Gas sensitive material and preparation method thereof, solid electrolyte gas sensor and refrigerator

Abstract

The invention belongs to the technical field of sensors, and discloses a gas sensitive material and a preparation method thereof, a solid electrolyte gas sensor and a refrigerator. The gas sensitive material comprises AxBy (TiO3) n, x: y = (1-100): (1-100), n is greater than or equal to 1 and less than or equal to 400, and A and B respectively comprise any one of Fe, Co, Ni, Cu, Zn, Mn and Cd. By adopting the gas sensitive material provided by the invention, the sensitivity, selectivity and service life of the solid electrolyte gas sensor can be improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of sensors, and in particular relates to a gas-sensitive material, a preparation method thereof, a solid electrolyte gas sensor and a refrigerator. BACKGROUND

[0002] At present, various food materials are put into a refrigerator, and different food materials diffuse different odors during storage. Different odors mixed together form unpleasant odors. In addition, with the extension of the storage time of aquatic products, protein autolysis and decomposition will occur quickly, and aldehyde gas will be produced due to the growth and metabolism of some microorganisms. Since the refrigerator is a closed space, the odor cannot be discharged, resulting in the existence of odor in the refrigerator. Moreover, aldehyde gas can cause irritation to the skin, mucous membrane and respiratory tract of the human body, and can increase the risk of cancer. Therefore, the detection and prevention of aldehyde gas have become a problem that people are concerned about and need to be solved urgently.

[0003] However, the existing aldehyde gas detection method has the disadvantages of poor selectivity, poor stability and poor sensitivity. SUMMARY

[0004] The present application aims to at least solve one of the technical problems in the related art. To this end, one object of the present application is to provide a gas-sensitive material, a preparation method thereof, a solid electrolyte gas sensor and a refrigerator. The gas-sensitive material provided by the present application can improve the sensitivity, selectivity and service life of the solid electrolyte gas sensor.

[0005] In a first aspect of the present application, a gas-sensitive material is provided. According to an embodiment of the present application, the gas-sensitive material comprises A x B y (TiO3) n , wherein x:y=(1-100):(1-100), 1n400, and A and B each comprises any one of Fe, Co, Ni, Cu, Zn, Mn and Cd.

[0006] According to the gas-sensitive material of the above-mentioned embodiment of the present application, the chemical structural formula of the gas-sensitive material is A x B y (TiO3) n , and A and B each comprises any one of transition metal elements such as Fe, Co, Ni, Cu, Zn, Mn and Cd. Taking Ni and Co as an example, the d orbital of Ni usually has 8 electrons. When it exists in the form of Ni 2+ , it loses two electrons, resulting in a change in the electron distribution in the d orbital, inducing electronic conductivity. By doping low-valence Ni 2+The oxygen defect sites can cause high-concentration electron conduction, which can compensate for the hole accumulation layer in the gas-sensitive material, thereby increasing the rate at which the gas-sensitive material adsorbs aldehyde gas to accept electrons, and thus improving the selectivity of the sensor to aldehyde gas. When cobalt exists in the form of Co 4+ When cobalt exists in the form of Co

[0007] In addition, the gas-sensitive material according to the above embodiments of the present application can also have the following additional technical features:

[0008] In some embodiments of the present application, x:y=(1-10):(1-10). Thereby, the internal electron conduction structure of the gas-sensitive material is adjusted, the binding efficiency of the sensitive electrode surface to aldehyde gas is adjusted, and the reaction rate of aldehyde gas on the electrode surface is adjusted, which is conducive to improving the sensitivity, selectivity and service life of the solid-state electrolyte gas sensor.

[0009] In some embodiments of the present application, x satisfies: 0

[0010] In some embodiments of the present application, the porosity of the gas-sensitive material is 5%-70%. Thereby, the contact opportunity of the gas with the active sites of the gas-sensitive material can be increased, the response speed is accelerated, and the detection lower limit is reduced, which is conducive to improving the sensitivity of the solid-state electrolyte gas sensor.

[0011] In a second aspect, the present application provides a method for preparing the gas sensitive material, according to an embodiment of the present application, the method comprises: preparing a metal titanate wet gel; drying the metal titanate wet gel to obtain a dry gel; and calcining the dry gel under vacuum to obtain the gas sensitive material. Thus, the gas sensitive material with loose porous structure can be obtained, which is beneficial to improve the sensitivity, selectivity and service life of the solid electrolyte gas sensor.

[0012] In some embodiments of the present application, the drying temperature is 25-90℃. Thus, the high specific surface area of the gas sensitive material can be maintained, which is beneficial to improve the sensitivity, selectivity and service life of the solid electrolyte gas sensor.

[0013] In some embodiments of the present application, the mass fraction of water is not more than 45% based on the total mass of the dry gel. Thus, the gas adsorption capacity and sensing performance of the gas sensitive material can be improved, which is beneficial to improve the sensitivity of the solid electrolyte sensor.

[0014] In some embodiments of the present application, the calcining temperature is 400-1200℃. Thus, the pore structure of the gas sensitive material can be optimized, which is beneficial to obtain the gas sensitive material with loose porous structure, and thus the sensitivity of the solid electrolyte gas sensor can be improved.

[0015] In some embodiments of the present application, the calcining time is 0.5-12h. Thus, the pore structure of the gas sensitive material can be further optimized, which is beneficial to obtain the gas sensitive material with loose porous structure, and thus the sensitivity of the solid electrolyte gas sensor can be improved.

[0016] In a third aspect, the present application provides a solid electrolyte gas sensor, according to an embodiment of the present application, the solid electrolyte gas sensor comprises the gas sensitive material described above or the gas sensitive material prepared by the method described above. Thus, the solid electrolyte gas sensor has higher sensitivity and longer service life, and the solid electrolyte gas sensor has better selectivity to aldehyde gas.

[0017] In a fourth aspect, the present application provides a refrigerator, according to an embodiment of the present application, the refrigerator comprises the solid electrolyte gas sensor of the third aspect. Thus, the solid electrolyte gas sensor is used for detecting odor gas in the refrigerator, which can feedback the overall situation of the gas in the refrigerator, so as to serve as the basis for judging the state of the food in the refrigerator.

[0018] Additional aspects and advantages of the present application will be in part apparent and in part pointed out hereinafter. BRIEF DESCRIPTION OF DRAWINGS

[0019] The above and / or additional aspects and advantages of the present application will become apparent and more readily appreciated from the following description, taken in conjunction with the following drawings of exemplary embodiments and wherein:

[0020] Figure 1 A structural diagram of a solid electrolyte gas sensor of an embodiment is shown;

[0021] Figure 2 An SEM image of a gas sensitive material of Example 1 is shown;

[0022] Figure 3 An EDS element distribution map of the gas sensitive material of Example 1 is shown;

[0023] Figure 4 A response curve of a solid electrolyte gas sensor of Example 1 to various aldehyde gases is shown;

[0024] Figure 5 A response fitting curve of a solid electrolyte gas sensor of Example 1 to formaldehyde is shown;

[0025] Figure 6 A response selectivity curve of a solid electrolyte gas sensor of Example 1 to formaldehyde is shown;

[0026] Figure 7 A 100-time response test of a solid electrolyte gas sensor of Example 1 to 10 ppm of formaldehyde is shown.

[0027] List of reference numerals:

[0028] A solid electrolyte gas sensor 100, an insulating base layer 10, a heating electrode layer 20, a solid electrolyte layer 30, a sensitive electrode 40, and a reference electrode 50. DETAILED DESCRIPTION

[0029] Embodiments of the present application are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below are exemplary and are intended to explain the present application, and cannot be understood as limiting the present application.

[0030] In a first aspect of the present application, the present application proposes a gas sensitive material, according to an embodiment of the present application, the gas sensitive material comprises A x B y (TiO3) n wherein x:y=(1-100):(1-100), 1≤n≤400, A and B each comprises any one of Fe, Co, Ni, Cu, Zn, Mn and Cd.

[0031] The gas-sensitive material according to the above embodiment of the present application has a chemical formula of A x B y (TiO3) n , and A and B each include any one of transition metal elements such as Fe, Co, Ni, Cu, Zn, Mn and Cd, the d orbit of the transition metal element can provide a vacancy, form a coordination bond with the oxygen atom in the aldehyde gas, and enhance the combination of the gas molecule and the surface of the gas-sensitive material, thereby improving the selectivity of the sensor to the aldehyde gas. Taking Ni and Co as examples, the d orbit of Ni usually has 8 electrons, and when it exists in the form of Ni 2+ , it loses two electrons, resulting in a change in the electron distribution in the d orbit, inducing electronic conductivity. By doping low-valence Ni 2+ in the gas-sensitive material, oxygen defect sites can be generated to cause high-concentration electronic conduction, which can compensate for the hole accumulation layer in the gas-sensitive material, thereby increasing the rate of adsorption of the aldehyde gas by the gas-sensitive material and accepting electrons, and thus improving the selectivity of the sensor to the aldehyde gas. When Co exists in the form of Co 4+ , it has a low oxygen ion migration activation energy, so that the energy required for the migration of oxygen ions at this position is low, thereby promoting the migration of oxygen ions, which is helpful to improve the adsorption and desorption process of oxygen, and thus is conducive to improving the sensitivity of the sensor. Moreover, the transition metal titanate formed by the combination of A and B with transition metal elements has a unique and stable molecular structure, and the aerogel state formed is better maintained, has relatively strong stability, and thus prolongs the service life of the sensor. Further, by adjusting the ratio of A and B, the electronic conduction structure inside the gas-sensitive material can be adjusted, thereby adjusting the combination efficiency of the sensitive electrode surface and the aldehyde gas, and further adjusting the reaction rate of the aldehyde gas on the electrode surface, which can further improve the selectivity and sensitivity of the sensor. Therefore, by using the gas-sensitive material provided in the present application, the sensitivity, selectivity and service life of the solid-state electrolyte gas sensor can be improved.

[0032] It can be understood that the valence of each element in A x B y (TiO3) n must satisfy the charge balance, for example, the valence of A is +a, the valence of B is +b, the valence of Ti is +4, and the valence of O is -2, so ax+by+4n=6n. When one of A and B is Fe, the valence of Fe can be +2 or +3; when one of A and B is Zn, the valence of Zn can be +2, and the like.

[0033] According to some embodiments of the present application, x:y=(1-10):(1-10). For example, it can be 1:1, 1:5, 1:10, 5:1, 10:1, 2:3, 2:5, etc. By limiting the molar ratio of x and y within the above range, the internal electron conduction structure of the gas sensitive material is adjusted, so as to adjust the binding efficiency of the sensitive electrode surface to the aldehyde gas, and then the reaction rate of the aldehyde gas on the electrode surface can be adjusted. Thus, it is beneficial to improve the sensitivity, selectivity and service life of the solid-state electrolyte gas sensor.

[0034] According to some embodiments of the present application, x satisfies: 0

[0035] According to some embodiments of the present application, the porosity of the gas sensitive material is 5%-70%. For example, it can be 5%, 10%, 20%, 40%, 70%, etc. By limiting the porosity of the gas sensitive material within the above range, more channels can be provided, which is beneficial to accelerate the diffusion of the gas and reduce the consumption of the diffusion process of the to-be-detected gas in the gas sensitive material. It can also increase the contact opportunity of the gas and the active sites of the gas sensitive material, accelerate the response speed and reduce the lower limit of detection, which is beneficial to improve the sensitivity of the solid-state electrolyte gas sensor.

[0036] In the second aspect of the present application, a method for preparing the above-mentioned gas sensitive material is provided. According to an embodiment of the present application, the method comprises:

[0037] S1, preparing a metal titanate wet gel.

[0038] In this step, the preparation method of the metal titanate wet gel is not particularly limited. For example, chemical coprecipitation method, hydrothermal method, high-temperature solid-phase synthesis method, sol-gel method, etc. can be used, and a person skilled in the art can make a flexible selection according to the needs. According to one specific embodiment of the present application, a sol-gel method is used to obtain a metal titanate wet gel. Specifically, the metal alkoxide is dissolved in a solvent, and water is added under controlled conditions to carry out a hydrolysis reaction. The hydroxyl compound generated after hydrolysis is further converted into a three-dimensional network structure sol through a condensation reaction, and finally converted into a metal titanate wet gel. The chemical formula of the metal titanate wet gel is A x B y (TiO3) naH2O, A and B are both transition metal elements, each including one of Fe, Co, Ni, Cu, Zn, Mn, Cd, etc., wherein x:y=(1-100):(1-100), n satisfies: 1n400, a satisfies: 1a15.

[0039] S2, drying the metal titanate wet gel under a vacuum condition to obtain a dry gel.

[0040] In this step, the metal titanate wet gel is dried under a vacuum condition to remove the solvent and water therein, so as to obtain a dry gel.

[0041] According to some embodiments of the present application, the drying temperature is 25-90℃. For example, it can be 25℃, 30℃, 50℃, 70℃, 90℃, etc. By limiting the drying temperature within the above range, the shrinkage of the gel network caused by the rapid evaporation of the solvent can be reduced, which helps to maintain the pore structure of the gas-sensitive material and avoid the destruction of the pore structure, so as to maintain the high specific surface area of the gas-sensitive material, and further improve the sensitivity, selectivity and service life of the solid-state electrolyte gas sensor.

[0042] According to some embodiments of the present application, the mass fraction of water in the dry gel is not more than 45% based on the total mass of the dry gel. For example, it can be 1%, 10%, 20%, 40%, 45%, etc. The water in the dry gel will evaporate in the subsequent calcination process. By limiting the mass fraction of water in the dry gel within the above range, the high water content in the subsequent calcination process can be avoided, which can prevent the rapid evaporation from causing the surface cracking or internal structure collapse of the gas-sensitive material, and further help to maintain the structural integrity of the gas-sensitive material during the calcination process, improve the gas adsorption capacity and sensing performance of the gas-sensitive material, and improve the sensitivity of the solid-state electrolyte sensor.

[0043] S3, calcining the dry gel to obtain a gas-sensitive material.

[0044] In this step, the organic components and water in the wet gel are volatilized by calcining the dry gel, which can form a porous structure and obtain a gas-sensitive material with a loose porous structure.

[0045] According to some embodiments of the present application, the calcination temperature is 400-1200℃. For example, it can be 400℃, 600℃, 800℃, 1000℃, 1200℃, etc. By limiting the calcination temperature within the above range, the pore structure of the gas-sensitive material can be optimized under the condition of ensuring the complete sintering of the gas-sensitive material, which is conducive to obtaining a gas-sensitive material with a loose porous structure, and further improves the sensitivity of the solid-state electrolyte gas sensor.

[0046] According to some embodiments of the present application, the calcination time is 0.5h-12h. For example, it can be 0.5h, 1h, 5h, 10h, 12h, etc. By limiting the calcination time within the above range, the pore structure of the gas sensitive material can be further optimized, which is conducive to obtaining a gas sensitive material with a loose porous structure, and thus the sensitivity of the solid electrolyte gas sensor can be improved.

[0047] In a third aspect of the present application, the present application provides a solid electrolyte gas sensor comprising the above-mentioned gas sensitive material or the gas sensitive material prepared by the above-mentioned method according to the embodiments of the present application. Thus, the solid electrolyte gas sensor has higher sensitivity and longer service life, and the solid electrolyte gas sensor has better selectivity to aldehyde gas.

[0048] According to some embodiments of the present application, referring to Figure 1 , the solid electrolyte gas sensor 100 sequentially comprises a sensitive electrode 40, a solid electrolyte layer 30, a reference electrode 50, an insulating substrate layer 10 and a heating electrode layer 20, the reference electrode 50 and the sensitive electrode 40 are respectively arranged in a strip shape at both ends of the solid electrolyte layer 30, the heating electrode layer 20 is arranged on the side of the solid electrolyte layer 30 away from the reference electrode 50 and the sensitive electrode 40, and the insulating substrate layer 10 is arranged on the side of the heating electrode layer 20 away from the solid electrolyte layer 30; wherein the material of the sensitive electrode comprises the above-mentioned gas sensitive material, the gas sensitive material comprises A x B y (TiO3) n , x:y=(1-100):(1-100), 1≤n≤400, A and B each comprise any one of Fe, Co, Ni, Cu, Zn, Mn and Cd.

[0049] According to the embodiments of the present application, the chemical structural formula of the gas sensitive material is A x B y (TiO3) n , A and B each comprise any one of transition metal elements such as Fe, Co, Ni, Cu, Zn, Mn and Cd. Taking Ni and Co as an example, the d orbital of Ni usually has 8 electrons, and when it exists in the form of Ni 2+ , it loses two electrons, resulting in a change in the electron distribution in the d orbital, inducing electronic conductivity. By doping low-valence Ni 2+ in the gas sensitive material, oxygen defect sites can be generated to cause high-concentration electronic conduction, which can compensate for the hole accumulation layer in the gas sensitive material, thereby increasing the rate of adsorbing aldehyde gas and accepting electrons by the gas sensitive material, and thus the selectivity of the sensor to aldehyde gas can be improved. And cobalt exists in the form of Co4+ When the gas sensitive material exists in the form of A (TiO3) B, it has a lower oxygen ion migration activation energy, so that the energy required for oxygen ion migration at this position is lower, thereby promoting the migration of oxygen ions, helping to improve the adsorption and desorption process of oxygen, and thus helping to improve the sensitivity of the sensor. Moreover, A and B are selected to be transition metal elements to form a transition metal titanate, which has a unique and stable molecular structure, and the aerogel state formed is better maintained, has relatively strong stability, and thus prolongs the service life of the sensor. Further, by adjusting the ratio of A and B, the internal electronic conduction structure of the gas sensitive material can be adjusted, thereby adjusting the binding efficiency of the sensitive electrode surface and the aldehyde gas, and thus the reaction rate of the aldehyde gas on the electrode surface can be adjusted, so as to further improve the selectivity and sensitivity of the sensor. Thus, by using the gas sensitive material provided in the present application, the sensitivity, selectivity and service life of the solid-state electrolyte gas sensor can be improved. Thus, the solid-state electrolyte gas sensor has high sensitivity and long service life, and the solid-state electrolyte gas sensor has good selectivity to aldehyde gas.

[0050] Optionally, the preparation method of the sensitive electrode comprises: mixing A x B y (TiO3) n The gas sensitive material is mixed with water or an alcohol reagent to form a slurry, and a strip-shaped sensitive electrode with a thickness of 0.001mm-2.5mm is prepared on the solid-state electrolyte layer by using a conventional drop coating or screen printing method or a magnetron sputtering method. After the preparation of the sensitive electrode, the substrate is sintered at 1000℃ for 30min to form good contact between the sensitive electrode and the solid-state electrolyte layer.

[0051] Optionally, the reference electrode is preferably a platinum electrode, and the platinum slurry can be printed or sputtered on the surface of the solid-state electrolyte layer.

[0052] Optionally, the solid-state electrolyte layer comprises a ZrO2 substrate, wherein Y2O3 is doped, and the doping mass ratio of Y2O3 is 0-20%.

[0053] Further, based on the solid-state electrolyte and A x B y (TiO3) nThe basic working principle of the gas sensor made of the sensitive electrode material is a hybrid solid electrolyte sensor. Specifically, when the gas sensor is exposed to the environment of the gas to be detected (such as aldehyde gas), the formaldehyde diffuses through the sensitive electrode layer to reach the three-phase reaction interface (TPB) of the gas / sensitive material / electrolyte, and the gas reaching the TPB simultaneously undergoes an electrochemical reduction reaction (1) and an oxidation reaction (2) on the interface to form a local galvanic cell. When the reaction rates of (1) and (2) are equal, the reaction reaches equilibrium, and a hybrid potential is formed on the sensitive electrode, which is the difference between the potential of the reference electrode and the detection signal of the sensor.

[0054] Cathode reaction: O2+ 4e- = 2O 2- (1)

[0055] Anode reaction: (CH2) n CHO + O 2- → CO2+ H2O + 2e- (2)

[0056] However, before the molecules to be detected reach the three-phase interface, a part of the gas molecules will participate in the gas-phase catalytic reaction, which will affect the sensitivity of the sensor. Therefore, the gas-sensitive material provided in the present application adjusts the loose porous structure of the gas-sensitive material, which provides more channels to allow the gas molecules to quickly diffuse to the inside of the material, accelerates the gas diffusion speed, and the loose porous structure also increases the surface area of the gas-sensitive material, which can provide more active sites for the adsorption and reaction of gas molecules. Therefore, the high specific surface area and porous structure can improve the detection ability of low-concentration gas, which is beneficial to improve the sensitivity of the solid electrolyte gas sensor.

[0057] In a fourth aspect of the present application, a refrigerator is provided. According to the embodiments of the present application, the refrigerator comprises the solid electrolyte gas sensor of the third aspect, which is used for detecting the odor gas in the refrigerator, and feeding back the overall situation of the gas in the refrigerator as a basis for judging the state of the food in the refrigerator.

[0058] The solutions of the present disclosure will be explained below in conjunction with the embodiments. Those skilled in the art will understand that the following embodiments are only used to illustrate the present disclosure and should not be regarded as limiting the scope of the present disclosure. If the specific techniques or conditions are not specified in the embodiments, the techniques or conditions described in the literature in the art or according to the product instructions are used. If the reagents or instruments are not specified by the manufacturer, they are all conventional products that can be obtained by purchase.

[0059] Example 1

[0060] 1. Preparation of the gas-sensitive material:

[0061] 1) The metal titanate wet gel is prepared by sol-gel method. Specifically, analytical pure cobalt nitrate and nickel nitrate are added to anhydrous ethanol and stirred constantly to prepare a transparent solution containing cobalt ions and nickel ions, so that the molar ratio of cobalt ions to nickel ions is 2:3. Analytical pure tetrabutyl titanate is added to the solution and stirred constantly. Then, citric acid is added to the solution, so that the molar ratio of citric acid to all cations is 0.7:1. Finally, water and ethyl acetone are added to the solution in a volume ratio of 5:1 and 7:1 respectively, and stirred constantly. The metal titanate wet gel is formed after being left to stand.

[0062] 2) The obtained metal titanate wet gel is dried at 80°C under vacuum for 24 hours to obtain a dry gel.

[0063] 3) The obtained dry gel is placed in an oven and sintered at 800°C for 1 hour by programmed temperature rising to obtain a solid electrolyte gas sensitive material Co2Ni3(TiO3)7 with a porosity of 45%.

[0064] 2. Preparation of the solid electrolyte gas sensor:

[0065] 1) A platinum reference electrode in the shape of a narrow strip is coated on one side of the solid electrolyte substrate by using platinum paste (or a narrow strip of platinum film is directly plated as the reference electrode by using a magnetron sputtering method or the like);

[0066] 2) A platinum dot is made on the other side by the method described in 1);

[0067] 3) Meanwhile, two Pt wires are folded and adhered to the middle position of the reference electrode and the Pt dot as electrode leads. Subsequently, the solid electrolyte substrate is sintered at 1000°C for 30 minutes.

[0068] 4) The Co2Ni3(TiO3)7 gas sensitive material is thoroughly mixed with a proper amount of deionized water to form a slurry with a mass concentration of 5 mg / mL. The slurry is coated on the Pt dot to form a strip-shaped sensitive electrode (this step can be performed by direct drop coating, spin coating or screen printing or the like to form the sensitive electrode). Then, the sensitive electrode is sintered at 800°C for 2 hours in a muffle furnace to ensure good contact between the sensitive electrode and the solid electrolyte substrate.

[0069] 5) In order to provide the required working temperature for the solid electrolyte gas sensor, a heating plate is adhered to the back of the solid electrolyte substrate. The adhered substrate is placed under an oven lamp for 1-2 hours to ensure that the heating plate is tightly adhered. Finally, a planar solid electrolyte gas sensor element is obtained.

[0070] The gas sensitive materials in Examples 2-14 and Comparative Examples 1-3 are different from Example 1 in some parameters.

[0071] The partial parameters of the gas sensitive materials of Examples 1-14 and Comparative Examples 1-3 are shown in Table 1.

[0072] Table 1

[0073]

[0074]

[0075] Test and Analysis

[0076] The solid electrolyte gas sensors obtained in the above Examples 1-14 and Comparative Examples 1-3 were respectively subjected to sensitivity test, selectivity test and service life performance test under the same conditions. The specific test methods are as follows:

[0077] The sensitive performance of the gas sensor in the examples was tested based on the conventional dynamic test method. The sensitive electrode and the reference electrode were respectively connected to the positive and negative electrodes of the test instrument. The leads at both ends of the heating plate were connected to the positive and negative electrodes on the linear direct current power supply, and the working temperature of the gas sensor provided by the heating plate was adjusted by controlling the current size, and the actual working temperature of the sensor was calibrated by an infrared thermal imager.

[0078] The specific sensitive performance test process of the sensor is as follows: 1L of the gas testing bottle is used as the test space, and pure air is filled into the gas testing bottle by a gas pump before the test starts. The aged sensor is placed in the air bottle, and when the voltage value reaches a stable state, the voltage value at this time is recorded as the response value V 空气 of the sensor in air. Then the required concentration of the test gas is introduced into the gas testing bottle until the gas in the gas testing bottle is completely replaced. When the sensor voltage value reaches a stable state, the voltage value at this time is recorded as the response value V 待测气体 of the sensor in the test gas. Subsequently, air is replaced into the test bottle again, and the sensor returns to a stable state again. At this time, a complete response and recovery test process is completed.

[0079] Sensitivity test: the response value (ΔV) of the sensor to a certain test gas is defined as the ratio of the difference between the potential response values of the sensor in the test gas and in air at a certain concentration to the initial value, that is, ΔV / V 空气 = (V 待测气体 -V 空气 ) / V 空气 . The sensitivity of the sensor is defined as the response value of the sensor to 1 ppm gas.

[0080] Selectivity test: the selectivity test method of the sensor is consistent with the above dynamic test method. The response of the sensor to other gases at a concentration of 20 ppm is tested, and compared with the response of the sensor to 20 ppm aldehyde gas. The greater the difference, the better the selectivity of the sensor.

[0081] Service life performance test: the selectivity test method of the sensor is consistent with the dynamic test method described above, and 10 ppm formaldehyde is tested for 100 times of repeated test. The smaller the response value deviation of the sensor during the test, the more stable the sensor and the longer the service life.

[0082] Figure 2 The SEM image of the gas sensitive material of Example 1 is shown. From the figure, it can be obtained that the gas sensitive material prepared by Example 1 is accumulated by micron and nanometer particles, and presents a loose and porous structure, which is beneficial to the rapid diffusion of the to-be-tested gas in the sensitive electrode layer.

[0083] Figure 3 The EDS element distribution map of the gas sensitive material of Example 1 is shown. From the figure, it can be obtained that the three elements in the gas sensitive material exist and are uniformly distributed in the material.

[0084] Figure 4 The response curve of the solid electrolyte gas sensor of Example 1 to various aldehyde gases is shown. From the figure, it can be obtained that the sensor has good response to various aldehyde gases.

[0085] Figure 5 The response fitting curve of the solid electrolyte gas sensor of Example 1 to formaldehyde is shown. From the figure, it can be obtained that the sensor has good response to formaldehyde with a concentration of 2 PPM-50 PPM, and the response is linear, which can be used as a basis for quantitative detection.

[0086] Figure 6 The response selectivity curve of the solid electrolyte gas sensor of Example 1 to formaldehyde is shown. From the figure, it can be obtained that in the response signal of the sensor to 20 ppm gas, the response of formaldehyde is the highest, and the sensor has specific selectivity to formaldehyde, so the sensor has small interference in actual application.

[0087] Figure 7 The 100 times of response test of the solid electrolyte gas sensor of Example 1 to 10 ppm formaldehyde is shown. From the figure, it can be obtained that after 100 times of test, the response of the sensor remains basically unchanged, which proves that the sensor works stably and has long service life.

[0088] The test results are shown in Table 2.

[0089] Table 2

[0090]

[0091] Combining Table 1 and Table 2, it can be obtained that compared with Comparative Examples 1-3, the solid electrolyte gas sensor of Examples 1-13 has more advantages in response value and detection limit.

[0092] In the description of the specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", "some implementations" or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are contained in at least one embodiment or example of the present application. In the specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Also, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. Furthermore, the person skilled in the art can combine and combine the different embodiments or examples described in the specification and the features of the different embodiments or examples, without contradiction.

[0093] Although the embodiments of the present application have been shown and described above, it is understood that the above-described embodiments are exemplary and are not to be construed as limiting the present application, and the person skilled in the art can make changes, modifications, replacements and variations to the above-described embodiments within the scope of the present application.

Claims

1. A gas-sensitive material, characterized in that, The gas-sensitive material includes A x B y (TiO3) n , where x:y=(1-100):(1-100), 1≤n≤400, and A and B each include any one of Fe, Co, Ni, Cu, Zn, Mn and Cd.

2. The gas-sensitive material according to claim 1, characterized in that, x:y = (1-10):(1-10); and / or, x satisfies: 0 < x ≤ 100, y satisfies: 0 < y ≤ 100.

3. The gas-sensitive material according to claim 1 or 2, characterized in that, The porosity of the gas-sensitive material is 5%-70%.

4. A method for preparing the gas-sensitive material according to any one of claims 1-3, characterized in that, include: Preparation of wet metal titanate gels; The wet metal titanate gel was dried under vacuum conditions to obtain a dry gel. The dry gel was calcined to obtain a gas-sensitive material.

5. The method according to claim 4, characterized in that, The drying temperature is 25℃-90℃.

6. The method according to claim 4, characterized in that, Based on the total mass of the dry gel, the mass percentage of water shall not exceed 45%.

7. The method according to claim 4, characterized in that, The roasting temperature is 400℃-1200℃.

8. The method according to claim 4, characterized in that, The roasting time is 0.5h-12h.

9. A solid electrolyte gas sensor, characterized in that, The solid electrolyte gas sensor comprises the gas-sensitive material according to any one of claims 1-3 or the gas-sensitive material prepared by any one of claims 4-8.

10. A refrigerator, characterized in that, The refrigerator includes the solid electrolyte gas sensor as described in claim 9.

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