Photoelectric Gas Sensor Based on Ordered Array of Molybdenum Disulfide Microspheres, Preparation Method Thereof, and Application Thereof

Abstract

The present invention relates to the technical field of gas product analysis and detection, and specifically relates to a photoelectric gas sensor based on an ordered array structure of MoS2 microspheres, a preparation method thereof, and an application thereof. The photoelectric gas sensor includes a chamber, in which a substrate, a MoS2 microsphere array sensing layer, and an electrode are arranged from bottom to top. A metal wire is connected to the electrode. The preparation method includes: constructing a microsphere array structure on the surface of the substrate; synthesizing the MoS2 microsphere array sensing layer; and preparing a photoelectric gas sensor based on the MoS2 microsphere array sensing layer. The present invention constructs a three-dimensional structure from two-dimensional materials, increasing the surface area and active sites, making its sensitivity and lowest detection limit superior to those of a planar structure. The photoelectric gas sensor provided by the present invention has the advantages of simple operation, easy portability, high sensitivity, and being able to work under room temperature conditions, etc.

Description

Technical Field

[0001] The present invention relates to the technical field of gas product analysis and detection, and particularly relates to a photoelectric gas sensor based on an ordered array structure of MoS2 microspheres, a preparation method thereof, and an application thereof. Background Art

[0002] Triethylamine is a non-toxic, flammable, explosive, and volatile organic compound, which is commonly used in the production of pharmaceuticals and pesticides, and is also often produced by various spoiled fish and shrimp products. The gas and liquid of triethylamine have a strong irritating effect on the human skin and mucous membranes. Inhaling its vapor can cause disorders in the functions of the respiratory organs, blood circulation system, central nervous system, liver, and other mucous membrane tissues, seriously threatening people's physical and mental health. The American Conference of Governmental Industrial Hygienists (ACGIH) has proposed a threshold limit of 1 ppm. Therefore, rapid and accurate detection of triethylamine gas is of great significance for human physical and mental health, industrial production, and quality monitoring of seafood products.

[0003] So far, the materials for detecting triethylamine gas are mostly metal oxide semiconductors. Such gas sensors often require a relatively high working temperature, resulting in high energy consumption problems. At the same time, there are also safety hazards under high-temperature conditions.

[0004] In recent years, the rapid development of two-dimensional semiconductor materials has brought new detection methods for high-performance room-temperature gas sensors. Among them, two-dimensional gas sensors for detecting toxic and harmful gases such as NO2 and NO have been successfully developed. They utilize the physical adsorption on the surface of two-dimensional semiconductors to regulate the electrical properties of semiconductors, and obtain the detection of gas molecules through electrical signal measurement. However, the research on two-dimensional gas sensors for triethylamine is relatively less. Moreover, the gas sensors based on two-dimensional materials reported currently usually use horizontal thin film materials as the sensitive layer. Since there are no dangling bonds on the surface of the sensitive layer, and most dangling bonds are located at the edges of two-dimensional materials, the main force between the gas and the material is the relatively weak van der Waals force. Therefore, the gas response intensity and sensitivity are relatively low, the detection limit is relatively high, and the recovery characteristics are poor. Summary of the Invention

[0005] Aiming at the above-mentioned defects existing in the prior art, the present invention proposes a photoelectric gas sensor with an ordered array of molybdenum disulfide microspheres, a preparation method thereof, and an application thereof. By constructing a three-dimensional structure, the active sites are increased, and at the same time, the electrical properties of the material are improved by means of the surface scattering effect of light, thereby enhancing the gas detection ability, device stability, and recovery performance of the gas sensor.

[0006] The present invention is implemented by adopting the following technical solutions:

[0007] A preparation method of a photoelectric gas sensor with an ordered array of MoS2 microspheres, including a chamber, in which a substrate, a MoS2 microsphere array sensing layer, and an electrode are arranged from bottom to top, and a metal wire is connected to the electrode.

[0008] The preparation method of the photoelectric gas sensor with an ordered array of MoS2 microspheres includes the following steps:

[0009] S20, Construction of the microsphere array structure on the substrate surface: Regularly arrange the synthesized SiO2 microspheres on the substrate surface to form a SiO2 microsphere template;

[0010] S30, Synthesis of the MoS2 microsphere array sensing layer: Adopt chemical vapor deposition to form a continuous MoS2 thin film layer on the surface of the SiO2 microspheres and the substrate surface, and adopt thermal evaporation to form a MoS2 microsphere array sensing layer on the surface of the MoS2 thin film;

[0011] S40, Preparation of the photoelectric gas sensor based on the MoS2 microsphere array sensing layer: After evaporating the source electrode and the drain electrode on the upper surface of the MoS2 microsphere array sensing layer, place it in the chamber, and connect the source electrode and the drain electrode to metal wires respectively.

[0012] The MoS2 microsphere array sensing layer is a three-dimensional MoS2 sensing layer material jointly composed of a bottom MoS2 thin film layer and a spherical MoS2 layer attached to the surface of the SiO2 microspheres on the MoS2 thin film layer.

[0013] Preferably, the specific operation steps of S20 are as follows:

[0014] S201, Prepare a mixed solution with a volume ratio of anhydrous ethanol to deionized water of (0.9~1.1):1, disperse the synthesized SiO2 microsphere powder into this solution, and make its mass percentage concentration 2-5 wt%;

[0015] S202, Immerse the substrate into the solution formed in S201, slowly pull it out, and form one or more layers of uniformly arranged SiO2 microspheres on its surface by means of surface tension.

[0016] Preferably, the specific operation steps of S30 are as follows:

[0017] S301, Put the MoO3 powder into the reactor, invert the synthesized SiO2 microsphere template on the reactor, and place it in the high-temperature zone of the tube furnace;

[0018] S302, Put the sulfur powder into another reactor and place it at the edge of the tube furnace near the low-temperature zone, and push the reactor containing sulfur powder to the low-temperature zone when the temperature rise ends and the reaction starts;

[0019] S303. Introduce high-purity argon into the tubular furnace at a rate of 15 sccm in volume flow rate, and slowly raise the temperatures of the high-temperature zone and the low-temperature zone to 670 - 690 °C and 250 - 300 °C respectively, and hold for reaction for 20 - 60 min;

[0020] S304. After the reaction in step S303 is completed, let the tubular furnace cool naturally to room temperature to prepare the MoS2 microsphere array sensing layer.

[0021] Preferably, in step S302, the reactor filled with sulfur powder is first placed at the edge of the tubular furnace near the low-temperature zone, and then pushed to the low-temperature zone when the temperature rise ends and the reaction starts.

[0022] Preferably, both the drain electrode and the source electrode are Au electrodes, and the metal wire is an Au wire.

[0023] Preferably, the substrate is one or more of SiO2 / Si substrate, sapphire substrate or mica substrate.

[0024] Preferably, a light source is further provided above the chamber, and preferably an ultraviolet light source.

[0025] Preferably, step S10 includes: Pour ammonia water, anhydrous ethanol and deionized water with a volume fraction / volume ratio of 27:51:75 into beaker A, pour tetraethyl orthosilicate and anhydrous ethanol with a volume fraction / volume ratio of 15:135 into beaker B, shake the solutions in beaker A and beaker B to make a preliminary mixture, then pour the solution in beaker B into beaker A, stir the obtained solution with a magnetic stirrer for 3.5 - 4.5 hours to obtain a uniformly mixed solution; then centrifuge the stirred solution to obtain white solid powder, and wash it 3 - 5 times with deionized water; finally, put the powder into the refrigerator for freezing, and perform freeze-drying for 10 - 16 hours after freezing to obtain the product SiO2 microspheres.

[0026] An optoelectronic gas sensor with an ordered array of MoS2 microspheres is prepared by the above method.

[0027] Preferably, the optoelectronic gas sensor with an ordered array of MoS2 microspheres includes: a substrate at the bottom, a MoS2 microsphere array sensing layer provided above the substrate, electrodes provided on the surface of the MoS2 microsphere array sensing layer and respectively connected with metal wires and a power supply.

[0028] An application of the above optoelectronic gas sensor with an ordered array of MoS2 microspheres in gas product analysis.

[0029] An application of the above optoelectronic gas sensor with an ordered array of MoS2 microspheres in triethylamine gas detection.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1. The three-dimensional structure formed by the two-dimensional materials in the present invention increases the surface area and active sites, making its sensitivity and lowest detection limit superior to those of the planar structure;

[0032] 2. The present invention utilizes the scattering effect of light on the surface of the spherical structure to further improve the electrical properties of the device, thereby affecting its sensitivity and lowest detection limit;

[0033] 3. The detection limit of the present invention under ultraviolet light irradiation is significantly reduced, and the lowest detection limit is 85 ppb;

[0034] 4. The present invention can effectively detect triethylamine at room temperature;

[0035] 5. The preparation method provided by the present invention obtains the three-dimensional structure MoS2 thin film sensing layer material through chemical vapor deposition and treatment of the growth template, increasing the specific surface area and active sites, providing a new idea for improving the performance of gas sensors;

[0036] 6. The optoelectronic gas sensor provided by the present invention has the advantages of simple operation, easy to carry, high sensitivity, and can work at room temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 is a schematic structural diagram of the present invention;

[0038] Figure 2 is a schematic diagram of the preparation of the MoS2 microsphere array sensing layer of the present invention by chemical vapor deposition method;

[0039] Figure 3 (a) is a scanning electron microscope image of the SiO2 microsphere array of Example 1; Figure 3 (b) is a scanning electron microscope image of the microsphere array after growing the MoS2 layer on the substrate and the surface of the SiO2 microsphere array of Example 1 of the present invention;

[0040] Figure 4 is a scanning electron microscope image after the reaction in step S20 in Comparative Example 1;

[0041] Figure 5 is a scanning electron microscope image after the reaction in step S20 in Comparative Example 2;

[0042] Figure 6 are the gas sensing test results of the optoelectronic gas sensors of Comparative Example 1 and Comparative Example 2, where (a) is the result of Comparative Example 1 and (b) is the result of Comparative Example 2;

[0043] Figure 7 are the results of the dynamic response curves of Examples 1 to 3;

[0044] Figure 8 It is the dynamic response curve of the optoelectronic gas sensor of Example 1 to triethylamine gas at different concentrations, where (a) is under dark conditions and (b) is under ultraviolet light irradiation conditions;

[0045] Figure 9 It is the dynamic response curve of the gas sensor of Comparative Example 3 to triethylamine gas at different concentrations, where (a) is under dark conditions and (b) is under ultraviolet light irradiation conditions;

[0046] Figure 10 It is the comparison of the response and recovery times of the optoelectronic gas sensor of Example 1 under dark conditions and ultraviolet light irradiation conditions;

[0047] Figure 11 It is the comparison of the response and recovery times of the optoelectronic gas sensor of Comparative Example 3 under dark conditions and ultraviolet light irradiation conditions;

[0048] Figure 12 It is the Raman spectrum of the ordered structure array film of the MoS2 layer of Example 1;

[0049] Figure 13 It is the selectivity test result of the optoelectronic gas sensor with the ordered array of MoS2 microspheres of Example 1;

[0050] Figure 14 It is the theoretical fitting curve of the response intensity and the test concentration of Example 1;

[0051] Figure 15 It is a schematic diagram of the special structure mechanism of the optoelectronic gas sensor with the ordered array of MoS2 microspheres of the present invention. Detailed implementation mode

[0052] In order to make the purpose and technical solution of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings.

[0053] The optoelectronic gas sensor with the ordered array of MoS2 microspheres described in the present invention can be widely used in the analysis of gas products, especially in the detection of triethylamine gas. Specifically:

[0054] Example 1:

[0055] As Figures 1 - 2 shown, an optoelectronic gas sensor with an ordered array of MoS2 microspheres described in the present invention includes a chamber, in which a substrate, a sensing layer of an ordered array of MoS2 microspheres, and an electrode are arranged from bottom to top, and a metal wire is connected to the electrode. Its preparation method includes the following steps:

[0056] S00, clean the substrate;

[0057] S10, Synthesis of SiO2 microspheres: Take 27 mL of ammonia water, 51 mL of absolute ethanol, and 75 mL of deionized water and pour them into beaker A. Take 15 mL of tetraethyl orthosilicate and 135 mL of absolute ethanol and pour them into beaker B. Shake the solutions in beakers A and B to mix them preliminarily, and then pour the solution in beaker B into beaker A. Stir the obtained solution with a magnetic stirrer for 4 hours to obtain a uniformly mixed solution; then centrifuge the stirred solution to obtain a white solid powder, and wash it with deionized water 3 to 5 times to remove impurities; finally, put the powder into the refrigerator for freezing, and perform freeze-drying for about 12 hours after freezing to remove excess water, obtaining SiO2 microsphere products with an average diameter of 300 nm.

[0058] S20, Construction of the microsphere array structure on the substrate surface: Arrange the synthesized SiO2 microspheres regularly on the substrate surface to form a SiO2 microsphere template. The specific operation is as follows: Prepare a mixed solution with a volume ratio of absolute ethanol to deionized water of 1:1, disperse the synthesized SiO2 microsphere powder into this solution so that its mass percentage concentration is 3 wt%; immerse the substrate into the solution formed above and slowly take it out, and with the help of surface tension, form one or more layers of SiO2 microspheres on its surface. The structure is shown in Figure 3 (a), and it can be seen from the scanning electron microscope image that the SiO2 microspheres are arranged uniformly.

[0059] S30, Synthesis of the MoS2 microsphere array sensing layer: Adopt chemical vapor deposition to form a continuous MoS2 thin film layer on the surface of SiO2 microspheres and the substrate surface, and adopt thermal evaporation to form a MoS2 microsphere array sensing layer on the surface of the MoS2 thin film; the specific operation is as follows: Weigh 0.05 g of MoO3 powder and put it into a porcelain boat. Invert the prepared SiO2 microsphere template on the porcelain boat so that its surface faces the reaction source, and place it in the high-temperature zone of the tube furnace; weigh another 0.1 g of sublimed sulfur and put it into another porcelain boat and place it on the edge of the tube furnace near the low-temperature zone, and push it to the low-temperature zone when the reaction starts after the temperature rise ends; during this reaction process, quickly push the low-temperature desulfurized powder, which is beneficial to the rapid progress of the chemical reaction and can ensure accurate timing of the reaction time; introduce high-purity argon into the tube furnace at a rate of 15 sccm (volume flow rate) as a protective gas, slowly raise the temperatures of the high-temperature zone and the low-temperature zone to 680 °C and 250 °C respectively, and keep the temperature for 30 min; after the reaction, let the tube furnace cool naturally to room temperature. In this way, an ordered structure array sensing layer of MoS2 microspheres with a MoS2 thin film and spherical MoS2 films formed on the surface is obtained, that is, the MoS2 microsphere array sensing layer. The MoS2 microsphere array sensing layer is a three-dimensional MoS2 sensing layer material jointly composed of the bottom MoS2 thin film layer and the spherical MoS2 layer attached to the surface of SiO2 microspheres on the MoS2 thin film layer. The structure after growth is shown inFigure 3 (b).

[0060] S40. Preparation of an optoelectronic gas sensor based on a MoS2 microsphere array sensing layer: After evaporating the source electrode and the drain electrode on the upper surface of the MoS2 microsphere array sensing layer, place it in a chamber. The source electrode and the drain electrode are respectively connected to metal wires. In this embodiment, both the source electrode and the drain electrode are made of Au electrodes, and the metal wires are made of Au wires.

[0061] Example 2:

[0062] An optoelectronic gas sensor with an ordered array of MoS2 microspheres according to the present invention includes a chamber as described in Example 1. A substrate, a MoS2 microsphere array sensing layer, and an electrode are arranged in the chamber from bottom to top. Metal wires are connected to the electrode. The preparation steps are the same as those in Example 1, except that the conditions used in the following preparation steps are different:

[0063] In the synthesis of SiO2 microspheres in S10: Pour 13.5 mL of ammonia water, 25.5 mL of absolute ethanol, and 37.5 mL of deionized water into beaker A. Pour 7.5 mL of tetraethyl orthosilicate and 67.5 mL of absolute ethanol into beaker B. Shake the solutions in beaker A and beaker B to make a preliminary mixture, and then pour the solution in beaker B into beaker A. Stir the obtained solution with a magnetic stirrer for 3.5 hours to obtain a uniformly mixed solution. Then centrifuge the stirred solution to obtain a white solid powder, and wash it with deionized water 3 to 5 times to remove impurities. Finally, put the powder into the refrigerator for freezing, and perform freeze-drying for about 10 hours after freezing to remove excess water to obtain the SiO2 microsphere product.

[0064] In the construction of the microsphere array structure on the substrate surface in S20: Arrange the synthesized SiO2 microspheres regularly on the substrate surface to form a SiO2 microsphere template. The specific operation is as follows: Prepare a mixed solution with a volume ratio of absolute ethanol to deionized water of 0.9:1, disperse the synthesized SiO2 microsphere powder into this solution so that its mass percentage concentration is 2 wt%. Immerse the substrate in the above-formed solution and slowly take it out. With the action of surface tension, form one or more layers of uniformly arranged SiO2 microspheres on its surface.

[0065] S30, Synthesis of the MoS2 microsphere array sensing layer: By means of chemical vapor deposition, a continuous MoS2 thin film layer is formed on the surface of SiO2 microspheres and the substrate surface. By using the method of thermal evaporation, a MoS2 microsphere array sensing layer is formed on the surface of the MoS2 thin film. The specific operation is as follows: Weigh 0.05 g of MoO3 powder and put it into a porcelain boat. Invert the prepared SiO2 microsphere template on the porcelain boat so that its surface faces the reaction source, and place it in the high-temperature zone of the tube furnace. Weigh another 0.1 g of sublimed sulfur and put it into another porcelain boat and place it at the edge of the tube furnace near the low-temperature zone, and then push it to the low-temperature zone when the reaction starts after the temperature rise ends. Pass high-purity argon into the tube furnace at a rate of 15 sccm (volume flow rate) as the protective gas. Slowly raise the temperatures of the high-temperature zone and the low-temperature zone to 670 °C and 270 °C respectively, and keep the temperature for 20 min. After the reaction, let the tube furnace cool naturally to room temperature to obtain the MoS2 microsphere array sensing layer.

[0066] Example 3:

[0067] The optoelectronic gas sensor with an ordered array of MoS2 microspheres according to the present invention includes a chamber. Inside the chamber, a substrate, a MoS2 microsphere array sensing layer, and an electrode are arranged from bottom to top. A metal wire is connected to the electrode. The preparation steps are the same as those in Example 1, except that the conditions used in the following preparation steps are different:

[0068] In S10, in the synthesis of SiO2 microspheres: Pour 27 mL of ammonia water, 51 mL of absolute ethanol, and 75 mL of deionized water into beaker A. Pour 15 mL of tetraethyl orthosilicate and 135 mL of absolute ethanol into beaker B. Shake the solutions in beaker A and beaker B to make a preliminary mixture, and then pour the solution in beaker B into beaker A. Stir the obtained solution with a magnetic stirrer for about 4.5 hours to obtain a uniformly mixed solution. Then centrifuge the stirred solution to obtain a white solid powder, and wash it with deionized water 3 to 5 times to remove impurities. Finally, put the powder into the refrigerator for freezing, and perform freeze-drying for about 16 hours after freezing to remove the excess water to obtain the SiO2 microsphere product.

[0069] In S20, in the construction of the microsphere array structure on the substrate surface: Arrange the synthesized SiO2 microspheres regularly on the substrate surface to form a SiO2 microsphere template. The specific operation is as follows: Prepare a mixed solution with a volume ratio of absolute ethanol to deionized water of 1.1:1. Disperse the synthesized SiO2 microsphere powder into this solution so that its mass percentage concentration is 5 wt%. Immerse the substrate into the above-formed solution and slowly take it out. With the help of the surface tension, form one or more layers of uniformly arranged SiO2 microspheres on its surface.

[0070] In S30, during the synthesis of the MoS₂ microsphere array sensing layer: By chemical vapor deposition, a continuous MoS₂ thin film layer is formed on the surface of SiO₂ microspheres and the substrate surface. By thermal evaporation, a MoS₂ microsphere array sensing layer is formed on the surface of the MoS₂ thin film. The specific operation is as follows: Weigh 0.05 g of MoO₃ powder and put it into a porcelain boat. Invert the prepared SiO₂ microsphere template on the porcelain boat so that its surface faces the reaction source, and place it in the high-temperature zone of the tubular furnace. Weigh another 0.1 g of sublimed sulfur powder and put it into another porcelain boat and place it on the edge of the tubular furnace near the low-temperature zone, and then push it to the low-temperature zone when the reaction starts after the temperature rise ends. Pass high-purity argon into the tubular furnace at a rate of 15 sccm (volume flow rate) as a protective gas. Slowly raise the temperatures of the high-temperature zone and the low-temperature zone to 690 °C and 300 °C respectively, and keep them at this temperature for 60 minutes. After the reaction, let the tubular furnace cool naturally to room temperature to obtain the MoS₂ microsphere array sensing layer.

[0071] Comparative Example 1:

[0072] The optoelectronic gas sensor with an ordered array of MoS₂ microspheres according to the present invention includes a chamber as described in Example 1. Inside the chamber, a substrate, a MoS₂ microsphere array sensing layer, and an electrode are arranged from bottom to top. A metal wire is connected to the electrode. Its preparation steps are the same as those in Example 1, except that the conditions used in the following preparation steps are different:

[0073] In S20, during the construction of the microsphere array structure on the substrate surface: Arrange the synthesized SiO₂ microspheres regularly on the substrate surface to form a SiO₂ microsphere template. The specific operation is as follows: Prepare a mixed solution with a volume ratio of absolute ethanol to deionized water of 2:1, disperse the synthesized SiO₂ microsphere powder into this solution so that its mass percentage concentration is 1 wt%. Immerse the substrate into the above-formed solution and slowly take it out. With the action of surface tension, SiO₂ microspheres are formed on its surface. The structure can be seen from Figure 4 , and it can be seen from the scanning electron microscope image that the SiO₂ microspheres are arranged loosely.

[0074] Comparative Example 2:

[0075] The optoelectronic gas sensor with an ordered array of MoS₂ microspheres according to the present invention includes a chamber as described in Example 1. Inside the chamber, a substrate, a MoS₂ microsphere array sensing layer, and an electrode are arranged from bottom to top. A metal wire is connected to the electrode. Its preparation steps are the same as those in Example 1, except that the conditions used in the following preparation steps are different:

[0076] S20, Construction of the microsphere array structure on the substrate surface: Arrange the synthesized SiO2 microspheres regularly on the substrate surface to form a SiO2 microsphere template. The specific operation is as follows: Prepare a mixed solution with a volume ratio of anhydrous ethanol to deionized water of 1:2, disperse the synthesized SiO2 microsphere powder into this solution to make its mass percentage concentration 10 wt%; Immerse the substrate into the solution formed above and slowly take it out. With the help of surface tension, SiO2 microspheres are formed on its surface. Its structure is as Figure 5 shown, and the SiO2 microspheres are randomly and densely packed.

[0077] Comparative Example 3:

[0078] An optoelectronic gas sensor with an ordered array of MoS2 microspheres according to the present invention includes a chamber as described in Example 1. A substrate, a MoS2 sensing layer, and an electrode are arranged in the chamber from bottom to top. A metal wire is connected to the electrode. The preparation steps are as follows:

[0079] S00, Clean the SiO2 substrate;

[0080] S30, Synthesis of the MoS2 microsphere array sensing layer: By chemical vapor deposition, directly form a continuous MoS2 thin film layer on the surface of the SiO2 substrate. By thermal evaporation, prepare an electrode layer on the surface of the MoS2 thin film. The specific operation is as follows: Weigh 0.05 g of MoO3 powder and put it into a porcelain boat. Invert the SiO2 substrate on the porcelain boat so that its surface faces the reaction source, and place it in the high-temperature zone of the tube furnace; Weigh another 0.1 g of sublimed sulfur and put it into another porcelain boat and place it at the edge of the tube furnace near the low-temperature zone, and push it to the low-temperature zone when the reaction starts after the temperature rise ends; Pass high-purity argon into the tube furnace at a rate of 15 sccm (volume flow rate) as a protective gas, slowly raise the temperatures of the high-temperature zone and the low-temperature zone to 680 °C and 250 °C respectively, and keep the temperature for 30 min; After the reaction, let the tube furnace cool naturally to room temperature. In this way, a MoS2 thin film sensing layer is obtained. The MoS2 thin film sensing layer is made by the preparation steps of S40 in Example 1 to make an optoelectronic gas sensor with a structure similar to that of Example 1.

[0081] The dynamic response curves of the optoelectronic gas sensors prepared in the above Examples 1 to 3 and Comparative Examples 1 to 2 to triethylamine were respectively measured under ultraviolet light conditions. The specific detection method is as follows:

[0082] In a closed cavity with a fixed volume, the wires led out from the device electrodes are respectively connected to a test power supply system (Keithley 2400). The test system applies a voltage between the two wires. By injecting different amounts of test gas into the test cavity, a test atmosphere with a certain concentration gradient is obtained. Under a certain gas injection time, the test cavity is exposed to the atmospheric environment and waits for the device to recover until the test baseline returns to the initial state. Then, the next concentration test is carried out, and the change of current with concentration during the whole test process is continuously recorded, and the dynamic response curve of the device can be obtained.

[0083] As Figure 6 shown by the gas-sensing test results of Comparative Example 1 and Comparative Example 2, under ultraviolet light conditions, the test atmospheres with concentration gradients of 5 ppm, 10 ppm, 20 ppm, 50 ppm, 100 ppm, and 200 ppm, and the gas injection time is 200 s. The currents of the gas sensor devices prepared in Comparative Example 1 and Comparative Example 2 are 0, it is difficult to achieve electrical conduction, and the dynamic response curve cannot be obtained; as Figure 7 shown, Examples 1 to 3 can all achieve electrical conduction, produce an effective response to the gas test, and obtain the corresponding dynamic response curve.

[0084] The dynamic response curves of the optoelectronic gas sensors prepared in Example 1 and Comparative Example 3 above to triethylamine under dark conditions and ultraviolet light conditions are as follows. Under dark conditions, the test atmospheres with concentration gradients of 50 ppm, 100 ppm, 200 ppm, 500 ppm, and 1000 ppm, and under ultraviolet light conditions, the test atmospheres with concentration gradients of 5 ppm, 10 ppm, 20 ppm, 50 ppm, 100 ppm, and 200 ppm, and the gas injection time is 200 s. As Figure 8 shown by the results, when ultraviolet light irradiation is increased, the lowest detection concentration of the device is reduced to 5 ppm. At the same time, in the environment of triethylamine gas with the same concentration, ultraviolet light can significantly increase the response value of the gas sensor, proving that the gas sensor of Example 1 has a good optoelectronic effect, and under light conditions, the response intensity is greatly improved. And as Figure 9 (b) shown, Comparative Example 3 is a gas sensor formed by using the traditional MoS2 thin film preparation method. Its lowest detection concentration under ultraviolet light irradiation is 10 ppm, which is significantly higher than the lowest detection concentration of Example 1. And by comparing Figure 8 and Figure 9 the ordinate response intensity values, it can be seen that Example 1 has a significantly higher response intensity whether under dark conditions or ultraviolet light conditions, and has better detection sensitivity to triethylamine gas.

[0085] As Figure 10As shown in the figure, the response and recovery speeds of the gas sensor in an environment of triethylamine with a concentration of 200 ppm were compared under the conditions of no light and increased ultraviolet light in Example 1. The injection gas holding time was 200 s, and the recovery time was the time to return to the initial position of the device. It was observed that the response time was 135 s and the recovery time was 20 s under the condition of no light; the response time was 100 s and the recovery time was 17 s under the condition of ultraviolet light, and both the response time and the recovery time were improved to a certain extent. And as Figure 11 shown, in Comparative Example 3, the response time and recovery time under the condition of no light were 152 s and 485 s respectively; the response and recovery times under the condition of ultraviolet light were 134 s and 315 s respectively, and the performance was significantly lower than that of the optoelectronic gas sensor with an ordered array of MoS2 microspheres prepared in this Example 1.

[0086] Further analysis was carried out on the performance of the optoelectronic gas sensor prepared in Example 1:

[0087] As Figure 12 shown, after the growth of the MoS2 microsphere array sensing layer synthesized in step S30 of the above Example 1 was completed, Raman spectroscopy characterization was carried out on its surface, and Raman peaks at 382 cm -1 and 404 cm -1 indicated that a MoS2 thin film was grown on its surface.

[0088] As Figure 13 shown, the optoelectronic gas sensor with an ordered array of MoS2 microspheres prepared in the above Example 1 was used for the detection of various toxic and harmful gases. The results showed that it had obvious selectivity for triethylamine and the highest response degree.

[0089] As Figure 14 shown, through the theoretical fitting of the response intensity and test concentration of the experimental data in Example 1, by obtaining the slope and standard deviation of the linear fitting, through the formula: lowest detection limit = 3 * standard deviation / slope, the lowest detection limit of the above device could reach 85 ppb, and the detection limit was low.

[0090] The present invention has greatly improved in terms of detection sensitivity and recovery speed, etc., and shows excellent properties in comprehensive performance, especially the performance is significantly improved under light conditions. The reason lies in the special structural mechanism, specifically as Figure 15As shown, first, the spherical structure of the present invention provides a larger specific surface area, facilitating the provision of more active sites for gas adsorption. Secondly, when light irradiates the surface of the closely packed spherical array structure MoS2 layer, multiple reflections and scattering occur, which can promote the conversion of light, increase the photocurrent, enhance the photoelectric effect of the device, and increase the current density during the device transmission process, making it more sensitive to the change in carrier concentration caused by the toxic gas triethylamine and improving the sensitivity. Finally, during desorption, ultraviolet light can provide higher energy, making the gas desorption process relatively easy, which is also an important factor for the improvement of the recovery speed of the optoelectronic gas sensor of the present invention.

[0091] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "vertical", "upper", "lower", "horizontal", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0092] In the description of the present invention, it should also be noted that unless otherwise clearly specified and limited, the terms "set", "installed", "connected", "connected", "communicated" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0093] The above is only the preferred embodiment of the present invention and is not intended to limit the present invention. Any equivalent modifications, equivalent substitutions, and improvements made within the spirit and principle of the present invention shall be included within the scope of the patent of the present invention.

Claims

1. A preparation method of a photoelectric gas sensor with an ordered array of molybdenum disulfide microspheres, characterized in that, It includes a chamber, in which a substrate, a MoS2 microsphere array sensing layer, and an electrode are arranged from bottom to top. A metal wire is connected to the electrode. Its preparation method includes the following steps: S10, Synthesis of SiO2 microspheres: Using ammonia water, absolute ethanol, tetraethyl orthosilicate, and deionized water as raw materials, SiO2 microspheres are synthesized by the sol-gel method. The specific operation steps are as follows: Pour ammonia water, absolute ethanol, and deionized water with a volume ratio of 27:51:75 into beaker A, and pour tetraethyl orthosilicate and absolute ethanol with a volume ratio of 15:135 into beaker B. Shake the solutions in beaker A and beaker B to make a preliminary mixture, then pour the solution in beaker B into beaker A. Stir the obtained solution with a magnetic stirrer for 3.5 - 4.5 hours to obtain a uniformly mixed solution; then centrifuge the stirred solution to obtain a white solid powder, and wash it with deionized water 3 - 5 times; finally, put the powder into the refrigerator for freezing, and perform freeze-drying for 10 - 16 hours after freezing to obtain the product SiO2 microspheres; S20, Construction of the microsphere array structure on the substrate surface: Arrange the synthesized SiO2 microspheres regularly on the substrate surface to form a SiO2 microsphere template. The specific operation steps are as follows: S201, Prepare a mixed solution with a volume ratio of (0.9 - 1.1):1 of absolute ethanol and deionized water, disperse the synthesized SiO2 microsphere powder into this solution to make its mass percentage concentration 2 - 5wt%; S202, Immerse the substrate into the solution formed in S201 and slowly take it out, and a layer or multiple layers of uniformly arranged SiO2 microspheres are formed on its surface by the action of surface tension; S30, Synthesis of the MoS2 microsphere array sensing layer: By chemical vapor deposition, a MoS2 microsphere array sensing layer is formed on the surface of the SiO2 microspheres and the substrate surface; S40, Preparation of the optoelectronic gas sensor based on the MoS2 microsphere array sensing layer: After evaporating the source electrode and the drain electrode on the upper surface of the MoS2 microsphere array sensing layer, put it into the chamber, and the source electrode and the drain electrode are respectively connected with metal wires.

2. The preparation method of the photoelectric gas sensor of the molybdenum disulfide microsphere ordered array according to claim 1, characterized in that, The specific operation steps of S30 are as follows: S301, Put MoO3 powder into the reactor, invert the synthesized SiO2 microsphere template on the reactor, and place it in the high-temperature zone of the tube furnace; S302, Put sulfur powder into another reactor and place it at the edge of the tube furnace near the low-temperature zone. When the temperature rise ends and the reaction starts, push the reactor containing sulfur powder to the low-temperature zone; S303, Introduce high-purity argon into the tube furnace at a rate of 15 sccm in volume flow, and slowly raise the temperatures of the high-temperature zone and the low-temperature zone to 670 - 690 °C and 250 - 300 °C respectively, and keep the temperature for reaction for 20 - 60 min; S304, After the reaction in step S303 is completed, let the tube furnace cool naturally to room temperature to prepare the MoS2 microsphere array sensing layer.

3. The preparation method of the optoelectronic gas sensor of the molybdenum disulfide microsphere ordered array according to claim 2, characterized in that, In step S302, the reactor containing sulfur powder is first placed at the edge of the tube furnace near the low-temperature zone, and when the temperature rise ends and the reaction starts, push the reactor containing sulfur powder to the low-temperature zone.

4. The preparation method of the optoelectronic gas sensor of the molybdenum disulfide microsphere ordered array according to claim 1, characterized in that, Both the drain electrode and the source electrode are Au electrodes, and the metal wire is an Au wire.

5. The preparation method of the photoelectric gas sensor of the molybdenum disulfide microsphere ordered array according to claim 1, characterized in that The substrate is one or more of SiO2 / Si substrate, sapphire substrate or mica substrate.

6. The preparation method of the photoelectric gas sensor of the molybdenum disulfide microsphere ordered array according to claim 1, characterized in that, An ultraviolet light source is further arranged above the chamber.

7. An optoelectronic gas sensor with an ordered array of molybdenum disulfide microspheres, characterized in that: It is prepared by the method described in any one of claims 1 to 6.

8. Application of a photoelectric gas sensor of an ordered array of molybdenum disulfide microspheres as described in claim 7 in the detection of triethylamine gas.

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