A method for manufacturing a catalyst and a membrane electrode for a fuel cell type sensor and applications thereof

Abstract

The application belongs to the technical field of electrochemical gas sensors, and discloses a preparation method and application of a catalyst and a membrane electrode of a fuel cell type sensor, wherein the catalyst for sensing H2S gas comprises a Ti3C2 carrier and Pt nanoparticles attached to the Ti3C2 carrier. The catalyst obtained by improving the composition of the catalyst comprises a Ti3C2 carrier and Pt nanoparticles attached to the Ti3C2 carrier, and can be used as a sensitive material for sensing H2S gas. The corresponding membrane electrode is composed of a Nafion membrane and a catalytic layer prepared by the catalyst on both sides. The sensor further constructed has low detection lower limit, excellent stability and sensitivity, wide detection range, and other comprehensive performances for hydrogen sulfide. The sensor has the advantages of no need to apply voltage, operation at room temperature, simple preparation, and the like, and has great application potential.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical gas sensor technology, and more specifically, relates to a method for preparing a catalyst and membrane electrode for a fuel cell sensor and its application. Background Technology

[0002] Hydrogen sulfide (H2S) is a toxic gas that is colorless, flammable, corrosive, and has a distinctive rotten egg odor. When inhaled, H2S severely irritates the mucous membranes and deprives the central nervous system of oxygen, leading to serious consequences such as suffocation and coma, posing a significant threat to human health. Low concentrations of H2S can damage the eyes, respiratory system, and central nervous system, while inhaling even small amounts of high concentrations can be fatal within a short period. According to OSHA (Occupational Safety and Health Administration) standards, the permissible exposure concentration under an 8-hour workday is 10 ppm, with an acceptable upper limit of 20 ppm. Therefore, real-time monitoring of H2S is crucial.

[0003] The proton exchange membrane-based fuel cell gas sensor is a novel electrochemical sensor. Unlike semiconductor and optical sensors, it can operate at room temperature without requiring an applied voltage, has very low power consumption, and is simple and inexpensive to fabricate, making it highly promising. The sensor works by the oxidation of hydrogen sulfide at the working electrode, producing protons and electrons. Protons are conducted through the proton exchange membrane to the counter electrode, while electrons are conducted through an external circuit to the counter electrode, where a reduction reaction occurs. The resulting current is linearly related to the gas concentration. Hydrogen sulfide is detected by measuring the current in the external circuit.

[0004] Electrode materials are a crucial factor affecting sensor performance. Traditional electrode materials are typically prepared by loading noble metals onto carbon supports (such as carbon fibers, carbon black, and mesoporous carbon). However, the weak bonding between the carbon support and the noble metal can easily lead to the detachment of the noble metal from the carbon support and the aggregation of the noble metal during sensor operation, resulting in decreased sensor performance and poor stability. To overcome this problem, it is essential to develop highly stable and high-performance catalyst materials. Summary of the Invention

[0005] To address the aforementioned deficiencies or improvement needs of existing technologies, the present invention aims to provide a method for preparing a catalyst and membrane electrode assembly (MEA) for a fuel cell sensor, as well as its application. By improving the composition of the catalyst, the resulting catalyst comprises a Ti3C2 support and Pt nanoparticles attached to the Ti3C2 support (hereinafter referred to as Pt / Ti3C2), which can be particularly used as a sensitive material for sensing H2S gas. This Pt / Ti3C2 is specifically formed by chemically reducing Pt nanoparticles onto Ti3C2. The corresponding MEA consists of a Nafion membrane and a catalytic layer prepared from catalysts on both sides. The sensor based on the Pt-modified transition metal carbide electrode layer prepared according to the present invention (i.e., an electrode layer constructed using Pt / Ti3C2 as the functional material) exhibits comprehensive performance characteristics such as a low detection limit for hydrogen sulfide, excellent stability and sensitivity, and a wide detection range. Furthermore, this sensor has advantages such as requiring no applied voltage, operating at room temperature, and simple preparation, making it highly promising for application.

[0006] To achieve the above objectives, according to one aspect of the present invention, a catalyst for sensing H2S gas is provided, characterized in that it comprises a Ti3C2 support and Pt nanoparticles attached to the Ti3C2 support.

[0007] As a further preferred embodiment of the present invention, the Pt nanoparticles are modified onto Ti3C2 by chemical reduction.

[0008] Preferably, the mass ratio of the Pt nanoparticles to the Ti3C2 support is (0.15-2):3.

[0009] According to another aspect of the present invention, the present invention provides a method for preparing the above-mentioned catalyst for sensing H2S gas, characterized by comprising the following steps:

[0010] S1: Mix Ti3C2 material with chloroplatinic acid solution and trisodium citrate to obtain solution A;

[0011] S2: Prepare a sodium hydroxide solution and add sodium borohydride to it to obtain solution B;

[0012] S3: Under stirring conditions, add solution B to solution A, then adjust the pH value to 6-7, and then heat in a water bath at 70℃-90℃ for 2-3 hours to obtain solution C;

[0013] S4: Solution C is subjected to a precipitate by static settling, centrifugation, or filtration. The precipitate is then washed and dried to obtain a catalyst for sensing H2S gas.

[0014] As a further preferred embodiment of the present invention, in step S1, the mass ratio between the Ti3C2 material and the platinum element in the chloroplatinic acid solution is (0.15-2):3, and the mass ratio between the trisodium citrate and the platinum element in the chloroplatinic acid solution is (1-4):1.

[0015] As a further preferred embodiment of the present invention, in step S1, the Ti3C2 material is first prepared by using the reactants to generate hydrofluoric acid to etch the Ti3AlC2 material, and then by annealing with hydrogen.

[0016] Preferably, the preparation method of the Ti3C2 material is as follows: Ti3AlC2 is added to a mixed solution of lithium fluoride and hydrochloric acid and stirred for 24-28 hours. Then the reactants are washed and dried, and the dried product is annealed with hydrogen at 300-600℃ to obtain the Ti3C2 material.

[0017] More preferably, the ratio of Ti3AlC2, lithium fluoride and hydrochloric acid is (0.5-2g: 1-2g: 20-40ml); in the mixed solution of lithium fluoride and hydrochloric acid, the concentration of hydrochloric acid is 9mol / L.

[0018] According to another aspect of the present invention, the present invention provides the application of the above-mentioned catalyst for sensing H2S gas as a sensing material in sensing H2S gas.

[0019] According to another aspect of the present invention, the present invention provides a fuel cell-type H2S gas sensor membrane electrode constructed based on the above-described catalyst for sensing H2S gas, characterized in that it includes a Nafion membrane and a catalyst layer located on both sides of the Nafion membrane; wherein the catalyst layer includes the above-described catalyst for sensing H2S gas.

[0020] According to another aspect of the present invention, the present invention provides a method for preparing the above-mentioned fuel cell-type H2S gas sensor membrane electrode, characterized by comprising the following steps:

[0021] (1) Prepare a clean Nafion membrane;

[0022] (2) The catalyst used for sensing H2S gas is prepared into an electrode slurry, coated on a polymer film and dried to obtain an electrode layer attached to the polymer film; then, the electrode layer is attached to both sides of the Nafion membrane in step (1) by hot pressing to obtain the membrane electrode of the fuel cell type H2S gas sensor.

[0023] As a further preferred embodiment of the present invention, in step (1), the clean Nafion membrane is obtained by a pretreatment process. The pretreatment specifically involves: placing the Nafion membrane in a water bath at 60-90°C for 1-2 hours in H2O2 solution, deionized water, H2SO4 solution and deionized water respectively, and then washing it.

[0024] Preferably, the concentration of the H2O2 solution is 5 wt%; and the concentration of the H2SO4 solution is 0.5 mol / L.

[0025] In step (2), the electrode slurry is specifically prepared by: preparing a dispersant by mixing 5-20 wt% Nafion aqueous solution, ethylene glycol and deionized water in a volume ratio of (1-5):(1-5):(5-10); then, adding the catalyst for sensing H2S gas to the dispersant and mixing evenly.

[0026] In step (2), the drying process specifically involves oven drying;

[0027] The hot-pressing method specifically involves hot-pressing a polymer film with an electrode layer attached onto both sides of a pretreated Nafion film at a temperature of 70–100°C and a pressure of 1–10 MPa, so that the electrode layer is in direct contact with the Nafion film and is maintained for 60–120 seconds. Then, the polymer film is peeled off, thereby attaching the electrode layer to both sides of the pretreated Nafion film.

[0028] According to the last aspect of the present invention, the present invention provides a fuel cell type H2S gas sensor, characterized in that its membrane electrode is the above-mentioned fuel cell type H2S gas sensor membrane electrode.

[0029] Compared with the prior art, the present invention can achieve the following beneficial effects through the above-described technical solutions:

[0030] (1) The catalyst Pt / Ti3C2 prepared in this invention exhibits excellent catalytic performance compared to traditional platinum-carbon materials. The two-dimensional layered structure of Ti3C2 provides abundant anchoring space and has rich surface chemical properties, which is beneficial for the loading of Pt nanoparticles; its excellent conductivity and structural stability can enhance the catalytic effect of Pt, thereby improving the redox reaction capability of gases; at the same time, there is a strong metal-support interaction between Pt and Ti3C2, which improves the stability of the sensor.

[0031] (2) In this invention, the preparation method of the catalyst Pt / Ti3C2 is simple and easy to implement. The hydrogen sulfide sensor using Pt / Ti3C2 as the catalyst has advantages such as a low detection limit, wide range, and good stability. As exemplified in Example 1 below, the sensor's detection limit can reach 10 ppb of hydrogen sulfide, and the detection concentration range is 10 ppb-200 ppm. Furthermore, the sensor's response recovery curve behavior remained good during the tests on days 10, 45, and 90, indicating that the sensor has excellent stability and features such as a low detection limit, wide range, and good stability.

[0032] In summary, this invention uses Pt nanoparticles to modify Ti3C2 as a catalyst, effectively solving the problems of low detection limit and poor stability of H2S gas sensors, and demonstrating significant advantages. Attached Figure Description

[0033] Figure 1 The images show the XRD patterns of the Ti3C2 material and Pt / Ti3C2 material prepared in Example 1 of this invention.

[0034] Figure 2 The images show SEM images of the Ti3C2 material and Pt / Ti3C2 material prepared in Example 1 of this invention; wherein, Figure 2 (a) in the text corresponds to Ti3C2 material. Figure 2 (b) in the text corresponds to the Pt / Ti3C2 material.

[0035] Figure 3 The response recovery curves of the Pt / Ti3C2 hydrogen sulfide sensor prepared in Example 1 and the Pt / C hydrogen sulfide sensor prepared in Comparative Example 1 to hydrogen sulfide ranging from 0.05 ppm to 200 ppm are shown.

[0036] Figure 4 The figures show the linear fitting curves between the response current and hydrogen sulfide concentration for the Pt / Ti3C2 hydrogen sulfide sensor prepared in Example 1 and the Pt / C hydrogen sulfide sensor prepared in Comparative Example 1. In the figures, taking the Pt / Ti3C2 hydrogen sulfide sensor prepared in Example 1 as an example, ΔI is the difference between the peak response current (e.g., a flat region) and the sensor's own current baseline; the linear fitting result is Y = 0.162x + 0.247, where Y is in μA and X is in ppm (i.e., H2S concentration); furthermore, for high concentrations of H2S, considering the existence of a certain reaction time, the highest value of the response current is taken. The linear fitting result for the Pt / C hydrogen sulfide sensor prepared in Comparative Example 1 is Y = 0.112x + 0.420.

[0037] Figure 5The graphs show the change in the response current value of the Pt / Ti3C2 hydrogen sulfide sensor prepared in Example 1 and the Pt / C hydrogen sulfide sensor prepared in Comparative Example 1 over 90 days in response to 50 ppm hydrogen sulfide (tested every five days).

[0038] Figure 6 The image shows the response recovery curves of the Pt / Ti3C2 hydrogen sulfide sensor prepared in Example 1 of this invention to 10ppb-50ppb hydrogen sulfide.

[0039] Figure 7 The response recovery curves of the Pt / Ti3C2 hydrogen sulfide sensor prepared in Example 1 of this invention to 50 ppm hydrogen sulfide on days 10, 45, and 90 are shown.

[0040] Figure 8 The figures show the response recovery curves of the Pt(10%) / Ti3C2 hydrogen sulfide sensor prepared in Example 1 and the Pt(5%) / Ti3C2 hydrogen sulfide sensor prepared in Example 2 under 50 ppm hydrogen sulfide. The Pt(10%) / Ti3C2 hydrogen sulfide sensor prepared in Example 1 corresponds to the Pt(5%) / Ti3C2 hydrogen sulfide sensor in the figure. 10 / Ti3C2, the corresponding diagram of the Pt(5%) / Ti3C2 hydrogen sulfide sensor prepared in Example 2 is Pt5 / Ti3C2.

[0041] Figure 9 The response recovery curve of the Pt / SnO2-Pd sensor prepared in Comparative Example 2 to 50ppm H2S is shown.

[0042] Figure 10 The response recovery curve of the Pt / WO3-Pd sensor prepared in Comparative Example 3 to 50ppm H2S is shown. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0044] Example 1

[0045] 1. Pretreatment of the proton exchange membrane: Using a Nafion 115 membrane as the proton exchange membrane, the membrane was subjected to a water bath at 80℃, sequentially in H2O2 solution (5wt%), deionized water, H2SO4 solution (0.5mol / L), and deionized water for 1 hour. Finally, the membrane was rinsed 3–5 times with deionized water, and the treated Nafion membrane was then sealed and stored in deionized water.

[0046] 2. Preparation of Ti3C2: 1g of lithium fluoride and 20ml (9M) hydrochloric acid were mixed in a polytetrafluoroethylene beaker and stirred for 20 minutes. Then, 1g of Ti3AlC2 was slowly added, and the mixture was reacted at 25℃ for 48 hours. The product was then centrifuged, washed, and dried multiple times. The resulting powder was then subjected to hydrogen annealing at 350℃ to obtain the target Ti3C2 material.

[0047] 3. Preparation of catalyst Pt(10%) / Ti3C2

[0048] a. Take 450 mg of Ti3C2 material, add 5.12 ml of 50 mM chloroplatinic acid solution, then add water to 20 ml, stir for 20 minutes, add 150 mg of trisodium citrate, and stir for 20 minutes. In the system, the mass ratio of platinum to Ti3C2 material is 10%:1.

[0049] b. Dissolve 0.1g of sodium hydroxide in 25ml of deionized water to form an alkaline solution. Then add 0.015g of sodium borohydride (the amount of sodium borohydride needs to be in excess, and its amount needs to be greater than or equal to twice the amount of Pt in the chloroplatinic acid solution), and stir for 20 minutes. Slowly add the resulting solution dropwise to the solution in step a until the pH of the solution is about 7, and stir in an 80℃ water bath for 2 hours.

[0050] c. Let the solution obtained in step b stand for 6 hours, pour off the upper waste liquid, wash the precipitate with deionized water 4 times by centrifugation, and then dry it under vacuum at 60°C for 12 hours to obtain Pt(10%) / Ti3C2 material.

[0051] 4. Membrane electrode preparation

[0052] Take 10 mg of Pt(10%) / Ti3C2 powder and mix it with 100 μL of dispersant (ethylene glycol, 5 wt% Nafion solution, and deionized water in a volume ratio of 2:1:4) ultrasonically for 60 min to obtain an electrode slurry. Drop the slurry onto a 1 cm x 1 cm polytetrafluoroethylene (PTFE) film (other polymer films, such as polyvinylidene fluoride (PVDF) or polypropylene (PP) films, which are fixed with tape, using a pipette. Coat the slurry evenly with a scraper, dry at 65°C, remove the film, and remove the tape to obtain a PTFE film with a fixed electrode layer material. Remove the Nafion film from the deionized water after the pretreatment in step 1 and dry it. Then, hot-press two PTFE films with sensitive material onto both sides of the Nafion film at 90°C, 6 MPa, and 90 s (the surface coated with the electrode layer material is in direct contact with the Nafion film). Peel off the PTFE film to obtain the membrane electrode.

[0053] 5. Sensor Assembly

[0054] The sensor structure, from top to bottom, consists of leads, current collector, membrane electrode assembly, current collector again, and back cover. It is tightly sealed with sealant to obtain a fuel cell-type gas sensor.

[0055] Assemble the membrane electrode obtained in step 4 according to the above structure to obtain a fuel cell type hydrogen sulfide gas sensor (i.e., Pt / Ti3C2 hydrogen sulfide sensor).

[0056] 6. Sensor Testing

[0057] The sensor was tested at room temperature using a static gas mixing method. The sensor was connected to an electrochemical workstation, and the generated current was measured using a zero-resistance ammeter method. Different concentrations of hydrogen sulfide were prepared for testing the sensor, and the results are as follows: Figures 3 to 8 The sensor exhibited excellent response recovery curves at different concentrations (0.05ppm-200ppm), with a very high linear relationship between the response value and the hydrogen sulfide concentration. Furthermore, the sensor could detect hydrogen sulfide as low as 10ppb. Simultaneously, the prepared Pt / Ti3C2 hydrogen sulfide sensor was stored in a laboratory environment (temperature: 23±3℃, humidity: 60±5%RH), and the response current to 50ppm hydrogen sulfide was tested every five days. The results showed that the sensor had excellent stability, as demonstrated by the response recovery curves at days 10, 45, and 90. This indicates that the fuel cell-type hydrogen sulfide sensor prepared based on the catalyst Pt(10%) / Ti3C2 and its membrane electrode exhibits excellent performance in hydrogen sulfide detection and has great application potential.

[0058] Example 2

[0059] 1. Pretreatment of the proton exchange membrane: Refer to Example 1 above.

[0060] 2. Preparation of Ti3C2: Refer to Example 1 above.

[0061] 3. Preparation of catalyst Pt (5%) / Ti3C2

[0062] a. Take 475 mg of Ti3C2 material, add 2.56 ml of 50 mM chloroplatinic acid solution, then add water to 20 ml, stir for 20 minutes, add 150 mg of trisodium citrate, and stir for 20 minutes. In the system, the mass ratio of platinum to Ti3C2 material is 5%:1.

[0063] b. Dissolve 0.1g of sodium hydroxide in 25ml of deionized water to form an alkaline solution, then add 0.015g of sodium borohydride and stir for 20 minutes. Slowly add the resulting solution dropwise to the solution from step a until the pH of the solution is approximately 7, then stir in an 80℃ water bath for 2 hours.

[0064] c. Let the solution obtained in step b stand for 6 hours, pour off the upper waste liquid, wash the precipitate with deionized water 4 times by centrifugation, and then dry it under vacuum at 60°C for 12 hours to obtain Pt(5%) / Ti3C2 material.

[0065] 4. Membrane electrode preparation: Refer to Example 1.

[0066] 5. Sensor assembly: Refer to Example 1.

[0067] 6. Sensor testing: The testing method is the same as in Example 1. The results show that the Pt(5%) / Ti3C2-based sensor has a resistance of 3.1 μA to 50 ppm H2S and good recovery performance (although its sensor performance is not as good as that of the Pt(10%) / Ti3C2 sensor).

[0068] Comparative Example 1

[0069] 1. Pretreatment of the proton exchange membrane: Refer to Example 1 above.

[0070] 2. The electrode material was a commercially available platinum-carbon (Pt(10%) / C) product, specifically purchased from Suzhou Shengernuo Technology Co., Ltd., model SPT10. This Pt(10%) / C platinum-carbon product has a platinum element to carbon material mass ratio of 10%:1.

[0071] Membrane electrode preparation: Refer to Example 1.

[0072] Sensor assembly: Refer to Example 1.

[0073] Referring to the sensor test in Example 1, the device prepared in Comparative Example 1 was tested under the same conditions.

[0074] After testing, such as Figure 3 and Figure 4 As shown, the sensor based on Pt(10%) / C has a lower response to H2S current than the sensor based on Pt(10%) / Ti3C2. Figure 4 For example, the linear fitting result between the response current and hydrogen sulfide concentration of the Pt / Ti3C2 hydrogen sulfide sensor prepared in Example 1 is Y = 0.162x + 0.247, while the linear fitting result of the Pt / C hydrogen sulfide sensor prepared in Comparative Example 1 is Y = 0.112x + 0.420. The slope of the fitting curve in Example 1 is higher, indicating that under the same change in hydrogen sulfide concentration, the change in response current will be more obvious and the sensor will be more sensitive. Figure 5As shown, the stability of the Pt(10%) / C-based sensor is also inferior to that of the Pt(10%) / Ti3C2-based sensor. The response current value of the Pt(10%) / Ti3C2-based sensor is more stable, while the response current value of the Pt(10%) / C-based sensor shows a significant decreasing trend. This indicates that the Pt / Ti3C2 catalyst prepared in this invention has superior catalytic performance and stability compared to traditional platinum-carbon materials.

[0075] Comparative Example 2

[0076] Referring to the Pt / SnO2-Pd material in the text of Chinese patent application No. 202210966479.9:

[0077] 1. Pretreatment of the proton exchange membrane: Refer to Example 1 above.

[0078] 2. Preparation of Pt / SnO2-Pd materials

[0079] a. Take 300 mg SnO2 and 1.12 mg dichlorotetraamminepalladium monohydrate, add 200 ml deionized water, stir at room temperature for 48 hours, centrifuge and wash, and dry at 65 °C; place the dried sample in a muffle furnace and anneal at 800 °C for 5 hours to obtain SnO2-Pd powder.

[0080] b. Take 10 mg of SnO2-Pd powder, add 10.5 ml of 50 mmol H2PtCl6 solution, stir for 10 min, add 0.3 mg of trisodium citrate, and stir for 30 min. Take 0.2 g of NaOH, dissolve it in 50 ml of deionized water, add 0.05 g of sodium borohydride, and test the pH to 13 to obtain an alkaline aqueous solution of sodium borohydride. Under ice-water bath conditions, use a pipette to add the alkaline aqueous solution of sodium borohydride dropwise to the above solution. After the addition is complete, stir in an 80°C water bath for 2 hours. Wash three times each with ethanol and deionized water by centrifugation, and dry at 65°C for 12 hours to obtain the Pt / SnO2-Pd electrode material.

[0081] Membrane electrode fabrication:

[0082] Referring to Example 2 in the text of Chinese patent application No. 202210966479.9, a membrane material containing a Pt / SnO2-Pd electrode was prepared using the membrane preparation method of Example 2.

[0083] Sensor assembly: Refer to Example 1.

[0084] Testing revealed that using a Pt / SnO2-Pd sensitive electrode, with a Pt element:SnO2-Pd powder mass ratio of 10:1, the current response to 50ppm H2S was low, and the sensor could not recover to baseline after venting (e.g., Figure 9As shown in the figure, it is not suitable for the detection of hydrogen sulfide.

[0085] Comparative Example 3

[0086] Refer to the Pt / WO3-Pd material in the text of Chinese patent application No. 202311116378.3:

[0087] 1. Pretreatment of the proton exchange membrane: Refer to Example 1 above.

[0088] 2. Preparation of Pt / WO3-Pd materials

[0089] a. Take 100 mg of WO3 powder and add it to 20 ml of ethanol, then sonicate for 10 minutes. Next, add 410 μL of 40 mM H2PdCl4 solution and stir at room temperature for 2 hours. The product obtained above is washed three times by centrifugation with deionized water and ethanol, and dried at 65 °C for 10 hours to obtain a solid product. Finally, place the obtained solid powder in a muffle furnace, set the heating rate to 5 °C / min, and hold at 400 °C for 2 hours. After annealing, WO3-Pd powder is obtained.

[0090] b. Take 10 mg of WO3-Pd powder, add 10.5 ml of 50 mmol H2PtCl6 solution, stir for 10 min, add 0.3 mg of trisodium citrate, and stir for 30 min. Take 0.2 g of NaOH, dissolve it in 50 ml of deionized water, add 0.05 g of sodium borohydride, and test the pH to 13 to obtain an alkaline aqueous solution of sodium borohydride. Under ice-water bath conditions, use a pipette to add the alkaline aqueous solution of sodium borohydride dropwise to the above solution. After the addition is complete, stir in an 80°C water bath for 2 hours. Wash three times each with ethanol and deionized water by centrifugation, and dry at 65°C for 12 hours to obtain the Pt / WO3-Pd electrode material.

[0091] Membrane electrode fabrication:

[0092] Referring to Example 2 in the text of Chinese patent application No. 202311116378.3, a membrane material containing a Pt / WO3-Pd electrode was prepared using the membrane preparation method of Example 2.

[0093] Sensor assembly: Refer to Example 1.

[0094] Tests showed that using a Pt / WO3-Pd sensitive electrode with a Pt element:WO3-Pd powder mass ratio of 10:1, the response to 50ppm H2S was only 0.85μA, indicating poor hydrogen sulfide gas sensitivity.

[0095] From the test results of the devices obtained in the above embodiments and comparative examples under 50ppm H2S responsiveness testing, it is easy to see that:

[0096] like Figure 8 As shown, whether it is the Pt(10%) / Ti3C2 hydrogen sulfide sensor prepared in Example 1 or the Pt(5%) / Ti3C2 hydrogen sulfide sensor prepared in Example 2, they need to be able to recover effectively and have a high current response; the Pt(5%) / Ti3C2 hydrogen sulfide sensor prepared in Example 2 has a current response ΔI of about 3.1 μA under the condition of 5% Pt content.

[0097] like Figure 9 As shown, the Pt / SnO2-Pd sensor prepared in Comparative Example 2 could not be recovered.

[0098] like Figure 10 As shown, the Pt / WO3-Pd sensor prepared in Comparative Example 3 has a low current response, with ΔI below 1.0 μA.

[0099] The above embodiments are merely examples. For instance, the pretreatment step for the Nafion membrane is optional, or it can be used directly without treatment (of course, the pretreatment step can further remove any impurities and foreign matter that may be present).

[0100] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. The application of a catalyst for sensing H2S gas as a sensing material in sensing H2S gas and lowering the detection limit of H2S, wherein the catalyst for sensing H2S gas comprises a Ti3C2 support and Pt nanoparticles attached to the Ti3C2 support. in, The catalyst for sensing H2S gas is prepared by a method comprising the following steps: S1: Mix Ti3C2 material with chloroplatinic acid solution and trisodium citrate to obtain solution A; S2: Prepare a sodium hydroxide solution and add sodium borohydride to it to obtain solution B; S3: Under stirring conditions, add solution B to solution A, then adjust the pH value to 6~7, and then heat in a water bath at 70℃-90℃ for 2-3 hours to obtain solution C; S4: Solution C is subjected to a precipitate by static settling, centrifugation, or filtration. The precipitate is then washed and dried to obtain a catalyst for sensing H2S gas.

2. The application as described in claim 1, characterized in that, In the catalyst used for sensing H2S gas, the mass ratio of the Pt nanoparticles to the Ti3C2 support is (0.15-2):

3.

3. The application as described in claim 1, characterized in that, In step S1, the mass ratio between the Ti3C2 material and the platinum element in the chloroplatinic acid solution is (0.15-2):3, and the mass ratio between the trisodium citrate and the platinum element in the chloroplatinic acid solution is (1-4):

1.

4. The application as described in claim 1, characterized in that, In step S1, the Ti3C2 material is first prepared by using the reactants to generate hydrofluoric acid to etch the Ti3AlC2 material, and then by annealing it with hydrogen.

5. The application as described in claim 4, characterized in that, In step S1, the preparation method of the Ti3C2 material is as follows: Ti3AlC2 is added to a mixed solution of lithium fluoride and hydrochloric acid and stirred for 24-28 hours. Then the reactants are washed and dried, and the dried product is annealed with hydrogen at 300-600℃ to obtain the Ti3C2 material.

6. The application as described in claim 5, characterized in that, The ratio of Ti3AlC2, lithium fluoride, and hydrochloric acid is 0.5-2g:1-2g:20-40ml; the concentration of hydrochloric acid in the lithium fluoride and hydrochloric acid mixed solution is 9mol / L.

7. The application as described in claim 1, characterized in that, The catalyst used for sensing H2S gas is applied in the form of a membrane electrode assembly for a fuel cell-type H2S gas sensor. The membrane electrode assembly for the fuel cell-type H2S gas sensor includes a Nafion membrane and catalyst layers located on both sides of the Nafion membrane; wherein the catalyst layers include the catalyst used for sensing H2S gas.

8. The application as described in claim 7, characterized in that, The membrane electrode of the fuel cell-type H2S gas sensor is prepared by a method including the following steps: (1) Prepare a clean Nafion membrane; (2) The catalyst for sensing H2S gas is prepared into an electrode slurry, coated on a polymer film and dried to obtain an electrode layer attached to the polymer film; then, the electrode layer is attached to both sides of the Nafion membrane in step (1) by hot pressing to obtain the membrane electrode of the fuel cell type H2S gas sensor.

9. The application as described in claim 8, characterized in that, In step (1), the clean Nafion membrane is obtained through a pretreatment process. The pretreatment process specifically involves: placing the Nafion membrane in a water bath at 60-90°C for 1-2 hours in H2O2 solution, deionized water, H2SO4 solution, and deionized water, respectively, and then washing it. In step (2), the electrode slurry is specifically prepared by mixing 5-20 wt% Nafion aqueous solution, ethylene glycol and deionized water in a volume ratio of (1-5):(1-5):(5-10) to form a dispersant; then, the catalyst for sensing H2S gas is added to the dispersant and mixed evenly. In step (2), the drying process specifically involves oven drying; The hot-pressing method specifically involves hot-pressing a polymer film with an electrode layer attached onto both sides of a pretreated Nafion film at a temperature of 70–100°C and a pressure of 1–10 MPa, so that the electrode layer is in direct contact with the Nafion film and is maintained for 60–120 seconds. Then, the polymer film is peeled off, thereby attaching the electrode layer to both sides of the pretreated Nafion film.

10. The application as described in claim 9, characterized in that, The concentration of the H2O2 solution is 5 wt%; the concentration of the H2SO4 solution is 0.5 mol / L.

11. A fuel cell-type H2S gas sensor for reducing the detection limit of H2S, characterized in that, Its membrane electrode includes a Nafion membrane and a catalyst layer located on both sides of the Nafion membrane; wherein, the catalyst layer includes a catalyst for sensing H2S gas; the catalyst for sensing H2S gas includes a Ti3C2 support and Pt nanoparticles attached to the Ti3C2 support; The catalyst used for sensing H2S gas is prepared by a method comprising the following steps: S1: Mix Ti3C2 material with chloroplatinic acid solution and trisodium citrate to obtain solution A; S2: Prepare a sodium hydroxide solution and add sodium borohydride to it to obtain solution B; S3: Under stirring conditions, add solution B to solution A, then adjust the pH value to 6~7, and then heat in a water bath at 70℃-90℃ for 2-3 hours to obtain solution C; S4: Solution C is subjected to a precipitate by static settling, centrifugation, or filtration. The precipitate is then washed and dried to obtain a catalyst for sensing H2S gas.

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