Room temperature hydrogen sensitive material based on transition metal doping and preparation method thereof

Abstract

The invention provides a room-temperature hydrogen-sensitive material based on transition metal doping and a preparation method of the room-temperature hydrogen-sensitive material, and belongs to the technical field of semiconductor gas sensor materials. Aiming at the problems that an existing hydrogen sensor needs to work at a high temperature, the response speed is low, the preparation process is complex, and pollution is serious, the room-temperature hydrogen-sensitive material based on transition metal doping is prepared by combining hydrothermal synthesis with a hydrobromic acid-assisted ion exchange process. The response value of the material to 5000ppm hydrogen at room temperature reaches 65.4%, the response / recovery time is only 6 seconds / 36 seconds, meanwhile, an environment-friendly process is adopted to replace strongly corrosive acid, the cost is reduced by 80%, and the material is suitable for high-sensitivity and rapid leakage monitoring of hydrogen energy storage and transportation facilities.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor gas sensor materials, and in particular to a room-temperature hydrogen-sensitive material based on transition metal doping and a preparation method thereof. Background Art

[0002] Hydrogen sensors have important applications in hydrogen energy safety monitoring, but traditional technologies have significant drawbacks. For example, SnO2-based sensors require high temperatures above 200°C and rely on external heating modules, resulting in high energy consumption and potential safety hazards. Their response / recovery times typically exceed 60 seconds, making them difficult to meet real-time monitoring requirements.

[0003] The modification of existing niobium pentoxide (Nb2O5) based sensors mostly relies on the doping of precious metals (such as Pt, Pd), which is costly and requires the use of concentrated hydrochloric acid or nitric acid in the preparation process, resulting in serious acid mist pollution and residual Cl - It will also reduce the stability of the material. Related research shows that nanowire structures can be prepared by hydrochloric acid treatment, but Cl - It is difficult to completely remove, and strong acid operation is risky. Currently, there are no reports of Nb2O5-based hydrogen-sensitive materials using hydrobromic acid (HBr)-assisted ion exchange combined with nickel chloride thermal decomposition doping. There is also a lack of solutions for enhancing room-temperature hydrogen sensitivity through the synergistic effect of heterojunctions and interphases.

[0004] Therefore, there is an urgent need to develop a hydrogen-sensitive material that works at room temperature, responds quickly, is environmentally friendly, and low-cost. Summary of the Invention

[0005] The present invention provides a room-temperature hydrogen-sensitive material based on transition metal doping and a preparation method thereof, which are used to solve the defects of the prior art such as high temperature dependence, slow response speed, complex preparation process, pollution and high cost.

[0006] In one aspect, the present invention provides a method for preparing a room-temperature hydrogen-sensitive material based on transition metal doping, characterized in that it comprises the following steps: (1) Adding niobium powder, NaOH and deionized water into a hydrothermal reactor for hydrothermal reaction, washing to pH = 7 and then vacuum drying to obtain a sodium niobate precursor; (2) Immersing the precursor in a hydrobromic acid solution and stirring it, allowing it to react to obtain a niobate precipitate; (3) NiCl2·6H2O is added to the niobate precipitate and mixed and ground, followed by annealing to obtain a room-temperature hydrogen-sensitive material based on transition metal doping; In step (1), the mass ratio of the niobium powder, NaOH and deionized water is 1:(50-90):(150-240); In step (2), the concentration of the hydrobromic acid solution is 1.95~2.05M; In step (3), the mass ratio of NiCl2·6H2O to niobic acid precipitate is 1:2~5.

[0007] According to a method for preparing a room-temperature hydrogen-sensitive material based on transition metal doping provided by the present invention, in step (1), the temperature of the hydrothermal reaction is 110-150° C., and the time of the hydrothermal reaction is 12-48 hours.

[0008] According to a method for preparing a room-temperature hydrogen-sensitive material based on transition metal doping provided by the present invention, in step (2), the stirring treatment time is 7 to 11 hours, and the static reaction time is 6 to 10 hours.

[0009] According to a method for preparing a room-temperature hydrogen-sensitive material based on transition metal doping provided by the present invention, in step (3), the grinding time is 8 to 12 minutes.

[0010] According to a method for preparing a room-temperature hydrogen-sensitive material based on transition metal doping provided by the present invention, in step (3), the annealing treatment is carried out in an argon environment, the annealing treatment temperature is 700~1100°C, and the annealing treatment time is 2~6 hours.

[0011] On the other hand, the present invention also provides a room-temperature hydrogen-sensitive material based on transition metal doping, which is prepared by a preparation method of a room-temperature hydrogen-sensitive material based on transition metal doping.

[0012] According to the present invention, a room temperature hydrogen sensitive material based on transition metal doping is provided, wherein the room temperature hydrogen sensitive material based on transition metal doping is composed of a Ni-doped Nb2O5 matrix and forms a Nb2O5 / NiNb2O6 heterojunction and a (NiNb2O6) 0.6667 Intermediate phase and has a nanowire structure.

[0013] According to a room-temperature hydrogen-sensitive material based on transition metal doping provided by the present invention, the diameter of the nanowire structure is 50-80 nm, and the length of the nanowire structure is 5-12 μm.

[0014] On the other hand, the present invention also provides a hydrogen sensor comprising a room temperature hydrogen sensitive material doped with a transition metal as a sensitive film, wherein the thickness of the sensitive film formed on the surface of the hydrogen sensor is 4 to 6 μm.

[0015] On the other hand, the present invention also provides a method for preparing a hydrogen sensor, comprising the following steps: (1) dispersing a room temperature hydrogen-sensitive material doped with a transition metal in ethanol to obtain a dispersion; (2) Applying the dispersed liquid droplets to the surface of the interdigital electrode and drying it to obtain a hydrogen sensor; The interdigitated electrodes are Ti / Pt electrodes; The drying temperature is 70-110° C., and the drying time is 20-60 minutes.

[0016] The room-temperature hydrogen-sensitive material based on transition metal doping and the preparation method thereof provided by the present invention use hydrobromic acid (HBr) to replace highly corrosive acid, and the byproducts are environmentally friendly NaBr and H2O, thus avoiding acid mist pollution.

[0017] The room temperature hydrogen sensitive material based on transition metal doping and its preparation method provided by the present invention forms Nb2O5 / NiNb2O6 heterojunction and (NiNb2O6) by Ni doping 0.6667 The intermediate phase synergistically enhances the surface electron depletion effect, and the response value to 5000ppmH2 at room temperature reaches 65.4%.

[0018] The room-temperature hydrogen-sensitive material based on transition metal doping and its preparation method provided by the present invention form a nanowire structure, provide a high specific surface area and gas diffusion channels, and the response / recovery time is only 6 seconds / 36 seconds.

[0019] The room temperature hydrogen sensitive material based on transition metal doping and its preparation method provided by the present invention avoids the use of precious metals through NiCl2 thermal decomposition doping process, reduces the cost by 80%, and Cl - Complete removal ensures material stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0021] Figure 1 Schematic diagram of the structure of a hydrogen sensor provided by an embodiment of the present invention; Figure 2 This is a process flow chart for preparing a room-temperature hydrogen-sensitive material based on transition metal doping provided by an embodiment of the present invention; Figure 3 is an XRD pattern of a room-temperature hydrogen-sensitive material based on transition metal doping provided in an embodiment of the present invention; Figure 4 This is one of the SEM images of the nanowire structure in the room-temperature hydrogen-sensitive material based on transition metal doping provided by an embodiment of the present invention; Figure 5 This is the second SEM image of the nanowire structure in the room-temperature hydrogen-sensitive material based on transition metal doping provided by an embodiment of the present invention; Figure 6 is a response / recovery curve of the hydrogen sensor provided by an embodiment of the present invention; Reference numerals: 1. Ti / Pt interdigital electrode; 2. SiO2 substrate. DETAILED DESCRIPTION

[0022] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0023] The present invention provides a method for preparing a room-temperature hydrogen-sensitive material based on transition metal doping, comprising the following steps: (1) Adding niobium powder, NaOH and deionized water into a hydrothermal reactor for hydrothermal reaction, washing to pH = 7 and then vacuum drying to obtain a sodium niobate precursor; (2) Immersing the precursor in a hydrobromic acid solution and stirring it, allowing it to react to obtain a niobate precipitate; (3) NiCl2·6H2O is added to the niobate precipitate and mixed and ground, followed by annealing to obtain a room-temperature hydrogen-sensitive material based on transition metal doping; In step (1), the mass ratio of the niobium powder, NaOH and deionized water is 1:(50-90):(150-240), preferably 1:(60-80):(160-220), and more preferably 1:(65-75):(165-200); In step (2), the concentration of the hydrobromic acid solution is 1.95~2.05M; In step (3), the mass ratio of NiCl2·6H2O to niobic acid precipitate is 1:2-5, preferably 1:2.5-4, and more preferably 1:3-3.5.

[0024] In the present invention, in step (1), the temperature of the hydrothermal reaction is 110-150°C, preferably 120-140°C, and more preferably 125-135°C; the time of the hydrothermal reaction is 12-48 hours, preferably 18-36 hours, and more preferably 24-30 hours.

[0025] In the present invention, in step (2), the stirring treatment time is 7 to 11 hours, preferably 8 to 10 hours, and more preferably 8.5 to 9.5 hours; the standing reaction time is 6 to 10 hours, preferably 7 to 9 hours, and more preferably 7.5 to 8.5 hours.

[0026] In the present invention, in step (3), the grinding time is 8 to 12 minutes, preferably 9 to 11 minutes, and more preferably 9.5 to 10.5 minutes.

[0027] In the present invention, in step (3), the annealing treatment is carried out in an argon environment, the annealing treatment temperature is 700~1100°C, preferably 750~1000°C, and more preferably 800~900°C; the annealing treatment time is 2~6 hours, preferably 2.5~5 hours, and more preferably 3~4 hours.

[0028] The present invention also provides a room-temperature hydrogen-sensitive material based on transition metal doping, which is prepared by a preparation method of a room-temperature hydrogen-sensitive material based on transition metal doping.

[0029] In the present invention, the room temperature hydrogen sensitive material based on transition metal doping is composed of a Ni-doped Nb2O5 matrix, and forms a Nb2O5 / NiNb2O6 heterojunction and a (NiNb2O6) 0.6667 Intermediate phase and has a nanowire structure.

[0030] In the present invention, the diameter of the nanowire structure is 50-80 nm, preferably 55-75 nm, and more preferably 60-70 nm; the length of the nanowire structure is 5-12 μm, preferably 7-10 μm.

[0031] The present invention also provides a hydrogen sensor, which includes a room-temperature hydrogen-sensitive material doped with a transition metal as a sensitive film, and the thickness of the sensitive film formed on the surface of the hydrogen sensor is 4 to 6 μm.

[0032] The present invention also provides a method for preparing a hydrogen sensor, comprising the following steps: (1) dispersing a room temperature hydrogen-sensitive material doped with a transition metal in ethanol to obtain a dispersion; (2) Applying the dispersed liquid droplets to the surface of the interdigital electrode and drying it to obtain a hydrogen sensor; The interdigitated electrodes are Ti / Pt electrodes; The drying temperature is 70-110° C., preferably 80-100° C., more preferably 85-110° C.; the drying time is 20-60 minutes, preferably 25-50 minutes, more preferably 30-40 minutes.

[0033] The following combination Figures 1 to 6 The present invention describes a room temperature hydrogen sensitive material based on transition metal doping and a preparation method thereof.

[0034] Figure 1 Schematic diagram of the structure of a hydrogen sensor provided by an embodiment of the present invention.

[0035] like Figure 1 As shown, the sensor comprises Ti / Pt interdigital electrodes with a spacing of 100 μm and a sensitive film covering the surface; and a SiO2 substrate supporting the interdigital electrodes. This structure detects hydrogen concentration by changing the resistance of the interdigital electrodes, demonstrating high sensitivity and rapid response.

[0036] Figure 2 This is a process flow chart for preparing a room-temperature hydrogen-sensitive material based on transition metal doping provided in an embodiment of the present invention.

[0037] like Figure 2 As shown in FIG, the preparation process includes: mixing niobium powder, NaOH and deionized water in proportion, hydrothermally reacting at 110-150°C for 12-48 hours, washing and drying to obtain a precursor; immersing the precursor in a 1.95-2.05 MHBr solution and stirring for 7-11 hours, and then allowing it to stand to generate a niobate precipitate; mixing NiCl2·6H2O with the precipitate and grinding it, annealing at 700-1100°C for 2-6 hours under an argon atmosphere, and then precipitating the niobium oxide. - It is removed in the form of HCl to form a Ni-doped Nb2O5 / NiNb2O6 heterojunction; the material is dispersed and drop-coated on the surface of the interdigital electrode and dried to form a sensitive film.

[0038] Figure 3 This is an XRD diagram of a room-temperature hydrogen-sensitive material based on transition metal doping provided in an embodiment of the present invention.

[0039] like Figure 3 As shown, the spectrum clearly shows the characteristic peaks of Nb2O5 phase (JCPDS27-1003): 2θ=22.5°, 28.3°, 36.5°, etc.; NiNb2O6 phase (JCPDS34-0421): 2θ=24.8°, 33.1°, 49.7°, etc.; (NiNb2O6) 0.6667 Interphase: Non-standard peaks at 2θ = 25.6° and 37.2° indicate that nickel doping causes lattice distortion and the formation of high-density oxygen vacancies. The three-phase coexistence structure significantly enhances the surface electron depletion effect of the material through the synergistic effect of the heterojunction and the interphase.

[0040] Figure 4 and Figure 5 This is an SEM image of the nanowire structure in the room-temperature hydrogen-sensitive material based on transition metal doping provided by an embodiment of the present invention.

[0041] like Figure 4 As shown, the material presents a uniform nanowire structure with a diameter of 50~80nm and a length of 5~12μm; Figure 5 The nanowires were further shown to have smooth surfaces and to be cross-linked to form a porous network. The high surface area provides fast pathways for hydrogen adsorption and diffusion, which is the key factor for the short response time.

[0042] Figure 6 This is the response / recovery curve of the hydrogen sensor provided by the embodiment of the present invention.

[0043] like Figure 6 As shown in the figure, under 5000ppm H₂ conditions at 25°C, the resistance value during the response phase dropped to 34.6% of the initial value within 6 seconds, and during the recovery phase, the resistance value recovered to 90% of the initial value within 36 seconds. The rapid response and recovery performance is attributed to the efficient gas diffusion of the nanowire structure and the fast charge transfer across the Schottky barrier at the heterojunction interface.

[0044] Example 1 Mix 0.24g of niobium powder, 16.67g of NaOH, and 40mL of deionized water, then transfer to a hydrothermal reactor. The mixture is hydrothermally reacted at 130°C for 24 hours. After completion of the reaction, the mixture is washed with deionized water to a pH of 7 and dried under vacuum at 60°C for 12 hours to obtain a sodium niobate precursor.

[0045] The precursor was immersed in a 2M hydrobromic acid solution and magnetically stirred for 9 hours, followed by 8 hours of static reaction. The precipitate was collected by filtration, washed three times with deionized water, and dried at 60°C to obtain a niobate precipitate.

[0046] NiCl₂·6H₂O and niobic acid precipitate were mixed in a mass ratio of 1:3 and ground for 10 minutes until uniform. The mixture was then annealed at 800°C for 3 hours under an argon atmosphere at a heating rate of 5°C / min in a tube furnace. After annealing, the mixture was naturally cooled to obtain a room-temperature hydrogen-sensitive material based on transition metal doping.

[0047] After testing, it was found that the room-temperature hydrogen-sensitive material doped with transition metals formed a nanowire structure with a diameter of 60~70nm and a length of 8~10μm.

[0048] The room-temperature hydrogen-sensitive material based on transition metal doping was dispersed in ethanol, ultrasonically treated for 30 minutes, and drop-coated onto the surface of the Ti / Pt interdigital electrode with a spacing of 100 μm.

[0049] The film was dried at 80° C. for 30 minutes to form a sensitive film with a thickness of 5 μm, thereby obtaining a hydrogen sensor.

[0050] The hydrogen sensor provided in this embodiment was tested in an environment of 25°C, 50% relative humidity, and 5000 ppm H2. The response value was 65.4%, the response time was 6 seconds, the recovery time was 36 seconds, the detection limit was 300 ppm, the humidity interference was ±35%, and the response value decayed by less than 5% after 30 days of continuous operation.

[0051] Example 2 Mix 0.24g of niobium powder, 18g of NaOH, and 45mL of deionized water, then transfer to a hydrothermal reactor. The mixture is hydrothermally reacted at 120°C for 36 hours. After completion of the reaction, the mixture is washed with deionized water to a pH of 7 and dried under vacuum at 60°C for 12 hours to obtain a sodium niobate precursor.

[0052] The precursor was immersed in a 1.98M hydrobromic acid solution and magnetically stirred for 8 hours, followed by a 7-hour stand. The precipitate was collected by filtration, washed three times with deionized water, and dried at 60°C to obtain a niobate precipitate.

[0053] NiCl₂·6H₂O and niobic acid precipitate were mixed in a mass ratio of 1:4 and ground for 12 minutes until homogeneous. The mixture was then annealed at 750°C for 4 hours under an argon atmosphere at a heating rate of 3°C / min in a tube furnace. After annealing, the mixture was naturally cooled to obtain a room-temperature hydrogen-sensitive material based on transition metal doping.

[0054] After testing, it was found that the room-temperature hydrogen-sensitive material doped with transition metals formed a nanowire structure with a diameter of 55~65nm and a length of 6~9μm.

[0055] The room-temperature hydrogen-sensitive material based on transition metal doping was dispersed in ethanol, ultrasonically treated for 30 minutes, and drop-coated onto the surface of the Ti / Pt interdigital electrode with a spacing of 100 μm.

[0056] The film was dried at 90° C. for 40 minutes to form a sensitive film with a thickness of 4.5 μm, thereby obtaining a hydrogen sensor.

[0057] The hydrogen sensor provided in this embodiment was tested in an environment of 25°C, 50% relative humidity, and 5000 ppm H2. The response value was 63.8%, the response time was 7 seconds, the recovery time was 38 seconds, the detection limit was 320 ppm, the humidity interference was ±38%, and the response value decayed by less than 6% after 30 days of continuous operation.

[0058] Example 3 Mix 0.24g of niobium powder, 14g of NaOH, and 35mL of deionized water, then transfer to a hydrothermal reactor. The mixture is hydrothermally reacted at 140°C for 18 hours. After the reaction, the mixture is washed with deionized water to a pH of 7 and dried under vacuum at 60°C for 12 hours to obtain a sodium niobate precursor.

[0059] The precursor was immersed in a 2.02M hydrobromic acid solution and magnetically stirred for 10 hours, followed by a 9-hour stand. The precipitate was collected by filtration, washed three times with deionized water, and dried at 60°C to obtain a niobate precipitate.

[0060] NiCl₂·6H₂O and niobic acid precipitate were mixed in a mass ratio of 1:2.5 and ground for 9 minutes until homogeneous. The mixture was then annealed at 850°C for 2.5 hours under an argon atmosphere in a tube furnace at a heating rate of 8°C / min. After annealing, the mixture was naturally cooled to obtain a room-temperature hydrogen-sensitive material based on transition metal doping.

[0061] After testing, it was found that the room-temperature hydrogen-sensitive material doped with transition metals formed a nanowire structure with a diameter of 70~80nm and a length of 10~12μm.

[0062] The room-temperature hydrogen-sensitive material based on transition metal doping was dispersed in ethanol, ultrasonically treated for 30 minutes, and drop-coated onto the surface of the Ti / Pt interdigital electrode with a spacing of 100 μm.

[0063] The film was dried at 100° C. for 25 minutes to form a sensitive film with a thickness of 6 μm, thereby obtaining a hydrogen sensor.

[0064] The hydrogen sensor provided in this embodiment was tested in an environment of 25°C, 50% relative humidity, and 5000 ppm H2. The response value was 67.1%, the response time was 5 seconds, the recovery time was 34 seconds, the detection limit was 280 ppm, the humidity interference was ±32%, and the response value decayed by less than 4% after 30 days of continuous operation.

[0065] Example 4 Mix 0.24g of niobium powder, 20g of NaOH, and 50mL of deionized water, then transfer to a hydrothermal reactor. The mixture is hydrothermally reacted at 115°C for 48 hours. After completion of the reaction, the mixture is washed with deionized water to a pH of 7 and dried under vacuum at 60°C for 12 hours to obtain a sodium niobate precursor.

[0066] The precursor was immersed in a 1.95M hydrobromic acid solution and magnetically stirred for 7 hours, followed by a 10-hour stand. The precipitate was collected by filtration, washed three times with deionized water, and dried at 60°C to obtain a niobate precipitate.

[0067] NiCl₂·6H₂O and niobic acid precipitate were mixed in a mass ratio of 1:5 and ground for 8 minutes until uniform. The mixture was then annealed at 900°C for 5 hours under an argon atmosphere at a heating rate of 4°C / min in a tube furnace. After annealing, the mixture was naturally cooled to obtain a room-temperature hydrogen-sensitive material based on transition metal doping.

[0068] After testing, it was found that the room-temperature hydrogen-sensitive material doped with transition metals formed a nanowire structure with a diameter of 50~60nm and a length of 5~7μm.

[0069] The room-temperature hydrogen-sensitive material based on transition metal doping was dispersed in ethanol, ultrasonically treated for 30 minutes, and drop-coated onto the surface of the Ti / Pt interdigital electrode with a spacing of 100 μm.

[0070] The film was dried at 70° C. for 60 minutes to form a sensitive film with a thickness of 4 μm, thereby obtaining a hydrogen sensor.

[0071] The hydrogen sensor provided in this embodiment was tested in an environment of 25°C, 50% relative humidity, and 5000 ppm H2. The response value was 60.2%, the response time was 8 seconds, the recovery time was 40 seconds, the detection limit was 350 ppm, the humidity interference was ±42%, and the response value decayed by less than 8% after 30 days of continuous operation.

[0072] Example 5 Mix 0.24g of niobium powder, 15g of NaOH, and 38mL of deionized water, then transfer to a hydrothermal reactor. Hydrothermally react at 150°C for 12 hours. After the reaction, wash with deionized water to a pH of 7 and dry in a vacuum at 60°C for 12 hours to obtain a sodium niobate precursor.

[0073] The precursor was immersed in a 2.05M hydrobromic acid solution and magnetically stirred for 11 hours, followed by a 6-hour stand. The precipitate was collected by filtration, washed three times with deionized water, and dried at 60°C to obtain a niobate precipitate.

[0074] NiCl₂·6H₂O and niobic acid precipitate were mixed in a mass ratio of 1:3.5 and ground for 11 minutes until uniform. The mixture was then annealed at 700°C for 6 hours under an argon atmosphere in a tube furnace at a heating rate of 2°C / min. After annealing, the mixture was naturally cooled to obtain a room-temperature hydrogen-sensitive material based on transition metal doping.

[0075] After testing, it was found that the room-temperature hydrogen-sensitive material doped with transition metals formed a nanowire structure with a diameter of 75~80nm and a length of 11~12μm.

[0076] The room-temperature hydrogen-sensitive material based on transition metal doping was dispersed in ethanol, ultrasonically treated for 30 minutes, and drop-coated onto the surface of the Ti / Pt interdigital electrode with a spacing of 100 μm.

[0077] The film was dried at 110° C. for 20 minutes to form a sensitive film with a thickness of 4 μm, thereby obtaining a hydrogen sensor.

[0078] The hydrogen sensor provided in this embodiment was tested in an environment of 25°C, 50% relative humidity, and 5000 ppm H2. The response value was 62.5%, the response time was 6.5 seconds, the recovery time was 37 seconds, the detection limit was 310 ppm, the humidity interference was ±37%, and the response value decayed by less than 5% after 30 days of continuous operation.

[0079] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for preparing a room temperature hydrogen-sensitive material based on transition metal doping, characterized in that: The following steps are involved: (1) Adding niobium powder, NaOH and deionized water into a hydrothermal reactor for hydrothermal reaction, washing to pH = 7 and then vacuum drying to obtain a sodium niobate precursor; (2) Immersing the precursor in a hydrobromic acid solution and stirring it, allowing it to react to obtain a niobate precipitate; (3) NiCl2·6H2O is added to the niobate precipitate and mixed and ground, followed by annealing to obtain a room-temperature hydrogen-sensitive material based on transition metal doping; In step (1), the mass ratio of the niobium powder, NaOH and deionized water is 1:(50-90):(150-240); In step (2), the concentration of the hydrobromic acid solution is 1.95~2.05M; In step (3), the mass ratio of NiCl2·6H2O to niobic acid precipitate is 1:2~5.

2. The method for preparing a room temperature hydrogen sensitive material based on transition metal doping according to claim 1, characterized in that: In step (1), the temperature of the hydrothermal reaction is 110-150° C., and the time of the hydrothermal reaction is 12-48 hours.

3. The method for preparing a room temperature hydrogen sensitive material based on transition metal doping according to claim 1, characterized in that: In step (2), the stirring treatment time is 7 to 11 hours, and the static reaction time is 6 to 10 hours.

4. The method for preparing a room temperature hydrogen sensitive material based on transition metal doping according to claim 1, characterized in that: In step (3), the grinding time is 8 to 12 minutes.

5. The method for preparing a room temperature hydrogen sensitive material based on transition metal doping according to claim 1, characterized in that: In step (3), the annealing treatment is performed in an argon environment, the annealing temperature is 700-1100° C., and the annealing time is 2-6 hours.

6. A room temperature hydrogen-sensitive material based on transition metal doping, characterized in that: It is prepared by the preparation method according to any one of claims 1 to 5.

7. The room-temperature hydrogen-sensitive material based on transition metal doping according to claim 6, characterized in that: The room temperature hydrogen sensitive material based on transition metal doping is composed of a Ni-doped Nb2O5 matrix and forms a Nb2O5 / NiNb2O6 heterojunction and a (NiNb2O6) 0.6667 Intermediate phase and has a nanowire structure.

8. The room-temperature hydrogen-sensitive material based on transition metal doping according to claim 7, characterized in that: The diameter of the nanowire structure is 50-80 nm, and the length of the nanowire structure is 5-12 μm.

9. A hydrogen sensor, characterized in that: The room-temperature hydrogen-sensitive material based on transition metal doping according to claim 6 is used as a sensitive film, and the thickness of the sensitive film formed on the surface of the hydrogen sensor is 4 to 6 μm.

10. The method for preparing a hydrogen sensor according to claim 9, wherein: The following steps are involved: (1) dispersing a room temperature hydrogen-sensitive material doped with a transition metal in ethanol to obtain a dispersion; (2) Applying the dispersed liquid droplets to the surface of the interdigital electrode and drying it to obtain a hydrogen sensor; The interdigitated electrodes are Ti / Pt electrodes; The drying temperature is 70-110° C., and the drying time is 20-60 minutes.

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