阅读说明：本技术 一种Ag修饰的In2O3复合材料及其制备方法、气敏元件及其应用 (Ag modified In2O3Composite material and preparation method thereof, gas sensor and application thereof ) 是由 王燕 张波 郭兰兰 张赛赛 曹建亮 孙雪雅 姚梦霞 张战营 于 2021-08-27 设计创作，主要内容包括：本发明属于气敏材料技术领域,具体涉及一种Ag修饰的In-(2)O-(3)复合材料及其制备方法、气敏元件及其应用。本发明的复合材料的制备方法包括以下步骤：将铟源溶解于混合溶液后进行加热反应,将反应产物离心洗涤、干燥、煅烧,得到In-(2)O-(3)微米球,将In-(2)O-(3)微米球分散于蒸馏水中,然后加入AgNO-(3)溶液和NaOH溶液,搅拌一定时间后,将产物固液分离,将所得固体洗涤并干燥得前驱体,将前驱体煅烧处理后,得到Ag修饰的In-(2)O-(3)复合材料。本发明的Ag修饰的In-(2)O-(3)复合材料具备较好的甲烷传感性能。对500ppm的甲烷气体的响应值高达27.4,最佳工作温度低至120℃,同时具备较好的选择性和可重复性。(The invention belongs to the technical field of gas-sensitive materials, and particularly relates to Ag modified In 2 O 3 Composite material and preparation method thereof, gas sensor and application thereof. The preparation method of the composite material comprises the following steps: dissolving an indium source In the mixed solution, heating for reaction, centrifugally washing, drying and calcining a reaction product to obtain In 2 O 3 Micro-spheres of In 2 O 3 Dispersing the microspheres in distilled water, and adding AgNO 3 Stirring the solution and NaOH solution for a certain time, carrying out solid-liquid separation on the product, washing and drying the obtained solid to obtain a precursor, and calcining the precursor to obtain Ag modified In 2 O 3 A composite material. Ag-modified In of the invention 2 O 3 The composite material has better methane sensing performance. The response value of the catalyst to 500ppm methane gas is as high as 27.4, the optimal working temperature is as low as 120 ℃, and the catalyst has better selectivity and repeatability.)

1. Ag modified In₂O₃A method for preparing a composite material, characterized in that the method comprises the steps of:

step S1, dissolving an indium source in a mixed solution composed of glycerol and isopropanol, and uniformly stirring to form a first solution;

step S2, heating the first solution for reaction, centrifugally washing, drying and calcining a reaction product to obtain In₂O₃Micro-balls;

step S3, mixing In₂O₃Dispersing the microspheres in distilled water, stirring, and adding AgNO₃Uniformly mixing the solution and a NaOH solution to obtain a second solution, continuously stirring the second solution, carrying out solid-liquid separation on a product, washing and drying the obtained solid to obtain a precursor;

step S4, calcining the precursor to obtain Ag modified In₂O₃A composite material.

2. Ag-modified In according to claim 1₂O₃A method for producing a composite material, characterized in that in step S1, the indium source is a water-soluble indium salt or a hydrate thereof;

preferably, the indium source is one or more of indium nitrate, indium chloride, indium sulfate, indium nitrate hydrate, indium chloride hydrate and indium sulfate hydrate.

3. Ag-modified In according to claim 1₂O₃The preparation method of the composite material is characterized in that in step S1, the mixed solution is prepared by mixing glycerol and isopropanol according to a volume ratio of 1: (3-4).

4. Ag-modified In according to claim 1₂O₃The preparation method of the composite material is characterized in that in step S2, the heating reaction is: transferring the first solution into a high-pressure reaction kettle, and then reacting at the constant temperature of 175-185 ℃ for 55-65 min;

preferably, in step S2, the calcination is performed in an air atmosphere at 300-400 ℃ for 2-4 h.

5. Ag-modified In according to claim 1₂O₃The method for producing a composite material is characterized in that, in step S3, AgNO₃The molar concentration ratio of the solution to the NaOH solution is 3: (18-21) wherein AgNO₃The molar concentration of the solution is 0.03M;

preferably, AgNO per 20mL of distilled water₃The total volume of the solution and the NaOH solution is 1-5 mL;

more preferably, the addition amount of Ag is: the atomic molar ratio of Ag to In is 10% or less;

more preferably, in step S3, the second solution is continuously stirred for 4-6 hours.

6. Ag-modified In according to claim 1₂O₃The method for preparing the composite material is characterized in that in step S4, the calcination treatment comprises the following steps: calcining the mixture for 55 to 65min at 340 to 360 ℃ in an air atmosphere.

7. In modified with Ag according to any one of claims 1 to 6₂O₃Ag modified In prepared by preparation method of composite material₂O₃A composite material.

8. Ag modified In₂O₃The gas sensor is characterized In that the Ag modified In₂O₃The preparation method of the gas sensor comprises the following steps:

step one, modifying the Ag of claim 7 In₂O₃Mixing the composite material with a solvent, and grinding to obtain viscous slurry;

step two, coating the viscous slurry on the surface of a substrate, drying and aging to obtain the Ag modified In₂O₃A gas sensor.

9. Ag-modified In according to claim 8₂O₃The gas sensor is characterized in that in the first step, the solvent is distilled water, absolute ethyl alcohol or terpineol;

preferably, every 50-100 mg of Ag modified In₂O₃The volume of the solvent corresponding to the composite material is 0.5-3 mL.

10. Ag-modified In according to claim 8 or 9₂O₃The application of the gas sensor in a methane sensor.

Technical Field

The invention belongs to the technical field of gas-sensitive materials, and particularly relates to Ag modified In₂O₃Composite material and preparation method thereof, gas sensor and application thereof.

Background

Methane is a combustible gas with neither smell nor color, and is the main component of natural gas, methane and well gas of coal mines. Methane can be used as fuel, such as natural gas and coal gas, in civil and industrial applications, and also can be used as chemical raw material for producing acetylene, hydrogen, synthetic ammonia, carbon black and the like. Methane is basically nontoxic to people, but when the methane in the air reaches 25-30%, headache, dizziness, hypodynamia, inattention, acceleration of respiration and heartbeat and ataxia can be caused, and if the methane is not away in time, suffocation death can be caused. The mixture of methane and air can form explosive mixture, and the mixture has danger of combustion and explosion when meeting heat sources, open fire and the like, and is dangerous gas causing serious accidents in coal mines. In addition, methane is a powerful greenhouse gas with a global warming potential of around 28 times that of carbon dioxide. Therefore, it is necessary to develop a reliable and relatively inexpensive methane gas sensor for detecting the concentration of methane in the air.

In the research of gas sensors, one of the main directions is to rely on sensitive materials such as SnO in a gaseous environment₂、ZnO、TiO₂、In₂O₃The metal oxide semiconductors have the advantages of high sensitivity, quick response, low cost, good stability and the likeTherefore, the research of using the material as a gas sensitive material has been receiving much attention. The gas sensitive material with excellent performance is often doped with noble metals such as Pt, Pd, Au and the like, however, the doped noble metal materials have poor gas sensitive performance such as sensitivity and the like, the synthesis cost is high, and the gas sensitive material is difficult to be widely applied in practice.

Therefore, there is a need to provide an improved solution to the above-mentioned deficiencies of the prior art.

Disclosure of Invention

The invention aims to provide Ag modified In₂O₃The composite material, the preparation method thereof, the gas sensor and the application thereof solve the problems of low gas sensitive material, high working temperature, high cost and difficult stable use of the existing gas sensitive material.

In order to achieve the purpose, the invention provides the following technical scheme:

ag modified In₂O₃A method of making a composite material, the method comprising the steps of:

step S1, dissolving an indium source in a mixed solution composed of glycerol and isopropanol, and uniformly stirring to form a first solution;

step S2, heating the first solution for reaction, centrifugally washing, drying and calcining a reaction product to obtain In₂O₃Micro-balls;

step S3, mixing In₂O₃Dispersing the microspheres in distilled water, stirring, and adding AgNO₃Uniformly mixing the solution and a NaOH solution to obtain a second solution, continuously stirring the second solution, carrying out solid-liquid separation on a product, washing and drying the obtained solid to obtain a precursor;

step S4, calcining the precursor to obtain Ag modified In₂O₃A composite material.

In the above production method, preferably, in step S1, the indium source is a water-soluble indium salt and a hydrate thereof.

In the above production method, the indium source is preferably one or two or more selected from indium nitrate, indium chloride, indium sulfate, indium nitrate hydrate, indium chloride hydrate, and indium sulfate hydrate.

In the above production method, preferably, in step S1, the mixed solution is prepared from glycerol and isopropanol in a volume ratio of 1: (3-4).

In the above preparation method, preferably, in step S2, the heating reaction is: and transferring the first solution into a high-pressure reaction kettle, and then reacting at the constant temperature of 175-185 ℃ for 55-65 min.

In the preparation method, in step S2, the calcination is preferably performed in an air atmosphere at 300 to 400 ℃ for 2 to 4 hours.

In the above production method, preferably, in step S3, AgNO₃The molar concentration ratio of the solution to the NaOH solution is 3: (18-21) wherein AgNO₃The molar concentration of the solution was 0.03M.

In the above preparation method, preferably, AgNO is used per 20mL of distilled water₃The total volume of the solution and the NaOH solution is 1-5 mL.

In the above preparation method, more preferably, the addition amount of Ag is: the atomic molar ratio of Ag to In is 10% or less.

In the preparation method, the second solution is preferably stirred for 4 to 6 hours in step S3.

In the above preparation method, preferably, in step S4, the calcination treatment is: calcining the mixture for 55 to 65min at 340 to 360 ℃ in an air atmosphere.

The present invention also provides In modified with the above Ag₂O₃Ag modified In prepared by preparation method of composite material₂O₃A composite material.

The invention also provides Ag modified In₂O₃Gas sensor, the Ag-modified In₂O₃The preparation method of the gas sensor comprises the following steps:

step one, modifying the Ag modified In₂O₃Mixing the composite material with a solvent, and grinding to obtain viscous slurry;

step two, coating the viscous slurry on the surface of a substrate, drying and aging to obtain the Ag modified In₂O₃A gas sensor.

For the above Ag-modified In₂O₃The gas sensor, preferably, in step one, the solvent is distilled water, absolute ethyl alcohol or terpineol.

For the above Ag-modified In₂O₃Gas sensor, preferably, In modified with Ag per 50-100 mg of Ag₂O₃The volume of the solvent corresponding to the composite material is 0.5-3 mL.

The present invention also provides the Ag-modified In₂O₃The application of the gas sensor in a methane sensor.

Has the advantages that:

(1) ag-modified In of the invention₂O₃The composite material has better methane sensing performance. The response value of the catalyst to 500ppm methane gas is as high as 27.4, the optimal working temperature is as low as 120 ℃, and the catalyst has better selectivity and repeatability.

(2) In the present invention₂O₃The micron spheres are used as semiconductor materials, have uniform appearance and are easy to diffuse methane gas. In₂O₃On the basis of the micro-spheres, Ag is used as a precious metal for modification, so that the cost is lower than that of Au, Pd, Pt and other precious metals, and the micro-spheres have great market application potential.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and together with the description serve to explain the invention and not to limit the invention. Wherein

FIG. 1 shows Ag-modified In prepared In an example of the present invention₂O₃XRD patterns of the composite materials, In the patterns, five curves of a, b, c, d and e are respectively the same as the Ag modified In examples 1, 2, 3, 4 and 5₂O₃The composite material corresponds;

FIG. 2 shows Ag-modified In prepared In accordance with an embodiment of the present invention₂O₃Response of the gas sensor to 500ppm methane as a function of temperature;

FIG. 3 shows examples 1,Ag modified In prepared In example 3₂O₃Gas sensor for different concentrations of CH₄Dynamic response recovery curve of gas;

FIG. 4 shows Ag-modified In prepared In examples 1 and 3 of the present invention₂O₃The gas sensor is used for testing the selectivity of different gases;

FIG. 5 shows Ag-modified In prepared In example 3 of the present invention₂O₃Cyclability test of the gas sensor to 300ppm methane.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments that can be derived by one of ordinary skill in the art from the embodiments given herein are intended to be within the scope of the present invention.

The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings. It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.

The invention provides Ag modified In₂O₃The composite material is used for constructing a gas sensor, and then a methane gas sensor with high sensitivity, low working temperature, low cost and stability is further constructed.

Ag-modified In of the invention₂O₃In the composite material, In₂O₃Is In₂O₃In assembled from nanoparticles₂O₃And (4) micro-spheres.

Ag-modified In of the invention₂O₃The preparation method of the composite material comprises the following steps:

s1, dissolving an indium source in a mixed solution composed of glycerol and isopropanol, and violently and uniformly stirring to form a first solution;

s2, carrying out high-temperature reaction (namely heating reaction) on the first solution, centrifugally washing, drying and calcining a reaction product to obtain In₂O₃Micro-balls;

s3, mixing In₂O₃Dispersing the microspheres in distilled water, stirring, and adding AgNO₃Uniformly mixing the solution and a NaOH solution to obtain a second solution, continuously stirring the second solution for a certain time (the stirring is carried out at room temperature, and the certain time can be 4-6 h, such as 4h, 5h or 6h), carrying out solid-liquid separation (such as centrifugation) on a product, washing the obtained solid and drying to obtain a precursor;

s4, calcining the precursor to obtain Ag modified In₂O₃A composite material.

In step S1, the indium source is a water-soluble indium salt or a hydrate thereof, such as one or more of indium nitrate, indium chloride, indium sulfate, indium nitrate hydrate, indium chloride hydrate, and indium sulfate hydrate.

In step S1, the mixed solution is prepared by mixing glycerol and isopropanol in a volume ratio of 1: (3-4), for example, the volume ratio is 1: 3. 1: 3.2, 1: 3.4, 1: 3.6, 1: 3.8 or 1: 4.

in step S2, the high temperature reaction is that the first solution is moved into a high pressure reactor, and then placed in an oven to react at 175-185 ℃ (such as 175 ℃, 177 ℃, 179 ℃, 180 ℃, 182 ℃ or 185 ℃) for 55-65 min (such as 55min, 57min, 59min, 60min, 63min or 65 min).

In step S2, the calcination is: the solid is placed in a muffle furnace and calcined for 2-4 h (2h, 2.5h, 3h, 3.5h or 4h) in an air atmosphere at 300-400 ℃ (for example, 300 ℃, 320 ℃, 340 ℃, 350 ℃, 360 ℃, 380 ℃ or 400 ℃).

In step S3, AgNO₃The molar concentration ratio of the solution to the NaOH solution is 3: (18-21) (e.g., 3: 18, 3: 19, 3: 20 or 3: 21), wherein AgNO₃The molar concentration of the solution is 0.03M; AgNO for every 20mL of distilled water₃The total volume of the solution and the NaOH solution is 1-5 mL (e.g., 1mL, 2mL, 3mL, 4mL, or 5 mL).

In step S3, indium source is used as In source, AgNO₃As the Ag source, the addition amount of Ag is as follows: the atomic molar ratio of Ag to In is 10% or less (i.e., the atomic molar ratio of Ag to In is greater than 0 but not greater than 10%), for example, 2%, 4%, or,6%, 8% or 10%. In comparison, the present inventors also investigated the properties of the resulting material when the atomic molar ratio of Ag to In was 0%.

In step S4, the calcination treatment is performed in an air atmosphere at 340-360 deg.C (e.g., 340 deg.C, 345 deg.C, 350 deg.C, 355 deg.C or 360 deg.C) for 55-65 min (e.g., 55min, 57min, 59min, 60min, 63min or 65 min).

Ag-modified In of the invention₂O₃The preparation method of the gas sensor comprises the following steps:

step one, 50-100 mg (for example, 50mg, 60mg, 70mg, 80mg, 90mg or 100mg) of Ag modified In₂O₃Mixing the composite material powder with 0.5-3 mL (such as 0.5mL, 1mL or 3mL) of solvent in a mortar, and grinding into viscous slurry; the solvent is distilled water or absolute ethyl alcohol or terpineol;

step two, dipping the viscous slurry by a brush to uniformly coat the viscous slurry on Al with Ag-Pd crossed electrodes₂O₃Drying the surface of the substrate In an oven, and aging In an air-sensitive test bench to obtain Ag-modified In₂O₃A gas sensor.

The invention relates to Ag modified In₂O₃The application of the gas sensitive element in the aspect of a methane sensor can improve the detection sensitivity of methane gas, reduce the working temperature, reduce the cost and ensure the stable operation of equipment.

Ag-modified In of the invention₂O₃Detection performance of gas sensor on methane and reported In₂O₃The gas sensing performance of the base gas sensor is compared in table 1 below.

TABLE 1 gas-sensitive Performance comparison Table

The present invention will be further described with reference to the following examples.

Example 1

The material of this example was prepared without Ag, i.e., according to an atomic molar ratio of Ag to In of 0.0%, and the preparation method specifically included the following steps:

s1, mixing 0.6g In (NO)₃)₃·4.5H₂Dissolving O in a mixed solution of 16mL of glycerol and 60mL of isopropanol, and violently stirring for 30min to form a first solution;

s2, transferring the first solution into a high-pressure reaction kettle, reacting for 1h at a constant temperature of 180 ℃ In an oven, alternately washing and centrifuging for three times by using deionized water and alcohol, collecting precipitates (after the reaction is finished, adding deionized water into the obtained product system, shaking up, centrifuging, taking the lower precipitates, then replacing the deionized water with alcohol, repeating the process, recording the process as washing and centrifuging for one time, performing the process for three times, wherein the washing and centrifuging processes In other embodiments are the same and are not repeated), drying overnight at 60 ℃ In the oven, and calcining for 3h at 350 ℃ In a muffle furnace to obtain In₂O₃Micro-spheres, 0.0 at.% Ag/In₂O₃。

Example 2

Ag-modified In of this example₂O₃The composite material is prepared according to the atomic molar ratio of Ag to In of 4.0 percent, and the preparation method specifically comprises the following steps:

s1, mixing 0.4g In (NO)₃)₃·4.5H₂Dissolving O in a mixed solution of 15mL of glycerol and 60mL of isopropanol, and violently stirring for 30min to form a first solution;

s2, transferring the first solution into a high-pressure reaction kettle, reacting for 1h In an oven at a constant temperature of 180 ℃, alternately washing and centrifuging for three times by using deionized water and alcohol, collecting precipitate, drying for 24h In the oven at 60 ℃, and calcining for 3h In a muffle furnace at 350 ℃ to obtain In₂O₃Micro-balls;

s3, adding 0.2mmol of In₂O₃Corresponding mass of In₂O₃The microspheres were dispersed in 20mL distilled water, stirred well and then 0.53mL 0.03M AgNO was added₃And 0.53mL of 0.2M NaOH solution, uniformly mixing to obtain a second solution, continuously stirring the second solution for 5 hours, centrifuging a product, and washing and drying the obtained solid to obtain a precursor;

S4calcining the precursor In a muffle furnace at 350 ℃ for 1h to obtain 4% Ag modified In₂O₃Composite material, as 4.0 at.% Ag/In₂O₃。

Ag-modified In of this example₂O₃The preparation method of the gas sensor comprises the following steps:

step one, 50mg of Ag modified In₂O₃The composite material was mixed with 0.5mL of distilled water in a mortar and ground into a viscous slurry;

step two, dipping the viscous slurry by a brush to uniformly coat the viscous slurry on Al with Ag-Pd crossed electrodes₂O₃Drying the surface of the substrate In an oven, aging In a gas sensitive test bench at 140 deg.C for 48h to obtain Ag modified In₂O₃A gas sensor.

Example 3

Ag-modified In of this example₂O₃The composite material was prepared according to an atomic molar ratio of Ag to In of 6.0%, the only difference between the preparation method and example 2 being: step S3 used 0.8mL AgNO₃And 0.8ml of an NaOH solution. Other parameters and the corresponding preparation method of the gas sensor are the same as those in example 2, and are not described again. Ag-modified In of this example₂O₃The composite was recorded as 6.0 at.% Ag/In₂O₃。

Example 4

Ag-modified In of this example₂O₃The composite material was prepared according to an atomic molar ratio of Ag to In of 8.0%, the only difference between the preparation method and example 2 being: step S3 used 1.067mL AgNO₃And 1.067ml of naoh solution. Other parameters and the corresponding preparation method of the gas sensor are the same as those in example 2, and are not described again. Ag-modified In of this example₂O₃Composite material scored 8.0 at.% Ag/In₂O₃。

Example 5

Ag-modified In of this example₂O₃The composite material was prepared In such a manner that the atomic molar ratio of Ag to In was 10.0%, the preparation method thereof was similar to that of example 2The only difference is that: step S3 uses 1.333mLAgNO₃And 1.333ml of NaOH solution. Other parameters and the corresponding preparation method of the gas sensor are the same as those in example 2, and are not described again. Ag-modified In of this example₂O₃The composite was recorded as 10.0 at.% Ag/In₂O₃。

Examples of the experiments

In modified with Ag In the above examples₂O₃Characterization tests were performed on the composite materials and for Ag-modified In the above examples₂O₃The gas sensor was subjected to performance tests, and the results are as follows.

FIG. 1 shows Ag-modified In provided In examples 1 to 5 of the present invention₂O₃X-ray diffraction pattern of composite material In₂O₃And In₂O₃The standard peak (JCPDS: 001-. Ag completely corresponded to the Ag standard peak (JCPDS:87-0579), demonstrating Ag-modified In₂O₃The composite material is successfully prepared and has good crystallinity.

FIG. 2 shows Ag-modified In provided In embodiments 1 to 5 of the present invention₂O₃Response of the gas sensor to 500ppm methane as a function of temperature. As can be seen, after Ag modification, the optimal working temperature of the sensor is reduced from 140 ℃ to 120 ℃, and the sensitivity (i.e. response value) can reach 27.464 at most. Wherein, the sensitivity is the resistance value R of the sensor in the air_aAnd the resistance value R in the gas to be measured_gThe ratio of (a) to (b) is expressed as: r ═ S_a/R_g。

FIG. 3 shows Ag-modified In provided In embodiments 1 to 5 of the present invention₂O₃The gas sensor is used for detecting CH with different concentrations (10-5000 ppm)₄Dynamic response recovery curve of gas. It can be seen from the figure that Ag modified In examples 2-5 was found at all concentrations₂O₃The response of the composite material is higher than that of pure In₂O₃The embodiment can be used in a larger concentration range, and is more suitable for practical application scenes.

FIG. 4 shows Ag-modified In provided In embodiments 1 to 5 of the present invention₂O₃Gas sensor operating at optimum temperature5000ppm of methane, 24ppm of CO, 40ppm of ammonia water, 50ppm of water, 1ppm of formaldehyde, 1ppm of toluene and 1ppm of methanol gas are respectively introduced to investigate Ag modified In₂O₃The gas sensor of (2) is selective for methane. It can be seen from the figure that Ag modified In prepared by the invention₂O₃The composite material has good selectivity to methane.

FIG. 5 shows Ag-modified In provided In embodiments 1 to 5 of the present invention₂O₃Cyclability test of the gas sensor to 300ppm methane. As can be seen from the figure, Ag modifies In₂O₃The gas sensor has good repeatability for detecting methane.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.