Ammonia gas sensor and preparation method thereof

Abstract

The invention 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, the interdigital electrode is arranged on the insulating substrate, and the surfaces of the interdigital electrode and the insulating substrate are coated with gas sensitive coatings; raw materials for preparing the gas-sensitive coating comprise a gas-sensitive material, the general chemical formula of the gas-sensitive material is Ba (1-x) YxTiO3, and x is more than or equal to 0.002 and less than or equal to 0.01. Specific rare earth ions Y < 3 + > are introduced to carry out A-site donor doping on BaTiO3 crystal lattices, the donor doping effect generated by replacing Ba < 2 + > with Y < 3 + > is utilized, the free electron concentration in a material conduction band is increased, the initial conductivity of the material in air is remarkably improved, and an excellent signal substrate is provided for resistance change; in addition, the additional electrons also optimize the concentration and activity of oxygen adsorbed on the surface of the material, and high-sensitivity and selective detection of ammonia gas is realized.

Description

Technical Field

[0001] This invention belongs to the field of sensor technology, specifically relating to an ammonia gas sensor and its preparation method. Background Technology

[0002] Ammonia, as an important industrial raw material and a potential zero-carbon energy carrier, is widely used in the chemical, agricultural, food processing, and energy sectors. However, ammonia is also highly irritating and toxic; its leakage can seriously harm the human respiratory system and react with atmospheric pollutants to generate secondary particulate matter, posing a threat to environmental safety and public health. Therefore, developing high-performance sensors capable of real-time and accurate monitoring of ammonia concentration is of great practical significance.

[0003] Currently, commercially available ammonia sensors mainly include electrochemical sensors, optical sensors, and semiconductor metal oxide sensors. Among them, electrochemical sensors have high sensitivity, but generally suffer from short lifespan, require regular maintenance, and are susceptible to the effects of ambient temperature and humidity; optical sensors have high selectivity and accuracy, but the equipment is expensive and the system is complex, making it difficult to widely apply; semiconductor metal oxide sensors have attracted much attention due to their low cost and simple structure. Therefore, there is an urgent need to develop a new type of semiconductor metal oxide gas sensor to achieve highly sensitive and selective detection of ammonia. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes an ammonia gas sensor and its preparation method. The gas sensor can operate at room temperature and has high sensitivity and good selectivity for ammonia detection.

[0005] The inventive concept of this invention is as follows: Barium titanate (BaTiO3), as a typical perovskite-type semiconductor metal oxide, is highly favored in the field of functional ceramics (such as ferroelectric ceramics) due to its excellent chemical stability and high-temperature resistance. Simultaneously, as a wide-bandgap n-type semiconductor material, its nanostructure theoretically provides a large specific surface area for gas adsorption and reaction, showing potential application value in the field of gas sensing. However, intrinsic barium titanate typically exhibits intrinsically low conductivity at room temperature, resulting in excessively high matrix resistance when used as a sensing material, making it difficult to generate significant and easily detectable electrical signal changes. Moreover, intrinsic barium titanate has insufficient adsorption and reaction activity for ammonia molecules, leading to weak sensor response signals and unsatisfactory sensitivity, failing to meet the needs of practical detection, which severely limits its practical application in room-temperature ammonia detection. To address this, this invention introduces a specific rare earth ion, Y... 3+ A-site donor doping of BaTiO3 lattice was performed using Y 3+ Replace Ba2+ The resulting donor doping effect, which increases the concentration of free electrons in the material's conduction band, not only significantly improves its initial conductivity in air, providing an excellent signal substrate for resistance changes, but also optimizes oxygen (O2) adsorption on the material surface. - O - The concentration and activity of yttrium-doped barium titanate (YT) are also considered. When YT is exposed to ammonia, NH3 molecules react with highly active adsorbed oxygen (4NH3 + 5O2). - → 4NO + 6H2O + 5e - The released electrons return to the conduction band, causing the surface electron depletion layer to thin rapidly, which in turn induces a significant decrease in resistance at room temperature, thereby enabling highly sensitive and selective detection of ammonia.

[0006] To address the aforementioned technical problems, a first aspect of the present invention provides an ammonia gas sensor, comprising an insulating substrate and interdigitated electrodes, wherein the interdigitated electrodes are disposed on the insulating substrate, and both the surfaces of the interdigitated electrodes and the insulating substrate are coated with a gas-sensitive coating; the raw materials for preparing the gas-sensitive coating include a gas-sensitive material, the general chemical formula of which is Ba. 1-x Y x TiO3, where 0.002≤x≤0.01.

[0007] Specifically, the ammonia gas sensor of the present invention uses yttrium-doped barium titanate as the gas-sensitive material, that is, in the perovskite BaTiO3 system, Y... 3+ Doping to replace Ba at the A site 2+ By introducing positively charged centers, the BaTiO3 lattice generates electron compensation (i.e., conduction band electrons) or oxygen vacancies to maintain electroneutrality, effectively solving the core technical problem of high resistance and low response of BaTiO3 at room temperature. Simultaneously, Y-doped BaTiO3 gas-sensitive materials exhibit significantly enhanced resistance response to low concentrations of ammonia (e.g., 50 ppm) at room temperature. Even under conditions where multiple interfering gases (e.g., ethanol, CO, H2) coexist, they still show a significantly better response signal to ammonia than other gases, demonstrating high selectivity for ammonia recognition in complex atmospheres.

[0008] Therefore, the ammonia gas sensor of the present invention can be used to detect ammonia gas of different concentrations in the environment. By monitoring the change in resistance value of the gas-sensitive material in real time, and utilizing the relationship between the change in resistance value and the ammonia concentration, qualitative and quantitative detection of ammonia can be achieved. Furthermore, this gas sensor can achieve high-sensitivity detection of ammonia gas at room temperature.

[0009] In some embodiments of the present invention, the gas-sensitive material is prepared by a hydrothermal method, including the following steps: A mixed solution is prepared by dissolving soluble barium salt and soluble yttrium salt in water; Polyethylene glycol is dissolved in water, and acetic acid is added to prepare solution A; Tetrabutyl titanate was dissolved in ethanol to prepare solution B; Solution B was added to solution A and heated to generate Ti(OH)4 precipitate; after centrifugation, washing and drying, Ti(OH)4 powder was obtained. The Ti(OH)4 powder was added to the mixed solution, stirred, and subjected to a hydrothermal reaction to form a suspension; after centrifugation, washing, and drying, the gas-sensitive material was obtained.

[0010] Specifically, this invention uses a hydrothermal method to prepare nanoscale Y-doped BaTiO3 gas-sensitive materials to increase their specific surface area, providing more active sites for ammonia adsorption and surface reactions. This enhances the interaction between the gas-sensitive material and ammonia molecules, thereby generating strong resistance signal changes and further improving the sensitivity of the sensor.

[0011] In some embodiments of the present invention, the soluble barium salt includes Ba(OH)2·8H2O.

[0012] In some embodiments of the present invention, the soluble yttrium salt includes Y(NO3)3·6H2O.

[0013] In some embodiments of the present invention, the concentration of the mixed solution is 0.1-0.2 mol / L, and the ratio of the amounts of the soluble barium salt and the soluble yttrium salt is consistent with the stoichiometric ratio in the general chemical formula of the gas-sensitive material. That is, the molar ratio of the soluble barium salt to the soluble yttrium salt is (0.990-0.998):(0.02-0.01).

[0014] In some embodiments of the present invention, in 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.

[0015] In some embodiments of the present invention, the concentration of tetrabutyl titanate in solution B is 2-3 mol / L.

[0016] In some embodiments of the present invention, the heating temperature is 70-80°C.

[0017] In some embodiments of the present invention, the molar ratio of the Ti(OH)4 powder to the solute in the mixed solution is 1:(1.5-2.5); the solute in the mixed solution includes soluble barium salt and soluble yttrium salt.

[0018] In some embodiments of the present invention, the temperature of the hydrothermal reaction is 150-200°C, and the time of the hydrothermal reaction is 5-20 hours.

[0019] In some embodiments of the present invention, the interdigitated electrodes are gold electrodes.

[0020] In some embodiments of the present invention, the electrode spacing of the interdigital electrodes is 40-60 μm, and the finger width of the interdigital electrodes is 80-120 μm.

[0021] In some embodiments of the present invention, the insulating substrate is an alumina ceramic substrate.

[0022] A second aspect of the present invention provides a method for preparing the above-mentioned ammonia gas sensor, comprising the following steps: The gas-sensitive material is made into a gas-sensitive slurry, and then the gas-sensitive slurry is coated on the surface of the interdigitated electrode and the insulating substrate. After drying, a gas-sensitive coating is formed to obtain the ammonia gas-sensitive sensor.

[0023] In some embodiments of the present invention, the gas-sensitive slurry is prepared by mixing a gas-sensitive material with anhydrous ethanol.

[0024] Compared with the prior art, the above-described technical solution of the present invention has at least the following technical effects or advantages: (1) The ammonia gas sensor of the present invention uses barium titanate doped with yttrium as the gas-sensitive material, and introduces specific rare earth ions Y. 3+ A-site donor doping of BaTiO3 lattice was performed using Y 3+ Replace Ba 2+ The resulting donor doping effect increases the concentration of free electrons in the material's conduction band, which not only significantly improves its initial conductivity in air, providing an excellent signal substrate for resistance changes, but also optimizes the concentration and activity of oxygen adsorbed on the material surface. This results in a significantly enhanced resistance response to low concentrations of ammonia at room temperature, exhibiting high selectivity and enabling highly sensitive and selective detection of ammonia.

[0025] (2) This invention uses a hydrothermal method to prepare nanoscale Y-doped BaTiO3 gas-sensitive materials to increase their specific surface area, providing more active sites for ammonia adsorption and surface reaction, which greatly enhances the interaction between the gas-sensitive material and ammonia molecules, thereby generating a strong change in resistance signal and further improving the sensitivity of the sensor. Moreover, the hydrothermal synthesis method has mild conditions, good repeatability, and is easy to scale up for production, reducing manufacturing costs. Attached Figure Description

[0026] Figure 1These are the response-recovery curves of the ammonia gas sensors prepared in Example 1 and Comparative Example 1 at an ammonia concentration of 50 ppm; Figure 2 These are the gas response values ​​of the ammonia gas sensors prepared in Examples 1-3 and Comparative Example 1 at an ammonia concentration of 50 ppm. Detailed Implementation

[0027] The present invention will now be described in detail with reference to embodiments to facilitate understanding of the invention by those skilled in the art. It is particularly important to note that the embodiments are merely illustrative of the invention and should not be construed as limiting the scope of protection of the invention. Non-essential improvements and adjustments made to the invention by those skilled in the art based on the above description should still fall within the scope of protection of the invention. Furthermore, all raw materials mentioned below, unless otherwise specified, are commercially available products; all process steps or preparation methods not mentioned in detail are process steps or preparation methods known to those skilled in the art.

[0028] Example 1 An ammonia gas sensor includes an alumina ceramic substrate and interdigitated gold electrodes (electrode spacing of 50 μm and finger width of 100 μm). The interdigitated gold electrodes are disposed on the alumina ceramic substrate, and both the surfaces of the interdigitated gold electrodes and the alumina ceramic substrate are coated with a gas-sensitive coating. The raw materials for preparing the gas-sensitive coating include a gas-sensitive material with the chemical formula Ba. 0.998 Y 0.002 TiO3.

[0029] The preparation method of the above-mentioned ammonia gas sensor includes the following steps: (1) Weigh Ba(OH)2·8H2O powder and Y(NO3)3·6H2O powder in a molar ratio of 0.998:0.002, dissolve them in water, and prepare a mixed solution with a concentration of 0.2mol / L.

[0030] (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.

[0031] (3) The Ti(OH)4 powder obtained in step (2) is slowly added to the mixed solution obtained in step (1), wherein the molar ratio of Ti(OH)4 powder to Ba(OH)2·8H2O powder and Y(NO3)3·6H2O powder is 2:1. After stirring evenly, the mixture 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.

[0032] (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 embodiment.

[0033] The ammonia gas sensor prepared in 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 detected. 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: Figure 1-2 As shown. By Figure 1-2 It can be seen that the sensor has a response value of 36% to ammonia at room temperature, and a response time and recovery time of 14s and 16s, respectively, showing excellent room temperature ammonia sensitivity characteristics.

[0034] Example 2 An ammonia gas sensor includes an alumina ceramic substrate and interdigitated gold electrodes (electrode spacing of 50 μm and finger width of 100 μm). The interdigitated gold electrodes are disposed on the alumina ceramic substrate, and both the surfaces of the interdigitated gold electrodes and the alumina ceramic substrate are coated with a gas-sensitive coating. The raw materials for preparing the gas-sensitive coating include a gas-sensitive material with the chemical formula Ba. 0.996 Y 0.004 TiO3.

[0035] The preparation method of the above-mentioned ammonia gas sensor includes the following steps: (1) Weigh Ba(OH)2·8H2O powder and Y(NO3)3·6H2O powder in a molar ratio of 0.996:0.004, dissolve them in water, and prepare a mixed solution with a concentration of 0.1mol / L.

[0036] (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 8:1) 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 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.

[0037] (3) The Ti(OH)4 powder obtained in step (2) is slowly added to the mixed solution obtained in step (1), wherein the molar ratio of Ti(OH)4 powder to Ba(OH)2·8H2O powder and Y(NO3)3·6H2O powder is 2:1. After stirring evenly, the mixture is transferred to a reaction vessel for hydrothermal reaction. The reaction is carried out at 150°C for 20 hours to obtain a suspension. After centrifugation, washing and drying, the gas-sensitive material powder is obtained.

[0038] (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 embodiment.

[0039] The ammonia gas sensor prepared in Example 2 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 detected. 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: Figure 2 As shown. By Figure 2 It can be seen that the sensor has a response value of 28% to ammonia at room temperature, exhibiting excellent room temperature ammonia sensitivity characteristics.

[0040] Example 3 An ammonia gas sensor includes an alumina ceramic substrate and interdigitated gold electrodes (electrode spacing of 50 μm and finger width of 100 μm). The interdigitated gold electrodes are disposed on the alumina ceramic substrate, and both the surfaces of the interdigitated gold electrodes and the alumina ceramic substrate are coated with a gas-sensitive coating. The raw materials for preparing the gas-sensitive coating include a gas-sensitive material with the chemical formula Ba. 0.99 Y 0.01 TiO3.

[0041] The preparation method of the above-mentioned ammonia gas sensor includes the following steps: (1) Weigh Ba(OH)2·8H2O powder and Y(NO3)3·6H2O powder in a molar ratio of 0.99:0.01, dissolve them in water, and prepare a mixed solution with a concentration of 0.2mol / L.

[0042] (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.

[0043] (3) The Ti(OH)4 powder obtained in step (2) is slowly added to the mixed solution obtained in step (1), wherein the molar ratio of Ti(OH)4 powder to Ba(OH)2·8H2O powder and Y(NO3)3·6H2O powder is 2:1. After stirring evenly, the mixture is transferred to a reaction vessel for hydrothermal reaction. The reaction is carried out at 200℃ for 10 hours to obtain a suspension. After centrifugation, washing and drying, the gas-sensitive material powder is obtained.

[0044] (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 embodiment.

[0045] The ammonia gas sensor prepared in Example 3 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 detected. 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: Figure 2 As shown. By Figure 2 It can be seen that the sensor has a response value of 32% to ammonia at room temperature, exhibiting excellent room temperature ammonia sensitivity characteristics.

[0046] Comparative Example 1 An ammonia gas sensor includes an alumina ceramic substrate and interdigitated gold electrodes (electrode spacing of 50 μm and finger width of 100 μm). The interdigitated gold electrodes are disposed on the alumina ceramic substrate, and both the surface of the interdigitated gold electrodes and the alumina ceramic substrate are coated with a gas-sensitive coating. The raw materials for preparing the gas-sensitive coating include a gas-sensitive material with the chemical formula BaTiO3.

[0047] The preparation method of the above-mentioned ammonia gas sensor includes the following steps: (1) Weigh out Ba(OH)2·8H2O powder and dissolve it in water to prepare a solution with a concentration of 0.2mol / L.

[0048] (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.

[0049] (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.

[0050] (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.

[0051] 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: Figure 1-2 As shown. By Figure 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.

[0052] 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 played a decisive role in "activating" the room-temperature ammonia-sensitive properties of BaTiO3, successfully transforming a material that was almost ineffective in room-temperature ammonia detection into a high-performance sensitive material.

[0053] For those skilled in the art, several simple deductions or substitutions can be made without departing from the inventive concept, without requiring creative effort. Therefore, any simple improvements made to this invention by those skilled in the art based on the disclosure of this invention should be within the scope of protection of this invention. The above embodiments are preferred embodiments of this invention, and all processes similar to this invention and equivalent changes should fall within the scope of protection of this invention.

Claims

1. An ammonia gas sensor, characterized in that, The device includes an insulating substrate and interdigitated electrodes, wherein the interdigitated electrodes are disposed on the insulating substrate, and both the surfaces of the interdigitated electrodes and the insulating substrate are coated with a gas-sensitive coating; the raw materials for preparing the gas-sensitive coating include a gas-sensitive material, the general chemical formula of which is Ba. 1-x Y x TiO3, where 0.002≤x≤0.

01.

2. The ammonia gas sensor according to claim 1, characterized in that, The gas-sensitive material is prepared by a hydrothermal method, including the following steps: A mixed solution is prepared by dissolving soluble barium salt and soluble yttrium salt in water; Polyethylene glycol is dissolved in water, and acetic acid is added to prepare solution A; Tetrabutyl titanate was dissolved in ethanol to prepare solution B; Solution B was added to solution A and heated to generate Ti(OH)4 precipitate; after centrifugation, washing and drying, Ti(OH)4 powder was obtained. The Ti(OH)4 powder was added to the mixed solution, stirred, and subjected to a hydrothermal reaction to form a suspension; after centrifugation, washing, and drying, the gas-sensitive material was obtained.

3. The ammonia gas sensor according to claim 2, characterized in that, The soluble barium salt includes Ba(OH)2·8H2O, and the soluble yttrium salt includes Y(NO3)3·6H2O; 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 general chemical formula of the gas-sensitive material.

4. The ammonia gas sensor according to claim 2, characterized in that, In 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.

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

6. The ammonia gas sensor according to claim 2, characterized in that, The heating temperature is 70-80℃.

7. The ammonia gas sensor according to claim 2, characterized in that, The molar ratio of the Ti(OH)4 powder to the solute in the mixed solution is 1:(1.5-2.5).

8. The ammonia gas sensor according to claim 2, characterized in that, The hydrothermal reaction temperature is 150-200℃, and the hydrothermal reaction time is 5-20 hours.

9. The ammonia gas sensor according to claim 1, characterized in that, The interdigitated electrodes are gold electrodes, and the insulating substrate is an alumina ceramic substrate.

10. A method for preparing an ammonia gas sensor as described in any one of claims 1-9, characterized in that, Includes the following steps: The gas-sensitive material is made into a gas-sensitive slurry, and then the gas-sensitive slurry is coated on the surface of the interdigitated electrode and the insulating substrate. After drying, a gas-sensitive coating is formed to obtain the ammonia gas-sensitive sensor.

Images