High-entropy metal sulfide, preparation method thereof and nitrogen dioxide gas sensor
Through the development and preparation of high-entropy metal sulfides, the problem of low sensitivity of traditional nitrogen dioxide gas sensors is solved, and rapid response and high sensitivity monitoring are achieved to nitrogen dioxide, which significantly improves the sensor performance.
Patent Information
- Application Number
- CN202411476306.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-22
- Publication Date
- 2025-01-17
AI Technical Summary
Traditional nitrogen dioxide gas sensors have low sensitivity and long response time, making it difficult to effectively monitor trace nitrogen dioxide pollution.
Develop a high-entropy metal sulfide containing tungsten, molybdenum, zinc, tin and chromium elements, prepared by hydrothermal reaction to form nanoparticles or nanosheet-like materials with single-phase structures, enhance catalytic activity and conductivity, and improve the two-phase Nitric oxide sensitivity.
Fast response and high sensitivity monitoring to nitrogen dioxide are achieved, and trace amounts of nitrogen dioxide can be detected at room temperature, significantly improving the performance of the sensor.
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Figure CN119320172A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of sensor technology, and in particular to a high entropy metal sulfide and a preparation method thereof, and a nitrogen dioxide gas sensor. Background Art
[0002] In some industrially developed cities, factories, power plants and other industrial facilities burn fossil fuels during the production process, which will produce a large amount of nitrogen dioxide. In addition, due to the high number of motor vehicles in cities and heavy traffic, automobile exhaust emissions are also a major disaster area for nitrogen dioxide emissions. Although in recent years, as countries pay more attention to environmental protection, the nitrogen dioxide pollution situation in some areas has improved, but globally, nitrogen dioxide pollution is still an important environmental problem that endangers human health.
[0003] Therefore, monitoring nitrogen dioxide through high-performance nitrogen dioxide gas sensors is an important part of controlling nitrogen dioxide pollution, but traditional nitrogen dioxide gas sensors have the problem of low sensitivity. Summary of the invention
[0004] Based on this, it is necessary to provide a high entropy metal sulfide and a preparation method thereof and a nitrogen dioxide gas sensor that can enhance the sensitivity to nitrogen dioxide.
[0005] In a first aspect of the present application, a high entropy metal sulfide is provided, wherein the metal elements in the high entropy metal sulfide include tungsten, molybdenum, zinc, tin and chromium; and the high entropy metal sulfide has a single-phase structure.
[0006] The metal elements of the high entropy metal sulfide of the present application include tungsten, molybdenum, zinc, tin and chromium, and the elements form a highly disordered atomic arrangement, but still maintain a single-phase structure and a relatively uniform element distribution; the five metal elements of the high entropy metal sulfide cooperate with each other to produce a synergistic effect, thereby enhancing the catalytic activity of the high entropy metal sulfide, thereby promoting the adsorption and reaction rate of gas molecules, and further improving the sensitivity to nitrogen dioxide; in addition, the five metal elements cooperate with each other to enrich the electronic state of the high entropy metal sulfide, improve the conductivity of the high entropy metal sulfide, so that its electrical conductivity is improved, thereby increasing the sensing ability to nitrogen dioxide gas; the high entropy metal sulfide of the present application unexpectedly shows a high sensitivity to nitrogen dioxide gas, achieving a faster response speed and higher monitoring sensitivity to nitrogen dioxide.
[0007] The metal elements of the high-entropy metal sulfide of the present application are combined with sulfur in the form of covalent bonds or ionic bonds to form a stable sulfide structure. Moreover, due to the high mixing entropy of the system, the entropy effect helps to prevent phase separation and enhance the phase stability of the material. Even if the five elements have different chemical and physical properties, they can coexist in a stable phase without forming a complex multiphase structure, thereby making the high-entropy metal sulfide of the present application have high chemical stability and high thermal stability.
[0008] The present application expands the use of high entropy metal sulfides. The high entropy metal sulfides of the present application show excellent use effects in the field of nitrogen dioxide monitoring and can respond quickly to trace amounts of nitrogen dioxide at room temperature.
[0009] In some embodiments, the molar ratio of the tungsten element, the molybdenum element, the zinc element, the tin element and the chromium element is 1:1~2:0.5~2:0.5~2:0.5~2.
[0010] In some embodiments, the molar ratio of the tungsten element, the molybdenum element, the zinc element, the tin element, the chromium element and the sulfur element is 1:1~2:0.5~2:0.5~2:0.5~2:9.5~11.
[0011] In some embodiments, the chemical formula of the high entropy metal sulfide is: 0.1 Mo 0.2 Zn 0.1- 0.2 Sn 0.1-0.2 Cd 0.1-0.2 )S 0.95-1.1 .
[0012] In some embodiments, the chemical formula of the high entropy metal sulfide is (W 0.1 Mo 0.2 Zn 0.2 Sn 0.05 Cd 0.05 )S 0.95 ,(W 0.1 Mo 0.2 Zn 0.05 Sn 0.2 Cd 0.05 )S 1.1 ,(W 0.1 Mo 0.2 Zn 0.05 Sn 0.05 Cd 0.2 )S 0.95 or (W 0.1 Mo 0.2 Zn 0.1 Sn 0.1 Cd 0.1 )S 1.
[0013] In some embodiments, the high entropy metal sulfide is in the form of nanoparticles with an average particle size of 100 nm to 300 nm.
[0014] In some embodiments, the high entropy metal sulfide is in the form of nanosheets with a lateral size of 200nm to 400nm.
[0015] The second aspect of the present application provides a method for preparing the high entropy metal sulfide as described in the first aspect, comprising the following steps:
[0016] The organic sulfur-nitrogen compound, a tungsten source, a molybdenum source, a zinc source, a tin source and a chromium source are dissolved in a solvent and subjected to a hydrothermal reaction to obtain the high entropy metal sulfide.
[0017] In some embodiments, the temperature of the hydrothermal reaction is 150° C. to 200° C., and the time of the hydrothermal reaction is 12 h to 24 h.
[0018] In some embodiments, the solvent is one or more of water, N, N-dimethylformamide, methanol, ethanol and acetone.
[0019] In some of the embodiments, after the hydrothermal reaction step and before the high entropy metal sulfide is obtained, a step of drying the product of the hydrothermal reaction is also included, and the conditions of the drying step include: drying at a temperature of 45°C to 55°C for 20h to 30h.
[0020] The third aspect of the present application provides a high entropy metal sulfide coating, comprising the high entropy metal sulfide as described in the first aspect, or the high entropy metal sulfide prepared by the preparation method of the high entropy metal sulfide as described in the second aspect.
[0021] The fourth aspect of the present application provides a nitrogen dioxide gas sensor, comprising a substrate and interdigital electrodes and a nitrogen dioxide gas-sensitive coating sequentially stacked on the substrate, wherein the nitrogen dioxide gas-sensitive coating comprises the high entropy metal sulfide as described in the first aspect, or comprises a high entropy metal sulfide prepared by the preparation method of the high entropy metal sulfide as described in the second aspect. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Figure 1 This is a scanning electron microscope image of the high entropy metal sulfide prepared in Example 1.
[0023] Figure 2 This is the response curve of the high entropy metal sulfide prepared in Example 1 to different concentrations of nitrogen dioxide at room temperature.
[0024] Figure 3This is a scanning electron microscope image of the high entropy metal sulfide prepared in Example 2.
[0025] Figure 4 This is the response curve of the high entropy metal sulfide prepared in Example 2 to 1 ppm nitrogen dioxide at room temperature.
[0026] Figure 5 This is a scanning electron microscope image of the high entropy metal sulfide prepared in Example 3.
[0027] Figure 6 This is the response curve of the high entropy metal sulfide prepared in Example 3 to 1 ppm nitrogen dioxide at room temperature.
[0028] Figure 7 This is a scanning electron microscope image of the high entropy metal sulfide prepared in Example 4.
[0029] Figure 8 This is the response curve of the high entropy metal sulfide prepared in Example 4 to 1 ppm nitrogen dioxide at room temperature. DETAILED DESCRIPTION
[0030] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.
[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.
[0032] Nitrogen dioxide pollution in the atmosphere is harmful to human health. Monitoring nitrogen dioxide is an important part of controlling nitrogen dioxide pollution. In many cases, nitrogen dioxide gas sensors are used to identify nitrogen dioxide in a timely manner. Traditional nitrogen dioxide gas sensors usually use semiconductor metal oxide materials as gas-sensitive materials. Among them, tin dioxide and tungsten trioxide are widely used, but their sensitivity to nitrogen dioxide gas is not high enough, the response time is long, and there is a lag problem. Some researchers have also tried to use the composite form of organic and inorganic materials, such as reduced graphene oxide and double-layer porphyrin phthalocyanine complexes, but the preparation process of such materials is complicated, and the sensitivity and selectivity need to be improved.
[0033] Based on this, the first aspect of the present application provides a high entropy metal sulfide, wherein the metal elements in the high entropy metal sulfide include tungsten, molybdenum, zinc, tin and chromium; and the high entropy metal sulfide has a single-phase structure.
[0034] The metal elements of the high entropy metal sulfide of the present application include tungsten, molybdenum, zinc, tin and chromium, and the elements form a highly disordered atomic arrangement, but still maintain a single-phase structure and a relatively uniform element distribution; the five metal elements of the high entropy metal sulfide cooperate with each other to produce a synergistic effect, thereby enhancing the catalytic activity of the high entropy metal sulfide, thereby promoting the adsorption and reaction rate of gas molecules, and further improving the sensitivity to nitrogen dioxide; in addition, the five metal elements cooperate with each other to enrich the electronic state of the high entropy metal sulfide, improve the conductivity of the high entropy metal sulfide, so that its electrical conductivity is improved, thereby increasing the sensing ability to nitrogen dioxide gas; the high entropy metal sulfide of the present application unexpectedly shows a high sensitivity to nitrogen dioxide gas, achieving a faster response speed and higher monitoring sensitivity to nitrogen dioxide.
[0035] The metal elements of the high-entropy metal sulfide of the present application are combined with sulfur in the form of covalent bonds or ionic bonds to form a stable sulfide structure. Moreover, due to the high mixing entropy of the system, the entropy effect helps to prevent phase separation and enhance the phase stability of the material. Even if the five elements have different chemical and physical properties, they can coexist in a stable phase without forming a complex multiphase structure, thereby making the high-entropy metal sulfide of the present application have high chemical stability and high thermal stability.
[0036] The present application expands the use of high entropy metal sulfides. The high entropy metal sulfides of the present application show excellent use effects in the field of nitrogen dioxide monitoring and can respond quickly to trace amounts of nitrogen dioxide at room temperature.
[0037] In some embodiments, the molar ratio of the tungsten element, molybdenum element, zinc element, tin element and chromium element is 1: 1~2: 0.5~2: 0.5~2: 0.5~2. The high entropy metal sulfide with the five metal elements at this molar ratio has excellent catalytic activity and electrical conductivity, responds more quickly and sensitively to nitrogen dioxide gas, and has a strong response to 1ppm nitrogen dioxide gas.
[0038] Furthermore, the molar ratio of the tungsten element, molybdenum element, zinc element, tin element and chromium element is 1: 1~2: 1~2: 0.5~1: 0.5~1. The high entropy metal sulfide of the five metal elements at this molar ratio responds particularly strongly to nitrogen dioxide gas, with a higher response value, and the detection limit can reach 500 ppb.
[0039] The molar ratio of the tungsten element, molybdenum element, zinc element, tin element and chromium element is preferably 1:2:1:1:1, 1:2:2:0.5:0.5, 1:2:0.5:2:0.5 or 1:2:0.5:0.5:2.
[0040] In some embodiments, the molar ratio of the tungsten element, the molybdenum element, the zinc element, the tin element, the chromium element and the sulfur element is 1:1~2:0.5~2:0.5~2:0.5~2:9.5~11.
[0041] Furthermore, the molar ratio of the tungsten element, molybdenum element, zinc element, tin element, chromium element and sulfur element is preferably one of 1:2:1:1:1:10, 1:2:2:0.5:0.5:9.5, 1:2:0.5:2:0.5:11 or 1:2:0.5:0.5:2:9.5.
[0042] In some embodiments, the chemical formula of the high entropy metal sulfide is: 0.1 Mo 0.2 Zn 0.1- 0.2 Sn 0.1-0.2 Cd 0.1-0.2 )S 0.95-1.1 .
[0043] In some embodiments, the chemical formula of the high entropy metal sulfide is (W 0.1 Mo 0.2 Zn 0.2 Sn 0.05 Cd 0.05 )S 0.95 ,(W 0.1 Mo 0.2 Zn 0.05 Sn 0.2 Cd 0.05 )S 1.1 ,(W 0.1 Mo 0.2 Zn 0.05 Sn 0.05 Cd 0.2 )S 0.95 or (W 0.1 Mo 0.2 Zn 0.1 Sn 0.1 Cd 0.1 )S 1 .
[0044] In some embodiments, the high entropy metal sulfide is in the form of nanoparticles with an average particle size of 100 nm to 300 nm.
[0045] In some embodiments, the high entropy metal sulfide is in the form of nanosheets with a lateral size of 200nm to 400nm.
[0046] The second aspect of the present application provides a method for preparing the high entropy metal sulfide as described in the first aspect, comprising the following steps: dissolving an organic sulfur-nitrogen compound, a tungsten source, a molybdenum source, a zinc source, a tin source and a chromium source in a solvent, and conducting a hydrothermal reaction to obtain the high entropy metal sulfide.
[0047] The tungsten source, molybdenum source, zinc source, tin source and chromium source are all soluble in the solvent.
[0048] In some embodiments, the raw materials for preparing the high entropy sulfide include organic sulfur-nitrogen compounds, tungstates, molybdates, zinc salts, tin salts and chromium salts.
[0049] In some embodiments, the organic sulfur-nitrogen compound is one or more of thiourea, thiazole, sulfadiazine, thioacetamide and polybenzothiazole, preferably thiourea.
[0050] In some embodiments, the tungstate is one or more of sodium tungstate dihydrate, ammonium tungstate, calcium tungstate, ferrous tungstate and magnesium tungstate, preferably sodium tungstate dihydrate.
[0051] In some embodiments, the molybdate is one or more of ammonium molybdate tetrahydrate, sodium molybdate and calcium molybdate, preferably ammonium molybdate tetrahydrate.
[0052] In some embodiments, the zinc salt is one or more of zinc chloride, zinc sulfate and zinc nitrate, preferably zinc chloride.
[0053] In some embodiments, the tin salt is tin dichloride pentahydrate, stannous sulfate, tin nitrate and sodium stannate. Preferably, tin dichloride pentahydrate is used.
[0054] In some embodiments, the chromium salt is chromium chloride, chromium nitrate, chromium sulfate, sodium chromate, sodium dichromate and potassium dichromate. Chromium chloride is preferably used.
[0055] In some embodiments, the raw materials for preparing the high entropy sulfide include thiourea, sodium tungstate dihydrate, ammonium molybdate tetrahydrate, zinc chloride, tin dichloride pentahydrate and chromium chloride.
[0056] In some embodiments, the temperature of the hydrothermal reaction is 150°C to 200°C, preferably 180°C to 200°C; the time of the hydrothermal reaction is 12h to 24h, preferably 18h to 24h.
[0057] In some embodiments, the solvent is one or more of deionized water, N, N-dimethylformamide, methanol, ethanol and acetone.
[0058] In some embodiments, magnetic stirring or mechanical stirring is used during the hydrothermal reaction, with a stirring speed of 600 to 1500 rpm and a stirring time of 1 to 3 hours.
[0059] In some of the embodiments, after the hydrothermal reaction step and before the high entropy metal sulfide is obtained, a step of drying the product of the hydrothermal reaction is also included, and the conditions of the drying step include: drying at a temperature of 45°C to 55°C for 20h to 30h.
[0060] Furthermore, the hydrothermal reaction product is cleaned by centrifugation and then dried in a vacuum oven.
[0061] Furthermore, the cleaning solvent of the centrifugal cleaning is one of deionized water, ethanol or a mixed solvent made of deionized water and ethanol, the centrifugal speed of the centrifugal cleaning is 5000-8000 rpm, and the time of the centrifugal cleaning is 5-30 minutes.
[0062] The third aspect of the present application provides a high entropy metal sulfide coating, comprising the high entropy metal sulfide as described in the first aspect, or the high entropy metal sulfide prepared by the preparation method of the high entropy metal sulfide as described in the second aspect.
[0063] The fourth aspect of the present application provides a nitrogen dioxide gas sensor, comprising a substrate and interdigital electrodes and a nitrogen dioxide gas-sensitive coating sequentially stacked on the substrate, wherein the nitrogen dioxide gas-sensitive coating comprises the high-entropy sulfide as described in the first aspect, or comprises a high-entropy sulfide prepared by the preparation method of the high-entropy sulfide as described in the second aspect.
[0064] Furthermore, the substrate of the nitrogen dioxide gas sensor is one of a silicon substrate, a polymer substrate, a ceramic substrate or a sapphire substrate.
[0065] Furthermore, the interdigital electrodes of the nitrogen dioxide gas sensor are obtained by micromachining technology, the spacing between the positive and negative electrodes of the interdigital electrodes is 200 μm to 800 μm, and the spacing between two adjacent interdigital electrodes is 50 μm to 400 μm.
[0066] In some embodiments, the high entropy metal sulfide is prepared into a dispersion and then coated on the interdigital electrodes to form a nitrogen dioxide gas-sensitive coating.
[0067] Furthermore, the high entropy metal sulfide is added to a solvent at a concentration of 1 mg / L to 10 mg / L to prepare a dispersion.
[0068] Furthermore, the solvent in the dispersion can be one or more of deionized water, N, N-dimethylformamide, N, N-dimethylacetamide, methanol, ethanol and acetone. In order to make the high entropy metal sulfide dispersed evenly in the solvent, the dispersion can be treated with ultrasound at 50kHz to 100kHz for 2min to 20min.
[0069] The following are specific embodiments.
[0070] Example 1
[0071] 760.00 mg thiourea, 352.86 mg ammonium molybdate tetrahydrate, 329.00 mg sodium tungstate dihydrate, 136.00 mg zinc chloride, 350.00 mg tin dichloride pentahydrate, and 183.00 mg chromium chloride were weighed and added into 30 mL deionized water, and stirred at 1000 rpm for 1 hour using a stirring device to obtain a mixed solution; the mixed solution was transferred into a 50 mL hydrothermal reactor, and hydrothermally reacted at 200° C. for 24 hours. After the reactant was cooled, a black product was separated by centrifugation, and then washed three times with anhydrous ethanol. The washed product was placed in a vacuum oven and dried at a drying temperature of 50° C. for 24 hours to obtain a high entropy metal sulfide (W) with a molar ratio of tungsten, molybdenum, zinc, tin and chromium of 1:2:1:1:1. 0.1 Mo 0.2 Zn 0.1 Sn 0.1 Cd 0.1 )S 1 ;
[0072] The prepared high entropy metal sulfide was added into deionized water at a concentration of 1 mg / L, and ultrasonicated at 40 kHz for 10 minutes to uniformly disperse the high entropy metal sulfide to obtain a dispersion;
[0073] The interdigital electrodes were prepared by micromachining technology, the spacing between the positive and negative electrodes of the interdigital electrodes was controlled to be 700 μm, and the spacing between two adjacent interdigital electrodes was 200 μm. Then, 1 μL of the dispersion was dripped and coated on the surface of the interdigital electrodes to form a nitrogen dioxide gas-sensitive coating. The nitrogen dioxide gas-sensitive coating was vacuum dried at 60°C for 1 hour to obtain a nitrogen dioxide gas sensor.
[0074] Example 2
[0075] Example 2 is substantially the same as Example 1, except that the amounts of thiourea, ammonium molybdate tetrahydrate, sodium tungstate dihydrate, zinc chloride, tin dichloride pentahydrate, and chromium chloride are 722.00 mg, 352.86 mg, 329.00 mg, 272.00 mg, 175.00 mg, and 91.25 mg, respectively, and the molar ratio of tungsten, molybdenum, zinc, tin, and chromium in the obtained high entropy metal sulfide is 1:2:2:0.5:0.5. 0.1 Mo 0.2 Zn 0.2 Sn 0.05 Cd 0.05 )S 0.95 .
[0076] Example 3
[0077] Example 3 is substantially the same as Example 1, except that the amounts of thiourea, ammonium molybdate tetrahydrate, sodium tungstate dihydrate, zinc chloride, tin dichloride pentahydrate, and chromium chloride are 836.00 mg, 352.86 mg, 329.00 mg, 68.00 mg, 700.00 mg, and 91.50 mg, respectively, and the molar ratio of tungsten, molybdenum, zinc, tin, and chromium in the obtained high entropy metal sulfide is 1:2:0.5:2:0.5. 0.1 Mo 0.2 Zn 0.05 Sn 0.2 Cd 0.05 )S 1.1 .
[0078] Example 4
[0079] Example 4 is substantially the same as Example 1, except that the amounts of thiourea, ammonium molybdate tetrahydrate, sodium tungstate dihydrate, zinc chloride, tin dichloride pentahydrate, and chromium chloride are 722.00 mg, 352.86 mg, 329.00 mg, 68.00 mg, 175.00 mg, and 366.00 mg, respectively, and the obtained high entropy metal sulfide has a molar ratio of tungsten element, molybdenum element, zinc element, tin element, and chromium element of 1:2:0.5:0.5:2. 0.1 Mo 0.2 Zn 0.05 Sn 0.05 Cd 0.2 )S 0.95 .
[0080] Comparative Example 1
[0081] Comparative Example 1 is substantially the same as Example 1, except that sodium tungstate dihydrate is omitted from the raw material for preparing the high entropy metal sulfide.
[0082] Comparison document 2
[0083] Comparative Example 2 is substantially the same as Example 1, except that ammonium molybdate tetrahydrate is omitted from the raw material for preparing the high entropy metal sulfide.
[0084] Comparative Example 3
[0085] Comparative Example 3 is substantially the same as Example 1, except that zinc chloride is omitted from the raw material for preparing the high entropy metal sulfide.
[0086] Comparative Example 4
[0087] Comparative Example 4 is substantially the same as Example 1, except that tin dichloride pentahydrate is omitted from the raw material for preparing the high entropy metal sulfide.
[0088] Comparative Example 5
[0089] Comparative Example 5 is substantially the same as Example 1, except that chromium chloride is omitted from the raw material for preparing high entropy metal sulfide.
[0090] Comparative Example 6
[0091] Comparative Example 6 is substantially the same as Example 1, except that an equal molar amount of lanthanum nitrate hexahydrate is used to replace sodium tungstate dihydrate.
[0092] Comparative Example 7
[0093] Comparative Example 7 is substantially the same as Example 1, except that an equimolar amount of sodium chloropalladate is used to replace ammonium molybdate tetrahydrate.
[0094] Comparative Example 8
[0095] Comparative Example 8 is substantially the same as Example 1, except that an equimolar amount of nickel nitrate hexahydrate is used to replace zinc chloride.
[0096] Comparative Example 9
[0097] Comparative Example 9 is substantially the same as Example 1, except that tin dichloride pentahydrate is replaced by an equal molar amount of ferric chloride.
[0098] Comparative Example 10
[0099] Comparative Example 10 is substantially the same as Example 1, except that chromium chloride is replaced by an equal molar amount of manganese chloride.
[0100] Examples 1-4 and Comparative Examples 1-10 were subjected to a response sensitivity test to 1 ppm nitrogen dioxide gas at room temperature. The test results are shown in Table 1 below.
[0101] Among them, the test conditions for the response value of 1ppm nitrogen dioxide at room temperature are: the test system consists of a gas distribution system and a data acquisition system. The gas distribution system adjusts the ratio of the target gas and compressed air introduced into the test chamber through a mass flow controller (MFC), and then dilutes the target gas with a fixed nitrogen dioxide concentration to the concentration required for the test. The test process is as follows: first, the nitrogen dioxide gas sensor is placed in the test chamber, and the background gas (air) is continuously introduced into the chamber until the current curve of the nitrogen dioxide gas sensor is stable; then the background gas valve is closed, the valves of the target gas and the dilution gas (air) are opened, and the relative ratio of the two is controlled by MFC, so as to obtain the required concentration of mixed gas in the test chamber, and the mixture is continuously introduced for 30s; finally, the target gas valve is closed, the background gas valve is opened, and the background gas is continuously introduced to purge the test chamber until the nitrogen dioxide gas sensor returns to its initial state. When the target gas contacts the nitrogen dioxide gas-sensitive coating on the nitrogen dioxide gas sensor, the conductivity of the nitrogen dioxide gas-sensitive coating will change accordingly, and then it will be recorded in real time by the semiconductor tester (Agilent 4156C) and displayed on the computer. The response value of nitrogen dioxide is defined as Ig / Ia, where Ig and Ia represent the current values of the nitrogen dioxide gas sensor in the target gas and air, respectively.
[0102] Table 1
[0103]
[0104] As can be seen from Table 1 above, the high entropy metal sulfide containing five metal elements, namely tungsten, molybdenum, zinc, tin and chromium, is extremely sensitive to nitrogen dioxide gas, and the response value for 1ppm nitrogen dioxide at room temperature can be as high as 1.3. The nitrogen dioxide gas sensor made of this high entropy metal sulfide as a nitrogen dioxide gas-sensitive coating achieves a faster response speed and higher monitoring sensitivity to nitrogen dioxide. It can be seen from the data of Examples 1 to 4 that when the molar ratio of tungsten, molybdenum, zinc, tin and chromium is 1:1~2:0.5~2:0.5~2:0.5~2, the high entropy metal sulfide responds particularly quickly and sensitively to nitrogen dioxide gas, and has a strong response to 1ppm nitrogen dioxide gas. It can be seen from the data of Examples 1 and 2 that when the molar ratio of tungsten, molybdenum, zinc, tin and chromium is 1:1~2:1~2:0.5~1:0.5~1, the high entropy metal sulfide responds more strongly to nitrogen dioxide gas and has a higher response value.
[0105] from Figure 1 It can be seen that the high entropy metal sulfide with a molar ratio of 1:2:1:1:1 of tungsten, molybdenum, zinc, tin and chromium elements is in the form of nanoparticles. Figure 2It can be seen that with the increase of nitrogen dioxide concentration, the response value of the gas sensor gradually increases. The sensor has a strong response to 1 ppm nitrogen dioxide, which is 1.15, and the actual minimum detection limit is 0.5 ppm.
[0106] from Figure 3 It can be seen that the high entropy metal sulfide with a molar ratio of 1:2:2:0.5:0.5 of tungsten, molybdenum, zinc, tin and chromium elements presents a nanosheet shape. Figure 4 It can be seen that the molar ratio of tungsten, molybdenum, zinc, tin and chromium elements is 1:2:2:0.5:0.5. The response of high entropy metal sulfide to 1 ppm nitrogen dioxide at room temperature can be 1.30.
[0107] from Figure 5 It can be seen that the high entropy metal sulfide with a molar ratio of 1:2:0.5:2:0.5 for tungsten, molybdenum, zinc, tin and chromium elements is in the form of nanoparticles. Figure 6 It can be seen that the high entropy metal sulfide with a molar ratio of tungsten, molybdenum, zinc, tin and chromium elements of 1:2:0.5:2:0.5 can respond to 1 ppm nitrogen dioxide at room temperature with a response of 1.06.
[0108] from Figure 7 It can be seen that the high entropy metal sulfide with a molar ratio of 1:2:0.5:0.5:2 of tungsten, molybdenum, zinc, tin and chromium elements presents a nanosheet shape. Figure 8 It can be seen that the high entropy metal sulfide with a molar ratio of 1:2:0.5:0.5:2 of five elements, tungsten, molybdenum, zinc, tin and chromium, responds to 1 ppm nitrogen dioxide at room temperature with a response value of 1.03.
[0109] From the data of Comparative Examples 1 to 5, it can be seen that when any one of the elements tungsten, molybdenum, zinc, tin and chromium is missing, the obtained material has a poor performance in NO 2 The response to NO is significantly reduced, especially when the material lacks Zn. 2 No response. From the data of Comparative Examples 6 to 10, it can be seen that when the La, Pd, Ni, Fe, and Mn elements are used in equal molar amounts to replace the W, Mo, Zn, Sn, and Cd elements one by one, the response values are all lower than 1.01, and the effect of the present application cannot be achieved. Therefore, the five metal elements of the high entropy metal sulfide of the present application cooperate with each other to produce a synergistic effect, and together improve the sensitivity to nitrogen dioxide.
[0110] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0111] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.
Claims
1. A high entropy metal sulfide, characterized in that: The metal elements in the high entropy metal sulfide include tungsten, molybdenum, zinc, tin and chromium; and the high entropy metal sulfide is a single-phase structure.
2. The high entropy metal sulfide according to claim 1, characterized in that The molar ratio of the tungsten element, the molybdenum element, the zinc element, the tin element and the chromium element is 1:1-2:0.5-2:0.5-2:0.5-2.
3. The high entropy metal sulfide according to claim 1, characterized in that The molar ratio of the tungsten element, the molybdenum element, the zinc element, the tin element, the chromium element and the sulfur element is 1:1-2:0.5-2:0.5-2:0.5-2:9.5-11.
4. The high entropy metal sulfide according to claim 1, characterized in that The chemical formula of the high entropy metal sulfide is: 0.1 Mo 0.2 Zn 0.1-0.2 Sn 0.1-0.2 Cd 0.1-0.2 )S 0.95-1.1 .
5. The high entropy metal sulfide according to claim 1, characterized in that The chemical formula of the high entropy metal sulfide is (W 0.1 Mo 0.2 Zn 0.2 Sn 0.05 Cd 0.05 )S 0.95 ,(W 0.1 Mo 0.2 Zn 0.05 Sn 0.2 Cd 0.05 )S 1.1 ,(W 0.1 Mo 0.2 Zn 0.05 Sn 0.05 Cd 0.2 )S 0.95 or (W 0.1 Mo 0.2 Zn 0.1 Sn 0.1 Cd 0.1 )S1.
6. The high entropy metal sulfide according to any one of claims 1 to 5, characterized in that The high entropy metal sulfide is in the form of nanoparticles with an average particle size of 100nm to 300nm.
7. The high entropy metal sulfide according to any one of claims 1 to 5, characterized in that The high entropy metal sulfide is in the form of nanosheets with a lateral size of 200nm to 400nm.
8. A method for preparing a high entropy metal sulfide according to any one of claims 1 to 7, characterized in that: The following steps are involved: The organic sulfur-nitrogen compound, a tungsten source, a molybdenum source, a zinc source, a tin source and a chromium source are dissolved in a solvent and subjected to a hydrothermal reaction to obtain the high entropy metal sulfide.
9. The method for preparing high entropy metal sulfide according to claim 8, characterized in that: The temperature of the hydrothermal reaction is 150° C. to 200° C., and the time of the hydrothermal reaction is 12 h to 24 h.
10. The method for preparing high entropy metal sulfide according to claim 8, characterized in that: The solvent is one or more of water, N,N-dimethylformamide, methanol, ethanol and acetone.
11. The method for preparing high entropy metal sulfide according to claim 8, characterized in that: After the hydrothermal reaction step and before the high entropy metal sulfide is obtained, a drying step of the product of the hydrothermal reaction is also included, and the conditions of the drying step include: drying at a temperature of 45° C. to 55° C. for 20 h to 30 h.
12. A high entropy metal sulfide coating, characterized in that: The invention comprises the high entropy metal sulfide as described in any one of claims 1 to 7, or the high entropy metal sulfide prepared by the preparation method of the high entropy metal sulfide as described in any one of claims 8 to 11.
13. A nitrogen dioxide gas sensor, characterized in that: It comprises a substrate and interdigital electrodes and a nitrogen dioxide gas-sensitive coating sequentially stacked on the substrate, wherein the nitrogen dioxide gas-sensitive coating comprises the high-entropy metal sulfide as described in any one of claims 1 to 7, or comprises a high-entropy metal sulfide prepared by the preparation method of the high-entropy metal sulfide as described in any one of claims 8 to 11.