A quasi-one-dimensional / two-dimensional low-platinum-loaded catalyst and its preparation method

Abstract

The present invention belongs to the field of new energy technology and specifically provides a quasi-one-dimensional / two-dimensional low-platinum-loaded catalyst and a preparation method thereof, wherein the catalyst comprises: quasi-two-dimensional graphene formed by partial chemical exfoliation and chemical reduction of a quasi-one-dimensional carbon nanoscroll; the quasi-two-dimensional graphene and the remaining quasi-one-dimensional carbon nanoscroll portion connected to the quasi-two-dimensional graphene are used as structural basic units, and are bonded in three dimensions by van der Waals forces to form a nanoporous structure; and the surface of the nanoporous structure is loaded with platinum. By constructing an effective nanoporous conductive carbon-based network, it provides rapid electron transport and oxygen molecule diffusion channels for the oxygen reduction reaction at the cathode of a hydrogen fuel cell. At the same time, the network structure can highly stably and densely load small-sized platinum atoms and nanoparticles, providing highly stable and high-density reaction sites for the catalytic reaction, thereby achieving stable output of large current from the catalyst cathode membrane.

Description

Technical Field

[0001] The present invention relates to the field of new energy technology, and more specifically, to a quasi-one-dimensional / two-dimensional low-platinum-loaded catalyst and a preparation method thereof. Background Art

[0002] Hydrogen fuel cells are environmentally friendly, low-pollution energy devices. They operate by feeding hydrogen into the anode and oxygen into the cathode. Hydrogen is oxidized in the anode catalyst layer into hydrogen ions and electrons. The hydrogen ions travel through the proton exchange membrane to the cathode, creating a voltage difference. The electrons travel through an external circuit to the cathode, generating a current that drives a motor in the external circuit. Hydrogen ions, electrons, and oxygen react in the cathode catalyst layer to produce water, which is then discharged. Proton exchange membrane fuel cells (PEMFCs) have attracted widespread attention due to their unique advantages, including high power density, high efficiency, zero emissions, fast startup, and high energy conversion rates. However, the development of PEMFCs is severely hampered by the sluggish oxygen reduction reaction (ORR) at the cathode, poor catalyst activity and durability, and the high cost and scarcity of platinum metal. Overcoming these issues will make the commercialization of catalysts a reality. In recent years, extensive research has been conducted to improve fuel cell conversion efficiency. Platinum-based catalysts, currently the most efficient catalytic material for fuel cells, are crucial for their performance. Their performance depends on the size of the platinum particles and their distribution on the support. By selecting an appropriate support material, the surface dispersion and stability of platinum catalysts can be improved, fully utilizing the platinum metal and reducing platinum usage. Currently, commercial ORR catalysts primarily consist of Pt / C composite catalysts, made by loading platinum particles onto a carbon support. Therefore, finding a carbon support material with high catalytic activity and stability is crucial for ORR catalyst research.

[0003] Graphene, with its high conductivity, high specific surface area, and excellent electrochemical stability, is a novel carbon support material for ORR catalysts. However, the stacking of graphene during the preparation process reduces the number of platinum particle deposition sites on the support surface, reducing the utilization rate of the platinum particles. Furthermore, during the oxygen reduction process, polymerization can cover some active sites, hindering oxygen diffusion, and causing some platinum particles to agglomerate after detachment.

[0004] For example, patent CN107335451A combines graphene and molybdenum disulfide to create a three-dimensional porous structure. This material uses molybdenum disulfide to bond between graphene layers, forming a three-dimensional network structure that prevents graphene from agglomerating and stacking. However, the presence of microporous structures within the material can trap Pt particles, reducing Pt utilization and hindering exposure of the active surface of the Pt particles.

[0005] Patent CN114725412A co-sinters nitrogen-doped graphene oxide with chloroplatinic acid. Due to the abundant active sites on nitrogen-doped graphene oxide and the strong chemical bonds formed by nitrogen atoms with platinum at high temperatures, the resulting composite material is extremely uniformly loaded with platinum nanoparticles at a high density on the graphene plane. However, graphene is a two-dimensional planar structure, and the microstructure of its macroscopic powder is a stack of graphene. This results in a large number of platinum nanoparticles being covered by graphene, making it difficult to effectively expose the platinum atoms. This structure is also detrimental to the diffusion of oxygen molecules, affecting the current density per unit area of the cathode. In contrast, carbon nanotubes (CNTs) can effectively achieve mesoporous nanonetworks for efficient gas diffusion. CNTs are a unique one-dimensional structural material formed by the curling of hexagonal graphene formed by a large number of carbon atoms bonded together. CNTs have a high specific surface area, providing more deposition sites for platinum nanoparticles. Compared with traditional carbon black, they have better electrical conductivity and lower impurities. At the same time, carbon nanotubes can improve the interaction between metal and carrier, so that the Pt-based catalyst supported by carbon nanotubes shows good activity and stability during the electrochemical reaction.

[0006] Patent CN115084547A, for example, combines the advantages of the aforementioned technologies, utilizing the porous nanonetwork of carbon nanotubes, alloyed anchoring technology, and abundant surface sites of activated carbon nanotubes. This synergistic effect enhances the exposure of platinum atoms and strengthens the anchoring of platinum nanoparticles, aiming to provide the catalyst composite with improved oxygen diffusion characteristics, higher catalytic activity and stability, and thus enhance the overall performance of the composite catalyst material. However, performance comparisons of the examples in the patent show that catalyst performance still significantly degrades after long-term cycling testing, indicating that directly loading platinum nanoparticles on the carbon nanotube surface cannot effectively stabilize the catalyst structure. Summary of the Invention

[0007] The present invention addresses the technical problem in the prior art of how to effectively construct an effective nanoporous conductive carbon-based network.

[0008] The present invention provides a quasi-one-dimensional / two-dimensional low-platinum-loaded catalyst, comprising:

[0009] Quasi-two-dimensional graphene formed by partial chemical exfoliation and chemical reduction of quasi-one-dimensional carbon nanoscrolls;

[0010] The quasi-two-dimensional graphene and the remaining quasi-one-dimensional carbon nanoscroll portion connected to the quasi-two-dimensional graphene are used as structural basic units and combined through van der Waals forces in three-dimensional space to form a nanoporous structure; and the surface of the nanoporous structure is loaded with platinum.

[0011] Preferably, in the nanoporous structure, the quasi-one-dimensional carbon nanoscroll still has a diameter of 20 nm to 200 nm after partial chemical exfoliation.

[0012] Preferably, in the nanoporous structure, the quasi-two-dimensional graphene is obtained by peeling off from the surface of the quasi-one-dimensional carbon nanoscroll and then chemically reducing it, but the graphene oxide obtained by chemical peeling and the quasi-two-dimensional graphene obtained by chemical reduction are always tightly connected to the quasi-one-dimensional carbon nanoscroll through conjugated chemical bonds.

[0013] Preferably, the platinum is one or more of a single atom, a diatomic, a polyatomic or a nanoparticle, and the size of the platinum dispersed on the surface of the carbon material with a nanoporous structure is not greater than 5 nanometers.

[0014] The present invention also provides a method for preparing a quasi-one-dimensional / two-dimensional low-platinum-loaded catalyst, comprising the following steps:

[0015] S1, placing the quasi-one-dimensional carbon nanoscroll into a potassium permanganate concentrated sulfuric acid solution and stirring to react to obtain a mixed solution;

[0016] S2, pouring the mixed solution into ice cubes to cool and dilute it, adding deionized water after the ice cubes melt, and then adding hydrogen peroxide to terminate the chemical reaction to obtain a transition solution;

[0017] S3, adding hydrochloric acid and then deionized water to the transition liquid, stirring, and standing, and then filtering and washing the collected solid with deionized water to obtain a quasi-one-dimensional carbon nanoscroll with partially exfoliated oxidized quasi-two-dimensional graphene.

[0018] S4, dispersing the quasi-one-dimensional carbon nanoscroll in deionized water, adding chloroplatinic acid or potassium chloroplatinate solution, stirring evenly and keeping warm, adding hydrazine hydrate or sodium borohydride or glucose for reduction treatment, continuing stirring, and then filtering and drying to obtain a composite powder.

[0019] Preferably, in S1:

[0020] The diameter of the quasi-one-dimensional carbon nanoscroll raw materials ranges from 8 nanometers to 300 nanometers;

[0021] The mass ratio of potassium permanganate to quasi-one-dimensional carbon nanoscroll is in the range of 5 to 10;

[0022] The reaction temperature is between 0°C and 40°C;

[0023] The reaction stirring time is between 30 minutes and 4 hours.

[0024] Preferably, the volume of the ice cubes in S2 is 1.5 to 3 times the volume of the mixed liquid in S1.

[0025] Preferably, the molar amount of hydrochloric acid added in S3 is 2 to 6 times the molar amount of potassium permanganate.

[0026] Preferably, in S4:

[0027] The insulation range is 50℃ to 96℃;

[0028] When using hydrazine hydrate as a reducing agent, the temperature is controlled at 70°C to 80°C;

[0029] When sodium borohydride is used as the reducing agent, the temperature is controlled between 60°C and 85°C;

[0030] When glucose is used as the reducing agent, the temperature is controlled at 85°C to 95°C.

[0031] The present invention also provides a catalyst material for a hydrogen fuel cell negative electrode, wherein the hydrogen fuel cell negative electrode catalyst material comprises a composite powder prepared by a quasi-one-dimensional / two-dimensional low-platinum-loaded catalyst preparation method.

[0032] Beneficial effects: The present invention provides a quasi-one-dimensional / two-dimensional low-platinum-loaded catalyst and a preparation method thereof, wherein the catalyst comprises: quasi-two-dimensional graphene formed by partial chemical exfoliation and chemical reduction of a quasi-one-dimensional carbon nanoscroll; the quasi-two-dimensional graphene and the remaining quasi-one-dimensional carbon nanoscroll portion connected to the quasi-two-dimensional graphene are used as basic structural units, and are combined in three-dimensional space by van der Waals forces to form a nanoporous structure; and the surface of the nanoporous structure is loaded with platinum. By constructing an effective nanoporous conductive carbon-based network, it provides fast electron transport and oxygen molecule diffusion channels for the oxygen reduction reaction at the cathode of a hydrogen fuel cell. At the same time, the network structure can highly stably and densely load small-sized platinum atoms and nanoparticles, providing highly stable and high-density reaction sites for the catalytic reaction, and achieving a stable output of large current from the catalyst cathode membrane.

[0033] The composite material consists of a sheet of graphene, obtained by oxidative exfoliation and chemical reduction of carbon nanotubes, connected to a twisted and entangled quasi-one-dimensional carbon nanoscroll. The graphene and quasi-one-dimensional carbon nanoscrolls form a quasi-one- / two-dimensional nanoporous structure that improves graphene stacking, enhances the anchoring of platinum particles on the carrier material, and also serves as a mass transfer agent. The sheet of graphene in this structure contains numerous defects and functional groups, making it more effective at dispersing and loading platinum atoms and nanoparticles than quasi-one-dimensional carbon nanoscrolls or carbon nanotubes. It also enhances the material's hydrophilicity, helping the catalyst better manage water. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 A flow chart of a method for preparing a quasi-one / two-dimensional low-platinum-loaded catalyst provided by the present invention;

[0035] Figure 2 This is an SEM image of the quasi-two-dimensional graphene-connected carbon nanotube-supported platinum catalyst obtained in Example 1 provided by the present invention;

[0036] Figure 3This is a comparison chart of the oxygen reduction polarization curve test results of the catalysts obtained in Example 5, Comparative Examples 1-2, and JM 40% commercial platinum-carbon catalyst provided by the present invention. DETAILED DESCRIPTION

[0037] The following embodiments of the present invention are described in further detail with reference to the accompanying drawings and examples. The following examples are used to illustrate the present invention but are not intended to limit the scope of the present invention.

[0038] like Figure 1 As shown, the present invention provides a quasi-one-dimensional / two-dimensional low-platinum-loaded catalyst, comprising: quasi-two-dimensional graphene formed by partial chemical exfoliation and chemical reduction of a quasi-one-dimensional carbon nanoscroll; the quasi-two-dimensional graphene and the remaining quasi-one-dimensional carbon nanoscroll portion connected to the quasi-two-dimensional graphene are used as structural basic units, bonded in three dimensions by van der Waals forces to form a nanoporous structure; and the surface of the nanoporous structure is loaded with platinum. By constructing an effective nanoporous conductive carbon-based network, it provides rapid electron transport and oxygen molecule diffusion channels for the oxygen reduction reaction at the cathode of a hydrogen fuel cell. At the same time, the network structure can highly stably and densely load small-sized platinum atoms and nanoparticles, providing highly stable and high-density reaction sites for the catalytic reaction, achieving stable output of high current from the catalyst cathode membrane.

[0039] The composite material consists of a sheet of graphene, obtained by oxidative exfoliation and chemical reduction of carbon nanotubes, connected to a twisted and entangled quasi-one-dimensional carbon nanoscroll. The graphene and quasi-one-dimensional carbon nanoscrolls form a quasi-one- / two-dimensional nanoporous structure that improves graphene stacking, enhances the anchoring of platinum particles on the carrier material, and also serves as a mass transfer agent. The sheet of graphene in this structure contains numerous defects and functional groups, making it more effective at dispersing and loading platinum atoms and nanoparticles than quasi-one-dimensional carbon nanoscrolls or carbon nanotubes. It also enhances the material's hydrophilicity, helping the catalyst better manage water.

[0040] Specifically, the nanoporous structure is composed of quasi-two-dimensional graphene formed by partial chemical exfoliation and chemical reduction of quasi-one-dimensional carbon nanoscrolls, and the remaining quasi-one-dimensional carbon nanoscrolls connected to them. These quasi-two-dimensional graphene serves as the structural unit, which is bonded together in three dimensions by van der Waals forces. Even after partial chemical exfoliation, the quasi-one-dimensional carbon nanoscrolls still have a diameter of 20 to 200 nanometers.

[0041] In a preferred embodiment, in the nanoporous structure, the quasi-two-dimensional graphene is peeled off from the surface of the quasi-one-dimensional carbon nanoscroll and then chemically reduced, but the oxidized quasi-two-dimensional graphene obtained by chemical peeling and the quasi-two-dimensional graphene obtained by chemical reduction are always tightly connected to the quasi-one-dimensional carbon nanoscroll through conjugated chemical bonds.

[0042] During the chemical exfoliation process, the quasi-one-dimensional carbon nanoscroll unfolds to yield a partially exfoliated single-layer quasi-two-dimensional graphene and connected quasi-one-dimensional carbon nanoscrolls. The surface of the single-layer oxidized quasi-two-dimensional graphene is rich in defects and functional groups, making it more effective at dispersing and loading platinum atoms and nanoparticles than quasi-one-dimensional carbon nanoscrolls or carbon nanotubes. Quasi-one-dimensional carbon nanoscrolls / oxidized quasi-two-dimensional graphene with platinum adsorption and deposition can be reduced by thermal annealing to yield a low-platinum-loaded platinum-carbon composite material with a quasi-one- / two-dimensional nanoporous structure containing quasi-two-dimensional graphene perfectly connected to the quasi-one-dimensional carbon nanoscrolls. This composite material possesses a highly porous network skeleton composed of quasi-one-dimensional carbon nanoscrolls while ensuring efficient and uniform platinum dispersion. While effectively reducing the mass fraction of platinum loaded, the composite material exhibits excellent oxygen reduction activity and performance stability for hydrogen fuel cell anodes.

[0043] In a preferred embodiment, the loaded platinum can be single atoms, double atoms, multiple atoms and nanoparticles, and the size of the platinum unit dispersed on the surface of the quasi-one / two-dimensional nanoporous structure carbon material is not greater than 5 nanometers.

[0044] The present invention also provides a method for preparing a quasi-one-dimensional / two-dimensional low-platinum-loaded catalyst, comprising the following steps:

[0045] S1, placing the quasi-one-dimensional carbon nanoscroll into a potassium permanganate concentrated sulfuric acid solution and stirring to react to obtain a mixed solution;

[0046] S2, pouring the mixed solution into ice cubes to cool and dilute it, adding deionized water after the ice cubes melt, and then adding hydrogen peroxide to terminate the chemical reaction to obtain a transition solution;

[0047] S3, adding hydrochloric acid and then deionized water to the transition liquid, stirring, and standing, and then filtering and washing the collected solid with deionized water to obtain a quasi-one-dimensional carbon nanoscroll with partially exfoliated oxidized quasi-two-dimensional graphene.

[0048] S4, dispersing the quasi-one-dimensional carbon nanoscroll in deionized water, adding chloroplatinic acid or potassium chloroplatinate solution, stirring evenly and keeping warm, adding hydrazine hydrate or sodium borohydride or glucose for reduction treatment, continuing stirring, and then filtering and drying to obtain a composite powder.

[0049] Specifically, it includes the following steps:

[0050] (1) Place the quasi-one-dimensional carbon nanoscroll in a solution of potassium permanganate and concentrated sulfuric acid and stir for a certain period of time. The diameter of the quasi-one-dimensional carbon nanoscroll raw material ranges from 8 nm to 300 nm. Preferably, the diameter of the quasi-one-dimensional carbon nanoscroll is from 20 nm to 50 nm.

[0051] The mass ratio of potassium permanganate to the quasi-one-dimensional carbon nanoscroll is in the range of 5 to 10; preferably, the mass ratio of potassium permanganate to the quasi-one-dimensional carbon nanoscroll in step (1) is in the range of 6 to 8.

[0052] The reaction temperature is between 0°C and 40°C; preferably, the reaction temperature in step (1) is between 20°C and 30°C. The reaction stirring time is between 30 minutes and 4 hours; preferably, step (1) is stirred for 2 hours.

[0053] (2) Pour the mixed solution obtained in step (1) into ice cubes to cool and dilute, add deionized water after the ice cubes melt, and then add hydrogen peroxide to terminate the chemical reaction. The volume of the ice cubes added is 1.5 to 3 times the volume of the reaction solution in step (1); preferably, the volume of the ice cubes added in step (2) is 2 times the volume of the reaction solution in step (1).

[0054] The volume of deionized water added is 1 to 5 times the volume of the reaction solution in step (1); preferably, the volume of deionized water added in step (2) is 3 times the volume of the reaction solution in step (1).

[0055] The hydrogen peroxide is added until the liquid obtained in step (2) no longer generates bubbles.

[0056] (3) adding hydrochloric acid and then deionized water to the liquid obtained in step (2), stirring, standing, and then filtering and washing the collected solid with deionized water to obtain a quasi-one-dimensional carbon nanoscroll with partially exfoliated oxidized quasi-two-dimensional graphene.

[0057] The molar amount of the added hydrochloric acid is 2 to 6 times the molar amount of potassium permanganate; preferably, the molar amount of the added hydrochloric acid is twice the molar amount of potassium permanganate.

[0058] (4) Dispersing the product obtained in step (3) in deionized water, adding chloroplatinic acid or potassium chloroplatinate solution, stirring evenly and then keeping warm, adding hydrazine hydrate or sodium borohydride or glucose for reduction treatment, continuing stirring, then filtering and drying to obtain the final product. The added platinum-containing compound is chloroplatinic acid or potassium chloroplatinate; preferably, the added platinum-containing compound is chloroplatinic acid. The insulation range is 50°C to 96°C; preferably, when hydrazine hydrate is used as the reducing agent, the temperature is controlled at 70°C to 80°C; preferably, when sodium borohydride is used as the reducing agent, the temperature is controlled at 60°C to 85°C; preferably, when glucose is used as the reducing agent, the temperature is controlled at 85°C to 95°C.

[0059] The following combination Figures 1 to 3 , 5 embodiments of the present invention and 2 comparative examples of the prior art are listed for comparative analysis as follows:

[0060] Example 1:

[0061] Combine Figure 1Step 1: Add 150 ml of concentrated sulfuric acid to a 500 ml beaker, weigh 6.0 g of potassium permanganate, grind it, and slowly add it to the concentrated sulfuric acid solution in the beaker, stir to obtain a mixed solution A; weigh 1.0 g of carbon nanotubes, slowly add it to the mixed solution A in an ice bath, stir at room temperature at a speed of 400 pm for 2 hours, and obtain a mixed solution B.

[0062] Step 2: Take a 1000ml beaker, add 300ml of ice water, pour solution B into the beaker, wait for the ice to melt, add 300ml of deionized water to obtain cooled and diluted solution B, then slowly drip 30wt% H2O2 into the diluted solution B until no bubbles are generated in the solution. Then add 10ml of concentrated hydrochloric acid, stir at 400rpm for 4h, and let it stand overnight. Pour out the supernatant to obtain a precipitate, add deionized water to the precipitate, filter and wash it (centrifuge to neutral), freeze-dry the precipitate after centrifugation to obtain a quasi-one-dimensional carbon nanoscroll with partially exfoliated oxidized quasi-two-dimensional graphene.

[0063] Step 3: Dissolve 50 mg of quasi-one-dimensional carbon nanoscroll powder of oxidized quasi-two-dimensional graphene in 50 ml of deionized water, and ultrasonically disperse for 30 minutes to obtain a dispersion of quasi-one-dimensional carbon nanoscroll of oxidized quasi-two-dimensional graphene. Add 700 μL of chloroplatinic acid solution (H2PtCl6, 3 wt%) to the above dispersion, and stir at 70°C and 900 rpm for 4 hours. Filter the solution after the reaction, and place the filtered solid in a 60°C oven and dry it for 6 hours to obtain a quasi-one / two-dimensional nanoporous structure low-platinum-loaded platinum-carbon composite catalyst.

[0064] Example 2:

[0065] Step 1: Add 150 ml of concentrated sulfuric acid to a 500 ml beaker, weigh 7.0 g of potassium permanganate, grind it, and slowly add it to the concentrated sulfuric acid solution in the beaker, stirring to obtain mixed solution A; weigh 1.0 g of carbon nanotubes, slowly add it to the mixed solution A in an ice bath, and stir at room temperature at 200 rpm for 2 hours to obtain mixed solution B.

[0066] Step 2: Take a 1000ml beaker, add 300ml of ice water, pour solution B into the beaker, wait for the ice to melt, add 300ml of deionized water to obtain cooled and diluted solution B, then slowly drip 30wt% H2O2 into the diluted solution B until no bubbles are generated in the solution. Then add 10ml of concentrated hydrochloric acid, stir at 200rpm for 4h, and let it stand overnight. Pour out the supernatant to obtain a precipitate, add deionized water to the precipitate, filter and wash it (centrifuge to neutral), freeze-dry the precipitate after centrifugation to obtain a quasi-one-dimensional carbon nanoscroll with partially exfoliated oxidized quasi-two-dimensional graphene.

[0067] Step 3: Dissolve 50 mg of quasi-one-dimensional carbon nanoscroll powder of oxidized quasi-two-dimensional graphene in 50 ml of deionized water, and ultrasonically disperse for 30 minutes to obtain a dispersion of quasi-one-dimensional carbon nanoscroll of oxidized quasi-two-dimensional graphene. Add 700 μL of chloroplatinic acid solution (H2PtCl6, 3 wt%) to the above dispersion, and stir at 70°C and 900 rpm for 4 hours. Filter the solution after the reaction, and place the filtered solid in a 60°C oven and dry it for 6 hours to obtain a quasi-one / two-dimensional nanoporous structure low-platinum-loaded platinum-carbon composite catalyst.

[0068] Example 3:

[0069] Step 1: Add 150 ml of concentrated sulfuric acid to a 500 ml beaker, weigh 6.0 g of potassium permanganate, grind it, and slowly add it to the concentrated sulfuric acid solution in the beaker, stirring to obtain mixed solution A; weigh 1.0 g of carbon nanotubes, slowly add it to the mixed solution A in an ice bath, and stir at room temperature at 400 rpm for 2 hours to obtain mixed solution B.

[0070] Step 2: Take a 1000ml beaker, add 300ml of ice water, pour solution B into the beaker, wait for the ice to melt, add 300ml of deionized water to obtain cooled and diluted solution B, then slowly drip 30wt% H2O2 into the diluted solution B until no bubbles are generated in the solution. Then add 10ml of concentrated hydrochloric acid, stir at 400rpm for 4h, and let it stand overnight. Pour out the supernatant to obtain a precipitate, add deionized water to the precipitate, filter and wash it (centrifuge to neutral), freeze-dry the precipitate after centrifugation to obtain a quasi-one-dimensional carbon nanoscroll with partially exfoliated oxidized quasi-two-dimensional graphene.

[0071] Step 3: Dissolve 50 mg of quasi-one-dimensional carbon nanoscroll powder of oxidized quasi-two-dimensional graphene in 50 ml of deionized water, and ultrasonically disperse for 30 minutes to obtain a dispersion of quasi-one-dimensional carbon nanoscroll of oxidized quasi-two-dimensional graphene. Add 700 μL of chloroplatinic acid solution (H2PtCl6, 3 wt%) to the above dispersion, stir evenly, and then drop 3 ml of hydrazine hydrate (85 wt%). Stir at 70 ° C and 900 rpm for 4 hours. After the reaction is completed, the solution is filtered and the filtered solid is placed in a 60 ° C oven and dried for 6 hours to obtain a quasi-one / two-dimensional nanoporous structure low platinum-loaded platinum-carbon composite catalyst.

[0072] Example 4:

[0073] Step 1: Add 150 ml of concentrated sulfuric acid to a 500 ml beaker, weigh 6.0 g of potassium permanganate, grind it, and slowly add it to the concentrated sulfuric acid solution in the beaker, stirring to obtain mixed solution A; weigh 1.0 g of carbon nanotubes, slowly add it to the mixed solution A in an ice bath, and stir at room temperature at 400 rpm for 2 hours to obtain mixed solution B.

[0074] Step 2: Take a 1000ml beaker, add 300ml of ice water, pour solution B into the beaker, wait for the ice to melt, add 300ml of deionized water to obtain cooled and diluted solution B, then slowly drip 30wt% H2O2 into the diluted solution B until no bubbles are generated in the solution. Then add 10ml of concentrated hydrochloric acid, stir at 400rpm for 4h, and let it stand overnight. Pour out the supernatant to obtain a precipitate, add deionized water to the precipitate, filter and wash it (centrifuge to neutral), freeze-dry the precipitate after centrifugation to obtain a quasi-one-dimensional carbon nanoscroll with partially exfoliated oxidized quasi-two-dimensional graphene.

[0075] Step 3: Dissolve 50 mg of quasi-one-dimensional carbon nanoscroll powder of oxidized quasi-two-dimensional graphene in 50 ml of deionized water, and ultrasonically disperse for 30 minutes to obtain a dispersion of quasi-one-dimensional carbon nanoscroll of oxidized quasi-two-dimensional graphene. Add 1000 μL of chloroplatinic acid solution (H2PtCl6, 3 wt%) to the above dispersion, stir evenly, and then drop 3 ml of hydrazine hydrate (85 wt%). Stir at 70 ° C and 900 rpm for 4 hours. After the reaction is completed, the solution is filtered and the filtered solid is placed in a 60 ° C oven and dried for 6 hours to obtain a quasi-one / two-dimensional nanoporous structure low platinum-loaded platinum-carbon composite catalyst.

[0076] Example 5:

[0077] like Figure 3 Step 1: Add 150 ml of concentrated sulfuric acid to a 500 ml beaker, weigh 6.0 g of potassium permanganate, grind it, and slowly add it to the concentrated sulfuric acid solution in the beaker, stirring to obtain mixed solution A; weigh 1.0 g of carbon nanotubes and slowly add it to the mixed solution A in an ice bath, stirring at room temperature at 400 rpm for 2 hours to obtain mixed solution B.

[0078] Step 2: Take a 1000ml beaker, add 300ml of ice water, pour solution B into the beaker, wait for the ice to melt, add 300ml of deionized water to obtain cooled and diluted solution B, then slowly drip 30wt% H2O2 into the diluted solution B until no bubbles are generated in the solution. Then add 10ml of concentrated hydrochloric acid, stir at 400rpm for 4h, and let it stand overnight. Pour out the supernatant to obtain a precipitate, add deionized water to the precipitate, filter and wash it (centrifuge to neutral), freeze-dry the precipitate after centrifugation to obtain a quasi-one-dimensional carbon nanoscroll with partially exfoliated oxidized quasi-two-dimensional graphene.

[0079] Step 3: Dissolve 50 mg of quasi-one-dimensional carbon nanoscroll powder of oxidized quasi-two-dimensional graphene in 50 ml of deionized water and ultrasonically disperse for 30 minutes to obtain a dispersion of quasi-one-dimensional carbon nanoscroll of oxidized quasi-two-dimensional graphene. Add 1314 μL of chloroplatinic acid solution (H2PtCl6, 3 wt%) to the above dispersion and stir evenly. Then, add 3 ml of hydrazine hydrate (85 wt%) dropwise and stir at 70°C and 900 rpm for 4 hours. After the reaction is completed, the solution is filtered and the filtered solid is placed in a 60°C oven and dried for 6 hours to obtain a quasi-one / two-dimensional nanoporous structure low-platinum-loaded platinum-carbon composite catalyst.

[0080] Comparative Example 1:

[0081] Quasi-two-dimensional graphene-supported platinum-based catalyst material was synthesized according to the method described in patent CN114976053 A. The specific steps are as follows:

[0082] Step 1: 500 mg of oxidized quasi-two-dimensional graphene solid was dispersed in 50 ml of deionized water, ultrasonically dispersed for 30 minutes, 500 mg of KOH and 1 g of 1-aminopropyl-3-methylimidazolium bromide were added, and then the mixed solution was refluxed at 80 ° C for 24 hours, while 1 g of LiTFSI solution was slowly added dropwise, stirred at 25 ° C for 3 hours, centrifuged with deionized water, washed, and dried to obtain modified quasi-two-dimensional graphene;

[0083] Step 2: Take 3 mg of the modified quasi-two-dimensional graphene prepared in step 1 and 75 mg of PVP and disperse them in 50 ml of deionized water. Add 1.5 mL of 30 mM H2PtCl6 solution and stir for 3 hours. After stirring, add 7.5 mL of 0.04 M NaBH4 solution and react for 3 hours. After the reaction is completed, centrifuge to obtain a quasi-two-dimensional graphene-supported platinum-based catalyst.

[0084] Linear sweep voltammetry revealed a limiting current density and half-wave potential of 5.35 mA / cm² and 0.76 V, respectively, under acidic conditions. Comparison with Example 5 of this patent and a JM 40% commercial Pt / C catalyst revealed low oxygen reduction catalytic activity under acidic conditions. This is primarily due to the fact that this composite structure hinders the effective exposure of platinum active sites.

[0085] Comparative Example 2:

[0086] The electrocatalyst material of carbon nanotube-supported platinum was synthesized according to the method described in patent CN113871645A. The specific steps are as follows:

[0087] Step 1: 10 mL of 20 mmol / L chloroplatinic acid solution, 10 mL of chloroform, and 145 mg of cetyltrimethylammonium bromide were mixed, ultrasonically dispersed in a container for 30 minutes, and then stirred at 3000 rpm for 1 hour to obtain a mixed solution A;

[0088] Step 2: Dissolve 150 mg of hydroxylated carbon nanotubes (hydroxyl content of 3-5 wt%) in 80 mL of deionized water and disperse by ultrasonication for 30 minutes to obtain solution B;

[0089] Step 3: Pour solution B into solution A, mix, stir for 15 minutes, then add 10 ml of 300 mmol / L NaBH4 solution, stir for 15 minutes to obtain a carbon nanotube-supported platinum nanowire catalyst solution; filter the solution and dry it to prepare a carbon nanotube-supported platinum nanowire catalyst.

[0090] Linear sweep voltammetry revealed a limiting current density and half-wave potential of 5.21 mA / cm² and 0.75 V, respectively, under acidic conditions. Comparison with Example 5 of this patent and a JM 40% commercial Pt / C catalyst revealed a significant performance degradation after 5000 cycles, with a limiting current density of 4.58 mA / cm². This degradation is primarily due to the shedding of active platinum particles in this composite catalyst.

[0091] Experimental procedures for detecting the electrocatalytic activity of catalysts:

[0092] Take 4 mg of the catalyst prepared in the examples and comparative examples, add 760 μl of deionized water, 20 μl of anhydrous ethanol and 40 μl (5 wt%) Nafion solution, and ultrasonically disperse it for 30 minutes to make it into an ink state. Then take 20 μl of the ink and drop it on the glassy carbon electrode and dry it.

[0093] The three-electrode system used a 0.1M perchloric acid solution as the electrolyte, a catalyst-loaded electrode as the working electrode, a silver / silver chloride reference electrode, and a graphite electrode as the counter electrode. LSV curves were then measured using an electrochemical workstation with a scan range of (-0.1-1)V, a scan rate of 10mV / s, and a rotation speed of 1600rpm.

[0094] The performance indicators of the catalysts prepared in the comparative examples of each embodiment are shown in the following table:

[0095]

[0096] Figure 2 This SEM image shows the oxidized quasi-two-dimensional graphene obtained in Example 1 attached to a carbon nanotube support. We can see that a large number of twisted and entangled quasi-one-dimensional carbon nanoscrolls are attached to the surface of the quasi-two-dimensional graphene sheets. The quasi-two-dimensional graphene and the quasi-one-dimensional carbon nanoscrolls form a quasi-one-two-dimensional nanoporous structure, which improves the stacking of the quasi-two-dimensional graphene, enhances the anchoring of platinum particles on the support material, and also serves as a mass transfer agent. The surface of the quasi-two-dimensional graphene sheets in this structure contains a large number of defects and functional groups, making it more effective in dispersing and loading platinum atoms and nanoparticles than quasi-one-dimensional carbon nanoscrolls or carbon nanotubes.

[0097] The LSV performance curves of the carbon nanotube-supported platinum catalyst connected with the oxidized quasi-two-dimensional graphene prepared in Example 5, the quasi-two-dimensional graphene-supported platinum catalyst prepared in Comparative Example 1, and the carbon nanotube-supported platinum catalyst prepared in Comparative Example 2 were measured. Figure 3 As shown in the figure, the LSV performance curves of three different carbon supports are compared. From the above figure, it can be concluded that the half-wave potential, starting point position and limiting current density of the quasi-two-dimensional graphene connected carbon nanotube-supported platinum catalyst prepared by the present invention are greatly improved compared with the single quasi-two-dimensional graphene and carbon nanotube-supported platinum catalyst.

[0098] Furthermore, under the same test conditions, the catalyst of the present invention also showed some improvement compared to the commercial Jm Pt / C catalyst (Pt relative loading of 40 wt %, under the same test conditions). This indicates that the improved carbon support of the present invention can indeed enhance catalytic activity, thereby significantly improving the overall ORR activity of the electrocatalyst.

[0099] The present invention also provides a catalyst material for a hydrogen fuel cell negative electrode, wherein the hydrogen fuel cell negative electrode catalyst material comprises a composite powder prepared by the aforementioned quasi-one / two-dimensional low-platinum-loaded catalyst preparation method.

[0100] The beneficial effects of the present invention are:

[0101] The quasi-one-dimensional carbon nanoscrolls can control the degree of exfoliation during the chemical exfoliation process, thereby achieving a chemical connection between the one-dimensional conductive network and the two-dimensional high-density catalyst-loaded carbon plane. This eliminates the exfoliation of the conductive network matrix of the high-density quasi-two-dimensional graphene plane loaded with platinum particles and carbon black after long-term discharge and the resulting structural instability, as previously described. This structural integration of the conductive skeleton and the high-density carrier surface fundamentally overcomes this structural instability issue. Compared to currently disclosed patented technologies, the catalyst material obtained by this technology has significant advantages in energy density and stability.

[0102] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0103] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A quasi-one-dimensional / two-dimensional low-platinum loaded catalyst, characterized in that: include: Quasi-two-dimensional graphene formed by partial chemical exfoliation and chemical reduction of quasi-one-dimensional carbon nanoscrolls; The quasi-two-dimensional graphene and the remaining quasi-one-dimensional carbon nanoscroll portion connected to the quasi-two-dimensional graphene are used as structural basic units, and are combined by van der Waals forces in three-dimensional space to form a nanoporous structure; and the surface of the nanoporous structure is loaded with platinum; The nanoporous structure is composed of quasi-two-dimensional graphene formed by partial chemical exfoliation and chemical reduction of quasi-one-dimensional carbon nanoscrolls, and the remaining quasi-one-dimensional carbon nanoscrolls connected to it as the basic structural units, which are combined by van der Waals forces in three-dimensional space to form a nanoporous structure; In the nanoporous structure, the quasi-one-dimensional carbon nanoscroll still has a diameter of 20 to 200 nanometers after partial chemical exfoliation.

2. The quasi-one / two-dimensional low-platinum supported catalyst according to claim 1, characterized in that In the nanoporous structure, the quasi-two-dimensional graphene is obtained by peeling off from the surface of the quasi-one-dimensional carbon nanoscroll and then chemically reducing it. However, the graphene oxide obtained by chemical peeling and the quasi-two-dimensional graphene obtained by chemical reduction are always tightly connected to the quasi-one-dimensional carbon nanoscroll through conjugated chemical bonds.

3. The quasi-one / two-dimensional low-platinum supported catalyst according to claim 1, characterized in that The platinum is one or more of single atoms, double atoms, polyatoms or nanoparticles, and the size of the platinum dispersed on the surface of the carbon material with nanoporous structure is not greater than 5 nanometers.

4. A method for preparing a quasi-one / two-dimensional low-platinum-loaded catalyst, characterized in that: The preparation method is used to prepare the quasi-one-dimensional / two-dimensional low-platinum supported catalyst according to any one of claims 1 to 3, comprising the following steps: S1, placing the quasi-one-dimensional carbon nanoscroll into a potassium permanganate concentrated sulfuric acid solution and stirring to react to obtain a mixed solution; The mass ratio of potassium permanganate to quasi-one-dimensional carbon nanoscroll is in the range of 5 to 10; The reaction temperature is between 0°C and 40°C; The reaction stirring time is between 30 minutes and 4 hours; S2, pouring the mixed solution into ice cubes to cool and dilute it, adding deionized water after the ice cubes melt, and then adding hydrogen peroxide to terminate the chemical reaction to obtain a transition solution; S3, adding hydrochloric acid and then deionized water to the transition liquid, stirring, and standing, and then filtering and washing the collected solid with deionized water to obtain a quasi-one-dimensional carbon nanoscroll with partially exfoliated oxidized quasi-two-dimensional graphene; S4, dispersing the quasi-one-dimensional carbon nanoscroll in deionized water, adding chloroplatinic acid or potassium chloroplatinate solution, stirring evenly and keeping warm, adding hydrazine hydrate or sodium borohydride or glucose for reduction treatment, continuing stirring, and then filtering and drying to obtain a composite powder.

5. The method for preparing a quasi-one / two-dimensional low-platinum supported catalyst according to claim 4, wherein: In S1: The diameter of the quasi-one-dimensional carbon nanoscroll raw materials ranges from 8 nanometers to 300 nanometers.

6. The method for preparing a quasi-one / two-dimensional low-platinum supported catalyst according to claim 4, characterized in that: The volume of the ice cubes in S2 is 1.5 to 3 times the volume of the mixed liquid in S1.

7. The method for preparing a quasi-one / two-dimensional low-platinum supported catalyst according to claim 4, characterized in that: The molar amount of hydrochloric acid added in S3 is 2 to 6 times the molar amount of potassium permanganate.

8. The method for preparing a quasi-one / two-dimensional low-platinum supported catalyst according to claim 4, characterized in that: In said S4: The insulation range is 50℃ to 96℃; When using hydrazine hydrate as a reducing agent, the temperature is controlled at 70°C to 80°C; When sodium borohydride is used as the reducing agent, the temperature is controlled between 60°C and 85°C; When glucose is used as the reducing agent, the temperature is controlled at 85°C to 95°C.

9. A catalyst material for a negative electrode of a hydrogen fuel cell, characterized in that: The hydrogen fuel cell negative electrode catalyst material includes a composite powder prepared by the quasi-one / two-dimensional low-platinum-loaded catalyst preparation method as described in claims 4-8.

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