Low-temperature gas-sensitive material with In2O3 layer grown on ZnSnO3 surface and preparation method thereof

Abstract

The application relates to a low-temperature gas-sensitive material with an In2O3 layer grown on a ZnSnO3 surface and a preparation method thereof. The ZnSnO3 is an Archimedean solid particle, each triangular face around a multi-dimensional surface of the Archimedean solid particle is surrounded by three quadrilateral faces, each quadrilateral face shares a side with the triangular face, and In2O3 nanoparticles are uniformly grown on the multi-dimensional surface of the ZnSnO3 Archimedean solid particle to form a uniformly-distributed In2O3 particle composite layer. The method is as follows: zinc oxalate is dissolved in deionized water, tin chloride is added, sodium hydroxide particles are added, an indium nitrate solution is dropped, centrifugation is carried out after hydrothermal reaction, washing and drying are carried out, and finally calcination is carried out. The ZnSnO3 / In2O3 composite material has higher base resistance in air, high sensitivity to ethylene glycol gas and triethylamine gas, and low working temperature. The application has low preparation cost and good industrial application prospect.

Description

Technical Field

[0001] This invention belongs to the field of metal oxide semiconductor nanomaterials technology, and relates to a low-temperature gas-sensitive material with an In2O3 layer grown on the surface of ZnSnO3 and its preparation method. Background Technology

[0002] The continuous development of industry has facilitated people's daily lives, but it has also brought increasingly serious environmental pollution, such as substandard industrial waste gas treatment and excessive emissions of toxic and harmful gases, which have adversely affected people's health and living environment. In addition, emissions from vehicles such as automobiles and ships, harmful gases produced by fuel combustion, and volatile organic compounds also endanger human health. With the increasing environmental awareness of citizens, the requirements for the detection of toxic, harmful, flammable, and explosive gases are becoming increasingly stringent. Therefore, the research and development of ZnSnO3 gas sensors with high sensitivity to harmful gases, low optimal operating temperature, and good stability and selectivity has become one of the current research hotspots.

[0003] As can be seen from the adsorption-desorption detection mechanism of gas sensors, the gas-sensing performance of ZnSnO3 materials is closely related to its structure, specific surface area, pore number, and size distribution. To address the high operating temperature of ZnSnO3 gas-sensing materials, current research mainly focuses on improving their gas-sensing performance through microstructure manipulation, doping, loading with noble metals, and composite modification. Numerous experimental studies have shown that composite modification can significantly enhance the gas-sensing performance of ZnSnO3. Common types of composite sensing materials include: composites of metal oxides and carbon materials (carbon nanotubes, sheet graphene, etc.), composites of metal oxides and noble metals (noble metals such as Pb and Pt loaded on a metal substrate), composites of metal oxides and conductive polymers (polyaniline, polyethylene, etc.), and composites between different metal oxides (e.g., composites with NiO, ZnO, etc.). When two different materials are composited, a heterojunction forms at the interface between them, accompanied by electron transfer and the formation of a depletion layer, until the Fermi levels of the two materials reach equilibrium. The reconstructed Fermi level can influence the amount of surface gas adsorption by adjusting the surface barrier, which greatly improves the sensitivity, selectivity, and stability of the gas-sensitive material and reduces the operating temperature. It should be noted that existing composite modification materials for ZnSnO3 focus on nanostructured carbon materials, noble metals, and p-type metal oxides, while research reports on ZnSnO3 composites with low-cost n-type In2O3 are extremely rare.

[0004] Furthermore, ZnSnO3, as a typical perovskite-structured ternary metal oxide, is usually reported to have a rhombohedral phase, which is mostly hexahedral, with a small specific surface area and underdeveloped porosity. The crystal structure of rhombohedral ZnSnO3 is characterized by a=b=c, α=β=γ≠90°. Generally, the surface energies of the crystal faces of rhombohedral ZnSnO3 are (110)>(100)>(111), and the stable crystal structure often has the minimum surface energy. Therefore, the stable face of ZnSnO3 is (111). The (110) and (100) crystal faces with higher surface energies will gradually disappear during crystal growth, forming a stable structure. However, only the exposure of high surface energy active surfaces can provide more active sites for gas-sensitive chemical reactions, thereby improving the gas-sensitive performance of the material. Therefore, it is necessary to explore ZnSnO3 preparation methods that can expose multiple highly active surfaces and multi-directional crystal facet control technology to improve the sensitivity of gas-sensitive elements while reducing the operating temperature and extending the service life.

[0005] To date, no studies have been reported on the preparation of composite materials formed by growing In2O3 nanoparticles on an Archimedean ZnSnO3 substrate with multidimensional surfaces using a one-step hydrothermal method. Furthermore, few studies have achieved low-temperature detection of two different gases on the same metal-oxide-semiconductor sensor. Therefore, it is necessary to develop a method for preparing ZnSnO3 / In2O3 composite materials based on highly exposed multidirectional active ZnSnO3 materials, combining the advantages of n-type In2O3, in order to control the detection temperature of ethylene glycol-based target gases at around 100℃ and triethylamine-based target gases at around 180℃, while enhancing response sensitivity. Summary of the Invention

[0006] Purpose of the invention

[0007] To address the problems of poor exposure of high-surface-energy active surfaces, small specific surface area, and underdeveloped porosity in existing ZnSnO3 material preparation technologies, as well as the limitations of high detection temperatures (typically above 200℃), expensive composite modified materials, complex composite techniques, and the prevalence of composites with p-type metal oxide semiconductors, this invention provides a low-temperature gas-sensitive material with an In2O3 layer grown on the surface of ZnSnO3 and its preparation method. A simple one-step hydrothermal method yields a low-temperature gas-sensitive composite material with an In2O3 layer grown on the surface of Archimedean ZnSnO3, effectively simplifying the composite process, reducing the operating temperature of dual-gas detection, and significantly improving the sensitivity of ZnSnO3.

[0008] Technical solution

[0009] A low-temperature gas-sensitive material with an In2O3 layer grown on the surface of ZnSnO3. ZnSnO3 is an Archimedean particle with a particle size ranging from 500 to 900 nm. In the multidimensional surface of the Archimedean, each triangular face is surrounded by three quadrilateral faces, and each quadrilateral face shares an edge with the triangular face. The side length of each side ranges from 300 to 700 nm. In2O3 particles with a particle size ranging from 5 to 50 nm are grown on the multidimensional surface of the ZnSnO3 Archimedean particles to form a uniformly distributed In2O3 particle composite layer.

[0010] Furthermore, the powder particle size of the low-temperature gas-sensitive material with an In2O3 layer grown on the ZnSnO3 surface is 0.7-1.5 μm. The In2O3 nanoparticle layer grows layer by layer along the multidimensional surface, with a thickness ranging from 200-600 nm, forming a ZnSnO3 / In2O3 composite structure with nanoparticle layers coating the multidimensional surface. When the In2O3 nanoparticle layer thickness is greater than or equal to 200 nm and less than 400 nm, the In2O3 particles grow along the multidimensional surface of the ZnSnO3 Archimedean body while maintaining the Archimedean morphology. When the In2O3 nanoparticle layer thickness is greater than or equal to 400 nm and less than or equal to 600 nm, a ZnSnO3 / In2O3 low-temperature gas-sensitive composite material is formed with an Archimedean body substrate and a spheroidized In2O3 outer shell. The specific surface area of ​​the ZnSnO3 / In2O3 composite material reaches 42-65 m². 2 / g, containing micropores of 0.8-1.8nm and mesopores of 2.2-40nm.

[0011] A method for preparing a low-temperature gas-sensitive material with an In2O3 layer grown on the surface of ZnSnO3 as described above, comprising the following steps:

[0012] Step 1: Dissolve zinc oxalate in deionized water at room temperature and stir to make its concentration 2.625-3.325 g / 100 mL. Add tin chloride during stirring. The molar ratio of zinc oxalate to tin chloride is 1:(1-1.1). ZnSn(OH)6 primary particles precipitate out. After stirring and sieving, solution A is obtained.

[0013] Step 2: Add sodium hydroxide particles with a particle size of 16-20 mesh to solution A obtained in Step 1. The molar ratio of zinc oxalate to sodium hydroxide is 1:(9-12). Let stand for 10-20 minutes to precipitate secondary ZnSn(OH)6 particles. Introduce primary ZnSn(OH)6 particles and then continue stirring for 10-20 minutes to obtain suspension B containing Archimedes-shaped ZnSn(OH)6 precursor particles.

[0014] Step 3: Dissolve indium nitrate in deionized water to obtain an indium nitrate aqueous solution with a concentration of 0.1203-0.9024 g / 100 mL. The molar ratio of zinc oxalate to indium nitrate is 1:(0.02-0.15). At room temperature, slowly add the indium nitrate aqueous solution dropwise to the suspension B obtained in Step 2 at a rate of 0.08-0.2 mL / s. Stir continuously at 700-1200 rpm for 0.5-1 h to obtain a white suspension C. Transfer the white suspension C to a reaction vessel with a filling volume ratio of (1.75-1.9):5. Perform a hydrothermal reaction at a temperature of 80-120℃ and a pressure of 35-40 MPa for 8-12 h. Allow it to cool naturally to room temperature to obtain a milky white suspension D.

[0015] Step 4: Transfer the milky white suspension D obtained in Step 3 to a centrifuge and centrifuge at 3000-4500 rpm. Wash the white solid obtained by centrifugation with deionized water and ethanol alternately 3-5 times, and then place it in an oven at 60-75℃ and dry it in air for 10-18 hours. Place the dried powder in a muffle furnace and calcine it in air for 100-140 minutes. Start heating from room temperature at a rate of 2-5℃ / min and calcine at a temperature of 400-550℃ to finally obtain a low-temperature gas-sensitive material with an In2O3 layer grown on the surface of ZnSnO3. Furthermore, steps one and two are completed in a double-layer stirring device, which includes an outer cylinder and an inner cylinder. The inner cylinder is located inside the outer cylinder, and a filter stirring assembly is provided between the inner and outer cylinders. The filter stirring assembly is fixed to the outside of the inner cylinder. A fixed sleeve is provided inside the inner cylinder, and the bottom of the fixed sleeve is fixedly connected to the bottom of the outer cylinder. A stirring paddle is fitted on the outside of the fixed sleeve. A lifting mechanism is fixedly provided inside the fixed sleeve. The telescopic end of the lifting mechanism is rotatably connected to the top of the inner cylinder. A connecting sleeve is fixedly connected to the top of the telescopic end of the lifting mechanism. A rotating cover is fitted on the outside of the connecting sleeve. The rotating cover is rotatably connected to the connecting sleeve, and the edge of the rotating cover is fixedly connected to the inner cylinder.

[0016] It also includes a first drive assembly and a second drive assembly. The second drive assembly is located at the top of the outer side of the fixed sleeve and provides power for the rotation of the stirring paddle. The first drive assembly is located on one side of the telescopic end of the lifting mechanism and provides power for the rotation of the inner cylinder.

[0017] Furthermore, the filter assembly includes two support rods, both of which are fixed to the outside of the inner cylinder. The two support rods are arranged one above the other, with an included angle of 90 degrees between them. A filter screen is fixedly connected between the two support rods.

[0018] Furthermore, the second drive assembly includes a second drive motor, which is fixedly connected to the top of the outer side of the fixed sleeve. An external gear ring is fixedly connected to the top outer side of the stirring paddle. A drive tooth is fixedly connected to the output end of the second drive motor, and the second drive motor is engaged with the external gear ring through the drive tooth at its output end.

[0019] Furthermore, the first drive assembly includes a drive motor, which is fixedly connected to the telescopic end of the lifting mechanism via a fixed frame. An internal gear ring is fixedly connected to the bottom of the rotating cover, and a drive tooth is fixedly connected to the output end of the drive motor. The drive tooth at the output end of the drive motor meshes with the inner side of the internal gear ring.

[0020] Furthermore, a discharge port is provided on one side of the outer cylinder, and the discharge port is equipped with an opening and closing door.

[0021] Furthermore, in step one, stirring and adding tin chloride is carried out between the outer and inner cylinders. The inner cylinder is rotated by the first drive component, thereby stirring the liquid between the inner and outer cylinders. At the same time, the ZnSn(OH)6 primary particles generated by hydrolysis are stirred and sieved by the filter stirring component. The agglomerated particles will remain on the screen. Next, the lifting mechanism is activated to push the rotating cover to move the inner cylinder upward, thereby separating the primary particles from the solution. In step two, sodium hydroxide particles are added to the inner cylinder. Then, downward ultrasound is applied above the filter stirring component to disperse the agglomerated particles away from the screen, thereby introducing the primary particles in step two. Finally, the stirring paddle is rotated by the second drive component, thereby stirring the liquid a second time.

[0022] Furthermore, the frequency of the ultrasound is 35-40kHz, the ultrasound time is not less than 10min, the stirring parameters in all steps are 700-1200rpm for 0.5-1h, and the mesh size of the filter screen is 7000 mesh.

[0023] Advantages and effects

[0024] (1) The preparation method of this patent can effectively achieve the separation and synergistic effect of primary ZnSn(OH)6 particles desorbed by water and secondary ZnSn(OH)6 particles generated by reaction with sodium hydroxide. This is beneficial for the uniform and fine precipitated particles and avoids the situation of excessively large particle size and huge size difference caused by the non-uniform nucleation of primary particles, thus ensuring the fineness and uniformity of the precursor suspended particles. The highly active surface exposed by the Archimedean ZnSnO3 particles attracts the growth of In2O3 nanoparticles. While forming a uniform In2O3 nanoparticle layer on the multidimensional surface, the Archimedean morphology is retained. The Archimedean morphology exposes more highly active surfaces, providing more reactive sites for gas-sensitive reactions, which is beneficial for gas adsorption and reaction. This is a key factor in improving gas-sensitive performance at low temperatures.

[0025] (2) The low-temperature gas-sensitive composite material with an In2O3 layer grown on the surface of Archimedean ZnSnO3 prepared in this invention uses Archimedean ZnSnO3 as a substrate, and In2O3 nanoparticles are grown on the surface of Archimedean ZnSnO3 to form a composite indium-containing layer. The In2O3 nanoparticles and the multidimensional surface of ZnSnO3 are in full contact to form an n-type heterojunction. Since the Fermi level of In2O3 is higher than that of ZnSnO3, electrons will transfer from the conduction band of In2O3 to the conduction band of ZnSnO3, resulting in the formation of an electron depletion layer and a contact barrier at the interface between the two. This makes the ZnSnO3 / In2O3 composite material have a higher base resistance in air and better gas sensing performance.

[0026] (3) This invention employs a one-step hydrothermal method without the need for structure modifiers, enabling dual detection of ethylene glycol and triethylamine gases by adjusting the operating temperature. At an operating temperature of 100℃, the composite material achieves sensitivities of 3817 and 80 for 100 ppm and 1 ppm ethylene glycol, respectively; and 2176 for 100 ppm triethylamine at an operating temperature of 180℃. The low-temperature gas-sensitive composite material with an In2O3 layer grown on the surface of Archimedean ZnSnO3 prepared in this invention exhibits high sensitivity to both ethylene glycol and triethylamine gases, operates at low temperatures, and has low preparation costs, showing promising prospects for industrial applications. Attached Figure Description

[0027] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. The scope of protection of the present invention is not limited to the descriptions below.

[0028] Figure 1 The image shows the XRD pattern of the low-temperature gas-sensitive material with an In2O3 layer grown on the surface of ZnSnO3 prepared in Example 3.

[0029] Figure 2 This is a microscopic morphology image of the low-temperature gas-sensitive material with an In2O3 layer grown on the surface of ZnSnO3 prepared in Example 3;

[0030] Figure 3 The graph shows the BJH adsorption and pore size distribution of the low-temperature gas-sensitive material with an In2O3 layer grown on the surface of ZnSnO3 prepared in Example 3.

[0031] Figure 4 The image shows the gas-sensing performance of the low-temperature gas-sensitive material with an In2O3 layer grown on the surface of ZnSnO3 prepared in Example 3 to ethylene glycol.

[0032] Figure 5 The image shows the gas-sensing performance of the low-temperature gas-sensitive material with an In2O3 layer grown on the surface of ZnSnO3 prepared in Example 3 to triethylamine.

[0033] Figure 6 This is a microscopic morphology image of the low-temperature gas-sensitive material with an In2O3 layer grown on the surface of ZnSnO3 and a pelletized outer shell prepared in Example 4.

[0034] Figure 7 This is a schematic diagram of the overall structure of the double-layer stirring device;

[0035] Figure 8 This is a cross-sectional view of the overall structure of the double-layer stirring device;

[0036] Figure 9 A schematic diagram of the filter assembly of a double-layer stirring device;

[0037] Figure 10 This is a schematic diagram showing the connection structure between the lifting mechanism and the inner cylinder of the double-layer stirring device.

[0038] Figure 11 This is a schematic diagram of the first drive component of the double-layer stirring device.

[0039] Figure 12 This is a schematic diagram of the second drive component of the double-layer stirring device.

[0040] Explanation of reference numerals in the attached figures:

[0041] 1. Outer cylinder; 2. Inner cylinder; 3. Filter screen stirring assembly; 4. Fixing sleeve; 5. Stirring paddle; 6. First drive assembly; 7. Second drive assembly; 8. Support rod; 9. Filter screen; 10. Lifting mechanism; 11. Connecting sleeve; 12. Rotating cover; 13. Drive motor one; 14. Inner gear ring; 15. Drive motor two; 16. Outer gear ring; 17. Opening and closing door. Detailed Implementation

[0042] All chemical reagents used in the embodiments of this invention are commercially available. Microscopic morphology detection in these embodiments was performed using a SU-8010 field emission scanning electron microscope. Pore structure detection in these embodiments was performed using a Vsorb 2800P surface area and pore size analyzer. The centrifuge used in these embodiments is an LDZ4-1.8 centrifuge; the lifting mechanism is a commercially available non-rotatable telescopic rod; drive motor one and drive motor two are commercially available conventional geared motors.

[0043] A low-temperature gas-sensitive material with an In2O3 layer grown on the surface of ZnSnO3. ZnSnO3 is an Archimedean particle with a particle size ranging from 500 to 900 nm. In the multidimensional surface of the Archimedean, each triangular face is surrounded by three quadrilateral faces, and each quadrilateral face shares an edge with the triangular face. The side length of each side ranges from 300 to 700 nm. In2O3 particles with a particle size ranging from 5 to 50 nm are grown on the multidimensional surface of the ZnSnO3 Archimedean particles to form a uniformly distributed In2O3 particle composite layer.

[0044] Furthermore, the powder particle size of the low-temperature gas-sensitive material with an In2O3 layer grown on the ZnSnO3 surface is 0.7-1.5 μm. The In2O3 nanoparticle layer grows layer by layer along the multidimensional surface, with a thickness ranging from 200-600 nm, forming a ZnSnO3 / In2O3 composite structure with nanoparticle layers coating the multidimensional surface. When the In2O3 nanoparticle layer thickness is greater than or equal to 200 nm and less than 400 nm, the In2O3 particles grow along the multidimensional surface of the ZnSnO3 Archimedean body while maintaining the Archimedean morphology. When the In2O3 nanoparticle layer thickness is greater than or equal to 400 nm and less than or equal to 600 nm, a ZnSnO3 / In2O3 low-temperature gas-sensitive composite material is formed with an Archimedean body substrate and a spheroidized In2O3 outer shell. The specific surface area of ​​the ZnSnO3 / In2O3 composite material reaches 42-65 m². 2 / g, containing micropores of 0.8-1.8nm and mesopores of 2.2-40nm.

[0045] A method for preparing a low-temperature gas-sensitive material with an In2O3 layer grown on a ZnSnO3 surface, the method steps are as follows:

[0046] Step 1: Dissolve zinc oxalate in deionized water at room temperature and stir to make its concentration 2.625-3.325 g / 100 mL. Add tin chloride during stirring. The molar ratio of zinc oxalate to tin chloride is 1:(1-1.1). ZnSn(OH)6 primary particles precipitate out. After stirring and sieving, solution A is obtained.

[0047] Step 2: Add sodium hydroxide particles with a particle size of 16-20 mesh to solution A obtained in Step 1. The molar ratio of zinc oxalate to sodium hydroxide is 1:(9-12). Let stand for 10-20 minutes to precipitate secondary ZnSn(OH)6 particles. Introduce primary ZnSn(OH)6 particles and then continue stirring for 10-20 minutes to obtain suspension B containing Archimedes-shaped ZnSn(OH)6 precursor particles.

[0048] Step 3: Dissolve indium nitrate in deionized water to obtain an indium nitrate aqueous solution with a concentration of 0.1203-0.9024 g / 100 mL. The molar ratio of zinc oxalate to indium nitrate is 1:(0.02-0.15). At room temperature, slowly add the indium nitrate aqueous solution dropwise to the suspension B obtained in Step 2 at a rate of 0.08-0.2 mL / s. Stir continuously at 700-1200 rpm for 0.5-1 h to obtain a white suspension C. Transfer the white suspension C to a reaction vessel with a filling volume ratio of (1.75-1.9):5. Perform a hydrothermal reaction at a temperature of 80-120℃ and a pressure of 35-40 MPa for 8-12 h. Allow it to cool naturally to room temperature to obtain a milky white suspension D.

[0049] Step 4: Transfer the milky white suspension D obtained in Step 3 to a centrifuge and centrifuge at 3000-4500 rpm. Wash the white solid obtained by centrifugation with deionized water and ethanol alternately 3-5 times, and then place it in an oven at 60-75℃ and dry it in air for 10-18 hours. Place the dried powder in a muffle furnace and calcine it in air for 100-140 minutes. Start heating from room temperature at a rate of 2-5℃ / min and calcine at a temperature of 400-550℃ to finally obtain a low-temperature gas-sensitive material with an In2O3 layer grown on the surface of ZnSnO3.

[0050] like Figures 7-12 As shown, steps one and two are completed in a double-layer mixing device, which includes an outer cylinder 1 and an inner cylinder 2. A discharge port is provided on one side of the outer cylinder 1, and the discharge port is equipped with an opening / closing door 17. The opening / closing door 17 is outward-opening, preferably hinged to one side of the outer cylinder 1, and fixed to the other side by a pin. The inner cylinder 2 is located inside the outer cylinder 1. A filter screen mixing assembly 3 is provided between the inner cylinder 2 and the outer cylinder 1, and the filter screen mixing assembly 3 is fixed to the outside of the inner cylinder 2. A fixing sleeve 4 is provided inside the inner cylinder 2, and the bottom of the fixing sleeve 4 is fixedly connected to the bottom of the outer cylinder 1. A mixing paddle 5 is fitted onto the outside of the fixing sleeve 4. A lifting mechanism 10 is fixedly installed inside the cylinder 4. The telescopic end of the lifting mechanism 10 is rotatably connected to the top of the inner cylinder 2. A connecting sleeve 11 is fixedly connected to the top of the telescopic end of the lifting mechanism 10. A rotating cover 12 is fitted on the outside of the connecting sleeve 11. The rotating cover 12 is rotatably connected to the connecting sleeve 11, and the edge of the rotating cover 12 is fixedly connected to the inner cylinder 2. The cylinder also includes a first drive assembly 6 and a second drive assembly 7. The second drive assembly 7 is located at the top of the outer side of the fixed sleeve 4 and provides power for the rotation of the stirring paddle 5. The first drive assembly 6 is located on one side of the telescopic end of the lifting mechanism 10 and provides power for the rotation of the inner cylinder 2. The fixed sleeve 4 is preferably fixed to the lifting mechanism by screws or bolts. While fixing the lifting mechanism, the fixed sleeve 4 also has a wiring channel on its inner side. The wiring channel is connected to the bottom of the fixed sleeve 4. The wires of the lifting mechanism, drive motor one, and drive motor two are all connected to the outside through the wiring channel.

[0051] The filter assembly 3 includes two support rods 8, both of which are fixed to the outside of the inner cylinder 2. The two support rods 8 are arranged one above the other, and the included angle between the two support rods 8 is 90 degrees. A filter screen 9 is fixedly connected between the two support rods 8.

[0052] The second drive assembly 7 includes a second drive motor 15, which is fixedly connected to the top outer side of the fixed sleeve 4. An external gear ring 16 is fixedly connected to the top outer side of the stirring paddle 5. A drive tooth is fixedly connected to the output end of the second drive motor 15, and the drive tooth of the second drive motor 15 meshes with the external gear ring 16. The first drive assembly 6 includes a first drive motor 13, which is fixedly connected to the telescopic end of the lifting mechanism 10 via a fixed bracket. An internal gear ring 14 is fixedly connected to the bottom of the rotating cover 12. A drive tooth is fixedly connected to the output end of the first drive motor 13, and the drive tooth of the first drive motor 13 meshes with the inner side of the internal gear ring 14. It should be emphasized that, unless otherwise specified, the above-mentioned fixed connection structures are all conventional screws, bolts, or welding connections.

[0053] More specifically, in step one, tin chloride is added and stirred between the outer cylinder 1 and the inner cylinder 2. The inner cylinder 2 is rotated by the first drive component 6, thereby stirring the liquid between the inner cylinder 2 and the outer cylinder 1. At the same time, the ZnSn(OH)6 primary particles generated by hydrolysis are stirred and sieved by the filter stirring component 3. Agglomerated particles will remain on the screen. Next, the lifting mechanism 10 is activated to push the rotating cover 12 to move the inner cylinder 2 upward, thereby separating the primary particles from the solution. In step two, sodium hydroxide particles are added to the inner cylinder 1 to minimize the adhesion of secondary particles to the primary particles. Next, downward ultrasound is applied above the filter stirring component 3 to disperse the agglomerated particles away from the screen, thereby introducing the primary particles in step two. Finally, the stirring paddle 5 is rotated by the second drive component 7, thereby stirring the liquid a second time. The ultrasonic frequency is 35-40kHz, the ultrasonic time is not less than 10min, the stirring parameters in all steps are 700-1200rpm for 0.5-1h, and the mesh size of filter screen 9 is 7000 mesh.

[0054] Example 1

[0055] A method for preparing a low-temperature gas-sensitive material with an In2O3 layer grown on the surface of ZnSnO3, the method steps are as follows: Step 1: Under room temperature conditions, zinc oxalate is dissolved in deionized water and stirred to make its concentration 2.625g / 100mL. During the stirring process, tin chloride is added, and the molar ratio of zinc oxalate to tin chloride is 1:(1-1.1). ZnSn(OH)6 primary particles are precipitated. After stirring and sieving, solution A1 is obtained.

[0056] Step 2: Add sodium hydroxide particles with a particle size of 16-20 mesh to solution A1 obtained in Step 1. The molar ratio of zinc oxalate to sodium hydroxide is 1:9. Let stand for 10 minutes to precipitate secondary ZnSn(OH)6 particles. Introduce primary ZnSn(OH)6 particles and then stir continuously for 10 minutes to obtain suspension B1 containing Archimedes-shaped ZnSn(OH)6 precursor particles.

[0057] Step 3: Dissolve indium nitrate in deionized water to obtain an indium nitrate aqueous solution with a concentration of 0.1203 g / 100 mL. The molar ratio of zinc oxalate to indium nitrate is 1:0.02. Under room temperature conditions, the indium nitrate aqueous solution is slowly added dropwise to the suspension B1 obtained in Step 2 at a rate of 0.08 mL / s. After stirring continuously at 700 rpm for 0.5 h, a white suspension C1 is obtained. The white suspension C1 is then transferred to a reaction vessel with a filling volume ratio of 0.35:1. The reaction is carried out hydrothermally at 80 °C and 35 MPa for 8 h. After naturally cooling to room temperature, a milky white suspension D1 is obtained.

[0058] Step 4: Transfer the milky white suspension D1 obtained in Step 3 to a centrifuge and centrifuge at 3000 rpm. Wash the resulting white solid alternately with deionized water and ethanol 3-5 times, then place it in a 60℃ oven and dry it in air for 10 hours. Place the dried powder in a muffle furnace and calcine it in air for 100 minutes at a heating rate of 2℃ / min to a calcination temperature of 400℃. Finally, a low-temperature gas-sensitive material with an In2O3 layer grown on the surface of ZnSnO3 is obtained.

[0059] Example 2

[0060] Step 1: Dissolve zinc oxalate in deionized water at room temperature and stir to make its concentration 2.855 g / 100 mL. Add tin chloride during stirring. The molar ratio of zinc oxalate to tin chloride is 1:(1-1.1). ZnSn(OH)6 primary particles are precipitated. After stirring and sieving, solution A2 is obtained.

[0061] Step 2: Add sodium hydroxide particles with a particle size of 16-20 mesh to solution A2 obtained in Step 1. The molar ratio of zinc oxalate to sodium hydroxide is 1:10. Let stand for 12 minutes to precipitate secondary ZnSn(OH)6 particles. Introduce primary ZnSn(OH)6 particles and then stir continuously for 13 minutes to obtain suspension B2 containing Archimedes-shaped ZnSn(OH)6 precursor particles.

[0062] Step 3: Dissolve indium nitrate in deionized water to obtain an indium nitrate aqueous solution with a concentration of 0.381 g / 100 mL. The molar ratio of zinc oxalate to indium nitrate is 1:0.05. Under room temperature conditions, the indium nitrate aqueous solution is slowly added dropwise to the suspension B2 obtained in Step 2 at a rate of 0.12 mL / s. After stirring continuously at 800 rpm for 40 min, a white suspension C2 is obtained. The white suspension C2 is then transferred to a reaction vessel with a filling volume ratio of 0.36:1. The reaction is carried out hydrothermally at a temperature of 90 °C and a pressure of 37 MPa for 9 h. After naturally cooling to room temperature, a milky white suspension D2 is obtained.

[0063] Step 4: Transfer the milky white suspension D2 obtained in Step 3 to a centrifuge and centrifuge at 3500 rpm. Wash the resulting white solid alternately with deionized water and ethanol 3-5 times, then place it in a 62℃ oven and dry it in air for 12 hours. Place the dried powder in a muffle furnace and calcine it in air for 110 minutes at a heating rate of 3℃ / min to a calcination temperature of 450℃. Finally, a low-temperature gas-sensitive material with an In2O3 layer grown on the surface of ZnSnO3 is obtained.

[0064] Example 3

[0065] Step 1: Dissolve zinc oxalate in deionized water at room temperature and stir to make its concentration 3.085 g / 100 mL. Add tin chloride during stirring. The molar ratio of zinc oxalate to tin chloride is 1:(1-1.1). ZnSn(OH)6 primary particles are precipitated. After stirring and sieving, solution A3 is obtained.

[0066] Step 2: Add sodium hydroxide particles with a particle size of 16-20 mesh to the solution A3 obtained in Step 1. The molar ratio of zinc oxalate to sodium hydroxide is 1:11. Let it stand for 14 minutes to precipitate secondary ZnSn(OH)6 particles. Introduce primary ZnSn(OH)6 particles and then continue stirring for 17 minutes to obtain a suspension B3 containing Archimedes-shaped ZnSn(OH)6 precursor particles.

[0067] Step 3: Dissolve indium nitrate in deionized water to obtain an indium nitrate aqueous solution with a concentration of 0.6417 g / 100 mL. The molar ratio of zinc oxalate to indium nitrate is 1:0.1. At room temperature, the indium nitrate aqueous solution is slowly added dropwise to the suspension B3 obtained in Step 2 at a rate of 0.16 mL / s. After stirring continuously at 900 rpm for 50 min, a white suspension C3 is obtained. The white suspension C3 is then transferred to a reaction vessel with a filling volume ratio of 0.37:1. The reaction is carried out hydrothermally at 100 °C and 39 MPa for 10 h. After naturally cooling to room temperature, a milky white suspension D3 is obtained.

[0068] Step 4: Transfer the milky white suspension D3 obtained in Step 3 to a centrifuge and centrifuge at 4000 rpm. Wash the resulting white solid alternately with deionized water and ethanol 3-5 times, then place it in a 64℃ oven and dry it in air for 16 hours. Place the dried powder in a muffle furnace and calcine it in air for 120 minutes at a heating rate of 4℃ / min to a calcination temperature of 500℃. Finally, a low-temperature gas-sensitive material with an In2O3 layer grown on the surface of ZnSnO3 is obtained.

[0069] Example 4

[0070] Step 1: Dissolve zinc oxalate in deionized water at room temperature and stir to make its concentration 3.085 g / 100 mL. Add tin chloride during stirring. The molar ratio of zinc oxalate to tin chloride is 1:(1-1.1). ZnSn(OH)6 primary particles are precipitated. After stirring and sieving, solution A4 is obtained.

[0071] Step 2: Add sodium hydroxide particles with a particle size of 16-20 mesh to solution A obtained in Step 1. The molar ratio of zinc oxalate to sodium hydroxide is 1:12. Let stand for 20 minutes to precipitate secondary ZnSn(OH)6 particles. Introduce primary ZnSn(OH)6 particles and then continue stirring for 20 minutes to obtain suspension B4 containing Archimedes-shaped ZnSn(OH)6 precursor particles.

[0072] Step 3: Dissolve indium nitrate in deionized water to obtain an indium nitrate aqueous solution with a concentration of 0.9024 g / 100 mL. The molar ratio of zinc oxalate to indium nitrate is 1:0.15. At room temperature, the indium nitrate aqueous solution is slowly added dropwise to the suspension B4 obtained in Step 2 at a rate of 0.2 mL / s. After stirring continuously at 1200 rpm for 1 h, a white suspension C4 is obtained. The white suspension C4 is then transferred to a reaction vessel with a filling volume ratio of 0.38:1. The reaction is carried out hydrothermally at 120 °C and 40 MPa for 12 h. After naturally cooling to room temperature, a milky white suspension D4 is obtained.

[0073] Step 4: Transfer the milky white suspension D4 obtained in Step 3 to a centrifuge and centrifuge at 4500 rpm. Wash the resulting white solid alternately with deionized water and ethanol 3-5 times, then place it in a 75℃ oven and dry it in air for 18 hours. Place the dried powder in a muffle furnace and calcine it in air for 140 minutes at a heating rate of 5℃ / min to a calcination temperature of 550℃. Finally, a low-temperature gas-sensitive material with an In2O3 layer grown on the surface of ZnSnO3 is obtained.

[0074] Performance testing:

[0075] To test the performance of the low-temperature gas-sensitive material with an In2O3 layer grown on the surface of ZnSnO3 prepared by the method of the present invention, the low-temperature gas-sensitive material with an In2O3 layer grown on the surface of ZnSnO3 prepared in Example 3 was first ground in a mortar for 30 minutes. A mixed solution of ethanol and deionized water was then added, and the material was ground further into a slurry slightly thinner than honey. This slurry was then coated onto the surface of an alumina ceramic tube with a small brush, and subsequently welded to a base. A WS-60A gas-sensitive element tester was then used to test the sensitivity of 100 ppm ethylene glycol and 100 ppm triethylamine under different temperature conditions.

[0076] The test results for ethylene glycol are as follows Figure 4 As shown, the horizontal axis represents the operating temperature, and the vertical axis represents the sensitivity. The sensitivity reaches 3817 at an operating temperature of 100℃.

[0077] The results of the triethylamine test are as follows Figure 5 As shown, the horizontal axis represents the operating temperature, and the vertical axis represents the sensitivity. The sensitivity reaches 2176 at an operating temperature of 180℃.

[0078] Figure 1 The image shows the XRD pattern of the low-temperature gas-sensitive material with an In2O3 layer grown on the ZnSnO3 surface prepared in Example 3. As can be seen from the image, the ZnSnO3 / In2O3 sample exhibits two high-peak main diffraction peaks at 2θ = 33.849° and 60.731°, indicating that ZnSnO3 is the main phase and has good crystallinity. For orthorhombic ZnSnO3, its (110) and (100) axes have high surface energies. Figure 1 We can observe a high intensity diffraction peak corresponding to the (110) crystal plane, indicating that the preparation of Archimedean ZnSnO3 is beneficial to the exposure of the highly active crystal plane (110). Diffraction peaks of In2O3 were observed at 2θ = 30.565°, 2θ = 35.466° and 2θ = 51.029°, proving the existence of the second phase In2O3 and indicating the successful preparation of ZnSnO3 / In2O3 composite material. According to existing research, the calcination and dehydration process during the preparation of ZnSnO3 breaks the original hydrogen-oxygen bonds, changes the internal lattice arrangement of ZnSnO3, and thus forms amorphous ZnSnO3, which is shown as a weak and broad peak in the XRD pattern. The high intensity of the diffraction peaks at 2θ = 33.849° and 60.731° of the ZnSnO3 / In2O3 composite material indicates that the ZnSnO3 / In2O3 composite material has a good degree of crystallization. The successful preparation of the ZnSnO3 / In2O3 heterostructure is beneficial to improving the sensitivity of the ZnSnO3 / In2O3 composite material.

[0079] Figure 2The image shows the microstructure of a low-temperature gas-sensitive material with an In2O3 layer grown on a ZnSnO3 surface. The ZnSnO3 particles are Archimedean particles with a diameter ranging from 500 to 900 nm. Each triangular facet of the Archimedean particle has three quadrilateral faces surrounding it, with each quadrilateral facet sharing an edge with the triangular facet. The side length of each side ranges from 300 to 700 nm. In2O3 particles with a diameter ranging from 5 to 50 nm grow on the multidimensional surface of the ZnSnO3 Archimedean particles, forming a uniformly distributed In2O3 particle composite layer. The thickness of the In2O3 particle composite layer increases with the increase of the indium source, but the Archimedean morphology is maintained even when the amount of indium source increases to the range of Example 3. On the highly active surface exposed by the ZnSnO3 multidimensional substrate, ZnSnO3 and In2O3 form an n-type heterojunction. In order to achieve Fermi level equilibrium, electrons will flow from In2O3 to ZnSnO3, thereby increasing the depletion layer thickness. This leads to an increase in the resistance of the ZnSnO3 / In2O3 composite material in air, thus improving gas sensitivity.

[0080] Figure 3 The BJH adsorption and pore size distribution curves of the low-temperature gas-sensitive material with an In2O3 layer grown on a ZnSnO3 surface are shown. The curves indicate that the composite material exhibits a Type IV isotherm, suggesting a relatively weak interaction between the adsorbent and adsorbate. Higher relative pressure results in greater adsorption, indicating pore filling. The pore size distribution diagram reveals that the composite material contains micropores of 0.8-1.8 nm and mesopores of 2.2-40 nm. This well-developed pore structure facilitates the arrival of more gas molecules at the ZnSnO3 and In2O3 interface, accelerating the gas diffusion rate and thus enhancing the gas-sensing performance.

[0081] Figure 4 The graph shows the gas-sensing performance of a low-temperature gas-sensitive material with an In2O3 layer grown on the surface of ZnSnO3 for ethylene glycol. It is a curve showing the sensitivity of the low-temperature gas-sensitive composite material with an In2O3 layer grown on the surface of Archimedesic ZnSnO3 to 100 ppm ethylene glycol as a function of temperature. The detection operating temperature can be reduced to 80-100℃, and its sensitivity can reach 3817 at a concentration of 100 ppm ethylene glycol.

[0082] Figure 5 The graph shows the gas-sensing performance of a low-temperature gas-sensitive material with an In2O3 layer grown on a ZnSnO3 surface to triethylamine. It depicts the sensitivity of the Archimedean ZnSnO3 composite material to 100 ppm triethylamine as a function of temperature. The optimal operating temperature for triethylamine gas is 180℃, and its response value to 100 ppm triethylamine gas is 2176. (Combined with...) Figure 5This demonstrates that the low-temperature gas-sensitive composite material with an In2O3 layer grown on the surface of Archimedesic ZnSnO3 can selectively detect ethylene glycol and triethylamine gases by adjusting the operating temperature.

[0083] Figure 6 The image shows the microstructure of the low-temperature gas-sensitive material prepared in Example 4, in which an In2O3 layer is grown on the surface of ZnSnO3 and the outer shell is spheroidized. The diameter of the ZnSnO3 / In2O3 composite spheroidized particles is approximately 0.7-1.5 μm. The spheroidized morphology is due to the excessive addition of the indium source. When the thickness of the In2O3 particle composite layer reaches 400 nm, the energy of the newly nucleated particles on the surface is higher than that of the grains within the composite layer. The higher-energy In2O3 nanoparticles tend to detach from the surface of the Archimedean bulk particles and dissolve into the solvent. As the supersaturation of the solvent increases, the In2O3 particles will condense and stack layer by layer along the surface of the ZnSnO3 particles, filling the edges and corners of the multidimensional surface of ZnSnO3, thus causing the outer shell of the ZnSnO3 / In2O3 composite powder to spheroidize.

[0084] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all embodiments here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A low temperature gas sensitive material of ZnSn03 surface grown with a layer of In203, characterized in that: ZnSnO3 is an Archimedean solid particle, the particle size range is 500-900nm, in the multi-dimensional surface of the Archimedean solid, there are three quadrilateral faces around each triangular face, each quadrilateral face shares a side with the triangular face, and the length of each side ranges from 300-700nm; In2O3 particles with a particle size range of 5-50nm grow on the multi-dimensional surface of the ZnSnO3 Archimedean solid particle, forming a uniformly distributed In2O3 particle composite layer.

2. The low temperature gas sensitive material of claim 1, wherein the In203 layer is grown on the surface of ZnSn03. The powder particle size of the low-temperature gas-sensitive material with In2O3 layer grown on ZnSnO3 surface is 0.7-1.5 μm, the In2O3 nanoparticle layer grows along the multi-dimensional surface layer by layer, the thickness of the In2O3 nanoparticle layer ranges from 200 nm to 600 nm, and the ZnSnO3 / In2O3 composite structure with the nanoparticle layer covering the multi-dimensional surface is formed; when the thickness of the In2O3 nanoparticle layer is greater than or equal to 200 nm and less than 400 nm, the In2O3 particles grow along the multi-dimensional surface of the ZnSnO3 Archimedean solid and keep the Archimedean solid morphology, and when the thickness of the In2O3 nanoparticle layer is greater than or equal to 400 nm and less than or equal to 600 nm, the ZnSnO3 / In2O3 low-temperature gas-sensitive composite material with the ZnSnO3 substrate as the Archimedean solid and the In2O3 shell layer as the pellet is formed; the specific surface area of the ZnSnO3 / In2O3 composite material reaches 42-65 m 2 / g, containing micropores of 0.8-1.8 nm and mesopores of 2.2-40 nm.

3. A method for producing a low-temperature gas-sensing material of ZnSn03 on which an In203 layer is grown, as claimed in claim 1 or 2, characterized by: The method steps are as follows: Step one, under room temperature conditions, dissolve zinc oxalate in deionized water and stir to make its concentration 2.625-3.325g / 100mL, add tin chloride during stirring, the molar ratio of zinc oxalate to tin chloride is 1:(1-1.1), ZnSn(OH)6 primary particles are precipitated, after stirring and sieving, solution A is obtained; Step two, add sodium hydroxide particles with a particle size of 16-20 mesh to the solution A obtained in step one, the molar ratio of zinc oxalate to sodium hydroxide is 1:(9-12), stand for 10-20 minutes, ZnSn(OH)6 secondary particles are precipitated, introduce ZnSn(OH)6 primary particles, then continue stirring for 10-20 minutes, obtain suspension B containing ZnSn(OH)6 precursor particles with Archimedean solid shape; Step three, dissolve indium nitrate in deionized water to obtain an indium nitrate aqueous solution with a concentration of 0.1203-0.9024g / 100mL, the molar ratio of zinc oxalate to indium nitrate is 1:(0.02-0.15), under room temperature conditions, slowly drop the indium nitrate aqueous solution into the suspension B obtained in step two at a speed of 0.08-0.2mL / s, continue stirring at a speed of 700-1200rpm for 0.5-1h to obtain white suspension C, and transfer the white suspension C to a reaction kettle, the filling ratio is (1.75-1.9):5, hydrothermal reaction is carried out at a temperature of 80-120℃ and a pressure of 35-40Mpa for 8-12h, and naturally cool to room temperature to obtain a cream white suspension D; Step four, transfer the cream white suspension D obtained in step three to a centrifuge for 3000-4500rpm centrifugation, wash the white solid obtained by centrifugation with deionized water and ethanol alternately for 3-5 times, then place it in a 60-75℃ oven, dry in air atmosphere for 10-18h, place the dried powder in a muffle furnace, calcine in air atmosphere for 100-140min, start heating at room temperature, the heating rate is 2-5℃ / min, the calcination temperature is 400-550℃, and finally obtain a low-temperature gas sensitive material of ZnSnO3 surface growth In2O3 layer.

4. The method of claim 3, wherein the method is characterized by: The step one and step two are completed in a double-layer stirring device, the double-layer stirring device includes an outer cylinder (1) and an inner cylinder (2), the inner cylinder (2) is arranged on the inner side of the outer cylinder (1), a filter screen stirring assembly (3) is arranged between the inner cylinder (2) and the outer cylinder (1), the filter screen stirring assembly (3) is fixed on the outer side of the inner cylinder (2), a fixed sleeve (4) is arranged on the inner side of the inner cylinder (2), the bottom of the fixed sleeve (4) is fixedly connected with the bottom of the outer cylinder (1), a stirring paddle (5) is sleeved on the outer side of the fixed sleeve (4), a jacking mechanism (10) is fixedly arranged in the fixed sleeve (4), the telescopic end of the jacking mechanism (10) is rotatably connected with the top of the inner cylinder (2), a connecting sleeve (11) is fixedly connected with the top of the telescopic end of the jacking mechanism (10), a rotary cover (12) is sleeved on the outer side of the connecting sleeve (11), the rotary cover (12) is rotatably connected with the connecting sleeve (11), and the edge of the rotary cover (12) is fixedly connected with the inner cylinder (2). Further comprising a first driving assembly (6) and a second driving assembly (7), the second driving assembly (7) is arranged at the position of the top of the outer side of the fixed sleeve (4), and is used for providing power for the rotation of the stirring paddle (5); the first driving assembly (6) is arranged at the position of one side of the telescopic end of the jacking mechanism (10), and is used for providing power for the rotation of the inner cylinder (2).

5. The method of claim 4, wherein the method is characterized by: The filter screen stirring assembly (3) comprises two support rods (8), the two support rods (8) are fixed on the outer side of the inner cylinder (2), the two support rods (8) are arranged one above the other, the included angle between the two support rods (8) is ninety degrees, and a filter screen (9) is fixedly connected between the two support rods (8).

6. The method of claim 4, wherein the method is characterized by: The second driving assembly (7) comprises a second driving motor (15), the second driving motor (15) is fixedly connected with the top of the outer side of the fixed sleeve (4), an outer gear ring (16) is fixedly connected with the top of the outer side of the stirring paddle (5), a driving gear is fixedly connected with the output end of the second driving motor (15), and the second driving motor (15) is connected with the outer gear ring (16) in a meshing mode through the driving gear of the output end.

7. The method of claim 4, wherein the method is characterized by: The first driving assembly (6) comprises a first driving motor (13), the first driving motor (13) is fixedly connected with the telescopic end of the jacking mechanism (10) through a fixed frame, an inner gear ring (14) is fixedly connected with the bottom of the rotary cover (12), a driving gear is fixedly connected with the output end of the first driving motor (13), and the driving gear of the output end of the first driving motor (13) is connected with the inner side of the inner gear ring (14) in a meshing mode.

8. The method of claim 4, wherein the method is characterized by: One side of the outer cylinder (1) is provided with a discharge port, and the discharge port is provided with an opening and closing door (17).

9. The method of claim 4, wherein the method is characterized by: The first step is to stir and add tin chloride between the outer cylinder (1) and the inner cylinder (2), the inner cylinder (2) is driven to rotate by the first driving assembly (6), so as to stir the liquid between the inner cylinder (2) and the outer cylinder (1), and the ZnSn(OH)6 primary particles generated by hydrolysis are stirred and sieved by the filter screen stirring assembly (3), the agglomerated particles are retained on the screen, then the primary particles and the solution are separated by starting the jacking mechanism (10) to push the rotating cover (12) to move the inner cylinder (2) upward, then sodium hydroxide particles are added to the inner cylinder (1) in the second step, then the agglomerated particles are scattered away from the screen to realize the introduction of primary particles in the second step by applying downward ultrasound to the upper part of the filter screen stirring assembly (3), then the stirring paddle (5) is driven to rotate by the second driving assembly (7), so as to stir the liquid by the stirring paddle (5) for the second time.

10. The method of claim 9, wherein the method is characterized by: The frequency of the ultrasound is 35-40 kHz, the ultrasound time is not less than 10 min, the stirring parameters in all steps are 700-1200 rpm speed stirring for 0.5-1 h, and the mesh number of the filter screen (9) is 7000 meshes.

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