A method for preparing a calorimetric hydrogen sensor operating at room temperature

Abstract

The application relates to a preparation method of a room-temperature-operated calorimetric hydrogen sensor, comprising the following steps: S1. providing a MEMS monocrystalline silicon thermoelectric chip; S2. preparing a two-dimensional palladium metalene material; S3. dispersing the two-dimensional palladium metalene material in a solvent to prepare a sensitive material dispersion liquid, and then performing ultrasonic treatment to form a uniformly dispersed and stable suspension system; S4. using a microspotting instrument to accurately spot the sensitive material dispersion liquid on a sensitive area of a hot end of the MEMS monocrystalline silicon thermoelectric chip; S5. after the spotting is completed, drying is performed in an oven; and S6. after the drying, aging treatment is performed, so that the calorimetric hydrogen sensor is prepared. In the application, the two-dimensional palladium metalene has a high-efficiency catalysis and signal amplification effect on hydrogen at room temperature, so that the sensor can maintain rapid response and high sensitivity while greatly reducing device energy consumption, thereby realizing a room-temperature hydrogen detection technical scheme which takes into account performance and energy efficiency.

Description

Technical Field

[0001] This invention belongs to the field of calorimetric sensors, and specifically relates to a method for preparing a calorimetric hydrogen sensor that operates at room temperature. Background Technology

[0002] Hydrogen energy, as a highly efficient and clean energy source, is widely regarded as a key component of the future energy system transformation due to its significant advantages, such as combustion products consisting only of water and high energy density. However, hydrogen itself possesses flammable and explosive properties (an explosive limit range of 4%–75%), extremely low ignition energy (only 0.02 mJ), and is colorless and odorless, making it difficult to detect directly through human senses. These inherent dangers pose severe safety challenges to its practical application. Throughout the entire hydrogen production, storage, transportation, and use chain, even a minor leak can trigger a fire or even an explosion. Therefore, developing reliable, sensitive, and rapid-response hydrogen leak monitoring technology has become a prerequisite and one of the core issues for promoting the safe and large-scale development of the hydrogen energy industry.

[0003] Among numerous hydrogen sensing technologies, calorimetric sensors based on the principle of catalytic combustion have long held a dominant position in industrial safety monitoring due to their comprehensive advantages, including stable response, wide measurement range (covering from the lower explosive limit to high concentrations), strong anti-interference ability, and high long-term reliability. However, these traditional sensors must rely on continuous high-temperature operation to maintain sufficient catalytic activity, resulting in two inherent drawbacks: firstly, high energy consumption, making them unsuitable for deployment in low-power or mobile scenarios; and secondly, in hydrogen-rich environments, the high-temperature components of the sensor itself may constitute a potential ignition source, posing a safety hazard.

[0004] To overcome the aforementioned problems, existing technological improvements mainly focus on two aspects: first, developing novel catalysts with higher low-temperature activity to reduce the required reaction temperature; and second, reducing heating power consumption by optimizing the micro-hotplate structure design. Nevertheless, these solutions have not completely eliminated dependence on external heat sources, and still have significant shortcomings in achieving true room-temperature operation while maintaining high sensitivity and rapid response performance.

[0005] Therefore, the current technological system urgently needs a fundamental breakthrough to develop a new hydrogen sensor solution that can operate stably at room temperature without external heating and can simultaneously achieve efficient catalytic conversion and high-sensitivity detection. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a method for preparing a calorimetric hydrogen sensor that operates at room temperature, so as to achieve high sensitivity and fast response hydrogen detection without relying on external heating, while completely eliminating the high power consumption and safety hazards caused by the high temperature operation of traditional catalytic combustion sensors.

[0007] This invention provides a method for preparing a room-temperature operating calorimetric hydrogen sensor, comprising the following steps:

[0008] S1. Provides MEMS single-crystal silicon thermopile chips;

[0009] S2. Preparation of two-dimensional palladium metal olefin materials;

[0010] S3. The two-dimensional palladium metal olefin material described in step S2 is dispersed in a solvent to prepare a sensitive material dispersion, and then ultrasonically treated to form a uniformly dispersed and stable suspension system;

[0011] S4. Using a micro-spotting instrument, the sensitive material dispersion liquid described in step S3 is precisely spotted onto the hot-end sensitive area of ​​the MEMS single-crystal silicon thermopile chip described in step S1, ensuring that the sensitive material only covers the hot-end area without affecting the cold-end structure, so as to ensure the effectiveness and stability of thermoelectric output; during the spotting process, multiple layers can be loaded one by one, and a short period of settling is allowed after each spotting to improve the uniformity and adhesion of the sensitive layer;

[0012] S5. After the MEMS single-crystal silicon thermopile chip is spotted in step S4, place it in an oven to dry it in order to remove residual solvent and enhance the bonding force between the sensitive material and the thermopile surface.

[0013] S6. The MEMS single-crystal silicon thermopile chip dried in step S5 is subjected to aging treatment to obtain a calorimetric hydrogen sensor.

[0014] Furthermore, the structure of the MEMS single-crystal silicon thermopile chip in step S1 is the same as the structure of the MEMS differential thermal analysis sensor disclosed in invention patent CN116297647B.

[0015] Preferably, the preparation method of the two-dimensional palladium metal olefin material in step S2 is as follows: weigh 10-15 mg of palladium acetylacetonate and 20-30 mg of tungsten hexacarbonyl, add 8-10 mL of N,N-dimethylformamide and 2-5 mL of acetic acid in sequence, stir magnetically at room temperature for 10-20 min to obtain a uniform precursor solution, and then place it at 50-80 ℃ for constant temperature reaction for 1-2 h; after the reaction is completed, cool to room temperature, centrifuge, wash and dry to obtain the two-dimensional palladium metal olefin material.

[0016] Preferably, the solvent in step S3 is anhydrous ethanol or deionized water.

[0017] Preferably, the concentration of the sensitive material dispersion in step S3 is 1-5 mg·mL. -1 .

[0018] Preferably, the ultrasonic treatment time in step S3 is 10-30 min.

[0019] Preferably, the amount of the sensitive material dispersion in step S4 is 0.1-0.5 μL.

[0020] Preferably, the drying temperature in step S5 is 50-100 ℃ and the drying time is 1-2 h.

[0021] Preferably, the aging process in step S6 specifically involves aging the MEMS single-crystal silicon thermopile chip dried in step S5 at room temperature for 6-12 hours in air or a 100-500 ppm hydrogen atmosphere, so that the sensitive layer structure and interface gradually stabilize, thereby improving the repeatability, stability and long-term reliability of the sensor.

[0022] The present invention also provides a room-temperature calorimetric hydrogen sensor prepared according to the above preparation method.

[0023] Beneficial effects

[0024] (1) The present invention uses two-dimensional palladium metal olefin as a sensitive material, which can effectively respond to hydrogen at room temperature. Combined with MEMS single crystal silicon thermopile, detection can be completed without additional heating, which significantly reduces the overall power consumption of the sensor and improves the safety and environmental adaptability.

[0025] (2) The two-dimensional palladium metal olefin used in this invention has atomic-level thickness and a large area of ​​continuous metal surface, which significantly improves the adsorption and reaction efficiency of hydrogen on the material surface, enabling the sensor to obtain obvious and stable signal output at room temperature. Its room temperature response capability is better than that of existing palladium-based sensors. Attached Figure Description

[0026] Figure 1 This is a schematic diagram illustrating the principle of the calorimetric hydrogen sensor in this invention.

[0027] Figure 2 This is a TEM image of the two-dimensional palladium metalene in the calorimetric hydrogen sensor of Example 1.

[0028] Figure 3 The following is a characterization of the gas-sensing performance of the calorimetric hydrogen sensor in Example 1 at room temperature: (a) continuous dynamic response curves to hydrogen in the concentration range of 25 ppb-2%; (b) fitting relationship between sensor response value and hydrogen concentration; (c) response and recovery characteristics under 1% hydrogen conditions; (d) comparison of selective responses to different gases.

[0029] Figure 4 The image shows the TEM morphology of the platinum nanoparticles in Comparative Example 1 and their response recovery time to 1% hydrogen gas.

[0030] Figure 5 The image shows the TEM morphology of the palladium nanoparticles in Comparative Example 2 and their response recovery time to 1% hydrogen.

[0031] Figure 6 The image shows the TEM morphology of alumina-supported platinum nanoparticles in Comparative Example 3 and their response recovery time to 1% hydrogen. Detailed Implementation

[0032] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0033] like Figure 1 As shown, this invention introduces two-dimensional palladium metallene as a hydrogen-sensitive material, combining it with a MEMS single-crystal silicon thermopile chip to construct a hydrogen sensing system that can operate without high-temperature heating. Compared to zero-dimensional or three-dimensional palladium materials, the two-dimensional layered structure of palladium metallene possesses atomic-level thickness and a large-area continuous metal surface, exposing more active metal sites per unit mass or unit area that can participate in hydrogen adsorption and reaction. This allows hydrogen molecules to more fully contact the material surface and undergo adsorption or dissociation reactions at room temperature. This structural characteristic lowers the energy barrier for hydrogen to participate in surface reactions, facilitating the triggering of detectable signal changes without additional heating. The highly efficient catalysis and signal amplification of hydrogen by two-dimensional palladium metallene at room temperature enables the sensor to maintain fast response and high sensitivity while significantly reducing device energy consumption, thus achieving a room-temperature hydrogen detection technology that balances performance and energy efficiency.

[0034] Example 1

[0035] This embodiment provides a room-temperature operating calorimetric hydrogen sensor, the preparation method of which specifically includes the following steps:

[0036] S1. Provides MEMS single-crystal silicon thermopile chips;

[0037] S2. Preparation of two-dimensional palladium metal olefin materials;

[0038] (1) Preparation of precursor solution: Weigh 10 mg of palladium acetylacetone Pd(acac)2 and 20 mg of tungsten hexacarbonyl W(CO)6 and add them to a clean 20 mL glass reaction flask. Then add 8 mL of N,N-dimethylformamide (DMF) as the reaction solvent and stir magnetically to form a uniform and stable yellow transparent solution.

[0039] (2) Construction of reaction system: Under continuous stirring, 2 mL of acetic acid was slowly added dropwise to the above solution to obtain a reaction mixture.

[0040] (3) Low-temperature reaction to generate two-dimensional palladium metal olefin: The reaction mixture was placed in an oil bath environment and reacted at a constant temperature of 50 °C for 1 hour, and a black product was gradually generated in the system.

[0041] (4) Product separation and purification: After the reaction is completed, the solid product is collected by centrifugation and washed repeatedly with water and anhydrous ethanol to remove residual solvent and unreacted precursor.

[0042] (5) Drying treatment: The washed solid product is dried at 50 °C to obtain two-dimensional palladium metal olefin material.

[0043] S3. The above two-dimensional palladium metalene material was added to ethanol to prepare a sensitive material dispersion with a mass concentration of 5 mg / mL, and then sonicated for 30 min to form a uniformly dispersed and stable suspension system.

[0044] S4. Using a micro-sampling method, 0.3 μL of the sensitive material dispersion is precisely loaded into the sensitive hot end region of the MEMS single-crystal silicon thermopile chip, so that the two-dimensional palladium metalene is in full contact with the hot end of the thermopile and a stable catalytic sensitive layer is constructed.

[0045] S5. After spotting, the MEMS single-crystal silicon thermopile chip is placed in a constant temperature oven at 90 ℃ for 1 h to effectively remove residual solvent and enhance the adhesion stability between the sensitive material and the MEMS single-crystal silicon thermopile chip.

[0046] S6. After drying, the MEMS single-crystal silicon thermopile chip is aged in an air environment for 30 minutes to gradually stabilize the state of the sensitive material and its interface with the thermopile, thereby improving the repeatability and long-term reliability of the sensor in actual operation.

[0047] The prepared sensor was installed in a sealed test chamber, and hydrogen gas of different concentrations was introduced at room temperature to collect and analyze the device's output signal in real time. The typical morphology of the prepared two-dimensional palladium metalene ultrathin two-dimensional structure is shown in the figure. Figure 2 As shown, the overall gas-sensing response characteristics of the sensor based on the two-dimensional palladium metal olefin catalyst at room temperature are as follows: Figure 3 As shown in the diagram, it exhibits an ultra-wide linear detection range (25 ppb-2%), excellent gas selectivity, and rapid response and recovery characteristics. At room temperature, the response amplitude for 1% hydrogen is 414 mV, with response time and recovery time of 3.1 s and 2.9 s, respectively.

[0048] Comparative Example 1

[0049] In comparison, platinum nanoparticles (Pt NPs) were used instead of the two-dimensional palladium metalloene in Example 1 as the sensing material, and a calorimetric hydrogen sensor was prepared using the same method. Its performance was evaluated under the same testing conditions as in Example 1. The morphology and test results of the Pt NPs are as follows: Figure 4 As shown, the response amplitude to 1% hydrogen at room temperature is 4.5 mV, and the response time and recovery time are 34 s and 4.3 s, respectively.

[0050] Comparative Example 2

[0051] In comparison, palladium nanoparticles (Pd NPs) were used instead of the two-dimensional palladium metalloene in Example 1 as the sensing material, and a calorimetric hydrogen sensor was prepared using the same method. Its performance was evaluated under the same testing conditions as in Example 1. The morphology and test results of the Pd NPs are as follows: Figure 5 As shown, the response amplitude to 1% hydrogen at room temperature is 0.6 mV, and the response time and recovery time are 4.3 s and 4.1 s, respectively.

[0052] Comparative Example 3

[0053] In comparison, alumina-supported platinum nanoparticles (Pt NPs@Al2O3) were used instead of the two-dimensional palladium metalloene in Example 1 as the sensing material, and a calorimetric hydrogen sensor was prepared using the same method. Its performance was evaluated under the same testing conditions as in Example 1. The morphology and test results of Pt NPs@Al2O3 are as follows: Figure 6 As shown, the response amplitude to 1% hydrogen at room temperature is 6.2 mV, and the response time and recovery time are 5.2 s and 3.7 s, respectively.

[0054] Through the aforementioned preparation and assembly process, the controllable preparation of two-dimensional palladium metalene materials and their effective application in high-performance room-temperature hydrogen sensing were achieved. Results show that the hydrogen sensor using two-dimensional palladium metalene as a catalyst exhibits excellent comprehensive performance, possessing an ultra-wide detection range (25 ppb–2%), excellent gas selectivity, and rapid response and recovery characteristics. Compared with Pt NPs, Pd NPs, and Pt NPs@Al₂O₃ sensing materials, its response time is shortened by approximately 90.88%, 27.91%, and 40.38%, respectively, demonstrating a significant improvement in reaction kinetics. Furthermore, under 1% hydrogen concentration conditions, the response amplitude of this sensor is approximately 99 times, 749 times, and 74 times higher than that of Pt NPs, Pd NPs, and Pt NPs@Al₂O₃, respectively, further validating the outstanding application potential of two-dimensional palladium metalene in achieving high-sensitivity, high-performance room-temperature hydrogen sensing.

Claims

1. A method for preparing a room-temperature calorimetric hydrogen sensor, comprising the following steps: S1. Provides MEMS single-crystal silicon thermopile chips; S2. Preparation of two-dimensional palladium metal olefin materials; S3. The two-dimensional palladium metal olefin material described in step S2 is dispersed in a solvent to prepare a sensitive material dispersion, and then ultrasonically treated to form a uniformly dispersed and stable suspension system; S4. Using a micro-spotting instrument, the sensitive material dispersion liquid described in step S3 is precisely spotted onto the hot-end sensitive area of ​​the MEMS single-crystal silicon thermopile chip described in step S1. S5. Place the MEMS single-crystal silicon thermopile chip after the spotting in step S4 in an oven to dry; S6. The MEMS single-crystal silicon thermopile chip dried in step S5 is subjected to aging treatment to obtain a calorimetric hydrogen sensor.

2. The preparation method according to claim 1, characterized in that, The preparation method of the two-dimensional palladium metal olefin material in step S2 is as follows: 10-15 mg of palladium acetylacetonate and 20-30 mg of tungsten hexacarbonyl are weighed and added sequentially to 8-10 mL of N,N-dimethylformamide and 2-5 mL of acetic acid. The mixture is magnetically stirred at room temperature for 10-20 min to obtain a homogeneous precursor solution. The solution is then placed at 50-80 ℃ for a constant temperature reaction for 1-2 h. After the reaction is completed, the solution is cooled to room temperature, centrifuged, washed, and dried to obtain the two-dimensional palladium metal olefin material.

3. The preparation method according to claim 1, characterized in that, In step S3, the solvent is anhydrous ethanol or deionized water; the concentration of the sensitive material dispersion is 1-5 mg·mL. -1 .

4. The preparation method according to claim 1, characterized in that, The ultrasonic treatment time in step S3 is 10-30 minutes.

5. The preparation method according to claim 1, characterized in that, In step S4, the amount of the sensitive material dispersion sampled is 0.1-0.5 μL.

6. The preparation method according to claim 1, characterized in that, In step S5, the drying temperature is 50-100 ℃ and the drying time is 1-2 h.

7. The preparation method according to claim 1, characterized in that, The aging process in step S6 specifically involves aging the MEMS single-crystal silicon thermopile chip, which has been dried in step S5, at room temperature for 6-12 hours in an air or 100-500 ppm hydrogen atmosphere.

8. A room-temperature calorimetric hydrogen sensor prepared by the method according to claim 1.

Images