A high concentration hydrogen sensor and its preparation method and use

Abstract

The present invention belongs to the technical field of hydrogen sensors, and in particular, is a sensor suitable for testing hydrogen gas concentrations above 1%. The present invention is aimed at the difficulty of semiconductor-based gas sensors in sensing high-energy concentration hydrogen. Considering that precious metals such as palladium, gold, and platinum have selective adsorption of hydrogen and catalytic overflow effects on hydrogen, the activation energy of the reaction is reduced, and the synergistic effect of precious metals and semiconductors is used to increase the upper limit of hydrogen detection. A porous tin oxide or indium oxide porous film doped with precious metals is prepared as a semiconductor sensor device for detecting high-concentration hydrogen. The semiconductor high-concentration hydrogen sensor can detect hydrogen gas with a concentration of more than 1%, and has good reusability.

Description

Technical Field

[0001] The invention relates to the technical field of hydrogen sensors, in particular to a hydrogen sensor suitable for testing hydrogen with a concentration higher than 1%. Background Art

[0002] Hydrogen is expected to become a green and renewable energy source for a variety of applications in the coming years, including fuel cell vehicles, spacecraft, automobiles, generators and aircraft. However, this light and odorless gas is highly flammable, with a wide range of explosive concentrations, fast diffusion, low ignition energy and fast flame propagation speed. Therefore, hydrogen leakage during transportation, storage and use may lead to catastrophic consequences, and sensitive hydrogen gas sensors are necessary to monitor hydrogen leakage. There are many types of hydrogen gas sensors. According to the different principles of gas analysis methods, the mainstream hydrogen gas sensors on the market can be mainly divided into three categories: electrochemical, catalytic combustion and semiconductor. The electrochemical type is based on ionic conduction and is composed of membrane electrodes and electrolyte encapsulation. The gas concentration signal decomposes the electrolyte into positive and negative charged ions and transmits the signal through the electrode. Although it has the advantages of fast response speed, good stability and quantitative detection, the electrolyte life is short and temperature compensation is also difficult. The catalytic combustion type is that the sensitive material is in a conductive state. When the combustible gas (H 2 , CO, CH 4 When the heat generated by the contact combustion sensor (such as the presence of sulfides in the environment) comes into contact with oxygen in the air, a reaction will occur. The heat generated will cause the temperature of the thermal wire to rise, causing the resistance value to change. This contact combustion sensor has good stability and linearity, and can be used to detect the limits of flammable and explosive gases. However, this sensor is easily poisoned (the presence of sulfides in the environment) and has a large long-term drift. The semiconductor type is a sensor made using the property that semiconductor properties are easily affected by external conditions. It mainly uses semiconductor gas-sensitive materials. The redox reaction of the gas on the surface of the semiconductor sensitive material causes the internal carriers of the sensitive material to change and produce changes in macroscopic physical quantities. The gas concentration is obtained by testing the changes in these physical properties. Since the advent of semiconductor metal oxide gas sensors, they have been widely used due to a series of advantages such as high sensitivity, fast response, small size, light weight, easy integration, and compatibility with Si-based semiconductor processes. At present, it has become one of the world's largest and most widely used sensors.

[0003] Semiconductor metal oxide gas sensors can be used for H 2 Combustible gas explosion alarm, CO, H 2S and other toxic gases. General semiconductor sensors can detect hydrogen gas concentration range <1% (here we define <1% hydrogen as low concentration hydrogen, and above 1% as high concentration hydrogen). Too high gas concentration will cause the sensor response to reach saturation, making it impossible to distinguish the gas concentration and may even cause the sensor to be poisoned and lose its sensing ability. During the storage, transportation and use of hydrogen, once the gas leaks, it is very likely to exceed 1%, so the development of high-concentration hydrogen sensors is extremely challenging. Summary of the invention

[0004] One of the purposes of the present invention is to provide a method for preparing a high-concentration hydrogen sensor. The hydrogen sensor prepared by the method can test high-concentration hydrogen with a concentration of more than 1%.

[0005] To achieve the above object, the present invention adopts the following technical solution: A method for preparing a semiconductor high-concentration hydrogen sensor, comprising the following steps:

[0006] S1, forming an orderly arranged, single-layer organic colloidal sphere array layer on a hydrophilic flat substrate;

[0007] S2, using water as solvent, mixing tin tetrachloride or indium nitrate with aluminum nitrate, palladium chloride, chloroauric acid, and chloroplatinic acid to obtain a precursor solution, immersing the flat substrate with the organic colloidal sphere array layer attached into the precursor solution, and the organic colloidal sphere array layer floats in the precursor solution after falling off from the flat substrate, and the gaps between the organic colloidal spheres are filled with the precursor solution;

[0008] S3, transferring the organic colloidal sphere array layer in the precursor solution to the surface of the hydrophilic-treated ceramic tube device;

[0009] S4, placing the ceramic tube device covered with the organic colloidal sphere array layer at 60-120° C. for drying for 10-30 min, until the solvent in the precursor solution in the gaps of the organic colloidal spheres evaporates, and precipitates are generated in the gaps between adjacent organic colloidal spheres and between the organic colloidal spheres and the ceramic tube;

[0010] S5. Then, the colloid balls are removed by annealing at 400-600° C. for 1-2 hours, and an ordered porous film is formed on the ceramic tube sensor substrate, thereby obtaining a semiconductor high-concentration hydrogen sensor.

[0011] As a further improvement of the preparation method of semiconductor high concentration hydrogen sensor:

[0012] Preferably, the concentration of tin tetrachloride or indium nitrate in the precursor solution is 0.1-0.3 mol / L, the concentration of aluminum nitrate is 0.01-0.03 mol / L, and the concentrations of palladium chloride, chloroauric acid and chloroplatinic acid are the same and are 0.001-0.01 mol / L.

[0013] Preferably, the preparation method of the organic colloidal sphere array layer is as follows: the method for forming an organic colloidal sphere array layer on a hydrophilic flat substrate is as follows: the flat substrate is treated to be hydrophilic, and an organic colloidal sphere aqueous solution with a diameter of 150-500nm and a mass content of 10wt% is mixed with ethanol in a volume ratio of 1:1 to obtain an organic colloidal sphere mixed solution; the mixed solution is slowly dripped from the edge of the hydrophilic treated flat substrate onto the flat substrate, and the organic colloidal spheres self-assemble on the air-water interface to form a single-layer organic colloidal sphere array, which is naturally dried.

[0014] Preferably, the specific steps of hydrophilic treatment of the flat substrate are as follows: 1) ultrasonically cleaning the flat substrate in ethanol and then cleaning with deionized water; 2) ultrasonically cleaning it in deionized water and drying it; 3) placing the dried flat substrate in a plasma cleaning machine to obtain a clean, hydrophilic surface.

[0015] Preferably, the ceramic tube device in step S3 is cleaned in a plasma cleaner before use to obtain a clean and hydrophilic surface.

[0016] Preferably, the flat substrate is made of a glass slide, a silicon wafer or a ceramic wafer.

[0017] Preferably, the organic colloidal spheres are made of polystyrene or polymethyl methacrylate.

[0018] A second object of the present invention is to provide a semiconductor high-concentration hydrogen sensor manufactured by the above-mentioned preparation method.

[0019] A third object of the present invention is to provide a use of the above-mentioned semiconductor high-concentration hydrogen sensor in detecting hydrogen, wherein the volume concentration of hydrogen is above 1%.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1) In view of the current difficulties in sensing high-energy concentration hydrogen based on semiconductor-based gas sensors, and considering that precious metals such as palladium, gold, and platinum have selective adsorption of hydrogen and catalytic overflow effects on hydrogen, reducing the activation energy of the reaction, the present invention utilizes the synergistic effect of precious metals and semiconductors to increase the upper limit of hydrogen detection, and obtains a porous tin oxide or indium oxide film doped with precious metals, which can be used as a semiconductor sensor device for detecting high-concentration hydrogen. This application uses tin oxide or indium oxide as the main material of the semiconductor ordered sensitive porous film device, and aluminum oxide as a stabilizer for the film structure. The semiconductor film is co-doped with precious metals such as palladium, platinum, and gold to prevent it from being poisoned and failing under high-concentration hydrogen.

[0022] 2) Compared with traditional devices based on particle films, the precious metal-doped tin dioxide porous film structure prepared with the assistance of colloidal sphere templates can select appropriate templates to control the size of the pores. And this porous film has a large specific surface area compared to traditional granular materials, so that the gas can respond quickly after contact with the surface. Compared with traditional films, devices based on this ordered porous film have good controllability and repeatability, because as long as the size of the colloidal sphere template is controlled, the device and device or the film structure can be highly consistent. The most important thing is that traditional semiconductor hydrogen sensor devices can detect hydrogen volume concentrations not exceeding 4%, while our multi-precious metal-doped tin dioxide porous film can detect hydrogen volume concentrations up to 10%.

[0023] 3) The present invention provides a method for preparing a semiconductor high-concentration hydrogen sensor:

[0024] When preparing the organic colloidal sphere array layer, due to the energy minimization principle, the polystyrene sphere ethanol mixture self-assembles on the air-water interface of the hydrophilic treated flat substrate and forms a densely packed monolayer film;

[0025] When the organic colloidal sphere array layer is immersed in a precursor solution, the single-layer colloidal crystal can gradually detach from the substrate and float on the surface of the solution due to the difference in wettability and the surface tension of the solution.

[0026] The organic colloidal sphere array film is transferred to the surface of a hydrophilic ceramic tube device, and the gaps between the colloidal spheres are filled with solution due to capillary action.

[0027] After drying, the water in the precursor solution evaporates, and a composite solid film composed of five compounds, tin tetrachloride, aluminum nitrate, palladium chloride, chloroauric acid and chloroplatinic acid, is obtained in the gaps between the colloidal balls and between the colloidal balls and the ceramic tube.

[0028] After high temperature annealing treatment, the composite solid film is transformed into a composite film of tin oxide or indium oxide and aluminum oxide, palladium, gold, and platinum after a high temperature reaction, and the organic colloid spheres are transformed into carbon dioxide gas after a high temperature reaction with oxygen, and finally an oxide / precious metal composite film with a honeycomb ordered porous structure is obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The morphology analysis of the hydrogen sensor device prepared in Example 1 of the present invention is performed, wherein (a) is a picture of a ceramic tube device welded to a commercial hexagonal base; (b) and (c) are microscopic morphology pictures of the ceramic tube device obtained under a scanning electron microscope; and (d) is a locally enlarged scanning electron microscope picture of a porous film.

[0030] Figure 2This is a performance test of the hydrogen sensor device prepared in Example 1, wherein (a) is the response time and recovery time of the hydrogen sensor device to 1% hydrogen; (b) is the response of the hydrogen sensor device to different concentrations of hydrogen in the range of 0.5%-10%; and (c) is the repeatability test of the hydrogen sensor device.

[0031] Figure 3 The hydrogen sensor device prepared in Example 2 has a sensitivity and repeatability in response to hydrogen of different concentrations.

[0032] Figure 4 The hydrogen sensor device prepared in Example 3 has a sensitivity and repeatability in response to hydrogen of different concentrations. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present invention.

[0034] Example 1

[0035] This embodiment provides a method for preparing a high concentration hydrogen sensor, which specifically includes the following steps:

[0036] S1. Purchase an organic colloidal sphere aqueous solution with a mass content of 10wt%, where the organic colloidal sphere is a polystyrene sphere (PS, with a diameter of 150-500nm), and mix the organic colloidal sphere aqueous solution with ethanol at a volume ratio of 1:1 to form a PS sphere mixed solution. The prepared PS sphere mixed solution is slowly dripped from the edge onto a hydrophilic treated flat substrate covered with a deionized water film. The PS spheres self-assemble at the air-water interface and form a densely packed monolayer film. After removing the moisture with filter paper and drying naturally, a monolayer of ordered PS colloidal sphere array layers is formed on the flat substrate;

[0037] S2, using water as solvent, adding tin tetrachloride and aluminum nitrate, palladium chloride, chloroauric acid and chloroplatinic acid to obtain a precursor solution, wherein the concentration of tin tetrachloride is 0.2 mol / L, the concentration of aluminum nitrate is 0.01 mol / L, the concentration of palladium chloride, chloroauric acid and chloroplatinic acid are all 0.001 mol / L, immersing the hydrophilic flat substrate with the PS colloidal sphere array layer attached into the precursor solution, the PS colloidal sphere array layer falls off the flat substrate and floats in the precursor solution, and the gaps between the PS colloidal spheres are filled with the precursor solution;

[0038] S3, then the floating single-layer PS colloidal sphere template is picked up with a hydrophilic ceramic tube device and covered on the surface of the ceramic tube device, and the gaps between the colloidal spheres are filled with solution due to capillary action;

[0039] S4, placing the ceramic tube device covered with the PS colloidal sphere array layer at 120° C. for 30 min of drying treatment, until the solvent in the precursor solution in the gaps of the PS colloidal spheres evaporates, and precipitates are generated in the gaps between adjacent PS colloidal spheres and between the PS colloidal spheres and the ceramic tube;

[0040] S5, then anneal at 400℃ for 2h to burn out the PS colloid spheres, and finally form SnO on the ceramic tube sensor substrate. 2 Micro / nano ordered porous films constitute high-concentration hydrogen sensor devices.

[0041] The ordered porous high-concentration hydrogen sensor device prepared according to the above preparation method is analyzed for morphology. It is evenly distributed in a single layer on the ceramic tube and presents a honeycomb structure, such as Figure 1 (a)-(d) are shown. (a) is a picture of a ceramic tube device welded to a commercial hexagonal base; (b) and (c) are microscopic morphology pictures of the ceramic tube device obtained under a scanning electron microscope; (d) is a local magnified scanning electron microscope picture of a porous film. Figure 1 It can be seen that although the ceramic tube substrate has a rough curved surface structure, the composite film prepared thereon still has a continuous, complete and ordered porous structure, which can ensure the repeatability and stability of the signal.

[0042] The response time and recovery time of the prepared high concentration hydrogen sensor device to 1% volume concentration of hydrogen were tested. Figure 2 (a). When testing 1% hydrogen, the device's response time is 1.3s and the recovery time is 7.2s. Further, we tested the device's response characteristics to different concentrations of hydrogen, such as Figure 2 As shown in (b), the device has a good step response to hydrogen in the range of 0.1%-10% volume concentration. In addition, we tested the repeatability of the device, and the five cycle tests had similar results, such as Figure 2 (c) is shown. Figure 2 It can be seen that the SnO prepared in this embodiment 2 The micro / nano ordered porous film exhibits a rapid and sensitive response to hydrogen and has an extremely wide concentration response range. The upper limit of the volume concentration can reach 10%, and it also has good signal reproducibility.

[0043] Example 2

[0044] This embodiment provides a method for preparing a high-concentration hydrogen sensor, with specific reference to Example 1, except that the precursor solution in step S2 does not contain tin tetrachloride, but 0.3 mol / L indium nitrate is added to form an InO ordered porous film on the ceramic tube sensor substrate to constitute a high-concentration hydrogen sensor device.

[0045] The prepared hydrogen sensor device was tested for its sensitivity and repeatability to different concentrations of hydrogen. The results are as follows: Figure 3 Similarly, the high-concentration hydrogen sensor device prepared in this embodiment exhibits strong response characteristics to hydrogen with a volume concentration of 0.1%-10%, and has good signal reproducibility.

[0046] Example 3

[0047] This embodiment provides a method for preparing a high-concentration hydrogen sensor, which is specifically referred to in Example 1, except that the concentration of tin tetrachloride in the precursor solution in step S2 is 0.3 mol / L, and a high-concentration hydrogen sensor device is finally prepared.

[0048] The prepared hydrogen sensor device was tested for its sensitivity and repeatability to different concentrations of hydrogen. The results are as follows: Figure 4 Similarly, the high-concentration hydrogen sensor device prepared in this embodiment exhibits strong response characteristics to hydrogen with a volume concentration of 0.1%-10%, and has good signal reproducibility.

[0049] Those skilled in the art should understand that the above are only some specific embodiments of the present invention, rather than all embodiments. It should be noted that for those of ordinary skill in the art, many modifications and improvements can be made, and all modifications or improvements that do not exceed the scope of protection of the present invention should be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a semiconductor high-concentration hydrogen sensor, characterized in that: The steps include: S1, forming an orderly arranged, single-layer organic colloidal sphere array layer on a hydrophilic flat substrate; S2, using water as solvent, mixing tin tetrachloride or indium nitrate with aluminum nitrate, palladium chloride, chloroauric acid, and chloroplatinic acid to obtain a precursor solution, immersing a hydrophilic flat substrate with an organic colloidal sphere array layer attached thereto into the precursor solution, and the organic colloidal sphere array layer floats in the precursor solution after falling off from the flat substrate, and the gaps between the organic colloidal spheres are filled with the precursor solution; S3, transferring the organic colloidal sphere array layer in the precursor solution to the surface of the hydrophilic-treated ceramic tube device; S4, placing the ceramic tube device covered with the organic colloidal sphere array layer at 60-120° C. for drying for 10-30 min, until the solvent in the precursor solution in the gaps of the organic colloidal spheres evaporates, and precipitates are generated in the gaps between adjacent organic colloidal spheres and between the organic colloidal spheres and the ceramic tube device; S5. Then, the device is annealed at 400-600° C. for 1-2 hours to remove the colloidal spheres, and an ordered porous film is formed on the ceramic tube device, thereby obtaining a semiconductor high-concentration hydrogen sensor.

2. The method for preparing a semiconductor high-concentration hydrogen sensor according to claim 1, characterized in that: The concentration of tin tetrachloride or indium nitrate in the precursor solution is 0.1-0.3 mol / L, the concentration of aluminum nitrate is 0.01-0.03 mol / L, and the concentrations of palladium chloride, chloroauric acid and chloroplatinic acid are the same and are 0.001-0.01 mol / L.

3. The method for preparing a semiconductor high-concentration hydrogen sensor according to claim 1, characterized in that: The method for forming an organic colloidal sphere array layer on a hydrophilic flat substrate is as follows: the flat substrate is treated to be hydrophilic, and an organic colloidal sphere aqueous solution with a diameter of 150-500nm and a mass content of 10wt% is mixed with ethanol in a volume ratio of 1:1 to obtain an organic colloidal sphere mixed solution; the mixed solution is slowly dripped from the edge of the hydrophilic treated flat substrate onto the flat substrate, and the organic colloidal spheres are self-assembled on the air-water interface to form a single-layer organic colloidal sphere array, which is naturally dried.

4. The method for preparing a semiconductor high-concentration hydrogen sensor according to claim 3, characterized in that: The specific steps of treating the flat substrate for hydrophilicity are as follows: 1) ultrasonically cleaning the flat substrate in ethanol and then cleaning it with deionized water; 2) ultrasonically cleaning it in deionized water and drying it; 3) placing the dried flat substrate in a plasma cleaning machine to obtain a clean, hydrophilic surface.

5. The method for preparing a semiconductor high-concentration hydrogen sensor according to claim 1, characterized in that: The ceramic tube device in step S3 is placed in a plasma cleaning machine for cleaning before use to obtain a clean and hydrophilic surface.

6. The method for preparing a semiconductor high-concentration hydrogen sensor according to claim 1 or 3, characterized in that: The material of the flat substrate is a glass slide, a silicon wafer or a ceramic wafer.

7. The method for preparing a semiconductor high-concentration hydrogen sensor according to claim 1 or 3, characterized in that: The organic colloid spheres are made of polystyrene or polymethyl methacrylate.

8. A semiconductor high-concentration hydrogen sensor made by the preparation method according to any one of claims 1 to 7.

9. Use of the semiconductor high-concentration hydrogen sensor according to claim 8 for detecting hydrogen, characterized in that: The volume concentration of hydrogen gas is 1% or more.

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