Covalent organic framework-derived low-load Pt / C catalyst and its preparation method and application

Abstract

The present invention discloses a low-load Pt / C catalyst derived from a covalent organic framework, a preparation method, and an application thereof, and belongs to the field of electrocatalysis. The present invention utilizes a covalent organic framework material coordinated with a platinum metal salt as a precursor, and synthesizes a low-load integrated Pt / C nanomaterial by a simple carbonization method in a mixed atmosphere of argon / ammonia. Compared with commercial Pt / C with a mass fraction of 20%, the Pt / C nanomaterial prepared by the present invention has an oxygen reduction performance far greater than that of commercial Pt / C, and a stability performance superior to that of commercial Pt / C. Due to its higher nitrogen content and porous characteristics, the catalyst of the present invention has better catalytic performance and stability than commercial Pt / C, and the obtained low-load Pt / C catalyst derived from a covalent organic framework exhibits excellent redox catalytic performance. The catalytic activity decays only after 10,000 cycles. The method of the present invention is simple to operate, highly controllable, and has a certain degree of universality.

Description

Technical Field

[0001] The present invention relates to a covalent organic framework-derived low-load Pt / C catalyst and a preparation method and application thereof, belonging to the technical field of electrocatalysis. Background Art

[0002] With the acceleration of industrialization and the growing severity of environmental and energy challenges, more and more countries around the world are focusing on clean, efficient, and safe energy conversion technologies. Fuel cells are energy devices that convert the chemical energy in small molecule fuels such as ethanol, methanol, hydrogen, and formic acid into electrical energy. They offer advantages such as high efficiency, safety, and environmental friendliness. Since the concept of fuel cells was first proposed in the 1740s, they have undergone over 170 years of development. The operating efficiency and power density of fuel cells often depend on the selection of electrolyte and catalyst materials. The catalyst plays a crucial role, in part determining the development of fuel cell technology. Carbon-supported platinum-based catalysts, due to their excellent catalytic performance, are considered the most ideal catalyst material for fuel cells and occupy a key position in fuel cell applications. However, their high cost and scarce resources have limited their large-scale commercial application. Therefore, reducing the platinum loading while improving its catalytic activity and stability is crucial to promoting the development of fuel cells.

[0003] Existing commercial platinum-carbon catalysts have a high loading, with a platinum loading mass fraction of ≥20%, and require carbon loading treatment, which is costly and has limited catalytic activity and stability.

[0004] In response to the above problems, this application is filed. Summary of the Invention

[0005] In order to solve the above problems, the present invention provides a covalent organic framework-derived low-load Pt / C catalyst, a preparation method and application thereof. The method of the present invention is simple in process and relatively low in cost. The prepared low-load Pt / C catalytic material has excellent oxidogen activity and stability. The half-wave potential under acidic conditions is 0.90 V, which is much higher than the half-wave potential of commercial Pt / C (0.84 V). It shows signs of attenuation only after 10,000 cycles, and can be applied to the field of fuel cells.

[0006] The first object of the present invention is to provide a method for preparing a low-load Pt / C catalyst derived from a covalent organic framework, comprising the following steps:

[0007] S1: adding a platinum metal salt and a covalent organic framework precursor to an ethanol solution, and refluxing and condensing the solution sufficiently to obtain a covalent organic framework precursor coordinated with platinum metal ions;

[0008] S2: The covalent organic framework precursor coordinated with platinum metal ions obtained in step S1 is subjected to pyrolysis treatment in an atmosphere of a mixed gas of argon and ammonia, and the derived low-load Pt / C catalyst is obtained after cooling.

[0009] Preferably, the preparation method of the covalent organic framework in step S1 is as follows: 15.00 mg 0.024 mmol of tetrakis(4-formylphenyl)pyrene and 7.58 mg 0.048 mmol of 1,4-phenyldiacetonitrile are selected as reaction monomers, added into a sealed glass tube containing 1 ml of a 1 / 5 volume mixed solution of mesitylene / 1,4-dioxane and 0.1 mL of 4 M NaOH, heated to 90° C., and reacted for 3 days to obtain a covalent organic framework.

[0010] Preferably, the covalent organic framework is sp 2 Covalent organic frameworks.

[0011] Preferably, the mass ratio of the platinum metal salt to the covalent organic framework in step S1 is 0.1-0.4.

[0012] Preferably, the platinum metal salt is chloroplatinic acid, sodium chloroplatinate, or potassium chloroplatinate.

[0013] Preferably, the pyrolysis treatment conditions in step S2 are: pyrolysis for 2-4 h, a temperature of 900-1000° C., and a heating rate of 2-5° C. / min.

[0014] Preferably, the volume ratio of argon gas to ammonia gas in step S2 is 10:1.

[0015] Using the above technical solution, platinum metal salt and covalent organic framework are used as precursors under a mixed atmosphere. After sufficient reflux condensation, the covalent organic framework precursor coordinated with platinum metal ions is extracted using a rotary evaporator. The above precursor is heated to a certain temperature in a tubular furnace for pyrolysis. After the pyrolysis is completed, a low-load Pt / C catalyst derived from the covalent organic framework is obtained.

[0016] The second object of the present invention is to provide a loaded Pt / C catalyst prepared by the above method, wherein the mass fraction of platinum in the low loaded Pt / C catalyst is 8%-12%.

[0017] The third object of the present invention is to provide the use of the low-loaded Pt / C catalyst in cathode materials, fuel cells or fuel cell driving devices.

[0018] Beneficial effects of the present invention:

[0019] (1) The present invention utilizes covalent organic framework materials as precursors to directly prepare carbon-loaded integrated catalysts with low Pt content, thus avoiding the secondary carbon carrier loading process required for the traditional nano-hydrothermal method to prepare platinum-based nanocatalysts.

[0020] (2) Due to its high nitrogen content and porous nature, the catalyst of the present invention has superior catalytic performance and stability to commercial Pt / C. In particular, when the mass ratio of chloroplatinic acid to the covalent organic framework precursor is 0.2, the temperature is raised to 900°C at a heating rate of 5°C / min, the pyrolysis time is 3 h, and the covalent organic framework-derived low-load Pt / C catalyst obtained after cooling exhibits excellent redox catalytic performance. The catalytic activity only decays after 10,000 cycles. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a structural diagram of the covalent organic framework precursor used in the present invention.

[0022] Figure 2 Transmission electron microscopy (TEM) images of Pt / C (named Pt / CN-900, Pt / CN-950, and Pt / CN-1000, respectively) prepared at different temperatures under an argon / ammonia mixed atmosphere as prepared in Examples 1-3, where Figure 2 a is Pt / CN-900, Figure 2 b is Pt / CN-950, Figure 2 c is Pt / CN-1000.

[0023] Figure 3 These are the X-ray diffraction patterns of Pt / CN-900, Pt / CN-950, and Pt / CN-1000 prepared in Examples 1-3.

[0024] Figure 4 The platinum content in the Pt / CN-900, Pt / CN-950, and Pt / CN-1000 samples prepared in Examples 1-3.

[0025] Figure 5 These are the oxygen reduction polarization curves of Pt / CN-900, Pt / CN-950, Pt / CN-1000 and commercial Pt / C prepared in Examples 1-3.

[0026] Figure 6 These are the stability test results of Pt / CN-900, Pt / CN-950, Pt / CN-1000 and commercial Pt / C prepared in Examples 1-3.

[0027] Figure 7 The power density results of Pt / CN-900 prepared in Example 1 and commercial Pt / C tested in H2-O2 fuel cells.

[0028] Figure 8 TEM images of samples prepared by pyrolysis under different gas atmospheres.

[0029] Figure 9 This is a transmission electron microscope image of the sample prepared in Example 5 using platinum acetylacetonate as the platinum source.

[0030] Figure 10 For comparative example 1, referring to Example 1, a transmission electron microscope image of a sample prepared by changing the covalent organic framework precursor to a linear polymer polyaniline is shown. DETAILED DESCRIPTION

[0031] In order to make the technical means, creative features, objectives and effects achieved by the present invention easier to understand, the present invention is further described below in conjunction with specific implementation methods.

[0032] Example 1

[0033] A method for preparing a low-load Pt / C catalyst derived from a covalent organic framework comprises the following steps:

[0034] S1: 50 mg of the covalent organic framework and 100 μL (100 mg / mL) chloroplatinic acid solution were added to 100 mL of ethanol solution. After sufficient reflux condensation, the covalent organic framework coordinated with the platinum metal ion was extracted using a rotary evaporator;

[0035] S2: The obtained covalent organic framework coordinated with platinum metal ions was transferred to a tubular furnace for pyrolysis in an argon / ammonia atmosphere. The mixture was heated to 900°C at a heating rate of 5°C / min and a pyrolysis time of 3 h. After cooling to room temperature, a low-load Pt / C catalyst derived from the covalent organic framework was obtained, which was named Pt / CN-900.

[0036] In this embodiment, the preparation method of the covalent organic framework is as follows: tetrakis(4-formylphenyl)pyrene (PY, 15.00 mg, 0.024 mmol) and 1,4-phenyldiacetonitrile (PA, 7.58 mg, 0.048 mmol) are selected as reaction monomers, added to a sealed glass tube containing a mixed solution of mesitylene / 1,4-dioxane (1 ml, 1 / 5 volume) and NaOH (0.1 mL, 4 M), heated to 90°C, and reacted for three days to obtain a covalent organic framework.

[0037] In this embodiment, the volume ratio of argon gas to ammonia gas is 10:1.

[0038] Example 2

[0039] A method for preparing a low-load Pt / C catalyst derived from a covalent organic framework comprises the following steps:

[0040] S1: 50 mg of the covalent organic framework and 100 μL (100 mg / mL) chloroplatinic acid solution were added to 100 mL of ethanol solution. After sufficient reflux condensation, the covalent organic framework coordinated with the platinum metal ion was extracted using a rotary evaporator;

[0041] S2: The obtained covalent organic framework coordinated with platinum metal ions was transferred to a tubular furnace for pyrolysis in an argon / ammonia atmosphere. The mixture was heated to 950°C at a heating rate of 5°C / min and a pyrolysis time of 3 h. After cooling to room temperature, a low-loaded Pt / C catalyst derived from the covalent organic framework was obtained, named Pt / CN-950.

[0042] In this embodiment, the preparation method of the covalent organic framework is as follows: tetrakis(4-formylphenyl)pyrene (PY, 15.00 mg, 0.024 mmol) and 1,4-phenyldiacetonitrile (PA, 7.58 mg, 0.048 mmol) are selected as reaction monomers, added to a sealed glass tube containing a mixed solution of mesitylene / 1,4-dioxane (1 ml, 1 / 5 volume) and NaOH (0.1 mL, 4 M), heated to 90°C, and reacted for three days to obtain a covalent organic framework.

[0043] In this embodiment, the volume ratio of argon gas to ammonia gas is 10:1.

[0044] Example 3

[0045] A method for preparing a low-load Pt / C catalyst derived from a covalent organic framework comprises the following steps:

[0046] S1: 50 mg of the covalent organic framework and 100 μL (100 mg / mL) chloroplatinic acid solution were added to 100 mL of ethanol solution. After sufficient reflux condensation, the covalent organic framework coordinated with the platinum metal ion was extracted using a rotary evaporator;

[0047] S2: The obtained covalent organic framework coordinated with platinum metal ions was transferred to a tubular furnace for pyrolysis in an argon / ammonia atmosphere. The mixture was heated to 1000°C at a heating rate of 5°C / min and a pyrolysis time of 3 h. After cooling to room temperature, a low-load Pt / C catalyst derived from the covalent organic framework was obtained, which was named Pt / CN-1000.

[0048] In this embodiment, the preparation method of the covalent organic framework is as follows: tetrakis(4-formylphenyl)pyrene (PY, 15.00 mg, 0.024 mmol) and 1,4-phenyldiacetonitrile (PA, 7.58 mg, 0.048 mmol) are selected as reaction monomers, added to a sealed glass tube containing a mixed solution of mesitylene / 1,4-dioxane (1 ml, 1 / 5 volume) and NaOH (0.1 mL, 4 M), heated to 90°C, and reacted for three days to obtain a covalent organic framework.

[0049] In this embodiment, the volume ratio of argon gas to ammonia gas is 10:1.

[0050] Example 4

[0051] A method for preparing a low-load Pt / C catalyst derived from a covalent organic framework comprises the following steps:

[0052] S1: 50 mg of the covalent organic framework and 200 μL (100 mg / mL) chloroplatinic acid solution were added to 100 mL of ethanol solution. After sufficient reflux condensation, the covalent organic framework coordinated with the platinum metal ion was extracted using a rotary evaporator;

[0053] S2: The obtained covalent organic framework coordinated with platinum metal ions was transferred to a tubular furnace for pyrolysis in an argon / ammonia atmosphere. The mixture was heated to 900°C at a heating rate of 2°C / min and a pyrolysis time of 2 h. After cooling to room temperature, a low-loaded Pt / C catalyst derived from the covalent organic framework was obtained, which was named Pt / CN-900.

[0054] In this embodiment, the preparation method of the covalent organic framework is as follows: tetrakis(4-formylphenyl)pyrene (PY, 15.00 mg, 0.024 mmol) and 1,4-phenyldiacetonitrile (PA, 7.58 mg, 0.048 mmol) are selected as reaction monomers, added to a sealed glass tube containing a mixed solution of mesitylene / 1,4-dioxane (1 ml, 1 / 5 volume) and NaOH (0.1 mL, 4 M), heated to 90°C, and reacted for three days to obtain a covalent organic framework.

[0055] In this embodiment, the volume ratio of argon gas to ammonia gas is 10:1.

[0056] Example 5

[0057] A method for preparing a low-load Pt / C catalyst derived from a covalent organic framework comprises the following steps:

[0058] S1: 50 mg of the covalent organic framework and 300 μL (100 mg / mL) chloroplatinic acid solution were added to 100 mL of ethanol solution. After sufficient reflux condensation, the covalent organic framework coordinated with the platinum metal ion was extracted using a rotary evaporator;

[0059] S2: The obtained covalent organic framework coordinated with platinum metal ions was transferred to a tubular furnace for pyrolysis in an argon / ammonia atmosphere. The mixture was heated to 900°C at a heating rate of 3°C / min and a pyrolysis time of 4 h. After cooling to room temperature, a low-loaded Pt / C catalyst derived from the covalent organic framework was obtained, which was named Pt / CN-900.

[0060] In this embodiment, the preparation method of the covalent organic framework is as follows: tetrakis(4-formylphenyl)pyrene (PY, 15.00 mg, 0.024 mmol) and 1,4-phenyldiacetonitrile (PA, 7.58 mg, 0.048 mmol) are selected as reaction monomers, added to a sealed glass tube containing a mixed solution of mesitylene / 1,4-dioxane (1 ml, 1 / 5 volume) and NaOH (0.1 mL, 4 M), heated to 90°C, and reacted for three days to obtain a covalent organic framework.

[0061] In this embodiment, the volume ratio of argon gas to ammonia gas is 10:1.

[0062] Example 6

[0063] A method for preparing a low-load Pt / C catalyst derived from a covalent organic framework comprises the following steps:

[0064] S1: 50 mg of the covalent organic framework and 400 μL (100 mg / mL) chloroplatinic acid solution were added to 100 mL of ethanol solution. After sufficient reflux condensation, the covalent organic framework coordinated with the platinum metal ion was extracted using a rotary evaporator;

[0065] S2: The obtained covalent organic framework coordinated with platinum metal ions was transferred to a tubular furnace for pyrolysis in an argon / ammonia atmosphere. The mixture was heated to 900°C at a heating rate of 3°C / min and a pyrolysis time of 2 h. After cooling to room temperature, a low-loaded Pt / C catalyst derived from the covalent organic framework was obtained, which was named Pt / CN-900.

[0066] In this embodiment, the preparation method of the covalent organic framework is as follows: tetrakis(4-formylphenyl)pyrene (PY, 15.00 mg, 0.024 mmol) and 1,4-phenyldiacetonitrile (PA, 7.58 mg, 0.048 mmol) are selected as reaction monomers, added to a sealed glass tube containing a mixed solution of mesitylene / 1,4-dioxane (1 ml, 1 / 5 volume) and NaOH (0.1 mL, 4 M), heated to 90°C, and reacted for three days to obtain a covalent organic framework.

[0067] In this embodiment, the volume ratio of argon gas to ammonia gas is 10:1.

[0068] Example 7

[0069] A method for preparing a low-load Pt / C catalyst derived from a covalent organic framework comprises the following steps:

[0070] S1: 50 mg of the covalent organic framework and 100 μL (100 mg / mL) sodium chloroplatinate solution were added to 100 mL of ethanol solution. After sufficient reflux condensation, the covalent organic framework coordinated with the platinum metal ion was extracted using a rotary evaporator;

[0071] S2: The obtained covalent organic framework coordinated with platinum metal ions was transferred to a tubular furnace for pyrolysis in an argon / ammonia atmosphere. The mixture was heated to 900°C at a heating rate of 5°C / min and a pyrolysis time of 3 h. After cooling to room temperature, a low-loaded Pt / C catalyst derived from the covalent organic framework was obtained.

[0072] In this embodiment, the preparation method of the covalent organic framework is as follows: tetrakis(4-formylphenyl)pyrene (PY, 15.00 mg, 0.024 mmol) and 1,4-phenyldiacetonitrile (PA, 7.58 mg, 0.048 mmol) are selected as reaction monomers, added to a sealed glass tube containing a mixed solution of mesitylene / 1,4-dioxane (1 ml, 1 / 5 volume) and NaOH (0.1 mL, 4 M), heated to 90°C, and reacted for three days to obtain a covalent organic framework.

[0073] In this embodiment, the volume ratio of argon gas to ammonia gas is 10:1.

[0074] Example 8

[0075] A method for preparing a low-load Pt / C catalyst derived from a covalent organic framework comprises the following steps:

[0076] S1: 50 mg of the covalent organic framework and 200 μL (100 mg / mL) potassium chloroplatinate solution were added to 100 mL of ethanol solution. After sufficient reflux condensation, the covalent organic framework coordinated with the platinum metal ion was extracted using a rotary evaporator;

[0077] S2: The obtained covalent organic framework coordinated with platinum metal ions was transferred to a tubular furnace for pyrolysis in an argon / ammonia atmosphere. The mixture was heated to 950°C at a heating rate of 3°C / min and a pyrolysis time of 4 h. After cooling to room temperature, a low-loaded Pt / C catalyst derived from the covalent organic framework was obtained.

[0078] In this embodiment, the preparation method of the covalent organic framework is as follows: tetrakis(4-formylphenyl)pyrene (PY, 15.00 mg, 0.024 mmol) and 1,4-phenyldiacetonitrile (PA, 7.58 mg, 0.048 mmol) are selected as reaction monomers, added to a sealed glass tube containing a mixed solution of mesitylene / 1,4-dioxane (1 ml, 1 / 5 volume) and NaOH (0.1 mL, 4 M), heated to 90°C, and reacted for three days to obtain a covalent organic framework.

[0079] In this embodiment, the volume ratio of argon gas to ammonia gas is 10:1.

[0080] Example 9

[0081] A method for preparing a low-load Pt / C catalyst derived from a covalent organic framework comprises the following steps:

[0082] S1: 50 mg of the covalent organic framework and 300 μL (100 mg / mL) sodium chloroplatinate solution were added to 100 mL of ethanol solution. After sufficient reflux condensation, the covalent organic framework coordinated with the platinum metal ion was extracted using a rotary evaporator;

[0083] S2: The obtained covalent organic framework coordinated with platinum metal ions was transferred to a tubular furnace for pyrolysis in an argon / ammonia atmosphere. The mixture was heated to 1000°C at a heating rate of 5°C / min and a pyrolysis time of 2 h. After cooling to room temperature, a low-loaded Pt / C catalyst derived from the covalent organic framework was obtained.

[0084] In this embodiment, the preparation method of the covalent organic framework is as follows: tetrakis(4-formylphenyl)pyrene (PY, 15.00 mg, 0.024 mmol) and 1,4-phenyldiacetonitrile (PA, 7.58 mg, 0.048 mmol) are selected as reaction monomers, added to a sealed glass tube containing a mixed solution of mesitylene / 1,4-dioxane (1 ml, 1 / 5 volume) and NaOH (0.1 mL, 4 M), heated to 90°C, and reacted for three days to obtain a covalent organic framework.

[0085] In this embodiment, the volume ratio of argon gas to ammonia gas is 10:1.

[0086] Example 10

[0087] A method for preparing a low-load Pt / C catalyst derived from a covalent organic framework comprises the following steps:

[0088] S1: 50 mg of the covalent organic framework and 200 μL (100 mg / mL) potassium chloroplatinate solution were added to 100 mL of ethanol solution. After sufficient reflux condensation, the covalent organic framework coordinated with the platinum metal ion was extracted using a rotary evaporator;

[0089] S2: The obtained covalent organic framework coordinated with platinum metal ions was transferred to a tubular furnace for pyrolysis in an argon / ammonia atmosphere. The mixture was heated to 900°C at a heating rate of 2°C / min and a pyrolysis time of 4 h. After cooling to room temperature, a low-loaded Pt / C catalyst derived from the covalent organic framework was obtained.

[0090] In this embodiment, the preparation method of the covalent organic framework is as follows: tetrakis(4-formylphenyl)pyrene (PY, 15.00 mg, 0.024 mmol) and 1,4-phenyldiacetonitrile (PA, 7.58 mg, 0.048 mmol) are selected as reaction monomers, added to a sealed glass tube containing a mixed solution of mesitylene / 1,4-dioxane (1 ml, 1 / 5 volume) and NaOH (0.1 mL, 4 M), heated to 90°C, and reacted for three days to obtain a covalent organic framework.

[0091] In this embodiment, the volume ratio of argon gas to ammonia gas is 10:1.

[0092] The structure diagram of the covalent organic framework precursor used in the present invention is shown in Figure 1 The present invention adopts a typical representative sp 2 Covalent organic framework structure with periodic structure.

[0093] Comparative Example 1

[0094] Commercial Pt / C catalyst with a platinum mass fraction of 20%.

[0095] Comparative Example 2

[0096] The difference from Example 1 is that the gas atmosphere in step S2 is argon.

[0097] Comparative Example 3

[0098] The difference from Example 1 is that the gas atmosphere in step S2 is hydrogen / argon, and the volume ratio of the two is 10:1.

[0099] Comparative Example 4

[0100] The difference from Example 1 is that the chloroplatinic acid in S1 is replaced by platinum acetylacetonate.

[0101] Comparative Example 5

[0102] The difference from Example 1 is that: sp 2 Covalent organic frameworks are replaced by linear polymers.

[0103] Test Example 1

[0104] Test groups: Examples 1-3.

[0105] Test method:

[0106] (1) The products prepared in Examples 1-3 were characterized by transmission electron microscopy;

[0107] (2) The products prepared in Examples 1-3 were characterized by X-ray diffraction;

[0108] (3) The platinum content of the products prepared in Examples 1-3 was tested.

[0109] Test results:

[0110] (1) Figure 2 These are transmission electron micrographs of Pt / CN-900, Pt / CN-950, and Pt / CN-1000. It can be seen from the figure that the size of the metal Pt nanoparticles is about 4-6 nm and is evenly distributed on the surface of the carbon substrate.

[0111] (2) Figure 3 These are the X-ray diffraction patterns of Pt / CNx (x = 900, 950, 1000). From their diffraction peaks, we can get their phase information, which is face-centered cubic Pt metal.

[0112] (3) Figure 4 This is a comparison chart of the platinum content in Pt / CN-900, Pt / CN-950, and Pt / CN-1000 samples. It can be seen from the figure that the platinum content in the product prepared by the present invention is between 8% and 12%.

[0113] Test Example 2

[0114] Test groups: Examples 1-3 and Comparative Example 1.

[0115] Test method:

[0116] (1) Half-wave potential: Polarization curves of Pt / CN-900, Pt / CN-950, Pt / CN-1000, and commercial Pt / C were measured in an oxygen-saturated 0.1 M KOH solution using a rotating disk electrode apparatus at a rotation rate of 1600 rpm / min.

[0117] (2) Attenuation degree: The attenuation was observed after 10,000 cycles using cyclic voltammetry.

[0118] Test results:

[0119] (1) Reference Figure 5 , it can be found that Pt / CN-900, Pt / CN-950, and Pt / CN-1000 have larger half-wave potentials than commercial Pt / C (the half-wave potential can qualitatively analyze the electrocatalytic oxygen reduction activity of the material; a larger half-wave potential indicates a better catalytic activity). Specific results are shown in Table 1. In particular, the half-wave potential of Pt / CN-900 is 0.90V, which is much larger than that of commercial Pt / C, indicating that these catalysts are more active than commercial Pt / C. This may be because the carbon substrate has a better conductivity at this temperature, which greatly improves their redox catalytic activity.

[0120] (2) Figure 6 The stability data for Pt / CN-900, Pt / CN-950, Pt / CN-1000, and commercial Pt / C are shown. The Pt / CN-900 nanomaterial prepared in Example 1 exhibits excellent stability, showing only slight attenuation after 10,000 cycles using cyclic voltammetry. However, significant attenuation was observed after 10,000 cycles for commercial Pt / C. Specific stability results are shown in Table 1.

[0121] Table 1 Half-wave potential results of Pt / C nanocatalysts obtained in Examples 1-3 and commercial Pt / C

[0122] Nanomaterials Pt / CN-900 Pt / CN-950 Pt / CN-1000 Commercial Pt / C Half-wave potential (V) 0.90 V 0.88 V 0.87 V 0.82 V <![CDATA[Degree of attenuation (△E 1 / 2 / mV)]]> 3 mV 22 mV 28 mV 55 mV

[0123] Test Example 3

[0124] Test groups: Example 1 and Comparative Example 1.

[0125] Test method: power density test.

[0126] Test results: Figure 7 The power density curves of the products of Example 1 and Comparative Example 1 measured when placed in a H2-O2 fuel cell show that Pt / CN-900 exhibits a greater maximum power density than commercial Pt / C.

[0127] Test Example 4

[0128] Test group: Comparative Example 2-3.

[0129] Test method: The samples of Comparative Example 2-3 were subjected to TEM analysis.

[0130] Test results: Figure 8 As shown, Figure 8 a is the TEM image of the sample of comparative example 2, Figure 8 b is the TEM image of the sample in comparative example 3. When the gas atmosphere is changed to argon, the particle size is larger and the distribution is uneven; when it is a hydrogen / argon mixed gas atmosphere, the Pt nanoparticle size is larger and the distribution is uneven, indicating that the rich nitrogen source of ammonia is crucial for regulating the size and distribution of Pt nanoparticles.

[0131] Test Example 5

[0132] Test group: Comparative Example 4.

[0133] Test method: The sample of Comparative Example 4 was subjected to TEM analysis.

[0134] Test results: Figure 9 As shown, Pt nanoparticles are unevenly distributed on the surface of the carbon substrate. When the electrocatalytic ORR performance is tested, it is found to be worse than that of commercial Pt / C, indicating that chloroplatinic acid as a platinum source can better coordinate strongly with the nitrogen source in the covalent organic framework, and plays a vital role in the formation of uniformly distributed Pt nanoparticles in this system.

[0135] Test Example 6

[0136] Test group: Comparative Example 5.

[0137] Test method: The sample of Comparative Example 5 was subjected to TEM.

[0138] Test results: Figure 10 As shown, the platinum nanoparticles on the carbon substrate are large and unevenly distributed. Furthermore, in electrocatalytic ORR performance testing, they exhibited poorer ORR activity than commercial Pt / C. This is likely due to the ordered porous structure of the covalent organic framework, which facilitates confinement and regulation of the size and distribution of Pt nanoparticles, preventing aggregation.

[0139] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, the embodiments should be regarded as illustrative and non-restrictive in all respects. The scope of the present invention is defined by the appended claims rather than the foregoing description, and all changes that come within the meaning and range of equivalents of the claims are intended to be included therein.

[0140] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A method for preparing a low-load Pt / C catalyst derived from a covalent organic framework, characterized in that: The steps include: S1: adding a platinum metal salt and a covalent organic framework to an ethanol solution, and after sufficient reflux and condensation, obtaining a covalent organic framework coordinated with platinum metal ions; S2: Pt / C catalyst with low loading is obtained by pyrolyzing the covalent organic framework coordinated with platinum metal ions obtained in step S1 in an atmosphere of argon and ammonia mixture, and cooling the mixture to obtain a derived low loading Pt / C catalyst; The covalent organic framework preparation method in step S1 is as follows: 15.00 mg (0.024 mmol) of tetrakis(4-formylphenyl)pyrene and 7.58 mg (0.048 mmol) of 1,4-phenyldiacetonitrile are selected as reaction monomers, added to a sealed glass tube containing 1 ml of a 1 / 5 volume mixed solution of mesitylene / 1,4-dioxane and 0.1 mL of 4 M NaOH, heated to 90°C, and reacted for 3 days to obtain a covalent organic framework; The covalent organic framework is an sp2 covalent organic framework.

2. The method for preparing a low-loaded Pt / C catalyst derived from a covalent organic framework according to claim 1, wherein: The mass ratio of the platinum metal salt to the covalent organic framework in step S1 is 0.1-0.

4.

3. The method for preparing a low-loaded Pt / C catalyst derived from a covalent organic framework according to claim 2, wherein: The platinum metal salt is chloroplatinic acid, sodium chloroplatinate, or potassium chloroplatinate.

4. The method for preparing a low-loaded Pt / C catalyst derived from a covalent organic framework according to claim 1, wherein: The pyrolysis treatment conditions in step S2 are: pyrolysis for 2-4 h, a temperature of 900-1000° C., and a heating rate of 2-5° C. / min.

5. The method for preparing a low-loaded Pt / C catalyst derived from a covalent organic framework according to claim 1, wherein: The volume ratio of argon gas to ammonia gas in step S2 is 10:

1.

6. A low-loaded Pt / C catalyst prepared by the method according to any one of claims 1 to 5, characterized in that: The mass fraction of platinum in the low-loaded Pt / C catalyst is 8%-12%.

7. Use of the low-loaded Pt / C catalyst according to claim 6 in cathode materials, fuel cells or fuel cell driving devices.

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