A composite material of indium-poor tungsten bronze phase mosaic block assembly and a preparation method thereof

Abstract

The present application relates to a kind of indium-poor tungsten bronze phase mosaic block assembled composite material and its preparation method, and the indium-poor tungsten bronze phase mosaic block assembled composite material is by In 0.02 WO3 is formed by WO3 compound, there are many tunnels consisting of the interval between tungsten and oxygen atom in the indium-poor tungsten bronze phase mosaic block assembled composite material, and indium ions are randomly distributed on both sides of the tunnel center position.Method: step one, create supersaturated sodium sulfate solution environment;Step two, in the supersaturated sodium sulfate solution environment obtained in step one, add indium nitrate, add NH4Cl hydrothermal reaction;Step three, centrifugation;Step four, sodium tungstate, oxalic acid and ammonium chloride are sequentially added to deionized water, drop into HCL, add the product of step three hydrothermal reaction, centrifugation and washing, finally the indium-poor tungsten bronze phase mosaic block assembled composite material is prepared.The material has high sensitivity to acetone gas, and the working temperature is low.

Description

Technical Field

[0001] This invention belongs to the field of metal oxide semiconductor nanomaterials technology, and relates to a composite material assembled from indium-poor tungsten bronze phase mosaic blocks and its preparation method. Background Technology

[0002] Common toxic gases in the atmosphere include CO, SO2, NO2, and H2S. High concentrations of these gases can cause acute poisoning in humans, and even serious consequences such as physiological dysfunction. Furthermore, long-term exposure to volatile organic compounds (VOCs) from building materials, vehicle exhaust, fuel combustion, and industrial production, even at low concentrations, can cause chronic poisoning, severely damaging the nervous system, blood system, and even the brain development of children. Therefore, the research and development of tungsten oxide-based gas sensors with rapid response to harmful gases, good selectivity and stability, low optimal operating temperature, and excellent gas sensitivity has become a current research hotspot.

[0003] The most widely used sensing mechanism for tungsten-based semiconductor gas sensors is the adsorption-desorption model. This model refers to the change in the electrical properties of a gas-sensitive material caused by adsorption or desorption reactions of the monitored gas on its surface, thereby achieving gas detection. Therefore, the gas-sensing performance of a material is closely related to its effective specific surface area, inherent structure and defects, and the number of active sites, a fact confirmed in numerous reports.

[0004] To address the high operating temperature issue of tungsten-based gas-sensitive materials and to integrate with the sensing mechanism of tungsten-based gas sensors, the design and development of nanostructured gas-sensitive materials has become a crucial research direction. Numerous experimental studies have demonstrated that multi-dimensional nanostructured gas sensors with excellent gas-sensing performance can be obtained through various methods. These nanostructures, classified by their dimensionality, can be primarily categorized into zero-dimensional nanostructures (nanoparticles, etc.), one-dimensional nanostructures (nanowires, nanotubes, etc.), two-dimensional nanostructures (nanofilms, nanosheets, etc.), three-dimensional nanostructures (urchin-like, flower-like, hollow microspheres, etc.), and multi-dimensional nanostructures assembled from low-dimensional nanostructures. These nanostructures, due to their unique properties such as large specific surface area, good pore structure, and small size effect, exhibit high activity in gas-sensing reactions. This significantly improves the gas-sensing performance of gas-sensitive materials in terms of sensitivity, selectivity, response recovery time, and operating temperature. Furthermore, the gas-sensing performance of tungsten oxide can be further enhanced by controlling its morphology and crystal form or by combining it with other materials. Given the many unique electrical properties of tungsten bronze-type structural materials, multidimensional nanostructured tungsten oxide-based gas-sensitive materials containing tungsten bronze phases have great potential for development in gas detection.

[0005] To date, a two-step hydrothermal method has been used to prepare three-dimensional autonomous devices.0.02 WO3 / WO3 materials have received little research, but their ability to regulate and modify the structure of tungsten oxide is highly feasible. Furthermore, few metal semiconductor oxide sensors can control the detection temperature at or below 100℃. Therefore, it is necessary to develop an In... 0.02 A method for preparing WO3 / WO3 materials to achieve detection temperature control of acetone and other analytes at around 100℃. Summary of the Invention

[0006] Purpose of the invention

[0007] To solve the existing technology In 0.02 The preparation process of WO3 materials is complicated, thermodynamically unstable, has a simple composite microstructure, high degree of agglomeration and small specific surface area. This invention provides a composite material assembled from indium-depleted tungsten bronze phase blocks and its preparation method.

[0008] Technical solution

[0009] A composite material assembled from indium-depleted tungsten bronze phase mosaic blocks, wherein the composite material is composed of indium-depleted tungsten bronze phase mosaic blocks. 0.02 Composed of WO3 and WO3, the composite material assembled from indium-poor tungsten bronze phase inlay blocks contains many tunnels formed by the gaps between tungsten and oxygen atoms, with indium ions randomly distributed on both sides of the center of the tunnels.

[0010] Furthermore, the composite material structure assembled from indium-depleted tungsten bronze phase mosaic blocks consists of numerous hollow spheres. The hollow spheres in a single indium-depleted tungsten bronze phase structure exhibit good dispersion, with a microsphere diameter of 2-3 μm and a thickness of 450 nm-520 nm. Each microsphere contains micropores with a diameter greater than 1 nm and less than or equal to 2 nm, mesopores with a diameter greater than 2 nm and less than or equal to 50 nm, and macropores with a diameter greater than 50 nm and less than or equal to 100 nm. The hollow spheres in a single indium-depleted tungsten bronze phase structure are hollow sphere structures assembled from mosaic block strips, with the mosaic block strips having a length of 50-250 nm, a height of 10-50 nm, and a width of 20-100 nm.

[0011] A method for preparing a composite material assembled from indium-depleted tungsten bronze phase mosaic blocks as described above, comprising the following steps:

[0012] Step 1: Place a container filled with deionized water in a water bath at 50-80℃, add sodium sulfate to the deionized water to make the concentration 5.8-8.2g / 100mL, stir at 500-800rpm for 0.5-1.5h, then quickly place the container filled with deionized water in a 0℃ ice-water mixture and reduce the stirring speed to 100-300rpm within 1s, and continue stirring for 10-20min to create a supersaturated sodium sulfate solution environment;

[0013] Step 2: In the supersaturated sodium sulfate solution obtained in Step 1, indium nitrate is added. The mass ratio of sodium sulfate to indium nitrate is (3.8-4.2):1. At the same time, NH4Cl is added as an active agent and pH adjuster. The mass ratio of NH4Cl to In(NO3)3 is (0.5-2):1. The mixture is stirred at 700-1200 rpm for 0.5-1.5 hours. The container is then transferred from the 0°C ice-water mixture to a hydrothermal reactor with a filling ratio of (3.5-4.2):5. The mixture is then hydrothermally reacted at 160-180°C and a constant pressure of 35-40 MPa for 3-4 hours. After that, the mixture is naturally cooled to 130-160°C and reacted for another 6-10 hours.

[0014] Step 3: Centrifuge the product obtained in Step 2. Transfer the centrifuged solid to a freeze dryer and dry it at -30 to -60°C for 20-40 hours to obtain the indium oxide precursor. Place it in a vacuum chamber, evacuate it, and store it to preserve its activity.

[0015] Step 4: Add sodium tungstate, oxalic acid, and ammonium chloride sequentially to deionized water. The molar ratio of sodium tungstate, oxalic acid, and ammonium chloride is (0.3-1.2):(1-1.2):(0.1-0.5), and the solid-liquid mass ratio is (0.30-0.31):15. Stir at room temperature for 1-2 hours at 1000-1300 rpm. Add 6-10 mol / L HCl to the deionized water at 2-7 drops / s, making the mass ratio of HCl to deionized water (0.8-1.4):6). Continue stirring for 1 hour. -1.5h, add the product from step 3, and heat at 1-3℃ for 50-70min, stirring continuously for 1-3h. Transfer to a hydrothermal reactor with a filling ratio of (3.5-4.2):5, and hydrothermally react at 150-220℃ and 35-40MPa for 5-18h. After natural cooling to room temperature, a yellow suspension mixture is obtained, which is then centrifuged at 3000-4500rpm. The solid obtained by centrifugation is washed with ethanol 3-5 times to finally obtain the composite material assembled from indium-depleted tungsten bronze phase blocks.

[0016] Advantages and effects

[0017] (1) In the composite material structure assembled from indium-poor tungsten bronze phase mosaic blocks, indium ions are distributed at two off-center positions in the tunnels, forming stereochemically active lone pairs (In).1+ 5s2) and W 6+ Coordination and W 6+ 6s² electron activation, according to the thermodynamic law ΔG=ΔH-TΔS, enhances the positive correlation between the system entropy change and temperature on the basis of thermodynamic stability, and reduces the temperature threshold to reach ΔG<0, so as to reduce the operating temperature.

[0018] (2) NH4Cl is used as an active agent and pH adjuster. The hydrolysis of ammonium ions makes the solution weakly acidic, increasing the pH of InSO4·5H2O. + The concentration of Cl - Affected by InSO4·5H2O + Attraction, under high temperature and high pressure, forms a surface covered with Cl. - Indium oxide octahedron (InOCl) x ), which can make W 6+ Electrons are activated and occupy part of the gap, which is In. + The entry provides a tunnel, allowing it to form a uniform and stable HTB phase;

[0019] (3) The preparation method is simple, low-cost, and easy to synthesize. It has high sensitivity to acetone gas and low operating temperature. The high-activity, low-power embedded block strip composite material of this invention is the first in gas-sensitive detection semiconductor materials (operating temperature is 100℃, and the sensitivity to detect 10ppm acetone reaches 119) to achieve a low-temperature detection sensitivity of over 100 for acetone, which has good prospects for industrial application. Attached Figure Description

[0020] Figure 1 Composite materials assembled for indium-depleted tungsten bronze phase inserts (In 0.02 XRD pattern of WO3 / WO3;

[0021] Figure 2 The composite material assembled from the indium-depleted tungsten bronze phase inlay blocks prepared in Example 4 (In 0.02 Microstructure diagram of WO3 / WO3

[0022] Figure 3 The composite material assembled from the indium-depleted tungsten bronze phase inlay blocks prepared in Example 4 (In 0.02 SEM microstructure of WO3 / WO3;

[0023] Figure 4 The composite material assembled from the indium-depleted tungsten bronze phase inlay blocks prepared in Example 4 (In 0.02 BJH adsorption and pore size distribution curves of WO3 / WO3;

[0024] Figure 5The composite material assembled from the indium-depleted tungsten bronze phase inlay blocks prepared in Example 4 (In 0.02 WO3 / WO3)TEM microstructure image;

[0025] Figure 6 The composite material assembled from the indium-depleted tungsten bronze phase inlay blocks prepared in Example 4 (In 0.02 WO3 / WO3) gas-sensitive performance diagram. Detailed Implementation

[0026] All chemical reagents used in the embodiments of this invention are commercially available. Microscopic morphology was detected using a SU-8010 field emission scanning electron microscope. Pore structure was detected using a Vsorb 2800P surface area and pore size analyzer. The centrifuge used in the embodiments of this invention is an LDZ4-1.8 centrifuge.

[0027] A composite material assembled from indium-poor tungsten bronze phase mosaic blocks (In 0.02 WO3 / WO3), a composite material assembled from indium-depleted tungsten bronze phase mosaic blocks, is made of In 0.02 Composed of WO3 and WO3, the composite material assembled from indium-poor tungsten bronze phase inlay blocks contains many tunnels formed by the gaps between tungsten and oxygen atoms, with indium ions randomly distributed on both sides of the center of the tunnels.

[0028] The composite material structure assembled from indium-depleted tungsten bronze phase mosaic blocks consists of numerous hollow spheres. The hollow spheres in a single indium-depleted tungsten bronze phase structure are well dispersed, with a microsphere diameter of 2-3 μm and a thickness of 450 nm-520 nm. The microspheres contain micropores with a diameter greater than 1 nm and less than or equal to 2 nm, mesopores with a diameter greater than 2 nm and less than or equal to 50 nm, and macropores with a diameter greater than 50 nm and less than or equal to 100 nm. The hollow spheres in a single indium-depleted tungsten bronze phase structure are hollow sphere structures assembled from mosaic block strips with a length of 50-250 nm, a height of 10-50 nm, and a width of 20-100 nm.

[0029] A composite material assembled from indium-poor tungsten bronze phase mosaic blocks (In 0.02 The preparation method of WO3 / WO3 is as follows:

[0030] Step 1: Place a container (beaker) containing deionized water in a water bath at 50-80℃, add sodium sulfate to the deionized water to achieve a concentration of 5.8-8.2 g / 100 mL, and stir at 500-800 rpm for 0.5-1.5 h. Immediately place the container containing deionized water in a 0℃ ice-water mixture and reduce the stirring speed to 100-300 rpm within 1 second, continuing to stir for 10-20 min to create a supersaturated sodium sulfate solution environment and form In(SO4)2·5H2O.+ and In(SO4)2·4H2O - Coordination compounds;

[0031] Step 2: In the supersaturated sodium sulfate solution obtained in Step 1, indium nitrate is added. The mass ratio of sodium sulfate to indium nitrate is (3.8-4.2):1. NH4Cl is also added as an active agent and pH adjuster. The ammonium ions hydrolyze, making the solution weakly acidic and increasing the pH of InSO4·5H2O. + The concentration of Cl - Affected by InSO4·5H2O + Attraction, under high temperature and high pressure, forms a surface covered with Cl. - Indium oxide octahedron (InOCl) x ), where x is a positive number, can make W 6+ Electrons are activated and occupy part of the gap, providing In + The entry provides a tunnel; the mass ratio of NH4Cl and In(NO3)3 is (0.5-2):1, and the mixture is stirred at 700-1200 rpm for 0.5-1.5 h. The container is then transferred from the ice-water mixture at 0 degrees Celsius to a hydrothermal reactor with a filling ratio of (3.5-4.2):5. The mixture is then hydrothermally reacted at 160-180℃ and 35-40 MPa constant pressure for 3-4 h, and then naturally cooled to 130-160℃ for another 6-10 h.

[0032] Step 3: Centrifuge the product obtained in Step 2. Transfer the centrifuged solid to a freeze dryer and dry it at -30 to -60°C for 20-40 hours to obtain the indium oxide precursor. Place it in a vacuum chamber, evacuate it, and store it to preserve its activity.

[0033] Step 4: Add sodium tungstate, oxalic acid, and ammonium chloride sequentially to deionized water. The molar ratio of sodium tungstate, oxalic acid, and ammonium chloride is (0.3-1.2):(1-1.2):(0.1-0.5), and the solid-liquid mass ratio is (0.30-0.31):15. Stir at room temperature for 1-2 hours at 1000-1300 rpm. Add 6-10 mol / L HCl to the deionized water at 2-7 drops / s, making the mass ratio of HCl to deionized water (0.8-1.4):6). Continue stirring for 1 hour. -1.5h, add the product from step 3, and heat at 1-3℃ for 50-70min, stirring continuously for 1-3h. Transfer to a hydrothermal reactor with a filling ratio of (3.5-4.2):5, and hydrothermally react at 150-220℃ and 35-40MPa for 5-18h. After natural cooling to room temperature, a yellow suspension mixture is obtained, which is then centrifuged at 3000-4500rpm. The solid obtained by centrifugation is washed with ethanol 3-5 times to finally obtain the composite material assembled from indium-depleted tungsten bronze phase blocks.

[0034] Example 1

[0035] A composite material assembled from indium-poor tungsten bronze phase mosaic blocks (In 0.02 The preparation method of WO3 / WO3 is as follows:

[0036] Step 1: Place a container of deionized water in a 50°C water bath and add sodium sulfate to the deionized water to make the concentration 5.8g / 100mL. Stir at 500rpm for 1.5h. Immediately place the container of deionized water in a 0°C ice-water mixture and reduce the stirring speed to 100rpm within 1s. Continue stirring for 20min to create a supersaturated sodium sulfate solution environment.

[0037] Step 2: In the supersaturated sodium sulfate solution obtained in Step 1, indium nitrate is added. The mass ratio of sodium sulfate to indium nitrate is 3.8:1. NH4Cl is added as an active agent and pH adjuster. The mass ratio of NH4Cl to In(NO3)3 is 0.5:1. The mixture is stirred at 700 rpm for 1.5 hours. The container is then transferred from the 0°C ice-water mixture to a hydrothermal reactor with a filling ratio of 3.5:5. The mixture is hydrothermally reacted at 160°C and a constant pressure of 40 MPa for 4 hours. After that, it is naturally cooled to 130°C and reacted for another 10 hours.

[0038] Step 3: Centrifuge the product obtained in Step 2. Transfer the centrifuged solid to a freeze dryer and dry it at -30°C for 40 hours to obtain the indium oxide precursor. Place it in a vacuum chamber, evacuate it, and store it to preserve its activity.

[0039] Step 4: Sodium tungstate, oxalic acid, and ammonium chloride were added sequentially to deionized water. The molar ratio of sodium tungstate, oxalic acid, and ammonium chloride was 0.3:1:0.1, and the solid-liquid mass ratio was 0.3:15. The mixture was stirred at room temperature for 2 hours at 1000 rpm. HCl (6 mol / L) was added to the deionized water at a rate of 2 drops / s, making the mass ratio of HCl to deionized water 0.8:6. The mixture was stirred for 1 hour. The product from Step 3 was added, and the temperature was increased by 1°C for 50 minutes. The mixture was stirred for 1 hour and then transferred to a hydrothermal reactor with a filling ratio of 3.5:5. The reactor was hydrothermally reacted at 150°C and 40 MPa for 18 hours. After natural cooling to room temperature, a yellow suspension was obtained. The suspension was centrifuged at 3000 rpm. The solid obtained by centrifugation was washed three times with ethanol to finally obtain the composite material assembled from indium-depleted tungsten bronze phase blocks.

[0040] Example 2

[0041] A composite material assembled from indium-poor tungsten bronze phase mosaic blocks (In 0.02 The preparation method of WO3 / WO3 is as follows:

[0042] Step 1: Place a container of deionized water in a 60°C water bath and add sodium sulfate to the deionized water to make the concentration 6.4g / 100mL. Stir at 600rpm for 1.2h. Immediately place the container of deionized water in a 0°C ice-water mixture and reduce the stirring speed to 180rpm within 1s. Continue stirring for 16min to create a supersaturated sodium sulfate solution environment.

[0043] Step 2: In the supersaturated sodium sulfate solution obtained in Step 1, indium nitrate is added. The mass ratio of sodium sulfate to indium nitrate is 3.9:1. NH4Cl is added as an active agent and pH adjuster. The mass ratio of NH4Cl to In(NO3)3 is 1:1. The mixture is stirred at 900 rpm for 1.2 h. The container is then transferred from the 0°C ice-water mixture to a hydrothermal reactor with a filling ratio of 3.8:5. The mixture is hydrothermally reacted at 168°C and a constant pressure of 38 MPa for 3.6 h. After that, it is naturally cooled to 140°C and reacted for another 8 h.

[0044] Step 3: Centrifuge the product obtained in Step 2. Transfer the centrifuged solid to a freeze dryer and dry it at -40°C for 32 hours to obtain the indium oxide precursor. Place it in a vacuum chamber, evacuate it, and store it to preserve its activity.

[0045] Step 4: Sodium tungstate, oxalic acid, and ammonium chloride were added sequentially to deionized water. The molar ratio of sodium tungstate, oxalic acid, and ammonium chloride was 1.2:1.2:0.5, and the solid-liquid mass ratio was 0.30:15. The mixture was stirred at room temperature for 1.6 h at 1100 rpm. HCl with a concentration of 7 mol / L was added to the deionized water at a rate of 4 drops / s, so that the mass ratio of HCl to deionized water was 1:6. The mixture was stirred for 1.2 h. The product from Step 3 was added, and the temperature was increased by 2 °C for 60 min. The mixture was stirred for 2 h and then transferred to a hydrothermal reactor with a filling ratio of 3.8:5. The reactor was hydrothermally reacted at 180 °C and 38 MPa for 138 h. After natural cooling to room temperature, a yellow suspension was obtained. The suspension was centrifuged at 3500 rpm. The solid obtained by centrifugation was washed four times with ethanol. Finally, a composite material assembled from indium-depleted tungsten bronze phase blocks was obtained.

[0046] Example 3

[0047] A composite material assembled from indium-poor tungsten bronze phase mosaic blocks (In 0.02 The preparation method of WO3 / WO3 is as follows:

[0048] Step 1: Place a container of deionized water in a 70°C water bath and add sodium sulfate to the deionized water to make the concentration 7.2g / 100mL. Stir at 700rpm for 0.9h. Immediately place the container of deionized water in a 0°C ice-water mixture and reduce the stirring speed to 240rpm within 1s. Continue stirring for 13min to create a supersaturated sodium sulfate solution environment.

[0049] Step 2: In the supersaturated sodium sulfate solution obtained in Step 1, indium nitrate is added. The mass ratio of sodium sulfate to indium nitrate is 4.1:1. NH4Cl is added as an active agent and pH adjuster. The mass ratio of NH4Cl to In(NO3)3 is 1.5:1. The mixture is stirred at 1100 rpm for 0.8 h. The container is then transferred from the 0°C ice-water mixture to a hydrothermal reactor with a filling ratio of 4:5. The mixture is hydrothermally reacted at 174°C and a constant pressure of 36 MPa for 3.2 h. After that, it is naturally cooled to 150°C and reacted for another 7 h.

[0050] Step 3: Centrifuge the product obtained in Step 2. Transfer the centrifuged solid to a freeze dryer and dry it at -50°C for 26 hours to obtain the indium oxide precursor. Place it in a vacuum chamber, evacuate it, and store it to preserve its activity.

[0051] Step 4: Sodium tungstate, oxalic acid, and ammonium chloride were added sequentially to deionized water. The molar ratio of sodium tungstate, oxalic acid, and ammonium chloride was 0.5:1.1:0.3, and the solid-liquid mass ratio was 0.31:15. The mixture was stirred at room temperature for 1.2 h at 1200 rpm. 9 mol / L HCl was added to the deionized water at a rate of 5 drops / s, so that the mass ratio of HCl to deionized water was 1.2:6. The mixture was stirred for 1.4 h. The product from Step 3 was added, and the temperature was increased by 2 °C for 60 min. The mixture was stirred for 2 h and then transferred to a hydrothermal reactor with a filling ratio of 4:5. The reactor was hydrothermally reacted at 200 °C and 36 MPa for 9 h. After natural cooling to room temperature, a yellow suspension was obtained. The suspension was centrifuged at 4000 rpm. The solid obtained by centrifugation was washed four times with ethanol. Finally, the composite material assembled from indium-depleted tungsten bronze phase blocks was obtained.

[0052] Example 4

[0053] A composite material assembled from indium-poor tungsten bronze phase mosaic blocks (In 0.02 The preparation method of WO3 / WO3 is as follows:

[0054] Step 1: Place a container of deionized water in an 80°C water bath and add sodium sulfate to the deionized water to make the concentration 8.2g / 100mL. Stir at 800rpm for 0.5h. Immediately place the container of deionized water in a 0°C ice-water mixture and reduce the stirring speed to 300rpm within 1s. Continue stirring for 10min to create a supersaturated sodium sulfate solution environment.

[0055] Step 2: In the supersaturated sodium sulfate solution obtained in Step 1, indium nitrate is added. The mass ratio of sodium sulfate to indium nitrate is 4.2:1. At the same time, NH4Cl is added as an active agent and pH adjuster. The mass ratio of NH4Cl to In(NO3)3 is 2:1. The mixture is stirred at 1200 rpm for 0.5 h. The container is then transferred from the 0°C ice-water mixture to a hydrothermal reactor with a filling ratio of 4.2:5. The mixture is hydrothermally reacted at 180°C and a constant pressure of 35 MPa for 3 h. After that, it is naturally cooled to 160°C and reacted for another 6 h.

[0056] Step 3: Centrifuge the product obtained in Step 2. Transfer the centrifuged solid to a freeze dryer and dry it at -60°C for 20 hours to obtain the indium oxide precursor. Place it in a vacuum chamber, evacuate it, and store it to preserve its activity.

[0057] Step 4: Sodium tungstate, oxalic acid, and ammonium chloride were added sequentially to deionized water. The molar ratio of sodium tungstate, oxalic acid, and ammonium chloride was 0.8:1:0.4, and the solid-liquid mass ratio was 0.31:15. The mixture was stirred at room temperature for 1 hour at 1300 rpm. HCl with a concentration of 10 mol / L was added to the deionized water at a rate of 7 drops / s, so that the mass ratio of HCl to deionized water was 1.4:6. The mixture was stirred for 1.5 hours. The product from Step 3 was added, and the temperature was increased to 3°C for 70 minutes. The mixture was stirred for 3 hours and then transferred to a hydrothermal reactor with a filling ratio of 4.2:5. The reactor was hydrothermally reacted at 220°C and 35 MPa for 5 hours. After natural cooling to room temperature, a yellow suspension was obtained. The suspension was centrifuged at 4500 rpm. The solid obtained by centrifugation was washed five times with ethanol to finally obtain the composite material assembled from indium-depleted tungsten bronze phase blocks.

[0058] Performance testing:

[0059] To test the performance of the composite material assembled from indium-depleted tungsten bronze phase blocks prepared by the method of the present invention, the composite material assembled from indium-depleted tungsten bronze phase blocks prepared in Example 4 was first ground with ethanol for 30 minutes, then coated onto the surface of an alumina ceramic tube, and then welded to a base. The composite material was then placed in a WS-60A gas-sensitive element tester to test the sensitivity of 10 ppm acetone under different temperature conditions.

[0060] Test results are as follows Figure 6As shown, the horizontal axis represents the operating temperature, and the vertical axis represents the sensitivity. The sensitivity reaches 119 at an operating temperature of 100℃.

[0061] XRD patterns of composite materials assembled from indium-depleted tungsten bronze phase mosaic blocks, such as... Figure 1 As shown, In 0.02 The characteristic crystal plane (123) of WO3 has some of its three strong diffraction peaks overlapping with the three main peaks of monoclinic tungsten oxide. Figure 1 The XRD patterns of monoclinic tungsten oxide also show diffraction peaks on the (002), (020), and (200) crystal planes. Comparing these peaks with the XRD patterns of pure tungsten oxide, it can be determined that In₂ was successfully prepared. 0.02 WO3 / WO3 composite material.

[0062] Figure 2 The image shows the microstructure of a composite material assembled from indium-poor tungsten bronze phase mosaic blocks. In this structure, indium ions are distributed at two off-center locations within the tunnels, due to stereochemically active lone pairs (In...). 1+ 5s2) and W 6+ Coordination and W 6 + 6s² electron activation.

[0063] Figure 3 The image shows a partial SEM microstructure of the composite material assembled from indium-depleted tungsten bronze phase mosaic blocks. The hollow microspheres are self-assembled from numerous mosaic block-shaped strips. Individual hollow microspheres exhibit good dispersion within the indium-depleted tungsten bronze phase structure. The microspheres have a diameter of 2-3 μm and a thickness of 450 nm-520 nm. Each microsphere contains micropores with a diameter greater than 1 nm and less than or equal to 2 nm, mesopores with a diameter greater than 2 nm and less than or equal to 50 nm, and macropores with a diameter greater than 50 nm and less than or equal to 100 nm. The hollow structure is composed of mosaic block-shaped strips with a length of 50-250 nm, a height of 10-50 nm, and a width of 20-100 nm. The hollow structure allows for... Figure 5 The TEM microstructure of the composite material assembled from highly active, low-power indium-depleted tungsten bronze phase mosaic blocks is used for specific judgment.

[0064] Figure 4 The BJH adsorption and pore size distribution curves of the composite material assembled from indium-depleted tungsten bronze phase mosaic blocks are shown in the figure. The BJH adsorption curve of the formed composite material belongs to type III isotherms, indicating that the interaction between the adsorbent and adsorbate is quite weak. Higher relative pressure results in greater adsorption, demonstrating porous filling. The pore size distribution diagram shows that the pore size is concentrated between mesopores and micropores, which helps to improve the sensitivity to gases.

[0065] 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 composite material assembled from indium-depleted tungsten bronze phase mosaic blocks, characterized in that: The composite material assembled from indium-depleted tungsten bronze phase mosaic blocks is made of In 0.02 Composed of WO3 and WO3, the composite material assembled from indium-depleted tungsten bronze phase inlays contains numerous tunnels formed by the gaps between tungsten and oxygen atoms, with indium ions randomly distributed on both sides of the center of the tunnels. The structure of the composite material assembled from indium-depleted tungsten bronze phase inlays consists of countless hollow spheres. The hollow spheres of a single indium-depleted tungsten bronze phase structure are well dispersed, with a diameter of 2-3 μm and a thickness of 450 nm-520 nm. The microspheres contain micropores with a diameter greater than 1 nm and less than or equal to 2 nm, mesopores with a diameter greater than 2 nm and less than or equal to 50 nm, and macropores with a diameter greater than 50 nm and less than or equal to 100 nm. The hollow spheres of a single indium-depleted tungsten bronze phase structure are hollow sphere structures assembled from inlaid block-shaped strips with a length of 50-250 nm, a height of 10-50 nm, and a width of 20-100 nm.

2. A method for preparing a composite material assembled from indium-depleted tungsten bronze phase inserts as described in claim 1, characterized in that: The steps are as follows: Step 1: Place a container filled with deionized water in a water bath at 50-80℃, add sodium sulfate to the deionized water to make the concentration 5.8-8.2g / 100mL, stir at 500-800rpm for 0.5-1.5h, then quickly place the container filled with deionized water in a 0℃ ice-water mixture and reduce the stirring speed to 100-300rpm within 1s, and continue stirring for 10-20min to create a supersaturated sodium sulfate solution environment; Step 2: In the supersaturated sodium sulfate solution obtained in Step 1, indium nitrate is added. The mass ratio of sodium sulfate to indium nitrate is (3.8-4.2):

1. At the same time, NH4Cl is added as an active agent and pH adjuster. The mass ratio of NH4Cl to In(NO3)3 is (0.5-2):

1. The mixture is stirred at 700-1200 rpm for 0.5-1.5 hours. The container is then transferred from the 0°C ice-water mixture to a hydrothermal reactor with a filling ratio of (3.5-4.2):

5. The mixture is then hydrothermally reacted at 160-180°C and a constant pressure of 35-40 MPa for 3-4 hours. After that, the mixture is naturally cooled to 130-160°C and reacted for another 6-10 hours. Step 3: Centrifuge the product obtained in Step 2. Transfer the centrifuged solid to a freeze dryer and dry it at -30 to -60°C for 20-40 hours to obtain the indium oxide precursor. Place it in a vacuum chamber, evacuate it, and store it to preserve its activity. Step 4: Add sodium tungstate, oxalic acid, and ammonium chloride sequentially to deionized water. The molar ratio of sodium tungstate, oxalic acid, and ammonium chloride is (0.3-1.2):(1-1.2):(0.1-0.5), and the solid-liquid mass ratio is (0.30-0.31):

15. Stir at room temperature for 1-2 hours at 1000-1300 rpm. Add 6-10 mol / L HCl to the deionized water at 2-7 drops / s, making the mass ratio of HCl to deionized water (0.8-1.4):6). Continue stirring for 1 hour. -1.5h, add the product from step 3, and heat at 1-3℃ for 50-70min, stirring continuously for 1-3h. Transfer to a hydrothermal reactor with a filling ratio of (3.5-4.2):5, and hydrothermally react at 150-220℃ and 35-40MPa for 5-18h. After natural cooling to room temperature, a yellow suspension mixture is obtained, which is then centrifuged at 3000-4500rpm. The solid obtained by centrifugation is washed with ethanol 3-5 times to finally obtain the composite material assembled from indium-depleted tungsten bronze phase blocks.

Images