Preparation method of boron-nitrogen-doped graphene three-dimensional structure-supported platinum catalyst

Abstract

The present invention relates to the field of carbon-based catalyst preparation and discloses a method for preparing a three-dimensional structure of boron-nitrogen-doped graphene supported on platinum catalyst. The method comprises the following steps: uniformly mixing graphene sheets and boron nitride nanosheets, heating and reacting them under a nitrogen atmosphere, and then transferring the mixture to a muffle furnace for heating and reacting to obtain BCN after cooling; preparing BCN solution A; thoroughly mixing a graphene oxide (GO) suspension with solution A, ultrasonically treating the mixture to obtain a black, uniformly dispersed solution; adding a platinum salt, and mixing the mixture after ultrasonication to obtain solution C; placing solution C in a high-temperature and high-pressure reactor to react to obtain a hydrogel; washing the hydrogel, and vacuum freeze-drying the hydrogel to obtain a three-dimensional structure of boron-nitrogen-doped graphene supported on platinum catalyst. The preparation method of the present invention has a simple synthesis method and is easy to operate. The three-dimensional structure material is prepared by increasing defects in the carbon material to increase its active sites, thereby enhancing its electrocatalytic oxygen reduction performance, improving the utilization rate of precious metals, and realizing practical application of the material.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon-based catalyst preparation, and in particular to a method for preparing a three-dimensional structure of boron and nitrogen-doped graphene supported platinum catalyst. Background Art

[0002] Carbon-based catalysts are materials composed of carbon and its compounds. Due to their simple preparation methods and flexible and diverse structures, they are widely used in catalysis, energy conversion and other fields. Among carbon-based materials, graphene, with its high conductivity and large specific surface area, can provide a large number of active sites, promoting catalytic reactions. This gives it great potential for application in fuel cells, water electrolysis, and supercapacitors.

[0003] As a clean and efficient energy technology, hydrogen fuel cells hold significant potential and advantages in achieving global energy transition, addressing climate change, and promoting sustainable development. However, the oxygen reduction reaction (ORR), a key cathode reaction in fuel cells, involves complex multi-electron transfer and the breaking of oxygen molecular bonds, resulting in slow reaction kinetics and high energy barriers, making improving fuel cell performance a significant challenge. The development of efficient and stable ORR catalysts is crucial for improving fuel cell efficiency, thereby promoting the widespread application and sustainable development of clean energy.

[0004] However, graphene's catalytic activity is low and its stability is poor. The former is attributed to the smooth graphene basal surface and the susceptibility to corrosion or stacking of carbon supports, which significantly reduces the number of active sites. The latter is attributed to the potential for deactivation during long-term catalytic reactions, caused by factors such as the agglomeration of metal-loaded particles, which increases particle size and the exfoliation of graphene layers. Therefore, preparing three-dimensional structural materials, increasing carbon material defects to increase active sites, enhance their electrocatalytic oxygen reduction performance, and improve the utilization of precious metals are of great significance for the practical application of these materials. Summary of the Invention

[0005] The object of the present invention is to provide a method for preparing a three-dimensional structure of boron and nitrogen-doped graphene supported on a platinum catalyst, so as to solve the problems in the prior art.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A method for preparing a three-dimensional structure of boron and nitrogen-doped graphene supported on a platinum catalyst, the preparation method comprising the following steps:

[0008] S1. Graphene sheets and boron nitride nanosheets are uniformly mixed, heated in a nitrogen atmosphere for reaction, and then transferred to a muffle furnace for heating reaction after cooling to obtain BCN, and then BCN solution A is prepared;

[0009] S2. The graphene oxide (GO) suspension was fully mixed with solution A, and a black uniformly dispersed solution was obtained by ultrasonic treatment. Platinum salt was then added and mixed, and solution C was obtained after ultrasonic treatment.

[0010] S3. Place solution C in a high-temperature and high-pressure reactor to react and obtain a hydrogel. After washing the hydrogel, vacuum freeze-drying is performed to obtain a three-dimensional structure of boron-nitrogen-doped graphene loaded with a platinum catalyst.

[0011] Furthermore, 100 mg of graphene sheets and 100 mg of boron nitride nanosheets in S1 were uniformly mixed, heated to 800-900° C. in a nitrogen atmosphere, reacted for 2 h, and then cooled to room temperature and transferred to a muffle furnace and heated to 400-500° C. and reacted for 6 h to obtain BCN.

[0012] Furthermore, the BCN solution A in S1 is prepared by proportioning BCN and a mixed liquid, which are fully mixed and dispersed. The concentration of the obtained BCN solution A is 2 mg / ml, wherein the mixed liquid is prepared by ultrapure water and ethylene glycol in a volume ratio of 1:1.

[0013] Furthermore, in S2, 5 ml of graphene oxide GO suspension was fully mixed with 5 ml of solution A, and ultrasonicated for 1 h to obtain a black uniformly dispersed solution, and then platinum salt was added and mixed, and ultrasonicated for 30 min to obtain solution C;

[0014] The concentration of graphene oxide (GO) suspension was the same as that of solution A, both of which were 2 mg / ml.

[0015] Furthermore, the amount of platinum salt added to S2 is 13.2-14.1 mg.

[0016] Furthermore, the platinum salt in S2 is one of chloroplatinic acid or potassium chloroplatinate.

[0017] Furthermore, the specific operation in S3 is: transferring solution C together with its glass device to the lined cup, and placing it in a high-temperature and high-pressure reactor, heating and keeping it at 120-140°C for 12-16 hours, washing the hydrogel with deionized water for 4-5 days, and then placing it in a freeze dryer for vacuum freeze drying.

[0018] Furthermore, after the platinum salt in S3 is hydrothermally reduced to platinum metal and vacuum freeze-dried, the platinum nanoparticles are uniformly dispersed in the three-dimensional carbon skeleton of the platinum catalyst.

[0019] Beneficial effects of the present invention:

[0020] 1. The preparation method of the present invention uses a solvothermal strategy to construct a three-dimensional structure of boron- and nitrogen-doped graphene loaded with platinum catalyst material. The resulting three-dimensional porous defect structure can increase the electrochemical active area and effectively inhibit the agglomeration of nanoparticles. In addition, its unique pore structure facilitates the flow of external electrolyte into and out of the internal structure of the material, ensuring that the reaction medium can fully contact the active sites, thereby improving its electrocatalytic activity.

[0021] 2. The preparation method of the present invention is simple and easy to operate. It also utilizes the synergistic effect of low-electronegativity B and high-electronegativity N to enhance the electron migration ability of the carbon skeleton, regulate the electronic structure of graphene, and strengthen the coupling between the platinum nanoparticles and the support. This coupling not only reduces the size of the platinum particles but also improves their uniform distribution, accelerates the cracking of the *OOH intermediate in the reaction process, and improves the performance of the four-electron oxygen reduction reaction.

[0022] 3. The preparation method of the present invention prepares three-dimensional structural materials, increases the defects of carbon materials to increase their active sites, enhances their electrocatalytic oxygen reduction performance, and improves the utilization rate of precious metals, which is of great significance for realizing the practical application of materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The present invention will be further described below with reference to the accompanying drawings.

[0024] Figure 1 This is an SEM image of the three-dimensional structure of boron and nitrogen-doped graphene loaded with platinum catalyst of the present invention;

[0025] Figure 2 This is an SEM image of the three-dimensional structure of boron and nitrogen-doped graphene loaded with platinum catalyst of the present invention;

[0026] Figure 3 This is a TEM image of the three-dimensional structure of boron and nitrogen-doped graphene loaded with platinum catalyst of the present invention;

[0027] Figure 4 This is a TEM image of the three-dimensional structure of boron and nitrogen-doped graphene loaded with platinum catalyst of the present invention;

[0028] Figure 5 Mapping diagram of the three-dimensional structure of boron and nitrogen-doped graphene loaded with platinum catalyst of the present invention;

[0029] Figure 6 This is a performance diagram of the Pt / GO-BCN of the present invention. DETAILED DESCRIPTION

[0030] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0031] A method for preparing a three-dimensional structure of boron and nitrogen-doped graphene supported on a platinum catalyst, the preparation method comprising the following steps:

[0032] S1. Weigh 100 mg of graphene sheets and 100 mg of boron nitride nanosheets and mix them evenly. Heat them to 800-900°C under a nitrogen atmosphere and react for 2 hours. After cooling to room temperature, transfer them to a muffle furnace and heat them to 400-500°C and react for 6 hours to obtain BCN. Prepare a mixture of ultrapure water and ethylene glycol in a 1:1 volume ratio, then add BCN to the mixture, configure according to the proportion and mix thoroughly. After ultrasonic treatment for 1 hour, a uniformly dispersed 2 mg / ml BCN solution A can be obtained.

[0033] S2. 5 ml of graphene oxide (GO) suspension (2 mg / ml) was thoroughly mixed with 5 ml of solution A (2 mg / ml). After ultrasonic treatment for 1 h, a black uniformly dispersed solution was obtained. 13.2-14.1 mg of platinum salt was then added and mixed. After ultrasonic treatment for 30 min, solution C was obtained.

[0034] S3. Transfer solution C together with its glass device to an inner-lined cup and place it in a high-temperature and high-pressure reactor, heat and keep it at 120-140°C for 12-16 hours, wash the resulting hydrogel with deionized water for 4-5 days, and place it in a freeze dryer for vacuum freeze drying to obtain a three-dimensional structure of boron and nitrogen-doped graphene loaded with platinum catalyst.

[0035] In the above step S2, the platinum salt used can be chloroplatinic acid or potassium chloroplatinate. In the subsequent step S3, the platinum salt is hydrothermally reduced to platinum metal and vacuum freeze-dried, so that the platinum nanoparticles can be evenly dispersed in the three-dimensional carbon skeleton.

[0036] Example 1

[0037] A method for preparing a three-dimensional structure of boron and nitrogen-doped graphene supported on a platinum catalyst, the preparation method comprising the following steps:

[0038] S1. Weigh 100 mg of graphene sheets and 100 mg of boron nitride nanosheets and mix them evenly. Heat them to 800°C under a nitrogen atmosphere and react for 2 hours. After cooling to room temperature, transfer them to a muffle furnace and heat them to 400°C for 6 hours to obtain BCN. Prepare a mixture of ultrapure water and ethylene glycol in a 1:1 volume ratio. Add BCN to the mixture, configure according to the proportion and mix thoroughly. After ultrasonic treatment for 1 hour, a uniformly dispersed 2 mg / ml BCN solution A can be obtained.

[0039] S2. 5 ml of graphene oxide (GO) suspension (2 mg / ml) was thoroughly mixed with 5 ml of solution A (2 mg / ml). After ultrasonic treatment for 1 h, a black uniformly dispersed solution was obtained. 13.2 mg of potassium chloroplatinate was added and mixed. After ultrasonic treatment for 30 min, solution C was obtained.

[0040] S3. Transfer solution C together with its glass device to an inner-lined cup and place it in a high-temperature and high-pressure reactor, heat it at 120°C for 12 hours, wash the resulting hydrogel with deionized water for 4 days, and place it in a freeze dryer for vacuum freeze drying to obtain a three-dimensional structure of boron and nitrogen-doped graphene loaded with platinum catalyst.

[0041] Example 2

[0042] A method for preparing a three-dimensional structure of boron and nitrogen-doped graphene supported on a platinum catalyst, the preparation method comprising the following steps:

[0043] S1. Weigh 100 mg of graphene sheets and 100 mg of boron nitride nanosheets and mix them evenly. Heat them to 850°C under a nitrogen atmosphere and react for 2 hours. After cooling to room temperature, transfer them to a muffle furnace and heat them to 450°C for 6 hours to obtain BCN. Prepare a mixture of ultrapure water and ethylene glycol in a 1:1 volume ratio, then add BCN to the mixture, configure them according to the proportion and mix them thoroughly. After ultrasonic treatment for 1 hour, a uniformly dispersed 2 mg / ml BCN solution A can be obtained.

[0044] S2. 5 ml of graphene oxide (GO) suspension (2 mg / ml) was thoroughly mixed with 5 ml of solution A (2 mg / ml). After ultrasonic treatment for 1 h, a black uniformly dispersed solution was obtained. 13.7 mg of chloroplatinic acid was then added and mixed. After ultrasonic treatment for 30 min, solution C was obtained.

[0045] S3. Transfer solution C together with its glass device to an inner-lined cup and place it in a high-temperature and high-pressure reactor, heating and keeping it at 130°C for 14 hours. After washing the obtained hydrogel with deionized water for 4.5 days, place it in a freeze dryer for vacuum freeze drying to obtain a three-dimensional structure of boron and nitrogen-doped graphene loaded with platinum catalyst.

[0046] Example 3

[0047] A method for preparing a three-dimensional structure of boron and nitrogen-doped graphene supported on a platinum catalyst, the preparation method comprising the following steps:

[0048] S1. Weigh 100 mg of graphene sheets and 100 mg of boron nitride nanosheets and mix them evenly. Heat them to 900°C under a nitrogen atmosphere and react for 2 hours. After cooling to room temperature, transfer them to a muffle furnace and heat them to 500°C for 6 hours to obtain BCN. Prepare a mixture of ultrapure water and ethylene glycol in a 1:1 volume ratio, then add BCN to the mixture, configure them according to the proportion and mix them thoroughly. After ultrasonic treatment for 1 hour, a uniformly dispersed 2 mg / ml BCN solution A can be obtained.

[0049] S2. 5 ml of graphene oxide (GO) suspension (2 mg / ml) was thoroughly mixed with 5 ml of solution A (2 mg / ml). After ultrasonic treatment for 1 h, a black uniformly dispersed solution was obtained. 14.1 mg of potassium chloroplatinate was added and mixed. After ultrasonic treatment for 30 min, solution C was obtained.

[0050] S3. Transfer solution C together with its glass device to an inner-lined cup and place it in a high-temperature and high-pressure reactor, heat it at 140°C for 16 hours, wash the resulting hydrogel with deionized water for 5 days, and place it in a freeze dryer for vacuum freeze drying to obtain a three-dimensional structure of boron and nitrogen-doped graphene loaded with platinum catalyst.

[0051] See also Figure 1-6 , the morphology characterization and ORR performance test of Pt / GO-BCN were carried out, and the relevant data are as follows:

[0052] The three-dimensional structure of boron and nitrogen-doped graphene loaded with platinum catalyst material prepared by a simple solvent thermal strategy undergoes a hydrothermal process to form a three-dimensional columnar structure, avoiding the stacking of two-dimensional carbon nanostructures.

[0053] like Figure 1-5 As shown, the SEM, TEM and mapping images of the three-dimensional structure of boron and nitrogen-doped graphene loaded with platinum catalysts indicate that it forms a porous defect structure, the electrochemical active area is increased, and more catalytic active sites can be provided. Its unique pore structure also makes it easier for external electrolytes to enter and exit the internal structure of the material.

[0054] like Figure 6 As shown in the figure, the electrochemical performance diagram of the three-dimensional structure of boron and nitrogen-doped graphene loaded with platinum catalyst, the four-electron oxygen reduction performance of the sample was tested using a rotating disk electrode, and a high half-wave potential of 0.9V was obtained, indicating that its reaction energy barrier was reduced.

[0055] Compared with related technologies, the preparation method of the three-dimensional structure of boron and nitrogen-doped graphene supported platinum catalyst provided by the present invention has the following beneficial effects:

[0056] 1. The present invention provides a method for preparing a three-dimensional structure of boron and nitrogen-doped graphene loaded with platinum catalyst. A three-dimensional structure of boron and nitrogen-doped graphene loaded with platinum catalyst material is constructed through a solvent thermal strategy. The formed three-dimensional porous defect structure can increase the electrochemical active area and effectively inhibit the agglomeration of nanoparticles. Moreover, its unique pore structure can make it easier for the external electrolyte to enter and exit the internal structure of the material, ensuring that the reaction medium can fully contact the active sites, thereby improving its electrocatalytic activity.

[0057] Second, the present invention provides a method for preparing a three-dimensional boron- and nitrogen-doped graphene-supported platinum catalyst. This method is not only simple and easy to operate, but also utilizes the synergistic effect of low-electronegativity B and high-electronegativity N to enhance the electron transfer capability of the carbon framework, regulate the electronic structure of the graphene, and thus strengthen the coupling between the platinum nanoparticles and the support. This coupling not only reduces the size of the platinum particles but also improves their uniform distribution, accelerating the cracking of the *OOH intermediate during the reaction and improving the performance of the four-electron oxygen reduction reaction.

[0058] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention, and such changes and modifications fall within the scope of the invention as claimed.

Claims

1. A method for preparing a three-dimensional structure of boron and nitrogen-doped graphene supported on a platinum catalyst, characterized in that: The preparation method comprises the following steps: S1. Graphene sheets and boron nitride nanosheets are uniformly mixed, heated under a nitrogen atmosphere for reaction, and then transferred to a muffle furnace for heating reaction after cooling to obtain BCN, and then BCN solution A is prepared; S2. The graphene oxide (GO) suspension was fully mixed with solution A, and a black uniformly dispersed solution was obtained by ultrasonic treatment. Platinum salt was then added and mixed, and solution C was obtained after ultrasonic treatment. S3, placing solution C in a high-temperature and high-pressure reactor to react to obtain a hydrogel, washing the hydrogel, and then performing vacuum freeze-drying to obtain a three-dimensional structure of boron-nitrogen-doped graphene loaded with platinum catalyst; The BCN solution A in S1 is prepared by mixing BCN and a mixed solution in a certain proportion, and then fully mixing and dispersing the mixture. The concentration of the obtained BCN solution A is 2 mg / ml, wherein the mixed solution is prepared by mixing ultrapure water and ethylene glycol in a ratio of 1:1 by volume; In S2, 5 ml of graphene oxide (GO) suspension was thoroughly mixed with 5 ml of solution A, and ultrasonicated for 1 hour to obtain a black uniformly dispersed solution, and then platinum salt was added and mixed, and ultrasonicated for 30 minutes to obtain solution C; The concentration of graphene oxide (GO) suspension was the same as that of solution A, both of which were 2 mg / ml.

2. The method for preparing a three-dimensional structure of boron-nitrogen-doped graphene supported platinum catalyst according to claim 1, characterized in that: 100 mg of graphene sheets and 100 mg of boron nitride nanosheets in S1 were uniformly mixed, heated to 800-900° C. in a nitrogen atmosphere, reacted for 2 h, and then cooled to room temperature and transferred to a muffle furnace, heated to 400-500° C., and reacted for 6 h to obtain BCN.

3. The method for preparing a three-dimensional structure of boron-nitrogen-doped graphene supported platinum catalyst according to claim 1, characterized in that: The amount of platinum salt added to S2 is 13.2-14.1 mg.

4. The method for preparing a three-dimensional structure of boron-nitrogen-doped graphene supported platinum catalyst according to claim 3, characterized in that: The platinum salt in S2 is one of chloroplatinic acid or potassium chloroplatinate.

5. The method for preparing a three-dimensional structure of boron-nitrogen-doped graphene supported platinum catalyst according to claim 1, characterized in that: The specific operation in S3 is as follows: transferring solution C together with its glass device to the lined cup, and placing it in a high-temperature and high-pressure reactor, heating and keeping it at 120-140°C for 12-16 hours, washing the hydrogel with deionized water for 4-5 days, and then placing it in a freeze dryer for vacuum freeze drying.

6. The method for preparing a three-dimensional structure of boron-nitrogen-doped graphene supported platinum catalyst according to claim 5, characterized in that: After the platinum salt in S3 is hydrothermally reduced to platinum metal and vacuum freeze-dried, the platinum nanoparticles are evenly dispersed in the three-dimensional carbon skeleton of the platinum catalyst.

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