Gold-modified fluorine-doped indium oxide composite material and preparation method and application thereof

Abstract

The invention relates to the technical field of gas sensitive materials, in particular to a gold-modified fluorine-doped indium oxide composite material as well as a preparation method and application thereof. In the gold-modified fluorine-doped indium oxide composite material provided by the invention, a base material is a two-dimensional nanorod-bundle-shaped fluorine-doped indium oxide self-assembled material, gold is dispersed on the surface of the base material in a nano-particle form, and by utilizing the strong Lewis acidity of gold nano-particles, activation of TEA molecules and reduction of reaction activation energy and the high electronegativity doping effect of base fluorine ions, the gold-modified fluorine-doped indium oxide composite material is prepared. The interference of water molecules on the gas-sensitive material in a high-humidity environment is effectively inhibited, TEA detection with stable humidity resistance, high sensitivity, quick response recovery and high selectivity at a low working temperature is successfully realized, and the method has excellent practical application value and industrial production prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of gas sensitive materials, and particularly relates to a gold modified fluorine-doped indium oxide composite material and a preparation method and application thereof. BACKGROUND

[0002] The information disclosed in the background of the present application is only intended to increase the understanding of the overall background of the present application and should not necessarily be regarded as acknowledging or implying in any form that the information constitutes prior art known to those skilled in the art.

[0003] At present, as one of the most widely used and most deeply researched gas sensitive elements, the detection mechanism of the resistance type semiconductor metal oxide gas sensor is mainly based on the oxidation-reduction reaction between the surface of the gas sensitive material and the target gas. The reaction is accompanied by an electron transfer process, which will cause the change of the metal oxide conduction band electron concentration and the bending of the energy band structure, and then cause the change of the material bulk phase conductivity, so as to realize the conversion and detection from chemical signal to electrical signal. Such sensors have played a key role in many fields such as organic synthesis, chemical production, automobile exhaust detection and food spoilage monitoring.

[0004] Triethylamine, as an important organic base and chemical intermediate, is widely used as a solvent, an extractant, an organic synthesis intermediate and a catalyst. In chemical production and storage environments, triethylamine may leak in the form of harmful gas, which has a strong irritating odor and poses a threat to human health. Long-term exposure may cause diseases such as emphysema. In addition, triethylamine is also one of the main volatile amine substances produced in the spoilage process of fish and other aquatic products, and is considered an important indicator for evaluating the freshness of aquatic products. Therefore, developing a gas sensor that can quickly and accurately detect triethylamine has important practical significance for real-time monitoring of food spoilage and ensuring food safety.

[0005] However, at present, the metal oxide-based gas sensor still generally faces the problems of weak humidity resistance, insufficient selectivity, high working temperature and slow response and recovery speed in actual detection of triethylamine, which greatly restricts its practical application in complex environments. SUMMARY

[0006] Therefore, the present application provides a gold modified fluorine-doped indium oxide composite material and a preparation method and application thereof. The composite material provided by the present application is a nanorod bundle fluorine-doped indium oxide structure loaded with gold nanoparticles with adjustable particle size on the surface, which can realize high sensitivity, high selectivity and fast response and recovery of TEA detection at low temperature, and has excellent practical application value and industrial production prospect.

[0007] In order to achieve the above purpose, the present application is realized by the following technical scheme: In a first aspect, the present application provides a method for preparing a gold-modified fluorine-doped indium oxide composite material, comprising the following steps: (1) adding an indium source, a surfactant, an alkali source and a fluorine source into deionized water, uniformly mixing and then performing a hydrothermal reaction to obtain an indium oxyfluoride precursor, and annealing the indium oxyfluoride precursor to obtain a fluorine-doped indium oxide matrix; (2) adding the fluorine-doped indium oxide matrix into deionized water, uniformly dispersing, then adding a gold source and uniformly mixing, and then sequentially adding a dispersant and a reducing agent, stirring and reacting, after the reaction is completed, centrifuging, washing and drying to obtain the gold-modified fluorine-doped indium oxide composite material.

[0008] In the hydrothermal reaction process, indium ions first react with hydroxide ions to form indium hydroxide nuclei. Subsequently, the indium hydroxide reacts with fluorine ions hydrolyzed from the fluorine source to form an indium oxyfluoride precursor. The surfactant effectively inhibits the spontaneous agglomeration of the nuclei and guides the preferential growth of the nuclei by reducing the surface energy thereof. This regulation mechanism promotes the self-assembly of two-dimensional indium hydroxide nanosheets, and due to the pinning effect of the fluorine ions, a unique indium oxyfluoride two-dimensional nanorod bundle precursor structure is formed. In the annealing process, the indium oxyfluoride pyrolyzes, and the fluorine ions are embedded into the crystal lattice to form a special fluorine-doped indium oxide nanorod bundle, effectively avoiding the loss of the fluorine source in the form of HF at high temperatures. By utilizing the doping effect of the fluorine ions, the aggregation of free electrons in the indium oxide material is realized, providing a large number of sites for the adsorption and reaction of TEA. Meanwhile, the fluorine ions can also act as a specific Lewis acid site, enhancing the adsorption of TEA and helping to improve the gas sensing performance.

[0009] Further, in step (1), the fluorine-doped indium oxide matrix is a nanorod self-assembled rod bundle. In the in-situ modification process of gold nanoparticles, the dispersant is used to ensure the uniform dispersion of gold ions in the fluorine-doped indium oxide nanorod bundle matrix. By regulating the aggregate state of gold ions and the reducing strength of the solution, the size of gold nanoparticles is continuously regulated.

[0010] Further, in step (1), the hydrothermal reaction refers to a reaction performed under a high atmospheric pressure generated by heating a reaction system in a closed system using deionized water as a solvent.

[0011] Further, in step (1), the indium source is selected from at least one of indium chloride (InCl3), indium nitrate (In(NO3)3), indium acetylacetonate (In(C5H7O2)3) or indium acetate (In(CH3COO)3).

[0012] Further, in step (1), the surfactant is cetyltrimethylammonium bromide (CTAB). 19 H42 Sodium dodecylbenzenesulfonate (C 18 H 29 NaO3S), polyvinylpyrrolidone (C6H9NO n ) or ascorbic acid (C6H8O6).

[0013] Further, in step (1), the alkali source is at least one of urea (CH4N2O), hexamethylenetetramine (C6H 12 N4), ammonia (NH3·H2O) or sodium hydroxide (NaOH).

[0014] Further, in step (1), the fluorine source is at least one of sodium fluoride (NaF), potassium fluoride (KF), ammonium fluoride (NH4F) or fluorosilicic acid (H2SiF6).

[0015] Further, in step (1), the molar ratio of the indium source, the surfactant, the alkali source and the fluorine source is 1:2-5:2-8:1-2.

[0016] Further, in step (1), the temperature of the hydrothermal reaction is 80-160 ℃ and the time is 8-16 h.

[0017] Further, in step (1), the temperature of the annealing treatment is 400-600 ℃ and the time is 1-3 h.

[0018] Further, in step (2), the gold source is at least one of gold acetate (C6H9AuO6), sodium chloroaurate (NaAuCl4), ammonium chloroaurate (NH4AuCl4) or chloroauric acid (HAuCl4).

[0019] Further, in step (2), the dispersant is at least one of L-lysine (C6H 14 N2O2), cetyltrimethylammonium bromide (C 19 H 42 BrN) or tannic acid (C 76 H 52 O 46 ).

[0020] Further, in step (2), the reducing agent is at least one of citric acid (C6H8O7), sodium citrate (C6H5O7Na3) or sodium borohydride (NaBH4).

[0021] Further, in step (2), the molar ratio of the fluorine-doped indium oxide matrix, the gold source, the dispersant and the reducing agent is 1:0.01-0.05:5-20:5-20.

[0022] Further, in step (2), the time of the stirring reaction is 1-3 h.

[0023] In a second aspect, the application provides the gold-modified fluorine-doped indium oxide composite prepared by the preparation method of the first aspect.

[0024] Further, in the gold-modified fluorine-doped indium oxide composite, the base material is a nanorod self-assembled rod bundle fluorine-doped indium oxide self-assembled material, and the gold is dispersed on the surface of the base material in the form of nanoparticles.

[0025] Further, the diameter of the nanorod self-assembled rod bundle fluorine-doped indium oxide is 20-30 nm.

[0026] Further, the particle size of the gold nanoparticles is 6.8-16.5 nm; by changing the types and ratios of the dispersing agent and the reducing agent, the surface dispersion state of the gold ions and the aggregation effect of the gold nanoparticles during the in-situ gold nanoparticle loading process can be changed, and the particle size of the gold nanoparticles can be adjusted in the range of 6.8-16.5 nm.

[0027] The fluorine-doped indium oxide is an n-type semiconductor with high conductivity and a narrow band gap, which provides the main gas-sensitive reaction sites as the base of the composite material. The fluorine ions are doped in the indium oxide lattice in the form of lattice substitution, effectively improving the electronegativity and carrier concentration of the material, providing more gas-sensitive reaction sites and diffusion paths, which helps to accelerate the TEA sensing rate and improve the sensitivity, and simultaneously inhibits the toxic effect of water molecules on metal oxides. Gold is a noble metal nanoparticle with high catalytic activity and high Lewis acidity, which is uniformly dispersed on the surface of the fluorine-doped indium oxide material. The metal-semiconductor Schottky heterojunction can induce the migration of free electrons in the indium oxide to the surface interface, accelerate the electron transfer efficiency, and form more chemisorbed oxygen to participate in and accelerate the reaction with TEA by using the high chemical sensitization and electronic sensitization properties of gold nanoparticles. By changing the particle size distribution of the gold nanoparticles, the strength of the local plasmonic oscillation effect can be controlled, the number of Schottky heterojunctions can be changed, which is beneficial to the improvement of the heterojunction electron transfer efficiency and the regulation of the reactive chemisorbed oxygen sites, and the rapid response and recovery of TEA can be achieved by changing the interface temperature. The selectivity, sensitivity and working temperature of the gas-sensitive material are simultaneously optimized.

[0028] In a third aspect, the application provides a gas-sensitive element, which comprises a substrate, and a sensing layer arranged on the surface of the substrate, wherein the gas-sensitive material of the sensing layer is the gold-modified fluorine-doped indium oxide composite of the second aspect.

[0029] In a fourth aspect, the application provides a preparation method of the gas-sensitive element of the third aspect, which comprises the following steps: mixing the gold-modified fluorine-doped indium oxide composite of the second aspect with a solvent to form a slurry, coating the slurry on the surface of the substrate, and drying, thereby obtaining the gas-sensitive element.

[0030] Further, the substrate is a ceramic substrate.

[0031] Further, the solvent is at least one of deionized water (H2O) and anhydrous ethanol (C2H6O), preferably deionized water.

[0032] Further, the mass ratio of the gold-modified fluorine-doped indium oxide composite material to the solvent is 1:2-6, preferably 1:5.

[0033] Further, before the slurry is coated on the surface of the substrate, the substrate is subjected to a drying treatment. Specifically, the drying temperature is 70-100 ℃, and the drying time is 2-6 min.

[0034] Further, after the slurry is coated on the surface of the substrate, the drying temperature is 80-120 ℃, and the drying time is 8-24 h. Under this condition, the slurry on the surface of the substrate can be completely dried.

[0035] In a fifth aspect, the present application provides a use of the gold-modified fluorine-doped indium oxide composite material of the second aspect or the gas sensor of the fourth aspect in detecting TEA.

[0036] Further, the lower limit of the detection of TEA is 1 ppm.

[0037] Further, the detection temperature is 100-240 ℃.

[0038] Compared with the prior art, the present application has the following beneficial effects: (1) The present application realizes a gold-modified fluorine-doped indium oxide composite material system with adjustable particle size distribution by using hydrothermal synthesis, annealing and in-situ chemical reduction process. In the hydrothermal synthesis process, the hydrothermal precursor reaction and annealing process are effectively utilized to realize efficient preparation of fluorine-doped indium oxide material. The loss of fluorine dopant in the form of HF during high-temperature annealing of the precursor material is effectively avoided, which leads to low doping efficiency. The high electronegativity of the fluorine dopant induces the formation of more free electrons on the surface, promotes the exchange of electrons between the material and TEA, and enhances the gas sensing reaction process. The high electronegativity of the fluorine dopant inhibits the interference of water molecules under high humidity, optimizes the humidity resistance stability of the sensing material, and realizes high sensitivity and humidity resistance for TEA detection.

[0039] (2) In the in-situ chemical reduction process of the preparation method, the electrostatic adsorption of gold ions on the surface of the fluorine-doped indium oxide substrate and the anti-agglomeration effect of the dispersant are utilized to realize the uniform dispersion of gold ions on the surface of the material. By adjusting the type and concentration of the reducing agent and the dispersant, the particle size of the gold nanoparticles can be continuously controlled. This avoids the agglomeration and growth of the supported noble metal nanoparticles in the traditional oxide support system, and the preparation process is simple and the nanodispersion effect is excellent.

[0040] (3) The gold modified fluorine doped indium oxide composite material prepared by the method has adjustable particle size distribution, the substrate fluorine doped indium oxide is formed by self-assembly of nanorod bundles with nanometer particles stacked, the unique micro-morphology significantly increases the specific surface area of the material, a large number of gaps between the nanometer particles provide a large number of diffusion channels for the gas to be detected, and the gas sensitivity and response recovery speed of the material can be effectively improved.

[0041] (4) The gold modified fluorine doped indium oxide composite material prepared by the method has excellent gas sensitive performance in the detection of TEA, the response value of 100 ppm TEA can reach 160.7 at 30% RH and 200 DEG C, the TEA gas sensitive performance is optimized by controlling the particle size of gold nanoparticles, the working temperature of the sensor can be further reduced to 100 DEG C by optimizing the particle size, and excellent selectivity can still be exhibited in the detection of TEA. BRIEF DESCRIPTION OF DRAWINGS

[0042] The drawings accompanying the specification of the present application form a part thereof, serve to provide further understanding of the present application, and together with the specification explain the exemplary embodiments of the present application, and do not constitute an improper limitation on the present application.

[0043] Figure 1 The XRD diagram of the gold modified fluorine doped indium oxide composite material prepared for examples 5-7 of the present application and the calculation results of the average particle size of the material; wherein (a) is the XRD diagram of the gold modified fluorine doped indium oxide composite material prepared for examples 5-7 of the present application; (b) is the XRD enlarged diagram of the gold modified fluorine doped indium oxide composite material prepared for examples 5-7 of the present application; (c) is the calculation results of the average particle size of the gold modified fluorine doped indium oxide composite material prepared for examples 5-7 of the present application; Figure 2 The SEM diagrams of the fluorine doped indium oxide material, the gold modified fluorine doped indium oxide composite material and the fluorine doped indium oxide material prepared for examples 1-4 and comparative examples 1-2 of the present application; wherein (a) is example 1, the scale is 500 nm; (b) is example 2, the scale is 300 nm; (c) is example 3, the scale is 300 nm; (d) is example 4, the scale is 300 nm; (e) is comparative example 1, the scale is 5 microns; (f) is comparative example 2, the scale is 300 nm; Figure 3 The TEM, HRTEM, HAADF-STEM and EDS diagrams of the gold modified fluorine doped indium oxide composite material prepared for example 3 of the present application; wherein (a) is a TEM diagram, the scale is 200 nm; (b) is a TEM diagram, the scale is 100 nm; (c) is a selected area electron diffraction pattern obtained from the edge position of the enlarged diagram (b), the scale is 5 nm -1(d) is a HRTEM image, scale bar 20 nm; (d1) is the lattice diffraction fringes of indium fluoride doped indium oxide; (d2) is the lattice diffraction fringes of gold nanoparticles; (e) is a HAADF-STEM image, scale bar 200 nm; (f) is an EDS map of In element; (g) is an EDS map of O element; (h) is an EDS map of F element; (i) is an EDS map of Au element; Figure 4 TEM images and particle size statistical distribution diagrams of gold modified indium fluoride doped indium oxide composite materials prepared in Examples 5-7 and Comparative Example 3 of the present application; wherein (a) is Example 5, scale bar 200 nm; (b) is Example 6, scale bar 200 nm; (c) is Example 7, scale bar 200 nm; (d) is Comparative Example 3, scale bar 200 nm; (e) is the gold nanoparticle particle size statistical distribution diagram of Example 5; (f) is the gold nanoparticle particle size statistical distribution diagram of Example 6; (g) is the gold nanoparticle particle size statistical distribution diagram of Example 7; (h) is the gold nanoparticle particle size statistical distribution diagram of Comparative Example 3; Figure 5 FTIR images of gold modified indium fluoride doped indium oxide composite materials prepared in Examples 5-7 of the present application; wherein (a) is an FTIR image with a scanning wave number range of 4000-500 cm-1; (b) is an FTIR image with a scanning wave number range of 700-400 cm-1; -1 -1 Figure 6 NH3-TPD and O2-TPD spectra of gold modified indium fluoride doped indium oxide composite materials prepared in Examples 5-7 of the present application; wherein (a) is an NH3-TPD spectrum; (b) is an O2-TPD spectrum; Figure 7 UV diffuse reflectance spectra and band gap-absorbance spectra of indium fluoride doped indium oxide materials and gold modified indium fluoride doped indium oxide composite materials prepared in Examples 1-4 of the present application; wherein (a) is a UV diffuse reflectance spectrum; (b) is a band gap-absorbance spectrum; Figure 8 UV diffuse reflectance spectra, band gap-absorbance and gold particle size-UV reflectance spectra of gold modified indium fluoride doped indium oxide composite materials prepared in Examples 3, 5-7 of the present application; wherein (a) is a UV diffuse reflectance spectrum; (b) is a band gap-absorbance spectrum; (c) is a gold particle size-UV reflectance spectrum; Figure 9 ​​The simulated interface electric field intensity distribution diagram of the gold-modified fluorine-doped indium oxide composite material prepared in Example 3, 5-7 of the present application; wherein (a1) is the simulated interface electric field intensity distribution diagram of the gold-modified fluorine-doped indium oxide composite material prepared in Example 3; (a2) is an enlarged view of (a1); (b1) is the simulated interface electric field intensity distribution diagram of the gold-modified fluorine-doped indium oxide composite material prepared in Example 5; (b2) is an enlarged view of (b1); (c1) is the simulated interface electric field intensity distribution diagram of the gold-modified fluorine-doped indium oxide composite material prepared in Example 6; (c2) is an enlarged view of (c1); (d1) is the simulated interface electric field intensity distribution diagram of the gold-modified fluorine-doped indium oxide composite material prepared in Example 7; (d2) is an enlarged view of (d1); Figure 10 The simulated interface thermal field intensity distribution diagram of the fluorine-doped indium oxide material and the gold-modified fluorine-doped indium oxide composite material prepared in Example 1, 3, 5-7 of the present application; wherein (a1) is the simulated interface thermal field intensity distribution diagram of the fluorine-doped indium oxide material prepared in Example 1; (a2) is an enlarged view of (a1); (b1) is the simulated interface thermal field intensity distribution diagram of the gold-modified fluorine-doped indium oxide composite material prepared in Example 3; (b2) is an enlarged view of (b1); (c1) is the simulated interface thermal field intensity distribution diagram of the gold-modified fluorine-doped indium oxide composite material prepared in Example 5; (c2) is an enlarged view of (c1); (d1) is the simulated interface thermal field intensity distribution diagram of the gold-modified fluorine-doped indium oxide composite material prepared in Example 6; (d2) is an enlarged view of (d1); (e1) is the simulated interface thermal field intensity distribution diagram of the gold-modified fluorine-doped indium oxide composite material prepared in Example 7; (e2) is an enlarged view of (e1); Figure 11 The resistance-working temperature diagram under different relative humidities and the resistance proportion diagram under different temperatures of 80% and 30% RH of the gold-modified fluorine-doped indium oxide composite material prepared in Example 3, 5-7 of the present application; wherein (a) is the resistance-working temperature diagram under different relative humidities; (b) is the resistance proportion diagram; Figure 12 The TEA response value-working temperature diagram under different relative humidities and the TEA response value proportion diagram under different temperatures of 80% and 30% RH of the gold-modified fluorine-doped indium oxide composite material prepared in Example 3, 5-7 of the present application; wherein (a) is the TEA response value-working temperature diagram under different relative humidities; (b) is the TEA response value proportion diagram; Figure 13The response recovery curve of the gold modified fluorine doped indium oxide composite material prepared in Example 5-7 of the present application at 200 ℃ for 100 ppm TEA and the response recovery time of the gold modified fluorine doped indium oxide composite material prepared in Examples 3, 5-7 of the present application at 200 ℃ for 100 ppm TEA; wherein (a) is the response recovery curve; (b) is the response recovery time curve; Figure 14 The schematic diagram of the gas sensor prepared in Example 10 of the present application; Figure 15 The response value of the fluorine doped indium oxide material, the gold modified fluorine doped indium oxide composite material and the fluorine-free doped indium oxide material prepared in Examples 1, 6 and Comparative Examples 1, 3 of the present application at 100 ℃ for 100 ppm TEA; Figure 16 The response recovery curve of the gold modified fluorine doped indium oxide composite material prepared in Example 3 of the present application at 100 ℃ for 1-100 ppm TEA. DETAILED DESCRIPTION

[0044] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0045] The technical solutions of the present application will be further described below in combination with specific examples.

[0046] Example 1 InCl3(0.3 mmol), C6H8O6(0.9 mmol), NaOH (1.8 mmol) and H2SiF6(0.3 mmol) were dissolved into 48 mL of deionized water and mixed uniformly, and then hydrothermal reaction was carried out at 80 ℃ for 16 h. After centrifugal washing and drying, the fluorine doped indium oxide material was obtained by annealing at 600 ℃ for 1 h. 19 H 42 BrN (0.6 mmol), NH3·H2O (0.6 mmol) and NaF (0.6 mmol) were dissolved into 12 mL of deionized water and mixed uniformly, and then hydrothermal reaction was carried out at 100 ℃ for 8 h. After centrifugal washing and drying, the fluorine doped indium oxide material was obtained by annealing at 400 ℃ for 2 h.

[0047] Example 2 InCl3(0.3 mmol), C6H8O6(0.9 mmol), NaOH (1.8 mmol) and H2SiF6(0.3 mmol) were dissolved into 48 mL of deionized water and mixed uniformly, and then hydrothermal reaction was carried out at 80 ℃ for 16 h. After centrifugal washing and drying, the fluorine doped indium oxide material was obtained by annealing at 600 ℃ for 1 h.

[0048] The prepared fluorine doped indium oxide (0.05 mmol), C6H9AuO6(0.0005 mmol), C6H14 N2O2 (1 mmol) and NaBH4 (0.25 mmol) were added to 12 mL of deionized water, and after stirring for 3 h, a gold-modified fluorine-doped indium oxide composite material was obtained.

[0049] Example 3 In(C5H7O2)3 (0.3 mmol), C 18 H 29 NaO3S (1.5 mmol), NaOH (2.4 mmol), and NaF (0.6 mmol) were dissolved in 48 mL of deionized water, mixed uniformly, and then subjected to hydrothermal reaction at 160 °C for 8 h. After the reaction product was centrifuged, washed, and dried, a fluorine-doped indium oxide material was obtained by annealing at 400 °C for 3 h.

[0050] The prepared fluorine-doped indium oxide (0.05 mmol), HAuCl4 (0.001 mmol), C6H 14 N2O2 (1 mmol) and C6H5O7Na3 (0.25 mmol) were added to 30 mL of deionized water, and after stirring for 1 h, a gold-modified fluorine-doped indium oxide composite material was obtained.

[0051] Example 4 InCl3 (0.3 mmol), C 19 H 42 BrN (0.6 mmol), CH4N2O (1.2 mmol), and KF (0.6 mmol) were dissolved in 30 mL of deionized water, mixed uniformly, and then subjected to hydrothermal reaction at 140 °C for 10 h. After the reaction product was centrifuged, washed, and dried, a fluorine-doped indium oxide material was obtained by annealing at 500 °C for 2 h.

[0052] The prepared fluorine-doped indium oxide (0.05 mmol), C6H9AuO6 (0.0025 mmol), C6H 14 N2O2 (0.5 mmol) and C6H5O7Na3 (0.6 mmol) were added to 24 mL of deionized water, and after stirring for 1.5 h, a gold-modified fluorine-doped indium oxide composite material was obtained.

[0053] Example 5 In(NO3)3 (0.3 mmol), C 18 H 29 NaO3S (0.9 mmol), C6H 12N4(1.5 mmol) and NaF (0.6 mmol) were dissolved in 30 mL of deionized water, mixed uniformly, and then hydrothermally reacted at 140 °C for 10 h. After the reaction product was centrifuged, washed, and dried, a fluorine-doped indium oxide material was obtained by annealing at 500 °C for 2 h.

[0054] The prepared fluorine-doped indium oxide (0.05 mmol), NaAuCl4(0.001 mmol), C 19 H 42 BrN (0.75 mmol) and NaBH4(0.75 mmol) were added to 36 mL of deionized water, stirred for 2 h to obtain a gold-modified fluorine-doped indium oxide composite material.

[0055] Example 6 In(C5H7O2)3(0.3 mmol), C6H8O6(0.6 mmol), CH4N2O (1.8 mmol), and KF (0.45 mmol) were dissolved in 20 mL of deionized water, mixed uniformly, and then hydrothermally reacted at 120 °C for 10 h. After the reaction product was centrifuged, washed, and dried, a fluorine-doped indium oxide material was obtained by annealing at 450 °C for 1 h.

[0056] The prepared fluorine-doped indium oxide (0.05 mmol), C6H9AuO6(0.001 mmol), C6H 14 N2O2 (0.25 mmol) and C6H8O7(0.75 mmol) were added to 25 mL of deionized water, stirred for 1.5 h to obtain a gold-modified fluorine-doped indium oxide composite material.

[0057] Example 7 InCl3(0.3 mmol), C6H8O6(0.9 mmol), C6H 12 N4(1.5 mmol) and NH4F (0.6 mmol) were dissolved in 24 mL of deionized water, mixed uniformly, and then hydrothermally reacted at 140 °C for 12 h. After the reaction product was centrifuged, washed, and dried, a fluorine-doped indium oxide material was obtained by annealing at 500 °C for 1 h.

[0058] The prepared fluorine-doped indium oxide (0.05 mmol), NH4AuCl4(0.001 mmol), C 19 H 42 BrN (0.5 mmol) and C6H5O7Na3(0.25 mmol) were added to 48 mL of deionized water, stirred for 2 h to obtain a gold-modified fluorine-doped indium oxide composite material.

[0059] Example 8 Combine In(CH3COO)3 (0.3 mmol), (C6H9NO) n 0.9 mmol of NaOH (1.5 mmol) and 0.6 mmol of KF were dissolved in 48 mL of deionized water and mixed evenly. The mixture was then subjected to hydrothermal reaction at 100 °C for 8 h. After centrifugation, washing and drying of the reaction product, it was annealed at 500 °C for 1 h to obtain fluorine-doped indium oxide material.

[0060] The prepared fluorine-doped indium oxide (0.05 mmol), NaAuCl4 (0.0025 mmol), and C 76 H 52 O 46 Gold-modified fluorine-doped indium oxide composite material was obtained by adding 1 mmol of NaBH4 and 1 mmol of NaBH4 to 24 mL of deionized water and stirring for 2 h.

[0061] Example 9 Add In(C5H7O2)3 (0.3 mmol), C 18 H 29 NaO3S (0.6 mmol), C6H 12 N4 (2.1 mmol) and NaF (0.3 mmol) were dissolved in 12 mL of deionized water and mixed evenly. The mixture was then subjected to hydrothermal reaction at 120 °C for 16 h. After centrifugation, washing and drying of the reaction product, it was annealed at 600 °C for 1 h to obtain fluorine-doped indium oxide material.

[0062] The prepared fluorine-doped indium oxide (0.05 mmol), C6H9AuO6 (0.001 mmol), and C6H 14 N2O2 (0.75 mmol) and C6H5O7Na3 (0.75 mmol) were added to 48 mL of deionized water and stirred for 1 h to obtain a gold-modified fluorine-doped indium oxide composite material.

[0063] Comparative Example 1 Add InCl3 (0.3 mmol) and C 19 H 42 BrN (0.9 mmol) and NH3·H2O (1.2 mmol) were dissolved in 24 mL of deionized water and mixed evenly. The mixture was then subjected to hydrothermal reaction at 120 °C for 4 h. After centrifugation, washing and drying of the reaction product, it was annealed at 500 °C for 2 h to obtain fluorine-free indium oxide material.

[0064] Comparative Example 2 Combine In(CH3COO)3 (0.3 mmol), (C6H9NO) nThe InF3-doped indium oxide material was prepared by dissolving In(C5H7O2)3(0.3 mmol), NaOH (1.5 mmol), and KF (0.9 mmol) into 48 mL of deionized water, mixing uniformly, and then hydrothermally reacting at 100°C for 8 h. The reaction product was centrifuged, washed, and dried, and then the InF3-doped indium oxide material was obtained by annealing at 500°C for 1 h.

[0065] Comparative Example 3 The InF3-doped indium oxide material was prepared by dissolving In(C5H7O2)3(0.3 mmol), NaOH (1.5 mmol), and KF (0.9 mmol) into 48 mL of deionized water, mixing uniformly, and then hydrothermally reacting at 100°C for 8 h. The reaction product was centrifuged, washed, and dried, and then the InF3-doped indium oxide material was obtained by annealing at 500°C for 1 h. 18 H 29 The InF3-doped indium oxide material was prepared by dissolving In(C5H7O2)3(0.3 mmol), NaOH (1.5 mmol), and KF (0.9 mmol) into 48 mL of deionized water, mixing uniformly, and then hydrothermally reacting at 100°C for 8 h. The reaction product was centrifuged, washed, and dried, and then the InF3-doped indium oxide material was obtained by annealing at 500°C for 1 h. 12 N4(1.5 mmol) and NaF (0.6 mmol) into 48 mL of deionized water, mixing uniformly, and then hydrothermally reacting at 100°C for 8 h. The reaction product was centrifuged, washed, and dried, and then the InF3-doped indium oxide material was obtained by annealing at 500°C for 1 h.

[0066] The gold-modified InF3-doped indium oxide composite material was prepared by adding the prepared InF3-doped indium oxide (0.05 mmol), NH4AuCl4(0.001 mmol), C6H 14 N2O2(0.15 mmol), and NaBH4(0.15 mmol) into 24 mL of deionized water, stirring for 2 h, and then obtaining the gold-modified InF3-doped indium oxide composite material.

[0067] Comparative Example 4 The InF3-doped indium oxide material was prepared by dissolving InCl3(0.3 mmol), C 18 H 29 The InF3-doped indium oxide material was prepared by dissolving InCl3(0.3 mmol), C 12 N4(1.2 mmol) into 30 mL of deionized water, mixing uniformly, and then hydrothermally reacting at 140°C for 10 h. The reaction product was centrifuged, washed, and dried, and then the InF3-doped indium oxide material was obtained by annealing at 500°C for 2 h.

[0068] Example 10 The gas sensing element and the preparation method thereof include a ceramic substrate, a platinum wire lead, a gas sensing material layer, and a gold electrode. The preparation method specifically includes the following steps: The gas sensing element was prepared by mixing the InF3-doped indium oxide prepared in Example 1 and the gold-modified InF3-doped indium oxide composite material prepared in Examples 2-9 with deionized water at a mass ratio of 1:5, grinding uniformly to form a slurry, uniformly coating the slurry on the ceramic substrate, placing the ceramic substrate in a 80°C oven to dry for 5 min, repeating the coating and drying process five times, placing the ceramic substrate coated with the gas sensing material in a 100°C oven to dry for 12 h, and connecting the platinum wire lead.

[0069] Performance test: Figure 1 XRD patterns of gold-modified fluorine-doped indium oxide composite materials prepared in Examples 5-7 and calculation results of average particle size of the materials; wherein (a) is an XRD pattern of the gold-modified fluorine-doped indium oxide composite material prepared in Examples 5-7; (b) is an XRD enlarged pattern of the gold-modified fluorine-doped indium oxide composite material prepared in Examples 5-7; and (c) is a calculation result of the average particle size of the gold-modified fluorine-doped indium oxide composite material prepared in Examples 5-7. As can be seen from Figure (a), the gold-modified fluorine-doped indium oxide composite materials prepared are all pure cubic phase structures, and no second-phase gold-related diffraction peaks exist, which is due to the low loading amount of gold nanoparticles on one hand, and the high dispersion of gold nanoparticles on the surface of the fluorine-doped indium oxide matrix on the other hand, which also indicates that the surface loading of gold nanoparticles will not damage or affect the crystal structure of fluorine-doped indium oxide itself. Figure (b) is an XRD pattern further enlarged at a diffraction angle of 29-32°, wherein the diffraction peaks contained correspond to the (222) crystal plane of indium oxide. After modification by gold nanoparticles, the diffraction peak does not shift significantly, revealing that the gold nanoparticles do not enter the crystal lattice of indium oxide but exist in the form of surface loading. The average particle size of the sample was calculated using the Debye-Scherrer method, and it can be seen that the particle size of the samples of Examples 5-7 is significantly smaller than the Debye length (25 nm) of indium oxide, indicating that the materials all exhibit a highly complete depletion state, which can provide more reactive free electrons and reaction sites, and is conducive to the improvement of gas sensing performance.

[0070] Figure 2SEM images of the fluorine-doped indium oxide material, the fluorine-doped indium oxide material and the gold-modified fluorine-doped indium oxide composite prepared in Examples 1-4 and Comparative Examples 1-2 of the present application; wherein (a) is Example 1, scale 500 nm; (b) is Example 2, scale 300 nm; (c) is Example 3, scale 300 nm; (d) is Example 4, scale 300 nm; (e) is Comparative Example 1, scale 5 μm; (f) is Comparative Example 2, scale 300 nm. As can be seen from (a), the fluorine-doped indium oxide material exhibits a clear nanorod bundle micro-nano structure, the diameter of the nanorod bundle is about 25 nm, and the surface morphology is uniform without other components loaded; as can be seen from (b)-(d), after modification by gold nanoparticles, the nanorod bundle structure of the fluorine-doped indium oxide material is not significantly damaged, and a small number of second phase components corresponding to the modified gold nanoparticles are observed on the surface, and no obvious agglomeration structure is observed, indicating that the gold nanoparticles are uniformly distributed and have low particle size and content; as can be seen from (e)-(f), the fluorine-doped indium oxide material exhibits a two-dimensional nanosheet-like self-assembled indium oxide material without obvious surface morphology damage, while after excessive fluorine doping, a large number of indium oxide nanorods are formed and serious agglomeration occurs, forming a nanosheet structure formed by agglomeration of a large number of nanorod bundles.

[0071] Figure 3 TEM, HRTEM, HAADF-STEM and EDS images of the gold-modified fluorine-doped indium oxide composite prepared in Example 3 of the present application; wherein (a) is a TEM image, scale 200 nm; (b) is a TEM image, scale 100 nm; (c) is a selected area electron diffraction pattern obtained from the edge position of the enlarged image (b), scale 5 nm -1(d) is HRTEM image, scale bar 20 nm; (d1) is the lattice diffraction fringes of indium fluoride-doped indium oxide; (d2) is the lattice diffraction fringes of gold nanoparticles; (e) is HAADF-STEM image, scale bar 200 nm; (f) is the EDS image of In element; (g) is the EDS image of O element; (h) is the EDS image of F element; (i) is the EDS image of Au element. As can be seen from (a)-(b), the material exhibits a typical nanorod self-assembly rod bundle structure, and the morphology is consistent with the SEM results, wherein the solid circle marked is the gold nanoparticles modified on the surface of the fluorine-doped indium oxide nanorod, (c) is the SAED image, wherein in addition to the diffraction ring of the indium oxide related crystal face, the (111) crystal face of Au is additionally observed, proving the existence of gold nanoparticles on the surface of the fluorine-doped indium oxide; (d) is the HRTEM image obtained by further enlarging the edge of the nanorod bundle, wherein (d1) and (d2) correspond to the (222) crystal face of In2O3 and the (111) crystal face of Au respectively, wherein the particle size of the Au nanoparticles is about 16.5 nm; (e) is the HAADF-STEM image, from which it can be seen that the gold nanoparticles are uniformly modified on the surface of the indium oxide nanorod bundle, and the element surface distribution images of (f)-(i) prove the uniform distribution of In, O, F and Au elements, and the aggregation area of Au element represents the modification of Au nanoparticles, which is consistent with the results of HRTEM and HAADF-STEM.

[0072] Figure 4 TEM images and particle size statistical distribution diagrams of the gold-modified fluorine-doped indium oxide composite material prepared in Comparative Example 3 for Examples 5-7; wherein (a) is Example 5, scale bar 200 nm; (b) is Example 6, scale bar 200 nm; (c) is Example 7, scale bar 200 nm; (d) is Comparative Example 3, scale bar 200 nm; (e) is the gold nanoparticle particle size statistical distribution diagram of Example 5; (f) is the gold nanoparticle particle size statistical distribution diagram of Example 6; (g) is the gold nanoparticle particle size statistical distribution diagram of Example 7; (h) is the gold nanoparticle particle size statistical distribution diagram of Comparative Example 3. As can be seen from (a)-(c), a large number of gold nanoparticles are uniformly distributed on the surface of the indium oxide nanorod bundle, and (e)-(g) respectively count the particle size of the gold nanoparticles on the surface of the indium oxide and the relationship between the particle sizes, and the average particle size of the gold nanoparticles is 14.0, 11.3 and 6.8 nm respectively, proving that by adjusting the dispersion state of the gold source in the solvent and the reduction system, the particle size of the gold nanoparticles can be continuously controlled. As can be seen from (d) and (h), when the amount of the reducing agent and the dispersing agent in the solvent is insufficient, the gold nanoparticles will obviously agglomerate and grow into larger nanoparticles, and after counting, the average particle size of the gold nanoparticles of Comparative Example 3 is 38.8 nm.

[0073] Figure 5FTIR spectra of gold modified fluorine-doped indium oxide composite materials prepared in Examples 5-7 of the present application; wherein (a) is an FTIR spectrum scanned in the range of 4000-500 cm -1 (b) is an FTIR spectrum scanned in the range of 700-400 cm -1 From Fig. (a), the infrared absorption peaks in the range of 3000-3400, 2362, 2333 and 400-700 cm -1 From Fig. (b), the peaks at 599.8, 561.9, 535.7 and 403.1 cm -1 indicate that the change of gold nanoparticle size does not affect the chemical bond state of indium oxide, proving that the gold nanoparticles do not exist in the indium oxide lattice but exist on the surface of the indium oxide in a supported form.

[0074] Figure 6 NH3-TPD and O2-TPD spectra of gold modified fluorine-doped indium oxide composite materials prepared in Examples 5-7 of the present application; wherein (a) is an NH3-TPD spectrum; (b) is an O2-TPD spectrum. From Fig. (a), it can be seen that the gold modified fluorine-doped indium oxide sample has abundant Lewis acid sites, mainly strong acid sites, which indicates that gold nanoparticle modification can improve the acidity of the material and provide more Lewis acid sites, which is helpful for TEA adsorption; from Fig. (b), it can be seen that all samples exhibit high oxygen active adsorption sites, confirming that gold nanoparticle modification can significantly improve the chemical adsorption oxygen concentration and oxygen activity on the surface of the material.

[0075] Figure 7 UV diffuse reflectance spectra and band gap-absorbance spectra of fluorine-doped indium oxide materials and gold modified fluorine-doped indium oxide composite materials prepared in Examples 1-4 of the present application; wherein (a) is a UV diffuse reflectance spectrum; (b) is a band gap-absorbance spectrum. From Figs. (a)-(b), it can be seen that after gold nanoparticle modification, the absorption rate of the material to ultraviolet light is significantly enhanced, and the band gap is reduced, indicating that gold nanoparticles can significantly enhance the light absorption performance of the material and increase the photo-generated carrier concentration of the material, promoting the gas sensitive reaction.

[0076] Figure 8UV diffuse reflectance spectra, band gap-absorbance and gold particle size-UV reflectance graphs of the gold modified fluorine-doped indium oxide composite materials prepared in Examples 3, 5-7; wherein (a) is the UV diffuse reflectance spectra; (b) is the band gap-absorbance graph; (c) is the gold particle size-UV reflectance graph. As can be seen from graphs (a)-(b), after modification by gold nanoparticles of different nanoparticle sizes, the overall absorbance and band gap of the material differ, and the statistical results in graph (c) show that the overall trend is that the gold nanoparticle size decreases, the absorbance of the material first decreases, then increases, and then continues to decrease, indicating that the size and surface state of the nanoparticles affect the absorbance of the material, which in turn changes the carrier concentration of the material.

[0077] Figure 9 Simulation interface electric field intensity distribution graphs of the gold modified fluorine-doped indium oxide composite materials prepared in Examples 3, 5-7; wherein (a1) is the simulation interface electric field intensity distribution graph of the gold modified fluorine-doped indium oxide composite material prepared in Example 3; (a2) is an enlarged view of (a1); (b1) is the simulation interface electric field intensity distribution graph of the gold modified fluorine-doped indium oxide composite material prepared in Example 5; (b2) is an enlarged view of (b1); (c1) is the simulation interface electric field intensity distribution graph of the gold modified fluorine-doped indium oxide composite material prepared in Example 6; (c2) is an enlarged view of (c1); (d1) is the simulation interface electric field intensity distribution graph of the gold modified fluorine-doped indium oxide composite material prepared in Example 7; (d2) is an enlarged view of (d1). As can be seen from graphs (a1)-(d2), the dark area represents the region where the material interface electric field is enhanced after light irradiation. It can be observed that the sample with the largest gold nanoparticle size has the highest electric field intensity on its surface, which is consistent with the results of the UV diffuse reflectance spectra, indicating that the localized plasmon resonance effect of the gold nanoparticles is affected by the gold nanoparticle size, which is consistent with the change rule of the absorbance.

[0078] Figure 10The simulated interface thermal field intensity distribution diagrams of the fluorine-doped indium oxide materials and the gold-modified fluorine-doped indium oxide composite materials prepared in Examples 1, 3, 5-7 of the present application; wherein (a1) is the simulated interface thermal field intensity distribution diagram of the fluorine-doped indium oxide material prepared in Example 1; (a2) is an enlarged view of (a1); (b1) is the simulated interface thermal field intensity distribution diagram of the gold-modified fluorine-doped indium oxide composite material prepared in Example 3; (b2) is an enlarged view of (b1); (c1) is the simulated interface thermal field intensity distribution diagram of the gold-modified fluorine-doped indium oxide composite material prepared in Example 5; (c2) is an enlarged view of (c1); (d1) is the simulated interface thermal field intensity distribution diagram of the gold-modified fluorine-doped indium oxide composite material prepared in Example 6; (d2) is an enlarged view of (d1); (e1) is the simulated interface thermal field intensity distribution diagram of the gold-modified fluorine-doped indium oxide composite material prepared in Example 7; (e2) is an enlarged view of (e1). As shown in Figures (a1)-(a2), the surface of the fluorine-doped indium oxide material does not have obvious local thermal field enhancement after light irradiation; as shown in Figures (b1)-(e2), the surface thermal field of the material is obviously enhanced after modification with gold nanoparticles, and the enhancement trend is consistent with the electric field intensity distribution rule, which indicates that the local plasmonic resonance effect of the gold nanoparticles can cause the temperature of the material surface to rise, activate the TEA molecules and promote the gas-sensitive reaction to occur.

[0079] Figure 11 The resistance-temperature diagrams of the gold-modified fluorine-doped indium oxide composite materials prepared in Examples 3, 5-7 under different relative humidities and the resistance proportion diagrams of 80% and 30% RH at different temperatures; wherein (a) is the resistance-temperature diagram under different relative humidities; (b) is the resistance proportion diagram. As shown in Figure (a), the baseline resistance of the sensor shows a trend of continuously decreasing with the increase of the working temperature, and with the further increase of the environmental humidity, the baseline resistance of the material also shows a decreasing trend, and the change trend gradually decreases with the increase of the working temperature, which indicates that on the one hand, the excessive activity of the gold nanoparticles can cause the moisture resistance of the material to gradually decrease, and on the other hand, the increase of the working temperature can help to restore the moisture resistance of the material and improve the ability of the material to detect TEA at high temperature; as shown in Figure (b), with the decrease of the particle size of the gold nanoparticles, the moisture stability of the material also gradually decreases, which indicates that the decrease of the particle size of the gold nanoparticles can effectively improve the chemical adsorption activity of the material.

[0080] Figure 12The TEA response value-temperature working curve of the gold modified fluorine-doped indium oxide composite material prepared in Embodiment 3, 5-7 under different relative humidity and the TEA response value ratio curve under 80% and 30% RH at different temperatures; wherein, (a) is the TEA response value-temperature working curve under different relative humidity; (b) is the TEA response value ratio curve. As can be seen from the figure (a), after being modified by the gold nanoparticles, the optimal working temperature of the material for detecting TEA is obviously reduced to 100 ℃, and the performance at high temperature is continuously reduced, which is probably due to that the activity of the gold nanoparticles is too strong, and the reaction activation energy of TEA is effectively reduced, but the activity at high temperature is too strong, resulting in too fast TEA desorption kinetics and insufficient gas sensitivity response; in addition, it can be observed that the sensitivity of the material to TEA under high humidity is obviously reduced; as can be observed from the figure (b), with the continuous reduction of the particle size of the gold nanoparticles, the stability of the sensitivity of the material to TEA under different relative humidity also shows a trend of getting worse with the reduction of the particle size, which indicates that the particle size of the gold nanoparticles is too low to be conducive to the detection of TEA.

[0081] Figure 13 The response recovery curve of the gold modified fluorine-doped indium oxide composite material prepared in Embodiments 5-7 to 100 ppm TEA at 200 ℃ and the response recovery time curve of the gold modified fluorine-doped indium oxide composite material prepared in Embodiments 3, 5-7 to 100 ppm TEA at 200 ℃; wherein, (a) is the response recovery curve; (b) is the response recovery time curve. As can be seen from the figures (a)-(b), the response recovery time change rule of the material to 100 ppm TEA is consistent with the absorbance curve, which confirms that the localized plasmon resonance effect of the gold nanoparticles can effectively accelerate the response recovery rate of TEA, and realize the rapid response and recovery of the TEA gas detection.

[0082] Figure 14 The schematic diagram of the gas sensing element prepared in Embodiment 10. As can be seen from the figure, Figure 14 the gas sensing element includes a ceramic substrate, a gold electrode, four platinum wire leads and a sensing material layer. In the preparation process of the gas sensing element, the prepared gas sensing material is coated on the ceramic substrate, uniformly coated and dried, and then the ceramic substrate is welded on the four-corner base through the four platinum wire leads to obtain the gas sensing element.

[0083] Figure 15The response values of the fluorine-doped indium oxide material, the gold-modified fluorine-doped indium oxide composite material and the fluorine-free doped indium oxide material prepared in Example 1, 6 and Comparative Examples 1, 3 to 100 ppm TEA at 100 ℃. It can be seen that after fluorine doping, the gas sensing performance of the fluorine-doped indium oxide material prepared in Example 1 to TEA is higher than that of the fluorine-free doped indium oxide material prepared in Comparative Example 1, and after modification of gold nanoparticles, the gas sensing performance of the gold-modified fluorine-doped indium oxide composite material prepared in Example 6 is significantly improved; when the particle size of gold nanoparticles is too large, the gas sensing performance is reduced, which shows that the fluorine ion-doped and appropriately sized gold nanoparticle-modified indium oxide material exhibits excellent TEA gas sensing performance.

[0084] Figure 16 The response recovery curve of the gold-modified fluorine-doped indium oxide composite material prepared in Example 3 to 1-100 ppm TEA at 100 ℃. It can be seen from the figure that the gas sensing performance of the material to TEA gradually increases with the increase of the concentration of TEA, showing excellent linear change relationship. In addition, the material shows obvious response value to 1 ppm TEA, and the response value is about 6.34, which shows that the material also shows obvious response to 1 ppm TEA, indicating its ability to accurately identify trace TEA molecules.

[0085] The above only describes the preferred embodiments of the present application and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing a gold-modified fluorine-doped indium oxide composite material, characterized in that, Comprising the following steps: (1) adding indium source, surfactant, alkali source and fluorine source into deionized water, mixing uniformly and then carrying out hydrothermal reaction to obtain indium oxyfluoride precursor, and annealing the indium oxyfluoride precursor to obtain fluorine-doped indium oxide matrix; (2) adding the fluorine-doped indium oxide matrix into deionized water, uniformly dispersing, then adding gold source and mixing uniformly, and then adding dispersant and reducing agent in sequence, stirring and reacting, after the reaction is completed, centrifuging, washing, drying to obtain gold-modified fluorine-doped indium oxide composite material.

2. The production method according to claim 1, wherein In step (1), the fluorine-doped indium oxide matrix is nanorod self-assembled rod bundle-like morphology; And / or, in step (1), the indium source is selected from at least one of indium chloride, indium nitrate, indium acetylacetone or indium acetate; And / or, in step (1), the surfactant is at least one of cetyltrimethylammonium bromide, sodium dodecylbenzenesulfonate, polyvinylpyrrolidone or ascorbic acid; And / or, in step (1), the alkali source is at least one of urea, hexamethylenetetramine, ammonia water or sodium hydroxide; And / or, in step (1), the fluorine source is at least one of sodium fluoride, potassium fluoride, ammonium fluoride or fluorosilicic acid; And / or, in step (1), the molar ratio of the indium source, the surfactant, the alkali source and the fluorine source is 1:2-5:2-8:1-2; And / or, in step (1), the temperature of the hydrothermal reaction is 80-160 ℃, and the time is 8-16 h; And / or, in step (1), the temperature of the annealing treatment is 400-600 ℃, and the time is 1-3 h.

3. The production method according to claim 1, wherein In step (2), the gold source is at least one of gold acetate, sodium chloroaurate, ammonium chloroaurate or chloroauric acid; And / or, in step (2), the dispersant is at least one of L-lysine, cetyltrimethylammonium bromide or tannic acid; And / or, in step (2), the reducing agent is at least one of citric acid, sodium citrate or sodium borohydride; And / or, in step (2), the molar ratio of the fluorine-doped indium oxide matrix, the gold source, the dispersant and the reducing agent is 1:0.01-0.05:5-20:5-20; And / or, in step (2), the time of the stirring reaction is 1-3 h.

4. The gold-modified fluorine-doped indium oxide composite material prepared by the preparation method of any one of claims 1-3.

5. The gold-modified fluorine-doped indium oxide composite of claim 4, wherein the gold-modified fluorine-doped indium oxide composite has a sheet resistance of 1000 ohms / square or less. In the gold-modified fluorine-doped indium oxide composite material, the matrix material is nanorod self-assembled rod bundle-like fluorine-doped indium oxide self-assembled material, and gold is dispersed on the surface of the matrix material in the form of nanoparticles; Or, the diameter of the nanorod self-assembled rod bundle-like fluorine-doped indium oxide is 20-30 nm; Or, the particle size of the gold nanoparticles is 6.8-16.5 nm.

6. A gas sensitive element, characterized by Comprising a substrate, a sensing layer is arranged on the surface of the substrate, and the gas-sensitive material of the sensing layer is the gold-modified fluorine-doped indium oxide composite material of any one of claims 4-5.

7. The method of producing a gas sensor element according to claim 6, wherein Comprising the following steps: mixing the gold-modified fluorine-doped indium oxide composite material of any one of claims 4-5 with a solvent to form a slurry, coating the slurry to the surface of the substrate, and drying to obtain the gas sensor.

8. The production method according to claim 7, wherein The substrate is a ceramic substrate; And / or, the solvent is at least one of deionized water and anhydrous ethanol, preferably deionized water; And / or, the mass ratio of the gold-modified fluorine-doped indium oxide composite material to the solvent is 1:2-6, preferably 1:5; And / or, the substrate is subjected to a drying treatment before the slurry is coated onto the surface of the substrate; the drying temperature is 70-100 ℃, and the drying time is 2-6 min; And / or, the drying temperature after the slurry is coated onto the surface of the substrate is 80-120 ℃, and the drying time is 8-24 h.

9. Use of the gold-modified fluorine-doped indium oxide composite material according to any one of claims 4-5 or the gas sensor according to claim 6 in detecting TEA.

10. Use according to claim 9, wherein the compound is ###0002### The lower limit of the detection of TEA is 1 ppm; and / or, the detection temperature is 100-240 ℃.

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