Pt, pd co-doped in2o3 / tio2 resistance-type hydrogen sensor

Abstract

The application discloses a Pt and Pd co-doped In2O3 / TiO2 resistance type hydrogen sensor, which is composed of an Al2O3 ceramic substrate, interdigital Au electrodes coated on the surface of the Al2O3 ceramic substrate and a gas sensitive thin film coated on the surface of the interdigital Au electrodes; the gas sensitive thin film is made of a PtPd@In2O3 / TiO2 composite material, the In2O3 / TiO2 material is prepared from anhydrous ethanol, anhydrous acetic acid, formamide, tetrabutyl titanate and indium chloride as raw materials through a supercritical drying method and a hydrothermal method. The Pt and Pd co-doping improves the gas sensitive performance of the In2O3 / TiO2 composite material, when the hydrogen sensor is used as a gas sensor, the maximum response of the hydrogen sensor to 2000ppm H2 is 20.7566 at room temperature, the response time is 29s, the recovery time is 41s, and the hydrogen sensor has good selectivity. Therefore, the Pt and Pd co-doped In2O3 / TiO2 resistance type hydrogen sensor has potential to become an excellent room temperature hydrogen sensor.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of preparation and application of hydrogen sensing materials, and particularly relates to a Pt and Pd co-doped In2O3 / TiO2 resistance type hydrogen sensor, a preparation method and application thereof. BACKGROUND

[0002] Hydrogen is colorless and odorless, has the characteristics of high combustion energy and green, and is considered a promising alternative to fossil fuel energy in the future. In addition, hydrogen can meet the application in the fields of power generation, scientific research, methanol industry, petroleum, nuclear power station, chemical fertilizer factory and the like. However, the diffusion coefficient of hydrogen is about 12 times that of natural gas or gasoline, the flame propagation speed is large, and the explosion concentration range is wide. Due to its volatility and high flammability, the storage and transportation of hydrogen are the focus. For safety considerations, a high-quality gas sensor is essential for the safe storage, detection and monitoring of hydrogen. A hydrogen sensor with higher selectivity and high response range can prevent various safety hazards. However, it should be able to function at as low a temperature as possible to minimize the risk of hydrogen explosion, so it is necessary to develop a hydrogen sensor that works at room temperature to detect hydrogen.

[0003] Among many gas sensors, metal oxide (TiO2, In2O3, SnO2, ZnO, etc.) resistance type hydrogen sensors have been widely studied at this stage, but still have the unsatisfactory shortcomings of insufficient sensitivity and poor stability. Even at a lower working temperature, the selectivity is poor and the sensitivity is very low.

[0004] Yasuhisa Naitoh et al. (Sens. Actuators B Chem 2020 321 128525) prepared TiO2 nanotubes by anodic oxidation method, the hollow nanoscale tube wall provides a large specific surface area, and used atomic layer deposition technology to decorate the TiO2 nanotube film with noble metal (Pt) nanoparticles, the working temperature of the device is 300℃, and it is found that in the medium concentration region, gas molecules gradually diffuse into the nanohole. The adsorption on the inner wall surface of the nanopore and the gas diffusion occur simultaneously, the response has a proportional relationship with the deviation of the gas concentration, and the linear relationship of the response is poor.

[0005] Sui et al. (Int. J. Hydrogen Energy 2024 55 855-863) prepared a Pd nanoparticle decorated TiO2 aerogel framework hydrogen sensor, the aerogel structure has a large specific surface area and high porosity, but the device has a working temperature of 325℃, which causes safety risks when detecting hydrogen.

[0006] In the patent application with the application number 202410577281, a heterojunction type In2O3 / TiO2 composite material is obtained by sol-gel method, the composite material has a porous structure, a fast response / recovery time and a high linearity and has a good stability after multiple cycles. However, when it is used as a gas sensor, the high operating temperature poses an explosion risk when detecting hydrogen gas leakage. SUMMARY

[0007] The purpose of the present application is to overcome the shortcomings of the prior art and provide a Pt, Pd co-doped In2O3 / TiO2 resistance type hydrogen sensor. The present application improves the gas sensing performance of In2O3 / TiO2 composite material by Pt, Pd co-doping. When it is used as a gas sensor, the response time is shorter and has good selectivity.

[0008] The purpose of the present application is achieved by the following technical scheme: a Pt, Pd co-doped In2O3 / TiO2 resistance type hydrogen sensor, which is composed of an Al2O3 ceramic substrate, an interdigital Au electrode coated on the surface of the Al2O3 ceramic substrate, and a gas sensitive thin film coated on the surface of the interdigital Au electrode; the gas sensitive thin film is made of PtPd@In2O3 / TiO2 composite material, and the PtPd@In2O3 / TiO2 composite material is prepared by the following steps:

[0009] (1) Anhydrous acetic acid and tetrabutyl titanate are added to anhydrous ethanol and stirred to make them uniformly mixed into a solution A containing anhydrous acetic acid and tetrabutyl titanate, and the volume ratio of anhydrous acetic acid, tetrabutyl titanate and anhydrous ethanol is 2-10:15-20:20-50;

[0010] Anhydrous acetic acid, deionized water and formamide are added to anhydrous ethanol and stirred to make them uniformly mixed into a solution B containing anhydrous acetic acid, deionized water and formamide, and the volume ratio of anhydrous acetic acid, deionized water, formamide and anhydrous ethanol is 2-10:1-5:0.1-2:10-20;

[0011] (2) Solution B is added to solution A and stirred until it is uniformly mixed to obtain a gel precursor solution, and the gel precursor solution is placed in a thermostat to obtain a wet gel; the wet gel is aged by solvent exchange, then the wet gel is soaked in ethanol, and the blocky TiO2 aerogel is obtained by supercritical drying;

[0012] (3) adding indium nitrate and dilute hydrochloric acid solution into deionized water, stirring, the ratio between the mass of indium nitrate, the volume of dilute hydrochloric acid and the volume of deionized water being 0.1-1:1-10:10-20; adding blocky TiO2 aerogel into ammonia water, stirring, the ratio between the mass of blocky TiO2 aerogel and the volume of ammonia water being 0.5-3:5-10; then mixing the two solutions, transferring the mixed solution into a reaction kettle for hydrothermal treatment, centrifuging the white precipitate, washing with ethanol and drying to obtain a white powder;

[0013] (4) placing the white powder in step (3) into a porcelain boat, placing the porcelain boat in a tube furnace, calcining in an air atmosphere, and collecting light yellow In2O3 / TiO2 powder;

[0014] (5) taking the light yellow In2O3 / TiO2 powder, adding into deionized water, ultrasonic stirring, and collecting to obtain In2O3 / TiO2 dispersion A, the ratio between the mass of light yellow In2O3 / TiO2 powder and the volume of deionized water being 0.1-5:10-30;

[0015] measuring chloroplatinic acid, palladium chloride and dilute hydrochloric acid, adding into deionized water, ultrasonic stirring at room temperature to obtain orange yellow liquid B; the ratio between the mass of chloroplatinic acid, the mass of palladium chloride, the volume of dilute hydrochloric acid and the volume of deionized water being 0.5-5:0.5-5:2-10:10-20;

[0016] adding L-ascorbic acid into deionized water to configure transparent solution C; the ratio between the mass of L-ascorbic acid and the volume of deionized water being 0.176-0.528:10-30;

[0017] (6) adding the orange yellow liquid B and the transparent solution C obtained in step (5) into dispersion A in sequence to obtain orange yellow mixed liquid, stirring and aging at room temperature to obtain PtPd@In2O3 / TiO2 mixed liquid;

[0018] (7) centrifuging the black precipitate obtained from the PtPd@In2O3 / TiO2 mixed liquid to obtain a first material, placing the first material into a porcelain boat, placing the porcelain boat in a tube furnace, calcining in an air atmosphere, collecting black powder of PtPd@In2O3 / TiO2 composite to obtain a second material, i.e. PtPd@In2O3 / TiO2 composite material.

[0019] In step (3), the hydrothermal treatment is specifically 10-12h at 120-150℃; in steps (3) and (7), the drying is specifically 12-24h at 60-80℃.

[0020] The length of the Al2O3 ceramic substrate is 18-25 mm, and the width is 5-10 mm; the length of the interdigital Au electrode is 8-10 mm, the width is 4-6 mm, and the line width is 45-50 mu m; and the thickness of the gas sensitive thin film is 150-200 mu m.

[0021] Another object of the present application is to provide a preparation method of a Pt, Pd co-doped In2O3 / TiO2 composite material resistance type hydrogen sensor, which is prepared by using the above material, and the specific preparation steps are as follows:

[0022] (1) The PtPd@In2O3 / TiO2 composite material is mixed with anhydrous ethanol at a mass ratio of 2-8:1, and is ground into a paste-like slurry; and the slurry is coated on the surface of the interdigital Au electrode;

[0023] (2) The device obtained in (1) is aged at 200-350 DEG C for 4-12 h, so as to obtain the Pt, Pd co-doped In2O3 / TiO2 composite material resistance type hydrogen sensor.

[0024] The Pt, Pd co-doped In2O3 / TiO2 composite material resistance type hydrogen sensor of the present application is applied to hydrogen detection.

[0025] The present application has the following advantages:

[0026] (1) The present application realizes rapid detection of hydrogen at room temperature through the electronic sensitization effect of Pt and Pd and the n-n heterojunction formed between TiO2 and In2O3, and solves the safety problem caused by the high working temperature of the existing hydrogen-sensitive material.

[0027] (2) The present application improves the gas sensing performance of the In2O3 / TiO2 composite material by co-doping Pt and Pd, and when used as a gas sensor, the maximum response of the hydrogen sensor to 2000 ppm H2 at room temperature is 20.7566, the response time is 29 s, the recovery time is 41 s, and it has good selectivity. Therefore, the Pt, Pd co-doped In2O3 / TiO2 resistance type hydrogen sensor prepared in the present application has the potential to become an excellent room temperature hydrogen sensor. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 The dynamic response curves of the composite materials of the present example and the control group to 100-2000 ppm H2 at room temperature are shown in the following table:

[0029] Figure 2 The 5 cycles of Example 3 to 500 ppm hydrogen at room temperature are shown in the following table:

[0030] Figure 3 The selectivity of the composite materials of the present example and the control group to various gases is shown in the following table. DETAILED DESCRIPTION

[0031] The application provides a resistance type gas sensor for hydrogen detection, comprising an electrode sheet and a gas sensitive layer attached to the electrode sheet; the gas sensitive layer is made of PtPd@In2O3 / TiO2 material, the In2O3 / TiO2 material is prepared from anhydrous ethanol, anhydrous acetic acid, formamide and tetrabutyl titanate and indium chloride as raw materials by a supercritical drying method and a hydrothermal method. The technical scheme of the application is further described below.

[0032] The resistance type hydrogen sensor provided by the application is composed of an Al2O3 ceramic substrate, interdigital Au electrodes coated on the surface of the Al2O3 ceramic substrate and a gas sensitive thin film coated on the surface of the interdigital Au electrodes; the gas sensitive thin film is made of PtPd@In2O3 / TiO2 composite material, and the PtPd@In2O3 / TiO2 composite material is prepared by the following steps:

[0033] (1) anhydrous acetic acid and tetrabutyl titanate are added to anhydrous ethanol and stirred to uniformly mix to form a solution A containing anhydrous acetic acid and tetrabutyl titanate, and the volume ratio of the anhydrous acetic acid, tetrabutyl titanate and anhydrous ethanol is 2-10:15-20:20-50;

[0034] (2) anhydrous acetic acid, deionized water and formamide are added to anhydrous ethanol and stirred to uniformly mix to form a solution B containing anhydrous acetic acid, deionized water and formamide, and the volume ratio of the anhydrous acetic acid, deionized water, formamide and anhydrous ethanol is 2-10:1-5:0.1-2:10-20;

[0035] (2) solution B is added to solution A and stirred to uniformly mix to obtain a gel precursor solution, and the gel precursor solution is placed in a thermostat to obtain a wet gel; the wet gel is aged by solvent exchange, then the wet gel is soaked in ethanol, and the blocky TiO2 aerogel is obtained by supercritical drying;

[0036] (3) indium nitrate and dilute hydrochloric acid solution are added to deionized water and stirred, and the ratio of the mass of indium nitrate, the volume of dilute hydrochloric acid and the volume of deionized water is 0.1-1:1-10:10-20; the blocky TiO2 aerogel is added to ammonia water and stirred, and the ratio of the mass of the blocky TiO2 aerogel and the volume of ammonia water is 0.5-3:5-10; then the two solutions are mixed, and the mixed solution is transferred to a reaction kettle for hydrothermal treatment; the white precipitate is separated by centrifugation, washed with ethanol and dried to obtain a white powder; the hydrothermal treatment is specifically carried out at 120-150℃ for 10-12h, and the drying is specifically carried out at 60-80℃ for 12-24h.

[0037] (4) the white powder in step (3) is put into a porcelain boat, the porcelain boat is placed in a tube furnace, and calcination is carried out in an air atmosphere, and a light yellow In2O3 / TiO2 powder is collected; the calcination is specifically: calcination at 400-600 DEG C for 2-5 h.

[0038] (5) the light yellow In2O3 / TiO2 powder is taken and added into deionized water, ultrasonic stirring is carried out for 10-20 min, and an In2O3 / TiO2 dispersion A is collected; the ratio between the mass of the light yellow In2O3 / TiO2 powder and the volume of the deionized water is 0.1-5:10-30;

[0039] chloroplatinic acid, palladium chloride and dilute hydrochloric acid are weighed and added into deionized water, ultrasonic stirring is carried out at room temperature for 10-20 min, and an orange yellow liquid B is obtained; the ratio between the mass of the chloroplatinic acid, the mass of the palladium chloride, the volume of the dilute hydrochloric acid and the volume of the deionized water is 0.5-5:0.5-5:2-10:10-20;

[0040] L-ascorbic acid is added into deionized water, and a transparent solution C is configured; the ratio between the mass of the L-ascorbic acid and the volume of the deionized water is 0.176-0.528:10-30;

[0041] (6) the orange yellow liquid B and the transparent solution C obtained in (5) are sequentially added into the dispersion A, an orange yellow mixed liquid is obtained, stirring and aging are carried out at room temperature, and a PtPd@In2O3 / TiO2 mixed liquid is obtained;

[0042] (7) the black precipitate obtained by centrifugation of the PtPd@In2O3 / TiO2 mixed liquid is washed with deionized water for multiple times, is put into an oven for drying, and a first material is obtained; the drying is specifically: drying at 60-80 DEG C for 12-24 h; the first material is put into a porcelain boat, the porcelain boat is placed in a tube furnace, and calcination is carried out in an air atmosphere, and a black powder of a PtPd@In2O3 / TiO2 composite is collected,

[0043] a second material is obtained, and the second material is a PtPd@In2O3 / TiO2 composite material; the calcination is specifically: calcination at 260-280 DEG C for 2-4 h.

[0044] The length of the Al2O3 ceramic substrate is 18-25 mm, the width is 5-10 mm; the length of the interdigital Au electrode is 8-10 mm, the width is 4-6 mm, and the line width is 45-50 mu m; and the thickness of the gas sensitive thin film is 150-200 mu m.

[0045] The application further provides a preparation method of a Pt, Pd co-doped In2O3 / TiO2 composite material resistance type hydrogen gas sensor.

[0046] (1) PtPd@In2O3 / TiO2 composite material is mixed with anhydrous ethanol in a mass ratio of 2-8:1, and grinded into a paste-like slurry; the slurry is coated on the surface of an interdigital Au electrode (i.e. Au-coated alumina electrode);

[0047] (2) The device obtained in (1) is aged at 200-350℃ for 4-12h, thereby obtaining a resistance type hydrogen gas sensor of Pt, Pd co-doped In2O3 / TiO2 composite material.

[0048] The resistance type hydrogen gas sensor of Pt, Pd co-doped In2O3 / TiO2 composite material of the application is applied to hydrogen detection.

[0049] The effect of the resistance type gas sensor of the application is further verified by specific examples, control groups and drawings.

[0050] Example 1:

[0051] The example provides a resistance type hydrogen gas sensor of Pt, Pd co-doped In2O3 / TiO2, and the specific preparation steps are as follows:

[0052] (1) Preparation of nano In2O3 / TiO2:

[0053] S1. 10ml of anhydrous ethanol, 2ml of anhydrous acetic acid and 10ml of tetrabutyl titanate are weighed into a beaker and stirred to mix uniformly into a solution A; 10ml of anhydrous ethanol, 2ml of anhydrous acetic acid, 1ml of deionized water and 0.1ml of DMF are weighed into a beaker and stirred to mix uniformly into a solution B; solution B is added to solution A and stirred, and the obtained gel precursor solution is placed in a thermostat after uniform stirring; the wet gel is aged after solvent exchange, the wet gel is soaked with ethanol, and blocky TiO2 aerogel is obtained after supercritical drying;

[0054] S2. The wet gel is soaked with ethanol, and the soaking is replaced every 6-10 hours for more than 4 times to obtain an In2O3 / TiO2 composite precursor; preparation: 0.5g of indium nitrate, 20ml of deionized water, 5ml of dilute hydrochloric acid solution and 10ml of ammonia water are weighed into a beaker and stirred to mix uniformly to obtain a mixed solution, and the blocky TiO2 aerogel is added to the mixed solution. The mixed solution is transferred to a reaction kettle for hydrothermal reaction, cooled to room temperature, washed with deionized water and dried to obtain white powder.

[0055] S3. The white powder in step S2 is weighed and placed in a porcelain boat, the porcelain boat is placed in a tube furnace and calcined in an air atmosphere, and after natural cooling, light yellow In2O3 / TiO2 powder is collected.

[0056] (2) Preparation of Pt0Pd1@In2O3 / TiO2:

[0057] S1. Weigh 200 mg of In2O3 / TiO2 powder into a beaker, drop in an appropriate amount of deionized water, and ultrasonically stir for 10 min. Collect In2O3 / TiO2 dispersion A.

[0058] S2. Weigh 1 mg of chloroplatinic acid, 1 mg of palladium chloride, 10 ml of deionized water, and 5 ml of 0.01 mol / L dilute hydrochloric acid, and ultrasonically stir for 20 min at room temperature to make them uniformly mixed, obtaining orange-yellow liquid B.

[0059] S3. Weigh 0.5 g of L-ascorbic acid and 30 ml of deionized water, and stir for 10 min at room temperature to make them uniformly mixed, obtaining transparent solution C.

[0060] S4. Drop solution B into dispersion A, and stir at room temperature to make them uniformly mixed, obtaining orange-yellow mixed liquid; drop solution C into the mixed liquid, and the color of the mixed liquid immediately changes to gray-brown. Stir and age at room temperature for 22 h, obtaining PtPd@In2O3 / TiO2 precursor liquid.

[0061] S5. Centrifuge the aged precursor liquid to obtain black precipitate, wash with deionized water for multiple times, and place in an oven for drying at 80℃, obtaining first material. Place the first material in a porcelain boat, and place the porcelain boat in a tube furnace for calcination at 350℃ in an air atmosphere for 3 h. After natural cooling, collect Pt0Pd1@In2O3 / TiO2 powder. In the powder, the mass ratio of Pt compound to In2O3 / TiO2 is 1 / 98, and the mass ratio of Pd compound to In2O3 / TiO2 is 1 / 98.

[0062] Example 2: This example provides a Pt, Pd co-doped In2O3 / TiO2 resistance type hydrogen sensor, which is different from example 1 only in that the ratio of chloroplatinic acid, palladium chloride, deionized water, and 0.01 mol / L dilute hydrochloric acid in step (2) is 2 mg:1 mg:10 ml:5 ml; in the powder, the mass ratio of Pt compound to In2O3 / TiO2 is 2 / 97, and the mass ratio of Pd compound to In2O3 / TiO2 is 1 / 97. The remaining steps remain unchanged.

[0063] Example 3: This example provides a Pt, Pd co-doped In2O3 / TiO2 resistance type hydrogen sensor, which is different from example 1 only in that the ratio of chloroplatinic acid, palladium chloride, deionized water, and 0.01 mol / L dilute hydrochloric acid in step (2) is 1 mg:2 mg:10 ml:5 ml; in the powder, the mass ratio of Pt compound to In2O3 / TiO2 is 1 / 97, and the mass ratio of Pd compound to In2O3 / TiO2 is 2 / 97. The remaining steps remain unchanged.

[0064] Control group 1: a resistance-type hydrogen sensor, the only difference from Example 1 is that the ratio of chloroplatinic acid, palladium chloride, deionized water, 0.01 mol / L dilute hydrochloric acid is 0 mg: 1 mg: 10 ml: 5 ml; in the black powder, the mass ratio of Pd compound to In2O3 / TiO2 is 1 / 99, respectively. The remaining steps remain the same.

[0065] Control group 2: a resistance-type hydrogen sensor, the only difference from Example 1 is that in step (2), the ratio of chloroplatinic acid, palladium chloride, deionized water, 0.01 mol / L dilute hydrochloric acid is 1 mg: 0 mg: 10 ml: 5 ml; in the powder, the mass ratio of Pt compound to In2O3 / TiO2 is 1 / 99, respectively. The remaining steps remain the same.

[0066] The gas-sensitive performance test method for hydrogen is as follows:

[0067] Take 5 mg of the prepared light yellow powder and grind it with ethanol to form a uniform paste. Then coat the obtained slurry on the surface of the interdigital electrode (i.e. Au-coated alumina electrode) to form a thin layer, in order to improve the stability of the sensing layer. First, pass high-purity air until the resistance value of the test electrode stabilizes at Ra, then pass the target gas (mixed H2) of a certain concentration until the resistance value stabilizes at Rg, the response value is Ra / Rg, the larger the ratio, the greater the decrease in the resistance value of the electrode in hydrogen. The hydrogen sensing performance is measured in a multi-channel tester using dynamic gas flow, the dynamic response curve to 100 ppm-2000 ppm hydrogen is tested, the dynamic response-recovery curve is tested; the cyclic response to 500 ppm hydrogen is tested; the selectivity to ethanol, methanol, ammonia, propylene glycol, and hydrogen is tested.

[0068] Figure 1 The dynamic response curve of the composite material of the example and the control group to 100-2000 ppm H2 at room temperature. The dynamic response curve and the response value curve with concentration change can know the following points:

[0069] (1) The resistance of the PtPd@In2O3 / TiO2 sensor decreases after hydrogen is introduced, and the resistance increases after air is introduced, indicating that its response to hydrogen at room temperature is n-type response.

[0070] (2) The maximum response value of the sensor of Example 3 (Pt1Pd2@In2O3 / TiO2) after introducing 2000 ppm hydrogen is 20.7566, the response time is 29 s, and the recovery time is 41 s, indicating that it has a good response to hydrogen at room temperature.

[0071] (3) The response of Example 3 (Pt1Pd2@In2O3 / TiO2) to 500 ppm hydrogen gas is 6.11, which is 5.41 times the response value (1.13) of Example 1 (Pt0Pd1@In2O3 / TiO2).

[0072] Figure 2 For 5 cycles of Pt1Pd2@In2O3 / TiO2 (Example 3) at room temperature to 500 ppm hydrogen gas, from Figure 2 It can be seen that the repeatability of the material is good, and it is also stable at room temperature.

[0073] Figure 3 For the selectivity of the examples and the control group to various gases, from Figure 3 The response value of Example 3 (Pt1Pd2@In2O3 / TiO2) to 500 ppm gas is: hydrogen (6.11), ethanol (1.08), ammonia (1.33), propylene glycol (1.43), methanol (1.076), and Example 3 has good selectivity to hydrogen.

[0074] Those skilled in the art will realize that the examples described herein are for the purpose of helping the reader understand the principles of the present application, and should be understood as not limiting the scope of protection of the present application to such specific statements and examples. Those skilled in the art can make various other specific modifications and combinations according to the technical inspiration disclosed in the present application without departing from the essence of the present application, and these modifications and combinations are still within the scope of protection of the present application.

Claims

1. A resistance-type hydrogen sensor of Pt and Pd co-doped In2O3 / TiO2, which is composed of an Al2O3 ceramic substrate, interdigital Au electrodes coated on the surface of the Al2O3 ceramic substrate, and a gas sensitive thin film coated on the surface of the interdigital Au electrodes; characterized in that, The gas sensitive thin film is made of PtPd@In2O3 / TiO2 composite material, and the PtPd@In2O3 / TiO2 composite material is prepared by the following steps: (1) anhydrous acetic acid and tetrabutyl titanate are added into anhydrous ethanol to stir and mix uniformly to form a solution A containing anhydrous acetic acid and tetrabutyl titanate, and the volume ratio of anhydrous acetic acid, tetrabutyl titanate and anhydrous ethanol is 2-10: 15-20: 20-50; anhydrous acetic acid, deionized water and formamide are added into anhydrous ethanol to stir and mix uniformly to form a solution B containing anhydrous acetic acid, deionized water and formamide, and the volume ratio of anhydrous acetic acid, deionized water, formamide and anhydrous ethanol is 2-10: 1-5: 0.1-2: 10-20; (2) solution B is added into solution A to stir and mix uniformly to obtain a gel precursor solution, and the gel precursor solution is placed in a thermostat to obtain a wet gel; the wet gel is aged by solvent exchange, then the wet gel is soaked in ethanol, and the blocky TiO2 aerogel is obtained by supercritical drying; (3) indium nitrate and dilute hydrochloric acid solution are added into deionized water to stir, and the ratio of the mass of indium nitrate, the volume of dilute hydrochloric acid and the volume of deionized water is 0.1-1: 1-10: 10-20; the blocky TiO2 aerogel is added into ammonia water to stir, and the ratio of the mass of the blocky TiO2 aerogel and the volume of ammonia water is 0.5-3: 5-10; then the two solutions are mixed, and the mixed solution is transferred into a reaction kettle for hydrothermal treatment; the white precipitate is centrifuged, washed with ethanol and dried to obtain a white powder; (4) the white powder in step (3) is placed in a porcelain boat, and the porcelain boat is placed in a tube furnace for calcination in an air atmosphere to collect light yellow In2O3 / TiO2 powder; (5) the light yellow In2O3 / TiO2 powder is taken and added into deionized water to ultrasonically stir to obtain In2O3 / TiO2 dispersion A, and the ratio of the mass of the light yellow In2O3 / TiO2 powder and the volume of deionized water is 0.1-5: 10-30; platinic chloride, palladium chloride and dilute hydrochloric acid are weighed and added into deionized water to ultrasonically stir at room temperature to obtain orange yellow liquid B; the ratio of the mass of platinic chloride, the mass of palladium chloride, the volume of dilute hydrochloric acid and the volume of deionized water is 0.5-5: 0.5-5: 2-10: 10-20; L-ascorbic acid is added into deionized water to prepare transparent solution C; the ratio of the mass of L-ascorbic acid and the volume of deionized water is 0.176-0.528: 10-30; (6) the orange yellow liquid B and the transparent solution C obtained in step (5) are sequentially added into the dispersion A to obtain an orange yellow mixed liquid, which is stirred and aged at room temperature to obtain a PtPd@In2O3 / TiO2 mixed liquid. (7) centrifuging the black precipitate obtained from the PtPd@In2O3 / TiO2 mixed solution to obtain a black precipitate, washing the black precipitate with deionized water for multiple times, and placing the black precipitate in an oven to dry to obtain a first material; placing the first material in a porcelain boat, placing the porcelain boat in a tube furnace, and calcining in an air atmosphere to collect black powder of the PtPd@In2O3 / TiO2 composite to obtain a second material, i.e., the PtPd@In2O3 / TiO2 composite material.

2. The Pt, Pd co-doped In203 / Ti02 resistive hydrogen sensor of claim 1, wherein, In the step (3), the hydrothermal treatment is specifically 10-12 h at 120-150 ℃; and in the step (3) and the step (7), the drying is specifically 12-24 h at 60-80 ℃.

3. The Pt, Pd co-doped In203 / Ti02 resistive hydrogen sensor of claim 1, wherein, In the step (4), the calcining is specifically 2-5 h at 400-600 ℃; and in the step (7), the calcining is specifically 2-4 h at 260-280 ℃.

4. The Pt, Pd co-doped In203 / Ti02 resistive hydrogen sensor of claim 1, wherein, The Al2O3 ceramic substrate has a length of 18-25 mm and a width of 5-10 mm; the interdigital Au electrode has a length of 8-10 mm, a width of 4-6 mm, and a line width of 45-50 μm; and the gas sensitive thin film has a thickness of 150-200 μm.

5. A preparation method of a Pt, Pd co-doped In2O3 / TiO2 resistance-type hydrogen sensor, which is prepared by using the material used in the sensor according to any one of claims 1-4, and the specific preparation steps are as follows: (1) mixing the PtPd@In2O3 / TiO2 composite material with anhydrous ethanol at a mass ratio of 2-8:1, and grinding into a paste-like slurry; and coating the slurry on the surface of the interdigital Au electrode; (2) aging the device obtained in the step (1) at 200-350 ℃ for 4-12 h to obtain a Pt, Pd co-doped In2O3 / TiO2 composite material resistance-type hydrogen sensor.

6. The Pt, Pd co-doped In2O3 / TiO2 resistance-type hydrogen sensor according to any one of claims 1-4, which is applied to hydrogen detection.

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