An ammonia gas sensor based on SnS2 and In2S3 heterojunction, preparation process and application

Abstract

This invention belongs to the field of electronic component technology and provides an ammonia gas sensor based on a SnS2 and In2S3 heterojunction, its fabrication process, and its application. This ammonia gas sensor based on a SnS2 and In2S3 heterojunction consists of a gas-sensitive material and interdigitated electrode plates, with the gas-sensitive material coated on the surface of the interdigitated electrode plates. The gas-sensitive material is a nanomaterial formed by a composite of tin disulfide and indium trisulfide. The manufacturing process is simple, and the resulting gas-sensitive material exhibits high sensitivity and rapid response recovery to ammonia. Since the sensitive materials of traditional gas sensors are mostly metal oxides, their operating temperatures are too high, which not only increases energy consumption but also easily degrades component performance and shortens lifespan. This invention enables the gas sensor to operate at room temperature, providing a new solution for the design and fabrication of portable and wearable electronic hardware devices.

Description

Technical Field

[0001] This invention belongs to the field of electronic components technology, specifically relating to the preparation, detection method and application of a SnS2 / In2S3 ammonia gas sensor. Background Technology

[0002] With rapid industrialization, nitrogen hydrides are widely used in industrial production. Ammonia, as a typical industrial gas, is extensively used in industrial water sterilization, oil and sugar refining, and biomedicine. To avoid ammonia pollution of the atmosphere and harm to human health, real-time monitoring of ammonia in industrial production is crucial. Therefore, a gas sensor capable of detecting atmospheric ammonia concentration is essential in both production and daily life.

[0003] Currently, among the various types of gas sensors, the research and fabrication technology of metal oxide-based gas sensors is the most mature, and they are widely used due to their reliable quality and low cost. Currently, the most widely available sensors on the market are metal oxide gas sensors and solid-state electrolyte gas sensors. Both of these, as first-generation gas sensors, have attracted considerable attention, but their drawbacks are also significant. The performance of these two types of sensors is significantly affected by operating temperature and surface reaction, making it difficult for them to achieve highly sensitive performance. Typically, gas sensors using metal oxide semiconductors as sensing materials operate at temperatures between 200-500℃, requiring the installation of heating wires on the sensor element. This not only increases energy consumption but also easily degrades element performance and shortens lifespan. Furthermore, excessively high operating temperatures reduce the practicality of the manufactured gas sensors, especially for applications in portable and wearable sensor devices. To improve practicality, many researchers are dedicated to developing portable, wear-resistant, and wearable gas sensor systems, allowing for natural adaptation and flexibility in electronic hardware. Therefore, exploring new materials to achieve rapid and accurate gas detection at room temperature is crucial.

[0004] Among transition metal dichalcogenides (TMDs), SnS2 exhibits a wide bandgap, excellent photoelectric properties, superior sensing performance, and gas adsorption capacity, making it a highly sought-after material due to its high gas sensitivity, good response recovery, and low operating temperature. However, two-dimensional metal sulfides show low gas response values ​​at room temperature and suffer from baseline drift, indicating significant room for improvement in their gas-sensing performance. Considering these shortcomings, SnS2 is composited with other transition metal sulfides to obtain nanocomposite materials, thus addressing the deficiencies of single-component composites. Indium sulfide (ISS) is an n-type semiconductor material with a suitable bandgap, high chemical stability, and low toxicity, showing broad application prospects in photocatalytic dye degradation, solar cells, lithium-ion batteries, photoconductive devices, fluorescent displays, and cancer diagnosis in medicine. Therefore, the design and synthesis of gas-sensing materials composed of tin disulfide and indium trisulfide will have significant scientific and practical implications. However, to our knowledge, reports on ISS in the field of gas-sensing materials are still scarce. Therefore, in this study, we formed a heterojunction structure by attaching indium trisulfide to the surface of flower-shaped tin disulfide using a hydrothermal method, and systematically studied its microstructure and gas-sensing properties. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide an ammonia gas sensor and its detection method that have good selectivity, high sensitivity, good stability and can work stably at room temperature, thus making it possible to realize portable gas sensing devices.

[0006] The technical solution of the present invention:

[0007] An ammonia gas sensor based on SnS2 and In2S3 heterojunction is disclosed. The ammonia gas sensor mainly consists of a gas-sensitive material and an interdigitated electrode plate. The gas-sensitive material is coated on the surface of the interdigitated electrode plate with a coating thickness of 20 μm to 80 μm. The gas-sensitive material is a heterojunction composite nanomaterial of tin disulfide and indium trisulfide.

[0008] The tin disulfide and indium trisulfide heterojunction composite nanomaterial is formed by attaching indium trisulfide to the surface of flower-shaped tin disulfide using a hydrothermal method.

[0009] The interdigitated electrode plate is an alumina substrate with pure gold electrodes on the front side, with 3 to 10 pairs of interdigitated fingers and a thickness of 2 to 5 μm.

[0010] The ammonia gas sensor operates at room temperature, achieving material integration with silicon-based microelectronics.

[0011] A fabrication process for an ammonia gas sensor based on SnS2 and In2S3 heterojunctions includes the following steps:

[0012] (1) Dissolve SnCl4·5H2O and thioacetamide in isopropanol in sequence, control the molar ratio of SnCl4·5H2O and thioacetamide to be 1:4~5, and stir vigorously until completely dissolved to obtain a mixed solution.

[0013] (2) Add In2O3 nanoparticles to the mixed solution obtained in step (1), control the molar ratio of In2O3 and SnCl4·5H2O to 1:2-4, stir vigorously until the In2O3 nanoparticles are completely dispersed, and then perform ultrasonic treatment for 1-2 hours to obtain a uniform suspension.

[0014] (3) The suspension obtained in step (2) was transferred to a hydrothermal reactor lined with polytetrafluoroethylene. The hydrothermal reaction was carried out at 160-200℃ for 12-24 hours. The product after the hydrothermal reaction was then separated into solid and liquid by centrifuge. The obtained solid product was washed several times with deionized water and anhydrous ethanol. The obtained solid product was placed in a drying oven and dried at 60℃ to obtain tin disulfide and indium trisulfide heterojunction composite nanomaterials.

[0015] (4) Grind the tin disulfide and indium trisulfide heterojunction composite nanomaterials into powder, then disperse the ground tin disulfide and indium trisulfide heterojunction composite nanomaterial powder in deionized water, and sonicate it into a dispersion of 8 mg / mL to 10 mg / mL. Then take the dispersion and coat it onto the surface of the interdigitated electrode plate, place it in a drying oven at 60°C for 4 to 6 hours, and cool it naturally to room temperature to obtain the SnS2 / In2S3 nanocomposite gas sensor.

[0016] In step (2), the ultrasonic power is 240W to 260W.

[0017] The gas sensor fabricated based on SnS2 / In2S3 nanocomposite material operates at room temperature, achieving integration of the material with silicon-based microelectronic phases.

[0018] Working principle of the invention:

[0019] This invention relates to an ammonia gas sensor, a resistive semiconductor gas sensor. It primarily utilizes the change in carrier concentration caused by the redox reaction on the semiconductor surface when it comes into contact with the analyte gas, which in turn alters the semiconductor's resistance. This change reflects the type and concentration of the analyte gas. The work function of the semiconductor used in this ammonia gas sensor is greater than the affinity of ammonia gas molecules for carriers in the semiconductor. Therefore, the analyte gas molecules adsorbed on the semiconductor surface donate free electrons to the semiconductor, causing a change in carrier concentration and consequently a change in semiconductor conductivity. The real-time monitoring signal of the sensor is the change in its resistance value.

[0020] The beneficial effects of this invention are:

[0021] (1) The present invention uses a hydrothermal method to obtain a novel heterojunction composite nanomaterial. The raw materials are readily available and inexpensive, and the preparation process of the heterojunction is simple. It is a two-dimensional semiconductor heterojunction preparation scheme with low equipment investment and simple process flow.

[0022] (2) The composite material of the present invention has In2S3 nanoparticles uniformly distributed on the flower-like SnS2 surface, which has a large surface area-to-volume ratio structure. At the same time, tin dioxide and indium trisulfide form a heterojunction, which can guide electrons to accumulate on the surface material, enhance the gas-sensitive selectivity of the material, and the electron migration between tin dioxide and indium trisulfide helps to promote additional oxygen adsorption on the material surface, thereby improving the gas-sensitive performance at room temperature.

[0023] (3) This invention greatly reduces the temperature required for sensor operation, allowing it to work at room temperature and slowing down material aging and damage caused by working in high-temperature environments. At the same time, the lower operating temperature makes it possible to design and manufacture portable mobile devices. Attached Figure Description

[0024] Figure 1 This is a scanning electron microscope image of the SnS2 / In2S3 nanocomposite material of the present invention.

[0025] Figure 2 This is a comparison chart showing the response of the SnS2 / In2S3 nanocomposite gas sensor of the present invention to several common volatile interfering gases and ammonia.

[0026] Figure 3 The graph shows the response curves of the SnS2 / In2S3 nanocomposite gas-sensitive element under different ammonia concentrations. Detailed Implementation

[0027] The embodiments of the present invention are described in detail below. These embodiments are implemented based on the technical solution of the present invention, and provide detailed implementation methods and specific operation processes. However, the scope of protection of the present invention is not limited to the following embodiments.

[0028] Example 1

[0029] (1) Dissolve 0.54g of tin tetrachloride pentahydrate (SnCl4·5H2O) and 0.49g of thioacetamide (TAA) in 30mL of isopropanol solution and stir for 30 minutes at room temperature until the solution is clear and transparent.

[0030] (2) Add 0.214g of In2O3 nanoparticles to the mixed solution obtained in step (1), wherein the molar ratio of In2O3 and SnCl4·5H2O is 1:2. Stir vigorously until the In2O3 nanoparticles are completely dispersed, and then sonicate for 1h under ultrasonic power of 240W~260W to obtain a uniform suspension.

[0031] (3) The suspension obtained in step (2) was transferred to a hydrothermal reactor lined with polytetrafluoroethylene and subjected to hydrothermal reaction at 180°C for 16 hours. The product after hydrothermal reaction was then separated into solid and liquid by centrifuge. The obtained solid product was washed repeatedly with deionized water and anhydrous ethanol. The obtained solid product was placed in a drying oven and dried at 60°C to obtain tin disulfide and indium trisulfide heterojunction composite nanomaterials.

[0032] (4) Grind the SnS2 / In2S3 nanocomposite material into powder, then disperse the ground SnS2 / In2S3 nanocomposite material powder into deionized water, and sonicate it into a dispersion of 8mg / mL to 10mg / mL. Then take the dispersion and coat it onto the surface of the interdigitated electrode plate, place it in a drying oven at 60°C for 4 to 6 hours, and cool it naturally to room temperature to obtain the SnS2 / In2S3 nanocomposite material gas sensor.

[0033] Example 2

[0034] (1) Dissolve 0.54g of tin tetrachloride pentahydrate (SnCl4·5H2O) and 0.49g of thioacetamide (TAA) in 30mL of isopropanol solution and stir for 30 minutes at room temperature until the solution is clear and transparent.

[0035] (2) Add 0.143g of In2O3 nanoparticles to the mixed solution obtained in step (1), wherein the molar ratio of In2O3 and SnCl4·5H2O is 1:3. Stir vigorously until the In2O3 nanoparticles are completely dispersed, and then sonicate for 1h under ultrasonic power of 240W~260W to obtain a uniform suspension.

[0036] (3) The suspension obtained in step (2) was transferred to a hydrothermal reactor lined with polytetrafluoroethylene and subjected to hydrothermal reaction at 180°C for 16 hours. The product after hydrothermal reaction was then separated into solid and liquid by centrifuge. The obtained solid product was washed repeatedly with deionized water and anhydrous ethanol. The obtained solid product was placed in a drying oven and dried at 60°C to obtain tin disulfide and indium trisulfide heterojunction composite nanomaterials.

[0037] (4) Grind the SnS2 / In2S3 nanocomposite material into powder, then disperse the ground SnS2 / In2S3 nanocomposite material powder into deionized water, and sonicate it into a dispersion of 8mg / mL to 10mg / mL. Then take the dispersion and coat it onto the surface of the interdigitated electrode plate, place it in a drying oven at 60°C for 4 to 6 hours, and cool it naturally to room temperature to obtain the SnS2 / In2S3 nanocomposite material gas sensor.

[0038] Example 3

[0039] (1) Dissolve 0.54g of tin tetrachloride pentahydrate (SnCl4·5H2O) and 0.49g of thioacetamide (TAA) in 30mL of isopropanol solution and stir for 30 minutes at room temperature until the solution is clear and transparent.

[0040] (2) Add 0.107g of In2O3 nanoparticles to the mixed solution obtained in step (1), wherein the molar ratio of In2O3 and SnCl4·5H2O is 1:4. Stir vigorously until the In2O3 nanoparticles are completely dispersed, and then sonicate for 1h under ultrasonic power of 240W~260W to obtain a uniform suspension.

[0041] (3) The suspension obtained in step (2) was transferred to a hydrothermal reactor lined with polytetrafluoroethylene and subjected to hydrothermal reaction at 180°C for 16 hours. The product after hydrothermal reaction was then separated into solid and liquid by centrifuge. The obtained solid product was washed repeatedly with deionized water and anhydrous ethanol. The obtained solid product was placed in a drying oven and dried at 60°C to obtain tin disulfide and indium trisulfide heterojunction composite nanomaterials.

[0042] (4) Grind the SnS2 / In2S3 nanocomposite material into powder, then disperse the ground SnS2 / In2S3 nanocomposite material powder into deionized water, and sonicate it into a dispersion of 8mg / mL to 10mg / mL. Then take the dispersion and coat it onto the surface of the interdigitated electrode plate, place it in a drying oven at 60°C for 4 to 6 hours, and cool it naturally to room temperature to obtain the SnS2 / In2S3 nanocomposite material gas sensor.

Claims

1. An ammonia gas sensor based on SnS2 and In2S3 heterojunction, characterized in that, The ammonia gas sensor mainly consists of a gas-sensitive material and an interdigitated electrode plate. The gas-sensitive material is coated on the surface of the interdigitated electrode plate with a coating thickness of 20μm~80μm. The gas-sensitive material is a heterojunction composite nanomaterial of tin disulfide and indium trisulfide. The heterojunction composite nanomaterial of tin disulfide and indium trisulfide is formed by attaching indium trisulfide to the surface of flower-shaped tin disulfide using a hydrothermal method.

2. The ammonia gas sensor according to claim 1, characterized in that, The interdigitated electrode plate is an alumina substrate with pure gold electrodes on the front side, with 3 to 10 pairs of interdigitated fingers and a thickness of 2 to 5 μm.

3. The ammonia gas sensor according to claim 1 or 2, characterized in that, The ammonia gas sensor operates at room temperature, achieving material integration with silicon-based microelectronics.

4. A fabrication process for an ammonia gas sensor based on SnS2 and In2S3 heterojunctions, characterized in that, Includes the following steps: (1) Dissolve SnCl4·5H2O and thioacetamide in isopropanol in sequence, control the molar ratio of SnCl4·5H2O and thioacetamide to be 1:4~5, and stir vigorously until completely dissolved to obtain a mixed solution; (2) Add In2O3 nanoparticles to the mixed solution obtained in step (1), control the molar ratio of In2O3 and SnCl4·5H2O to 1:2~4, stir vigorously until the In2O3 nanoparticles are completely dispersed, and then perform ultrasonic treatment for 1~2 hours to obtain a uniform suspension. (3) The suspension obtained in step (2) is transferred to a hydrothermal reactor lined with polytetrafluoroethylene. The hydrothermal reaction is carried out at 160~200℃ for 12~24 h. The product after the hydrothermal reaction is then separated into solid and liquid by centrifuge. The obtained solid product is washed repeatedly with deionized water and anhydrous ethanol. The obtained solid product is placed in a drying oven and dried at 60℃ to obtain tin disulfide and indium trisulfide heterojunction composite nanomaterials. (4) Grind the tin disulfide and indium trisulfide heterojunction composite nanomaterials into powder, then disperse the ground tin disulfide and indium trisulfide heterojunction composite nanomaterial powder in deionized water, and sonicate it into a dispersion of 8 mg / mL to 10 mg / mL. Then take the dispersion and coat it onto the surface of the interdigitated electrode plate, place it in a drying oven at 60°C for 4 to 6 hours, and let it cool naturally to room temperature to obtain the SnS2 / In2S3 nanocomposite gas sensor.

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