A Pt / CrWN2 gas-sensitive electrode material, its preparation method and application

Abstract

The application belongs to the technical field of novel gas sensitive electrode materials, and particularly relates to a Pt / CrWN2 gas sensitive electrode material and a preparation method and application thereof. The CrWN2 material with the advantages of binary transition metal nitride is synthesized by a hydrothermal-ammonolysis combined method, and Pt nanoparticles are loaded on the surface of the nitride to synthesize the Pt / CrWN2 gas sensitive electrode material. The preparation method of the Pt / CrWN2 gas sensitive electrode material has the advantages of short reaction time, simple operation and excellent material performance. The Pt / CrWN2 gas sensitive electrode material can be used for preparing a gas sensor, and the gas sensor has excellent long-term stability and rapid response recovery performance, and has important application value.

Description

Technical Field

[0001] This invention belongs to the technical field of novel gas-sensitive electrode materials, specifically relating to a Pt / CrWN2 gas-sensitive electrode material, its preparation method, and its application. Background Technology

[0002] Hydrogen sulfide is a colorless, toxic, flammable gas with a pungent odor. It is extremely toxic and can have very serious, even fatal, effects on human health. Therefore, rapid, accurate, and long-term stable monitoring of hydrogen sulfide can effectively prevent its threat to human health.

[0003] Traditional (PEM) fuel cell gas sensors often use porous carbon as a support, carrying Pt particles as a catalyst. Under electrochemical oxidation conditions, porous carbon is easily corroded and decomposed to form carbon oxides, causing Pt particles to aggregate. This reduces the number of active sites for Pt, significantly decreasing sensor sensitivity or even causing sensor failure. Developing more sensitive, efficient, and stable fuel cell sensors remains a significant challenge. Transition metal nitrides (TMNs) are considered to have great potential as support materials in fuel cell gas sensors due to their strong corrosion resistance, high conductivity, stable electrochemical performance, and strong interactions with noble metals. Currently, reports on ternary transition metal nitrides as support materials are very rare. Therefore, ternary transition metal nitrides, which combine the advantages of binary transition metal nitrides, hold promise for future applications as support materials in gas sensors. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the first objective of this invention is to provide a Pt / CrWN2 gas-sensitive electrode material, which possesses sensitive sensing performance.

[0005] The second objective of this invention is to provide a method for preparing the above-mentioned Pt / CrWN2 gas-sensitive electrode material, which has the advantages of short reaction time, simple operation and excellent material properties.

[0006] The third objective of this invention is to provide an application of the aforementioned Pt / CrWN2 gas-sensitive electrode material, which can be used to prepare gas sensors that possess excellent long-term stability and rapid response and recovery performance.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A Pt / CrWN2 gas-sensitive electrode material is prepared by loading Pt onto a CrWN2 carrier material; the particle size of the Pt / CrWN2 gas-sensitive electrode material is 15-25 nm.

[0009] The preparation method of the above-mentioned Pt / CrWN2 gas-sensitive electrode material comprises the following steps:

[0010] (1) Take chromium source, tungsten source and urea, add deionized water, sonicate and carry out hydrothermal reaction to obtain CrWN2 precursor;

[0011] (2) The CrWN2 precursor obtained in step (1) is heated in an ammonia atmosphere to obtain the product CrWN2.

[0012] (3) Take ethylene glycol, add the CrWN2,H2PtCl6 solution obtained in step (2), sonicate, and heat to obtain the Pt / CrWN2 gas-sensitive electrode material.

[0013] Furthermore, in step (1), the chromium source is chromium chloride hexahydrate, and the tungsten source is sodium tungstate dihydrate.

[0014] Further, in step (1), the molar volume ratio of the chromium source, tungsten source, urea and deionized water is (1-4) mol: (1-4) mol: 4 mol: 50 mL.

[0015] Furthermore, in step (1), the hydrothermal reaction is carried out at a temperature of 140°C for 3 hours.

[0016] Furthermore, in step (1), the ultrasonic treatment time is 30 minutes.

[0017] Furthermore, in step (1), after the hydrothermal reaction is completed, filtration, washing, and drying are required.

[0018] Furthermore, the drying temperature is 60°C, and the time is 8-12 hours.

[0019] Furthermore, in step (2), the heating rate is 5℃ / min, the temperature is 800℃, and the time is 8h.

[0020] Furthermore, in step (2), after the heating is completed, it is necessary to cool to room temperature and then introduce argon gas.

[0021] Furthermore, in step (3), the concentration of the H2PtCl6 solution is 100 mg / L.

[0022] Further, in step (3), the mass-to-volume ratio of the CrWN2, H2PtCl6 solution and ethylene glycol is 5 mg: 34 μL: 5 mL.

[0023] Furthermore, in step (3), the ultrasonic treatment time is 30 minutes.

[0024] Furthermore, in step (3), the heating reaction is carried out at a temperature of 140°C for 3 hours.

[0025] Furthermore, in step (3), after the heating reaction is completed, cooling, washing and drying are also required.

[0026] Furthermore, the drying temperature is 60°C, and the time is 8-12 hours.

[0027] The above-mentioned Pt / CrWN2 gas-sensitive electrode material can be used to prepare gas sensors.

[0028] Furthermore, the gas sensor can be used to detect H2S gas.

[0029] This invention utilizes a combined hydrothermal-ammonialysis method to prepare CrWN2. The obtained CrWN2 sample exhibits a nano-packed structure with a particle size of approximately 15-25 nm and a complete morphology. It is then coupled with the noble metal Pt to synthesize Pt / CrWN2 gas-sensitive electrode material. First, a precursor for nitrides, namely hydroxide, is synthesized using a hydrothermal method. Then, through ammonialysis, the precursor is nitrided at high temperature to form a transition metal nitride, which is then applied to the preparation technology of gas sensor carrier materials.

[0030] This invention utilizes the strong interaction between transition metal nitrides and Pt to alter the electronic structure of Pt atoms, causing predictable changes in the adsorption energy, activation energy, and electron transfer pathways of the catalyst support for different gases. This results in gas sensors exhibiting better sensitivity, selectivity, and stability.

[0031] Beneficial effects

[0032] This invention utilizes a combined hydrothermal-ammonialysis method to prepare CrWN2. The obtained CrWN2 sample exhibits a nano-packed structure with a particle size of approximately 15-25 nm and a complete morphology. Furthermore, it incorporates the noble metal Pt to synthesize Pt / CrWN2 gas-sensitive electrode material. This method features short reaction time, simple operation, and excellent material properties, making it a simple and efficient method for preparing ternary transition metal nitrides.

[0033] This invention uses Pt / CrWN2 gas-sensitive electrode material to prepare a gas sensor, which enables the gas sensor to have excellent long-term stability and fast response and recovery performance. Attached Figure Description

[0034] Figure 1 The images show the XRD patterns of the CrWN2 material and the Pt / CrWN2 material prepared in Example 1. Figure 1 (a) is the XRD pattern of the CrWN2 material prepared in Example 1. Figure 1 (b) is the XRD pattern of the Pt / CrWN2 material prepared in Example 1;

[0035] Figure 2 The images show SEM images of the CrWN2 material and Pt / CrWN2 material prepared in Example 1. Figure 2 (a) is a SEM image of the CrWN2 material prepared in Example 1. Figure 2 (b) is a SEM image of the Pt / CrWN2 material prepared in Example 1;

[0036] Figure 3 A statistical graph of selective test data for the Pt / CrWN2 gas sensor;

[0037] Figure 4 Statistical graph of response recovery test data for Pt / CrWN2 gas sensor;

[0038] Figure 5 A statistical chart of stability data for the Pt / CrWN2 gas sensor;

[0039] Figure 6 Comparison chart of tests using Pt / CrWN2 sensors with different ratios. Detailed Implementation

[0040] The following is a detailed implementation process of this invention patent.

[0041] Example 1

[0042] (1) Take 3 mmol of chromium chloride hexahydrate (CrCl3·6H2O), 1 mmol of sodium tungstate dihydrate (Na2WO4·2H2O), and 4 mmol of urea and put them into a 100 mL beaker with a raw material molar ratio of 3:1:4. Then add 50 mL of deionized water to the beaker. Place the beaker in an ultrasonic instrument and sonicate for 30 min. Transfer the mixed solution into a 100 mL polytetrafluoroethylene-lined container and place it in a stainless steel high-pressure reactor. React at 140 °C for 3 h in an oven. After naturally cooling to room temperature, centrifuge to collect the reactants. The centrifugation conditions are: speed: 9000 r / min, time: 5 min. Wash the collected sample with deionized water 3 times, centrifuging each time. Then wash the sample with anhydrous ethanol 3 times, centrifuging each time. Place the collected sample in a vacuum drying oven and dry at 60 °C for 8-12 h to obtain a light green powdery solid, which is the CrWN2 precursor.

[0043] (2) Take 200 mg of CrWN2 precursor into a ceramic boat and shake it to disperse it evenly. Then place the ceramic boat into a tube furnace and heat it to 800℃ at 5℃ / min under an ammonia atmosphere and maintain it for 8h. After the program is completed, let it cool naturally to room temperature, and then purge it with argon for 1h to ensure that NH3 is completely removed. Finally, the product CrWN2 material is obtained.

[0044] (3) Add 50 mg CrWN2 and 340 μL of H2PtCl6 solution with a mass concentration of 100 mg / L to 50 mL of ethylene glycol. Sonicate for 30 min until the mixture is homogeneous. Then transfer the mixture into a polytetrafluoroethylene liner and into a stainless steel high-pressure reactor. Place it in an oven and heat at 140 °C for 3 h. After it cools naturally to room temperature, centrifuge to collect the reactants. The centrifugation conditions are: speed: 9000 r / min, time: 5 min. Dry in a vacuum drying oven at 60 °C for 8-12 h. Wash the collected sample with deionized water 3 times, centrifuging each time. Then wash the sample with anhydrous ethanol 3 times, centrifuging each time. Place the collected sample in a vacuum drying oven and dry at 60 °C for 8-12 h to obtain a black powdery solid, which is the total product Pt / CrWN2 material.

[0045] Figure 1 The images show the XRD patterns of the CrWN2 material and the Pt / CrWN2 material prepared in Example 1. Figure 1 (a) is the XRD pattern of the CrWN2 material prepared in Example 1. Figure 1 (b) is the XRD pattern of the Pt / CrWN2 material prepared in Example 1; the results show that the CrWN2 material exhibits a nano-packed structure with a particle size of about 20 nm and a complete morphology; the Pt / CrWN2 material exhibits a particle packing structure with a particle size of 15-25 nm.

[0046] Figure 2 The images show SEM images of the CrWN2 material and Pt / CrWN2 material prepared in Example 1. Figure 2 (a) is a SEM image of the CrWN2 material prepared in Example 1. Figure 2 (b) is a SEM image of the Pt / CrWN2 material prepared in Example 1; the results show that the image clearly shows that CrWN2 formed a nanoparticle stack with a particle size of about 15-25 nm.

[0047] Example 2

[0048] (1) Modify the amount of chromium chloride hexahydrate in step (1) of Example 1 to 2 mmol, modify the amount of sodium tungstate dihydrate to 2 mmol, and keep the other conditions and steps the same as in step (1) of Example 1 to obtain black non-pure CrWN2 material.

[0049] (2) Same as step (2) in Example 1;

[0050] (3) Same as step (3) in Example 1.

[0051] Example 3

[0052] (1) Modify the amount of chromium chloride hexahydrate in step (1) of Example 1 to 1 mmol, modify the amount of sodium tungstate dihydrate to 3 mmol, and keep the other conditions and steps the same as in step (1) of Example 1 to obtain black non-pure CrWN2 material.

[0053] (2) Same as step (2) in Example 1;

[0054] (3) Same as step (3) in Example 1.

[0055] Example 4

[0056] (1) Same as step (1) in Example 1;

[0057] (2) Modify the heating temperature “800℃” in step (2) of Example 1 to “700℃”, and keep the other conditions and steps the same as in step (2) of Example 1 to obtain black non-pure CrWN2 material;

[0058] (3) Same as step (3) in Example 1.

[0059] Example 5

[0060] (1) Same as step (1) in Example 1;

[0061] (2) Modify the heating temperature “800℃” in step (2) of Example 1 to “900℃”, and keep the other conditions and steps the same as in step (2) of Example 1 to obtain black non-pure CrWN2 material;

[0062] (3) Same as step (3) in Example 1.

[0063] Example 6

[0064] (1) Same as step (1) in Example 1;

[0065] (2) Modify the heating time “8h” in step (2) of Example 1 to “6h”, and keep the other conditions and steps the same as in step (2) of Example 1 to obtain black non-pure CrWN2 material;

[0066] (3) Same as step (3) in Example 1.

[0067] Example 7

[0068] (1) Same as step (1) in Example 1;

[0069] (2) Modify the heating time “8h” in step (2) of Example 1 to “7h”, and keep the other conditions and steps the same as in step (2) of Example 1 to obtain black non-pure CrWN2 material;

[0070] (3) Same as step (3) in Example 1.

[0071] Comparative Example 1

[0072] (1) In step (1) of Example 1, the amount of chromium chloride hexahydrate was changed to 0 mmol, the amount of sodium tungstate dihydrate was changed to 4 mmol, and the other conditions and steps were the same as in step (1) of Example 1. No reaction occurred and no CrWN2 precursor material was generated.

[0073] No steps (2) and (3).

[0074] Comparative Example 2

[0075] (1) Modify the amount of chromium chloride hexahydrate in step (1) of Example 1 to 4 mmol, modify the amount of sodium tungstate dihydrate to 0 mmol, and keep the other conditions and steps the same as in step (1) of Example 1 to obtain black CrN material, which is the CrN precursor.

[0076] (2) Same as step (2) in Example 1;

[0077] (3) Same as step (3) in Example 1.

[0078] Application Examples

[0079] Preparation method of Pt / CrWN2 gas sensor:

[0080] 5 mg of Pt / CrWN2 prepared in Example 1 was dissolved in 460 μL of isopropanol solution and 40 μL of Nafion solution (5 wt%), respectively, and the solutions were thoroughly sonicated to obtain catalyst ink. The obtained Pt / CrWN2 catalyst ink was uniformly drop-coated onto two 1.5*1.5 cm sheets of carbon paper. After thorough drying, 20 μL of 5 wt% Nafion solution was uniformly drop-dropped onto the catalyst layer, and then dried again in an oven. The treated carbon paper was cut into circles with a diameter of 1 cm. Finally, the two layers of carbon paper and one layer of Nafion membrane were hot-pressed at 90 °C and 1.5 MPa to obtain a membrane electrode assembly (MEA). The MEA was then bonded together with a stainless steel electrode cap and a water storage tank to obtain the Pt / CrWN2 sensor (3:1 Pt / CrWN2 sensor) ready for operation.

[0081] The Pt / CrWN2 prepared in Example 2 was used to replace the Pt / CrWN2 prepared in Example 1. The other steps were the same as those for the preparation of the 3:1 Pt / CrWN2 sensor, and a 1:1 Pt / CrWN2 sensor was obtained.

[0082] The Pt / CrWN2 prepared in Example 3 was used to replace the Pt / CrWN2 prepared in Example 1. The other steps were the same as those for the preparation of the 3:1 Pt / CrWN2 sensor, resulting in a 1:3 Pt / CrWN2 sensor.

[0083] Method for fabricating Pt / C gas sensors:

[0084] 5 mg of Pt / C was dissolved in 460 μL of isopropanol solution and 40 μL of Nafion solution (5 wt%), and the mixture was thoroughly sonicated to obtain catalyst ink. The obtained Pt / C catalyst ink was uniformly drop-coated onto two 1.5*1.5 cm sheets of carbon paper. After thorough drying, 20 μL of 5 wt% Nafion solution was uniformly drop-dropped onto the catalyst layer, and then dried again in an oven. The treated carbon paper was cut into circles with a diameter of 1 cm. Finally, the two layers of carbon paper and one layer of Nafion membrane were hot-pressed at 90 °C and 1.5 MPa to obtain a membrane electrode assembly (MEA). The MEA was then bonded together with a stainless steel electrode cap and a water storage tank to obtain the Pt / C sensor ready for operation.

[0085] Performance testing

[0086] (1) Selectivity of Pt / CrWN2 gas sensor

[0087] Experimental method: The Pt / CrWN2 sensor and the Pt / C sensor were tested under different gas environments of 50 ppm, including target gas (H2S) and interfering gases (benzene, methanol (CH3OH), toluene, and acetone), and the response current values ​​were compared.

[0088] Data Analysis: Figure 3 The chart shows the statistical results of the selectivity test data for the Pt / CrWN2 gas sensor. The results indicate that the Pt / CrWN2 sensor has a much higher response to H2S than to other gases, demonstrating sensitive selectivity for H2S.

[0089] (2) Response recovery test of Pt / CrWN2 gas sensor

[0090] Experimental method: The Pt / CrWN2 sensor and the Pt / C sensor were tested in a 50ppm H2S environment. The response and recovery times of the sensors were measured during the adsorption and desorption processes, corresponding to 90% of ΔI.

[0091] Data Analysis: Figure 4 The graph shows the statistical data of the response-recovery test of the Pt / CrWN2 gas sensor. The results show that the Pt / CrWN2 sensor exhibits excellent response-recovery characteristics, with response time and recovery time of 3.6s and 3.5s for 50ppm H2S, respectively.

[0092] (3) Stability test of Pt / CrWN2 gas sensor

[0093] Experimental method: The stability of the Pt / CrWN2 sensor and the Pt / C sensor were tested for two weeks. During the two weeks, the Pt / CrWN2 sensor was used to test 50ppm H2S every day and the response current value was recorded.

[0094] Data Analysis: Figure 5 The graph shows the stability data of the Pt / CrWN2 gas sensor, indicating that the Pt / CrWN2 sensor exhibits excellent durability and stability. The Pt / CrWN2 sensor showed only minor fluctuations over 15 days.

[0095] (4) Comparison of tests on Pt / CrWN2 sensors with different ratios

[0096] Experimental method: The 3:1Pt / CrWN2 sensor, the 1:1Pt / CrWN2 sensor and the 1:3Pt / CrWN2 sensor were tested for 1-20ppm H2S respectively, and the optimal sensor ratio was determined.

[0097] Data Analysis: Figure 6 The test comparison charts for different Pt / CrWN2 sensors show that when the molar ratio of chromium source to tungsten source is 1:3, the synthesized CrWN2 has high purity and good performance.

[0098] The above description is only a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A Pt / CrWN2 gas-sensitive electrode material, characterized in that, The Pt / CrWN2 gas-sensitive electrode material is prepared by loading Pt onto the CrWN2 carrier material; the Pt / CrWN2 gas-sensitive electrode material exhibits a particle packing structure with a particle size of 15-25 nm, and the preparation method adopts the following steps: (1) Take chromium source, tungsten source and urea, add deionized water, sonicate and carry out hydrothermal reaction to obtain CrWN2 precursor; (2) The CrWN2 precursor obtained in step (1) is heated in an ammonia atmosphere to obtain the product CrWN2. (3) Take ethylene glycol, add CrWN2 and H2PtCl6 obtained in step (2), sonicate, and heat to react to obtain the Pt / CrWN2 gas-sensitive electrode material.

2. The Pt / CrWN2 gas-sensitive electrode material according to claim 1, characterized in that, In step (1), the chromium source is chromium chloride hexahydrate, and the tungsten source is sodium tungstate dihydrate.

3. The Pt / CrWN2 gas-sensitive electrode material according to claim 1, characterized in that, In step (1), the molar volume ratio of the chromium source, tungsten source, urea and deionized water is (1-4) mol: (1-4) mol: 4 mol: 50 mL; The hydrothermal reaction was carried out at a temperature of 140°C for 3 hours. The ultrasonic treatment time is 30 minutes; After the hydrothermal reaction is completed, filtration, washing, and drying are required. The drying temperature is 60℃ and the time is 8-12 hours.

4. The Pt / CrWN2 gas-sensitive electrode material according to claim 1, characterized in that, In step (2), the heating rate is 5℃ / min, the temperature is 800℃, and the time is 8h; After the heating process is complete, the mixture needs to be cooled to room temperature and then argon gas is introduced.

5. The Pt / CrWN2 gas-sensitive electrode material according to claim 1, characterized in that, In step (3), the concentration of the H2PtCl6 solution is 100 mg / L.

6. The Pt / CrWN2 gas-sensitive electrode material according to claim 1, characterized in that, In step (3), the mass-to-volume ratio of the CrWN2, H2PtCl6 solution and ethylene glycol is 5 mg: 34 μL: 5 mL; The ultrasonic treatment time is 30 minutes; The heating reaction was carried out at a temperature of 140°C for 3 hours. After the heating reaction is completed, cooling, washing, and drying are required.

7. The Pt / CrWN2 gas-sensitive electrode material according to claim 6, characterized in that, The drying temperature is 60℃ and the time is 8-12 hours.

8. The application of the Pt / CrWN2 gas-sensitive electrode material according to any one of claims 1-7, characterized in that, The Pt / CrWN2 gas-sensitive electrode material can be used to prepare gas sensors.

9. The application according to claim 8, characterized in that, The gas sensor can be used to detect H2S gas.

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