanings of “A includes a and other” and “A only includes a.”

[0032] In this document, for the sake of brevity, not all possible combinations of the various technical features in each embodiment or example are described. Therefore, as long as there are no contradictions in the combination of these technical features, the various technical features in each embodiment or example can be combined in any way, and all possible combinations should be considered to be within the scope of this specification.

[0033] Below in conjunction with specific embodiment, further set forth the present invention.Should be understood that these embodiments are only used to illustrate the present invention and are not used in limiting the scope of the present invention.In addition, should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall equally within the scope limited by the appended claims of the application.

[0034] The following examples were prepared using conventional instruments and equipment in the art. Experimental methods in the following examples, where specific conditions are not specified, were generally performed under conventional conditions or according to the conditions recommended by the manufacturer. The various raw materials used in the following examples, unless otherwise specified, were conventional commercially available products, with specifications conventional in the art. In the present specification and the following examples, unless otherwise specified, "%" indicates percentage by weight, "part" indicates parts by weight, and "ratio" indicates weight ratio.

[0035] The present invention will be further described in detail below with reference to specific embodiments, which are intended to explain the present invention rather than to limit it.

[0036] See also Figure 1 The present invention discloses a method for preparing a gas-sensitive material based on SnO2 nanomaterials, comprising: S1: Stannous chloride dihydrate is placed in a noble metal salt ethanol solution and mixed to obtain a spinning solution, specifically: Mixing stannous chloride dihydrate with ethanol to obtain a mixed solution; the mass concentration of stannous chloride dihydrate in the mixed solution is 90-110 g / L; The mixed slurry is mixed with a noble metal salt ethanol solution in a volume ratio of 1:(1-5) to obtain a spinning solution; S2: The spinning solution is made into nanofibers by electrospinning, specifically: The spinning solution is spun at a voltage of 10 to 15 kV, and the nanofibers are collected.

[0037] S3: calcining the nanofibers to obtain a gas-sensitive material based on SnO2 nanomaterials. Specifically, calcining the collected nanofibers at 480°C to 520°C for 1.5 to 3 hours to obtain Pt-doped SnO2 nanofibers (Pt mass content is 1% to 5%), i.e., a gas-sensitive material based on SnO2 nanomaterials.

[0038] Example 1 100 mg of stannous chloride dihydrate (SnCl2·2H2O) was dissolved in 100 μL of ethanol solution and then added to 100 μL of a 0.5 mg / mL chloroplatinic acid ethanol solution. After ultrasonic mixing, the mixture was spun at 10 kV. The nanofibers were collected and calcined in a tube furnace at 500°C for 2 hours to obtain Pt-doped SnO2 nanofibers (Pt content: 1%).

[0039] Example 2 100mg of stannous chloride dihydrate (SnCl2·2H2O) was dissolved in 100ul of ethanol solution and then added to 100μL of 1mg / mL chloroplatinic acid ethanol solution. After ultrasonic mixing, the mixture was spun at 10kV. The nanofibers were collected and calcined in a tube furnace at 500°C for 2h to obtain Pt-doped SnO2 nanofibers (Pt doping percentage was 2%). Example 3 100 mg of stannous chloride dihydrate (SnCl2·2H2O) was dissolved in 100 μL of ethanol and added to 100 μL of a 2 mg / mL chloroplatinic acid ethanol solution. After ultrasonic mixing, the mixture was spun at 10 kV. The nanofibers were collected and calcined in a tube furnace at 500°C for 2 hours to obtain Pt-doped SnO2 nanofibers (Pt doping percentage: 3% by mass).

[0040] Example 4 100 mg of stannous chloride dihydrate (SnCl2·2H2O) was dissolved in 100 μl of ethanol and added to 200 μL of a 2 mg / mL chloroplatinic acid ethanol solution. After ultrasonic mixing, the mixture was spun at 10 kV. The nanofibers were collected and calcined in a tube furnace at 500°C for 2 hours to obtain Pt-doped SnO2 nanofibers (Pt doping percentage: 4%).

[0041] Example 5 100 mg of stannous chloride dihydrate (SnCl2·2H2O) was dissolved in 100 μL of ethanol solution and added to 500 μL of a 2 mg / mL chloroplatinic acid ethanol solution. After ultrasonic mixing, the mixture was spun at 10 kV. The nanofibers were collected and calcined in a tube furnace at 500°C for 2 hours to obtain Pt-doped SnO2 nanofibers (Pt doping percentage: 5%).

[0042] Example 6 100 mg of stannous chloride dihydrate (SnCl2·2H2O) was dissolved in 100 μL of ethanol solution and then added to 500 μL of a 2 mg / mL chloroplatinic acid ethanol solution. After ultrasonic mixing, the mixture was spun at 15 kV. The nanofibers were collected and calcined in a tube furnace at 480°C for 3 hours to obtain Pt-doped SnO2 nanofibers (Pt doping percentage: 4%).

[0043] Example 7 100 mg of stannous chloride dihydrate (SnCl2·2H2O) was dissolved in 100 μl of ethanol solution and then added to 500 μL of a 2 mg / mL chloroplatinic acid ethanol solution. After ultrasonic mixing, the mixture was spun at 13 kV. The nanofibers were collected and calcined in a tube furnace at 520°C for 1.5 hours to obtain Pt-doped SnO2 nanofibers (Pt doping percentage: 5%). To further illustrate the beneficial effects of the present invention, see Figure 2 XRD tests were performed on the gas-sensitive material prepared in Example 1. The results showed that the Pt-doped SnO2 nanofibers had a complete crystal structure, indicating effective Pt doping. The material was also of high purity. The complete structure and high purity ensured stable electron transfer and achieved a high response value. At the same time, Pt doping could effectively accelerate electron transfer and bring about a rapid response. These characteristics together maintained the stability of the material. Figure 2 The gas sensitivity test of Examples 1-5 was conducted using a CGS-4TPs system. First, the resistance change of the electrodes with different doping concentrations was measured at a temperature of 300°C and a hydrogen concentration of 1000ppm. It was found that the response values of each sample showed a trend of first increasing and then decreasing with the change of Pt doping content. The electrode prepared with a gas-sensitive material doped with 3% Pt by mass had the best effect and showed the most excellent response performance. Figure 4 , then measured the temperature variation of the electrode response value of the gas-sensitive material doped with 3% Pt at a temperature of 200℃ to 400℃. The results showed that under the condition of a hydrogen concentration of 1000ppm, the response value of the SnO2 nanofiber sample doped with 3% Pt by mass showed a trend of first increasing and then decreasing with increasing temperature. Among them, the sample showed the best response performance at a temperature of about 300℃. Figure 5 The response of an electrode made of a gas-sensitive material doped with 3% Pt by mass at 300°C under different hydrogen concentrations showed an increasing trend. Specifically, at a hydrogen concentration of around 1000 ppm, the sample's resistance reached its maximum and its response reached its minimum. Therefore, the hydrogen concentration alarm threshold can be set at 1000 ppm. This indicates that, at a hydrogen concentration of 1000 ppm, the gas-sensitive material doped with 3% Pt by mass exhibited an optimal response of 218 at 300°C, a response time of 8 seconds, and a recovery time of 18 seconds. Finally, under optimal conditions, 10 cycles of testing revealed a performance degradation rate of less than 5%, demonstrating excellent stability.

[0044] A gas-sensitive material based on SnO2 nanomaterials is prepared using the above-mentioned preparation method. This gas-sensitive material has a high specific surface area and a rich microporous / mesoporous structure, providing a large number of adsorption and reaction active sites for gas molecules, significantly improving the gas-sensitive material's adsorption capacity for the target gas and enhancing the sensitivity of the gas-sensitive response. At the same time, the porous structure of the nanofibers provides efficient diffusion channels for gas molecules, shortening the transmission time of gas molecules within the material, enabling the gas-sensitive material to quickly respond to changes in gas concentration. This gas-sensitive material, combining the advantages of high specific surface area, porous structure, high crystallinity, and precious metal doping, significantly improves gas-sensing performance (sensitivity, selectivity, stability, etc.). It also has the advantages of a controllable preparation process, low cost, and environmental friendliness. It has broad application prospects in environmental monitoring, industrial safety, medical diagnosis, and other fields, providing a new solution for the development of high-performance gas sensors.

[0045] For example, the application of SnO2 nanomaterial-based gas sensors in gas sensors or battery thermal runaway warning systems. Gas sensors made with this gas-sensitive material are characterized by high sensitivity, rapid response, and long service life. They can provide early monitoring and early warning for battery thermal runaway, provide reliable data support for battery management systems, and can operate stably and long-term in complex battery operating environments, ensuring the reliability of thermal runaway warning systems.

[0046] For this application, we selected a thin-film metal-oxide-semiconductor (MOS) gas sensor, taking into account factors such as the material's optimal response temperature, heating method, and signal stability. The sensor's thin-film structure allows for the integration of a microheater, maintaining an operating temperature of around 300°C, meeting high-temperature requirements. Furthermore, the thin-film process effectively supports the loading of SnO2 nanomaterials, preserving their porosity and activity. The ceramic substrate offers high-temperature resistance (300°C) and excellent insulation. Furthermore, the interdigitated electrode structure maximizes the contact area between the sensitive material and the electrodes, improving signal sensitivity and response speed. Based on the experimental data, a supporting gas detection and alarm system can be designed, including an analog-to-digital conversion module, a decoding module, a concentration display module, and an alarm module. When used in battery thermal runaway warning systems, the system detects gas concentrations through changes in the resistance of a gas sensor resistor. An analog-to-digital converter (ADC) converts the analog signal into a digital signal, which is then displayed using a binary-coded decimal (BCD) decoder and a seven-segment display. A comparator and threshold settings are used to implement an alarm. When the gas concentration exceeds the set threshold, a light-emitting diode (LED) and a buzzer sound a simultaneous alarm, providing a safety warning of battery aging. During operation, the gas sensor resistor change is converted into a digital signal using a high-precision ADC, which, combined with a threshold comparator, triggers a real-time alarm (1000 ppm H2). The low-impedance matching design of the circuit and sensor materials reduces signal noise, ensuring detection sensitivity and stability.

[0047] In summary, the present invention provides a gas-sensitive material based on SnO2 nanomaterials, a preparation method and an application thereof. The spinning solution is prepared by using stannous chloride dihydrate and an ethanol solution of a noble metal salt, and then the spinning solution is made into nanofibers by electrospinning. Finally, the spinning solution is calcined to obtain a nanofiber gas-sensitive material doped with noble metals, thereby realizing the noble metal doping under the electrospinning process. The prepared gas-sensitive material has the characteristics of high specific surface area, porous structure, high sensitivity, selectivity, stability, etc., and provides a new solution for the development of high-performance gas sensors.

[0048] The above description is merely a preferred embodiment of the present invention and is not intended to impose any limitation on the technical solution of the present invention. Those skilled in the art should understand that, without departing from the spirit and principles of the present invention, the technical solution can also be subjected to several simple modifications and replacements, and these modifications and replacements are also within the scope of protection covered by the claims.

Claims

1. A method for preparing a gas-sensitive material based on SnO2 nanomaterials, characterized in that: include: placing stannous chloride dihydrate in a noble metal salt ethanol solution and mixing the mixture to obtain a spinning solution; The spinning solution is made into nanofibers by electrospinning; The nanofibers are calcined to obtain a gas-sensitive material based on SnO2 nanomaterials.

2. The method for preparing a gas-sensitive material based on SnO2 nanomaterial according to claim 1, characterized in that: The method of placing stannous chloride dihydrate in a noble metal salt ethanol solution and mixing the mixture to obtain a spinning solution is as follows: mixing stannous chloride dihydrate with ethanol to obtain a mixed solution; The mixed slurry is mixed with the noble metal salt ethanol solution to obtain a spinning solution.

3. The method for preparing a gas-sensitive material based on SnO2 nanomaterial according to claim 2, characterized in that: The mass concentration of stannous chloride dihydrate in the mixed solution is 90-110 g / L.

4. The method for preparing a gas-sensitive material based on SnO2 nanomaterial according to claim 2, characterized in that: The volume ratio of the mixed slurry to the noble metal salt ethanol solution is 1:(1-5).

5. The method for preparing a gas-sensitive material based on SnO2 nanomaterial according to claim 1, characterized in that: The mass concentration of the noble metal salt in the noble metal salt ethanol solution is 0.5-2 g / L.

6. The method for preparing a gas-sensitive material based on SnO2 nanomaterial according to claim 1, characterized in that: The noble metal salt ethanol solution is chloroplatinic acid ethanol solution.

7. The method for preparing a gas-sensitive material based on SnO2 nanomaterial according to claim 1, characterized in that: The voltage of the electrostatic spinning is 10-15 kV.

8. The method for preparing a gas-sensitive material based on SnO2 nanomaterial according to claim 1, characterized in that: The conditions for calcining the nanofibers are: calcining at 480° C. to 520° C. for 1.5 to 3 hours.

9. A gas-sensitive material based on SnO2 nanomaterial, characterized in that: Prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the gas-sensitive material based on SnO2 nanomaterials as claimed in claim 9 in gas sensors or battery thermal runaway warning.

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