Material with noble metal loaded on carbon material and preparation method of material

Abstract

The invention provides a material with precious metal loaded on a carbon material and a preparation method of the material, and belongs to the technical field of electrochemical materials.The preparation method comprises the steps that S1, 0.6 g of modified hole carbon material is weighed and subjected to ultrasonic treatment in 400-500 mL of water for 1-1.2 h, and carbon dispersion liquid is obtained; s2, 0.07 g of potassium chloroplatinite is dissolved in 8-12 mL of ice water, ultrasonic treatment is conducted for 5 min, then the solution is added into the carbon dispersion liquid, ice bath stirring is conducted for 1-1.2 h, and composite liquid is obtained; s3, adding 0.12-0.16 g of sodium borohydride into 80-100 mL of ice water, stirring until the sodium borohydride is dissolved, adding the sodium borohydride into the complex liquid in an ice bath, and continuously stirring for 5-10 minutes to obtain a reaction liquid; and S4, carrying out suction filtration on the reaction liquid, washing the reaction liquid with deionized water for multiple times until the reaction liquid is neutral, and drying. And nano silicon dioxide particles are adhered in pore channels of the modified pore carbon material. When the prepared material with the noble metal loaded on the carbon material is used for the lithium-sulfur battery, the energy density (specific discharge capacity) and the cycle life (capacity retention ratio) of the lithium-sulfur battery can be effectively improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrochemical materials, and particularly relates to a material of noble metal supported on carbon material and a preparation method thereof. Background Art

[0002] Carbon materials, especially porous carbon materials, have high specific surface area, good electrical conductivity and excellent chemical stability, which make them ideal carriers for electrode materials. Noble metals, such as platinum (Pt), gold (Au), etc., have good electrocatalytic activity and can promote the progress of electrode reactions. In lithium-sulfur batteries, noble metal catalysts can effectively reduce the reaction barrier of sulfur reduction reaction (SRR), accelerate electrode reactions, and thus improve the electrochemical performance of the batteries. By loading noble metals onto carbon materials, the advantages of both can be combined to form a composite material with excellent electrochemical performance. This composite material not only retains the high specific surface area and electrical conductivity of carbon materials, but also introduces the catalytic activity of noble metals, thereby improving the overall performance of electrode materials.

[0003] Existing studies have shown that materials of noble metal supported on carbon materials as the positive electrode materials of lithium-sulfur batteries can improve the capacity utilization, cycle stability and rate performance of the batteries. On this basis, how to further improve the comprehensive performance of materials of noble metal supported on carbon materials is a topic worthy of in-depth study. Summary of the Invention

[0004] To solve the problems in the background art, the present invention provides a material of noble metal supported on carbon material and a preparation method thereof, ensuring that when the obtained material of noble metal supported on carbon material is used in lithium-sulfur batteries, the energy density (discharge specific capacity) and cycle life (capacity retention rate) of lithium-sulfur batteries can be effectively improved.

[0005] To achieve the above object, in the first aspect, a preparation method of a material of noble metal supported on carbon material of the present invention includes the following steps:

[0006] S1. Weigh 0.6 g of modified porous carbon material, and ultrasonically treat it in 400 - 500 mL of water for 1 - 1.2 h to obtain a carbon dispersion;

[0007] S2. Dissolve 0.07 g of potassium chloroplatinate in 8 - 12 mL of ice water, ultrasonically treat it for 5 min, and then add it to the carbon dispersion obtained in S1, and stir it in an ice bath for 1 - 1.2 h to obtain a composite solution;

[0008] S3. Add 0.12 - 0.16 g of sodium borohydride to 80 - 100 mL of ice water, stir until it is dissolved to obtain a dissolved solution, and then add the dissolved solution to the composite solution obtained in S2 under ice bath, and continue to stir for 5 - 10 min to obtain a reaction solution;

[0009] S4. Filter the reaction solution obtained in S3 by suction filtration, wash it with deionized water for multiple times until it is neutral, and then perform drying treatment to obtain the material of noble metal supported on carbon material.

[0010] There are nano-silica particles attached inside the pores of the modified porous carbon material.

[0011] Furthermore, the preparation method of the modified porous carbon material is as follows:

[0012] A1. Add 50 g of calcium carbonate, 2 g of stearic acid and 6 - 8 g of tetraethyl orthosilicate to 480 - 520 mL of ethanol solution, grind it with sand for 1 - 1.5 h, add 7 - 9 g of petroleum asphalt, and continue to grind it with sand for 1 - 1.5 h to obtain a composite slurry.

[0013] A2. Stir the composite slurry at 60 - 65 °C until it is evaporated to dryness to obtain a composite powder.

[0014] A3. Place the composite powder in a tube furnace and perform heat treatment in an inert gas atmosphere to obtain a pyrolyzed powder.

[0015] A4. React the pyrolyzed powder in a 2 - 2.2 mol / L hydrochloric acid solution at 80 °C for 20 - 24 h until no obvious bubbles are generated, rinse it with ethanol and deionized water for multiple times respectively, filter it by suction and dry it to obtain the modified porous carbon material.

[0016] Furthermore, in A1, the volume fraction of the ethanol solution is 45 - 60%.

[0017] Furthermore, in A3, the specific operation of the heat treatment is as follows:

[0018] First, heat it up to 290 - 310 °C at a rate of 2 - 3 °C / min and keep it warm for 2 - 2.5 h;

[0019] Then, heat it up to 520 - 550 °C at a rate of 1 - 2 °C / min and keep it warm for 1 - 1.2 h;

[0020] Finally, heat it up to 840 - 860 °C at a rate of 3 - 5 °C / min and keep it warm for 1.8 - 2 h.

[0021] Furthermore, in S1 and S2, the ultrasonic power is 100 - 120 W.

[0022] Furthermore, in S2 and S3, the stirring speed is 240 - 300 r / min.

[0023] Furthermore, in S3, the adding speed of the dissolution solution is 8 - 10 mL / min.

[0024] Furthermore, in S4, the specific operation of the drying treatment is: dry it at 50 - 55 °C for 3 - 4 h.

[0025] In a second aspect, the present invention provides a material of noble metal supported on carbon material, which is prepared by the above preparation method.

[0026] This application has the following beneficial effects:

[0027] 1. In the preparation of the modified mesoporous carbon material of the present invention, the higher the heat treatment temperature, the more intense the pyrolysis reaction, and the larger the pore diameter of the formed pores tends to be. And tetraethyl orthosilicate as the silicon source, after being mixed with calcium carbonate, stearic acid and petroleum asphalt and then subjected to sand grinding treatment, makes tetraethyl orthosilicate fully mixed with other components; in the subsequent high-temperature heat treatment (the three heat preservation temperatures during the heat treatment process are 300 °C, 530 °C and 850 °C in sequence), the silicon dioxide nanoparticles generated by the decomposition of tetraethyl orthosilicate can better adhere to the surface and inside the pore channels of the mesoporous carbon material, thereby modifying the morphology of the mesoporous channels, which can not only improve the loading and dispersion uniformity of subsequent noble metal particles, but also avoid the excessive mobility of noble metal particles in the pore channels and affect the catalytic stability, and further synergistically improve the performance of the finally prepared material of noble metal supported on carbon material.

[0028] 2. Sodium borohydride in the present invention is a strong reducing agent, which can effectively reduce platinum ions in potassium chloroplatinate to zero-valent metal atoms or nanoparticles in the reaction solution, and make them better deposited / loaded on the surface and inside the pore channels of the modified mesoporous carbon material. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A comparison trend chart of the first discharge specific capacity test data of the materials of noble metal supported on carbon material prepared in Examples 1-5 and Comparative Examples 1-5 in the test examples of the present invention for lithium-sulfur batteries;

[0030] Figure 2 A comparison trend chart of the capacity retention rate test data of the materials of noble metal supported on carbon material prepared in Examples 1-5 and Comparative Examples 1-5 in the test examples of the present invention for lithium-sulfur batteries after 300 cycles of the battery. DETAILED DESCRIPTION OF THE INVENTION

[0031] The following further elaborates on this application with reference to examples.

[0032] The raw materials in the examples and comparative examples of this application are all ordinary commercially available products unless otherwise specified.

[0033] Example 1: (1) Preparation of modified mesoporous carbon material, and its preparation method is as follows:

[0034] A1. Add 50 g of calcium carbonate, 2 g of stearic acid and 7 g of tetraethyl orthosilicate to 500 mL of an ethanol solution with a volume fraction of 50%, sand grind for 1.2 h, add 8 g of petroleum asphalt, and continue sand grinding for 1.2 h to obtain a composite slurry.

[0035] A2. Stir the composite slurry at 62 °C until it is evaporated to dryness to obtain a composite powder.

[0036] A3. Place the composite powder in a tubular furnace and perform heat treatment in an inert gas (argon) atmosphere. The specific operation of the heat treatment is as follows:

[0037] First, heat it to 300 °C at a rate of 2 °C / min and hold for 2 h;

[0038] Then, heat it to 530 °C at a rate of 2 °C / min and hold for 1 h;

[0039] Finally, heat it to 850 °C at a rate of 4 °C / min and hold for 2 h.

[0040] After the heat treatment is completed, a pyrolyzed powder is obtained.

[0041] A4. React the pyrolyzed powder in a 2 mol / L hydrochloric acid solution at 80 °C for 22 h until no obvious bubbles are generated. Rinse it three times with ethanol and deionized water respectively, filter it by suction and dry it to obtain the modified porous carbon material.

[0042] (2) Prepare a material of carbon material supported with noble metal. The preparation method is as follows:

[0043] S1. Weigh 0.6 g of the modified porous carbon material and ultrasonicate it in 450 mL of water for 1.1 h to obtain a carbon dispersion. The ultrasonic power is 110 W in all cases.

[0044] S2. Dissolve 0.07 g of potassium chloroplatinate in 10 mL of ice water. After ultrasonication for 5 min, add it to the carbon dispersion obtained in S1 and stir in an ice bath for 1 h to obtain a composite solution. The ultrasonic power is 110 W in all cases. The stirring speed is 280 r / min in all cases.

[0045] S3. Add 0.14 g of sodium borohydride to 90 mL of ice water and stir until it is dissolved to obtain a dissolved solution. Then, add the dissolved solution to the composite solution obtained in S2 at a rate of 9 mL / min in an ice bath and continue stirring for 8 min to obtain a reaction solution. The stirring speed is 280 r / min in all cases.

[0046] S4. Filter the reaction solution obtained in S3 by suction, wash it three times with deionized water until it is neutral, and then place it in a drying oven and dry it at a temperature of 52 °C for 3.5 h to obtain the material of carbon material supported with noble metal.

[0047] Example 2: The difference between this example and Example 1 is that: (1) Prepare the modified porous carbon material. The preparation method is as follows:

[0048] A1. Add 50 g of calcium carbonate, 2 g of stearic acid, and 6 g of tetraethyl orthosilicate to 480 mL of an ethanol solution with a volume fraction of 45%, grind for 1 h, add 7 g of petroleum asphalt, and continue to grind for 1 h to obtain a composite slurry.

[0049] A2. Stir the composite slurry at 60 °C until it is evaporated to dryness to obtain a composite powder.

[0050] A3. Place the composite powder in a tube furnace and perform heat treatment under an inert gas atmosphere. The specific operation of the heat treatment is as follows:

[0051] First, heat it at a rate of 2 °C / min to 290 °C and hold for 2 h;

[0052] Then, heat it at a rate of 2 °C / min to 520 °C and hold for 1 h;

[0053] Finally, heat it at a rate of 4 °C / min to 840 °C and hold for 1.8 h.

[0054] After the heat treatment is completed, a pyrolyzed powder is obtained.

[0055] A4. React the pyrolyzed powder in a 2 mol / L hydrochloric acid solution at 80 °C for 22.7 h until no obvious bubbles are generated, rinse it three times with ethanol and deionized water respectively, and filter and dry it to obtain the modified porous carbon material.

[0056] Example 3: The difference between this example and Example 1 is: (1) Prepare the modified porous carbon material, and its preparation method is as follows:

[0057] A1. Add 50 g of calcium carbonate, 2 g of stearic acid, and 8 g of tetraethyl orthosilicate to 520 mL of an ethanol solution with a volume fraction of 60%, grind for 1.5 h, add 9 g of petroleum asphalt, and continue to grind for 1.5 h to obtain a composite slurry.

[0058] A2. Stir the composite slurry at 65 °C until it is evaporated to dryness to obtain a composite powder.

[0059] A3. Place the composite powder in a tube furnace and perform heat treatment under an inert gas atmosphere. The specific operation of the heat treatment is as follows:

[0060] First, heat it at a rate of 2 °C / min to 310 °C and hold for 2 h;

[0061] Then, heat it at a rate of 2 °C / min to 550 °C and hold for 1 h;

[0062] Finally, heat it at a rate of 4 °C / min to 860 °C and hold for 2 h.

[0063] After the heat treatment is completed, a pyrolyzed powder is obtained.

[0064] A4. React the pyrolysis powder in a 2.2 mol / L hydrochloric acid solution at 80 °C for 20.3 h until no obvious bubbles are generated. Rinse it three times with ethanol and deionized water respectively, then filter by suction and dry to obtain the modified porous carbon material.

[0065] Example 4: The difference between this example and Example 1 lies in: (2) Prepare the material of carbon material loaded with noble metal, and its preparation method is as follows:

[0066] S1. Weigh 0.6 g of the modified porous carbon material and ultrasonicate it in 400 mL of water for 1 h to obtain a carbon dispersion. The ultrasonic power is 100 W for all.

[0067] S2. Dissolve 0.07 g of potassium chloroplatinate in 8 mL of ice water. After ultrasonication for 5 min, add it to the carbon dispersion obtained in S1, and stir in an ice bath for 1 h to obtain a composite solution. The ultrasonic power is 100 W for all. The stirring speed is 240 r / min for all.

[0068] S3. Add 0.12 g of sodium borohydride to 80 mL of ice water and stir until dissolved to obtain a dissolved solution. Then, add the dissolved solution to the composite solution obtained in S2 at a speed of 8 mL / min in an ice bath and continue to stir for 5 min to obtain a reaction solution. The stirring speed is 240 r / min for all.

[0069] S4. Filter the reaction solution obtained in S3 by suction, wash it with deionized water for multiple times until neutral, then place it in an oven and dry it at 50 °C for 3 h to obtain the material of carbon material loaded with noble metal.

[0070] Example 5: The difference between this example and Example 1 lies in: (2) Prepare the material of carbon material loaded with noble metal, and its preparation method is as follows:

[0071] S1. Weigh 0.6 g of the modified porous carbon material and ultrasonicate it in 500 mL of water for 1.2 h to obtain a carbon dispersion. The ultrasonic power is 120 W for all.

[0072] S2. Dissolve 0.07 g of potassium chloroplatinate in 12 mL of ice water. After ultrasonication for 5 min, add it to the carbon dispersion obtained in S1, and stir in an ice bath for 1.2 h to obtain a composite solution. The ultrasonic power is 120 W for all. The stirring speed is 300 r / min for all.

[0073] S3. Add 0.16 g of sodium borohydride to 100 mL of ice water and stir until dissolved to obtain a dissolved solution. Then, add the dissolved solution to the composite solution obtained in S2 at a speed of 10 mL / min in an ice bath and continue to stir for 10 min to obtain a reaction solution. The stirring speed is 300 r / min for all.

[0074] S4. Perform suction filtration on the reaction solution obtained in S3. After washing it with deionized water multiple times until it is neutral, place it in a drying oven and dry it at 55 °C for 4 h to obtain the material of noble metal supported on carbon material.

[0075] Comparative Example 1: The difference between this comparative example and Example 1 lies in that in the preparation of the modified porous carbon material, tetraethyl orthosilicate is deleted; and the three heat preservation temperatures in the heat treatment process are 300 °C, 500 °C, and 800 °C in sequence.

[0076] Specifically, to prepare the modified porous carbon material, the preparation method is as follows:

[0077] A1. Add 50 g of calcium carbonate and 2 g of stearic acid to 500 mL of an ethanol solution with a volume fraction of 50%, grind for 1.2 h, add 8 g of petroleum asphalt, and continue to grind for 1.2 h to obtain a composite slurry.

[0078] A2. Stir the composite slurry at 62 °C until it is evaporated to dryness to obtain a composite powder.

[0079] A3. Place the composite powder in a tubular furnace and perform heat treatment in an inert gas (argon) atmosphere. The specific operation of the heat treatment is as follows:

[0080] First, heat it up to 300 °C at a rate of 2 °C / min and keep it warm for 2 h;

[0081] Then, heat it up to 500 °C at a rate of 2 °C / min and keep it warm for 1 h;

[0082] Finally, heat it up to 800 °C at a rate of 4 °C / min and keep it warm for 2 h.

[0083] After the heat treatment is completed, a pyrolyzed powder is obtained.

[0084] A4. React the pyrolyzed powder in a 2 mol / L hydrochloric acid solution at 80 °C for 22 h, rinse it three times with ethanol and deionized water respectively, perform suction filtration and drying to obtain the modified porous carbon material.

[0085] Comparative Example 2: The difference between this comparative example and Example 1 lies in that in the preparation of the modified porous carbon material, tetraethyl orthosilicate is deleted; and the three heat preservation temperatures in the heat treatment process are 300 °C, 460 °C, and 760 °C in sequence.

[0086] Specifically, to prepare the modified porous carbon material, the preparation method is as follows:

[0087] A1. Add 50 g of calcium carbonate and 2 g of stearic acid to 500 mL of an ethanol solution with a volume fraction of 50%, grind for 1.2 h, add 8 g of petroleum asphalt, and continue to grind for 1.2 h to obtain a composite slurry.

[0088] A2. Stir the composite slurry at 62 °C until it is evaporated to dryness to obtain a composite powder.

[0089] A3. Place the composite powder in a tubular furnace and perform heat treatment under an inert gas (argon) atmosphere. The specific operation of the heat treatment is as follows:

[0090] First, heat it to 300 °C at a rate of 2 °C / min and hold for 2 h;

[0091] Then, heat it to 460 °C at a rate of 2 °C / min and hold for 1 h;

[0092] Finally, heat it to 760 °C at a rate of 4 °C / min and hold for 2 h.

[0093] After the heat treatment is completed, pyrolyzed powder is obtained.

[0094] A4. React the pyrolyzed powder in a 2 mol / L hydrochloric acid solution at 80 °C for 22 h, rinse it three times with ethanol and deionized water respectively, and filter and dry it to obtain the modified porous carbon material.

[0095] Comparative Example 3: The difference between this comparative example and Example 1 is that in the preparation of the modified porous carbon material, tetraethyl orthosilicate is deleted.

[0096] Specifically, to prepare the modified porous carbon material, the preparation method is as follows:

[0097] A1. Add 50 g of calcium carbonate and 2 g of stearic acid to 500 mL of an ethanol solution with a volume fraction of 50%, grind it for 1.2 h, add 8 g of petroleum asphalt, and continue to grind it for 1.2 h to obtain a composite slurry.

[0098] A2. Stir the composite slurry at 62 °C until it is evaporated to dryness to obtain a composite powder.

[0099] A3. Place the composite powder in a tubular furnace and perform heat treatment under an inert gas (argon) atmosphere. The specific operation of the heat treatment is as follows:

[0100] First, heat it to 300 °C at a rate of 2 °C / min and hold for 2 h;

[0101] Then, heat it to 530 °C at a rate of 2 °C / min and hold for 1 h;

[0102] Finally, heat it to 850 °C at a rate of 4 °C / min and hold for 2 h.

[0103] After the heat treatment is completed, pyrolyzed powder is obtained.

[0104] A4. React the pyrolyzed powder in a 2 mol / L hydrochloric acid solution at 80 °C for 22 h, rinse it three times with ethanol and deionized water respectively, and filter and dry it to obtain the modified porous carbon material.

[0105] Comparative Example 4: The difference between this comparative example and Example 1 is that the three heat preservation temperatures during the heat treatment process are 300 °C, 500 °C, and 800 °C in sequence.

[0106] Specifically, a modified porous carbon material is prepared, and its preparation method is as follows:

[0107] A1. Add 50 g of calcium carbonate, 2 g of stearic acid, and 7 g of tetraethyl orthosilicate to 500 mL of an ethanol solution with a volume fraction of 50%, grind for 1.2 h, add 8 g of petroleum asphalt, and continue to grind for 1.2 h to obtain a composite slurry.

[0108] A2. Stir the composite slurry at 62 °C until it is evaporated to dryness to obtain a composite powder.

[0109] A3. Place the composite powder in a tube furnace and conduct heat treatment in an inert gas (argon) atmosphere. The specific operation of the heat treatment is as follows:

[0110] First, heat up to 300 °C at a rate of 2 °C / min and keep it warm for 2 h;

[0111] Then, heat up to 500 °C at a rate of 2 °C / min and keep it warm for 1 h;

[0112] Finally, heat up to 800 °C at a rate of 4 °C / min and keep it warm for 2 h.

[0113] After the heat treatment is completed, a pyrolysis powder is obtained.

[0114] A4. React the pyrolysis powder in a 2 mol / L hydrochloric acid solution at 80 °C for 22 h, rinse it three times with ethanol and deionized water respectively, and filter and dry it to obtain the modified porous carbon material.

[0115] Comparative Example 5: The difference between this comparative example and Example 1 is that the three heat preservation temperatures during the heat treatment process are 300 °C, 460 °C, and 760 °C in sequence.

[0116] Specifically, a modified porous carbon material is prepared, and its preparation method is as follows:

[0117] A1. Add 50 g of calcium carbonate, 2 g of stearic acid, and 7 g of tetraethyl orthosilicate to 500 mL of an ethanol solution with a volume fraction of 50%, grind for 1.2 h, add 8 g of petroleum asphalt, and continue to grind for 1.2 h to obtain a composite slurry.

[0118] A2. Stir the composite slurry at 62 °C until it is evaporated to dryness to obtain a composite powder.

[0119] A3. Place the composite powder in a tube furnace and conduct heat treatment in an inert gas (argon) atmosphere. The specific operation of the heat treatment is as follows:

[0120] First, heat up to 300 °C at a rate of 2 °C / min and keep it warm for 2 h;

[0121] Then, heat it up to 460 °C at a rate of 2 °C / min and hold for 1 h;

[0122] Finally, heat it up to 760 °C at a rate of 4 °C / min and hold for 2 h.

[0123] After the heat treatment, pyrolysis powder is obtained.

[0124] A4. React the pyrolysis powder in a 2 mol / L hydrochloric acid solution at 80 °C for 22 h, rinse it three times with ethanol and deionized water respectively, filter it by suction and dry it to obtain the modified porous carbon material.

[0125] Test example: Test object: Materials of carbon materials loaded with noble metals prepared in Examples 1 - 5 and Comparative Examples 1 - 5.

[0126] Test methods and contents: Vacuum dry each test object (carbon material loaded with noble metal) at 120 °C for 3 h, vacuum dry high-purity sulfur at 50 °C for 2 h, weigh the dried test object and sulfur according to the mass ratio of sulfur content of 60%, grind them until there is no obvious granular feeling, and then add the uniformly mixed materials into the inner liner of the hydrothermal reactor in the glove box. After changing the air for 10 min, ensure that the inner liner of the hydrothermal reactor is filled with inert gas, and then seal the reactor and take it out. Place the hydrothermal reactor in a blast drying oven to react for 24 h at a reaction temperature of 155 °C, cool it to room temperature to obtain the sulfur-doped carbon material loaded with noble metal.

[0127] Weigh the sulfur-doped carbon material loaded with noble metal, conductive agent (conductive carbon black Super P purchased from Tianjin Yiborui Chemical Co., Ltd.) and water-based binder (purity 15 ± 0.2%, purchased from Zhengzhou Alpha Chemical Co., Ltd.), and the mass ratio of the three is 8:1:1. After grinding for 30 min, transfer it to a centrifuge tube, add zirconia balls, then drop in deionized water, take out the centrifuge tube after stirring twice in a homogenizer, add anhydrous ethanol to defoam, stir once again, and then evenly coat it on the carbon-coated aluminum foil to make the loading amount 1 ± 0.2 mg / cm 2 . Let it stand overnight at room temperature, and then vacuum dry it at 50 °C in an oven for 12 h to prepare the electrode sheet. Assemble the electrode sheet into a battery and test the cycle performance at a current density of 0.2C, including the initial discharge specific capacity and the capacity retention rate after 300 cycles of the battery.

[0128] Test results: See Table 1.

[0129] Table 1. Test data of test examples

[0130]

[0131] Result analysis: Analyze Examples 1 - 5 and combine the data in Table 1 and Figure 1 - Figure 2It can be seen that the first discharge specific capacity of the carbon material-supported noble metal material prepared by the present invention for lithium-sulfur batteries is as high as over 765.7 mAh / g, and the capacity retention rate after 300 cycles is higher than 63.4%.

[0132] Analyze Example 1 and Comparative Examples 1-5 and combine the data in Table 1 and Figure 1 - Figure 2 , it can be known from the comparison of Comparative Example 1, Comparative Example 2 and Comparative Example 3 that as the temperature increases during the heat treatment process (temperature of Comparative Example 2 < temperature of Comparative Example 1 < temperature of Comparative Example 3), the performance of the carbon material-supported noble metal material prepared first increases and then decreases. Among the three, the performance of the carbon material-supported noble metal material prepared by Comparative Example 1 (the three heat preservation temperatures during the heat treatment process are 300 °C, 500 °C and 800 °C in sequence) is the best.

[0133] This is because the higher the temperature of the heat treatment, the more intense the pyrolysis reaction, and the more the pore diameter formed tends to increase. When the temperature increases from Comparative Example 2 (the three heat preservation temperatures during the heat treatment process are 300 °C, 460 °C and 760 °C in sequence) to Comparative Example 1 (the three heat preservation temperatures during the heat treatment process are 300 °C, 500 °C and 800 °C in sequence), the pore diameter increases to a more appropriate size, which is beneficial to improving the performance of the finally prepared carbon material-supported noble metal material. When the temperature increases from Comparative Example 1 (the three heat preservation temperatures during the heat treatment process are 300 °C, 500 °C and 800 °C in sequence) to Example 1 (the three heat preservation temperatures during the heat treatment process are 300 °C, 530 °C and 850 °C in sequence), too large pore diameters are formed, which may not only lead to uneven loading of noble metal particles / high local loading, but also lead to too strong mobility of noble metal particles in the pores, thus having a negative impact on the performance of the finally prepared carbon material-supported noble metal material.

[0134] Combined with the comparison of Comparative Example 4, Comparative Example 5 and Example 1, it can be known that compared with Comparative Example 1, tetraethyl orthosilicate is added in the preparation of the modified porous carbon material in Comparative Example 4, and as a result, the performance of the carbon material-supported noble metal material prepared decreases; compared with Comparative Example 2, tetraethyl orthosilicate is also added in the preparation of the modified porous carbon material in Comparative Example 5, and as a result, the performance of the carbon material-supported noble metal material prepared also decreases. It shows that when the three heat preservation temperatures during the heat treatment process are 300 °C, 500 °C and 800 °C in sequence, and the three heat preservation temperatures during the heat treatment process are 300 °C, 460 °C and 760 °C in sequence during the preparation of the modified porous carbon material, adding tetraethyl orthosilicate will cause the performance of the finally prepared carbon material-supported noble metal material to decrease.

[0135] Compared with Comparative Example 3, tetraethyl orthosilicate was added in the preparation of the modified porous carbon material in Example 1, and as a result, the performance of the material with noble metal supported on the carbon material was improved, and the performance was better than that of Comparative Example 1. It shows that when tetraethyl orthosilicate is added during the preparation of the modified porous carbon material and the three heat preservation temperatures during the heat treatment process are 300 °C, 530 °C and 850 °C in sequence, the performance of the finally prepared material with noble metal supported on the carbon material can be improved. It shows that a synergistic effect can be generated between this temperature condition (the three heat preservation temperatures during the heat treatment process are 300 °C, 530 °C and 850 °C in sequence) and the added tetraethyl orthosilicate, and the performance of the finally prepared material with noble metal supported on the carbon material is synergistically improved.

[0136] In addition, it should be noted that for each specific technical feature described in the above specific embodiments, without conflict, they can be combined in any suitable way. To avoid unnecessary repetition, the present invention will not separately describe various possible combination methods.

[0137] In addition, any combination can be made between various different embodiments of the present invention, as long as it does not violate the idea of the present invention, it should also be regarded as the content disclosed by the present invention.

Claims

1. A method for preparing a carbon material loaded with precious metals, characterized in that: The steps include: S1, weigh 0.6 g of the modified porous carbon material, and ultrasonicate it in 400-500 mL of water for 1-1.2 h to obtain a carbon dispersion; S2, dissolve 0.07 g of potassium chloroplatinite in 8-12 mL of ice water, ultrasonicate for 5 min, add to the carbon dispersion obtained in S1, stir in an ice bath for 1-1.2 h to obtain a composite solution; S3, adding 0.12-0.16 g of sodium borohydride to 80-100 mL of ice water, stirring until dissolved to obtain a solution, then adding the solution to the composite solution obtained in S2 under an ice bath, and continuing to stir for 5-10 minutes to obtain a reaction solution; S4, filtering the reaction solution obtained in S3, washing with deionized water for multiple times until it is neutral, and drying to obtain the carbon material loaded with precious metals; Nano silicon dioxide particles are attached in the pores of the modified porous carbon material.

2. The method for preparing a carbon material loaded with noble metals according to claim 1, characterized in that: The preparation method of the modified porous carbon material is as follows: A1. Add 50 g of calcium carbonate, 2 g of stearic acid and 6-8 g of tetraethyl orthosilicate to 480-520 mL of ethanol solution, sand grind for 1-1.5 h, add 7-9 g of petroleum asphalt, and continue sand grinding for 1-1.5 h to obtain a composite slurry; A2, stirring the composite slurry at 60-65°C until it is evaporated to dryness to obtain a composite powder; A3, placing the composite powder in a tube furnace, and performing heat treatment under an inert gas atmosphere to obtain a pyrolysis powder; A4. The pyrolysis powder is reacted in a 2-2.2 mol / L hydrochloric acid solution at 80°C for 20-24 hours, washed with ethanol and deionized water for multiple times, filtered and dried to obtain a modified porous carbon material.

3. The method for preparing a carbon material loaded with noble metals according to claim 2, characterized in that: In A1, the volume fraction of the ethanol solution is 45-60%.

4. The method for preparing a carbon material loaded with noble metals according to claim 2, characterized in that: In A3, the specific operation of heat treatment is: First, heat to 290-310℃ at a rate of 2-3℃ / min and keep warm for 2-2.5h; Then increase the temperature to 520-550℃ at a rate of 1-2℃ / min and keep warm for 1-1.2h; Finally, the temperature was raised to 840-860°C at a rate of 3-5°C / min and kept at this temperature for 1.8-2h.

5. The method for preparing a carbon material loaded with noble metals according to claim 1, characterized in that: In S1 and S2, the ultrasonic power was 100-120W.

6. The method for preparing a carbon material loaded with noble metals according to claim 1, characterized in that: In S2 and S3, the stirring speed is 240-300 r / min.

7. The method for preparing a carbon material loaded with noble metals according to claim 1, characterized in that: In S3, the dissolving solution is added at a rate of 8-10 mL / min.

8. The method for preparing a carbon material loaded with noble metals according to claim 1, characterized in that: In S4, the specific operation of the drying treatment is: drying at 50-55° C. for 3-4 hours.

9. A carbon material loaded with precious metals, characterized in that: The method is prepared according to any one of claims 1 to 8.

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