A core-shell structure TiO2 / In2O3 coaxial nanofiber material and a preparation method and application thereof

Abstract

The application discloses a kind of core-shell structure TiO2 / In2O3 coaxial nanofiber materials and preparation method and application thereof, it is related to gas sensor technical field, comprising the following steps: (1) isopropyl titanate and polyacrylonitrile are dissolved in solvent, shell layer spinning solution is obtained;(2) four point five hydrated indium nitrate and polyvinylpyrrolidone are dissolved in solvent, core layer spinning solution is obtained;(3) shell layer spinning solution and core layer spinning solution are carried out coaxial electrospinning, precursor with core-shell structure is obtained;(4) precursor with core-shell structure is calcined in the atmosphere of air, and core-shell structure TiO2 / In2O3 coaxial nanofiber material is obtained.The application develops a kind of gas-sensitive material with improved sensitive effect to triethylamine, with high sensitivity, good selectivity and high stability, has wide application prospect in the field such as environment and food safety.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of gas sensor, more particularly, to a core-shell structure TiO2 / In2O3 coaxial nanofiber material and a preparation method and application thereof. BACKGROUND

[0002] The rapid development of national industry has brought great changes to people's life, but at the same time, environmental problems have become increasingly serious, and automobile exhaust, industrial waste gas and the like have brought great hidden dangers to people's health. Triethylamine is a volatile organic compound with strong ammonia smell. When the human body is exposed to triethylamine atmosphere for a long time, it will have a serious impact on health, such as skin allergy, respiratory system damage and eye irritation. In addition, triethylamine is also considered to be a carcinogen, which may promote the growth and spread of cancer cells. Due to the strong volatility of triethylamine and the low concentration in the air, etc., it leads to the increase of detection difficulty, and special attention should be paid to sampling methods and analysis techniques and the like. Therefore, it is of great importance to quickly, accurately and real-time monitor triethylamine for human health and environmental safety.

[0003] Metal oxide semiconductors (MOSs) have broad application prospects in triethylamine detection due to their excellent physical and chemical properties. So far, various MOSs, such as In2O3, TiO2, WO3, NiO, have been used to prepare triethylamine gas sensors. Among them, In2O3 and TiO2 are widely concerned due to their advantages of small toxicity, high electron mobility and morphological diversity. However, the gas sensors prepared by single In2O3 or TiO2 have the disadvantages of poor selectivity, low sensitivity, long response / recovery time, etc., which limit their wide application.

[0004] Therefore, it is necessary to develop a gas sensitive material with improved sensitive effect for triethylamine, so as to overcome the problems of poor selectivity, low sensitivity, poor stability, slow response, etc. in the detection of triethylamine by existing gas sensors. SUMMARY

[0005] The present application aims to overcome the above-mentioned defects in the prior art, and provides a core-shell structure TiO2 / In2O3 coaxial nanofiber material and a preparation method and application thereof, which provides a feasible method for detecting the concentration of triethylamine gas in the environment.

[0006] In order to improve the above-mentioned defects, the applicant finds that the strategies of constructing heterojunction, regulating morphology, loading noble metal, etc. can be expected to improve the gas sensing performance. Among them, the heterojunction is an interface region produced by the contact of materials with different Fermi levels. Due to the difference of the energy band structure of the sensing material, when the Fermi level reaches equilibrium, the energy band bending produces an electron depletion layer or a hole accumulation layer, which controls the band gap of the metal oxide. More specifically, the construction of the heterojunction can provide more active sites for the target gas, showing higher catalytic activity than single metal oxide. Therefore, the construction of the heterojunction has great significance for improving the gas sensing performance of the metal oxide. In addition, the applicant finds that the core-shell structure can provide a special electron transfer path. When a material with a small work function is selected as the core, electrons will transfer from the core to the shell, and the accumulation of electrons in the shell is conducive to the formation of a space charge layer, thereby improving the sensing performance.

[0007] Therefore, the present application adopts the coaxial electrospinning method to prepare the core-shell structure TiO2 / In2O3 coaxial nanofiber material, constructs the n-n heterojunction, and improves the triethylamine sensing performance of TiO2 and In2O3. On the one hand, the core-shell structure provides a special electron transport channel, which is conducive to accelerating the gas adsorption-desorption process; on the other hand, the formation of the n-n heterojunction improves the synergistic effect between the two materials, so that they integrate the advantages of each other and improve the gas sensing performance of the material. The sensor prepared by the present application is effective and has practical significance for dynamic monitoring of triethylamine.

[0008] In order to achieve the above-mentioned purpose, the technical scheme of the present application is as follows:

[0009] A preparation method of a core-shell structure TiO2 / In2O3 coaxial nanofiber material, comprising the following steps:

[0010] (1) Dissolving titanium isopropoxide and polyacrylonitrile in a solvent to obtain a yellow shell layer spinning solution;

[0011] (2) Dissolving indium nitrate pentahydrate and polyvinylpyrrolidone in a solvent to obtain a colorless transparent core layer spinning solution;

[0012] (3) Coaxial electrospinning the shell layer spinning solution and the core layer spinning solution to obtain a precursor with a core-shell structure;

[0013] (4) Calcining the precursor with the core-shell structure in an air atmosphere to obtain the core-shell structure TiO2 / In2O3 coaxial nanofiber material;

[0014] The core layer of the core-shell structure TiO2 / In2O3 coaxial nanofiber material is In2O3, and the shell layer is TiO2. The mass ratio of the core layer to the shell layer is 1: (2-3).

[0015] Optionally, in step (1), the solvent is N,N-dimethylformamide; the mass-volume ratio of the isopropyl titanate, the polyacrylonitrile and the N,N-dimethylformamide is 0.25-0.75 g: 1.0-1.2 g: 10-20 mL.

[0016] Optionally, in step (2), the solvent is N,N-dimethylformamide; the mass-volume ratio of the indium nitrate tetrahydrate, the polyvinylpyrrolidone and the N,N-dimethylformamide is 0.25-0.5 g: 1.0-1.2 g: 10-20 mL.

[0017] Optionally, in step (1), the dissolving is carried out under stirring, and the stirring time is 10-12 h; in step (2), the dissolving is carried out under stirring, and the stirring time is 10-12 h.

[0018] Optionally, in step (3), the voltage for the coaxial electrospinning is 15-20 kV; the inner diameter of the outer needle head for the coaxial electrospinning is 0.26-0.86 mm, and the outer diameter is 0.58-1.26 mm; the inner diameter of the inner needle head for the coaxial electrospinning is 0.26-0.86 mm, and the outer diameter is 0.58-1.26 mm; the inner push speed of the microsyringe pump for the coaxial electrospinning is 0.0002-0.001 mm / s, and the outer push speed is 0.0002-0.001 mm / s; the distance between the needle head and the receiver is 10-15 cm; the ambient temperature for the coaxial electrospinning is 25-30℃, and the ambient humidity is 35-40% RH.

[0019] Optionally, in step (4), the heating rate for the calcination is 1-2℃ / min; the temperature for the calcination is 550-600℃; and the time for the calcination is 1.5-2 h.

[0020] The application further discloses a core-shell structure TiO2 / In2O3 coaxial nanofiber material prepared by the preparation method.

[0021] Optionally, the diameter of the core-shell structure TiO2 / In2O3 coaxial nanofiber material is 200-400 nm.

[0022] The application further discloses application of the core-shell structure TiO2 / In2O3 coaxial nanofiber material prepared by the preparation method to a triethylamine gas sensor, and the gas sensitive material of the triethylamine gas sensor is the core-shell structure TiO2 / In2O3 coaxial nanofiber material.

[0023] Optionally, the application method comprises the following steps: adding the core-shell structure TiO2 / In2O3 coaxial nanofiber material into deionized water, grinding for 10 minutes to obtain a suspension; smearing the suspension on an Al2O3 ceramic tube, naturally drying, welding the obtained Al2O3 ceramic tube and a heating wire on a gas sensitive element base to obtain the triethylamine gas sensor.

[0024] The application has the following beneficial effects:

[0025] (1) The application uses indium nitrate pentahydrate and isopropyl titanate as raw materials, polyvinylpyrrolidone and polyacrylonitrile as carriers, and N,N-dimethylformamide as a solvent to prepare core layer spinning solution and shell layer spinning solution respectively; then the core layer spinning solution and the shell layer spinning solution are coaxially electrospun to obtain TiO2 / In2O3 coaxial nanofiber precursor, and then the TiO2 / In2O3 coaxial nanofiber precursor is calcined in air to obtain the core-shell structure TiO2 / In2O3 coaxial nanofiber material; and the application further improves the performance of the coaxial nanofiber by regulating the core-shell mass ratio.

[0026] (2) The application introduces TiO2 / In2O3 heterojunction to improve the defects of single metal oxide semiconductor material triethylamine gas sensor, such as high working temperature, low response value, poor selectivity, etc. The response value of the application to 200ppm of triethylamine gas is as high as 250.8 at 280℃, the response and recovery time is short (14 / 21s), the detection line is low (13.5ppb), and the stability and repeatability are good. The application still has a high response value under high humidity, which meets the market demand for high sensitivity and high humidity environment of the gas sensor.

[0027] (3) The application uses coaxial electrospinning technology to realize one-step synthesis of the core-shell structure coaxial nanofiber, and improves the traditional multi-step synthesis method of the core-shell structure nanomaterial. The synthesized nanomaterial has a clear core-shell structure, a clear interface layer can be observed, and no impurities are observed. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 Fig. 3 is an SEM image of the TiO2 / In2O3 gas sensitive material prepared in Example 3 of the application.

[0029] Figure 2is a response value graph of the TiO2 / In2O3 gas sensitive material prepared in Example 3 of the present application.

[0030] Figure 3 is a TEM graph of the TiO2 / In2O3 gas sensitive material prepared in Example 3 of the present application. DETAILED DESCRIPTION

[0031] The present application is further described below in conjunction with specific examples, but the present application is not limited in any way by the examples.

[0032] Example 1

[0033] The preparation method of the core-shell structure TiO2 / In2O3 coaxial nanofiber material of the present example comprises the following steps:

[0034] (1) Dissolve 0.25 g of isopropyl titanate and 1.2 g of polyacrylonitrile in 10 mL of N,N-dimethylformamide, and stir for 12 h to obtain a yellow shell layer spinning solution.

[0035] (2) Dissolve 0.5 g of indium nitrate tetrahydrate and 1.0 g of polyvinylpyrrolidone in 10 mL of N,N-dimethylformamide, and stir for 12 h to obtain a colorless transparent core layer spinning solution.

[0036] (3) Coaxial electrospinning of the shell layer spinning solution and the core layer spinning solution, the voltage of the coaxial electrospinning is 20 kV; the outer needle of the coaxial electrospinning device is a metal needle, the inner diameter of the outer needle is 0.86 mm, and the outer diameter is 1.26 mm; the inner diameter of the inner needle is 0.26 mm, and the outer diameter is 0.58 mm; the inner push speed of the microsyringe pump used for coaxial electrospinning is 0.0002 mm / s, and the outer push speed is 0.001 mm / s; the distance between the needle and the receiver is 15 cm; the environmental temperature of the coaxial electrospinning is 25℃, and the environmental humidity is 35% RH; after the spinning is completed, collect the Ti1In2 coaxial nanofiber precursor on the aluminum foil.

[0037] (4) In an air atmosphere, calcine the Ti1In2 coaxial nanofiber precursor at 550℃ for 2 h at a heating rate of 1℃ / min, to obtain a core-shell structure Ti1In2 coaxial nanofiber material.

[0038] The core-shell structure Ti1In2 coaxial nanofiber material prepared in the present example has a core layer of In2O3 and a shell layer of TiO2, and the shell-core mass ratio Ti:In = 1:2.

[0039] The core-shell structure Ti1In2 coaxial nanofiber material prepared in the embodiment is applied to a gas sensitive material of a triethylamine gas sensor, including: adding the core-shell structure Ti1In2 coaxial nanofiber material into a proper amount of deionized water, and grinding for 10 min to obtain a suspension; smearing the suspension on an Al2O3 ceramic tube, and after natural air drying, welding the obtained Al2O3 ceramic tube and a heating wire on a gas sensitive element base to obtain the triethylamine gas sensor.

[0040] It is detected that the working temperature of the core-shell structure Ti1In2 coaxial nanofiber gas sensor is 280℃; the response recovery time is 17 / 28 s; the response value to 200 ppm triethylamine is 32.3; the stability is 11.5%; and the minimum detection limit is 21.2 ppb.

[0041] Embodiment 2

[0042] The preparation method of the core-shell structure TiO2 / In2O3 coaxial nanofiber material of the embodiment includes the following steps:

[0043] (1) 0.25 g of isopropyl titanate and 1.2 g of polyacrylonitrile are dissolved in 10 ml of N,N-dimethylformamide, and stirred for 12 h to obtain a yellow shell layer spinning solution.

[0044] (2) 0.25 g of indium nitrate tetrahydrate and 1.0 g of polyvinylpyrrolidone are dissolved in 10 ml of N,N-dimethylformamide, and stirred for 12 h to obtain a colorless transparent core layer spinning solution.

[0045] (3) The core-shell coaxial electrospinning is performed on the shell layer spinning solution and the core layer spinning solution, the voltage of the coaxial electrospinning is 20 kV; the outer needle head of the coaxial electrospinning device is a metal needle head, the inner diameter of the outer needle head is 0.86 mm, and the outer diameter is 1.26 mm; the inner diameter of the inner needle head is 0.26 mm, and the outer diameter is 0.58 mm; the inner push speed of the micro-injection pump for the coaxial electrospinning is 0.0002 mm / s, and the outer push speed is 0.001 mm / s; the distance between the needle head and the receiver is 15 cm; the environmental temperature of the coaxial electrospinning is 25℃, and the environmental humidity is 35% RH; after the spinning is completed, the Ti1In1 coaxial nanofiber precursor on the aluminum foil paper is collected.

[0046] (4) In an air atmosphere, the Ti1In1 coaxial nanofiber precursor is calcined at 550℃ for 2 h at a temperature rising rate of 1℃ / min to obtain the core-shell structure Ti1In2 coaxial nanofiber material.

[0047] The core-shell structure Ti1In1 coaxial nanofiber material prepared in the embodiment has a core layer of In2O3 and a shell layer of TiO2, and the shell-core mass ratio Ti:In = 1:1.

[0048] The core-shell structure Ti1In1 coaxial nanofiber material prepared in the embodiment is applied to a gas sensitive material of a triethylamine gas sensor, including: adding the core-shell structure Ti1In1 coaxial nanofiber material into a proper amount of deionized water, and grinding for 10 minutes to obtain a suspension; smearing the suspension on an Al2O3 ceramic tube, and after natural air drying, welding the obtained Al2O3 ceramic tube and a heating wire on a gas sensitive element base to obtain the triethylamine gas sensor.

[0049] It is detected that the working temperature of the core-shell structure Ti1In1 coaxial nanofiber gas sensor is 280℃; the response recovery time is 16 / 27s; the response value to 200ppm triethylamine is 47.5; the stability is 14.1%; and the minimum detection limit is 42.8ppb.

[0050] Embodiment 3

[0051] The preparation method of the core-shell structure TiO2 / In2O3 coaxial nanofiber material of the embodiment includes the following steps:

[0052] (1) 0.5g of isopropyl titanate and 1.2g of polyacrylonitrile are dissolved in 10ml of N,N-dimethylformamide, and stirring is performed for 12h to obtain a yellow shell layer spinning solution.

[0053] (2) 0.25g of indium nitrate pentahydrate and 1.0g of polyvinylpyrrolidone are dissolved in 10ml of N,N-dimethylformamide, and stirring is performed for 12h to obtain a colorless transparent core layer spinning solution.

[0054] (3) The shell layer spinning solution and the core layer spinning solution are subjected to coaxial electrospinning, the voltage of the coaxial electrospinning is 20kV; the outer needle head of the coaxial electrospinning device is a metal needle head, the inner diameter of the outer needle head is 0.86mm, and the outer diameter is 1.26mm; the inner diameter of the inner needle head is 0.26mm, and the outer diameter is 0.58mm; the inner push speed of the microsyringe pump used for the coaxial electrospinning is 0.0002mm / s, and the outer push speed is 0.001mm / s; the distance between the needle head and the receiver is 15cm; the environmental temperature of the coaxial electrospinning is 25℃, and the environmental humidity is 35%RH; after the spinning is completed, the Ti2In1 coaxial nanofiber precursor on the aluminum foil paper is collected.

[0055] (4) In an air atmosphere, the Ti2In1 coaxial nanofiber precursor is calcined at 550℃ at a temperature increasing rate of 1℃ / min for 2h to obtain the core-shell structure Ti2In1 coaxial nanofiber material.

[0056] The core-shell structure Ti2In1 coaxial nanofiber material prepared in the embodiment has a core layer of In2O3 and a shell layer of TiO2, and the shell-core mass ratio Ti:In = 2:1.

[0057] The core-shell structure Ti2In1 coaxial nanofiber material prepared in the embodiment is applied to a gas sensitive material of a triethylamine gas sensor, including: adding the core-shell structure Ti2In1 coaxial nanofiber material into a proper amount of deionized water, and grinding for 10 min to obtain a suspension; smearing the suspension on an Al2O3 ceramic tube, and after natural air drying, welding the obtained Al2O3 ceramic tube and a heating wire on a gas sensitive element base to obtain the triethylamine gas sensor.

[0058] It is detected that the working temperature of the core-shell structure Ti2In1 coaxial nanofiber gas sensor is 280℃; the response recovery time is 14 / 21 s; the response value to 200 ppm triethylamine is 250.8; the stability is 5.1%; and the minimum detection limit is 13.5 ppb.

[0059] Embodiment 4

[0060] The preparation method of the core-shell structure TiO2 / In2O3 coaxial nanofiber material of the embodiment includes the following steps:

[0061] (1) Dissolving 0.75 g of isopropyl titanate and 1.2 g of polyacrylonitrile in 10 ml of N,N-dimethylformamide to obtain a yellow shell layer spinning solution after stirring for 12 h.

[0062] (2) Dissolving 0.25 g of indium nitrate pentahydrate and 1.0 g of polyvinylpyrrolidone in 10 ml of N,N-dimethylformamide to obtain a colorless transparent core layer spinning solution after stirring for 12 h.

[0063] (3) Coaxial electrospinning the shell layer spinning solution and the core layer spinning solution, the voltage of the coaxial electrospinning is 20 kV; the outer needle head of the coaxial electrospinning device is a metal needle head, the inner diameter of the outer needle head is 0.86 mm, and the outer diameter is 1.26 mm; the inner diameter of the inner needle head is 0.26 mm, and the outer diameter is 0.58 mm; the inner push speed of the microsyringe pump for coaxial electrospinning is 0.0002 mm / s, and the outer push speed is 0.001 mm / s; the distance between the needle head and the receiver is 15 cm; the environmental temperature of the coaxial electrospinning is 25℃, and the environmental humidity is 35% RH; after the spinning is completed, the Ti3In1 coaxial nanofiber precursor on the aluminum foil paper is collected.

[0064] (4) In an air atmosphere, calcining the Ti3In1 coaxial nanofiber precursor at 550℃ for 2 h at a temperature rising rate of 1℃ / min to obtain the core-shell structure Ti3In1 coaxial nanofiber material.

[0065] The core-shell structure Ti3In1 coaxial nanofiber material prepared in the embodiment, the core layer is In2O3, the shell layer is TiO2, and the shell core mass ratio Ti:In = 3:1.

[0066] The core-shell structure Ti3In1 coaxial nanofiber material prepared in the embodiment is applied to a gas sensitive material of a triethylamine gas sensor, including: the core-shell structure Ti3In1 coaxial nanofiber material is added into a proper amount of deionized water, and a suspension is obtained after grinding for 10 min; the suspension is applied on an Al2O3 ceramic tube, and after natural air drying, the obtained Al2O3 ceramic tube and a heating wire are welded on a gas sensitive element base to obtain a triethylamine gas sensor.

[0067] It is detected that the working temperature of the core-shell structure Ti3In1 coaxial nanofiber gas sensor is 300℃; the response recovery time is 18 / 24 s; the response value to 200 ppm triethylamine is 129.6; the stability is 8.9%; and the minimum detection limit is 15.8 ppb.

[0068] Comparative Example 1

[0069] The comparative example is compared with the embodiment 3, and the difference is that the gas sensitive material of the gas sensor of the comparative example does not have a core-shell structure, but only a single TiO2.

[0070] Comparative Example 2

[0071] The comparative example is compared with the embodiment 3, and the difference is that the gas sensitive material of the gas sensor of the comparative example does not have a core-shell structure, but only a single In2O3.

[0072] Comparative Example 3

[0073] The comparative example is compared with the embodiment 3, and the difference is that the fiber material of the comparative example is a material prepared by electrospinning, in which the core layer is TiO2 and the shell layer is In2O3.

[0074] Comparative Example 4

[0075] The comparative example is compared with the embodiment 3, and the difference is that the mass ratio of the shell core of the gas sensitive material of the gas sensor of the comparative example is Ti:In = 1:3.

[0076] Examples 5-8

[0077] The embodiment is compared with the embodiment 3, and the difference is that the voltage of the coaxial electrospinning in step (3) is changed. Except the above difference, other operations are the same, and details are not repeated here. The voltage of the coaxial electrospinning in the examples 5-8 is controlled to be 10 kV, 15 kV, 18 kV and 25 kV.

[0078] Examples 9-12

[0079] The embodiment is different from the embodiment 3 in that the calcination temperature in step (4) is changed, and other operations are the same except the above difference, which will not be repeated here; the calcination temperature in the embodiments 9-12 is controlled to be 480℃, 580℃, 600℃, and 610℃.

[0080] Embodiments 13-16

[0081] The embodiment is different from the embodiment 3 in that the heating rate of calcination in step (4) is changed, and other operations are the same except the above difference, which will not be repeated here; the calcination temperature in the embodiments 13-16 is controlled to be 0.5℃ / min, 1.5℃ / min, 2℃ / min, and 2.5℃ / min.

[0082] Table 1 Performance detection table of core-shell structure TiO2 / In2O3 coaxial nanofiber gas sensor

[0083]

[0084] As shown in Table 1, the sensing performance of the material is improved by regulating the morphology of the TiO2 / In2O3 coaxial nanofiber gas sensitive material and the means of constructing a heterojunction, and then the best performance of the TiO2 / In2O3 composite material is explored by controlling the core-shell raw material ratio and the parameters of the preparation process. The construction of the heterojunction and the unique coaxial nanofiber structure provide a large number of active sites, greatly exert the synergistic effect and electronic effect of the material, greatly improve the sensitivity and stability of the gas sensor, and reduce the minimum detection limit of the material.

[0085] As Figure 1 shown, the TiO2 / In2O3 coaxial nanofiber prepared by the application has a diameter of 200-400nm, and the performance of the coaxial nanofiber is further improved by regulating the core-shell mass ratio.

[0086] As shown in Table 1 and Figure 2 It can be seen that the Ti2 / In1 gas sensor prepared in the embodiment 3 has the best performance, the response value to 200ppm triethylamine is 250.8, the working temperature is low (280℃), the fluctuation rate is only 5.1%, indicating that the stability is good, the detection limit is low (13.5ppb), and the application prospect in the field of gas sensors is good, which improves the defects of single metal oxide semiconductor material triethylamine gas sensor such as high working temperature, low response value, and poor selectivity. Under high humidity, there is still a high response value, which meets the market demand for high sensitivity and high humidity environment of gas sensors.

[0087] As Figure 3It can be known that the coaxial electrostatic spinning technology is used to realize one-step synthesis of the coaxial nanofiber with core-shell structure.

[0088] The above-mentioned embodiments only express several embodiments of the present application, and the description is more specific and detailed, but it cannot be understood as the limitation of the patent application scope. It should be pointed out that for ordinary skilled in the art, without departing from the concept of the present application, several modifications and improvements can be made, which belong to the protection scope of the present application. Therefore, the protection scope of the present application patent should be subject to the appended claims.

Claims

1. A method for preparing a core-shell structure TiO2 / In2O3 coaxial nanofiber material, characterized in that, The method comprises the following steps: (1) dissolving isopropyl titanate and polyacrylonitrile in a solvent to obtain a shell spinning solution; (2) dissolving indium nitrate pentahydrate and polyvinylpyrrolidone in a solvent to obtain a core spinning solution; (3) performing coaxial electrospinning on the shell spinning solution and the core spinning solution to obtain a precursor with a core-shell structure; the voltage of the coaxial electrospinning is 15 kV-20 kV; (4) calcining the precursor with the core-shell structure in an air atmosphere to obtain the core-shell structure TiO2 / In2O3 coaxial nanofiber material; the heating rate of the calcining is 1 ℃ / min-2 ℃ / min; the temperature of the calcining is 550 ℃-600 ℃. The core layer of the core-shell structure TiO2 / In2O3 coaxial nanofiber material is In2O3, and the shell layer is TiO2; the mass ratio of the core layer to the shell layer is 1:(2-3).

2. The method for preparing core-shell structured TiO2 / In2O3 coaxial nanofibers according to claim 1, characterized in that, In step (1), the solvent is N,N-dimethylformamide; The mass-volume ratio of the isopropyl titanate, the polyacrylonitrile and the N,N-dimethylformamide is 0.25-0.75 g:1.0-1.2 g:10-20 mL.

3. The method for preparing core-shell structured TiO2 / In2O3 coaxial nanofibers according to claim 1, characterized in that, In step (2), the solvent is N,N-dimethylformamide; The mass-volume ratio of the indium nitrate pentahydrate, the polyvinylpyrrolidone and the N,N-dimethylformamide is 0.25-0.5 g:1.0-1.2 g:10-20 mL.

4. The method for preparing core-shell structured TiO2 / In2O3 coaxial nanofibers according to claim 1, characterized in that, In step (1), the dissolving is performed under stirring, and the stirring time is 10 h-12 h; In step (2), the dissolving is performed under stirring, and the stirring time is 10 h-12 h.

5. The method for preparing core-shell structured TiO2 / In2O3 coaxial nanofibers according to claim 1, characterized in that, In step (3), the inner diameter of the outer needle head for the coaxial electrospinning is 0.26 mm-0.86 mm, and the outer diameter is 0.58 mm-1.26 mm; the inner diameter of the inner needle head for the coaxial electrospinning is 0.26 mm-0.86 mm, and the outer diameter is 0.58 mm-1.26 mm; the inner push speed of the microsyringe pump for the coaxial electrospinning is 0.0002 mm / s-0.001 mm / s, and the outer push speed is 0.0002 mm / s-0.001 mm / s; the distance between the needle head and the receiver is 10 cm-15 cm; the environmental temperature for the coaxial electrospinning is 25 ℃-30 ℃, and the environmental humidity is 35%RH-40%RH.

6. The method for preparing core-shell structured TiO2 / In2O3 coaxial nanofibers according to claim 1, characterized in that, In step (4), the calcining time is 1.5 h-2 h.

7. A core-shell structured TiO2 / In2O3 coaxial nanofiber material prepared according to the preparation method of any one of claims 1-6, characterized in that, The core layer of the core-shell structure TiO2 / In2O3 coaxial nanofiber material is In2O3, and the shell layer is TiO2; the mass ratio of the core layer to the shell layer is 1:(2-3).

8. The core-shell structured TiO2 / In2O3 coaxial nanofiber material according to claim 7, characterized by The diameter of the core-shell structure TiO2 / In2O3 coaxial nanofiber material is 200 nm-400 nm.

9. Use of the core-shell structured TiO2 / In2O3 coaxial nanofiber material prepared according to the preparation method of any one of claims 1-6 in a triethylamine gas sensor, characterized in that, The gas-sensitive material of the triethylamine gas sensor is the core-shell structure TiO2 / In2O3 coaxial nanofiber material.

10. Use according to claim 9, characterized in that, The method comprises the following steps: The core-shell structure TiO2 / In2O3 coaxial nanofiber material is added into deionized water, and a suspension is obtained after grinding. The suspension is applied on an Al2O3 ceramic tube, and after natural air drying, the obtained Al2O3 ceramic tube and heating wire are welded on a gas sensitive element base to obtain the triethylamine gas sensor.

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