Carbon dioxide gas-sensitive material based on platinum-modified neodymium-iron-magnesium oxide as well as preparation method and application of carbon dioxide gas-sensitive material

Abstract

The invention discloses a carbon dioxide gas-sensitive material based on platinum-modified neodymium-iron-magnesium oxide as well as a preparation method and application thereof, and relates to the technical field of carbon dioxide gas detection. The chemical formula of the carbon dioxide gas-sensitive material based on the platinum-modified neodymium-iron-magnesium oxide is Xwt% of Pt-NdFe1-yMgyO3, in the formula, 0 lt; x is less than or equal to 10, 0lt; and y < = 0.5. On the basis of an NdFeO3 material, a Pt element is adopted for surface modification while an Mg element is adopted for doping, and the carbon dioxide gas-sensitive material based on the platinum-modified neodymium-iron-magnesium oxide is obtained. Through composite doping modification of Mg and Pt elements, the working temperature of the platinum-modified neodymium-iron-magnesium oxide-based carbon dioxide gas-sensitive material during detection of carbon dioxide gas is reduced. Specifically, at the working temperature of 160 DEG C, the response to 10000 ppm of carbon dioxide gas is 6.24.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon dioxide gas detection, and in particular to a carbon dioxide gas-sensitive material based on platinum-modified neodymium iron magnesium oxide, and a preparation method and application thereof. Background Art

[0002] As global climate change becomes increasingly serious, carbon dioxide, as one of the main greenhouse gases, has received widespread attention. The increase in carbon dioxide concentration not only leads to global warming, but also has a negative impact on human health. Therefore, how to effectively monitor the concentration of carbon dioxide in the atmosphere has become an important issue that needs to be solved urgently.

[0003] At present, the technologies for detecting carbon dioxide concentration mainly include infrared spectroscopy, electrochemical sensors and gas-sensitive material sensors. Among them, gas-sensitive material sensors have gradually become one of the hot spots in gas sensor research due to their advantages such as small size, low cost, easy integration and fast response speed. The role of gas-sensitive materials in carbon dioxide detection is mainly manifested in that when the surface of the material comes into contact with carbon dioxide gas, the electrical properties of the material will change, and then the presence and concentration of the gas will be detected based on these changes. The gas-sensitive materials that can be used for gas sensors mainly include: n-type semiconductors with electrons as carriers and p-type semiconductors with holes as carriers. Among them, perovskite-type composite oxides are typical p-type semiconductors. They are formed by a variety of metals, have dual conductive properties of ion conduction and electronic conduction, and have a stable structure. They can allow many metal elements to be doped and modified, and have become a current research hotspot.

[0004] In the prior art, the paper "Study on the Gas Sensitivity of Perovskite Nanocrystalline Materials to Acetone-based CO2 Gas" discloses PrFeO3 materials, 3wt%-PrFeO3 materials, and Pr 0.9 Ca 0.1The responses of the FeO3 material to 2000 ppm of CO2 gas are 1.15, 1.40, and 1.38 respectively. However, the optimal working temperature of the above-prepared material is 200 °C. "CO2 sensing properties and mechanism of PrFeO3 and NdFeO3 thick film sensor" (Yanping Chen, Journal of Rare Earths 37 (2019) 80-87) discloses the preparation of nanocrystalline powder NdFeO3 by the sol-gel method, with a nanometer diameter of 10-110 nm, an optimal working temperature of 200 °C, and a response to 9000 ppm of CO2 gas of 3.75 at this working temperature. Thus, although the above gas-sensitive materials can be used to detect carbon dioxide gas, the working temperatures of the above gas-sensitive materials are all 200 °C, which is relatively high. And too high a working temperature will reduce the sensitivity and response speed of the gas-sensitive sensor and increase the energy consumption of the gas-sensitive sensor.

[0005] Therefore, based on the NdFeO3 material, how to dope and modify it to obtain a gas-sensitive material that can be used to detect carbon dioxide gas, so as to reduce the working temperature of the gas-sensitive material and improve the response of the gas-sensitive material to carbon dioxide gas, has become an important topic in the current technical field. Summary of the Invention

[0006] In view of the above prior art, the object of the present invention is to provide a carbon dioxide gas-sensitive material based on platinum-modified neodymium iron magnesium oxide, its preparation method and application. The chemical formula of the carbon dioxide gas-sensitive material based on platinum-modified neodymium iron magnesium oxide is Xwt% Pt-NdFe 1-y Mg y O3, where 0 < x ≤ 10 and 0 < y ≤ 0.5. On the basis of the NdFeO3 material, the present invention uses Mg element for doping and Pt element for modification at the same time to obtain a carbon dioxide gas-sensitive material based on platinum-modified neodymium iron magnesium oxide. Through the composite doping modification of Mg element and Pt element, while reducing the working temperature of the material for carbon dioxide detection, good response and selectivity are ensured. Specifically, at a working temperature of 160 °C, its response value to 10000 ppm of carbon dioxide gas is 6.24.

[0007] To achieve the above object, the present invention adopts the following technical solutions: In the first aspect of the present invention, a carbon dioxide gas-sensitive material based on platinum-modified neodymium iron magnesium oxide is provided. The chemical formula of the carbon dioxide gas-sensitive material based on platinum-modified neodymium iron magnesium oxide is Xwt% Pt-NdFe 1- y Mg yO3, where 0 <x≤10,0<y≤0.5。

[0008] Preferably, the carbon dioxide gas-sensitive material based on platinum-modified neodymium iron magnesium oxide has a nanoparticle structure with an average particle size of 100-220 nm.

[0009] The second aspect of the present invention provides a method for preparing a carbon dioxide gas-sensitive material based on platinum-modified neodymium iron magnesium oxide, comprising the following steps: (1) Mixing neodymium nitrate hexahydrate, iron nitrate and magnesium nitrate to obtain a mixture, dissolving the mixture in dilute nitric acid and stirring, and then adding citric acid solution to obtain a mixed solution; heating the mixed solution at 50-85°C for 2-12 hours and stirring, and cooling to obtain a gel; mixing the gel with anhydrous ethanol and grinding, calcining at 600-1000°C for 3-10 hours, and grinding to obtain neodymium iron magnesium oxide; (2) mixing NdFeMgO and platinum dichloride and grinding them to obtain powder, and calcining the powder at 600-1000°C for 3-10 hours to obtain a carbon dioxide gas-sensitive material based on NdFeMgO modified with platinum; The ratio of the added amounts of neodymium nitrate hexahydrate, ferric nitrate, magnesium nitrate, platinum dichloride, citric acid and dilute nitric acid is (0.01-5) mol: (0.05-5) mol: (0.01-5) mol: (0.01-100) g: (20-100) g: (50-200) mL.

[0010] Preferably, in step (1), the citric acid solution is obtained by mixing citric acid and deionized water in a solid-liquid ratio of (0.8-1.2) g:20 mL.

[0011] Preferably, in step (1), the mass fraction of dilute nitric acid is 8-9%.

[0012] Preferably, in step (1), the heating method is water bath heating.

[0013] Preferably, in step (1), the stirring speed is 500-1000 r / min.

[0014] Preferably, in step (1), the mass ratio of gel to anhydrous ethanol is 1 g:(2.5-3.5) g.

[0015] Preferably, the grinding time is 2-6 hours.

[0016] The third aspect of the present invention provides the use of the above-mentioned carbon dioxide gas-sensitive material based on platinum-modified neodymium iron magnesium oxide in detecting carbon dioxide gas.

[0017] Preferably, the carbon dioxide gas concentration is 5000-15000 ppm.

[0018] The fourth aspect of the present invention provides the use of the above-mentioned carbon dioxide gas-sensitive material based on platinum-modified neodymium iron magnesium oxide in the preparation of a carbon dioxide gas-sensitive sensor.

[0019] Preferably, the carbon dioxide gas sensor is prepared by the following method: A carbon dioxide gas-sensitive material based on platinum-modified neodymium iron magnesium oxide, deionized water and pinene alcohol are mixed in the ratio of (1-5) g: (3-15) mL: (1-5) mL to obtain a slurry; the slurry is spin-coated on an alumina substrate to form a gas-sensitive film with a thickness of 100-300 μm, and the gas-sensitive film is aged at 200-240° C. for 10-24 hours to obtain a carbon dioxide gas-sensitive sensor.

[0020] Preferably, the operating temperature of the carbon dioxide gas sensor is 160°C.

[0021] Beneficial effects of the present invention: The present invention adopts a sol-gel method, uses hexahydrated neodymium nitrate, ferric nitrate, and magnesium nitrate as reaction raw materials to prepare neodymium iron magnesium oxide, and then mixes neodymium iron magnesium oxide and platinum dichloride and calcines them to obtain a carbon dioxide gas-sensitive material based on neodymium iron magnesium oxide modified by platinum. The present invention introduces Mg elements on the B-site lattice of the neodymium ferrite material to provide more abundant oxygen vacancies, and uses Pt elements for surface modification to enhance catalytic performance. The neodymium ferrite material is doped and modified with Pt elements and the working temperature is reduced, and the co-doping of the two elements has a synergistic effect in improving its response value to CO2 gas. Specifically, the optimal working temperature of the carbon dioxide gas-sensitive material based on platinum-modified neodymium iron magnesium oxide prepared by the present invention is 160°C. At a working temperature of 160°C, the carbon dioxide gas-sensitive material based on platinum-modified neodymium iron magnesium oxide has a response of 6.24 to 10000ppm of CO2 gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 : XRD pattern of the carbon dioxide gas-sensitive material based on platinum-modified neodymium iron magnesium oxide prepared in Example 1; Figure 2 : SEM image of the carbon dioxide gas-sensitive material based on platinum-modified neodymium iron magnesium oxide prepared in Example 1; Figure 3 : EDS Mapping diagram of platinum and magnesium in the carbon dioxide gas-sensitive material based on platinum-modified neodymium iron magnesium oxide prepared in Example 1; Figure 4 : The relationship between the gas-sensing performance of the materials obtained in Example 1 and Comparative Examples 1-3 to 10000 ppm carbon dioxide gas and temperature; Figure 5 : Schematic diagram of the response of the carbon dioxide gas-sensitive material based on platinum-modified neodymium iron magnesium oxide prepared in Example 1 to various gases such as CO2; Figure 6 : Schematic diagram of the long-term gas-sensing stability of the carbon dioxide gas-sensitive material based on platinum-modified neodymium iron magnesium oxide prepared in Example 1 to 10,000 ppm of carbon dioxide gas; Figure 7 : Relationship diagram between the gas-sensing performance and humidity of the carbon dioxide gas-sensitive material based on platinum-modified neodymium iron magnesium oxide prepared in Example 1 to 10,000 ppm of carbon dioxide gas. Detailed implementation manners

[0023] It should be noted that the following detailed descriptions are all illustrative and are intended to provide further explanations of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present application belongs.

[0024] Gas-sensitive materials have the advantages of small volume, low cost, easy integration, and fast response speed, and have become one of the best materials for detecting carbon dioxide gas. In the prior art, the NdFeO3 material is disclosed as a gas-sensitive material for detecting carbon dioxide gas. When the NdFeO3 material is used for detecting carbon dioxide gas, its optimal working temperature is 200 °C. At this working temperature, its response value to 9,000 ppm of carbon dioxide gas is 3.75. However, if the working temperature of the gas-sensitive sensor is too high, it will lead to increased energy consumption and decreased sensitivity.

[0025] Based on this, the present invention provides a carbon dioxide gas-sensitive material based on platinum-modified neodymium iron magnesium oxide. The chemical formula of the carbon dioxide gas-sensitive material based on platinum-modified neodymium iron magnesium oxide is Xwt% Pt-NdFe 1-y Mg y O3, where 0 < x ≤ 10 and 0 < y ≤ 0.5. On the basis of neodymium iron oxide neodymium ferrite, while using the Mg element to perform B-site doping on neodymium ferrite, the surface of neodymium ferrite is modified with Pt, and the prepared carbon dioxide gas-sensitive material based on platinum-modified neodymium iron magnesium oxide reduces the working temperature, and the co-doping of the Mg element and the Pt element shows excellent sensitivity and specificity in improving the detection of carbon dioxide gas. Specifically, the optimal working temperature of the carbon dioxide gas-sensitive material based on platinum-modified neodymium iron magnesium oxide is 160 °C. At the working temperature of 160 °C, its response to 10,000 ppm of CO2 gas is 6.24.

[0026] The present invention is based on NdFeO3 material, and Mg element is doped on the B-site lattice of NdFeO3 material. The doping of Mg element can change the Fe-O bond length and bond angle in the crystal structure, increase the oxygen vacancy concentration and the degree of lattice distortion, and this lattice adjustment optimizes the surface charge distribution and local electronic structure of the material, and significantly enhances the physical adsorption capacity and chemical reaction activity of the material surface to CO2 molecules. At the same time, Pt element is also used for surface modification. The Pt element loaded on the surface reduces the reaction energy barrier of CO2 decomposition through catalytic effect, and promotes the formation and regeneration of oxygen vacancies, thereby achieving a rapid dynamic balance between CO2 molecules and surface active sites.

[0027] The B-site doping of Mg provides the material with more oxygen vacancies, improves electron mobility, and enhances the initial capture capability of CO2 molecules; while the surface modification of Pt elements can promote the dissociation and reduction reaction of CO2 molecules by enhancing catalytic performance, forming a gas-sensitive synergistic mechanism with oxygen vacancies as the core. This mechanism significantly improves the response value of the material to CO2, while effectively suppressing the response to CO and other interfering gases, reflecting the high selectivity to CO2.

[0028] In addition, the particle size of the material prepared by the present invention is optimized at the nanoscale, further increasing the specific surface area and providing more active sites for the adsorption and reaction of gas molecules. Combined with the synergistic effect of Pt and Mg elements, the response value of the material to CO2 at a temperature of 160°C reaches 6.24, showing excellent sensitivity, selectivity and rapid response characteristics.

[0029] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below in conjunction with specific embodiments.

[0030] The experimental materials used in the embodiments of the present invention are all conventional experimental materials in the art and can be purchased through commercial channels.

[0031] Example 1: Carbon dioxide gas-sensitive material based on platinum-modified neodymium iron magnesium oxide 8 wt% Pt-NdFe 0.8 Mg 0.2 Preparation method of O3 (1) Mix citric acid and deionized water at a solid-liquid ratio of 1 g:20 mL, stir and completely dissolve to obtain a citric acid solution; then mix neodymium nitrate hexahydrate, iron nitrate and magnesium nitrate to obtain a mixture, dissolve the mixture in dilute nitric acid with a mass fraction of 8.5% and stir, then slowly add the citric acid solution to obtain a mixed solution, heat the mixed solution in a water bath at 80°C for 10 h and stir at a stirring speed of 500 r / min, and obtain a gel after cooling; mix the gel with anhydrous ethanol at a mass ratio of 1 g:3 g and grind for 3 h, then calcine at 900°C for 8 h and grind for 3 h to obtain neodymium iron magnesium oxide NdFe 0.8 Mg 0.2 O3; (2) NdFe 0.8 Mg 0.2 O3 and platinum dichloride were mixed and ground for 3 hours to obtain a powder, which was then calcined at 900 ° C for 8 hours to obtain a carbon dioxide gas-sensitive material based on platinum-modified neodymium iron magnesium oxide 8 wt% Pt-NdFe 0.8 Mg 0.2 O3; The ratio of the added amounts of neodymium nitrate hexahydrate, ferric nitrate, magnesium nitrate, platinum dichloride, citric acid and dilute nitric acid is 43.835 g: 19.3488 g: 2.966 g: 2.66 g: 60 g: 60 mL.

[0032] Example 2: Carbon dioxide gas-sensitive material based on platinum-modified neodymium iron magnesium oxide 10 wt% Pt-NdFe 0.6 Mg 0.4 Preparation method of O3 (1) Mix citric acid and deionized water in a solid-liquid ratio of 1.2 g: 20 mL, and stir to completely dissolve to obtain a citric acid solution; mix neodymium nitrate hexahydrate, ferric nitrate, and magnesium nitrate to obtain a mixture, dissolve the mixture in 8% by mass dilute nitric acid and stir, then slowly add the citric acid solution to obtain a mixed solution, heat the mixed solution in a water bath at 50°C for 12 h and stir at a stirring speed of 600 r / min, and obtain a gel after cooling, mix the gel with anhydrous ethanol in a mass ratio of 1 g: 3.5 g and grind for 2 h, then calcine at 600°C for 10 h, and grind for 2 h to obtain neodymium iron magnesium oxide NdFe 0.6 Mg 0.4 O3; (2) NdFe 0.6 Mg 0.4 O3 and platinum dichloride were mixed and ground for 2 hours to obtain a powder, which was then calcined at 600 ° C for 10 hours to obtain a carbon dioxide gas-sensitive material based on platinum-modified neodymium iron magnesium oxide 10 wt% Pt-NdFe 0.6 Mg 0.4 O3; Among them, the added amount ratio of the neodymium nitrate hexahydrate, iron nitrate, magnesium nitrate, platinum dichloride, citric acid and dilute nitric acid is 43.835g:14.5116g:5.932g:3.14g:50g:50mL.

[0033] Example 3: Carbon dioxide gas-sensitive material based on platinum-modified neodymium iron magnesium oxide 2 wt% Pt-NdFe 0.9 Mg 0.1 Preparation method of O3 (1) Mix citric acid and deionized water at a solid-liquid ratio of 0.8 g:20 mL, and stir to completely dissolve to obtain a citric acid solution; mix neodymium nitrate hexahydrate, iron nitrate, and magnesium nitrate to obtain a mixture, dissolve the mixture in 9% by mass dilute nitric acid and stir, then slowly add the citric acid solution to obtain a mixed solution, heat the mixed solution in a water bath at 85°C for 2 h and stir at a stirring speed of 600 r / min, and obtain a gel after cooling, mix the gel with anhydrous ethanol at a mass ratio of 1 g:2.5 g and grind for 3 h, then calcine at 1000°C for 3 h, and grind for 6 h to obtain neodymium iron magnesium oxide NdFe 0.9 Mg 0.1 O3; (2) NdFe 0.9 Mg 0.1 O3 and platinum dichloride were mixed and ground for 6 hours to obtain a powder, which was then calcined at 1000 ° C for 3 hours to obtain a carbon dioxide gas-sensitive material based on platinum-modified neodymium iron magnesium oxide 2 wt% Pt-NdFe 0.9 Mg 0.1 O3; Among them, the added amount ratio of the neodymium nitrate hexahydrate, iron nitrate, magnesium nitrate, platinum dichloride, citric acid and dilute nitric acid is 43.835g:21.7674g:1.483g:0.69g:50g:50mL.

[0034] Example 4: Preparation of carbon dioxide gas sensor The carbon dioxide gas-sensitive material based on platinum-modified neodymium iron magnesium oxide prepared in Example 1, deionized water and pine alcohol were mixed in an addition ratio of 1 g: 3 mL: 1 mL to obtain a slurry, and the slurry was spin-coated on the surface of an aluminum oxide ceramic tube at a rotation speed of 600 rpm to form a 193 μm gas-sensitive film. The gas-sensitive film was placed in air and aged at 220° C. for 20 h to obtain a carbon dioxide gas sensor.

[0035] Comparative Example 1: Preparation method of neodymium iron oxide NdFeO3 The difference between this comparative example and Example 1 is that magnesium nitrate and platinum dichloride are not added. The specific steps are: Mix citric acid and deionized water at a solid-liquid ratio of 1g:20mL, stir to completely dissolve to obtain a citric acid solution; mix neodymium nitrate hexahydrate and ferric nitrate to obtain a mixture, dissolve the mixture in dilute nitric acid with a mass fraction of 8.5% and stir, then slowly add the citric acid solution to obtain a mixed solution, heat the mixed solution in a water bath at 80°C for 10h and stir at a stirring speed of 500r / min, and obtain a gel after cooling, then mix the gel with anhydrous ethanol at a mass ratio of 1g:3g and grind for 3h, calcine at 900°C for 8h, grind for 3h, and obtain neodymium iron oxide NdFeO3; The ratio of the added amounts of neodymium nitrate hexahydrate, ferric nitrate, citric acid and dilute nitric acid is 43.835 g: 19.3488 g: 60 g: 60 mL.

[0036] Comparative Example 2: Neodymium Iron Magnesium Oxide NdFe 0.8 Mg 0.2 Preparation method of O3 The difference between this comparative example and Example 1 is that no platinum dichloride is added. The specific steps are: Mix citric acid and deionized water at a solid-liquid ratio of 1g:20mL, stir to completely dissolve to obtain a citric acid solution; then mix neodymium nitrate hexahydrate, ferric nitrate and magnesium nitrate to obtain a mixture, dissolve the mixture in dilute nitric acid with a mass fraction of 8.5% and stir, then slowly add the citric acid solution to obtain a mixed solution, heat the mixed solution in a water bath at 80°C for 10h and stir at a stirring speed of 500r / min, and obtain a gel after cooling, mix the gel and anhydrous ethanol at a mass ratio of 1g:3g and grind for 3h, calcine at 900°C for 8h, grind for 3h, and obtain neodymium iron magnesium oxide NdFe 0.8 Mg 0.2 O3; The ratio of the added amounts of neodymium nitrate hexahydrate, ferric nitrate, magnesium nitrate, citric acid and dilute nitric acid is 43.835 g: 19.3488 g: 2.966 g: 60 g: 60 mL.

[0037] Comparative Example 3: Preparation method of platinum-modified neodymium iron oxide 8 wt% Pt-NdFeO3 The difference between this comparative example and Example 1 is that magnesium nitrate is not added. The specific steps are: (1) Mix citric acid and deionized water in a solid-liquid ratio of 1 g:20 mL, and stir to completely dissolve to obtain a citric acid solution; then mix neodymium nitrate hexahydrate and ferric nitrate to obtain a mixture, dissolve the mixture in dilute nitric acid with a mass fraction of 8.5% and stir, then slowly add the citric acid solution to obtain a mixed solution, heat the mixed solution in a water bath at 80°C for 10 h and stir at a stirring speed of 500 r / min, and obtain a gel after cooling, then mix the gel with anhydrous ethanol in a mass ratio of 1 g:3 g and grind for 3 h, calcine at 900°C for 8 h, and grind for 3 h to obtain neodymium iron oxide NdFeO3; (2) Mixing neodymium iron oxide NdFeO3 and platinum dichloride and grinding for 3 hours to obtain a powder, and calcining the powder at 900°C for 8 hours to obtain platinum-modified neodymium iron oxide 8 wt% Pt-NdFeO3; The ratio of the added amounts of neodymium nitrate hexahydrate, ferric nitrate, platinum dichloride, citric acid and dilute nitric acid is 43.835 g: 19.3488 g: 2.66 g: 60 g: 60 mL.

[0038] Test Example 1: Structural Characterization The carbon dioxide gas-sensitive material based on platinum-modified neodymium iron magnesium oxide prepared in Example 1 was 8 wt% Pt-NdFe 0.8 Mg 0.2 O3 was used for structural characterization, and the results were as follows Figure 1-Figure 3 shown.

[0039] Figure 1 The XRD pattern of the carbon dioxide gas-sensitive material based on platinum-modified neodymium iron magnesium oxide prepared in Example 1 is shown in FIG. Figure 1 It can be seen that the crystallization peaks correspond to the (121), (200) and (002) phases of NdFeO3 (No.25-1149). Figure 2 It can be seen that the carbon dioxide gas-sensitive material based on platinum-modified NdFeMg oxide presents a typical nanoparticle structure with a large specific surface area and porosity, and more reaction sites and transmission channels for gas molecules. Figure 3 From the EDS-Mapping diagram of platinum and magnesium elements, it can be seen that Pt and Mg elements exist in the material, which shows that Pt and Mg elements are successfully doped into NdFeO3.

[0040] Test Example 2: Gas Sensing Performance The carbon dioxide gas-sensitive material based on platinum-modified neodymium iron magnesium oxide prepared in Example 1 and the materials prepared in Comparative Examples 1-3 were coated on the sensing film, and their gas-sensitive responses (Rg / Ra) to gases such as CO2 and C2H4 were tested. The results are as follows: Figure 4-Figure 7As shown. Among them, Ra is the resistance of the sensor in the air, and Rg is the resistance of the gas being measured. The experimental environment is: RH is 20%, and the ambient temperature is 20℃.

[0041] Depend on Figure 4 It can be seen that the optimal working temperature of the carbon dioxide gas-sensitive material based on platinum-modified neodymium iron magnesium oxide prepared in the present invention is 160°C. At a working temperature of 160°C, the carbon dioxide gas-sensitive material based on platinum-modified neodymium iron magnesium oxide prepared in the present invention 8 wt% Pt-NdFe 0.8 Mg 0.2 The response value of O3 to 10000 ppm CO2 gas is 6.24, the response value of NdFeO3 prepared in Example 1 to 10000 ppm CO2 gas is 1.93, and the response value of NdFeO3 prepared in Example 2 is 0.8 Mg 0.2 The response value of Pt-NdFeO3 to 10000 ppm CO2 gas is 2.51, and the response value of 8 wt% Pt-NdFeO3 prepared in comparative example 3 to 10000 ppm CO2 gas is 4.97. It can be seen that the loading and modification of the surface precious metal Pt of NdFeO3 material and the doping of Mg element at the B position have a synergistic effect in improving the response value of the material to CO2 gas.

[0042] Depend on Figure 5 It can be seen that when exposed to multiple gases, the carbon dioxide gas-sensitive material 8 wt% Pt-NdFe 0.8 Mg 0.2 The selectivity of O3 to 1000ppm CO2 gas is significantly higher than that to gases including C2H4, CH5N, etc. It can be seen that the carbon dioxide gas-sensitive material based on platinum-modified NdFeMg oxide prepared in the present invention has good selectivity to carbon dioxide gas.

[0043] Figure 6 The present invention shows that the carbon dioxide gas-sensitive material 8 wt% Pt-NdFe based on platinum-modified neodymium iron magnesium oxide is prepared 0.8 Mg 0.2 The long-term stability of O3 to 10000ppm CO2 gas. It can be seen from the figure that within one month, the present invention prepared a carbon dioxide gas-sensitive material based on platinum-modified neodymium iron magnesium oxide 8 wt% Pt-NdFe 0.8 Mg 0.2 The response value change rate of O3 to 10000ppm CO2 gas is within 3%, indicating that the material has extremely high long-term stability in gas sensitivity.

[0044] Figure 7The present invention shows that the carbon dioxide gas-sensitive material 8 wt% Pt-NdFe based on platinum-modified neodymium iron magnesium oxide is prepared 0.8 Mg 0.2 The relationship between the gas sensing performance of O3 to 10000 ppm CO2 gas and humidity. Figure 7 It can be seen that with the increase of relative humidity, the gas-sensing performance gradually decreases. When the relative humidity exceeds 40%, the gas-sensing performance drops sharply, but within 40%, the change rate of the carbon dioxide gas-sensing performance of the carbon dioxide gas-sensing material based on platinum-modified neodymium iron magnesium oxide is within 5%, indicating that it has extremely high gas-sensing relative humidity resistance.

[0045] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A carbon dioxide gas-sensitive material based on platinum-modified neodymium iron magnesium oxide, characterized in that: The chemical formula of the carbon dioxide gas-sensitive material based on platinum-modified neodymium iron magnesium oxide is Xwt% Pt-NdFe 1-y Mg y O3, where 0 <x≤10,0<y≤0.5。 2. The method for preparing the carbon dioxide gas-sensitive material based on platinum-modified neodymium iron magnesium oxide according to claim 1, characterized in that: The following steps are involved: (1) Mixing neodymium nitrate hexahydrate, iron nitrate and magnesium nitrate to obtain a mixture, dissolving the mixture in dilute nitric acid and stirring, and then adding citric acid solution to obtain a mixed solution; heating the mixed solution at 50-85°C for 2-12 hours and stirring, and cooling to obtain a gel; mixing the gel with anhydrous ethanol and grinding, calcining at 600-1000°C for 3-10 hours, and grinding to obtain neodymium iron magnesium oxide; (2) mixing NdFeMgO and platinum dichloride and grinding them to obtain powder, and calcining the powder at 600-1000°C for 3-10 hours to obtain a carbon dioxide gas-sensitive material based on NdFeMgO modified with platinum; The ratio of the added amounts of neodymium nitrate hexahydrate, ferric nitrate, magnesium nitrate, platinum dichloride, citric acid and dilute nitric acid is (0.01-5) mol: (0.05-5) mol: (0.01-5) mol: (0.01-100) g: (20-100) g: (50-200) mL.

3. The method for preparing a carbon dioxide gas-sensitive material based on platinum-modified neodymium iron magnesium oxide according to claim 2, characterized in that: In step (1), the mass fraction of dilute nitric acid is 8-9%, and the stirring speed is 500-1000 r / min.

4. The method for preparing a carbon dioxide gas-sensitive material based on platinum-modified neodymium iron magnesium oxide according to claim 2, characterized in that: The grinding time is 2-6h.

5. The method for preparing a carbon dioxide gas-sensitive material based on platinum-modified neodymium iron magnesium oxide according to claim 2, characterized in that: In step (1), the citric acid solution is obtained by mixing citric acid and deionized water in a solid-liquid ratio of (0.8-1.2) g:20 mL.

6. The method for preparing a carbon dioxide gas-sensitive material based on platinum-modified neodymium iron magnesium oxide according to claim 2, characterized in that: In step (1), the mass ratio of gel to anhydrous ethanol is 1 g:(2.5-3.5) g.

7. Use of the carbon dioxide gas-sensitive material based on platinum-modified neodymium iron magnesium oxide according to claim 1 in detecting carbon dioxide gas.

8. The use according to claim 7, characterized in that The carbon dioxide gas concentration is 5000-15000ppm.

9. Use of the carbon dioxide gas-sensitive material based on platinum-modified neodymium iron magnesium oxide according to claim 1 in the preparation of a carbon dioxide gas-sensitive sensor.

10. The use according to claim 9, characterized in that The operating temperature of the carbon dioxide gas sensor is 160°C.

Images