SnTe material, fabrication process and application for nitrogen dioxide gas sensors
Small-sized SnTe nanomaterials were prepared by a solvothermal method for use in nitrogen dioxide sensors, which solved the problem of high-temperature operation of traditional sensors and achieved high-performance nitrogen dioxide detection at room temperature, making them suitable for portable and wearable devices.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- DALIAN UNIV OF TECH
- Filing Date
- 2026-03-04
- Publication Date
- 2026-05-26
AI Technical Summary
Existing metal oxide-based nitrogen dioxide sensors require high temperatures to operate, resulting in high energy consumption and short lifespan, which limits their application in portable and wearable devices. Furthermore, existing room temperature sensors are not performing well.
SnTe nanomaterials were synthesized using a solvothermal method. Small-sized SnTe nanostructures were prepared by controlling the nucleation process and used as a nitrogen dioxide gas sensor at room temperature. The detection of nitrogen dioxide was achieved by changing the carrier concentration through electron transfer between gas molecules and the semiconductor surface.
This invention achieves high sensitivity, low detection limit, and fast response for nitrogen dioxide detection at room temperature. The sensor exhibits good stability, is suitable for portable and wearable devices, and has a simple and low-cost manufacturing process, making it a promising candidate for industrial applications.
Smart Images
Figure CN122084698A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of electronic components technology, and relates to a SnTe material, its preparation process, and its application for a nitrogen dioxide gas sensor. Background Technology
[0002] Nitrogen oxides (NO) X Nitrogen dioxide (NO2) is a significant component of atmospheric pollutants, exerting profound and serious impacts on the environment and human health. A key precursor to environmental problems such as acid rain and photochemical smog, NO2 can enter the human body through the respiratory tract, causing a range of respiratory diseases such as bronchitis, asthma, and emphysema, and may even increase the risk of cardiovascular diseases. As a final product of numerous gaseous reactions in the atmosphere, NO2 exhibits dynamic concentration changes and a long persistence. Given its severe hazards and characteristics, accurate, sensitive, and rapid real-time detection is crucial.
[0003] Among numerous gas detection technologies, resistive semiconductor sensors dominate research and application due to their outstanding sensitivity and rapid response characteristics. Research on sensors based on metal oxide substrates is currently quite in-depth, and their fabrication techniques are more mature. Furthermore, they are widely used due to their lower production costs and reliable quality. However, metal oxide-based semiconductor sensors typically require operating temperatures exceeding 200°C to provide the activation energy for gas adsorption and surface reactions. High-temperature operating conditions not only increase energy consumption but also shorten the lifespan of the components, limiting their application in portable and wearable devices. Therefore, developing a high-performance nitrogen dioxide sensor that can operate at room temperature is crucial.
[0004] SnTe, as a member of transition metal chalcogenides (TMDs), possesses a narrow band gap and good chemical stability, enabling it to interact effectively with gas molecules and thereby alter its electrical properties, thus providing possibilities for gas detection. Furthermore, its sensing mechanism does not rely on thermally activated surface oxygen species reactions, overcoming the shortcomings of traditional oxide semiconductors in room temperature detection. Summary of the Invention
[0005] The purpose of this invention is to further explore the gap in gas detection using semiconductor sensors at room temperature. It provides a SnTe material with good selectivity, high sensitivity, strong stability and low detection limit using a simple preparation method, which makes it possible to apply nitrogen dioxide sensors in portable wearable devices.
[0006] The technical solution of the present invention: A SnTe material for a nitrogen dioxide gas sensor is synthesized by a solvothermal method. The nitrogen dioxide gas sensor for testing mainly consists of a gas-sensitive material and a gold interdigitated electrode. The gas-sensitive material is coated on the surface of the gold interdigitated electrode with a coating thickness of approximately 15 μm to 75 μm. The gas-sensitive material is SnTe.
[0007] The microstructure of the SnTe material has a diameter between 200 nm and 400 nm.
[0008] The gold interdigitated electrode is an alumina substrate with a pure gold electrode on the front side, with 3 to 10 pairs of interdigitated fingers and a substrate thickness of 2 to 5 μm.
[0009] The test of the response to nitrogen dioxide was conducted at room temperature.
[0010] A fabrication process for SnTe material used in nitrogen dioxide gas sensors includes the following steps: (1) Dissolve Te powder in ethanolamine and stir vigorously until completely dissolved to obtain a mixed solution; (2) Add SnCl2·2H2O to the mixed solution obtained in step (1) and stir vigorously until a homogeneous mixed solution is formed, controlling the molar ratio of Te powder to SnCl2·2H2O to be 1:1; (3) Prepare a 6M KOH solution, add it to the mixed solution obtained in step (2), and stir continuously for a period of time to obtain a suspension; (4) The suspension obtained in step (3) is transferred to a hydrothermal reactor lined with polytetrafluoroethylene. The hydrothermal reaction is carried out at 170~180℃ for 20~24h. The product after the hydrothermal reaction is separated by centrifuge. The separated solid product is washed repeatedly with deionized water and anhydrous ethanol. The obtained solid product is placed in a vacuum drying oven and dried at 60℃ to obtain SnTe material. (5) Place the SnTe material in a mortar, add deionized water, wet grind it to prepare a dispersion of 16~20mg / mL, then take the dispersion and coat it onto the surface of the gold interdigitated electrode, place it in a vacuum drying oven at 35℃ for 4~6h, and cool it naturally to room temperature to obtain the SnTe nanomaterial gas sensor.
[0011] Working principle of the invention: By constructing a delayed-triggered nucleation environment, the nucleation step was controlled. The pre-coordination of ethanolamine and the addition of high-concentration KOH triggered explosive nucleation in the solvent system, making it easier to synthesize smaller nanostructures during the solvothermal process. The SnTe material of this invention can be used as a resistive semiconductor NO2 gas sensor. When the semiconductor comes into contact with the target gas, electron transfer occurs between gas molecules and the semiconductor surface, causing a change in the carrier concentration of the material, which is reflected in the change in the semiconductor's resistance, thereby reflecting the type and concentration of the gas to be measured. The work function of the SnTe semiconductor material of this invention is less than the affinity of NO2 molecules for the carrier concentration in the semiconductor. Therefore, when the gas molecules adsorb onto the semiconductor surface, they will draw electrons from the material, causing a change in the carrier concentration in the material, which in turn causes a change in the conductivity of the semiconductor material. Thus, the real-time monitoring signal of the sensor can be reflected by measuring the change in resistance.
[0012] The beneficial effects of this invention are: (1) This invention provides a simple, low-cost, safe, and controllable method for preparing TMDC nanomaterials. Ethanolamine is used as both a solvent and a coordinating agent, and potassium hydroxide aqueous solution is used as a tellurium source activator to synthesize SnTe nanomaterials in one step via a solvothermal method. The raw materials used (Te powder, SnCl2·2H2O, KOH, and ethanolamine) are all common chemical reagents, readily available and inexpensive; the reaction conditions are mild (170-180℃), requiring no high temperature, high pressure, or complex equipment; the operation process is simple, and the product can be controlled by adjusting the order of addition, the amount of KOH, and the hydrothermal temperature / time. This invention avoids the use of toxic reagents (such as hydrazine hydrate), exhibiting significant operational safety and environmental friendliness. It is a semiconductor nanomaterial preparation method with low capital investment and a simple process flow, possessing good prospects for industrial application. (2) The SnTe nanomaterials prepared by this invention have a smaller nanosize. A large number of small-sized nanomaterials can effectively increase the full contact between the material and gas molecules and improve the residence rate of gas molecules on the surface of the nanomaterials.
[0013] (3) The present invention exhibits good selectivity and stable gas detection performance for NO2, with a detection limit as low as ppb, and the response recovery time of the sensor is greatly shortened. In addition, the sensor can exhibit good sensing performance at room temperature, effectively mitigating the aging and damage caused by the material participating in the reaction for a long time at high temperature.
[0014] (4) This invention provides a new research approach for expanding the application of TMDC materials in the field of gas sensing. Using SnTe as a model material, this invention systematically studies the effects of process parameters such as feeding sequence, alkali dosage, and reaction temperature / time on the products and gas sensing performance. This research approach can be extended to other TMDC material systems, providing a useful reference for the controllable preparation and performance optimization of related nanomaterials. Attached Figure Description
[0015] Figure 1 This is a scanning electron microscope image of the SnTe nanomaterial of this invention.
[0016] Figure 2 The image shows the response curve of the SnTe nanomaterial gas sensor of this invention to 1 ppm nitrogen dioxide at room temperature.
[0017] Figure 3 This is a response curve of the SnTe nanomaterial gas sensor of the present invention to nitrogen dioxide at room temperature ranging from 0.075 ppm to 1 ppm. Detailed Implementation
[0018] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and technical solutions.
[0019] Example 1 (1) Dissolve 1 mmol of tellurium powder (Te) in 30 ml of ethanolamine and stir at room temperature for 30 minutes until the solution becomes homogeneous.
[0020] (2) Add 1 mmol of stannous chloride dihydrate (SnCl2·2H2O) to the solution obtained in step (1) and stir vigorously for 30 minutes.
[0021] (3) Take 5 ml of the prepared 6M potassium hydroxide (KOH) aqueous solution and add it to the solution obtained in step (2). Stir vigorously until the solution turns gray-black.
[0022] (4) The suspension obtained in step (3) was transferred to a hydrothermal reactor lined with polytetrafluoroethylene. The hydrothermal reaction was carried out at 170°C for 24 hours. The product obtained after the hydrothermal reaction was then centrifuged at 3500 rpm for 30 minutes to separate the solid and liquid components. The obtained solid product was washed multiple times with deionized water and ethanol. The obtained solid product was placed in a vacuum drying oven and dried at 60°C for 6 hours to obtain SnTe nanomaterials.
[0023] (5) Grind the SnTe nanomaterial into powder, then disperse the ground SnTe nanomaterial powder in deionized water, and after grinding, process it into a dispersion of 28~30mg / ml. Then take the dispersion and apply it to the surface of the gold interdigitated electrode plate, place it in a vacuum drying oven at 35℃ for 4h, and cool it naturally to room temperature to obtain the SnTe nanomaterial gas sensor.
[0024] Example 2 Based on Example 1, the hydrothermal reaction temperature in step (4) was adjusted to 180°C, and the rest was the same as in Example 1.
[0025] Example 3 Based on Example 1, the hydrothermal reaction time in step (4) was adjusted to 20h, and the rest was the same as in Example 1.
[0026] Comparative Example 1 (1) Dissolve 1 mmol of tellurium powder (Te) in 30 ml of ethanolamine and stir at room temperature for 30 minutes until the solution becomes homogeneous.
[0027] (2) Add 1 mmol of stannous chloride dihydrate (SnCl2·2H2O) to the solution obtained in step (1) and stir vigorously for 30 minutes.
[0028] (3) The suspension obtained in step (2) was transferred to a hydrothermal reactor lined with polytetrafluoroethylene. The hydrothermal reaction was carried out at 170°C for 24 hours. The product obtained after the hydrothermal reaction was then centrifuged at 3500 rpm for 30 minutes to separate the solid and liquid components. The obtained solid product was washed multiple times with deionized water and ethanol. The obtained solid product was placed in a vacuum drying oven and dried at 60°C for 6 hours to obtain SnTe nanomaterials.
[0029] Comparative Example 2 (1) Dissolve 1 mmol of tellurium powder (Te) in 30 ml of ethanolamine and stir at room temperature for 30 minutes until the solution becomes homogeneous.
[0030] (2) Add 1 mmol of stannous chloride dihydrate (SnCl2·2H2O) to the solution obtained in step (1) and stir vigorously for 30 minutes.
[0031] (3) Take 10 ml of the prepared 6M potassium hydroxide (KOH) aqueous solution and add it to the solution obtained in step (2). Stir vigorously until the solution turns gray-black.
[0032] (4) The suspension obtained in step (3) was transferred to a hydrothermal reactor lined with polytetrafluoroethylene. The hydrothermal reaction was carried out at 170°C for 24 hours. The product obtained after the hydrothermal reaction was then centrifuged at 3500 rpm for 30 minutes to separate the solid and liquid components. The obtained solid product was washed multiple times with deionized water and ethanol. The obtained solid product was placed in a vacuum drying oven and dried at 60°C for 6 hours to obtain SnTe nanomaterials.
[0033] Analysis of Results from Examples and Comparative Examples Example 1 uses the sequence of "Te powder first dissolved in ethanolamine → SnCl2·2H2O added → KOH added last". The mechanism is that the Te powder is dispersed in solid form in the Sn-containing solution before the KOH is added. 2+ In the solution of the coordination complex, when KOH is injected, the surface of the Te particles is activated and dissolved in situ, instantly generating a high concentration of active Te species in a localized area, while Sn... 2+ The ethanolamine is released simultaneously from its strong coordination due to the addition of the alkaline aqueous solution, creating extremely high local supersaturation near the surface of the Te particles. This triggers explosive nucleation, generating a large number of fine crystal nuclei. During the subsequent hydrothermal process, Te slowly dissolves and preferentially grows on the existing nuclei, naturally achieving separation of nucleation and growth, ultimately yielding the target SnTe nanostructure. Fluctuations in solvothermal temperature and time in Examples 2 and 3 did not affect the results.
[0034] In Comparative Example 1, a hydrothermal reaction was carried out using only ethanolamine as a solvent without the addition of KOH aqueous solution. Because tellurium powder could not effectively dissolve and participate in the reaction in an alkaline environment, the product could not obtain the target SnTe phase with reduced size. This indicates that a strongly alkaline environment is crucial for the rapid activation of the tellurium and tin sources during the reaction, and is an indispensable core element of the technical solution of this invention.
[0035] In Comparative Example 2, when the amount of KOH aqueous solution was increased to 10 ml, it diluted the effect of ethanolamine on Sn. 2+ Its coordination protection capability enables some Sn 2+ It breaks away from the coordinated stable state; on the other hand, it significantly enhances the effect of the alkaline environment on Sn. 2+ The oxidation process causes some Sn to... 2+ It is oxidized to Sn before participating in the tellurization reaction. 4+ SnO2 is generated during the experiment.
Claims
1. A process for preparing SnTe material for a nitrogen dioxide gas sensor, characterized in that, The steps are as follows: (1) Dissolve Te powder in ethanolamine and stir vigorously until completely dissolved to obtain a mixed solution; (2) Add SnCl2·2H2O to the mixed solution obtained in step (1) and stir vigorously until a homogeneous mixed solution is formed, controlling the molar ratio of Te powder to SnCl2·2H2O to be 1:1; (3) Prepare a 6M KOH solution, add it to the mixed solution obtained in step (2), and stir continuously for a period of time to obtain a suspension; (4) The suspension obtained in step (3) is transferred to a hydrothermal reactor lined with polytetrafluoroethylene. The hydrothermal reaction is carried out at 170~180℃ for 20~24h. The product after the hydrothermal reaction is separated by centrifuge. The separated solid product is washed repeatedly with deionized water and anhydrous ethanol. The obtained solid product is placed in a vacuum drying oven and dried at 60℃ to obtain SnTe material. (5) Place the SnTe material in a mortar, add deionized water, wet grind it to prepare a dispersion of 16~20mg / mL, then take the dispersion and coat it onto the surface of the gold interdigitated electrode, place it in a vacuum drying oven at 35℃ for 4~6h, and cool it naturally to room temperature to obtain the SnTe nanomaterial gas sensor.
2. A SnTe material for a nitrogen dioxide gas sensor obtained by the preparation process described in claim 1, characterized in that, The SnTe material was synthesized by a solvothermal method. The nitrogen dioxide gas sensor used for testing mainly consists of a gas-sensitive material and a gold interdigitated electrode. The gas-sensitive material is coated on the surface of the gold interdigitated electrode with a coating thickness of about 15 μm to 75 μm. The gas-sensitive material is SnTe.
3. The SnTe material for a nitrogen dioxide gas sensor according to claim 2, characterized in that, The microstructure of the SnTe material has a diameter between 200 nm and 400 nm.
4. The SnTe material for a nitrogen dioxide gas sensor according to claim 2, characterized in that, The gold interdigitated electrode is an alumina substrate with a pure gold electrode on the front side, with 3 to 10 pairs of interdigitated fingers and a substrate thickness of 2 to 5 μm.
5. The SnTe material for a nitrogen dioxide gas sensor according to claim 2, characterized in that, The test for the response to nitrogen dioxide was conducted at room temperature.