Composite gas sensitive material, preparation method thereof and propane gas sensitive sensor

Abstract

The application relates to a composite gas-sensitive material, a preparation method thereof and a propane gas-sensitive sensor. The composite gas-sensitive material provided by the application comprises a gas-sensitive layer and a modification layer, the modification layer is arranged on the surface of the gas-sensitive layer, the gas-sensitive layer comprises Pd-modified Sn3O4, and the modification layer comprises Ga2O3. Compared with a traditional SnO2 gas-sensitive layer, the oxygen vacancy concentration of Sn3O4 in the gas-sensitive layer provided by the application is large, the carrier concentration is high, and the gas-sensitive layer has good gas-sensitive performance; the gap in the crystal structure of Sn3O4 is larger, and the crystal grain interface energy is higher, which is beneficial to gas adsorption in the gas-sensitive response process. Further, the gas-sensitive layer cooperates with Ga2O3 to improve the specific response to propane. Therefore, the composite gas-sensitive material provided by the application has high sensitivity, high selectivity and a low detection limit.

Description

Technical Field

[0001] This application relates to the field of propane gas detection technology, specifically to a composite gas-sensitive material and its preparation method, and a propane gas-sensitive sensor. Background Technology

[0002] Propane is an organic compound with the chemical formula C3H8. It is a colorless and odorless gas, slightly soluble in water, and soluble in ethanol and ether. It is chemically stable and does not readily undergo chemical reactions. It is commonly used as a refrigerant, internal combustion engine fuel, or a raw material for organic synthesis. Propane has simple asphyxiating and anesthetic effects. Exposure to concentrations below 10% can cause mild dizziness; exposure to high concentrations can lead to anesthesia and loss of consciousness; and exposure to extremely high concentrations can cause asphyxiation. Long-term exposure to low concentrations of propane can cause headaches, dizziness, poor sleep, fatigue, mood swings, and autonomic nervous system dysfunction.

[0003] SnO2 is one of the most widely used propane gas-sensitive materials to date, occupying a central position among metal oxide semiconductor gas-sensitive materials. However, SnO2 materials are limited by their own active sites and carrier concentration characteristics, and do not have a high gas-sensitive response to propane. At the same time, SnO2 materials do not have specific responses to gases such as propane, formaldehyde, acetone, H2, and CO, making it difficult to determine the type of gas based on the sensor's response. Summary of the Invention

[0004] Based on this, this application provides a composite gas-sensitive material and its preparation method, as well as a propane gas-sensitive sensor. The composite gas-sensitive material provided in this application exhibits high sensitivity, high selectivity, and a low detection limit for propane gas.

[0005] A first aspect of this application provides a composite gas-sensitive material, comprising:

[0006] A gas-sensitive layer comprising Pd-modified Sn3O4, wherein the mass percentage of Pd in ​​the Pd-modified Sn3O4 is 2.5% to 4.5%.

[0007] A modification layer is disposed on the surface of the gas-sensitive layer, and the modification layer includes Ga2O3; the modification layer is formed by sputtering Ga2O3 onto the surface of the gas-sensitive layer using a metal mask.

[0008] In one embodiment, the mass percentage of Pd in ​​the Pd-modified Sn3O4 is 3.3% to 3.7%.

[0009] In one embodiment, the thickness of the gas-sensitive layer is 1.5 μm to 2 μm.

[0010] In one embodiment, the thickness of the modification layer is 3 nm to 7 nm.

[0011] A second aspect of this application provides a method for preparing the composite gas-sensitive material described in any embodiment of the first aspect of this application, comprising the following steps:

[0012] The gas-sensitive layer is prepared by spraying and drying a gas-sensitive slurry containing Pd-modified Sn3O4.

[0013] The modification layer is prepared by sputtering Ga2O3 onto the surface of the gas-sensitive layer using a metal mask.

[0014] In one embodiment, the process parameters for sputtering the metal mask include: sputtering power of 100W to 140W.

[0015] In one embodiment, the preparation process of the gas-sensitive slurry containing the Pd-modified Sn3O4 includes:

[0016] Sn3O4 powder, Pd slurry and / or Pd powder are mixed in a dispersion, and then ball milling is performed after mixing and drying to prepare Pd-modified Sn3O4 powder material.

[0017] The Pd-modified Sn3O4 powder material is mixed with an organic slurry to prepare a gas-sensitive slurry containing Pd-modified Sn3O4.

[0018] In one embodiment, the preparation process of the Sn3O4 powder includes:

[0019] SnCl2 solution, oxidant and alkali solution are mixed and reacted at 160℃~200℃ for 10h~14h. After the reaction is completed, the mixture is cooled in a water bath at room temperature and filtered to prepare Sn3O4 powder.

[0020] In one embodiment, the solvent of the organic slurry, by mass percentage, comprises: 50%–70% terpineol, 20%–30% butyl carbitol acetate, and 5%–30% dibutyl phthalate; and the solute of the organic slurry, by mass percentage, comprises: 5%–7% ethyl cellulose, 3%–5% Span 85, 0.5%–1% 1,4-butyrolactone, and 0.5%–1% hydrogenated castor oil.

[0021] A third aspect of this application provides a propane gas sensor, comprising a substrate and a composite gas-sensitive material as described in any embodiment of the first aspect of this application, wherein the composite gas-sensitive material is laminated on the surface of the substrate through the gas-sensitive layer.

[0022] The composite gas-sensitive material provided in this application includes a gas-sensitive layer and a modification layer. The modification layer is disposed on the surface of the gas-sensitive layer. The gas-sensitive layer comprises Pd-modified Sn3O4, and the modification layer comprises Ga2O3. Compared with the traditional SnO2 gas-sensitive layer, the gas-sensitive layer provided in this application has a high oxygen vacancy concentration and a high carrier concentration in Sn3O4, resulting in excellent gas-sensing performance. Furthermore, the Sn3O4 crystal structure has larger interstitial spaces and a higher grain interface energy, which is beneficial for gas adsorption during the gas-sensing response process. Further, the gas-sensitive layer, in conjunction with Ga2O3, can improve the specificity of the response to propane. Therefore, the composite gas-sensitive material provided in this application combines high sensitivity, high selectivity, and a low detection limit. Attached Figure Description

[0023] Figure 1 The response intensity of the gas sensor prepared in Example 1 of this application to different concentrations of propane gas at 200°C;

[0024] Figure 2 The gas sensors prepared in Example 1 and Comparative Examples 1-4 of this application are shown to have a response intensity to 500 ppm propane gas at different operating temperatures.

[0025] Figure 3 The gas sensor prepared in Example 1 of this application shows the response intensity of propane, formaldehyde, acetone, H2 and CO at 200°C to 500 ppm.

[0026] Figure 4 The response intensity of the gas sensors prepared in Examples 1 to 5 of this application to 500 ppm propane gas at different operating temperatures. Detailed Implementation

[0027] The composite gas-sensitive material and its preparation method, as well as the propane gas-sensitive sensor of this application, are further described in detail below with reference to specific embodiments. This application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0029] In this article, "one or more" refers to any one, two or more of the listed items.

[0030] In this application, terms such as "first aspect," "second aspect," "third aspect," "fourth aspect," and "fifth aspect" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, terms such as "first," "second," "third," "fourth," and "fifth" serve only as a non-exhaustive enumeration and should be understood not to constitute a closed limitation on quantity.

[0031] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0032] In this application, numerical ranges are referred to as continuous unless otherwise specified, and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0033] Unless otherwise specified, the percentage content mentioned in this application refers to mass percentage for solid-liquid mixtures and solid-phase-solid mixtures, and volume percentage for liquid-phase-liquid mixtures.

[0034] Unless otherwise specified, all percentage concentrations mentioned in this application refer to the final concentration. The final concentration refers to the proportion of the added component in the system after the addition of that component.

[0035] Unless otherwise specified, the temperature parameters in this application may be either constant temperature processing or processing within a certain temperature range. The constant temperature processing allows for temperature fluctuations within the precision range controlled by the instrument.

[0036] People typically increase the surface active sites and internal carrier concentration of SnO2 materials by altering their morphology, increasing their specific surface area, and doping with elements. However, traditional SnO2 materials are inherently limited by their own characteristics such as the number of active sites and carrier concentration, and therefore do not possess high gas-sensing response. Furthermore, SnO2 materials do not exhibit specific responses to most gases, thus limiting their application in the field of gas-sensing identification.

[0037] Sn3O4, a novel oxide, naturally possesses both +2 and +3 valence states for Sn in its crystal structure. Based on extensive experience and research, the inventors of this application have discovered that, compared to SnO2, Sn3O4 exhibits a higher concentration of oxygen vacancies and carriers, resulting in superior gas-sensing performance without doping or composite processes. Furthermore, the orthorhombic Sn3O4 is a non-close-packed phase, with larger interstitial spaces and higher intergranular interface energies, which are more conducive to further doping modifications and gas adsorption during the gas-sensing response process. After loading Pd and Ga3O4, the orthorhombic Sn3O4 demonstrates a better specific response to propane compared to SnO2.

[0038] A first aspect of this application provides a composite gas-sensitive material, comprising:

[0039] The gas-sensitive layer comprises Pd-modified Sn3O4.

[0040] A modification layer is disposed on the surface of the gas-sensitive layer, and the modification layer comprises Ga2O3. "The modification layer is disposed on the surface of the gas-sensitive layer" means that the modification layer is disposed on one side of the gas-sensitive layer, rather than completely enclosing the gas-sensitive layer.

[0041] The composite gas-sensitive material provided in this application, compared to the traditional SnO2 gas-sensitive layer, exhibits a higher oxygen vacancy concentration and carrier concentration in Sn3O4, resulting in superior gas-sensing performance. Furthermore, the Sn3O4 crystal structure has larger interstitial spaces and higher intergranular interface energy, which is beneficial for gas adsorption during the gas-sensing response process. Moreover, under Pd loading conditions, the synergistic effect of Ga2O3 enhances the specificity of the response to propane. Therefore, the composite gas-sensitive material provided in this application combines high sensitivity, high selectivity, and a low detection limit.

[0042] In one example, the mass percentage of Pd in ​​the Pd-modified Sn3O4 is 2.5% to 4.5%. It is understood that the mass percentage of Pd can be selected from any value between 2.5% and 4.5%. Specifically, the mass percentage of Pd includes, but is not limited to, 2.5%, 2.8%, 3%, 3.2%, 3.3%, 3.4%, 3.5%, 3.6%, 4%, or 4.5%.

[0043] Preferably, the mass percentage of Pd in ​​the Pd-modified Sn3O4 is 3.3% to 3.7%. Adjusting the weight percentage of Pd and Sn3O4 is beneficial to improving the dispersion of Pd and increasing the compatibility between Pd and Sn3O4; at the same time, with the synergy of Ga2O3, the selectivity of the composite gas-sensitive material to propane is improved.

[0044] In one example, the thickness of the gas-sensitive layer is 1.5 μm to 2 μm. Specifically, the thickness of the gas-sensitive layer includes, but is not limited to, 1.5 μm, 1.7 μm, 1.8 μm, 1.9 μm, or 2 μm.

[0045] In one example, the thickness of the modification layer is 3nm to 7nm. Specifically, the thickness of the modification layer includes, but is not limited to, 3nm, 4nm, 4.5nm, 4.7nm, 4.8nm, 4.9nm, 5nm, 5.1nm, 5.2nm, 5.5nm, 6nm, 6.5nm, or 7nm.

[0046] By adjusting the thickness of the gas-sensitive layer and the modification layer, it is possible to ensure the sensitivity and response time of the gas-sensitive material while ensuring that the material is not affected by other elements in the environment and has high stability.

[0047] A second aspect of this application provides a method for preparing the composite gas-sensitive material described in any example of the first aspect of this application, comprising the following steps:

[0048] The gas-sensitive layer is prepared by spraying and drying a gas-sensitive slurry containing Pd-modified Sn3O4.

[0049] The modification layer is prepared by sputtering Ga2O3 onto the surface of the gas-sensitive layer using a metal mask.

[0050] In one example, the sputtering process parameters for the metal mask include a sputtering power of 100W to 140W. Preferably, the sputtering power is 110W to 130W, and more preferably, the sputtering power is 120W.

[0051] In one example, the process parameters for sputtering the metal mask include a sputtering time of 60s to 120s.

[0052] In one example, the preparation process of the gas-sensitive slurry containing the Pd-modified Sn3O4 includes:

[0053] Sn3O4 powder, Pd slurry and / or Pd powder are mixed in an alumina dispersion, and then ball milling is performed after mixing and drying to prepare Pd-modified Sn3O4 powder material.

[0054] The Pd-modified Sn3O4 powder material is mixed with an organic slurry to prepare a gas-sensitive slurry containing Pd-modified Sn3O4.

[0055] In one example, during the mixing of Sn3O4 powder and Pd slurry in a dispersion, the mass fraction of the Pd slurry is 2 wt% to 6 wt%. Preferably, the mass fraction of the Pd slurry is 4 wt% to 6 wt%.

[0056] In one example, a nano-alumina dispersion was used as the dispersion liquid. The nano-alumina particles had a diameter of 5 nm to 10 nm. The nano-alumina in the gas-sensitive layer acts as a dispersant, thereby inhibiting excessive growth of the gas-sensitive material particles and preventing Pd particle agglomeration from affecting the gas-sensitive response.

[0057] In one example, the solvent of the organic slurry, by mass percentage, comprises: 50%–70% terpineol, 20%–30% butyl carbitol acetate, and 5%–30% dibutyl phthalate; and the solute of the organic slurry, by mass percentage, comprises: 5%–7% ethyl cellulose, 3%–5% Span 85, 0.5%–1% 1,4-butyrolactone, and 0.5%–1% hydrogenated castor oil.

[0058] In one example, the preparation process of the Sn3O4 powder includes:

[0059] SnCl2 solution, oxidant and alkali solution are mixed and reacted at 160℃~200℃ for 10h~14h. After the reaction is completed, the mixture is cooled in a water bath at room temperature and filtered to prepare Sn3O4 powder.

[0060] In one example, the concentration of the SnCl2 solution is 0.8 mol / L to 1.2 mol / L.

[0061] In one example, the raw materials for preparing the SnCl2 solution include SnCl2·2H2O and deionized water.

[0062] In one example, the oxidant is sodium citrate.

[0063] In one specific example, the oxidant is sodium citrate dihydrate.

[0064] In one specific example, the alkali solution is a sodium hydroxide solution.

[0065] In one specific example, the molar ratio of SnCl2·2H2O, sodium citrate dihydrate, and sodium hydroxide is (1.5–2.5):(4.5–5.5):1. Controlling the molar ratio of SnCl2·2H2O, sodium citrate dihydrate, and sodium hydroxide makes it easier to control the reaction rate and improve the efficiency of Sn3O4 preparation.

[0066] More preferably, the molar ratio of SnCl2·2H2O, sodium citrate dihydrate, and sodium hydroxide is 2:5:1.

[0067] In one specific example, the preparation method of the gas-sensitive slurry containing Pd-modified Sn3O4 includes the following steps:

[0068] S10: Weigh out SnCl2·2H2O and dissolve it in deionized water. Stir for 20-40 minutes and sonicate for 8-12 minutes to ensure complete dissolution.

[0069] S20: Weigh out sodium citrate dihydrate and dissolve it in the solution of S10; add sodium hydroxide solution to make the molar ratio of SnCl2·2H2O, sodium citrate dihydrate and sodium hydroxide (1.5~2.5):(4.5~5.5):1, stir evenly and prepare the precursor solution;

[0070] S30. Transfer the precursor solution prepared in S20 to a 100 mL Teflon container, place it in a high-pressure reactor, and keep it at 160℃~200℃ for 10h~14h. Then cool it in a water bath at room temperature. Filter the cooled solution to obtain powder.

[0071] S40. The powder obtained in S30 is washed with alkaline solution and distilled water, and finally washed with acetone and dried at 50℃~70℃ to prepare Sn3O4 powder.

[0072] S50. Weigh the Sn3O4 powder prepared in S40, add 2wt% to 6wt% Pd slurry, and add alumina dispersion slurry; after the addition is complete, transfer it to a ball mill jar and ball mill at a speed of 300 r / min to 400 r / min for 3 h to 5 h; then suck the ball-milled suspension into a beaker and dry it in an oven at 50℃ to 70℃ to obtain the pretreated powder material;

[0073] S60. Take the pretreated powder material obtained in S50, add organic slurry to make the slurry viscosity 5000mPa·s~7500mPa·s; transfer the slurry to a ball mill jar and ball mill at a speed of 300r / min~400r / min for 3h~5h to prepare Pd modified Sn3O4 slurry.

[0074] A third aspect of this application provides a propane gas sensor, comprising a substrate and a composite gas-sensitive material as described in any example of the first aspect of this application, wherein the composite gas-sensitive material is laminated on the surface of the substrate through a gas-sensitive layer.

[0075] In one example, the substrate integrates a heater and interdigitated electrodes. The composite gas-sensitive material is laminated onto the interdigitated electrode region on the substrate surface via a gas-sensitive layer.

[0076] The following are specific examples. Unless otherwise specified, the raw materials used in the examples are all commercially available products.

[0077] Example 1

[0078] Example 1 of this application provides a method for preparing Pd / Ga2O3@Sn3O4 and a propane gas sensor, the specific steps of which are as follows:

[0079] (1) Preparation of Sn3O4: 0.9g SnCl2·2H2O was dissolved in 10mL deionized water, stirred for 30min, and sonicated for 10min until completely dissolved; after complete dissolution, 2.94g Na3C6H5O7·2H2O was weighed and added, along with 10mL 0.2M NaOH solution, and stirred evenly to obtain a precursor solution; the precursor solution was transferred to a 100mL Teflon container, placed in a high-pressure reactor, kept at 180℃ in an oven for 12h, and then rapidly cooled in room temperature water. After filtration and separation, powder was obtained. The powder was washed with 0.2M NaOH solution and distilled water, and finally washed with acetone. After being dried in an oven at 60℃ overnight, Sn3O4 powder material was prepared.

[0080] (2) Preparation of Pd-modified Sn3O4 powder material: Weigh the Sn3O4 powder material prepared in step (1), add Pd slurry (5wt.% aqueous solution) and nano-alumina aqueous dispersion (particle size 5nm~10nm, 20wt.% aqueous solution, Aladdin); transfer it to a ball mill jar, add anhydrous ethanol to cover the surface of the ball mill beads, and ball mill at 350r / min for 4h. Then, the ball-milled suspension is sucked out into a beaker and dried in an oven at 60℃ to obtain the pretreated Pd-modified Sn3O4 powder material, wherein the mass percentage of Pd in ​​the Pd-modified Sn3O4 powder material is 3.5%.

[0081] (3) Preparation of Pd-modified Sn3O4 slurry: The pretreated Pd-modified Sn3O4 powder material obtained in step (2) was placed in a mortar, and organic slurry was added while grinding until the slurry viscosity was 5000 mPa·s to 7500 mPa·s. Then, it was transferred to a ball mill jar and ball-milled at 350 r / min for 4 h to obtain Pd-modified Sn3O4 slurry. The solvent of the organic slurry, by mass percentage, included: 60% terpineol, 30% butyl carbitol acetate and 10% dibutyl phthalate. The solute of the organic slurry, by mass percentage, included: 6% ethyl cellulose, 4% Span 85, 1% 1,4-butyrolactone and 0.5% hydrogenated castor oil.

[0082] (4) Fabrication of the gas sensor: A substrate integrating a heater and interdigitated electrodes was selected. Pd-modified Sn3O4 slurry was sprayed onto the interdigitated electrode area of ​​the substrate using a needle with a 60-micron aperture. The substrate was placed in a constant temperature drying oven and dried at 80℃ for 20h. Then, it was sintered at 400℃ for 3h to remove the organic slurry and obtain a gas-sensitive layer with a thickness of 2μm. Then, Ga2O3 was sputtered using a metal mask at a power of 120W and a sputtering time of 90s to obtain a 5nm modified layer. Finally, a propane gas sensor was prepared.

[0083] Example 2

[0084] Example 2 of this application provides a method for preparing Pd / Ga2O3@Sn3O4 and a propane gas sensor, the specific steps of which are as follows:

[0085] (1) Preparation of Sn3O4: 0.9g SnCl2·2H2O was dissolved in 10mL deionized water, stirred for 30min, and sonicated for 10min until completely dissolved; after complete dissolution, 2.94g Na3C6H5O7·2H2O was weighed and added, along with 10mL 0.2M NaOH solution, and stirred evenly to obtain a precursor solution; the precursor solution was transferred to a 100mL Teflon container, placed in a high-pressure reactor, kept at 180℃ in an oven for 12h, and then rapidly cooled in room temperature water. After filtration and separation, powder was obtained. The powder was washed with 0.2M NaOH solution and distilled water, and finally washed with acetone. After being dried in an oven at 60℃ overnight, Sn3O4 powder material was prepared.

[0086] (2) Preparation of Pd-modified Sn3O4 powder material: Weigh the Sn3O4 powder material prepared in step (1), add Pd slurry (6wt.% aqueous solution) and nano-alumina aqueous dispersion (particle size 5nm~10nm, 20wt.% aqueous solution, Aladdin); transfer it to a ball mill jar, add anhydrous ethanol to cover the surface of the ball mill beads, and ball mill at 350r / min for 4h. Then, the ball-milled suspension is sucked out into a beaker and dried in an oven at 60℃ to obtain the pretreated Pd-modified Sn3O4 powder material, wherein the mass percentage of Pd in ​​the Pd-modified Sn3O4 powder material is 4%.

[0087] (3) Preparation of Pd-modified Sn3O4 slurry: The pretreated Pd-modified Sn3O4 powder material obtained in step (2) was placed in a mortar, and organic slurry was added while grinding until the slurry viscosity was 5000 mPa·s to 7500 mPa·s. Then, it was transferred to a ball mill jar and ball-milled at 350 r / min for 4 h to obtain Pd-modified Sn3O4 slurry. The solvent of the organic slurry, by mass percentage, included: 60% terpineol, 30% butyl carbitol acetate and 10% dibutyl phthalate. The solute of the organic slurry, by mass percentage, included: 6% ethyl cellulose, 4% Span 85, 1% 1,4-butyrolactone and 0.5% hydrogenated castor oil.

[0088] (4) Fabrication of the gas sensor: A substrate integrating a heater and interdigitated electrodes was selected. Pd-modified Sn3O4 slurry was sprayed onto the interdigitated electrode area of ​​the substrate using a needle with a 60-micron aperture. The substrate was placed in a constant temperature drying oven and dried at 80℃ for 20h. Then, it was sintered at 400℃ for 3h to remove the organic slurry and obtain a gas-sensitive layer with a thickness of 2μm. Then, Ga2O3 was sputtered using a metal mask at a power of 120W and a sputtering time of 90s to obtain a 5nm modified layer. Finally, a propane gas sensor was prepared.

[0089] Example 3

[0090] Example 3 of this application provides a method for preparing Pd / Ga2O3@Sn3O4 and a propane gas sensor, the specific steps of which are as follows:

[0091] (1) Preparation of Sn3O4: 0.9g SnCl2·2H2O was dissolved in 10mL deionized water, stirred for 30min, and sonicated for 10min until completely dissolved; after complete dissolution, 2.94g Na3C6H5O7·2H2O was weighed and added, along with 10mL 0.2M NaOH solution, and stirred evenly to obtain a precursor solution; the precursor solution was transferred to a 100mL Teflon container, placed in a high-pressure reactor, kept at 180℃ in an oven for 12h, and then rapidly cooled in room temperature water. After filtration and separation, powder was obtained. The powder was washed with 0.2M NaOH solution and distilled water, and finally washed with acetone. After being dried in an oven at 60℃ overnight, Sn3O4 powder material was prepared.

[0092] (2) Preparation of Pd-modified Sn3O4 powder material: Weigh the Sn3O4 powder material prepared in step (1), add Pd slurry (3.4 wt.% aqueous solution) and nano-alumina aqueous dispersion (particle size 5 nm to 10 nm, 20 wt.% aqueous solution, Aladdin); transfer it to a ball mill jar, add anhydrous ethanol to cover the surface of the ball mill beads, and ball mill at 350 r / min for 4 h. Then, the ball-milled suspension is sucked out into a beaker and dried in an oven at 60 °C to obtain the pretreated Pd-modified Sn3O4 powder material, wherein the mass percentage of Pd in ​​the Pd-modified Sn3O4 powder material is 3%.

[0093] (3) Preparation of Pd-modified Sn3O4 slurry: The pretreated Pd-modified Sn3O4 powder material obtained in step (2) was placed in a mortar, and organic slurry was added while grinding until the slurry viscosity was 5000 mPa·s to 7500 mPa·s. Then, it was transferred to a ball mill jar and ball-milled at 350 r / min for 4 h to obtain Pd-modified Sn3O4 slurry. The solvent of the organic slurry, by mass percentage, included: 60% terpineol, 30% butyl carbitol acetate and 10% dibutyl phthalate. The solute of the organic slurry, by mass percentage, included: 6% ethyl cellulose, 4% Span 85, 1% 1,4-butyrolactone and 0.5% hydrogenated castor oil.

[0094] (4) Fabrication of the gas sensor: A substrate integrating a heater and interdigitated electrodes was selected. Pd-modified Sn3O4 slurry was sprayed onto the interdigitated electrode area of ​​the substrate using a needle with a 60-micron aperture. The substrate was placed in a constant temperature drying oven and dried at 80℃ for 20h. Then, it was sintered at 400℃ for 3h to remove the organic slurry and obtain a gas-sensitive layer with a thickness of 2μm. Then, Ga2O3 was sputtered using a metal mask at a power of 120W and a sputtering time of 90s to obtain a 5nm modified layer. Finally, a propane gas sensor was prepared.

[0095] Example 4

[0096] Example 4 of this application provides a method for preparing Pd / Ga2O3@Sn3O4 and a propane gas sensor, the specific steps of which are as follows:

[0097] (1) Preparation of Sn3O4: 0.9g SnCl2·2H2O was dissolved in 10mL deionized water, stirred for 30min, and sonicated for 10min until completely dissolved; after complete dissolution, 2.94g Na3C6H5O7·2H2O was weighed and added, along with 10mL 0.2M NaOH solution, and stirred evenly to obtain a precursor solution; the precursor solution was transferred to a 100mL Teflon container, placed in a high-pressure reactor, kept at 180℃ in an oven for 12h, and then rapidly cooled in room temperature water. After filtration and separation, powder was obtained. The powder was washed with 0.2M NaOH solution and distilled water, and finally washed with acetone. After being dried in an oven at 60℃ overnight, Sn3O4 powder material was prepared.

[0098] (2) Preparation of Pd-modified Sn3O4 powder material: Weigh the Sn3O4 powder material prepared in step (1), add Pd slurry (5wt.% aqueous solution) and nano-alumina aqueous dispersion (particle size 5nm~10nm, 20wt.% aqueous solution, Aladdin); transfer it to a ball mill jar, add anhydrous ethanol to cover the surface of the ball mill beads, and ball mill at 350r / min for 4h. Then, the ball-milled suspension is sucked out into a beaker and dried in an oven at 60℃ to obtain the pretreated Pd-modified Sn3O4 powder material, wherein the mass percentage of Pd in ​​the Pd-modified Sn3O4 powder material is 3.5%.

[0099] (3) Preparation of Pd-modified Sn3O4 slurry: The pretreated Pd-modified Sn3O4 powder material obtained in step (2) was placed in a mortar, and organic slurry was added while grinding until the slurry viscosity was 5000 mPa·s to 7500 mPa·s. Then, it was transferred to a ball mill jar and ball-milled at 350 r / min for 4 h to obtain Pd-modified Sn3O4 slurry. The solvent of the organic slurry, by mass percentage, included: 60% terpineol, 30% butyl carbitol acetate and 10% dibutyl phthalate. The solute of the organic slurry, by mass percentage, included: 6% ethyl cellulose, 4% Span 85, 1% 1,4-butyrolactone and 0.5% hydrogenated castor oil.

[0100] (4) Fabrication of the gas sensor: A substrate integrating a heater and interdigitated electrodes was selected. Pd-modified Sn3O4 slurry was sprayed onto the interdigitated electrode area of ​​the substrate using a needle with a 60-micron aperture. The substrate was placed in a constant temperature drying oven and dried at 80℃ for 20h. Then, it was sintered at 400℃ for 3h to remove the organic slurry and obtain a gas-sensitive layer with a thickness of 1.5μm. Then, Ga2O3 was sputtered using a metal mask at a power of 120W and a sputtering time of 90s to obtain a 5nm modified layer. Finally, a propane gas sensor was prepared.

[0101] Example 5

[0102] Example 5 of this application provides a method for preparing Pd / Ga2O3@Sn3O4 and a propane gas sensor, the specific steps of which are as follows:

[0103] (1) Preparation of Sn3O4: 0.9g SnCl2·2H2O was dissolved in 10mL deionized water, stirred for 30min, and sonicated for 10min until completely dissolved; after complete dissolution, 2.94g Na3C6H5O7·2H2O was weighed and added, along with 10mL 0.2M NaOH solution, and stirred evenly to obtain a precursor solution; the precursor solution was transferred to a 100mL Teflon container, placed in a high-pressure reactor, kept at 180℃ in an oven for 12h, and then rapidly cooled in room temperature water. After filtration and separation, powder was obtained. The powder was washed with 0.2M NaOH solution and distilled water, and finally washed with acetone. After being dried in an oven at 60℃ overnight, Sn3O4 powder material was prepared.

[0104] (2) Preparation of Pd-modified Sn3O4 powder material: Weigh the Sn3O4 powder material prepared in step (1), add Pd slurry (5wt.% aqueous solution) and nano-alumina aqueous dispersion (particle size 5nm~10nm, 20wt.% aqueous solution, Aladdin); transfer it to a ball mill jar, add anhydrous ethanol to cover the surface of the ball mill beads, and ball mill at 350r / min for 4h. Then, the ball-milled suspension is sucked out into a beaker and dried in an oven at 60℃ to obtain the pretreated Pd-modified Sn3O4 powder material, wherein the mass percentage of Pd in ​​the Pd-modified Sn3O4 powder material is 3.5%.

[0105] (3) Preparation of Pd-modified Sn3O4 slurry: The pretreated Pd-modified Sn3O4 powder material obtained in step (2) was placed in a mortar, and organic slurry was added while grinding until the slurry viscosity was 5000 mPa·s to 7500 mPa·s. Then, it was transferred to a ball mill jar and ball-milled at 350 r / min for 4 h to obtain Pd-modified Sn3O4 slurry. The solvent of the organic slurry, by mass percentage, included: 60% terpineol, 30% butyl carbitol acetate and 10% dibutyl phthalate. The solute of the organic slurry, by mass percentage, included: 6% ethyl cellulose, 4% Span 85, 1% 1,4-butyrolactone and 0.5% hydrogenated castor oil.

[0106] (4) Fabrication of the gas sensor: A substrate integrating a heater and interdigitated electrodes was selected. Pd-modified Sn3O4 slurry was sprayed onto the interdigitated electrode area of ​​the substrate using a needle with a 60-micron aperture. The substrate was placed in a constant temperature drying oven and dried at 80℃ for 20h. Then, it was sintered at 400℃ for 3h to remove the organic slurry and obtain a gas-sensitive layer with a thickness of 1.7μm. Then, Ga2O3 was sputtered using a metal mask at a power of 120W for 90s to obtain a 5nm modified layer. Finally, a propane gas sensor was prepared.

[0107] Comparative Example 1

[0108] Comparative Example 1 is basically the same as Example 1, the main difference being that Comparative Example 1 contains only Sn3O4. The specific preparation process is as follows:

[0109] (1) Preparation of Sn3O4: 0.9g SnCl2·2H2O was dissolved in 10mL deionized water, stirred for 30min, and sonicated for 10min until completely dissolved; after complete dissolution, 2.94g Na3C6H5O7·2H2O was weighed and added, along with 10mL 0.2M NaOH solution, and stirred evenly to obtain a precursor solution; the precursor solution was transferred to a 100mL Teflon container, placed in a high-pressure reactor, kept at 180℃ in an oven for 12h, and then rapidly cooled in room temperature water. After filtration and separation, powder was obtained. The powder was washed with 0.2M NaOH solution and distilled water, and finally washed with acetone. After being dried in an oven at 60℃ overnight, Sn3O4 powder material was prepared.

[0110] (2) Preparation of Sn3O4 slurry: The Sn3O4 powder material obtained in step (1) was placed in a mortar and ground with organic slurry while adding the powder until the slurry viscosity was 5000 mPa·s to 7500 mPa·s. Then, it was transferred to a ball mill jar and ball-milled at 350 r / min for 4 h to obtain Sn3O4 slurry. The solvent of the organic slurry, by mass percentage, included: 60% terpineol, 30% butyl carbitol acetate and 10% dibutyl phthalate. The solute of the organic slurry, by mass percentage, included: 6% ethyl cellulose, 4% Span 85, 1% 1,4-butyrolactone and 0.5% hydrogenated castor oil.

[0111] (3) Preparation of propane gas sensor: Select a substrate with integrated heater and interdigitated electrodes, use a needle with a 60-micron aperture to spray Sn3O4 slurry onto the interdigitated electrode area of ​​the substrate, place it in a constant temperature drying oven at 80℃ for 20h, and then sinter at 400℃ for 3h to remove organic slurry to obtain a gas-sensitive layer with a thickness of 2μm; finally prepare the gas sensor.

[0112] Comparative Example 2

[0113] Comparative Example 2 is basically the same as Example 1, the main difference being that Comparative Example 2 only contains Pd-modified Sn3O4. The specific preparation process is as follows:

[0114] (1) Preparation of Sn3O4: 0.9g SnCl2·2H2O was dissolved in 10mL deionized water, stirred for 30min, and sonicated for 10min until completely dissolved; after complete dissolution, 2.94g Na3C6H5O7·2H2O was weighed and added, along with 10mL 0.2M NaOH solution, and stirred evenly to obtain a precursor solution; the precursor solution was transferred to a 100mL Teflon container, placed in a high-pressure reactor, kept at 180℃ in an oven for 12h, and then rapidly cooled in room temperature water. After filtration and separation, powder was obtained. The powder was washed with 0.2M NaOH solution and distilled water, and finally washed with acetone. After being dried in an oven at 60℃ overnight, Sn3O4 powder material was prepared.

[0115] (2) Preparation of Pd-modified Sn3O4 powder material: Weigh the Sn3O4 powder material prepared in step (1), add Pd slurry (5wt.% aqueous solution) and nano-alumina aqueous dispersion (particle size 5nm~10nm, 20wt.% aqueous solution, Aladdin); transfer it to a ball mill jar, add anhydrous ethanol to cover the surface of the ball mill beads, and ball mill at 350r / min for 4h. Then, the ball-milled suspension is sucked out into a beaker and dried in an oven at 60℃ to obtain the pretreated Pd-modified Sn3O4 powder material, wherein the mass percentage of Pd in ​​the Pd-modified Sn3O4 powder material is 3.5%.

[0116] (3) Preparation of Pd-modified Sn3O4 slurry: The pretreated Pd-modified Sn3O4 powder material obtained in step (2) was placed in a mortar, and organic slurry was added while grinding until the slurry viscosity was 5000 mPa·s to 7500 mPa·s. Then, it was transferred to a ball mill jar and ball-milled at 350 r / min for 4 h to obtain Pd-modified Sn3O4 slurry. The solvent of the organic slurry, by mass percentage, included: 60% terpineol, 30% butyl carbitol acetate and 10% dibutyl phthalate. The solute of the organic slurry, by mass percentage, included: 6% ethyl cellulose, 4% Span 85, 1% 1,4-butyrolactone and 0.5% hydrogenated castor oil.

[0117] (4) Fabrication of gas sensor: Select a substrate with integrated heater and interdigitated electrodes, use a needle with a 60-micron aperture to spray Pd modified Sn3O4 slurry onto the interdigitated electrode area of ​​the substrate, place it in a constant temperature drying oven at 80℃ for 20h, and then sinter at 400℃ for 3h to remove organic slurry to obtain a gas-sensitive layer with a thickness of 2μm; fabricate gas sensor.

[0118] Comparative Example 3

[0119] Comparative Example 3 is basically the same as Example 1, with the main difference being that Comparative Example 3 contains only Sn3O4 and Ga2O3. The specific preparation process is as follows:

[0120] (1) Preparation of Sn3O4: 0.9g SnCl2·2H2O was dissolved in 10mL deionized water, stirred for 30min, and sonicated for 10min until completely dissolved; after complete dissolution, 2.94g Na3C6H5O7·2H2O was weighed and added, along with 10mL 0.2M NaOH solution, and stirred evenly to obtain a precursor solution; the precursor solution was transferred to a 100mL Teflon container, placed in a high-pressure reactor, kept at 180℃ in an oven for 12h, and then rapidly cooled in room temperature water. After filtration and separation, powder was obtained. The powder was washed with 0.2M NaOH solution and distilled water, and finally washed with acetone. After being dried in an oven at 60℃ overnight, Sn3O4 powder material was prepared.

[0121] (2) Preparation of Sn3O4 slurry: The Sn3O4 powder material obtained in step (1) was placed in a mortar and ground with organic slurry while adding the powder until the slurry viscosity was 5000 mPa·s to 7500 mPa·s. Then, it was transferred to a ball mill jar and ball-milled at 350 r / min for 4 h to obtain Sn3O4 slurry. The solvent of the organic slurry, by mass percentage, included: 60% terpineol, 30% butyl carbitol acetate and 10% dibutyl phthalate. The solute of the organic slurry, by mass percentage, included: 6% ethyl cellulose, 4% Span 85, 1% 1,4-butyrolactone and 0.5% hydrogenated castor oil.

[0122] (3) Fabrication of the gas sensor: A substrate integrating a heater and interdigitated electrodes was selected. Sn3O4 slurry was sprayed onto the interdigitated electrode area of ​​the substrate using a needle with a 60-micron aperture. The substrate was placed in a constant temperature drying oven and dried at 80℃ for 20h. Then, it was sintered at 400℃ for 3h to remove the organic slurry and obtain a gas-sensitive layer with a thickness of 2μm. Then, Ga2O3 was sputtered using a metal mask at a power of 120W and a sputtering time of 90s to obtain a modification layer with a thickness of 10nm. Finally, the gas sensor was obtained.

[0123] Comparative Example 4

[0124] Comparative Example 4 is basically the same as Example 1, the main difference being that Comparative Example 4 contains only SnO2. The specific steps are as follows:

[0125] (1) Preparation of SnO2: 10 mmol of tin chloride was dissolved in 50 ml of benzyl alcohol and stirred until a colorless and transparent solution was obtained. The solution was kept at 200 °C for 48 h. After the incubation period, the upper yellow clear liquid was discarded, and the brownish-yellow powder at the bottom was retained. 30 ml of ethanol was added, followed by 40 ml of dichloromethane. The mixture was then transferred to a centrifuge tube and centrifuged. After centrifugation, the supernatant was discarded, and the mixture was washed and centrifuged repeatedly until the supernatant was colorless. The precipitate was dried to obtain SnO2 powder.

[0126] (2) Preparation of SnO2 slurry: The SnO2 powder material obtained in step (1) was placed in a mortar and ground with organic slurry while adding the powder until the slurry viscosity was 5000 mPa·s to 7500 mPa·s. Then, it was transferred to a ball mill jar and ball-milled at 350 r / min for 4 h to obtain SnO2 slurry. The solvent of the organic slurry, by mass percentage, included: 60% terpineol, 30% butyl carbitol acetate and 10% dibutyl phthalate. The solute of the organic slurry, by mass percentage, included: 6% ethyl cellulose, 4% Span 85, 1% 1,4-butyrolactone and 0.5% hydrogenated castor oil.

[0127] (3) Fabrication of gas sensor: Select a substrate with integrated heater and interdigitated electrodes, use a needle with a 60-micron aperture to spray SnO2 slurry onto the interdigitated electrode area of ​​the substrate, place it in a constant temperature drying oven at 80℃ for 20h, and then sinter at 400℃ for 3h to remove organic slurry to obtain a gas-sensitive layer with a thickness of 2μm; thus obtaining a gas sensor.

[0128] The gas sensors prepared in the examples and comparative examples were tested.

[0129] Gas-sensitive response performance testing is performed using a gas-sensitive performance testing platform. The platform typically consists of a gas path control module, a signal acquisition module, and a PC. By controlling the flow controller parameters corresponding to the background gas and the test gas in the gas path control module, different concentrations of test gas can be obtained. During testing, the prepared gas sensor is placed in a sealed space with interconnected gas paths and good airtightness, and the gas sensor is connected to the signal acquisition module for testing.

[0130] After stabilizing the resistance value of the gas sensor at the test temperatures (50℃, 100℃, 150℃, 200℃, 250℃, and 300℃), 500 ppm of propane, formaldehyde, acetone, hydrogen, and carbon monoxide gases were introduced respectively, and the resistance values ​​of the gas sensor were recorded. The resistance value of the gas sensor before the gas to be tested is recorded as Ra, and the resistance value under the test atmosphere is recorded as Rg. The response intensity of the gas sensor to different gases was calculated as S = Ra / Rg.

[0131] See Figure 1 The propane gas sensor prepared in Example 1 has a responsivity of 0.8 for 150 ppm propane at 200°C. When the propane concentration is 300 ppm, the responsivity is >2. Further increasing the propane concentration, the responsivity of the propane gas sensor prepared in Example 1 increases. At 450 ppm, the responsivity is initially around 5, and at 1200 ppm, the responsivity reaches 7. This indicates that the propane gas sensor prepared in Example 1 has a low detection limit for propane, reaching the ppm level.

[0132] See Figure 2 The gas sensors prepared in Example 1 and Comparative Examples 1-4 of this application exhibit response strength to 500 ppm propane gas at different operating temperatures. It can be seen that the gas sensor prepared in Example 1 has a slightly lower response than Comparative Example 2 at an operating temperature of 50°C, but at operating temperatures of 100°C and above, the responsivity of the gas sensor in Example 1 is higher than that of the comparative examples.

[0133] See Figure 3 The gas sensor prepared in Example 1 of this application exhibits response strengths at 200°C to 500 ppm of propane, formaldehyde, acetone, H2, and CO. The gas sensor prepared in Example 1 shows response strengths of approximately 1 for formaldehyde, acetone, H2, and CO, but its response strength to propane is 6, indicating that the gas sensor provided in this application has good selectivity for propane.

[0134] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0135] The embodiments described above are merely illustrative of several implementation methods of this application, intended to facilitate a detailed understanding of the technical solutions of this application, but should not be construed as limiting the scope of protection of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the scope of protection of this application. It should be understood that technical solutions obtained by those skilled in the art based on the technical solutions provided in this application through logical analysis, reasoning, or limited experimentation are all within the scope of protection of the appended claims. Therefore, the scope of protection of this patent application should be determined by the content of the appended claims, and the specification can be used to interpret the content of the claims.

Claims

1. A composite gas-sensitive material, characterized in that, The composite gas-sensitive material is a propane gas-sensitive material, and the composite gas-sensitive material comprises: A gas-sensitive layer comprising Pd-modified Sn3O4, wherein the mass percentage of Pd in ​​the Pd-modified Sn3O4 is 2.5% to 4.5%; A modification layer is disposed on the surface of the gas-sensitive layer, and the modification layer includes Ga2O3; the modification layer is formed by sputtering Ga2O3 onto the surface of the gas-sensitive layer using a metal mask; the thickness of the modification layer is 3nm~7nm.

2. The composite gas-sensitive material according to claim 1, characterized in that, In the Pd-modified Sn3O4, the mass percentage of Pd is 3.3% to 3.7%.

3. The composite gas-sensitive material according to claim 1 or 2, characterized in that, The thickness of the gas-sensitive layer is 1.5μm~2μm.

4. A method for preparing the composite gas-sensitive material according to any one of claims 1 to 3, characterized in that, The composite gas-sensitive material is a propane gas-sensitive material, and the process includes the following steps: The gas-sensitive layer is prepared by spraying and drying the gas-sensitive slurry containing the Pd-modified Sn3O4. The modification layer is prepared by sputtering Ga2O3 onto the surface of the gas-sensitive layer using a metal mask; the thickness of the modification layer is 3 nm to 7 nm.

5. The method for preparing the composite gas-sensitive material according to claim 4, characterized in that, The process parameters for sputtering the metal mask include: sputtering power of 100W~140W.

6. The method for preparing the composite gas-sensitive material according to claim 4, characterized in that, The preparation process of the gas-sensitive slurry containing Pd-modified Sn3O4 includes: Sn3O4 powder, Pd slurry and / or Pd powder are mixed in a dispersion, and then ball milling media are added for ball milling. After drying, Pd-modified Sn3O4 powder material is prepared. The Pd-modified Sn3O4 powder material is mixed with an organic slurry to prepare a gas-sensitive slurry containing Pd-modified Sn3O4.

7. The method for preparing the composite gas-sensitive material according to claim 6, characterized in that, The preparation process of the Sn3O4 powder includes: SnCl2 solution, oxidant and alkaline solution are mixed and reacted at 160℃~200℃ for 10h~14h. After the reaction is completed, the mixture is cooled in a water bath at room temperature and filtered to prepare Sn3O4 powder.

8. The method for preparing the composite gas-sensitive material according to claim 6 or 7, characterized in that, The solvent of the organic slurry, by mass percentage, comprises: 50%~70% terpineol, 20%~30% butyl carbitol acetate, and 5%~30% dibutyl phthalate; relative to the solvent of the organic slurry, the solute of the organic slurry, by mass percentage, comprises: 5%~7% ethyl cellulose, 3%~5% Span 85, 0.5%~1% 1,4-butyrolactone, and 0.5%~1% hydrogenated castor oil.

9. A propane gas sensor, characterized in that, It includes a substrate and the composite gas-sensitive material according to any one of claims 1 to 3, wherein the composite gas-sensitive material is laminated on the surface of the substrate through the gas-sensitive layer.

Images