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

Abstract

The invention relates to the field of preparation of carbon-based catalysts, and discloses a preparation method of a boron-nitrogen-doped graphene three-dimensional structure platinum-loaded catalyst, which comprises the following steps: uniformly mixing graphene sheets and boron nitride nanosheets, heating and reacting in a nitrogen atmosphere, cooling, transferring to a muffle furnace, heating and reacting to obtain BCN, and preparing a BCN solution A; fully mixing a graphene oxide GO suspension with the solution A, performing ultrasonic treatment to obtain a black uniformly dispersed solution, adding platinum salt, mixing, and performing ultrasonic treatment to obtain a solution C; placing the solution C in a high-temperature and high-pressure reaction kettle for reaction to obtain hydrogel, cleaning the hydrogel, and performing vacuum freeze drying to obtain the boron-nitrogen-doped graphene three-dimensional structure loaded platinum catalyst. The preparation method and the synthesis method are simple and easy to operate, the three-dimensional structure material is prepared, the defects of the carbon material are increased, the active sites of the carbon material are increased, the electro-catalytic oxygen reduction performance of the carbon material is enhanced, the utilization rate of precious metal is increased, and practical application of the material is achieved.

Description

Technical Field

[0001] The 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-nitrogen-doped graphene supported platinum catalyst. Background Art

[0002] Carbon-based catalysts are materials composed of carbon and its compounds. They are widely used in catalysis, energy conversion and other fields due to their simple preparation methods and flexible and diverse structures. In the family of carbon-based materials, graphene has high conductivity and high specific surface area, which can provide a large number of active sites and promote catalytic reactions, making it show great application potential in fuel cells, water electrolysis and supercapacitors.

[0003] As a clean and efficient energy technology, hydrogen fuel cells have important potential and advantages in achieving global energy structure transformation, addressing climate change and promoting sustainable development. The oxygen reduction reaction (ORR), as a key cathode reaction in fuel cells, involves complex multi-electron transfer processes and the breaking of oxygen molecular bonds, and has slow reaction kinetics and high energy barriers, which makes it a huge challenge to improve the performance of fuel cells. The development of efficient and stable ORR catalysts is of great significance to improving the efficiency of fuel cells, thereby promoting the widespread application and sustainable development of clean energy.

[0004] However, graphene has low catalytic activity and poor stability. The former is attributed to the smooth graphene basal surface, easy corrosion of carbon carriers or stacking, which leads to a large reduction in active sites. The latter is attributed to the deactivation phenomenon that may occur during long-term catalytic reactions, which is caused by the agglomeration of metal-loaded particles, resulting in increased particle size and peeling of graphene layers. Therefore, preparing three-dimensional structural materials, increasing the defects of carbon materials to increase their active sites, enhancing their electrocatalytic oxygen reduction performance, and improving the utilization rate of precious metals are of great significance to the practical application of 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-nitrogen-doped graphene loaded with platinum catalyst 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-nitrogen-doped graphene supported platinum catalyst, the preparation method comprising the following steps:

[0008] S1, taking graphene sheets and boron nitride nanosheets and mixing them evenly, heating them in a nitrogen atmosphere for reaction, and then transferring them to a muffle furnace for heating reaction after cooling to obtain BCN, and then preparing BCN solution A;

[0009] S2, the graphene oxide GO suspension is fully mixed with solution A, and a black uniformly dispersed solution is obtained by ultrasonic treatment, and then platinum salt is added and mixed, and solution C is 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 and nitrogen-doped graphene loaded with a platinum catalyst.

[0011] Furthermore, 100 mg of graphene sheets and 100 mg of boron nitride nanosheets in S1 are uniformly mixed, heated to 800-900° C. in a nitrogen atmosphere, reacted for 2 hours, cooled to room temperature, transferred to a muffle furnace, heated to 400-500° C., and reacted for 6 hours 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, and 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 a black uniformly dispersed solution was obtained after ultrasonic treatment for 1 hour, and then platinum salt was added and mixed, and solution C was obtained after ultrasonic treatment for 30 minutes;

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

[0015] Furthermore, the amount of platinum salt added in 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 warm at 120-140°C for 12-16h, washing the hydrogel with deionized water for 4-5d, 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 evenly 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 constructs a three-dimensional structure of boron and nitrogen-doped graphene loaded with platinum catalyst material through a solvothermal 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 site, thereby improving its electrocatalytic activity;

[0021] 2. The preparation method of the present invention is simple in synthesis 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 enhance the coupling effect between platinum nanoparticles and the carrier. This coupling effect not only reduces the size of platinum particles, but also improves their uniform distribution, accelerates the cracking of the *OOH intermediate in the reaction process, and improves its four-electron oxygen reduction performance;

[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 in conjunction with the accompanying drawings.

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

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

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

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

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 creative work are within the scope of protection of the present invention.

[0031] A method for preparing a three-dimensional structure of boron-nitrogen-doped graphene supported 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 in a nitrogen atmosphere, react for 2 hours, and then transfer them to a muffle furnace and heat them to 400-500°C after cooling to room temperature. React for 6 hours to obtain BCN. Prepare a mixed solution with ultrapure water and ethylene glycol in a volume ratio of 1:1, then add BCN into the mixed solution, 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.

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

[0034] S3. Transfer solution C together with its glass device to the lined cup, and put it into a high temperature and high pressure reactor, heat it at 120-140°C for 12-16 hours, wash the obtained hydrogel with deionized water for 4-5 days, and then put it into 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-nitrogen-doped graphene supported 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 to 800°C in a nitrogen atmosphere, react for 2 hours, and then transfer to a muffle furnace and heat to 400°C after cooling to room temperature. React for 6 hours to obtain BCN. Prepare a mixed solution with ultrapure water and ethylene glycol in a volume ratio of 1:1, then add BCN into the mixed solution, 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 fully mixed with 5 ml of solution A (2 mg / ml), and a black uniformly dispersed solution was obtained after ultrasonic treatment for 1 h, and 13.2 mg of potassium chloroplatinate was added and mixed, and solution C was obtained after ultrasonic treatment for 30 min;

[0040] S3. Transfer solution C together with its glass device to the lined cup, and put it into a high temperature and high pressure reactor, heat it at 120°C for 12 hours, wash the obtained hydrogel with deionized water for 4 days, and then put it into 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-nitrogen-doped graphene supported 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 to 850°C in a nitrogen atmosphere, react for 2 hours, and then transfer to a muffle furnace and heat to 450°C after cooling to room temperature. React for 6 hours to obtain BCN. Prepare a mixed solution with ultrapure water and ethylene glycol in a volume ratio of 1:1, then add BCN into the mixed solution, 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.

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

[0045] S3. Transfer solution C together with its glass device to the lined cup, and put it into a high temperature and high pressure reactor, heat it at 130°C for 14 hours, wash the obtained hydrogel with deionized water for 4.5 days, and then put it into 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-nitrogen-doped graphene supported 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 to 900°C in a nitrogen atmosphere, react for 2 hours, and then transfer to a muffle furnace and heat to 500°C after cooling to room temperature. React for 6 hours to obtain BCN. Prepare a mixed solution with ultrapure water and ethylene glycol in a volume ratio of 1:1, then add BCN into the mixed solution, 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.

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

[0050] S3. Transfer solution C together with its glass device to the lined cup, and put it into a high temperature and high pressure reactor, heat it at 140°C for 16 hours, wash the obtained hydrogel with deionized water for 5 days, and then put it into 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 solvothermal 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, 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 the related art, 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] 2. The present invention provides a method for preparing a three-dimensional structure of boron and nitrogen-doped graphene supported platinum catalyst. Not only is the synthesis method simple and easy to operate, but also the synergistic effect of low electronegativity B and high electronegativity N is used to enhance the electron migration ability of the carbon skeleton and regulate the electronic structure of graphene, thereby enhancing the coupling effect between platinum nanoparticles and the carrier. This coupling effect 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 its four-electron oxygen reduction performance.

[0058] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. A method for preparing a three-dimensional structure of boron-nitrogen-doped graphene supported on a platinum catalyst, characterized in that: The preparation method comprises the following steps: S1, taking graphene sheets and boron nitride nanosheets and mixing them evenly, heating them in a nitrogen atmosphere for reaction, and then transferring them to a muffle furnace for heating reaction after cooling to obtain BCN, and then preparing BCN solution A; S2, the graphene oxide GO suspension is fully mixed with solution A, and a black uniformly dispersed solution is obtained by ultrasonic treatment, and then platinum salt is added and mixed, and solution C is obtained after ultrasonic treatment; 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 and nitrogen-doped graphene loaded with a platinum catalyst.

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 are uniformly mixed, heated to 800-900° C. in a nitrogen atmosphere, reacted for 2 hours, cooled to room temperature, transferred to a muffle furnace, heated to 400-500° C., reacted for 6 hours, and obtained 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 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.

4. The method for preparing a three-dimensional structure of boron-nitrogen-doped graphene supported platinum catalyst according to claim 3, characterized in that: In S2, 5 ml of graphene oxide GO suspension is fully mixed with 5 ml of solution A, and after ultrasonic treatment for 1 hour, a black uniformly dispersed solution is obtained, and then platinum salt is added and mixed, and solution C is obtained after ultrasonic treatment for 30 minutes; The concentration of graphene oxide GO suspension is the same as that of solution A, both of which are 2 mg / ml.

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 amount of platinum salt added in S2 is 13.2-14.1 mg.

6. The method for preparing a three-dimensional structure of boron-nitrogen-doped graphene supported platinum catalyst according to claim 5, characterized in that: The platinum salt in S2 is one of chloroplatinic acid or potassium chloroplatinate.

7. 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: transferring solution C together with its glass device to the lined cup, and placing it in a high temperature and high pressure reactor, heating 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.

8. The method for preparing a three-dimensional structure of boron-nitrogen-doped graphene supported platinum catalyst according to claim 7, 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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