Ammonia gas sensor and preparation method thereof

Abstract

The application belongs to the technical field of sensors, and discloses an ammonia gas-sensitive sensor and a preparation method thereof. The ammonia gas-sensitive sensor comprises an insulating substrate and an interdigital electrode, wherein: the interdigital electrode is arranged on the insulating substrate, and the surfaces of the interdigital electrode and the insulating substrate are both coated with a gas-sensitive coating; the raw material for preparing the gas-sensitive coating comprises a gas-sensitive material, and the chemical general formula of the gas-sensitive material is: Ba 1‑x Y x TiO3, wherein 0.002<=x<=0.01. The application introduces specific rare earth ions Y 3+ into the A-site of the BaTiO3 lattice for donor doping, utilizes Y 3+ to replace Ba 2+ , and generates a donor doping effect, which increases the free electron concentration in the conduction band of the material, not only significantly improves the initial conductivity of the material in the air, and provides an excellent signal base for resistance change, but also optimizes the concentration and activity of the surface adsorbed oxygen of the material, and realizes high-sensitivity and selectivity detection of ammonia gas.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of sensors, and particularly relates to an ammonia gas sensitive sensor and a preparation method thereof. BACKGROUND

[0002] Ammonia is an important industrial raw material and a potential zero-carbon energy carrier, and is widely used in the fields of chemical industry, agriculture, food processing and energy. However, ammonia has strong irritancy and toxicity, and its leakage not only seriously endangers the human respiratory system, but also reacts with atmospheric pollutants to generate secondary particulate matter, posing a threat to environmental safety and public health. Therefore, it is of great practical significance to develop a high-performance sensor that can accurately monitor the concentration of ammonia in real time.

[0003] At present, commercial ammonia sensors mainly include electrochemical sensors, optical sensors and semiconductor metal oxide sensors. Among them, the electrochemical sensor has high sensitivity, but generally has the disadvantages of short service life, the need for regular maintenance and being easily affected by environmental temperature and humidity; the optical sensor has high selectivity and precision, but the equipment cost is high, the system is complex, and it is difficult to popularize and apply on a large scale; the semiconductor metal oxide sensor is concerned due to its low cost and simple structure.

[0004] Therefore, there is an urgent need to develop a new type of semiconductor metal oxide gas sensitive sensor to realize high sensitivity and selectivity detection of ammonia. SUMMARY

[0005] The present application aims to at least solve one of the technical problems existing in the prior art. To this end, the present application proposes an ammonia gas sensitive sensor and a preparation method thereof, which can work at room temperature and has high sensitivity and good selectivity for ammonia detection.

[0006] The inventive concept of the present application is that barium titanate (BaTiO3) is a typical perovskite semiconductor metal oxide, which is favored in the field of functional ceramics (such as ferroelectric ceramics) due to its excellent chemical stability and high temperature resistance. At the same time, as a wide-bandgap n-type semiconductor material, its nanostructure can theoretically provide a larger specific surface area for gas adsorption and reaction, and has potential application value in the field of gas sensitive sensors. However, the intrinsic barium titanate usually exhibits intrinsic low conductivity at room temperature, which leads to high substrate resistance when used as a sensing material, making it difficult to produce significant and easily detectable changes in electrical signals. Moreover, the adsorption and reaction activity of the intrinsic barium titanate to ammonia molecules is insufficient, resulting in weak response signal and unsatisfactory sensitivity of the sensor, which cannot meet the needs of actual detection, seriously limiting its practical application in normal temperature ammonia detection. In view of this, the present application introduces specific rare earth ions Y 3+ A-site donor-doped BaTiO3 lattice, utilizes Y3+ Substitute Ba 2+ The generated donor doping effect to increase the free electron concentration in the conduction band of the material, not only can significantly improve its initial conductivity in the air, to provide excellent signal resistance change; and, these additional electrons can also optimize the concentration and activity of the material surface adsorbed oxygen (O2 - , O - , etc.). When the yttrium-doped barium titanate is exposed to ammonia gas, NH3 molecules react with high-activity adsorbed oxygen (4NH3+ 5O2 - → 4NO + 6H2O + 5e - ), the released electrons return to the conduction band, making the surface electron depletion layer thin rapidly, thereby initiating a significant resistance drop at room temperature, and further realizing high-sensitivity selective detection of ammonia gas.

[0007] To solve the above technical problems, the first aspect of the present application provides an ammonia gas sensitive sensor, comprising an insulating substrate and an interdigital electrode, the interdigital electrode is arranged on the insulating substrate, and the surface of the interdigital electrode and the insulating substrate is coated with a gas sensitive coating; the raw material for preparing the gas sensitive coating comprises a gas sensitive material, and the chemical general formula of the gas sensitive material is: Ba 1-x Y x TiO3, wherein 0.002≤x≤0.01.

[0008] Specifically, the ammonia gas sensitive sensor of the present application uses yttrium-doped barium titanate as a gas sensitive material, that is, in the perovskite BaTiO3 system, Y 3+ is doped into the A site to replace Ba 2+ , introducing a positive center. In order to maintain electrical neutrality, the BaTiO3 lattice will produce electron compensation (i.e. conduction band electrons) or oxygen vacancies, thereby effectively solving the core technical problems of BaTiO3 room temperature high resistance and low response. At the same time, the Y-doped BaTiO3 gas sensitive material can exhibit a significantly enhanced resistance response to low-concentration ammonia gas (such as 50 ppm) at room temperature, and in the presence of various interfering gases (such as ethanol, CO, H2), it still exhibits a response signal significantly better than other gases, and has high selectivity for ammonia gas recognition in a complex atmosphere.

[0009] Therefore, the ammonia gas sensitive sensor of the present application can be used to detect different concentrations of ammonia gas in the environment, by monitoring the resistance value change of the gas sensitive material in real time, using the relationship between the resistance value change and the ammonia concentration, qualitative and quantitative detection of ammonia can be realized. At the same time, the gas sensitive sensor can realize high-sensitivity detection of ammonia at room temperature.

[0010] In some embodiments of the present application, the gas sensitive material is prepared by a hydrothermal method, comprising the following steps:

[0011] dissolving a soluble barium salt and a soluble yttrium salt in water to obtain a mixed solution;

[0012] dissolving polyethylene glycol in water and adding acetic acid to obtain solution A;

[0013] dissolving tetrabutyl titanate in ethanol to obtain solution B;

[0014] adding the solution B to the solution A and heating to form Ti(OH)4 precipitate; centrifuging, washing and drying to obtain Ti(OH)4 powder;

[0015] adding the Ti(OH)4 powder to the mixed solution, stirring and performing hydrothermal reaction to form a suspension; centrifuging, washing and drying to obtain the gas-sensitive material.

[0016] Specifically, the application uses a hydrothermal method to prepare a Y-doped BaTiO3 gas-sensitive material in nanoscale, so as to increase the specific surface area thereof, provide more active sites for adsorption and surface reaction of ammonia gas, be beneficial to enhancing the interaction between the gas-sensitive material and ammonia gas molecules, thereby generating a strong resistance signal change, and further improving the sensitivity of the sensor.

[0017] In some embodiments of the application, the soluble barium salt comprises Ba(OH)2·8H2O.

[0018] In some embodiments of the application, the soluble yttrium salt comprises Y(NO3)3·6H2O.

[0019] In some embodiments of the application, in the mixed solution, the concentration of the mixed solution is 0.1-0.2 mol / L, and the amount of the soluble barium salt and the soluble yttrium salt is consistent with the stoichiometric ratio in the chemical formula of the gas-sensitive material. That is, the molar ratio of the soluble barium salt and the soluble yttrium salt is (0.990-0.998):(0.02-0.01).

[0020] In some embodiments of the application, in the solution A, the concentration of polyethylene glycol is 4-6 g / L, and the volume ratio of water to acetic acid is (5-8):1.

[0021] In some embodiments of the application, in the solution B, the concentration of tetrabutyl titanate is 2-3 mol / L.

[0022] In some embodiments of the application, the heating temperature is 70-80℃.

[0023] In some embodiments of the present application, the molar ratio of the Ti(OH)4 powder to the solute in the mixed solution is 1:(1.5-2.5), and the solute in the mixed solution comprises a soluble barium salt and a soluble yttrium salt.

[0024] In some embodiments of the present application, the temperature of the hydrothermal reaction is 150-200℃, and the time of the hydrothermal reaction is 5-20 hours.

[0025] In some embodiments of the present application, the interdigital electrode is a gold electrode.

[0026] In some embodiments of the present application, the electrode spacing of the interdigital electrode is 40-60μm, and the finger width of the interdigital electrode is 80-120μm.

[0027] In some embodiments of the present application, the insulating substrate is an alumina ceramic substrate.

[0028] The second aspect of the present application provides a preparation method of the ammonia gas sensor as described above, comprising the following steps:

[0029] The gas sensitive material is made into a gas sensitive slurry, and then the gas sensitive slurry is coated on the surface of the interdigital electrode and the insulating substrate, and after drying, a gas sensitive coating is formed to obtain the ammonia gas sensor.

[0030] In some embodiments of the present application, the gas sensitive slurry is obtained by mixing the gas sensitive material with anhydrous ethanol.

[0031] The above technical solution of the present application has at least the following technical effects or advantages compared with the prior art:

[0032] (1) The ammonia gas sensor of the present application uses yttrium-doped barium titanate as the gas sensitive material, and by introducing specific rare earth ions Y 3+ The A-site donor doping is performed on the BaTiO3 lattice, and Y 3+ substitutes Ba 2+ The generated donor doping effect increases the free electron concentration in the conduction band of the material, not only significantly improves the initial conductivity in air, but also provides an excellent signal substrate for resistance change; moreover, these extra electrons also optimize the concentration and activity of the adsorbed oxygen on the material surface, and at room temperature, the material can exhibit a significantly enhanced resistance response to low-concentration ammonia gas and exhibit high selectivity, achieving high sensitivity and selective detection of ammonia gas.

[0033] (2) The Y-doped BaTiO3 gas sensitive material in nanometer scale is prepared by the hydrothermal method, so as to increase the specific surface area, provide more active sites for the adsorption and surface reaction of ammonia gas, greatly enhance the interaction between the gas sensitive material and ammonia gas molecules, thereby generating strong resistance signal change, and further improve the sensitivity of the sensor. The hydrothermal synthesis method has mild conditions, good repeatability, is easy to realize large-scale production, and reduces the manufacturing cost. BRIEF DESCRIPTION OF DRAWINGS

[0034] Fig. 1 is the response-recovery curve of the ammonia gas sensitive sensor prepared in Example 1 and Comparative Example 1 under the ammonia gas concentration of 50 ppm;

[0035] Fig. 2 is the gas response value of the ammonia gas sensitive sensor prepared in Examples 1-3 and Comparative Example 1 under the ammonia gas concentration of 50 ppm. DETAILED DESCRIPTION

[0036] The application will be described in detail below with reference to the examples, so as to facilitate the understanding of the application by the person skilled in the art. It is necessary to particularly point out here that the examples are only used to further illustrate the application and cannot be understood as limiting the protection scope of the application. The person skilled in the art can make non-essential improvements and adjustments to the application according to the above application content, which should still belong to the protection scope of the application. Meanwhile, the raw materials mentioned below are not specifically described, which are all commercially available products; the process steps or preparation methods not specifically mentioned are all known process steps or preparation methods to the person skilled in the art.

[0037] Example 1

[0038] An ammonia gas sensitive sensor, comprising an alumina ceramic substrate and an interdigital gold electrode (the electrode spacing is 50 μm, and the finger width is 100 μm), the interdigital gold electrode is arranged on the alumina ceramic substrate, and the surface of the interdigital gold electrode and the alumina ceramic substrate is coated with a gas sensitive coating; the raw materials for preparing the gas sensitive coating comprise a gas sensitive material, and the chemical formula of the gas sensitive material is: Ba 0.998 Y 0.002 TiO3.

[0039] The preparation method of the above ammonia gas sensitive sensor comprises the following steps:

[0040] (1) Ba(OH)2·8H2O powder and Y(NO3)3·6H2O powder are weighed according to the molar ratio of 0.998:0.002, dissolved in water to prepare a mixed solution with a concentration of 0.2 mol / L.

[0041] (2) Polyethylene glycol is dissolved in deionized water at a concentration of 5 g / L, and acetic acid (volume ratio of water to acetic acid is 5:1) is added to prepare solution A; tetrabutyl titanate is dissolved in ethanol to prepare solution B with a concentration of 2 mol / L; then solution B is fully stirred and slowly added to solution A, and constant stirring is carried out at 80°C to generate white Ti(OH)4 precipitate, which is centrifuged, washed and dried to obtain Ti(OH)4 powder.

[0042] (3) The Ti(OH)4 powder prepared in step (2) is slowly added to the mixed solution prepared in step (1), and the molar ratio of Ti(OH)4 powder to the sum of Ba(OH)2·8H2O powder and Y(NO3)3·6H2O powder is 2:1; after uniform stirring, it is transferred to a reaction kettle for hydrothermal reaction at a temperature of 200°C for 5 hours to obtain a suspension, which is then centrifuged, washed and dried to obtain a gas-sensitive material powder.

[0043] (4) The gas-sensitive material powder prepared in step (3) is added to anhydrous ethanol and ultrasonically dispersed to form a gas-sensitive slurry; then the gas-sensitive slurry is coated on the surface of the interdigital gold electrode and the alumina ceramic substrate, and dried to form a gas-sensitive coating layer, thereby obtaining an ammonia gas sensor of the embodiment.

[0044] The ammonia gas sensor prepared in Example 1 is placed in a controllable gas test chamber, and at room temperature, dry and clean air is first introduced as a background gas, and after the resistance of the sensor stabilizes, 50 ppm of ammonia standard gas is introduced, and the resistance change is detected; when the response reaches a constant value, the chamber is removed to allow the gas to diffuse, and the sensor is exposed to air for recovery. The test results are shown in Figs. 1-2 . Figs. 1-2 It can be seen that the response value of the sensor to ammonia at room temperature is 36%, and the response time and recovery time are 14 s and 16 s, respectively, which exhibits excellent room temperature ammonia sensing properties.

[0045] Example 2

[0046] An ammonia gas sensor includes an alumina ceramic substrate and an interdigital gold electrode (electrode spacing is 50 μm, and finger width is 100 μm), the interdigital gold electrode is arranged on the alumina ceramic substrate, and the surfaces of the interdigital gold electrode and the alumina ceramic substrate are both coated with a gas-sensitive coating layer; the raw materials for preparing the gas-sensitive coating layer include a gas-sensitive material, and the chemical formula of the gas-sensitive material is Ba 0.996 Y 0.004 TiO3.

[0047] The preparation method of the above-mentioned ammonia gas sensor includes the following steps:

[0048] (1) Ba(OH)2·8H2O powder and Y(NO3)3·6H2O powder were weighed according to the molar ratio of 0.996:0.004, dissolved in water to prepare a mixed solution with a concentration of 0.1 mol / L.

[0049] (2) Polyethylene glycol was dissolved in deionized water at a concentration of 5 g / L, and acetic acid (volume ratio of water to acetic acid was 8:1) was added to prepare solution A; tetrabutyl titanate was dissolved in ethanol to prepare solution B with a concentration of 3 mol / L; then solution B was fully stirred and slowly added to solution A, and constant stirring was carried out at 80°C to generate white Ti(OH)4 precipitate, which was centrifuged, washed and dried to obtain Ti(OH)4 powder.

[0050] (3) The Ti(OH)4 powder prepared in step (2) was slowly added to the mixed solution prepared in step (1), and the molar ratio of Ti(OH)4 powder to the sum of Ba(OH)2·8H2O powder and Y(NO3)3·6H2O powder was 2:1; after stirring, it was transferred to a reaction kettle for hydrothermal reaction at a temperature of 150°C for 20 hours to obtain a suspension, which was then centrifuged, washed and dried to obtain a gas sensitive material powder.

[0051] (4) The gas sensitive material powder prepared in step (3) was added to anhydrous ethanol and ultrasonically dispersed to form a gas sensitive slurry; then the gas sensitive slurry was coated on the surface of the interdigital gold electrode and the alumina ceramic substrate, and dried to form a gas sensitive coating layer, thereby preparing an ammonia gas sensor of the present embodiment.

[0052] The ammonia gas sensor prepared in Example 2 was placed in a controllable gas test chamber, and dry and clean air was first introduced as a background gas at room temperature. After the resistance of the sensor stabilized, 50 ppm of ammonia standard gas was introduced, and the resistance change was detected. When the response reached a constant value, the chamber was removed to allow the gas to diffuse, and the sensor was exposed to air for recovery. The test results are shown in Fig. 2 Fig. 2 It can be seen from the

[0053] Example 3

[0054] An ammonia gas sensor includes an alumina ceramic substrate and an interdigital gold electrode (electrode spacing is 50 μm, and finger width is 100 μm). The interdigital gold electrode is arranged on the alumina ceramic substrate, and the surface of the interdigital gold electrode and the alumina ceramic substrate is coated with a gas sensitive coating layer. The raw materials for preparing the gas sensitive coating layer include a gas sensitive material, and the chemical formula of the gas sensitive material is Ba 0.99 Y 0.01 TiO3.

[0055] ​The preparation method of the ammonia gas sensor comprises the following steps:

[0056] (1) Ba(OH)2·8H2O powder and Y(NO3)3·6H2O powder are weighed according to a molar ratio of 0.99:0.01, dissolved in water to prepare a mixed solution with a concentration of 0.2 mol / L.

[0057] (2) Polyethylene glycol is dissolved in deionized water at a concentration of 5 g / L, and acetic acid (volume ratio of water to acetic acid is 5:1) is added to prepare solution A; tetrabutyl titanate is dissolved in ethanol to prepare solution B with a concentration of 2 mol / L; then solution B is fully stirred and slowly added to solution A, and constant stirring is carried out at 80°C to generate white Ti(OH)4 precipitate, which is centrifuged, washed and dried to obtain Ti(OH)4 powder.

[0058] (3) The Ti(OH)4 powder prepared in step (2) is slowly added to the mixed solution prepared in step (1), and the molar ratio of the Ti(OH)4 powder to the sum of the Ba(OH)2·8H2O powder and the Y(NO3)3·6H2O powder is 2:1; after uniform stirring, the mixture is transferred to a reaction kettle for hydrothermal reaction at a temperature of 200°C for 10 hours to obtain a suspension, which is then centrifuged, washed and dried to obtain a gas-sensitive material powder.

[0059] (4) The gas-sensitive material powder prepared in step (3) is added to anhydrous ethanol and ultrasonically dispersed to form a gas-sensitive slurry; then the gas-sensitive slurry is coated on the surface of the interdigital gold electrode and the alumina ceramic substrate, and dried to form a gas-sensitive coating layer, thereby obtaining the ammonia gas sensor of the embodiment.

[0060] The ammonia gas sensor prepared in Example 3 is placed in a controllable gas test chamber, dry and clean air is first introduced as a background gas at room temperature, and when the resistance of the sensor stabilizes, 50 ppm of ammonia standard gas is introduced, and the resistance change is detected; when the response reaches a constant value, the chamber is removed to allow the gas to diffuse, and the sensor is exposed to air for recovery. The test results are shown in Fig. 2 As shown in Fig. 2 , the response value of the sensor to ammonia at room temperature is 32%, which exhibits excellent room temperature ammonia sensing properties.

[0061] Comparative Example 1

[0062] An ammonia gas sensor comprises an alumina ceramic substrate and an interdigital gold electrode (electrode spacing is 50 μm, finger width is 100 μm), the interdigital gold electrode is arranged on the alumina ceramic substrate, and the surface of the interdigital gold electrode and the alumina ceramic substrate is coated with a gas-sensitive coating layer; the raw materials for preparing the gas-sensitive coating layer include a gas-sensitive material, and the chemical formula of the gas-sensitive material is BaTiO3.

[0063] The preparation method of the above-mentioned ammonia gas sensor includes the following steps:

[0064] (1) Weigh out Ba(OH)2·8H2O powder and dissolve it in water to prepare a solution with a concentration of 0.2mol / L.

[0065] (2) Polyethylene glycol was dissolved in deionized water at a concentration of 5 g / L, and then acetic acid was added (the volume ratio of water to acetic acid was 5:1) to prepare solution A; tetrabutyl titanate was dissolved in ethanol to prepare solution B with a concentration of 2 mol / L; then solution B was stirred thoroughly and slowly added to solution A, and stirred continuously at a constant temperature of 80℃ to generate white Ti(OH)4 precipitate. After centrifugation, washing and drying, Ti(OH)4 powder was obtained.

[0066] (3) The Ti(OH)4 powder obtained in step (2) is slowly added to the solution obtained in step (1), wherein the molar ratio of Ti(OH)4 powder to Ba(OH)2·8H2O powder is 2:1. After stirring evenly, the solution is transferred to a reaction vessel for hydrothermal reaction. The reaction is carried out at 200℃ for 5 hours to obtain a suspension. After centrifugation, washing and drying, the gas-sensitive material powder is obtained.

[0067] (4) The gas-sensitive material powder obtained in step (3) is added to anhydrous ethanol and dispersed by ultrasonication to form a gas-sensitive slurry; then the gas-sensitive slurry is coated on the surface of the interdigitated gold electrode and the alumina ceramic substrate, and after drying, a gas-sensitive coating is formed to obtain the ammonia gas-sensitive sensor of this comparative example.

[0068] The ammonia gas sensor prepared in Comparative Example 1 was placed in a controllable gas testing chamber. At room temperature, dry, clean air was first introduced as a background gas. After the sensor resistance stabilized, 50 ppm of ammonia standard gas was introduced, and the resistance change was measured. When the response reached a constant value, the chamber was removed to allow gas diffusion, and the sensor was exposed to air for recovery. The test results are as follows: Figs. 1-2 As shown. By Figs. 1-2 It can be seen that the response value of this sensor to ammonia at room temperature is 18%, and the response time and recovery time are 16s and 18s, respectively. Its sensitivity is far less than that of the ammonia gas sensor prepared in Example 1.

[0069] Comparing the detection results of the ammonia gas sensors prepared in Example 1 and Comparative Example 1, it can be seen that under exactly the same preparation and testing conditions, the response signal of undoped pure phase BaTiO3 to ammonia at room temperature is extremely weak, and it has almost no effective detection capability; while the response signal of the Y-phase gas sensor prepared in Example 1 is extremely weak, and it has almost no effective detection capability. 3+ After doping, the resulting material exhibits a strong resistive response to the same concentration of ammonia gas, with a significant increase in the response value. This proves that Y... 3+Doping plays a decisive role in "activating" the BaTiO3 room temperature ammonia sensitive characteristics, successfully transforming a nearly ineffective material in room temperature ammonia detection into a high-performance sensitive material.

[0070] For those skilled in the art to which this application belongs, several simple deductions or substitutions can be made without departing from the concept of the present application, without having to undergo creative labor. Therefore, simple improvements made by those skilled in the art to the present application, based on the disclosure of the present application, should be within the scope of protection of the present application. The above examples are preferred embodiments of the present application, and any similar processes and equivalent changes made thereto should be within the scope of protection of the present application.

Claims

1. An ammonia gas sensor, characterized by comprising: The application relates to a gas sensor, which comprises an insulating substrate and interdigital electrodes arranged on the insulating substrate, and surfaces of the interdigital electrodes and the insulating substrate are coated with a gas-sensitive coating; raw materials for preparing the gas-sensitive coating comprise a gas-sensitive material, and the gas-sensitive material has a general chemical formula of Ba 1-x Y x TiO3, wherein 0.002<=x<=0.

01. The gas-sensitive material is prepared by a hydrothermal method, and comprises the following steps: dissolving soluble barium salt and soluble yttrium salt in water to obtain a mixed solution; dissolving polyethylene glycol in water and adding acetic acid to obtain solution A; in the solution A, the concentration of polyethylene glycol is 4-6 g / L, and the volume ratio of water to acetic acid is (5-8):1; dissolving tetrabutyl titanate in ethanol to obtain solution B; adding the solution B into the solution A, heating to 70-80℃ to generate Ti(OH)4 precipitate; centrifuging, washing and drying to obtain Ti(OH)4 powder; the molar ratio of the Ti(OH)4 powder to the solute in the mixed solution is 1:(1.5-2.5); adding the Ti(OH)4 powder into the mixed solution, stirring, and performing hydrothermal reaction at 150-200℃ for 5-20 hours to form a suspension; centrifuging, washing and drying to obtain the gas-sensitive material.

2. The ammonia gas sensor according to claim 1, wherein The soluble barium salt comprises Ba(OH)2·8H2O, and the soluble yttrium salt comprises Y(NO3)3·6H2O; the concentration of the mixed solution is 0.1-0.2 mol / L, and the amount ratio of the soluble barium salt and the soluble yttrium salt is consistent with the stoichiometric ratio in the chemical formula of the gas-sensitive material.

3. The ammonia gas sensor according to claim 1, wherein In the solution B, the concentration of tetrabutyl titanate is 2-3 mol / L.

4. The ammonia gas sensor according to claim 1, wherein The interdigital electrode is a gold electrode, and the insulating substrate is an alumina ceramic substrate.

5. A method for producing an ammonia gas sensor as claimed in any one of claims 1 to 4, characterized by, comprising the following steps: The gas-sensitive material is prepared into a gas-sensitive slurry, then the gas-sensitive slurry is coated on the surface of the interdigital electrode and the insulating substrate, dried to form a gas-sensitive coating, and the ammonia gas-sensitive sensor is prepared.

Images