A resistive acetone sensor based on metal indium / mesoporous indium trioxide composite material, preparation method and application thereof

Abstract

A resistive acetone sensor based on indium / mesoporous indium oxide composite material, a preparation method thereof and an application thereof in detecting acetone, belonging to the technical field of gas sensing. The sensor has a tubular structure and is composed of an Al2O3 ceramic tube substrate, two parallel and discrete annular Au electrodes coated on the outer surface of the Al2O3 ceramic tube substrate, a metal indium / mesoporous indium oxide composite material gas-sensitive thin film coated on the outer surface of the Al2O3 ceramic tube and the annular Au electrodes, and a nickel-chromium alloy heating coil passing through the Al2O3 ceramic tube. In the present invention, three structure regulation strategies of mesoporous structure, metal / semiconductor heterostructure and oxygen vacancy are simultaneously introduced into the sensitive material, and the sensitive performance of the device is improved by using the synergistic effect of the three; the present invention adopts an in-situ high-temperature reduction method of semiconductor oxides to prepare a heterostructure of metal / semiconductor oxides, which has the advantages of close contact of the interface structure and good stability of metal particles.

Description

Technical Field

[0001] The invention belongs to the technical field of gas sensing, and in particular relates to a resistance-type acetone sensor based on a metal indium / mesoporous indium trioxide composite material, a preparation method and application of the sensor in detecting acetone. Background Art

[0002] Acetone is a commonly used chemical reagent, which is widely used as a solvent and reactant in the fields of organic synthesis, catalytic chemical industry, etc. Acetone has the characteristics of low boiling point, high volatility, flammability and explosiveness, and is a typical volatile organic compound. Acetone gas can cause serious damage to the human skin, nervous system, respiratory system, etc., and become a toxic and harmful pollutant gas in the atmospheric environment. In addition, acetone is also one of the exhaled breath markers of diabetes. By monitoring the concentration of acetone gas in human exhaled breath, non-invasive diagnosis of diabetes can be achieved. Therefore, accurate and rapid detection of acetone has important practical value in environmental monitoring and biomedicine.

[0003] At present, researchers have developed a variety of analytical detection technologies for the detection of acetone. Among them, gas chromatography technology is a mature and high-precision analytical method that can detect acetone with high sensitivity and selectivity. However, gas chromatography technology relies on bulky and expensive instruments, and in particular, it is unable to detect acetone quickly and on-site. Therefore, the development of miniaturized and portable detection instruments to achieve rapid detection of acetone is a research problem that urgently needs to be solved.

[0004] In recent years, resistive gas sensors based on semiconductor oxides have developed rapidly, providing a new idea for the development of miniaturized acetone gas detection instruments. In particular, resistive gas sensors have the advantages of high sensitivity, low cost, low power consumption, and small size, making them an ideal acetone detection instrument. At present, semiconductor oxides such as tin dioxide, indium trioxide, and zinc oxide have been used to detect acetone. However, the detection performance of these traditional semiconductor oxide materials for acetone is generally poor and cannot be used for commercial promotion and use. Subsequently, researchers have developed a series of new methods to improve the sensitivity of semiconductor oxide acetone sensors, such as constructing heterostructures, constructing porous structures, and increasing oxygen vacancy concentrations. Although these methods have improved the sensitivity of the device to a certain extent. However, further improving the detection performance of acetone sensors is still the primary problem that needs to be solved urgently. Summary of the invention

[0005] The invention aims to provide a resistive acetone sensor based on a metal indium / mesoporous indium trioxide composite material, a preparation method and application thereof in detecting acetone.

[0006] The resistive acetone sensor based on the metal indium / mesoporous indium trioxide composite material of the present invention is a tubular structure. 2 O 3 Ceramic tube substrate, coated on Al 2 O 3 Two parallel and separate annular Au electrodes on the outer surface of the ceramic tube substrate, coated on Al 2 O 3 The gas sensitive film on the outer surface of the ceramic tube and the annular Au electrode passes through the Al 2 O 3 The ceramic tube is composed of a nickel-chromium alloy heating coil; the characteristic is that the material of the gas sensitive film is a metal indium / mesoporous indium trioxide composite material, which is prepared by the following steps:

[0007] (1) 1.0-3.0 g of triblock copolymer P123 (EO 20 PO 70 EO 20 , molecular weight 5800, Adrich Chemical Reagent Company) was added to 50-70 mL of water, and then 6.0-8.0 g of concentrated hydrochloric acid and 1.0-3.0 g of n-butanol were added to the above solution in sequence, and stirred at room temperature for 1-2 hours. Under the action of concentrated hydrochloric acid and n-butanol, P123 was dissolved and rod-shaped micelles were formed to obtain a mixed solution containing P123 micelles, hydrochloric acid and n-butanol;

[0008] (2) adding 3.0-5.0 g of tetraethyl orthosilicate to the mixed solution containing P123 micelles, hydrochloric acid and n-butanol obtained in step (1), stirring at 35-45° C. for 18-30 h, then charging the mixed solution into a reaction kettle, and hydrothermally treating at 100-120° C. for 24-36 h; the tetraethyl orthosilicate is hydrolyzed to generate silica, and the generated silica is coated on the surface of the P123 micelles; the obtained reaction solution is centrifuged, washed with ethanol, and dried to obtain a mesoporous silica material containing P123;

[0009] (3) calcining the mesoporous silica material containing P123 obtained in step (2) at 500-600° C. for 2-4 h, wherein P123 is decomposed into carbon dioxide and water under high temperature conditions to obtain a mesoporous silica material;

[0010] (4) adding the mesoporous silica material obtained in step (3) to 8-10 mL of ethanol, then adding 0.5-0.8 g of indium nitrate to the mixed solution, and stirring at room temperature for 2-3 h; drying the resulting mixture at 40-50° C. for 24-36 h, dispersing the indium nitrate into the pores of the mesoporous silica, and obtaining a mesoporous silica material filled with indium nitrate;

[0011] (5) calcining the mesoporous silica material filled with indium nitrate obtained in step (4) at 260 to 280° C. for 2 to 4 hours, wherein during the calcination process, the indium nitrate is converted into indium trioxide to obtain a mesoporous silica material filled with indium trioxide;

[0012] (6) adding the indium trioxide-filled mesoporous silica material obtained in step (5) to 8-10 mL of ethanol, then adding 0.3-0.5 g of indium nitrate to the mixed solution, and stirring at room temperature for 2-3 h; drying the resulting mixture at 40-50° C. for 24-36 h, dispersing the indium nitrate into the pores of the mesoporous silica material filled with indium trioxide, and obtaining a mesoporous silica material filled with indium nitrate and indium trioxide;

[0013] (7) calcining the mesoporous silica material filled with indium nitrate and indium trioxide obtained in step (6) at 500 to 600° C. for 2 to 4 hours, wherein during the calcination process, the indium nitrate is converted into indium trioxide to obtain a mesoporous silica material filled with indium trioxide;

[0014] (8) adding the indium trioxide-filled mesoporous silica material obtained in step (7) to 20-40 mL of a sodium hydroxide solution having a concentration of 1-3 M, and stirring at 60-80° C. for 2-4 h; the sodium hydroxide dissolves the silica into sodium silicate soluble in water, and the obtained solution is centrifuged, washed with ethanol, and dried to obtain a mesoporous indium trioxide material;

[0015] (9) The mesoporous indium trioxide material obtained in step (8) is placed in a mixed gas protection of hydrogen and nitrogen, wherein the volume fraction of hydrogen in the mixed gas is 5% to 10%, and calcined at 300 to 400° C. for 2 to 4 hours, so that a portion of the indium trioxide is reduced to metallic indium, and a portion of the lattice oxygen in the indium trioxide is oxidized to form oxygen vacancies, thereby obtaining a metallic indium / mesoporous indium trioxide composite material.

[0016] Al 2 O 3 The length of the ceramic tube is 3-5mm, the outer diameter is 1.1-1.3mm, and the inner diameter is 0.7-0.9mm; the nickel-chromium alloy heating coil provides the working temperature for the sensor, and the resistance of the heating coil is 30-40Ω; the width of the ring-shaped Au electrode is 0.7-0.9mm, and the distance between the two electrodes is 1.7-1.9mm; the thickness of the gas sensitive film is 180-220μm; before and after the gas sensitive film contacts the gas to be measured, its resistance will change. By measuring the change in the resistance of the two ring-shaped Au electrodes, the sensitivity of the sensor can be obtained. The sensitivity is calculated by dividing the resistance value between the ring-shaped gold electrodes in the air by its resistance value in the target gas.

[0017] The method for preparing a resistive acetone sensor based on a metal indium / mesoporous indium trioxide composite material of the present invention comprises the following steps:

[0018] (1) mixing the metal indium / mesoporous indium trioxide composite material with deionized water in a mass ratio of 3 to 5:1 and grinding the mixture into a paste slurry; coating the paste on an Al substrate having two parallel and separate annular Au electrodes on its outer surface; 2 O 3 Ceramic tube surface;

[0019] (2) The device obtained in step (1) is baked under an infrared lamp for 20 to 40 minutes. After the sensitive material is dried, a nickel-chromium alloy heating coil with a resistance value of 30 to 40 Ω is passed through the Al 2 O 3 The ceramic tube is used as a heating wire and is welded and packaged as a side-heated gas sensor.

[0020] (3) The device obtained in step (2) is aged at 280-320° C. for 8-12 h, thereby obtaining a resistive acetone sensor based on a metal indium / mesoporous indium trioxide composite material.

[0021] The advantages of the present invention are:

[0022] 1) The sensitive material in the present invention has a porous structure, such as Figure 1 As shown, the prepared material is composed of a large number of nanoparticles. The large number of gaps between the particles are conducive to the diffusion and transmission of gas molecules, thereby improving the sensitivity of the acetone sensor.

[0023] 2) The sensitive material in the present invention contains two components: metallic indium and indium trioxide. Figure 2 The characteristic diffraction peaks of metallic indium and indium trioxide exist simultaneously. Figure 3 The In3d peaks belonging to zero-valent indium and trivalent indium can also prove that there are two structures at the same time. Metallic indium and indium trioxide can form a heterostructure between metal and semiconductor, which can improve the adsorption capacity of sensitive materials to oxygen molecules, thereby improving the sensitivity of acetone sensors.

[0024] 3) The sensitive material in the present invention has abundant oxygen vacancies. Figure 4 The presence of a strong peak in the O1s spectrum attributable to oxygen vacancies shows that it is mainly formed by hydrogen reducing the oxygen ions in the indium trioxide crystal structure under high temperature conditions. The increase in oxygen vacancies can not only improve the adsorption capacity of sensitive materials for oxygen molecules, but also adjust the energy band structure of indium trioxide, thereby improving the acetone sensitivity.

[0025] 4) The present invention simultaneously introduces three structural control strategies, namely, mesoporous structure, metal / semiconductor heterostructure and oxygen vacancy, into the sensitive material, and utilizes the synergistic effect of the three to enhance the sensitivity of the device.

[0026] 5) The present invention adopts the method of in-situ high-temperature reduction of semiconductor oxide to prepare the metal / semiconductor oxide heterostructure, which has the advantages of close contact of interface structure and good stability of metal particles. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a scanning electron microscope photo of the metal indium / mesoporous indium trioxide composite material;

[0028] Figure 2 It is the X-ray diffraction pattern of metal indium / mesoporous indium trioxide composite material;

[0029] Figure 3 It is the In 3d spectrum peak curve of metal indium / mesoporous indium trioxide composite material;

[0030] Figure 4 It is the O1s spectrum peak curve of metal indium / mesoporous indium trioxide composite material;

[0031] Figure 5 is a dynamic response recovery curve of the acetone sensor based on the metal indium / mesoporous indium trioxide composite material in Example 1 to 100 ppm acetone at 200°C;

[0032] Figure 6 is a dynamic response recovery curve of the acetone sensor based on the metal indium / mesoporous indium trioxide composite material in Example 1 to different concentrations of acetone at 200°C;

[0033] Figure 7 is a dynamic response recovery curve of the acetone sensor based on the metal indium / mesoporous indium trioxide composite material in Example 1 to 100 ppm acetone at 250° C.;

[0034] Figure 8 is a dynamic response recovery curve of the acetone sensor based on the metal indium / mesoporous indium trioxide composite material in Example 2 to 100 ppm acetone at 300° C.;

[0035] Fig. 9 is a dynamic response recovery curve of the acetone sensor based on the metal indium / mesoporous indium trioxide composite material in Example 3 to 100 ppm acetone at 350° C.;

[0036] Fig.10 This is the dynamic response recovery curve of the acetone sensor based on the metal indium / mesoporous indium trioxide composite material in Example 4 to 100 ppm acetone at 400°C. DETAILED DESCRIPTION

[0037] The present invention is further described below with reference to the accompanying drawings and embodiments.

[0038] Example 1

[0039] (1) 1.0 g of triblock copolymer P123 (EO 20 PO 70 EO 20 , molecular weight 5800, Adrich Chemical Reagent Company) was added to 50mL of water; then 6.0g of hydrochloric acid and 3.0

[0040] g n-butanol, stirred at room temperature for 1 h, under the action of hydrochloric acid and n-butanol, P123 was dissolved and rod-shaped micelles were formed, and a mixed solution of P123 micelles, hydrochloric acid and n-butanol was obtained;

[0041] (2) adding 3.0 g of tetraethyl orthosilicate to the mixed solution containing P123 micelles, hydrochloric acid and n-butanol obtained in step (1), stirring at 35° C. for 18 h, then charging the mixed solution into a reactor, and hydrothermally treating at 120° C. for 36 h; the tetraethyl orthosilicate is hydrolyzed to generate silica, and the generated silica is coated on the surface of the P123 micelles; the obtained reaction solution is centrifuged, washed with ethanol, and dried to obtain a mesoporous silica material containing P123;

[0042] (3) calcining the mesoporous silica material containing P123 obtained in step (2) at 600° C. for 4 h.

[0043] P123 decomposes into carbon dioxide and water under high temperature conditions to obtain mesoporous silica material;

[0044] (4) adding the mesoporous silica material obtained in step (3) to 8 mL of ethanol, then adding 0.8 g of indium nitrate to the mixed solution, and stirring at room temperature for 2 h; drying the resulting mixture at 50° C. for 24 h, dispersing the indium nitrate into the pores of the mesoporous silica, and obtaining an indium nitrate-filled mesoporous silica material;

[0045] (5) calcining the indium nitrate-filled mesoporous silica material obtained in step (4) at 260° C. for 4 h. During the calcination process, the indium nitrate is converted into indium trioxide to obtain an indium trioxide-filled mesoporous silica material;

[0046] (6) adding the indium trioxide-filled mesoporous silica material obtained in step (5) to 10 mL of ethanol, then adding 0.3 g of indium nitrate to the mixed solution, and stirring at room temperature for 2 h; drying the resulting mixture at 40° C. for 24 h, dispersing the indium nitrate into the pores of the indium trioxide-filled mesoporous silica material, and obtaining a mesoporous silica material co-filled with indium nitrate and indium trioxide;

[0047] (7) filling the mesoporous silica material with the indium nitrate and indium trioxide obtained in step (6), and calcining at 500° C. for 2 h. During the calcination process, the indium nitrate is converted into indium trioxide to obtain the indium trioxide-filled mesoporous silica material;

[0048] (8) Add the indium trioxide-filled mesoporous silica material obtained in step (7) to a solution having a concentration of 40

[0049] mL of 1M sodium hydroxide solution, stirred at 60°C for 2h; sodium hydroxide dissolved silicon dioxide into sodium silicate soluble in water, and the obtained solution was centrifuged, washed with ethanol, and dried to obtain a mesoporous indium trioxide material;

[0050] (9) placing the mesoporous indium trioxide material obtained in step (8) in a hydrogen and nitrogen mixed gas protection, wherein the volume fraction of hydrogen in the mixed gas is 5%, and calcining at 300° C. for 2 h, a portion of the indium trioxide is reduced to metallic indium, and a portion of the lattice oxygen in the indium trioxide is oxidized to form oxygen vacancies, thereby obtaining a metallic indium / mesoporous indium trioxide composite material, the mass of the product being 1.0 g;

[0051] (10) The metal indium / mesoporous indium trioxide composite material prepared in step (9) is mixed with deionized water at a mass ratio of 5:1, and ground into a paste slurry, and the slurry is applied to an Al2O3 substrate having two parallel and separate annular Au electrodes on its outer surface. 2 O 3 The ceramic tube surface was baked under infrared light for 20 minutes to obtain a sensitive film based on metal indium / mesoporous indium trioxide composite material on the ceramic tube surface. The thickness of the sensitive film was 220 μm. Then a nickel-chromium alloy heating coil with a resistance value of 30 Ω was passed through the Al 2 O 3 The ceramic tube is used as the heating wire and finally welded and packaged as a side-heated gas sensor.

[0052] Al 2 O 3 The length of the ceramic tube is 5 mm, the outer diameter is 1.1 mm, and the inner diameter is 0.7 mm; the width of the annular Au electrode is 0.9 mm, and the distance between the two electrodes is 1.9 mm;

[0053] (11) The acetone gas sensor based on the metal indium / mesoporous indium trioxide composite material obtained in step (10) is aged at 280° C. for 12 hours to complete the aging treatment of the gas sensor, thereby obtaining a resistive acetone sensor based on the metal indium / mesoporous indium trioxide composite material.

[0054] Example 2

[0055] (1) 1.0 g of triblock copolymer P123 (EO 20 PO 70 EO 20 , molecular weight 5800, Adrich Chemical Reagent Company) was added to 50mL of water; then 7.0g of hydrochloric acid and 3.0

[0056] g n-butanol, stirred at room temperature for 1 h, under the action of hydrochloric acid and n-butanol, P123 was dissolved and rod-shaped micelles were formed, and a mixed solution of P123 micelles, hydrochloric acid and n-butanol was obtained;

[0057] (2) adding 4.0 g of tetraethyl orthosilicate to the mixed solution containing P123 micelles, hydrochloric acid and n-butanol obtained in step (1), stirring at 40° C. for 18 h, then charging the mixed solution into a reactor, and hydrothermally treating at 120° C. for 24 h; the tetraethyl orthosilicate is hydrolyzed to generate silica, and the generated silica is coated on the surface of the P123 micelles; the obtained reaction solution is centrifuged, washed with ethanol, and dried to obtain a mesoporous silica material containing P123;

[0058] (3) calcining the mesoporous silica material containing P123 obtained in step (2) at 600° C. for 3 h, wherein P123 is decomposed into carbon dioxide and water under high temperature conditions to obtain a mesoporous silica material;

[0059] (4) adding the mesoporous silica material obtained in step (3) to 8 mL of ethanol, then adding 0.7 g of indium nitrate to the mixed solution, and stirring at room temperature for 2 h; drying the resulting mixture at 50° C. for 36 h, dispersing the indium nitrate into the pores of the mesoporous silica, and obtaining an indium nitrate-filled mesoporous silica material;

[0060] (5) calcining the indium nitrate-filled mesoporous silica material obtained in step (4) at 260° C. for 4 h. During the calcination process, the indium nitrate is converted into indium trioxide to obtain an indium trioxide-filled mesoporous silica material;

[0061] (6) adding the indium trioxide-filled mesoporous silica material obtained in step (5) to 10 mL of ethanol, then adding 0.4 g of indium nitrate to the mixed solution, and stirring at room temperature for 3 h; drying the resulting mixture at 40° C. for 36 h, dispersing the indium nitrate into the pores of the indium trioxide-filled mesoporous silica material, and obtaining a mesoporous silica material co-filled with indium nitrate and indium trioxide;

[0062] (7) filling the mesoporous silica material with the indium nitrate and indium trioxide obtained in step (6), and calcining at 500° C. for 3 h. During the calcination process, the indium nitrate is converted into indium trioxide to obtain the indium trioxide-filled mesoporous silica material;

[0063] (8) Add the indium trioxide-filled mesoporous silica material obtained in step (7) to a solution having a concentration of 40

[0064] mL of 2M sodium hydroxide solution, stirred at 70°C for 3h; sodium hydroxide dissolved silicon dioxide into sodium silicate soluble in water, and the obtained solution was centrifuged, washed with ethanol, and dried to obtain a mesoporous indium trioxide material;

[0065] (9) placing the mesoporous indium trioxide material obtained in step (8) in a hydrogen and nitrogen mixed gas protection, wherein the volume fraction of hydrogen in the mixed gas is 10%, and calcining at 300° C. for 3 h, a portion of the indium trioxide is reduced to metallic indium, and a portion of the lattice oxygen in the indium trioxide is oxidized to form oxygen vacancies, thereby obtaining a metallic indium / mesoporous indium trioxide composite material, the mass of the product being 0.9 g;

[0066] (10) The metal indium / mesoporous indium trioxide composite material prepared in step (9) is mixed with deionized water in a mass ratio of 4:1, and ground into a paste slurry, and the slurry is applied to an Al2O3 substrate having two parallel, annular and separate gold electrodes on its outer surface. 2 O 3 The ceramic tube surface was baked under infrared light for 20 minutes to obtain a sensitive film based on surface functionalized zinc oxide on the ceramic tube surface. The thickness of the sensitive film was 220 μm. Then a nickel-chromium alloy heating coil with a resistance value of 30 Ω was passed through the Al 2 O 3 The ceramic tube is used as the heating wire, and finally welded and packaged as a side-heated gas sensor; Al 2 O 3 The length of the ceramic tube is 5 mm, the outer diameter is 1.1 mm, and the inner diameter is 0.7 mm; the width of the annular Au electrode is 0.9 mm, and the distance between the two electrodes is 1.9 mm;

[0067] (11) The acetone gas sensor based on the metal indium / mesoporous indium trioxide composite material obtained in step (10) is aged at 280° C. for 8 hours to complete the aging treatment of the gas sensor, thereby obtaining a resistive acetone sensor based on the metal indium / mesoporous indium trioxide composite material.

[0068] Example 3

[0069] (1) 2.0 g of triblock copolymer P123 (EO 20 PO 70 EO 20 , molecular weight 5800, Adrich Chemical Reagent Company) was added to 60mL of water; then 8.0g of hydrochloric acid and 2.0

[0070] g n-butanol, stirred at room temperature for 1 h, under the action of hydrochloric acid and n-butanol, P123 was dissolved and rod-shaped micelles were formed, and a mixed solution of P123 micelles, hydrochloric acid and n-butanol was obtained;

[0071] (2) adding 5.0 g of tetraethyl orthosilicate to the mixed solution containing P123 micelles, hydrochloric acid and n-butanol obtained in step (1), stirring at 45° C. for 18 h, then charging the mixed solution into a reactor, and hydrothermally treating at 110° C. for 36 h; the tetraethyl orthosilicate is hydrolyzed to generate silica, and the generated silica is coated on the surface of the P123 micelles; the obtained reaction solution is centrifuged, washed with ethanol, and dried to obtain a mesoporous silica material containing P123;

[0072] (3) calcining the mesoporous silica material containing P123 obtained in step (2) at 600° C. for 2 h, wherein P123 is decomposed into carbon dioxide and water under high temperature conditions to obtain a mesoporous silica material;

[0073] (4) adding the mesoporous silica material obtained in step (3) to 9 mL of ethanol, then adding 0.7 g of indium nitrate to the mixed solution, and stirring at room temperature for 2 h; drying the resulting mixture at 50° C. for 24 h, dispersing the indium nitrate into the pores of the mesoporous silica, and obtaining an indium nitrate-filled mesoporous silica material;

[0074] (5) calcining the indium nitrate-filled mesoporous silica material obtained in step (4) at 270° C. for 3 h. During the calcination process, the indium nitrate is converted into indium trioxide to obtain an indium trioxide-filled mesoporous silica material;

[0075] (6) adding the indium trioxide-filled mesoporous silica material obtained in step (5) to 9 mL of ethanol, then adding 0.5 g of indium nitrate to the mixed solution, and stirring at room temperature for 2 h; drying the resulting mixture at 45° C. for 24 h, and dispersing the indium nitrate into the pores of the indium trioxide-filled mesoporous silica material, to obtain a mesoporous silica material co-filled with indium nitrate and indium trioxide;

[0076] (7) filling the mesoporous silica material with the indium nitrate and indium trioxide obtained in step (6), and calcining at 500° C. for 4 h. During the calcination process, the indium nitrate is converted into indium trioxide to obtain the indium trioxide-filled mesoporous silica material;

[0077] (8) Add the indium trioxide-filled mesoporous silica material obtained in step (7) to a solution having a concentration of 30

[0078] mL of 3M sodium hydroxide solution, stirred at 80°C for 4h; sodium hydroxide dissolved silicon dioxide into sodium silicate soluble in water, and the obtained solution was centrifuged, washed with ethanol, and dried to obtain a mesoporous indium trioxide material;

[0079] (9) placing the mesoporous indium trioxide material obtained in step (8) in a hydrogen and nitrogen mixed gas protection, wherein the volume fraction of hydrogen in the mixed gas is 5%, and calcining at 300° C. for 4 h, a portion of the indium trioxide is reduced to metallic indium, and a portion of the lattice oxygen in the indium trioxide is oxidized to form oxygen vacancies, thereby obtaining a metallic indium / mesoporous indium trioxide composite material, the mass of the product being 1.1 g;

[0080] (10) The metal indium / mesoporous indium trioxide composite material prepared in step (9) is mixed with deionized water in a mass ratio of 3:1, and ground into a paste slurry, and the slurry is applied to an Al2O3 substrate having two parallel, annular and separate gold electrodes on its outer surface. 2 O 3 The ceramic tube surface was baked under infrared light for 30 minutes to obtain a sensitive film based on surface functionalized zinc oxide on the ceramic tube surface. The thickness of the sensitive film was 200 μm. Then a nickel-chromium alloy heating coil with a resistance value of 30 Ω was passed through the Al 2 O 3 The ceramic tube is used as the heating wire, and finally welded and packaged as a side-heated gas sensor; Al 2 O 3 The length of the ceramic tube is 4 mm, the outer diameter is 1.1 mm, and the inner diameter is 0.7 mm; the width of the annular Au electrode is 0.9 mm, and the distance between the two electrodes is 1.9 mm;

[0081] (11) The acetone gas sensor based on the metal indium / mesoporous indium trioxide composite material obtained in step (10) is aged at 300° C. for 12 hours to complete the aging treatment of the gas sensor, thereby obtaining a resistive acetone sensor based on the metal indium / mesoporous indium trioxide composite material.

[0082] Example 4

[0083] (1) 2.0 g of triblock copolymer P123 (EO 20 PO 70 EO 20 , molecular weight 5800, Adrich Chemical Reagent Company) was added to 60mL of water; then 6.0g of hydrochloric acid and 2.0

[0084] g n-butanol, stirred at room temperature for 2 h, under the action of hydrochloric acid and n-butanol, P123 was dissolved and rod-shaped micelles were formed, and a mixed solution of P123 micelles, hydrochloric acid and n-butanol was obtained;

[0085] (2) adding 3.0 g of tetraethyl orthosilicate to the mixed solution containing P123 micelles, hydrochloric acid and n-butanol obtained in step (1), stirring at 35° C. for 30 h, then charging the mixed solution into a reactor, and hydrothermally treating at 110° C. for 24 h; the tetraethyl orthosilicate is hydrolyzed to generate silica, and the generated silica is coated on the surface of the P123 micelles; the obtained reaction solution is centrifuged, washed with ethanol, and dried to obtain a mesoporous silica material containing P123;

[0086] (3) calcining the mesoporous silica material containing P123 obtained in step (2) at 500° C. for 4 h, wherein P123 is decomposed into carbon dioxide and water under high temperature conditions to obtain a mesoporous silica material;

[0087] (4) adding the mesoporous silica material obtained in step (3) to 9 mL of ethanol, then adding 0.6 g of indium nitrate to the mixed solution, and stirring at room temperature for 3 h; drying the resulting mixture at 40° C. for 36 h, dispersing the indium nitrate into the pores of the mesoporous silica, and obtaining an indium nitrate-filled mesoporous silica material;

[0088] (5) calcining the indium nitrate-filled mesoporous silica material obtained in step (4) at 270° C. for 3 h. During the calcination process, the indium nitrate is converted into indium trioxide to obtain an indium trioxide-filled mesoporous silica material;

[0089] (6) adding the indium trioxide-filled mesoporous silica material obtained in step (5) to 9 mL of ethanol, then adding 0.5 g of indium nitrate to the mixed solution, and stirring at room temperature for 3 h; drying the resulting mixture at 45° C. for 36 h, dispersing the indium nitrate into the pores of the indium trioxide-filled mesoporous silica material, and obtaining a mesoporous silica material co-filled with indium nitrate and indium trioxide;

[0090] (7) filling the mesoporous silica material with the indium nitrate and indium trioxide obtained in step (6), and calcining at 600° C. for 4 h. During the calcination process, the indium nitrate is converted into indium trioxide to obtain the indium trioxide-filled mesoporous silica material;

[0091] (8) Add the indium trioxide-filled mesoporous silica material obtained in step (7) to a solution having a concentration of 30

[0092] mL, 1M sodium hydroxide solution, stirred at 60°C for 4h; sodium hydroxide dissolved silicon dioxide into sodium silicate soluble in water, and the obtained solution was centrifuged, washed with ethanol, and dried to obtain mesoporous indium trioxide material;

[0093] (9) placing the mesoporous indium trioxide material obtained in step (8) in a hydrogen and nitrogen mixed gas protection, wherein the volume fraction of hydrogen in the mixed gas is 10%, and calcining at 400° C. for 2 h, a portion of the indium trioxide is reduced to metallic indium, and a portion of the lattice oxygen in the indium trioxide is oxidized to form oxygen vacancies, thereby obtaining a metallic indium / mesoporous indium trioxide composite material, the mass of the product being 1.0 g;

[0094] (10) The metal indium / mesoporous indium trioxide composite material prepared in step (9) is mixed with deionized water at a mass ratio of 5:1, and ground into a paste slurry, and the slurry is applied to an Al2O3 substrate having two parallel, annular and separate gold electrodes on its outer surface. 2 O 3 The ceramic tube surface was baked under an infrared lamp for 30 minutes to obtain a sensitive film based on surface functionalized zinc oxide on the ceramic tube surface. The thickness of the sensitive film was 200 μm. Then a nickel-chromium alloy heating coil with a resistance value of 40 Ω was passed through the Al 2 O 3 The ceramic tube is used as the heating wire, and finally welded and packaged as a side-heated gas sensor; Al 2 O 3 The length of the ceramic tube is 4 mm, the outer diameter is 1.3 mm, and the inner diameter is 0.9 mm; the width of the annular Au electrode is 0.7 mm, and the distance between the two electrodes is 1.7 mm;

[0095] (11) The acetone gas sensor based on the metal indium / mesoporous indium trioxide composite material obtained in step (10) is aged at 300° C. for 8 hours to complete the aging treatment of the gas sensor, thereby obtaining a resistive acetone sensor based on the metal indium / mesoporous indium trioxide composite material.

[0096] Example 5

[0097] (1) 3.0 g of triblock copolymer P123 (EO 20 PO 70 EO 20 , molecular weight 5800, Adrich Chemical Reagent Company) was added to 70mL of water; then 7.0g of hydrochloric acid and 1.0

[0098] g n-butanol, stirred at room temperature for 2 h, under the action of hydrochloric acid and n-butanol, P123 was dissolved and rod-shaped micelles were formed, and a mixed solution of P123 micelles, hydrochloric acid and n-butanol was obtained;

[0099] (2) adding 4.0 g of tetraethyl orthosilicate to the mixed solution containing P123 micelles, hydrochloric acid and n-butanol obtained in step (1), stirring at 40° C. for 30 h, then charging the mixed solution into a reactor, and hydrothermally treating at 100° C. for 36 h; tetraethyl orthosilicate is hydrolyzed to generate silica, and the generated silica is coated on the surface of the P123 micelles; the obtained reaction solution is centrifuged, washed with ethanol, and dried to obtain a mesoporous silica material containing P123;

[0100] (3) calcining the mesoporous silica material containing P123 obtained in step (2) at 500° C. for 3 h, wherein P123 is decomposed into carbon dioxide and water under high temperature conditions to obtain a mesoporous silica material;

[0101] (4) adding the mesoporous silica material obtained in step (3) to 10 mL of ethanol, then adding 0.6 g of indium nitrate to the mixed solution, and stirring at room temperature for 3 h; drying the resulting mixture at 40° C. for 24 h, dispersing the indium nitrate into the pores of the mesoporous silica, and obtaining an indium nitrate-filled mesoporous silica material;

[0102] (5) calcining the indium nitrate-filled mesoporous silica material obtained in step (4) at 280° C. for 2 h. During the calcination process, the indium nitrate is converted into indium trioxide to obtain an indium trioxide-filled mesoporous silica material;

[0103] (6) adding the indium trioxide-filled mesoporous silica material obtained in step (5) to 8 mL of ethanol, then adding 0.4 g of indium nitrate to the mixed solution, and stirring at room temperature for 2 h; drying the resulting mixture at 50° C. for 24 h, dispersing the indium nitrate into the pores of the indium trioxide-filled mesoporous silica material, and obtaining a mesoporous silica material co-filled with indium nitrate and indium trioxide;

[0104] (7) filling the mesoporous silica material with the indium nitrate and indium trioxide obtained in step (6), and calcining at 600° C. for 3 h. During the calcination process, the indium nitrate is converted into indium trioxide to obtain the indium trioxide-filled mesoporous silica material;

[0105] (8) Add the indium trioxide-filled mesoporous silica material obtained in step (7) to a solution having a concentration of 20

[0106] mL of 2M sodium hydroxide solution, stirred at 70°C for 3h; sodium hydroxide dissolved silicon dioxide into sodium silicate soluble in water, and the obtained solution was centrifuged, washed with ethanol, and dried to obtain a mesoporous indium trioxide material;

[0107] (9) placing the mesoporous indium trioxide material obtained in step (8) in a hydrogen and nitrogen mixed gas protection, wherein the volume fraction of hydrogen in the mixed gas is 5%, and calcining at 400° C. for 3 h, a portion of the indium trioxide is reduced to metallic indium, and a portion of the lattice oxygen in the indium trioxide is oxidized to form oxygen vacancies, thereby obtaining a metallic indium / mesoporous indium trioxide composite material, the mass of the product being 0.8 g;

[0108] (10) The metal indium / mesoporous indium trioxide composite material prepared in step (9) is mixed with deionized water in a mass ratio of 4:1, and ground into a paste slurry, and the slurry is applied to an Al2O3 substrate having two parallel, annular and separate gold electrodes on its outer surface. 2 O 3 The ceramic tube surface was baked under infrared light for 40 minutes to obtain a sensitive film based on surface functionalized zinc oxide on the ceramic tube surface. The thickness of the sensitive film was 180 μm. Then a nickel-chromium alloy heating coil with a resistance value of 40 Ω was passed through the Al 2 O 3 The ceramic tube is used as the heating wire, and finally welded and packaged as a side-heated gas sensor; Al 2 O 3 The length of the ceramic tube is 3 mm, the outer diameter is 1.3 mm, and the inner diameter is 0.9 mm; the width of the annular Au electrode is 0.7 mm, and the distance between the two electrodes is 1.7 mm;

[0109] (11) The acetone gas sensor based on the metal indium / mesoporous indium trioxide composite material obtained in step (10) is aged at 320° C. for 12 hours to complete the aging treatment of the gas sensor, thereby obtaining a resistive acetone sensor based on the metal indium / mesoporous indium trioxide composite material.

[0110] Example 6

[0111] (1) 3.0 g of triblock copolymer P123 (EO 20 PO 70 EO 20 , molecular weight 5800, Adrich Chemical Reagent Company) was added to 70mL of water; then 8.0g of hydrochloric acid and 1.0

[0112] g n-butanol, stirred at room temperature for 2 h, under the action of hydrochloric acid and n-butanol, P123 was dissolved and rod-shaped micelles were formed, and a mixed solution of P123 micelles, hydrochloric acid and n-butanol was obtained;

[0113] (2) adding 5.0 g of tetraethyl orthosilicate to the mixed solution containing P123 micelles, hydrochloric acid and n-butanol obtained in step (1), and stirring at 35° C. for 30 h; then charging the mixed solution into a reaction kettle, and subjecting it to hydrothermal treatment at 100° C. for 24 h; the tetraethyl orthosilicate is hydrolyzed to generate silica, and the generated silica is coated on the surface of the P123 micelles; the obtained reaction solution is centrifuged, washed with ethanol, and dried to obtain a mesoporous silica material containing P123;

[0114] (3) calcining the mesoporous silica material containing P123 obtained in step (2) at 500° C. for 2 h.

[0115] P123 decomposes into carbon dioxide and water under high temperature conditions to obtain mesoporous silica material;

[0116] (4) adding the mesoporous silica material obtained in step (3) to 10 mL of ethanol, then adding 0.5 g of indium nitrate to the mixed solution, and stirring at room temperature for 3 h; drying the resulting mixture at 40° C. for 36 h, dispersing the indium nitrate into the pores of the mesoporous silica, and obtaining an indium nitrate-filled mesoporous silica material;

[0117] (5) calcining the indium nitrate-filled mesoporous silica material obtained in step (4) at 280° C. for 2 h. During the calcination process, the indium nitrate is converted into indium trioxide to obtain an indium trioxide-filled mesoporous silica material;

[0118] (6) adding the indium trioxide-filled mesoporous silica material obtained in step (5) to 8 mL of ethanol, then adding 0.3 g of indium nitrate to the mixed solution, and stirring at room temperature for 3 h; drying the resulting mixture at 50° C. for 36 h, dispersing the indium nitrate into the pores of the indium trioxide-filled mesoporous silica material, and obtaining a mesoporous silica material co-filled with indium nitrate and indium trioxide;

[0119] (7) filling the mesoporous silica material with the indium nitrate and indium trioxide obtained in step (6), and calcining at 600° C. for 2 h. During the calcination process, the indium nitrate is converted into indium trioxide to obtain the indium trioxide-filled mesoporous silica material;

[0120] (8) Add the indium trioxide-filled mesoporous silica material obtained in step (7) to a solution having a concentration of 20

[0121] mL of 3M sodium hydroxide solution, stirred at 80°C for 2h; sodium hydroxide dissolved silicon dioxide into sodium silicate soluble in water, and the obtained solution was centrifuged, washed with ethanol, and dried to obtain a mesoporous indium trioxide material;

[0122] (9) The mesoporous indium trioxide material obtained in step (8) is placed in a hydrogen and nitrogen mixed gas protection, wherein the volume fraction of hydrogen in the mixed gas is 10%, and calcined at 400° C. for 4 h, wherein a portion of the indium trioxide is reduced to metallic indium, and a portion of the lattice oxygen in the indium trioxide is oxidized to form oxygen vacancies.

[0123] The metal indium / mesoporous indium trioxide composite material was obtained, and the product mass was 0.6g;

[0124] (10) The metal indium / mesoporous indium trioxide composite material prepared in step (9) is mixed with deionized water in a mass ratio of 3:1, and ground into a paste slurry, and the slurry is applied to an Al2O3 substrate having two parallel, annular and separate gold electrodes on its outer surface. 2 O 3 The ceramic tube surface was baked under infrared light for 40 minutes to obtain a sensitive film based on surface functionalized zinc oxide on the ceramic tube surface. The thickness of the sensitive film was 180 μm. Then a nickel-chromium alloy heating coil with a resistance value of 40 Ω was passed through the Al 2 O 3 The ceramic tube is used as the heating wire, and finally welded and packaged as a side-heated gas sensor; Al 2 O 3 The length of the ceramic tube is 3 mm, the outer diameter is 1.3 mm, and the inner diameter is 0.9 mm; the width of the annular Au electrode is 0.7 mm, and the distance between the two electrodes is 1.7 mm;

[0125] (11) The acetone gas sensor based on the metal indium / mesoporous indium trioxide composite material obtained in step (10) is aged at 320° C. for 8 hours to complete the aging treatment of the gas sensor, thereby obtaining a resistive acetone sensor based on the metal indium / mesoporous indium trioxide composite material.

[0126] like Figure 1 As shown, it can be seen that the composite material prepared by the present invention is formed by the aggregation of many nanoparticles, and there are abundant gaps between the nanoparticles.

[0127] like Figure 2 As shown, it can be seen that the composite material prepared by the present invention has a series of diffraction peaks, and these diffraction peaks belong to the characteristic diffraction peaks of metallic indium and indium trioxide, respectively, which proves that the composite material containing metallic indium and indium trioxide is successfully prepared.

[0128] like Figure 3 As shown, it can be seen that the composite material prepared by the present invention has two strong spectral peaks that can be fitted into two valence states of indium-based compounds, indicating that the indium element in the metal indium / mesoporous indium trioxide composite material exists as zero-valent metal indium and trivalent indium ions.

[0129] like Figure 4 As shown, it can be seen that the composite material prepared by the present invention has two strong spectral peaks that can be fitted into two valence states of indium-based compounds composed of lattice oxygen, oxygen vacancies and chemically adsorbed oxygen, among which the spectral peak area attributed to oxygen vacancies is larger, indicating that it has higher oxygen vacancies.

[0130] like Figure 5 As shown, it can be seen that the metal indium / mesoporous indium trioxide composite material-based sensor prepared by the present invention has good response recovery characteristics to 100 ppm acetone at 200° C., and the response recovery rate is relatively fast.

[0131] like Figure 6 As shown, it can be seen that the metal indium / mesoporous indium trioxide composite material-based acetone sensor prepared in the present invention has a very high and fast response to different concentrations of acetone at 200°C, and as the acetone concentration increases, the impact value of the device gradually increases.

[0132] like Figure 7 As shown, it can be seen that the metal indium / mesoporous indium trioxide composite material-based sensor prepared in the present invention has good response recovery characteristics to 100 ppm acetone at 250° C. and a fast response recovery rate.

[0133] like Figure 8 As shown, it can be seen that the metal indium / mesoporous indium trioxide composite material-based sensor prepared in the present invention has good response recovery characteristics to 100 ppm acetone at 300° C. and a fast response recovery rate.

[0134] like Fig. 9 As shown, it can be seen that the metal indium / mesoporous indium trioxide composite material-based sensor prepared by the present invention has good response recovery characteristics to 100 ppm acetone at 350° C. and a fast response recovery rate.

[0135] like Fig.10 As shown, it can be seen that the metal indium / mesoporous indium trioxide composite material-based sensor prepared by the present invention has good response recovery characteristics to 100 ppm acetone at 400° C., and the response recovery rate is relatively fast.

Claims

1. A resistive acetone sensor based on metal indium / mesoporous indium trioxide composite material, which is a tubular structure and consists of Al 2 O 3 Ceramic tube substrate, coated on Al 2 O 3 Two parallel and separate annular Au electrodes on the outer surface of the ceramic tube substrate, coated on Al 2 O 3 The gas sensitive film on the outer surface of the ceramic tube and the annular Au electrode passes through the Al 2 O 3 It consists of a nickel-chromium alloy heating coil inside the ceramic tube; Features: The material of the gas sensitive film is a metal indium / mesoporous indium trioxide composite material, and is prepared by the following steps: (1) adding 1.0-3.0 g of triblock copolymer P123 to 50-70 mL of water, and then sequentially adding 6.0-8.0 g of concentrated hydrochloric acid and 1.0-3.0 g of n-butanol thereto, and stirring at room temperature to obtain a mixed solution containing P123 micelles, hydrochloric acid and n-butanol; (2) adding 3.0-5.0 g of tetraethyl orthosilicate to the mixed solution containing P123 micelles, hydrochloric acid and n-butanol obtained in step (1), stirring at 35-45° C. and then placing in a reaction kettle for hydrothermal treatment; centrifuging the obtained reaction solution, washing with ethanol, and drying to obtain a mesoporous silica material containing P123; (3) calcining the mesoporous silica material containing P123 obtained in step (2) to obtain a mesoporous silica material; (4) adding the mesoporous silica material obtained in step (3) to 8-10 mL of ethanol, and then adding 0.5-0.8 g of indium nitrate to the mixed solution, stirring at room temperature and drying to obtain a mesoporous silica material filled with indium nitrate; (5) calcining the mesoporous silica material filled with indium nitrate obtained in step (4) to obtain a mesoporous silica material filled with indium trioxide; (6) adding the indium trioxide-filled mesoporous silica material obtained in step (5) to 8-10 mL of ethanol, and then adding 0.3-0.5 g of indium nitrate to the mixed solution, and drying at room temperature to obtain a mesoporous silica material filled with indium nitrate and indium trioxide; (7) calcining the mesoporous silica material filled with indium nitrate and indium trioxide obtained in step (6) to obtain a mesoporous silica material filled with indium trioxide; (8) adding the indium trioxide-filled mesoporous silica material obtained in step (7) to 20 to 40 mL of a 1 to 3 M sodium hydroxide solution, stirring at 60 to 80° C., centrifuging the resulting solution, washing with ethanol, and drying to obtain a mesoporous indium trioxide material; (9) The mesoporous indium trioxide material obtained in step (8) is placed in a mixed gas protection of hydrogen and nitrogen, wherein the volume fraction of hydrogen in the mixed gas is 5% to 10%, and a metallic indium / mesoporous indium trioxide composite material is obtained after calcination.

2. A resistive acetone sensor based on a metal indium / mesoporous indium trioxide composite material as claimed in claim 1, Features: Step (2) is a hydrothermal treatment at 100-120° C. for 24-36 hours, and steps (4) and (6) are drying at 40-50° C. for 24-36 hours.

3. A resistive acetone sensor based on a metal indium / mesoporous indium trioxide composite material as claimed in claim 1, Features: Step (3) is calcined at 500-600°C for 2-4h, step (5) is calcined at 260-280°C for 2-4h, step (7) is calcined at 500-600°C for 2-4h, and step (9) is calcined at 300-400°C for 2-4h.

4. A resistive acetone sensor based on a metal indium / mesoporous indium trioxide composite material as claimed in claim 1, Features: Al 2 O 3 The length of the ceramic tube is 3-5 mm, the outer diameter is 1.1-1.3 mm, and the inner diameter is 0.7-0.9 mm; the resistance of the nickel-chromium alloy heating coil is 30-40Ω; the width of the annular Au electrode is 0.7-0.9 mm, and the distance between the two electrodes is 1.7-1.9 mm; the thickness of the gas sensitive film is 180-220 μm.

5. A method for preparing a resistive acetone sensor based on a metal indium / mesoporous indium trioxide composite material according to any one of claims 1 to 4, comprising the following steps: (1) mixing the metal indium / mesoporous indium trioxide composite material with deionized water in a mass ratio of 3 to 5:1 and grinding the mixture into a paste slurry; coating the paste on an Al substrate having two parallel and separate annular Au electrodes on its outer surface; 2 O 3 Ceramic tube surface; (2) The device obtained in step (1) is baked under an infrared lamp for 20 to 40 minutes. After the sensitive material is dried, a nickel-chromium alloy heating coil with a resistance value of 30 to 40 Ω is passed through the Al 2 O 3 The ceramic tube is used as a heating wire and is welded and packaged as a side-heated gas sensor. (3) The device obtained in step (2) is aged at 280-320° C. for 8-12 h, thereby obtaining a resistive acetone sensor based on a metal indium / mesoporous indium trioxide composite material.

6. Use of a resistive acetone sensor based on a metal indium / mesoporous indium trioxide composite material as claimed in any one of claims 1 to 4 in detecting acetone.

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