A hydrogen-sensitive material and a preparation method thereof, a hydrogen-sensitive sensor and a preparation method and application thereof

Abstract

The application provides a hydrogen-sensitive material and a preparation method thereof, a hydrogen-sensitive sensor and a preparation method and application thereof, and belongs to the technical field of hydrogen-sensitive materials. The hydrogen-sensitive material comprises a Ti3C2 / TiO2 heterojunction and palladium nanoparticles loaded on the surface of the Ti3C2 / TiO2 heterojunction. The application adopts the Ti3C2 / TiO2 heterojunction to load the palladium nanoparticles to form a three-phase heterojunction, so that the transmission of charges is accelerated, the sensitivity and response speed are greatly improved under the excitation of ultraviolet and infrared light, and the hydrogen-sensitive sensor can respond to hydrogen at room temperature. The results of the examples show that the hydrogen-sensitive sensor prepared from the hydrogen-sensitive material provided by the application has a hydrogen sensitivity of 69.9% at room temperature, and a response time of 16s.

Description

Technical Field

[0001] This invention belongs to the field of hydrogen-sensitive materials technology, specifically relating to a hydrogen-sensitive material and its preparation method, a hydrogen-sensitive sensor and its preparation method and application. Background Technology

[0002] Hydrogen energy boasts advantages such as high calorific value, renewability, and cleanliness, making it currently the only new energy source that simultaneously meets the requirements of resource conservation, environmental protection, and sustainable development. According to the "China Hydrogen Energy Industry Development Report 2020," by 2050, hydrogen energy is projected to be widely used in transportation, energy storage, industry, and construction, with the hydrogen energy industry chain exceeding 10 trillion yuan in value. At that time, the entire country will enter a hydrogen energy society. However, due to hydrogen's extremely low density compared to other gases, it is highly susceptible to leakage in various processes. Furthermore, hydrogen is highly prone to explosion when its volume concentration in the air reaches 4% to 75.6%. Because hydrogen is colorless and odorless, leaks are often undetectable. Therefore, highly sensitive and fast-response hydrogen sensors are essential for constantly monitoring the hydrogen content in the air during hydrogen production and use to ensure daily safety.

[0003] The key to high-performance sensors lies in hydrogen-sensitive materials. Noble metals palladium, nickel, and platinum, as well as their composites, are commonly used as active materials in hydrogen sensors. Early research has shown that at 1 atm pressure, hydrogen molecules react more readily with palladium than with nickel and platinum. Furthermore, palladium has attracted widespread attention due to its good conductivity and high stability. Current technologies often combine palladium nanoparticles with inorganic carbon materials such as carbon nanotubes, graphene, and MXene to improve sensing performance. However, existing materials operate at temperatures above 300°C and exhibit poor sensitivity and response speed. Therefore, there is an urgent need for a hydrogen-sensitive material with a low operating temperature, high sensitivity, and fast response speed. Summary of the Invention

[0004] The purpose of this invention is to provide a hydrogen-sensitive material and its preparation method, a hydrogen-sensitive sensor and its preparation method, and its applications. The hydrogen-sensitive material provided by this invention can respond to hydrogen gas at room temperature and exhibits high sensitivity and fast response speed.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] The present invention provides a hydrogen-sensitive material comprising a Ti3C2 / TiO2 heterojunction and palladium nanoparticles loaded on the surface of the Ti3C2 / TiO2 heterojunction.

[0007] Preferably, the palladium nanoparticles have a particle size of 4–6 nm.

[0008] This invention provides a method for preparing the hydrogen-sensitive material described in the above technical solution, comprising the following steps:

[0009] (1) Titanium carbide was annealed to obtain a Ti3C2 / TiO2 heterojunction;

[0010] (2) The Ti3C2 / TiO2 heterojunction obtained in step (1) is mixed with water to obtain a Ti3C2 / TiO2 heterojunction suspension;

[0011] (3) The Ti3C2 / TiO2 heterojunction suspension obtained in step (2) is mixed and dried to obtain a hydrogen-sensitive material.

[0012] Preferably, the annealing temperature in step (1) is 350–650°C.

[0013] Preferably, the annealing time in step (1) is 0.5 to 1.5 hours.

[0014] Preferably, in step (3), the mass ratio of Ti3C2 / TiO2 heterojunction in the Ti3C2 / TiO2 heterojunction suspension to palladium nanoparticles in the palladium nanoparticle suspension is (8-10):1.

[0015] The present invention provides a hydrogen-sensitive sensor, including an interdigitated electrode and an active material layer deposited on the interdigitated electrode, wherein the active material in the active material layer includes the hydrogen-sensitive material described in the above technical solution or the hydrogen-sensitive material prepared according to the preparation method described in the above technical solution.

[0016] Preferably, it further includes a ZIF-8 metal-organic framework material layer deposited outside the active material layer.

[0017] This invention provides a method for preparing the hydrogen-sensitive sensor described above, comprising the following steps:

[0018] a. Deposit active material on the interdigitated electrode to obtain an interdigitated electrode with an active material layer deposited on it;

[0019] b. Immerse the interdigitated electrode with the active material layer obtained in step a in ZIF-8 solution to obtain a hydrogen sensor.

[0020] The present invention also provides the application of the hydrogen sensor described in the above technical solution or the hydrogen sensor prepared according to the preparation method described in the above technical solution in hydrogen detection.

[0021] This invention provides a hydrogen-sensitive material comprising a Ti3C2 / TiO2 heterojunction and palladium nanoparticles loaded on the surface of the Ti3C2 / TiO2 heterojunction. This invention utilizes a Ti3C2 / TiO2 heterojunction loaded with palladium nanoparticles to form a three-phase heterojunction. This structure enables accelerated charge transport, significantly improving sensitivity and response speed under ultraviolet and infrared light excitation, and allowing it to respond to hydrogen at room temperature. Results from the embodiments show that the hydrogen-sensitive sensor prepared from the hydrogen-sensitive material provided by this invention achieves a sensitivity of 69.9% to hydrogen at room temperature, with a response time of 16 s. Detailed Implementation

[0022] The present invention provides a hydrogen-sensitive material comprising a Ti3C2 / TiO2 heterojunction and palladium nanoparticles loaded on the surface of the Ti3C2 / TiO2 heterojunction.

[0023] In this invention, the particle size of the palladium nanoparticles is preferably 4-6 nm, more preferably 5 nm. By limiting the particle size of the palladium nanoparticles to the above range, this invention enables them to have a larger specific surface area, thereby further improving the sensing performance.

[0024] This invention employs a Ti3C2 / TiO2 heterojunction to support palladium nanoparticles to form a three-phase heterojunction. This structure enables accelerated charge transport. Furthermore, the introduction of TiO2 significantly enhances the sensitivity and response speed under ultraviolet and infrared light excitation, and allows it to respond to hydrogen at room temperature.

[0025] The present invention also provides a method for preparing the hydrogen-sensitive material described in the above technical solution, comprising the following steps:

[0026] (1) Titanium carbide was annealed to obtain a Ti3C2 / TiO2 heterojunction;

[0027] (2) The Ti3C2 / TiO2 heterojunction obtained in step (1) is mixed with water to obtain a Ti3C2 / TiO2 heterojunction suspension;

[0028] (3) The Ti3C2 / TiO2 heterojunction suspension obtained in step (2) is mixed and dried to obtain a hydrogen-sensitive material.

[0029] Unless otherwise specified, the present invention does not have any special limitation on the source of the raw materials, and products prepared by commercially available products or conventional preparation methods known to those skilled in the art are acceptable.

[0030] This invention involves annealing titanium carbide to obtain a Ti3C2 / TiO2 heterojunction.

[0031] In this invention, the titanium carbide is preferably titanium carbide nanosheets.

[0032] In this invention, the method for preparing the titanium carbide nanosheets preferably includes the following steps:

[0033] 1) Ti3AlC2 powder was mixed with lithium fluoride and hydrochloric acid to carry out an etching reaction, resulting in multilayer titanium carbide;

[0034] 2) Mix the multilayer titanium carbide obtained in step 1) with water, and then perform ultrasonication and centrifugation to obtain titanium carbide nanosheets.

[0035] In this invention, Ti3AlC2 powder is preferably mixed with lithium fluoride and hydrochloric acid to carry out an etching reaction to obtain multilayer titanium carbide.

[0036] In this invention, the concentration of the hydrochloric acid is preferably 5-7 mol / L, more preferably 6 mol / L.

[0037] In this invention, the mass ratio of Ti3AlC2 powder to hydrochloric acid is preferably 1g:(30-50)mL, more preferably 1g:40mL.

[0038] In this invention, the mass ratio of Ti3AlC2 powder to lithium fluoride is preferably 1:(1-2), more preferably 1:(1.5-2).

[0039] In this invention, the etching reaction temperature is preferably 30–40°C; the etching reaction time is preferably 36–72 h, more preferably 48 h; and the etching reaction is preferably carried out under stirring conditions. This invention does not impose any special limitations on the stirring method or rate; stirring techniques well-known to those skilled in the art can be used.

[0040] In this invention, during the etching reaction, hydrochloric acid and lithium fluoride remove Al from the Ti3AlC2 powder to obtain a two-dimensional layered titanium carbide material. This invention limits the amount of each raw material, the etching reaction temperature, and the time to the aforementioned ranges, thus enabling more thorough removal of Al while preserving its two-dimensional layered structure.

[0041] After the etching reaction is completed, the present invention preferably performs acid washing, water washing, centrifugation and drying on the product of the etching reaction in sequence to obtain multilayer titanium carbide.

[0042] In this invention, the solution used for pickling is preferably hydrochloric acid; the concentration of the hydrochloric acid is preferably 0.5–1.5 mol / L, more preferably 1 mol / L. In this invention, the pickling is used to remove lithium fluoride. This invention does not limit the amount of solution used or the number of pickling cycles; amounts and cycles well known to those skilled in the art can be used.

[0043] The present invention does not impose any special limitations on the operation of water washing and centrifugation, and any water washing and centrifugation technical solutions known to those skilled in the art can be used.

[0044] In this invention, the drying temperature is preferably 50-80°C, more preferably 60-70°C; the drying time is preferably 8-24 hours, more preferably 12-18 hours.

[0045] After obtaining multilayer titanium carbide, the present invention preferably mixes the multilayer titanium carbide with water and performs ultrasonication and centrifugation in sequence to obtain titanium carbide nanosheets.

[0046] In this invention, the mass ratio of the multilayer titanium carbide to the volume ratio of water is preferably 1-3 mg: 1 mL.

[0047] In this invention, the power of the ultrasound is preferably 100-150W, more preferably 120W; the duration of the ultrasound is preferably 0.5-1.5h, more preferably 1h.

[0048] In this invention, the centrifugation rate is preferably 3000-4000 rpm, more preferably 3500 rpm; the centrifugation time is preferably 0.5-1.5 h, more preferably 1 h.

[0049] In this invention, the ultrasound can exfoliate multilayer titanium carbide to obtain single-layer titanium carbide nanosheets. This invention limits the power and duration of the ultrasound within the aforementioned range, enabling more thorough exfoliation of the multilayer titanium carbide.

[0050] After centrifugation, the product of centrifugation is preferably dried and ground sequentially to obtain titanium carbide nanosheets.

[0051] The present invention does not impose any special limitations on the drying operation; any drying technique known to those skilled in the art can be used.

[0052] In this invention, the mesh size of the milled titanium carbide nanosheets is preferably ≥400 mesh. This invention does not impose any special limitations on the milling operation; any milling technique well-known to those skilled in the art can be used to ensure that the mesh size of the milled titanium carbide nanosheets is within the above-mentioned range.

[0053] The preparation method of the present invention can completely remove Al from Ti3AlC2 and completely exfoliate multilayer titanium carbide, thereby increasing the specific surface area of ​​titanium carbide nanosheets and improving their sensing performance.

[0054] In this invention, the annealing temperature is preferably 350–650°C, more preferably 400–600°C, and most preferably 450–550°C; the annealing time is preferably 0.5–1.5 h, more preferably 1 h. In this invention, the annealing is preferably performed under vacuum. In this invention, the surface of the titanium carbide nanosheets contains O and OH groups, which break during the annealing process, thereby reacting with the titanium in the titanium carbide to generate titanium dioxide in situ, resulting in a Ti3C2 / TiO2 heterojunction. By limiting the annealing temperature and time to the above ranges, this invention can adjust the titanium dioxide content in the heterojunction, thereby adjusting the sensing performance of the hydrogen-sensitive material.

[0055] After obtaining the Ti3C2 / TiO2 heterojunction, the present invention mixes the Ti3C2 / TiO2 heterojunction with water to obtain a Ti3C2 / TiO2 heterojunction suspension.

[0056] In this invention, the concentration of the Ti3C2 / TiO2 heterojunction suspension is preferably 0.5 to 1.5 mg / mL, more preferably 1 mg / mL.

[0057] In this invention, the mixing of the Ti3C2 / TiO2 heterojunction and water is preferably ultrasonic; the ultrasonic power is preferably 100-150W, more preferably 120W; and the ultrasonic time is preferably 20-40min, more preferably 30min.

[0058] After obtaining the Ti3C2 / TiO2 heterojunction suspension, the present invention mixes the Ti3C2 / TiO2 heterojunction suspension with a palladium nanoparticle suspension to obtain a hydrogen-sensitive material.

[0059] In this invention, the preferred method for preparing palladium nanoparticles in the palladium nanoparticle suspension is as follows: 17.7 mg of PdCl2 is dissolved in 6 mol / L HCl to prepare 0.05 mol / L H2PdCl4; 10 ml of ethylene glycol and 0.13 g of polyvinylpyrrolidone (PVP) are dissolved in the H2PdCl4 solution; 0.1 mol / L NaOH solution is added to adjust the pH to 11; the reaction is carried out at 80°C for 2 hours; the product is washed twice with deionized water and ethanol; and dried at 40°C for 12 hours to obtain palladium nanoparticles.

[0060] In this invention, the solvent in the palladium nanoparticle suspension is preferably water.

[0061] In this invention, the concentration of the palladium nanoparticle suspension is preferably 0.5 to 1.5 mg / mL, more preferably 1 mg / mL.

[0062] In this invention, the mixing of the Ti3C2 / TiO2 heterojunction suspension and the palladium nanoparticle suspension is preferably ultrasonic; the ultrasonic power is preferably 100-150W, more preferably 120W; and the ultrasonic time is preferably 20-40min, more preferably 30min.

[0063] In this invention, the preferred mass ratio of the Ti3C2 / TiO2 heterojunction in the Ti3C2 / TiO2 heterojunction suspension to the palladium nanoparticles in the palladium nanoparticle suspension is (8-10):1, more preferably 9:1. By limiting the mass ratio of the Ti3C2 / TiO2 heterojunction in the Ti3C2 / TiO2 heterojunction suspension to the palladium nanoparticles in the palladium nanoparticle suspension within the above range, this invention can adjust the content of each component in the hydrogen-sensitive material, allowing the palladium nanoparticles to be more uniformly loaded onto the surface of the Ti3C2 / TiO2 heterojunction, thereby further improving its sensing performance.

[0064] After mixing, the present invention preferably filters and dries the mixed product in sequence to obtain a hydrogen-sensitive material.

[0065] The present invention does not impose any special limitations on the filtration and drying operations; any filtration and drying techniques well known to those skilled in the art can be used.

[0066] This invention generates a Ti3C2 / TiO2 heterojunction in situ by annealing titanium carbide nanosheets, and then loads palladium nanoparticles to form a three-phase heterojunction, thereby accelerating charge transport. Under ultraviolet and infrared light excitation, the sensitivity and response speed are greatly improved, and it can respond to hydrogen at room temperature. By controlling the amount of each raw material, reaction temperature, time and other process parameters, the sensing performance of the hydrogen-sensitive material can be further improved.

[0067] The present invention also provides a hydrogen-sensitive sensor, including an interdigitated electrode and an active material layer deposited on the interdigitated electrode, wherein the active material in the active material layer includes the hydrogen-sensitive material described in the above technical solution or the hydrogen-sensitive material prepared according to the preparation method described in the above technical solution.

[0068] The hydrogen sensor provided by this invention can respond to hydrogen at room temperature, and has high sensitivity and fast response speed.

[0069] In this invention, the hydrogen sensor preferably further includes a ZIF-8 metal-organic framework material layer deposited outside the active material layer.

[0070] In this invention, the ZIF-8 metal-organic framework material layer can improve the selectivity of the hydrogen sensor for hydrogen.

[0071] This invention provides a method for preparing the hydrogen-sensitive sensor described in the preferred embodiment above, comprising the following steps:

[0072] a. Deposit active material on the interdigitated electrode to obtain an interdigitated electrode with an active material layer deposited on it;

[0073] b. Immerse the interdigitated electrode with the active material layer obtained in step a in ZIF-8 solution to obtain a hydrogen sensor.

[0074] The present invention deposits an active material on an interdigital electrode to obtain an interdigital electrode with an active material layer deposited on it.

[0075] In this invention, the deposition is preferably performed by drop-coating a suspension of active material onto the interdigitated electrode.

[0076] In this invention, the mixture obtained by mixing the Ti3C2 / TiO2 heterojunction suspension and the palladium nanoparticle suspension during the preparation of the hydrogen-sensitive material described in the above technical solution is directly drop-coated onto the interdigitated electrode.

[0077] In this invention, the surface area of ​​the interdigital electrode is preferably 0.5 cm². 2 In this invention, the volume of the active material suspension during drop coating is preferably 40–60 μL, more preferably 50 μL. By limiting the volume of the active material suspension during drop coating to the above range, this invention can adjust the thickness of the active material layer and improve its sensing performance.

[0078] After obtaining the interdigitated electrode with the active material layer deposited, the present invention immerses the interdigitated electrode with the active material layer deposited in ZIF-8 solution to obtain a hydrogen sensor.

[0079] In this invention, the preferred method for preparing the ZIF-8 solution is as follows: 216 mg Zn(AC)2·2H2O and 15 mL 2-methylimidazole are dissolved in 30 mL methanol, stirred at room temperature for 24 hours, filtered, dried, and then dissolved in 30 mL methanol to obtain the ZIF-8 solution.

[0080] In this invention, the amount of ZIF-8 solution is preferably sufficient to cover the interdigitated electrode with the active material layer deposited on it.

[0081] In this invention, the impregnation time is preferably 0.5 to 5 hours. By controlling the impregnation time, this invention can adjust the porosity between ZIF-8 atoms in the ZIF-8 metal-organic framework material layer, allowing only hydrogen atoms to enter, thereby improving the selectivity of the hydrogen-sensitive material.

[0082] After impregnation, the present invention preferably washes and dries the impregnated electrodes in sequence to obtain a hydrogen sensor.

[0083] The present invention does not impose any special limitations on the washing and drying operations; any washing and drying technical solutions known to those skilled in the art can be used.

[0084] The present invention also provides the application of the hydrogen sensor described in the above technical solution or the hydrogen sensor prepared according to the preparation method described in the above technical solution in hydrogen detection.

[0085] The present invention does not impose any special limitations on the operation of the hydrogen sensor in hydrogen detection; any technical solution for the application of hydrogen sensor in hydrogen detection that is well known to those skilled in the art can be used.

[0086] The hydrogen sensor provided by this invention can respond to hydrogen at room temperature, and has high sensitivity, fast response speed, and excellent selectivity for hydrogen.

[0087] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0088] Example 1

[0089] In this embodiment, the hydrogen-sensitive material consists of a Ti3C2 / TiO2 heterojunction and palladium nanoparticles loaded on the surface of the Ti3C2 / TiO2 heterojunction; the particle size of the palladium nanoparticles is 5 nm.

[0090] The preparation method is as follows:

[0091] (1) 1.6 g LiF was slowly dissolved in 40 mL of 6 mol / L HCl and stirred for 15 min to ensure complete dissolution. 1 g Ti3AlC2 (the mass ratio of Ti3AlC2 to lithium fluoride was 1:1.6) was slowly added and stirred at 35 °C for 48 hours. The etched solution was first washed twice with HCl (1 mol / L) to remove excess LiF, and then washed with deionized water and centrifuged at 3500 rpm for 5 min each time, for a total of 7 centrifugations to make the pH of the solution greater than 6. The precipitate was collected and finally placed in a vacuum drying oven and dried at 60 °C for 12 hours to obtain multilayer titanium carbide. The obtained multilayer titanium carbide was added to deionized water (the mass ratio of multilayer titanium carbide to water was 2 mg:1 mL) and ultrasonicated at 120 W for 1 h. The mixture was then centrifuged at 3500 rpm for 1 hour and titanium carbide nanosheets (400 mesh) were collected by filtration, drying and grinding.

[0092] (2) Add titanium carbide nanosheets into a tube furnace and anneal at 350°C for 1 h in a vacuum environment to obtain Ti3C2 / TiO2 heterojunction;

[0093] (3) Dissolve 17.7 mg of PdCl2 in 6 mol / L HCl to prepare 0.05 mol / L H2PdCl4. Dissolve 10 ml of ethylene glycol and 0.13 g of polyvinylpyrrolidone (PVP) in the H2PdCl4 solution. Add 0.1 mol / L NaOH solution to adjust the pH to 11. React at 80 °C for 2 hours. Wash the product twice with deionized water and ethanol. Dry at 40 °C for 12 hours to obtain palladium nanoparticles.

[0094] (4) The Ti3C2 / TiO2 heterojunction was mixed with water and sonicated at 120W for 30 min to obtain a Ti3C2 / TiO2 heterojunction suspension of 1 mg / mL. The palladium nanoparticles were mixed with water and sonicated at 120W for 30 min to obtain a palladium nanoparticle suspension of 1 mg / mL. 18 mL of the Ti3C2 / TiO2 heterojunction suspension of 1 mg / mL and 2 mL of the palladium nanoparticle suspension of 1 mg / mL (the mass ratio of Ti3C2 / TiO2 heterojunction to palladium nanoparticles was 9:1) were mixed and sonicated at 120W for 30 min to obtain an active material suspension. After filtration and drying, the hydrogen-sensitive material was obtained.

[0095] Example 2

[0096] (1) 1.6 g LiF was slowly dissolved in 40 mL of 6 mol / L HCl and stirred for 15 min to ensure complete dissolution. 1 g Ti3AlC2 (the mass ratio of Ti3AlC2 to lithium fluoride was 1:1.6) was slowly added and stirred at 35 °C for 48 hours. The etched solution was first washed twice with HCl (1 mol / L) to remove excess LiF, and then washed with deionized water and centrifuged at 3500 rpm for 5 min each time, for a total of 7 centrifugations to make the pH of the solution greater than 6. The precipitate was collected and finally placed in a vacuum drying oven and dried at 60 °C for 12 hours to obtain multilayer titanium carbide. The obtained multilayer titanium carbide was added to deionized water (the mass ratio of multilayer titanium carbide to water was 2 mg:1 mL) and ultrasonicated at 120 W for 1 h. The mixture was then centrifuged at 3500 rpm for 1 hour and titanium carbide nanosheets (400 mesh) were collected by filtration, drying and grinding.

[0097] (2) Add titanium carbide nanosheets into a tube furnace and anneal at 350°C for 1 h in a vacuum environment to obtain Ti3C2 / TiO2 heterojunction;

[0098] (3) Dissolve 17.7 mg of PdCl2 in 6 mol / L HCl to prepare 0.05 mol / L H2PdCl4. Dissolve 10 ml of ethylene glycol and 0.13 g of polyvinylpyrrolidone (PVP) in the H2PdCl4 solution. Add 0.1 mol / L NaOH solution to adjust the pH to 11. React at 80 °C for 2 hours. Wash the product twice with deionized water and ethanol. Dry at 40 °C for 12 hours to obtain palladium nanoparticles.

[0099] (4) The Ti3C2 / TiO2 heterojunction was mixed with water and sonicated at 120W for 30 min to obtain a Ti3C2 / TiO2 heterojunction suspension with a concentration of 1 mg / mL. The palladium nanoparticles were mixed with water and sonicated at 120W for 30 min to obtain a palladium nanoparticle suspension with a concentration of 1 mg / mL. 18 mL of the Ti3C2 / TiO2 heterojunction suspension with a concentration of 1 mg / mL and 2 mL of the palladium nanoparticle suspension with a concentration of 1 mg / mL (the mass ratio of Ti3C2 / TiO2 heterojunction to palladium nanoparticles was 9:1) were mixed and sonicated at 120W for 30 min to obtain an active material suspension.

[0100] (5) Take 50 μL of the active material suspension and drop it onto the interdigitated electrode (surface area 0.5 cm²). 2 After washing and drying, a hydrogen sensor is obtained.

[0101] Example 3

[0102] (1) 1.6 g LiF was slowly dissolved in 40 mL of 6 mol / L HCl and stirred for 15 min to ensure complete dissolution. 1 g Ti3AlC2 was slowly added and stirred at 35 °C for 48 hours. The etched solution was first washed twice with HCl (1 mol / L) to remove excess LiF, and then washed with deionized water and centrifuged at 3500 rpm for 5 min each time, for a total of 7 centrifugations to make the pH of the solution greater than 6. The precipitate was collected and finally placed in a vacuum drying oven and dried at 60 °C for 12 hours to obtain multilayer titanium carbide. The obtained multilayer titanium carbide was added to deionized water (the mass ratio of multilayer titanium carbide to water was 2 mg: 1 mL) and ultrasonicated at 120 W for 1 h. Next, the mixture was centrifuged at 3500 rpm for 1 hour and titanium carbide nanosheets (400 mesh) were collected by filtration, drying and grinding.

[0103] (2) Add titanium carbide nanosheets into a tube furnace and anneal at 350°C for 1 h in a vacuum environment to obtain Ti3C2 / TiO2 heterojunction;

[0104] (3) Dissolve 17.7 mg of PdCl2 in 6 mol / L HCl to prepare 0.05 mol / L H2PdCl4. Dissolve 10 ml of ethylene glycol and 0.13 g of polyvinylpyrrolidone (PVP) in the H2PdCl4 solution. Add 0.1 mol / L NaOH solution to adjust the pH to 11. React at 80 °C for 2 hours. Wash the product twice with deionized water and ethanol. Dry at 40 °C for 12 hours to obtain palladium nanoparticles.

[0105] (4) The Ti3C2 / TiO2 heterojunction was mixed with water and sonicated at 120W for 30 min to obtain a Ti3C2 / TiO2 heterojunction suspension with a concentration of 1 mg / mL. The palladium nanoparticles were mixed with water and sonicated at 120W for 30 min to obtain a palladium nanoparticle suspension with a concentration of 1 mg / mL. 18 mL of the Ti3C2 / TiO2 heterojunction suspension with a concentration of 1 mg / mL and 2 mL of the palladium nanoparticle suspension with a concentration of 1 mg / mL were mixed and sonicated at 120W for 30 min to obtain an active material suspension.

[0106] (5) Dissolve 216 mg Zn(AC)2·2H2O and 15 mL 2-methylimidazole in 30 mL methanol, stir at room temperature for 24 hours, filter, dry to obtain ZIF-8, and then mix ZIF-8 with 30 mL methanol to obtain ZIF-8 solution.

[0107] (6) Take 50 μL of the active material suspension and drop it onto the interdigitated electrode (surface area 0.5 cm²). 2 The sample was then immersed in ZIF-8 solution for 0.5 h, washed three times with ethanol, and dried under vacuum at 40 °C for 12 h to obtain the hydrogen sensor.

[0108] Example 4

[0109] Replace the annealing temperature in step (2) of Example 2 with 500℃, and keep all other parameters the same as in Example 2.

[0110] Example 5

[0111] Replace the annealing temperature in step (2) of Example 2 with 650°C, and keep all other parameters the same as in Example 2.

[0112] Example 6

[0113] Replace the annealing temperature in step (2) of Example 3 with 500℃, and keep all other parameters the same as in Example 3.

[0114] Example 7

[0115] Replace the annealing temperature in step (2) of Example 3 with 650°C, and keep all other parameters the same as in Example 3.

[0116] Example 8

[0117] Replace the soaking time in step (6) of Example 6 with 1 hour, and keep all other parameters the same as in Example 6.

[0118] Example 9

[0119] Replace the soaking time in step (6) of Example 6 with 3h, and keep all other parameters the same as in Example 6.

[0120] Example 10

[0121] Replace the soaking time in step (6) of Example 6 with 5h, and keep all other parameters the same as in Example 6.

[0122] The hydrogen sensor prepared in Example 4 was placed in pure argon gas and a mixture of hydrogen and argon gas with a volume concentration of 1%, respectively. The resistance changes of the active material were recorded and collected using an electrical measurement device under dark conditions, ultraviolet light irradiation, and infrared light irradiation. Under ultraviolet and infrared irradiation at room temperature, the sensitivity to 1% hydrogen gas reached 69.9%, with a response time of 16 s.

[0123] The hydrogen sensors prepared in Examples 4, 6, and 8-10 were placed in pure argon gas and in environments containing 1% volume concentration of hydrogen, CO, NH3, NO2, acetone, and toluene, respectively. The resistance changes of the active material were recorded and collected using an electrical measurement device under dark conditions, ultraviolet light irradiation, and infrared light irradiation. The results are listed in Table 1.

[0124] Table 1. Sensitivity of the hydrogen sensors prepared in Examples 4, 6, and 8-10 to different gases.

[0125] Example 4 Example 6 Example 8 Example 9 Example 10 <![CDATA[H2(1%)]]> 69.9 65.2 61.4 45.6 33.2 CO (1%) 43.2 11.7 4.2 1.1 0.27 <![CDATA[NH3(1%)]]> 17.5 8.8 2.6 0.92 0.52 <![CDATA[NO2(1%)]]> 14.5 4.6 1.2 0.45 0.36 Acetone (1%) 13.4 4.6 0.8 0.45 0.22 Toluene (1%) 10.45 3.2 0.5 0.23 0.18

[0126] As can be seen from Table 1, after being impregnated with ZIF-8 solution, the sensor prepared in this invention exhibits a sharp decrease in response to gases other than hydrogen, demonstrating excellent selectivity for hydrogen.

[0127] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A hydrogen sensitive material, comprising a Ti3C2 / TiO2 heterojunction and palladium nanoparticles supported on the surface of the Ti3C2 / TiO2 heterojunction; the palladium nanoparticles have a particle size of 4-6 nm. A method for preparing the hydrogen sensitive material, comprising the following steps: (1) annealing titanium carbide to obtain a Ti3C2 / TiO2 heterojunction; (2) mixing the Ti3C2 / TiO2 heterojunction obtained in step (1) with water to obtain a Ti3C2 / TiO2 heterojunction suspension; (3) mixing the Ti3C2 / TiO2 heterojunction suspension obtained in step (2) with a palladium nanoparticle suspension and then drying to obtain the hydrogen sensitive material. 2.The method for preparing the hydrogen sensitive material of claim 1, comprising the following steps: (1) annealing titanium carbide to obtain a Ti3C2 / TiO2 heterojunction; (2) mixing the Ti3C2 / TiO2 heterojunction obtained in step (1) with water to obtain a Ti3C2 / TiO2 heterojunction suspension; (3) mixing the Ti3C2 / TiO2 heterojunction suspension obtained in step (2) with a palladium nanoparticle suspension and then drying to obtain the hydrogen sensitive material.

3. The production method according to claim 2, characterized by, The annealing temperature in step (1) is 350-650℃.

4. The production method according to claim 2 or 3, characterized by, The annealing time in step (1) is 0.5-1.5 h.

5. The preparation method according to claim 2, characterized in that, The mass ratio of the Ti3C2 / TiO2 heterojunction in the Ti3C2 / TiO2 heterojunction suspension to the palladium nanoparticles in the palladium nanoparticle suspension in step (3) is (8-10) :

1.

6. A hydrogen-sensitive sensor, characterised in that It further comprises a ZIF-8 metal organic framework material layer deposited outside the active material layer.

7. The hydrogen-sensitive sensor of claim 6, wherein 8.The method for preparing the hydrogen sensitive sensor of claim 7, comprising the following steps: a. depositing an active material on the interdigital electrode to obtain an interdigital electrode with an active material layer deposited thereon; b. immersing the interdigital electrode with the active material layer deposited thereon obtained in step a in a ZIF-8 solution to obtain a hydrogen sensitive sensor. 9.The use of the hydrogen sensitive sensor of claim 6 or 7 or prepared according to the method of claim 8 in hydrogen detection. ​