Heterogeneous metal atom doped Bi2S3 nano material, preparation method thereof, gas sensor and application

Abstract

The invention relates to the technical field of gas sensing, in particular to a heterogeneous metal atom doped Bi2S3 nano material, a preparation method thereof, a gas sensor and application, the preparation method of the heterogeneous metal atom doped Bi2S3 nano material comprises the following steps: mixing bismuth salt, bromine salt, a sulfur source, a surfactant and an organic solvent to obtain a mixture; and mixing the mixture with a salt containing heterogeneous metal atoms, and carrying out a solvothermal reaction to obtain the heterogeneous metal atom doped Bi2S3 nano material. The heterogeneous metal atom doped Bi2S3 nano material is successfully synthesized by using a simple one-step solvothermal method, the morphology of the nano material synthesized by using the method comprises a one-dimensional nano wire, a two-dimensional nano sheet and a three-dimensional nano flower, the morphology has a relatively high specific surface area, full contact between NO2 gas molecules and active sites is increased, charge transfer is accelerated, and the performance of the nano material is improved. Therefore, the sensitivity in the gas sensing process is improved.

Description

Technical Field

[0001] The present invention relates to the field of gas sensing technology, in particular to a heterogeneous metal atom doped Bi 2 S 3 Nanomaterials and their preparation methods, gas sensors and applications. Background Art

[0002] In the past few decades, metal oxides have been used on a large scale as the main resistive gas sensing material. However, due to the wide band gap of metal oxides, they have high operating temperatures (150℃-400℃), high power consumption and safety hazards. In addition, metal oxides have a broad spectrum response to a variety of gases and are easily interfered by non-target atmospheres in complex atmospheres. Compared with metal oxides, metal sulfides have narrow band gaps and high electron mobility, which are conducive to the gas-sensitive response process at low operating temperatures.

[0003] Currently, doping is often used to modify gas-sensitive materials. However, due to the lack of reliable functionalization strategies, the selection of doped metal atoms follows standards, the uniform functionalization method on the metal sulfide-based sensing layer in a highly controlled manner, and the integration of materials in micro or flexible devices after doping have always limited their application in sensing.

[0004] Therefore, the prior art still needs to be improved and developed. Summary of the invention

[0005] In view of the above-mentioned shortcomings of the prior art, the object of the present invention is to provide a heterogeneous metal atom doped Bi 2 S 3 Nanomaterials and their preparation methods, gas sensors and applications are designed to solve the problem of weak interaction between existing gas-sensitive materials and target molecules and low sensitivity.

[0006] The technical solution of the present invention is as follows:

[0007] A heterogeneous metal atom doped Bi 2 S 3 The method for preparing nanomaterials comprises the following steps:

[0008] Mixing a bismuth salt, a bromine salt, a sulfur source, a surfactant and an organic solvent to obtain a mixture;

[0009] The mixture is mixed with a salt containing a heterogeneous metal atom, and after a solvent thermal reaction, a heterogeneous metal atom-doped Bi is obtained. 2 S 3 Nanomaterials.

[0010] The heterogeneous metal atom doped Bi 2 S 3A method for preparing a nanomaterial, wherein the bismuth salt comprises one or more of bismuth nitrate, bismuth chloride, bismuth sulfate, and bismuth acetate; and the sulfur source comprises one or more of sodium sulfide, thiourea, sodium hydrosulfide, and thioacetamide.

[0011] The heterogeneous metal atom doped Bi 2 S 3 A method for preparing a nanomaterial, wherein the heterogeneous metal atoms include one or more of lead, tin, copper, iron, indium, and tungsten.

[0012] The heterogeneous metal atom doped Bi 2 S 3 A method for preparing a nano material, wherein the bromine salt comprises one or more of potassium bromide, sodium bromide, and lithium bromide.

[0013] The heterogeneous metal atom doped Bi 2 S 3 A method for preparing a nanomaterial, wherein the mass ratio of the bismuth salt, the bromide salt, the sulfur source and the salt containing heterogeneous metal atoms is (1-3):(2-5):(0.6-2):(0.05-0.3).

[0014] The heterogeneous metal atom doped Bi 2 S 3 The method for preparing nanomaterials, wherein the temperature of the solvent thermal reaction is 120°C-180°C, and the time of the solvent thermal reaction is 2h-12h.

[0015] A heterogeneous metal atom doped Bi 2 S 3 Nanomaterials, using heterogeneous metal atoms to dope Bi 2 S 3 The nanomaterial is prepared by a method for preparing the nanomaterial.

[0016] The heterogeneous metal atom doped Bi 2 S 3 Nanomaterial, wherein the heterogeneous metal atom is doped with Bi 2 S 3 The morphology of nanomaterials includes one or more of one-dimensional nanowires, two-dimensional nanosheets, and three-dimensional nanoflowers.

[0017] A gas sensor comprises a ceramic sheet printed with interdigital electrodes and a gas sensing sensitive layer arranged on the interdigital electrodes; the gas sensing sensitive layer is formed by doping Bi with the heterogeneous metal atoms. 2 S 3 Made of nanomaterials.

[0018] The invention discloses an application of a gas sensor in a device for detecting nitrogen dioxide.

[0019] Beneficial effect: The present invention provides a heterogeneous metal atom doped Bi 2 S 3 Nanomaterials and their preparation methods, gas sensors and applications, heterogeneous metal atoms doped with Bi 2 S 3 The preparation method of the nanomaterial comprises the steps of: mixing bismuth salt, bromine salt, sulfur source, surfactant and organic solvent to obtain a mixture; mixing the mixture with salt containing heterogeneous metal atoms, and obtaining heterogeneous metal atom-doped Bi after solvent thermal reaction. 2 S 3 Nanomaterials. The present invention successfully synthesized heterogeneous metal atom-doped Bi using a simple one-step solvothermal method. 2 S 3 Nanomaterials, the morphology of the nanomaterials synthesized by this method includes one-dimensional nanowires, two-dimensional nanosheets, and three-dimensional nanoflowers. The morphology has a high specific surface area and increases NO 2 The gas molecules are in full contact with the active sites, and the charge transfer is accelerated, which is beneficial to improve the sensitivity of the gas sensing process. In addition, the heterogeneous metal atom doping introduces additional active sites, which can effectively regulate the band structure and carrier concentration of the material, enhance the interaction between the material and the target gas molecules, and make the heterogeneous metal atom doped Bi 2 S 3 Nanomaterials can react with NO at room temperature 2 It has highly sensitive and rapid specific detection; in addition, the entire preparation process of the nanomaterial is simple, efficient and environmentally friendly, and the obtained nanomaterial can form a stable colloidal solution and integrate with the substrate, laying the foundation for industrial preparation and application of wearable devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The present invention is a heterogeneous metal atom doped Bi 2 S 3 Schematic diagram of the process flow of the nanomaterial preparation method;

[0021] Figure 2 The Pb-Bi prepared in Example 1 2 S 3 Nanowire powder and Bi prepared in Comparative Example 1 2 S 3 XRD patterns of nanomaterials;

[0022] Figure 3 The Pb-Bi prepared in this example 2 S 3 SEM and TEM images of nanowire powder;

[0023] Figure 4Pb-Bi obtained by vacuum filtration 2 S 3 Optical images of flexible films on flexible substrates;

[0024] Figure 5 Gas sensor device for 10ppm NO at room temperature 2 Room temperature sensing performance data graph;

[0025] Figure 6 Selectivity test data of gas sensor devices to interference gases. DETAILED DESCRIPTION

[0026] The present invention provides a heterogeneous metal atom doped Bi 2 S 3 Nanomaterials and preparation methods thereof, gas sensors and applications, in order to make the purpose, technical solutions and effects of the present invention clearer and more specific, the present invention is further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0027] It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as generally understood by those skilled in the art in the art to which the present invention belongs. It should also be understood that terms such as those defined in general dictionaries should be understood to have meanings consistent with the meanings in the context of the prior art, and will not be interpreted with idealized or overly formal meanings unless specifically defined as herein.

[0028] Metal ion doping, as a commonly used modification strategy for gas-sensitive materials, can enhance their gas-sensing properties by creating lattice distortions and defects on the crystal. First, doping ions can change the electronic structure of the matrix material. Second, metal doping introduces additional active sites, which enhance activity and selectivity when interacting with target analytes. Third, the strong metal-sulfur interaction between metal atoms and the matrix helps to improve performance stability and service life.

[0029] Based on this, Figure 1 As shown, the present invention provides a heterogeneous metal atom doped Bi 2 S 3 The method for preparing nanomaterials comprises the following steps:

[0030] Step S10: mixing a bismuth salt, a bromine salt, a sulfur source, a surfactant and an organic solvent to obtain a mixture;

[0031] Step S20: Mixing the mixture with a salt containing heterogeneous metal atoms, and obtaining heterogeneous metal atom-doped Bi after solvent thermal reaction. 2 S3 Nanomaterials.

[0032] In this embodiment, a simple one-step solvothermal method was used to successfully synthesize heterogeneous metal atom-doped Bi 2 S 3 Nanomaterials, the morphology of the nanomaterials synthesized by this method includes one-dimensional nanowires, two-dimensional nanosheets, and three-dimensional nanoflowers. The morphology has a high specific surface area and increases NO 2 The gas molecules are in full contact with the active sites, and the charge transfer is accelerated, which is beneficial to improve the sensitivity of the gas sensing process. In addition, the heterogeneous metal atom doping introduces additional active sites, which can effectively regulate the band structure and carrier concentration of the material, enhance the interaction between the material and the target gas molecules, and make the heterogeneous metal atom doped Bi 2 S 3 Nanomaterials can react with NO at room temperature 2 It has highly sensitive and rapid specific detection; in addition, the entire preparation process of the nanomaterial is simple, efficient and environmentally friendly, and the obtained nanomaterial can form a stable colloidal solution and integrate with the substrate, laying the foundation for industrial preparation and application of wearable devices.

[0033] Specifically, the surface activity and incomplete recovery of traditional metal sulfides at room temperature limit their gas sensitivity, and the large particle size of the matrix material or the unstable ions after doping hinder their process integration on flexible or micro devices. The present invention introduces heterogeneous metal atoms by doping, which can regulate the band structure and carrier concentration of the material. While introducing additional active sites, the strong metal-sulfur interaction between the matrix material and the doped ions improves the stability and service life of the material performance, which is extremely beneficial to the sensing performance at room temperature; the growth of bismuth sulfide nanomaterials is jointly regulated by surfactants and bromide salts, thereby realizing the preparation of nanomaterials and their uniform integration on flexible substrates. In addition, heterogeneous metal atom-doped Bi was prepared using a simple solvothermal method and a chemical reagent regulation strategy. 2 S 3 Nanomaterials, simple methods, low cost; metal doping regulates the energy band and surface structure of materials, improving the room temperature resistance to NO 2 The sensing sensitivity is high and the response recovery is fast. 2 It has broad application prospects in various aspects; at the same time, the material is easily dispersed into a colloidal solution, the device preparation process is simple, and flexible films can be made, which has high commercial application value.

[0034] In some embodiments, the bismuth salt includes but is not limited to one or more of bismuth nitrate, bismuth chloride, bismuth sulfate, and bismuth acetate; the sulfur source includes but is not limited to one or more of sodium sulfide, thiourea, sodium hydrosulfide, and thioacetamide. 2 S 3 Nanomaterials provide Bi and S elements, which can produce high-purity heterogeneous metal atoms doped with Bi. 2 S 3 Nanomaterials, and the above materials are relatively low in price, which is conducive to actual production and promotion.

[0035] In some embodiments, the heterogeneous metal atoms include but are not limited to one or more of lead, tin, copper, iron, indium, and tungsten. By doping bismuth sulfide with the above heterogeneous metal atoms, additional active sites can be introduced, which can effectively regulate the energy band structure and carrier concentration of the material, enhance the interaction between the material and the target gas molecules, and make the M-Bi doped with the heterogeneous metal atoms M 2 S 3 At room temperature, NO 2 It has high sensitivity and fast reaction speed to achieve specific detection.

[0036] In some embodiments, the surfactant includes, but is not limited to, one or more of polyvinyl pyrrolidone, sodium dodecyl sulfate, hexadecyltrimethylammonium bromide, and sodium dodecylbenzene sulfonate.

[0037] In some embodiments, the bromide salt includes, but is not limited to, one or more of potassium bromide, sodium bromide, and lithium bromide.

[0038] Specifically, the growth of bismuth sulfide nanomaterials was regulated by using surfactants and bromide salts, achieving the preparation of nanomaterials and their uniform integration on flexible substrates. By using the combined action of surfactants and bromide salts, heterogeneous metal atoms doped with Bi in the form of one-dimensional nanowires, two-dimensional nanosheets, and three-dimensional nanoflowers can be prepared. 2 S 3 Nanomaterials.

[0039] In some embodiments, the mass ratio of the bismuth salt, the bromide salt, the sulfur source and the salt containing heterogeneous metal atoms is (1-3): (2-5): (0.6-2): (0.05-0.3). Controlling the mass ratio of the bismuth salt, the bromide salt, the sulfur source and the salt containing heterogeneous metal atoms within the above range can improve the purity of the product, and can effectively regulate the energy band structure and carrier concentration of the material, thereby enhancing the interaction between the material and the target gas molecules.

[0040] In some embodiments, the organic solvent includes, but is not limited to, one of formamide, N,N-dimethylformamide, anhydrous ethanol, and N,N-dimethylacetamide solution.

[0041] In some embodiments, the temperature of the solvothermal reaction is 120°C-180°C, and the time of the solvothermal reaction is 2h-12h. The solvothermal reaction is used to dope heterogeneous metal atoms into bismuth sulfide, introducing additional active sites, which can effectively regulate the band structure and carrier concentration of the material and enhance the interaction between the material and the target gas molecules. The temperature and time are used to regulate the heterogeneous metal atoms doped into Bi 2 S 3 The growth of nanomaterials can effectively control the size of nanomaterials; heterogeneous metal atoms doped with Bi prepared at too high a temperature or for too long a time 2 S 3 The nanomaterials are relatively large in size (for example, the nanowires are relatively thick), and too low a temperature and too short a time will result in poor crystallinity of the product. The above-mentioned solvent thermal reaction temperature and time range are suitable for the preparation of heterogeneous metal atom-doped Bi 2 S 3 Balance values ​​for nanomaterials.

[0042] In some embodiments, in step S20, after the solvothermal reaction, centrifugal washing is further included; specifically, the steps include: cooling naturally after the solvothermal reaction, collecting the product by centrifugation, washing with formamide and water respectively, and collecting the product after freeze drying to obtain the heterogeneous metal atom-doped Bi 2 S 3 Nanomaterials.

[0043] In addition, the present invention also provides a heterogeneous metal atom doped Bi 2 S 3 Nanomaterials, using heterogeneous metal atoms to dope Bi 2 S 3 The nanomaterial is prepared by a method for preparing the nanomaterial.

[0044] In this embodiment, the morphology of the nanomaterial synthesized by this method includes one-dimensional nanowires, two-dimensional nanosheets, and three-dimensional nanoflowers. The morphology has a high specific surface area and increases the NO 2 The gas molecules are in full contact with the active sites, and the charge transfer is accelerated, which is beneficial to improve the sensitivity of the gas sensing process. In addition, the heterogeneous metal atom doping introduces additional active sites, which can effectively regulate the band structure and carrier concentration of the material, enhance the interaction between the material and the target gas molecules, and make the heterogeneous metal atom doped Bi 2 S 3 Nanomaterials can react with NO at room temperature 2 It has high sensitivity and rapid specific detection.

[0045] In some embodiments, the heterogeneous metal atom doped Bi 2 S 3 The morphology of nanomaterials includes one or more of one-dimensional nanowires, two-dimensional nanosheets, and three-dimensional nanoflowers. Nanomaterials in the form of one-dimensional nanowires, two-dimensional nanosheets, and three-dimensional nanoflowers have a higher specific surface area and increase the NO 2 The gas molecules are fully contacted with the active sites and the charge transfer is accelerated, which is beneficial to improve the sensitivity of the gas sensing process. 2 S 3 The morphology of the nanomaterial is one-dimensional nanowires.

[0046] In some embodiments, the heterogeneous metal atoms are used to dope Bi 2 S 3 Preparation of nanomaterials by heterogeneous metal atoms doped with Bi 2 S 3 The flexible film specifically comprises the steps of: doping Bi with heterogeneous metal atoms 2 S 3 The nanomaterials are dispersed in water or other solvents to form a uniform dispersion with a concentration range of 2mg / mL-10mg / mL to facilitate uniform film formation over a large area. The solvent is then removed by vacuum filtration or spray coating and the dispersion is applied to the surface of a flexible substrate. By controlling the concentration of the dispersion, the doping of heterogeneous metal atoms with Bi can be controlled. 2 S 3 The thickness of the flexible film is approximately 0.8mm-3mm. The moderate thickness can take into account both gas adsorption and diffusion and make the device flexible.

[0047] In addition, the present invention also provides a gas sensor, comprising a ceramic sheet printed with interdigital electrodes, and a gas sensing sensitive layer arranged on the interdigital electrodes; the gas sensing sensitive layer is formed by doping Bi with the heterogeneous metal atoms. 2 S 3 Made of nanomaterials.

[0048] In some embodiments, the method for preparing the gas sensor comprises the steps of: ultrasonically cleaning a ceramic sheet printed with silver palladium interdigitated electrodes in acetone, water and ethanol for 30 minutes each, and then drying it in an oven for subsequent testing; doping the heterogeneous metal atoms with Bi 2 S 3 The nanomaterial is mixed with water and evenly dispersed by ultrasound; the evenly dispersed solution is dripped on the silver palladium interdigital electrode with a pipette gun, and the gas sensor is obtained after drying. Preferably, the silver palladium interdigital electrode with flexibility is used as the flexible substrate, and its cutting specification is 0.8*1.5cm.

[0049] At the same time, the present invention also provides an application of a gas sensor in a device for detecting nitrogen dioxide.

[0050] In this embodiment, metal doping regulates the energy band and surface structure of the material, thereby improving the NO 2 The sensing sensitivity is high and the response recovery is fast. 2 It has broad application prospects in various aspects; at the same time, the material is easily dispersed into a colloidal solution, the device preparation process is simple, and flexible films can be made, which has high commercial application value.

[0051] The following examples are further given to illustrate the present invention in detail. It should also be understood that the following examples are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above content of the present invention belong to the scope of protection of the present invention.

[0052] Comparative Example 1

[0053] This comparative example synthesizes Bi 2 S 3 Nanomaterials, specifically including the following steps:

[0054] Weigh 2g of bismuth nitrate, 2g of polyvinyl pyrrolidone (PVP), 1g of thiourea, and 3g of potassium bromide into a polytetrafluoroethylene liner, add 30ml of formamide solution to fully dissolve it, and then transfer the reactor to an oven for solvent thermal reaction at 150°C for 8h. Allow it to cool naturally, collect the product by centrifugation, wash it with formamide and water respectively, and collect the product after freeze drying. (Comparative sample)

[0055] Example 1

[0056] In this example, lead-doped Bi 2 S 3 Nanowires, Pb-Bi 2 S 3 Flexible film and gas sensor device, mainly including the following steps:

[0057] 1)Synthesis of Pb-Bi 2 S 3 Nanowires

[0058] Weigh 2g of bismuth nitrate, 2g of polyvinyl pyrrolidone, 1g of thiourea, and 3g of potassium bromide into a polytetrafluoroethylene liner, add 30ml of formamide solution to fully dissolve it, and after the mixture is fully dispersed, weigh 0.2g of lead nitrate and put it into the reactor. Then transfer the reactor to an oven and perform solvent thermal reaction at 150°C for 8h; wait for it to cool naturally, collect the product by centrifugation, wash it with formamide and water respectively, collect the product after freeze drying, and obtain Pb-Bi 2 S3 Nanowire powder.

[0059] The Pb-Bi prepared in this example 2 S 3 Nanowire powder and Bi prepared in Comparative Example 1 2 S 3 The nanomaterials were characterized and their XRD patterns were shown in Figure 2 As shown in the figure, it can be seen that there is no obvious change in the sample spectrum peak before and after, indicating that lead exists in the form of ion doping in Bi 2 S 3 and corresponds to the standard card 17-0320 for bismuth sulfide.

[0060] The Pb-Bi prepared in this example 2 S 3 The nanowire powder was microscopically characterized, and its SEM and TEM images are shown in Figure 3 As shown, Figure 3 (a) and (b) are Pb-Bi 2 S 3 SEM images of (c) and (d) are Pb-Bi 2 S 3 TEM image; it can be seen that Pb-Bi 2 S 3 The nanowires are stacked in an interlaced manner with a diameter of about 8 to 10 nm.

[0061] 2)Synthesis of Pb-Bi 2 S 3 Flexible film

[0062] Weigh a certain amount of Pb-Bi 2 S 3 The nanowire powder is dispersed in water to form a uniform solution with a concentration of 6 mg / mL so that it can form a uniform film over a large area. The solvent is then removed by vacuum filtration and evenly coated on the surface of the flexible substrate. At this time, by controlling the concentration of the dispersion, the thickness of the flexible layer can be about 2 mm.

[0063] Pb-Bi obtained by vacuum filtration 2 S 3 Optical images of flexible films on flexible substrates Figure 4 Shown (including Figure 4 (a)-(c)), it can be seen that the Pb-Bi 2 S 3 The flexible film has high flexibility and can be bent over 180 degrees.

[0064] 3) Preparation of gas sensor devices

[0065] The ceramic sheet printed with silver-palladium interdigital electrodes was ultrasonically cleaned in acetone, water and ethanol for 30 min each, and then dried in an oven at 60 °C for subsequent testing. 2 S 3 The nanowire powder was placed in an aqueous solution and ultrasonically dispersed to a concentration of 6 mg / mL. 40 μL of the dispersed sample was transferred with a pipette and applied to the silver palladium interdigital electrode. After drying, NO 2 The resistance change test under NO atmosphere was carried out. The flexible substrate was cut into 0.8*1.5cm substrates and then subjected to NO 2 Resistance change test under atmosphere.

[0066] At room temperature, the gas sensor device is sensitive to 10ppm NO 2 The room temperature sensing performance data is shown in the figure Figure 5 As shown in the figure, from the response and recovery curves, it can be seen that for 10ppm nitrogen dioxide, the response time is 96s, the recovery time is 272s, and the response value (the ratio of the resistance before and after the response) is 10.

[0067] The selectivity test data of gas sensor devices for interfering gases is shown in the figure below: Figure 6 As shown, it can be seen that the sample Pb-Bi 2 S 3 Comparison of the response values ​​of different gases proves that the material is sensitive to NO 2 specific response.

[0068] In summary, the present invention provides a heterogeneous metal atom doped Bi 2 S 3 Nanomaterials and their preparation methods, gas sensors and applications, heterogeneous metal atoms doped with Bi 2 S 3 The preparation method of the nanomaterial comprises the steps of: mixing bismuth salt, bromine salt, sulfur source, surfactant and organic solvent to obtain a mixture; mixing the mixture with salt containing heterogeneous metal atoms, and obtaining heterogeneous metal atom-doped Bi after solvent thermal reaction. 2 S 3 Nanomaterials. The present invention successfully synthesized heterogeneous metal atom-doped Bi using a simple one-step solvothermal method. 2 S 3 Nanomaterials, the morphology of the nanomaterials synthesized by this method includes one-dimensional nanowires, two-dimensional nanosheets, and three-dimensional nanoflowers. The morphology has a high specific surface area and increases NO 2The gas molecules are in full contact with the active sites, and the charge transfer is accelerated, which is beneficial to improve the sensitivity of the gas sensing process. In addition, the heterogeneous metal atom doping introduces additional active sites, which can effectively regulate the band structure and carrier concentration of the material, enhance the interaction between the material and the target gas molecules, and make the heterogeneous metal atom doped Bi 2 S 3 Nanomaterials can react with NO at room temperature 2 It has highly sensitive and rapid specific detection; in addition, the entire preparation process of the nanomaterial is simple, efficient and environmentally friendly, and the obtained nanomaterial can form a stable colloidal solution and integrate with the substrate, laying the foundation for industrial preparation and application of wearable devices.

[0069] It should be understood that the application of the present invention is not limited to the above examples. For ordinary technicians in this field, improvements or changes can be made based on the above description. All these improvements and changes should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A method for preparing a heterogeneous metal atom-doped Bi2S3 nanomaterial, characterized in that: Includes steps: Mixing a bismuth salt, a bromine salt, a sulfur source, a surfactant and an organic solvent to obtain a mixture; The mixture is mixed with a salt containing heterogeneous metal atoms, and after a solvent thermal reaction, a heterogeneous metal atom-doped Bi2S3 nanomaterial is obtained.

2. The method for preparing heterogeneous metal atom-doped Bi2S3 nanomaterial according to claim 1, characterized in that: The bismuth salt includes one or more of bismuth nitrate, bismuth chloride, bismuth sulfate, and bismuth acetate; the sulfur source includes one or more of sodium sulfide, thiourea, sodium hydrosulfide, and thioacetamide.

3. The method for preparing heterogeneous metal atom-doped Bi2S3 nanomaterial according to claim 1, characterized in that: The heterogeneous metal atoms include one or more of lead, tin, copper, iron, indium, and tungsten.

4. The method for preparing heterogeneous metal atom-doped Bi2S3 nanomaterial according to claim 1, characterized in that: The bromine salt includes one or more of potassium bromide, sodium bromide and lithium bromide.

5. The method for preparing heterogeneous metal atom-doped Bi2S3 nanomaterial according to claim 1, characterized in that: The mass ratio of the bismuth salt, the bromide salt, the sulfur source and the salt containing heterogeneous metal atoms is (1-3):(2-5):(0.6-2):(0.05-0.3).

6. The method for preparing heterogeneous metal atom-doped Bi2S3 nanomaterial according to claim 1, characterized in that: The temperature of the solvent thermal reaction is 120° C.-180° C., and the time of the solvent thermal reaction is 2 h-12 h.

7. A heterogeneous metal atom doped Bi2S3 nanomaterial, characterized in that: The material is prepared by the method for preparing heterogeneous metal atom-doped Bi2S3 nanomaterials as described in any one of claims 1 to 6.

8. The heterogeneous metal atom-doped Bi2S3 nanomaterial according to claim 7, characterized in that: The morphology of the heterogeneous metal atom-doped Bi2S3 nanomaterial includes one or more of one-dimensional nanowires, two-dimensional nanosheets, and three-dimensional nanoflowers.

9. A gas sensor, characterized in that: It comprises a ceramic sheet printed with interdigital electrodes, and a gas sensing sensitive layer arranged on the interdigital electrodes; the gas sensing sensitive layer is made of the heterogeneous metal atom-doped Bi2S3 nanomaterial as described in any one of claims 7-8.

10. Use of the gas sensor according to claim 9 in a device for detecting nitrogen dioxide.

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