Graphene pore confinement platinum-based nanoparticle material and preparation method thereof

Abstract

The invention discloses a graphene pore confinement platinum-based nanoparticle material and a preparation method thereof, and belongs to the technical field of new energy materials. The method comprises the following steps: placing graphene oxide powder in a mixed solution of nitric acid and hydrogen peroxide, and then carrying out wet oxidation etching treatment in a steel autoclave to obtain etched graphene oxide; placing the etched graphene oxide powder in ultrapure water, and performing ultrasonic stripping to obtain a suspension; mixing a platinum precursor or / and a transition metal precursor with the suspension in a beaker, stirring at a constant temperature, washing and drying to obtain a solid mixture; then, the solid mixture is calcined in an inert atmosphere environment, oxygen groups of graphene oxide are removed and reduced into graphene, meanwhile, the metal precursor is decomposed into metal atoms, and the atoms can be nucleated and grow to form nano-particles. Finally, the nano-particles form holes in the graphene carrier, so that the movement of the nano-particles is limited, the catalytic inactivation is relieved, and the durability of the catalyst is improved.

Description

Technical Field

[0001] The present invention relates to a graphene pore-confined platinum-based nanoparticle material and a preparation method thereof, belonging to the technical field of new energy materials. Background Art

[0002] To achieve large-scale commercialization of proton exchange membrane fuel cells (PEMFCs), key challenges related to cost, durability, and power density must be overcome. The kinetics of the cathodic oxygen reduction reaction (ORR) that determines the power output of PEMFCs is extremely slow. Therefore, a large amount of scarce platinum is required to catalyze the ORR, and its cost exceeds 40% of the cost of PEMFCs. To enable wider application of PEMFCs, it is highly desirable to significantly reduce the platinum content in the catalyst, which has prompted efforts to develop catalysts with lower cost, higher activity, and greater durability. Carbon-supported platinum nanoparticles (NPs) are often used as PEMFC catalysts. A commonly used strategy to improve catalyst performance is to increase the proportion of Pt atoms exposed on the particle surface by reducing the size of Pt NPs. However, small-sized Pt NPs with high surface energy are more prone to sintering to form large particles, resulting in a rapid decline in performance and poor durability during the electrocatalytic reaction process. Aggregation of Pt NPs is one of the main mechanisms leading to sintering, which refers to the migration of Pt NPs under the action of Brownian motion, encountering other particles on the carrier surface, and then fusing into larger particles driven by the reduction of surface energy. The direct result of sintering is the disappearance of smaller NPs and the increase in the volume of larger NPs, leading to a loss of electrochemically active specific surface area. Unfortunately, sintering of carbon-supported metal-based NP catalysts is almost inevitable during the catalytic reaction. Therefore, to improve the long-term durability of the catalyst, it is necessary to enhance the interaction between the carbon carrier and Pt NPs, inhibit the migration and aggregation of Pt NPs, and thus slow down the sintering of Pt NPs. Carbon pore confinement is an effective way to enhance the interaction between the carrier and Pt NPs and inhibit the migration and aggregation of Pt NPs. However, the design and preparation of carbon pore-confined Pt NPs face the following two challenges: (1) how to design suitable carbon carrier pores; (2) how to place Pt NPs into the carbon carrier pores. Summary of the Invention

[0003] To overcome the problems in the background art, the purpose of the present invention is to provide a graphene pore-confined platinum-based nanoparticle material and a preparation method thereof. In this method, graphene oxide powder is subjected to wet chemical oxidation etching treatment in a steel autoclave and then heat-treated. During the heat treatment, the oxygen groups of graphene oxide are removed and reduced to graphene. At the same time, the metal precursor is decomposed into metal atoms, which nucleate and grow to form nanoparticles. Finally, these nanoparticles create pores on the graphene carrier, thereby restricting the movement of the nanoparticles.

[0004] To achieve the above object, the present invention is realized through the following technical solutions:

[0005] A preparation method of a graphene pore-confined platinum-based nanoparticle material, comprising the following steps:

[0006] (1) Dispersing graphene oxide in a nitric acid solution and hydrogen peroxide by ultrasonic treatment to obtain a mixed solution, and then performing hydrothermal treatment to obtain a GO suspension;

[0007] (2) Dialyzing, centrifuging, and drying the GO suspension to obtain dried EGO;

[0008] (3) Dissolving the dried EGO in water, forming an EGO suspension by ultrasonic treatment, taking a platinum precursor or a mixed precursor of a platinum precursor and a transition metal precursor and mixing and stirring it with the EGO suspension to obtain a mixture of a platinum-based precursor and EGO, and then centrifuging and freeze-drying to obtain a freeze-dried mixture;

[0009] (4) Calcining the freeze-dried mixture under an inert gas to obtain a graphene pore-confined platinum-based nanoparticle material.

[0010] More preferably, the graphene oxide is obtained by oxidizing graphite powder and / or carbon nanotubes using the Hummers oxidation method, and the carbon nanotubes are single-walled or multi-walled carbon nanotubes with a certain tube diameter.

[0011] More preferably, the volume ratio of the nitric acid solution to hydrogen peroxide is 100:1 to 30:1, the concentration of the nitric acid solution is 1 to 10 mol / L, the concentration of hydrogen peroxide is 30 wt%, and the concentration of graphene oxide in the mixed solution is 1 - 10 mg / L.

[0012] More preferably, the temperature of the hydrothermal treatment is 50 - 90 °C, and the time is 9 - 20 h.

[0013] More preferably, in step (2), a dialysis bag with a cut-off molecular weight of 14000 Da is used to dialyze the GO suspension.

[0014] More preferably, the platinum precursor is platinum dihydroxytetraammine, chloroplatinic acid, platinum acetylacetonate, platinum chloride, platinum nitrate, platinum ethanolamine hydroxide, etc.; the transition metal precursor is copper dihydroxytetraammine, copper acetylacetonate, copper chloride, copper nitrate, copper sulfate, cobalt dihydroxytetraammine, cobalt acetylacetonate, cobalt chloride, cobalt nitrate, cobalt sulfate.

[0015] More preferably, the mass ratio of the dried EGO to the platinum precursor is 20:1 to 2:1; the mass ratio of the dried EGO to the mixed precursor is 50:1 to 1:1; the mass ratio of the platinum precursor to the transition metal precursor in the mixed precursor is 10:1 to 1:5.

[0016] More preferably, the temperature of the calcination is 800 - 1000 °C, the time is 1 - 3 h, and the heating rate is 10 - 30 °C / min.

[0017] The present invention also claims to protect the graphene pore-confined platinum-based nanoparticle material prepared by the preparation method of the graphene pore-confined platinum-based nanoparticle material.

[0018] More preferably, in the graphene pore-confined platinum-based nanoparticle material, the platinum-based nanoparticles are confined within the graphene pores.

[0019] The main principle of the present invention is as follows: Graphite oxide is exfoliated and deprotonated to form a negatively charged monolayer graphene oxide sol. A metal precursor and the monolayer graphene oxide sol are electrostatically adsorbed to obtain a composite of graphene oxide and the metal precursor. Through heat treatment, the oxygen groups of the graphene oxide are removed and reduced to graphene. At the same time, during the heat treatment process, the metal precursor is converted into metal atoms, and due to their high surface energy, these atoms nucleate and grow to form metal nanoparticles. During the growth process, the metal nanoparticles catalyze the reaction of carbon and oxygen on the graphene oxide to generate carbon monoxide or carbon dioxide, thereby creating pores on the graphene support. Finally, these nanoparticles are confined by the pores they create.

[0020] Advantages of the present invention:

[0021] (1) The present invention can simultaneously prepare pores on the carbon support and place platinum-based nanoparticles into the pores, realizing the confinement of metal nanoparticles, inhibiting their migration and aggregation during the electrocatalytic oxygen reduction reaction process, thereby alleviating catalytic deactivation and enhancing the durability of the catalyst.

[0022] (2) The pores on the graphene support in the present invention contribute to mass transfer in the catalytic reaction, enabling the catalyst to efficiently catalyze the oxygen reduction reaction.

[0023] (3) The method of the present invention has a simple process, low requirements for equipment, low cost, and good industrial application prospects. Description of the Drawings

[0024] Figure 1 It is the X-ray diffraction pattern of the graphene pore-confined platinum nanoparticle material prepared in Example 1 of the present invention.

[0025] Figure 2 It is the scanning electron microscope image of the graphene pore-confined platinum nanoparticle material prepared in Example 1 of the present invention.

[0026] Figure 3 It is the transmission electron microscope image of the graphene pore-confined platinum nanoparticle material prepared in Example 1 of the present invention.

[0027] Figure 4Electrocatalytic oxygen reduction reaction activity comparison chart of the graphene pore-confined platinum nanoparticle material prepared in Example 1 of the present invention and a commercial catalyst.

[0028] Figure 5 SEM image of the graphene pore-confined platinum nanoparticle material prepared in Example 2 of the present invention.

[0029] Figure 6 Electrocatalytic oxygen reduction reaction activity diagram of the graphene pore-confined platinum nanoparticle material prepared in Example 2 of the present invention.

[0030] Figure 7 SEM image of the graphene pore-confined platinum nanoparticle material prepared in Example 3 of the present invention.

[0031] Figure 8 Electrocatalytic oxygen reduction reaction activity diagram of the graphene pore-confined platinum nanoparticle material prepared in Example 3 of the present invention.

[0032] Figure 9 SEM image of the graphene pore-confined Pt-Cu nanoparticle material prepared in Example 4 of the present invention.

[0033] Figure 10 Electrocatalytic oxygen reduction reaction activity diagram of the graphene pore-confined platinum nanoparticle material prepared in Example 4 of the present invention.

[0034] Figure 11 SEM image of the graphene pore-confined Pt-Co nanoparticle material prepared in Example 5 of the present invention.

[0035] Figure 12 Electrocatalytic oxygen reduction reaction activity diagram of the graphene pore-confined platinum nanoparticle material prepared in Example 5 of the present invention. Detailed implementation manners

[0036] The present invention will be further described in detail below with reference to specific embodiments, but the protection scope of the present invention is not limited thereto.

[0037] The graphene oxide used in the examples and comparative examples of the present invention was obtained by oxidizing graphite powder using the Hummers method.

[0038] Example 1

[0039] A preparation method of a graphene pore-confined platinum-based nanoparticle material, comprising the following steps:

[0040] (1) Place 500 mg of graphene oxide (GO) in 50 mL of nitric acid (5 mol L -1 ) and 1.5 mL of hydrogen peroxide (30 wt%) and ultrasonically disperse for 1 h to obtain a suspension with a concentration of 9.7 mg mL -1 ​

[0041] (2) Transfer the suspension to a stainless-steel autoclave lined with 100 mL of polytetrafluoroethylene, and keep it at 90 °C for 12 h to obtain an acid-etched GO (EGO) suspension.

[0042] (3) Dialyze the EGO suspension using a dialysis bag with a cut-off molecular weight of 14000 Da, and then centrifuge the EGO suspension (12000 rpm, 3 times, 10 min each time). Subsequently, transfer it to a vacuum drying oven and dry it for 12 h under the conditions of a vacuum degree of 0.08 Pa and a constant temperature of 60 °C to obtain a mud-like EGO.

[0043] (4) Take 500 mg of dried EGO and dissolve it in 100 mL of deionized water, and ultrasonically form an EGO suspension of 5.0 mg L -1 . Take 190 mg of platinum precursor (tetraammineplatinum(II) dihydroxide, [Pt(NH3)4](OH)2), mix it with the EGO suspension, and magnetically stir it at 30 °C for 24 h to obtain a [Pt(NH3)4] 2+ / EGO mixture.

[0044] (5) Then centrifuge the [Pt(NH3)4] 2+ / EGO mixture in step (4) (12000 rpm, 3 times, 10 min each time), and then transfer it to a freeze dryer to dry the obtained mixture.

[0045] (6) Place the freeze-dried mixture in a nitrogen atmosphere and calcine it at 900 °C for 1.5 h to obtain a graphene-confined PtNPs material.

[0046] Characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), it is confirmed that the graphene-confined PtNPs material is successfully prepared in this example. In the XRD pattern ( Figure 1 ), diffraction peaks appear at 2θ = 39.6°, 46.0°, 67.3°, 81.1°, and 85.6°, corresponding to the crystal plane diffractions of Pt(111), (200), (220), (311), and (222) respectively, indicating the presence of Pt crystals in the graphene-confined platinum-based nanomaterials. It can be seen from the SEM ( Figure 2 ) that Pt particles are distributed in the graphene pores. The TEM ( Figure 3 ) results show that Pt nanoparticles with an average particle size of 2.8 ± 0.7 nm are successfully confined by the graphene pores. The results of electrochemical tests are shown in Figure 4 and Table 1. It can be seen that the mass activity of the graphene-confined PtNPs material is 410 mA / mg Pt) has a higher mass activity (152 mA / mg) than the commercial Pt / C catalyst, indicating that the material has good electrocatalytic oxygen reduction activity. The results of the material's electrochemical tests are shown in Table 2. Pt ) higher, indicating that the material has good electrocatalytic oxygen reduction activity. The results of the material's electrochemical tests are shown in Table 2.

[0047] Example 2

[0048] A preparation method of a graphene pore-confined platinum-based nanoparticle material, comprising the following steps:

[0049] (1) Place 500 mg of graphene oxide (GO) in 100 mL of nitric acid (10 mol L -1 ) and 1.0 mL of hydrogen peroxide (30 wt%), and ultrasonically disperse for 1 h to obtain a suspension with a concentration of 4.9 mg mL -1 .

[0050] (2) Transfer the suspension to a stainless steel autoclave with a 100 mL polytetrafluoroethylene liner, and keep it at 90 °C for 12 h to obtain an acid-etched GO (EGO) suspension.

[0051] (3) Dialyze the EGO suspension using a dialysis bag with a cut-off molecular weight of 14000 Da, then centrifuge the EGO suspension (12000 rpm, 3 times, 10 min each time), and then transfer it to a vacuum drying oven. Under the constant temperature conditions of a vacuum degree of 0.08 Pa and a temperature of 60 °C, dry for 12 hours to obtain a muddy EGO.

[0052] (4) Take 500 mg of dried EGO and dissolve it in 100 mL of deionized water, ultrasonically form an EGO suspension of 5.0 mg L -1 , take 390 mg of platinum precursor (tetraammineplatinum(II) dihydroxide, [Pt(NH3)4](OH)2), mix it with the EGO suspension, and magnetically stir at 30 °C for 24 h to obtain a [Pt(NH3)4] 2+ / EGO mixture.

[0053] (5) Then centrifuge the [Pt(NH3)4] 2+ / EGO mixture in step (4) (12000 rpm, 3 times, 10 min each time), and then transfer it to a freeze dryer to dry the obtained mixture.

[0054] (6) Place the freeze-dried mixture in a nitrogen atmosphere and calcine it at 1000 °C for 1 h to obtain a graphene pore-confined PtNPs material.

[0055] As Figure 5As shown, the Pt particles in the graphene pore-confined PtNPs material prepared in Example 2 are distributed in the graphene pores and are successfully confined by the graphene pores. The electrocatalytic oxygen reduction activity is as Figure 6 shown. The results of the electrochemical tests of the material are shown in Table 1.

[0056] Example 3

[0057] A method for preparing a graphene pore-confined platinum-based nanoparticle material, comprising the following steps:

[0058] (1) Place 500 mg of graphene oxide (GO) in 60 mL of nitric acid (5 mol L -1 ) and 2.0 mL of hydrogen peroxide (30 wt%), and ultrasonically disperse for 1 h to obtain a suspension with a concentration of 8.0 mg mL -1 .

[0059] (2) Transfer the suspension to a stainless steel autoclave lined with 100 mL of polytetrafluoroethylene, and keep it at 90 °C for 9 h to obtain an acid-etched GO (EGO) suspension.

[0060] (3) Dialyze the EGO suspension using a dialysis bag with a cut-off molecular weight of 14000 Da, and then centrifuge the EGO suspension (12000 rpm, 3 times, 10 min each time). Subsequently, transfer it to a vacuum drying oven and dry it for 12 hours under a constant temperature condition with a vacuum degree of 0.08 Pa and a temperature of 60 °C to obtain a muddy EGO.

[0061] (4) Take 500 mg of dried EGO and dissolve it in 100 mL of deionized water, and ultrasonically form an EGO suspension with a concentration of 5.0 mg L -1 . Take 180 mg of a platinum precursor (tetraammineplatinum dihydroxide, [Pt(NH3)4](OH)2), mix it with the EGO suspension, and magnetically stir at 30 °C for 24 h to obtain a [Pt(NH3)4] 2+ / EGO mixture.

[0062] (5) Centrifuge the [Pt(NH3)4] 2+ / EGO mixture in step (4) (12000 rpm, 3 times, 10 min each time), and then transfer it to a freeze dryer to dry the obtained mixture.

[0063] (6) Calcinate the freeze-dried mixture in a nitrogen atmosphere at 800 °C for 3 h to obtain the graphene pore-confined Pt NPs material.

[0064] As Figure 7As shown, the Pt particles in the graphene pore-confined PtNPs material prepared in Example 3 are distributed in the graphene pores and are successfully confined by the graphene pores. The electrocatalytic oxygen reduction activity is as Figure 8 shown. The results of the electrochemical tests of the material are shown in Table 1.

[0065] Example 4

[0066] A method for preparing a graphene pore-confined platinum-based nanoparticle material, comprising the following steps:

[0067] (1) Place 51.5 mg of graphene oxide (GO) in 50 mL of nitric acid (1 mol L -1 ) and 1.5 mL of hydrogen peroxide (30 wt%) and ultrasonically disperse for 1 h to obtain a suspension with a concentration of 1 mg mL -1 .

[0068] (2) Transfer the suspension to a stainless steel autoclave with a 100 mL polytetrafluoroethylene liner and keep it at 50 °C for 20 h to obtain an acid-etched GO (EGO) suspension.

[0069] (3) Dialyze the EGO suspension using a dialysis bag with a cut-off molecular weight of 14,000 Da, then centrifuge the EGO suspension (12,000 rpm, 3 times, 10 min each time), and then transfer it to a vacuum drying oven. Under the constant temperature conditions of a vacuum degree of 0.08 Pa and a temperature of 60 °C, dry for 12 hours to obtain a muddy EGO.

[0070] (4) Take 500 mg of the dried EGO and dissolve it in 100 mL of deionized water, ultrasonically form an EGO suspension of 5.0 mg L -1 , take 180 mg of a platinum precursor (tetraammineplatinum dihydroxide, [Pt(NH3)4](OH)2) and 180 mg of a copper precursor (tetraamminecopper dihydroxide, [Cu(NH3)4](OH)2), mix them with the EGO suspension, and magnetically stir at 30 °C for 24 h to obtain a [Pt(NH3)4] 2+ / EGO mixture.

[0071] (5) Centrifuge the [Pt(NH3)4] 2+ / EGO mixture in step (4) (12,000 rpm, 3 times, 10 min each time), and then transfer it to a freeze dryer to dry the obtained mixture.

[0072] (6) Calcinate the freeze-dried mixture in a nitrogen atmosphere at 900 °C for 1.5 h to obtain a graphene pore-confined Pt-CuNPs material.

[0073] As Figure 9As shown, the Pt-Cu particles in the graphene pore-confined Pt-CuNPs material prepared in Example 4 are distributed in the graphene pores and are successfully confined by the graphene pores, and the electrocatalytic oxygen reduction activity is as Figure 10 shown. The results of the electrochemical tests of the materials are shown in Table 1.

[0074] Example 5

[0075] A preparation method of a graphene pore-confined platinum-based nanoparticle material comprises the following steps:

[0076] (1) Place 500 mg of graphene oxide (GO) in 50 mL of nitric acid (5 mol L -1 ) and 1.5 mL of hydrogen peroxide (30 wt%), and ultrasonically disperse for 1 h to obtain a suspension with a concentration of 9.7 mg mL -1 .

[0077] (2) Transfer the suspension to a stainless steel autoclave lined with 100 mL of polytetrafluoroethylene, and keep it at 90 °C for 12 h to obtain an acid-etched GO (EGO) suspension.

[0078] (3) Dialyze the EGO suspension using a dialysis bag with a cut-off molecular weight of 14,000 Da, and then centrifuge the EGO suspension (12,000 rpm, 3 times in total, 10 min each time). Subsequently, transfer it to a vacuum drying oven, and dry it for 12 h under a constant temperature condition with a vacuum degree of 0.08 Pa and a temperature of 60 °C to obtain a mud-like EGO.

[0079] (4) Take 500 mg of dried EGO and dissolve it in 100 mL of deionized water, and ultrasonically form an EGO suspension with a concentration of 5.0 mg L -1 . Take 9 mg of a platinum precursor (tetraammineplatinum dihydroxide, [Pt(NH3)4](OH)2) and 1 mg of a cobalt precursor (tetraamminecobalt dihydroxide, [Co(NH3)4](OH)2), mix them with the EGO suspension, and magnetically stir at 30 °C for 24 h to obtain a [Pt(NH3)4] 2+ / EGO mixture.

[0080] (5) Then centrifuge the [Pt(NH3)4] 2+ / EGO mixture in step (4) (12,000 rpm, 3 times in total, 10 min each time), and then transfer it to a freeze dryer to dry the obtained mixture.

[0081] (6) Place the freeze-dried mixture in a nitrogen atmosphere and calcine it at 900 °C for 1.5 h to obtain a graphene pore-confined Pt-CoNPs material.

[0082] As Figure 11As shown, the Pt-Co particles in the graphene pore-confined Pt-Co NPs material prepared in Example 5 are distributed in the graphene pores and are successfully confined by the graphene pores. The electrocatalytic oxygen reduction activity is as Figure 12 shown. The results of the electrochemical tests of the materials are shown in Table 1.

[0083] Comparative Example 1

[0084] A method for preparing a graphene / platinum-based nanoparticle material, comprising the following steps:

[0085] (1) Place 500 mg of graphene oxide (GO) in 50 mL of nitric acid (5 mol L -1 ) and 1.5 mL of hydrogen peroxide (30 wt%) and ultrasonically disperse for 1 h to obtain a suspension with a concentration of 9.7 mg mL -1 .

[0086] (2) Keep the suspension at 90 °C for 12 h to obtain an acid-etched GO (EGO) suspension.

[0087] (3) Dialyze the EGO suspension using a dialysis bag with a cut-off molecular weight of 14,000 Da, and then centrifuge the EGO suspension (12,000 rpm, 3 times, 10 min each time). Subsequently, transfer it to a vacuum drying oven and dry it for 12 h under a constant temperature condition with a vacuum degree of 0.08 Pa and a temperature of 60 °C to obtain a muddy EGO.

[0088] (4) Take 500 mg of dry EGO and dissolve it in 100 mL of deionized water, ultrasonically form an EGO suspension with a concentration of 5.0 mg L -1 . Take 390 mg of a platinum precursor (tetraammineplatinum dihydroxide, [Pt(NH3)4](OH)2), mix it with the EGO suspension, and magnetically stir at 30 °C for 24 h to obtain a [Pt(NH3)4] 2+ / EGO mixture.

[0089] (5) Centrifuge the [Pt(NH3)4] 2+ / EGO mixture in step (4) (12,000 rpm, 3 times, 10 min each time), and then transfer it to a freeze dryer to dry the obtained mixture.

[0090] (6) Calcine the freeze-dried mixture in a nitrogen atmosphere at 900 °C for 1.5 h to obtain a graphene / Pt NPs material. The results of the electrochemical tests are shown in Table 1.

[0091] Comparative Example 2

[0092] A method for preparing a graphene / platinum-based nanoparticle material, comprising the following steps:

[0093] (1) Dissolve 500 mg of graphene in 100 mL of deionized water and ultrasonically form an EGO suspension of 5.0 mg L -1 . Take 390 mg of platinum precursor (tetraammineplatinum(II) dihydroxide, [Pt(NH3)4](OH)2), mix it with the EGO suspension, and magnetically stir at a constant temperature of 30 °C for 24 h to obtain a [Pt(NH3)4] 2+ / EGO mixture.

[0094] (2) Then centrifuge the [Pt(NH3)4] 2+ / EGO mixture in step (1) (12000 rpm, 3 times in total, 10 min each time), and then transfer it to a freeze dryer to dry the obtained mixture.

[0095] (3) Calcinate the freeze-dried mixture in a nitrogen atmosphere at 900 °C for 1.5 h to obtain a graphene / Pt NPs material. The results of the electrochemical test of the material are shown in Table 1.

[0096] Table 1

[0097]

[0098] As can be seen from Table 1, for the graphene pore-confined platinum-based nanoparticle materials prepared in Examples 1-5 of the present invention, the mass activity decay rate after 30,000 times of accelerated durability test (ADT 30K 0.6-0.95V) at 0.6-0.9 V is at a relatively low level compared with Comparative Examples 1-2, which fully shows that the materials prepared in the present invention have excellent durability. The new materials prepared by the preparation method of the present invention can confine platinum-based nanoparticles in carbon pores, effectively enhancing the interaction between graphene and platinum-based nanoparticles. At the same time, by using the confinement effect of carbon pores on platinum-based nanoparticles, the probability of nanoparticles migrating, falling off, and aggregating during long-term electrochemical reactions is reduced, ultimately improving the electrocatalytic activity and durability of the graphene pore-confined platinum-based nanoparticle materials.

[0099] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention.

Claims

1. A preparation method of a graphene-confined platinum-based nanoparticle material, characterized in that: It includes the following steps: (1) Graphene oxide is ultrasonically dispersed in a mixed solution of nitric acid solution and hydrogen peroxide to obtain a mixed solution, and then hydrothermally treated to obtain a GO suspension; (2) The GO suspension is dialyzed, centrifuged, and dried to obtain dry EGO; (3) The dry EGO is dissolved in water and ultrasonically treated to form an EGO suspension. A platinum precursor or a mixed precursor of a platinum precursor and a transition metal precursor is mixed and stirred with the EGO suspension to obtain a mixture of a platinum-based precursor and EGO, and then centrifuged and freeze-dried to obtain a freeze-dried mixture; (4) The freeze-dried mixture is calcined under an inert gas to obtain a graphene-confined platinum-based nanoparticle material.

2. The preparation method of the graphene-confined platinum-based nanoparticle material according to claim 1, characterized in that: The graphite oxide is obtained by oxidizing graphite powder and / or carbon nanotubes using the Hummers method, and the carbon nanotubes are single-walled or multi-walled carbon nanotubes with a tube diameter of 3. The preparation method of the graphene-confined platinum-based nanoparticle material according to claim 1, wherein: The volume ratio of the nitric acid solution to hydrogen peroxide is 100:1 to 30:1, the concentration of the nitric acid solution is 1 to 10 mol / L, the concentration of hydrogen peroxide is 30 wt%, and the concentration of graphene oxide in the mixed solution is 1 to 10 mg / L.

4. The preparation method of the graphene-confined platinum-based nanoparticle material according to claim 1, wherein: The temperature of the hydrothermal treatment is 50 - 90 °C, and the time is 9 - 20 h.

5. The preparation method of the graphene-confined platinum-based nanoparticle material according to claim 1, characterized in that: In step (2), a dialysis bag with a cut-off molecular weight of 14000 Da is used to dialyze the GO suspension.

6. The preparation method of the graphene pore-confined platinum-based nanoparticle material according to claim 1, wherein: The platinum precursor is dihydroxytetraammineplatinum, chloroplatinic acid, platinum acetylacetonate, platinum chloride, platinum nitrate, or ethanolamine hydroxypalladium; the transition metal precursor is dihydroxytetraamminecopper, copper acetylacetonate, copper chloride, copper nitrate, copper sulfate, dihydroxytetraamminecobalt, cobalt acetylacetonate, cobalt chloride, cobalt nitrate, or cobalt sulfate.

7. The preparation method of the graphene-confined platinum-based nanoparticle material according to claim 1, wherein: The mass ratio of the dry EGO to the platinum precursor is 20:1 to 2:1; the mass ratio of the dry EGO to the mixed precursor is 50:1 to 1:1; the mass ratio of the platinum precursor to the transition metal precursor in the mixed precursor is 10:1 to 1:

5.

8. The preparation method of the graphene-confined platinum-based nanoparticle material according to claim 1, wherein: The temperature of the calcination is 800 - 1000 °C, the time is 1 - 3 h, and the heating rate is 10 - 30 min.

9. A graphene-confined platinum-based nanoparticle material prepared by the method for preparing a graphene-confined platinum-based nanoparticle material according to any one of claims 1 - 8.

10. The graphene pore-confined platinum-based nanoparticle material according to claim 9, characterized in that: The platinum-based nanoparticles are confined within the graphene pores.

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