Oxygen-enriched microporous carbon-loaded platinum catalyst as well as preparation method and application thereof

Abstract

The invention provides an oxygen-enriched microporous carbon loaded platinum catalyst and a preparation method and application thereof, and relates to the technical field of fuel cells, the catalyst comprises an oxygen-enriched microporous carbon carrier and platinum nanoparticles loaded on the oxygen-enriched microporous carbon carrier, the oxygen-enriched microporous carbon carrier contains a microporous structure, and the platinum nanoparticles are loaded on the oxygen-enriched microporous carbon carrier. Hydrophilic oxygen-containing functional groups are attached to the surfaces of the platinum nanoparticles, and the particle size of the platinum nanoparticles is 3-5 nm. Water can be effectively stored in micropores by utilizing the microporous structure of oxygen-enriched microporous carbon and hydrophilic oxygen-containing functional groups attached to the surface of the oxygen-enriched microporous carbon, and the platinum nanoparticles with larger particle sizes are combined, so that the water retention capacity of the membrane electrode is improved, the utilization rate of the platinum nanoparticles is also improved, the catalytic activity of the catalyst is also improved, and the preparation method is suitable for industrial production. The catalyst still shows excellent output performance in a fuel cell test under a low-humidity working condition, is suitable for large-scale industrial production, and has wide application potential in an air-cooled fuel cell stack.

Description

Technical Field

[0001] This invention relates to the field of fuel cell technology, and in particular to an oxygen-enriched microporous carbon-supported platinum catalyst, its preparation method, and its application. Background Technology

[0002] A proton exchange membrane fuel cell (PEMFC) is an advanced energy conversion device that directly converts chemical energy into electrical energy. It has many advantages, such as high energy conversion efficiency, strong adaptability to low-temperature operating environments, clean and pollution-free operation, and rapid start-up.

[0003] The core component of a PEMFC is the membrane electrode assembly (MEA), which can be divided into water-cooled and air-cooled types depending on the temperature control method. To improve heat dissipation and heat exchange efficiency in air-cooled PEMFCs, a larger airflow is often required. This leads to moisture in the MEA being easily carried away by the air, resulting in reduced membrane wettability and ultimately adversely affecting the battery's output performance. However, since the MEA is the core component of a PEMFC, maintaining proper wetting of the MEA under low humidity conditions (RH < 40%) is crucial and key to ensuring efficient proton conduction.

[0004] In existing technologies, methods to improve the water retention capacity of membrane electrodes under low humidity conditions mainly focus on the self-humidifying design of proton exchange membranes or the multilayer structure design of membrane electrodes. These methods suffer from problems such as poor conductivity of the introduced materials, complex processes for improvement schemes, and high costs, hindering industrial-scale application. The materials used in membrane electrode fabrication mainly include electrolyte membranes, catalysts, and conductive materials. Addressing the water retention problem of membrane electrodes under low humidity conditions directly at the level of platinum-based catalysts can simplify membrane electrode design to the greatest extent possible, making it suitable for industrial application.

[0005] Currently, common platinum-based catalysts are mainly carbon supports loaded with platinum nanoparticles. Traditional carbon supports have strong hydrophobic surfaces, which cannot effectively maintain the humidity of the reaction interface, resulting in a decrease in the water retention capacity of the membrane electrode and a weakening of proton transport performance. Furthermore, due to the long oxygen transport path, the platinum nanoparticles grown in micropores are difficult to utilize, resulting in low utilization rate of platinum nanoparticles and a decrease in the output performance of PEMFCs.

[0006] Therefore, this invention is proposed. Summary of the Invention

[0007] This invention provides an oxygen-enriched microporous carbon-supported platinum catalyst, its preparation method, and its application, in order to solve the defect in the prior art where conventional platinum catalysts are difficult to effectively increase the water retention capacity of membrane electrodes under low humidity conditions.

[0008] This invention provides an oxygen-enriched microporous carbon-supported platinum catalyst, which includes an oxygen-enriched microporous carbon support and platinum nanoparticles supported on the oxygen-enriched microporous carbon support. The oxygen-enriched microporous carbon support has a microporous structure and oxygen-containing functional groups are connected to its surface. The platinum nanoparticles have a particle size of 3-5 nm.

[0009] The oxygen-containing functional group is a hydrophilic functional group, preferably one or more of carboxyl, hydroxyl and carbonyl groups; the oxygen-containing functional group can form covalent bonds with carbon atoms in the oxygen-rich microporous carbon support, and is connected to the surface of the oxygen-rich microporous carbon support in the form of covalent bonds, rather than in the bulk phase.

[0010] The catalyst of this invention employs an oxygen-rich microporous carbon as a support and loads platinum nanoparticles onto this support. The oxygen-rich microporous carbon can effectively store water discharged from the proton exchange membrane toward the cathode diffusion layer within the micropores of the oxygen-rich microporous carbon support. Furthermore, the hydrophilic oxygen-containing functional groups attached to the surface of the oxygen-rich microporous carbon support can delay the discharge of water from the micropores, achieving the effect of water retention and thus improving the water retention capacity of the membrane electrode and enhancing the output performance of the PEMFC.

[0011] When the particle size of platinum nanoparticles is 3-5 nm, the phenomenon that small-sized platinum nanoparticles cannot be effectively utilized due to being loaded within the micropores of oxygen-rich microporous carbon supports can be effectively avoided, thus improving the utilization rate of platinum nanoparticles and thereby enhancing the output performance of PEMFCs. However, when the particle size of platinum nanoparticles is greater than 5 nm, the specific surface area of ​​platinum nanoparticles decreases, their distribution on the support becomes uneven, and their catalytic activity decreases.

[0012] According to the present invention, an oxygen-enriched microporous carbon-supported platinum catalyst is provided, wherein the volume ratio of micropores in the oxygen-enriched microporous carbon support is 50-70%. When the volume ratio of micropores in the oxygen-enriched microporous carbon support is less than 50%, the water content stored in the micropores is too low, which is not conducive to improving the water retention performance of the membrane electrode. When the volume ratio of micropores is 50-70%, the water produced by the reaction can be stored in the micropores, effectively improving the water retention capacity of the membrane electrode. When the volume ratio of micropores is greater than 70%, a large amount of water will be stored in the micropores, which can easily cause micropore blockage, hinder oxygen transport, reduce the efficiency of oxygen reduction reaction, and decrease the output performance of PEMFC.

[0013] According to the present invention, an oxygen-enriched microporous carbon-supported platinum catalyst is provided, wherein the oxygen content on the surface of the oxygen-enriched microporous carbon support is 10-20%.

[0014] According to the present invention, an oxygen-enriched microporous carbon-supported platinum catalyst is provided, wherein the mass content of platinum in the oxygen-enriched microporous carbon-supported platinum catalyst is 30wt%-70wt%.

[0015] This invention also provides a method for preparing an oxygen-enriched microporous carbon-supported platinum catalyst as described above, comprising the following steps: Step 1) Constructing microporous carbon materials: The carbon precursor and activator are mixed at a mass ratio of 1:3-1:5 and then activated at high temperature. After being kept at a constant temperature under an inert atmosphere, the microporous carbon materials are obtained after cooling. Step 2) Preparation of oxygen-enriched microporous carbon support: The microporous carbon material obtained in step 1) is washed until neutral and then immersed in concentrated nitric acid solution for acid oxidation treatment. After filtration and drying, the oxygen-enriched microporous carbon support is obtained. Step 3) Preparation of platinum nanoparticles: Weigh platinum precursor and surfactant and dissolve them in solvent. Add pH adjuster to adjust pH to 8-12. After reflux heating under argon atmosphere, centrifuge to obtain platinum nanoparticles. Preferably, the solvent is any one of ethylene glycol, formic acid and sodium borohydride aqueous solution. Step 4) Catalyst preparation: The oxygen-rich microporous carbon support obtained in step 2) and the platinum nanoparticles obtained in step 3) are mixed under ultrasonic conditions, washed by centrifugation and then vacuum dried.

[0016] In preparing the oxygen-enriched microporous carbon support, the carbon precursor and activator are first activated at high temperature in an inert atmosphere to construct a microporous structure. Then, after cleaning the obtained microporous carbon material, surface functionalization modification is performed by acid oxidation in a nitric acid system. This connects hydrophilic oxygen-containing functional groups to the surface of the oxygen-enriched microporous carbon support, effectively increasing the content of hydrophilic oxygen-containing functional groups such as carboxyl, hydroxyl, and carbonyl groups on the surface of the oxygen-enriched microporous carbon support, improving the hydrophilicity of the support, delaying the process of water expulsion from the micropores, and improving the water retention capacity of the membrane electrode.

[0017] In preparing platinum nanoparticles, this invention employs a reduction method, where a platinum precursor is reacted with a surfactant and a pH adjuster under argon protection conditions via reflux heating. The combined action of the surfactant and pH adjuster effectively controls the particle size of the platinum nanoparticles, resulting in a particle size of 3-5 nm, thereby improving the utilization rate of the platinum nanoparticles.

[0018] In step 4) of this invention, platinum nanoparticles are uniformly dispersed and loaded onto an oxygen-rich microporous carbon support by ultrasonic treatment, and the size is uniform. The platinum nanoparticles with larger particle size loaded on the oxygen-rich microporous carbon support can not only improve the catalytic activity of the catalyst, but also improve the water retention of the catalyst under low humidity conditions, thereby improving the water retention capacity of the membrane electrode and having better output performance.

[0019] According to the preparation method of the oxygen-enriched microporous carbon-supported platinum catalyst provided by the present invention, in step 1), the heating program of the high-temperature activation treatment is to heat to 800-1000℃ at a heating rate of 5-8℃ / min, and the holding time is 1-120min.

[0020] Preferably, the activator is at least one of potassium hydroxide and sodium hydroxide.

[0021] Preferably, the mass ratio of the carbon precursor to the activator is 1:4, and the high-temperature activation treatment is performed by heating to 900°C at a heating rate of 5-8°C / min and holding for 120 min.

[0022] According to the present invention, a method for preparing an oxygen-enriched microporous carbon-supported platinum catalyst is provided, wherein the carbon precursor is any one of Vulcan XC72R, Ketjen Black EC300J, Ketjen Black ECP600JD and Black Pearls 2000, and the activator is at least one of potassium hydroxide and sodium hydroxide.

[0023] According to the present invention, a method for preparing an oxygen-enriched microporous carbon-supported platinum catalyst is provided, wherein the acid oxidation treatment temperature is 80-120℃ and the acid oxidation treatment time is 2-6 h.

[0024] Preferably, the acid oxidation treatment is performed at a temperature of 100°C for 4 hours.

[0025] According to the present invention, a method for preparing an oxygen-enriched microporous carbon-supported platinum catalyst is provided, wherein the concentration of the concentrated nitric acid is 1-6 mol / L.

[0026] According to the present invention, a method for preparing an oxygen-rich microporous carbon-supported platinum catalyst is provided, wherein the molar ratio of platinum precursor to surfactant is 1:1 to 1:0.2.

[0027] Preferably, the molar ratio of the platinum precursor to the surfactant is 1:0.5. According to the present invention, a method for preparing an oxygen-enriched microporous carbon-supported platinum catalyst is provided, wherein the platinum precursor is any one of chloroplatinic acid, platinum chloride, and platinum acetylacetonate.

[0028] According to the present invention, a method for preparing an oxygen-enriched microporous carbon-supported platinum catalyst is provided, wherein the surfactant is any one of polyvinylpyrrolidone, oleic acid oleamine, hexadecyltrimethylammonium bromide, and dodecyltrimethylammonium bromide.

[0029] Preferably, the surfactant is polyvinylpyrrolidone.

[0030] According to the preparation method of the oxygen-enriched microporous carbon-supported platinum catalyst provided by the present invention, in step 3), the reflux heating temperature is 120-160℃ and the heating time is 1-10h.

[0031] Preferably, the reflux heating temperature is 160°C and the heating time is 4 hours.

[0032] The present invention also provides an application of the oxygen-enriched microporous carbon-supported platinum catalyst as described above, which can be used to prepare hydrogen fuel cells.

[0033] Preferably, the oxygen-rich microporous carbon-supported platinum catalyst is used to prepare hydrogen fuel cells that operate under low humidity conditions.

[0034] This invention provides an oxygen-enriched microporous carbon-supported platinum catalyst, its preparation method, and its application. By using oxygen-enriched microporous carbon as a support and loading large-diameter platinum nanoparticles onto it, the microporous structure of the oxygen-enriched microporous carbon support and the hydrophilic oxygen-containing functional groups attached to its surface can effectively store water within the micropores. Combined with the large-diameter platinum nanoparticles, this improves the water retention capacity of the membrane electrode assembly, enhances the utilization rate of the platinum nanoparticles, and improves the catalytic activity of the catalyst. As a result, the catalyst still exhibits excellent output performance in fuel cell testing under low humidity conditions, making it suitable for large-scale industrial production and showing broad application potential in air-cooled fuel cell stacks. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0036] Figure 1 The XRD patterns of the catalysts in Example 1 and Comparative Example 4 are shown below. Figure 2 The graph shows the polarization performance of the catalysts in Examples 1, 2 and 3 tested in a hydrogen-air fuel cell without humidification. Figure 3 The graph shows the polarization performance of the catalysts in Comparative Examples 1, 2, 3, and 4 in hydrogen-air fuel cells under no humidification conditions. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0038] The following is combined Figures 1-3 This invention describes an oxygen-enriched microporous carbon-supported platinum catalyst suitable for low-humidity conditions, its preparation method, and its application.

[0039] Where specific techniques or conditions are not specified in the examples, they shall be performed in accordance with the techniques or conditions described in the literature in this field, or in accordance with the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased through legitimate channels.

[0040] Example 1 A method for preparing an oxygen-enriched microporous carbon-supported platinum catalyst includes the following steps: Step 1) Constructing microporous carbon material: Black Pearls 2000 and KOH are mixed at a mass ratio of 1:4 and placed in a corundum crucible. The mixture is heated to 900°C in a tube furnace for high-temperature activation. The mixture is then kept at this temperature for 120 minutes under an inert atmosphere. After natural cooling, the activated microporous carbon material is obtained. Step 2) Preparation of oxygen-enriched microporous carbon support: The microporous carbon material obtained in step 1) is washed with hydrochloric acid and deionized water until neutral, and then immersed in a 3 mol / L concentrated nitric acid solution. The acid oxidation reaction is carried out under oil bath conditions at a temperature of 100℃ for 4 h. After filtration and drying, the oxygen-enriched microporous carbon support is obtained. Step 3) Preparation of platinum nanoparticles: Dissolve chloroplatinic acid and polyvinylpyrrolidone in ethylene glycol at a molar ratio of 1:0.5 and transfer to a three-necked flask equipped with a reflux device. Adjust the pH of the solution to 10 using 0.1 mol / L NaOH solution as a pH adjuster. After reflux heating at 160 °C for 4 h under argon protection, centrifuge to obtain platinum nanoparticles. Step 4) Catalyst Preparation: The oxygen-enriched microporous carbon support obtained in Step 2) and the platinum nanoparticles obtained in Step 3) are mixed and treated with ultrasonic power of 200W for 60 min. After centrifugation and washing, the catalyst is obtained after vacuum drying at 60℃. The catalyst comprises an oxygen-enriched microporous carbon support and platinum nanoparticles supported on the oxygen-enriched microporous carbon support. The oxygen-enriched microporous carbon support is a porous carbon material containing microporous structures and oxygen-containing functional groups on its surface. The volume fraction of micropores in the oxygen-enriched microporous carbon support is 58%, and its surface oxygen content is 15%. The particle size of the platinum nanoparticles is 4 nm, and the mass content of platinum in the catalyst is 50 wt%.

[0041] Example 2 A method for preparing an oxygen-enriched microporous carbon-supported platinum catalyst is basically the same as that in Example 1, except that: in step 1), the mass ratio of Black Pearls 2000 to KOH is replaced with 1:3; and in step 4), the mass content of platinum is controlled to be 70wt%.

[0042] Example 3 A method for preparing an oxygen-enriched microporous carbon-supported platinum catalyst is basically the same as that in Example 1, except that in step 2), the temperature of the acid oxidation reaction is replaced with 80°C.

[0043] Example 4 A method for preparing an oxygen-enriched microporous carbon-supported platinum catalyst is basically the same as that in Example 1, except that: in step 1), the mass ratio of Black Pearls 2000 to KOH is replaced with 1:5; and in step 4), the mass content of platinum is controlled to be 30wt%.

[0044] Example 5 A method for preparing an oxygen-enriched microporous carbon-supported platinum catalyst is basically the same as that in Example 1, except that in step 2), the temperature of the acid oxidation reaction is replaced with 120°C.

[0045] The particle size, mass content of platinum, and performance of the oxygen-enriched microporous carbon support in the platinum catalysts prepared in Examples 1-5 are shown in Table 1. Table 1. Particle size and mass content of platinum in the oxygen-enriched microporous carbon-supported platinum catalysts prepared in Examples 1-5, and the performance of the oxygen-enriched microporous carbon support.

[0046] The oxygen content on the surface of the oxygen-rich microporous carbon support was detected by X-ray photoelectron spectroscopy (XPS). The mass content of platinum was determined by inductively coupled plasma atomic emission spectrometry (ICP-AES). For specific determination methods, please refer to "Chen T, Qiu C, Zhang X, et al. An ultrasmall ordered high-entropy intermetallic with multiple active sites for the oxygen reduction reaction[J]. Journal of the American Chemical Society, 2023, 146(1): 1174-1184."

[0047] Comparative Example 1 A method for preparing an oxygen-enriched microporous carbon-supported platinum catalyst is basically the same as that in Example 1, except that: step 1) of activating Black Pearls 2000 with KOH at high temperature is not included, and step 2) directly uses Black Pearls 2000 for acid oxidation treatment.

[0048] Comparative Example 2 A method for preparing an oxygen-enriched microporous carbon-supported platinum catalyst is basically the same as that in Example 1, except that step 2) of acid oxidation treatment of the microporous carbon material is not included.

[0049] Comparative Example 3 A method for preparing an oxygen-enriched microporous carbon-supported platinum catalyst is basically the same as that in Example 1, except that steps 1) and 2) are not included, and Black Pearls 2000 is neither activated by KOH at high temperature nor subjected to acid oxidation.

[0050] Comparative Example 4 A method for preparing an oxygen-enriched microporous carbon-supported platinum catalyst is described, with steps largely the same as in Example 1, except that step 3) employs an impregnation reduction method. Specifically, chloroplatinic acid hydrate and deionized water are ultrasonically mixed at a mass ratio of 1:1 to form a chloroplatinic acid solution. Then, Black Pearls 2000, with the same mass as the Pt in the solution, which has undergone KOH activation and HNO3 oxidation treatment, is added. After further ultrasonic mixing, the mixture is pre-frozen at -15°C for 1 hour in a freeze dryer, then cooled to -40°C, and subsequently heated to 70°C at a heating rate of 10°C / min, maintaining a vacuum throughout the process. The sublimated and dried material is then transferred to a tube furnace, where a 10 vol% H2 / N2 atmosphere is introduced, and the furnace is heated to 200°C and held for 2 hours. After natural cooling, the catalyst is obtained.

[0051] Test Example 1 In this test example, the supports obtained during the preparation of oxygen-enriched microporous carbon-supported platinum catalysts in Examples 1-3 and Comparative Examples 1-3 were subjected to N2 adsorption. The specific surface area and the proportion of micropores and mesopores of the supports were determined by the Brunauer-Emmett-Teller (BET) method and pore size analysis based on quenched solid density functional theory (QSDFT). The results are shown in Table 2.

[0052] Table 2 Performance test table of carbon supports prepared in Examples 1-3 and Comparative Examples 1-3

[0053] As can be seen from Table 2, comparing Examples 1-3, the oxygen-enriched microporous carbon support obtained by activation with a mass ratio of Black Pearls 2000 to KOH of 1:4 and an acid oxidation temperature of 100℃ has the highest specific surface area and micropore ratio. Compared with Comparative Examples 1-3, the specific surface area and micropore ratio of the oxygen-enriched microporous carbon support corresponding to Example 1 are significantly higher than those of Comparative Examples 1-3. This indicates that high-temperature activation and acid oxidation of the carbon precursor can effectively increase the specific surface area of ​​the oxygen-enriched microporous carbon support, increase the micropore ratio, effectively improve the hydrophilicity of the support, delay the expulsion of water from the micropores, and improve the water retention capacity of the membrane electrode.

[0054] Test Example 2 This test example uses X-ray diffraction to analyze the oxygen-rich microporous carbon-supported platinum catalysts prepared in Example 1 and Comparative Example 4. The XRD patterns are shown below. Figure 1 As shown, the crystal phase (platinum) of the catalysts prepared by different methods matched the standard card Pt (JCPDS04-0802). According to the Scherrer formula, the crystal sizes of Example 1 and Comparative Example 4 were calculated to be 5.0 nm and 2.8 nm, respectively. This indicates that when the catalyst was prepared in Example 1, chloroplatinic acid was reacted with a surfactant and a pH adjuster under reflux heating. Under the combined action of the surfactant and the pH adjuster, larger platinum nanoparticles were generated, which improved the utilization rate of platinum in the catalyst.

[0055] Test Example 3 This test example evaluated the performance of the catalysts prepared in Examples 1-3 and Comparative Examples 1-4 in a hydrogen-air fuel cell under low humidity conditions. The test method was as follows: both examples and comparative examples were used as cathode catalysts, and the Pt metal loading was controlled at 0.3 mg Pt / cm³. 2The anode uses a commercial 40% Pt / C catalyst (Johnson Matthey HiSPEC4000), with a Pt metal loading of 0.1 mg Pt / cm³. 2 The battery temperature was 50℃, with hydrogen gas introduced at the anode and air introduced at the cathode. The stoichiometric ratio was 1.3:2.5, and the back pressure was 0.05 MPa. No humidification was used at either the anode or cathode. After battery activation and steady-state performance stabilization, polarization curve testing was performed, with the voltage gradually decreasing from 1V to 0.3V. The changes in current density were measured and recorded. The results are as follows: Figure 2 and Figure 3 As shown.

[0056] Depend on Figure 2 It can be seen that the power densities corresponding to a current density of 1 ampere / cm² in Examples 1, 2, and 3 are 0.716, 0.692, and 0.678 watts / cm², respectively, and the corresponding maximum power densities are 1.15, 1.1, and 1.06 watts / cm², respectively.

[0057] Depend on Figure 3 It can be seen that the power densities corresponding to a current density of 1 ampere / cm² for Comparative Example 1 without activation treatment and Comparative Example 2 without acid oxidation treatment are only 0.62 and 0.63 watts / cm², respectively, and the corresponding maximum power densities are only 0.94 and 0.91 watts / cm², respectively, which are significantly lower than those of Example 1.

[0058] The power densities of the conventional carbon-supported Pt catalyst (Comparative Example 3) and the catalyst prepared by the impregnation reduction method (Comparative Example 4, with a platinum particle size of 2.8 nm) at a current density of 1 A / cm² are only 0.605 and 0.66 W / cm², respectively, and the corresponding maximum power densities are only 0.744 and 0.88 W / cm², respectively, which are also significantly lower than those in Example 1.

[0059] Test Example 4: Experimental Study on the Effect of Micropore Volume Ratio on the Performance of Oxygen-Enriched Microporous Carbon-Supported Platinum Catalyst in Hydrogen-Air Fuel Cells under Low Humidity Conditions This test case investigates the effect of different micropore volume ratios in an oxygen-enriched microporous carbon support on the performance of the catalyst in a hydrogen-air fuel cell under low humidity conditions. The test method for the fuel cell performance is the same as in Test Case 3, and the results are shown in Table 3. Table 3. Effect of micropore ratio on catalyst performance in hydrogen-air fuel cells under low humidity conditions.

[0060] As shown in the table above, the cell formation rate first increases and then decreases as the micropore volume ratio increases, indicating that the micropore volume ratio affects the performance of the fuel cell. When the micropore volume ratio is 50-70%, the cell performance can achieve better results.

[0061] Based on the above tests and analyses, the method of the present invention (Examples 1-5) can prepare catalysts with large-diameter platinum nanoparticles supported on oxygen-enriched microporous carbon supports. When the micropore volume ratio in the oxygen-enriched microporous carbon support is 50-70% and the particle size of the supported platinum nanoparticles is 3-5 nm, the oxygen-enriched microporous carbon supported platinum catalyst can effectively alleviate the performance degradation caused by the weak water retention capacity of the membrane electrode under low humidity conditions, and can effectively improve the output performance of hydrogen-air fuel cells under low humidity conditions.

[0062] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An oxygen-rich microporous carbon supported platinum catalyst, characterized in that, The oxygen-rich microporous carbon supported platinum catalyst comprises an oxygen-rich microporous carbon carrier and platinum nanoparticles supported on the oxygen-rich microporous carbon carrier, the oxygen-rich microporous carbon carrier contains a microporous structure, and the surface of the oxygen-rich microporous carbon carrier is connected with hydrophilic oxygen-containing functional groups, and the particle size of the platinum nanoparticles is 3-5 nm; the volume fraction of micropores in the oxygen-rich microporous carbon carrier is 50-70%.

2. The oxygen-rich microporous carbon supported platinum catalyst according to claim 1, characterized in that, The oxygen content of the surface of the oxygen-rich microporous carbon carrier is 10-20%.

3. The oxygen-rich microporous carbon supported platinum catalyst according to claim 1 or 2, characterized in that, The mass content of platinum in the oxygen-rich microporous carbon supported platinum catalyst is 30wt%-70wt%.

4. A process for the preparation of an oxygen enriched microporous carbon supported platinum catalyst according to any one of claims 1 to 3, characterized in that, The method comprises the following steps: Step 1) constructing a microporous carbon material: mixing a carbon precursor and an activating agent at a mass ratio of 1:3-1:5, then performing activation treatment, and then performing heat preservation treatment in an inert atmosphere, and then cooling to obtain a microporous carbon material; Step 2) preparing an oxygen-rich microporous carbon carrier: washing the microporous carbon material obtained in step 1) to neutral, then immersing in a concentrated nitric acid solution to perform acid oxidation treatment, then filtering and drying to obtain an oxygen-rich microporous carbon carrier; Step 3) preparing platinum nanoparticles: weighing a platinum precursor and a surfactant, dissolving them in a solvent, adding a pH adjuster to adjust the pH to 8-12, then performing reflux heating under an argon atmosphere, and then centrifuging to obtain platinum nanoparticles; Step 4) catalyst preparation: mixing the oxygen-rich microporous carbon carrier obtained in step 2) and the platinum nanoparticles obtained in step 3) under ultrasonic conditions, then performing centrifugal washing, and then vacuum drying.

5. The method for preparing an oxygen-enriched microporous carbon-supported platinum catalyst according to claim 4, characterized in that, In step 1), the temperature rising program of the activation treatment is heating to 800-1000℃ at a temperature rising rate of 5-8℃ / min, and the heat preservation time is 1-120 min; and / or, the activating agent is at least one of potassium hydroxide and sodium hydroxide.

6. The method for preparing an oxygen-enriched microporous carbon-supported platinum catalyst according to claim 4, characterized in that, The temperature of the acid oxidation treatment is 80-120℃, and the acid oxidation treatment time is 2-6 h.

7. A method of preparing an oxygen-rich microporous carbon supported platinum catalyst according to any one of claims 4-6, characterized in that, The molar ratio of the platinum precursor to the surfactant is 1:1-1:0.

2.

8. The method for preparing an oxygen-enriched microporous carbon-supported platinum catalyst according to claim 7, characterized in that, The surfactant is any one of polyvinylpyrrolidone, oleic acid oleylamine, cetyltrimethylammonium bromide, and dodecyltrimethylammonium bromide.

9. A method of preparing an oxygen-rich microporous carbon supported platinum catalyst according to any one of claims 4-6, characterized in that, In step 3), the temperature of the reflux heating is 120-160℃, and the reflux heating time is 1-10 h.

10. Use of the oxygen-enriched microporous carbon supported platinum catalyst according to any one of claims 1 to 3, characterized in that, Application of the oxygen-rich microporous carbon supported platinum catalyst in a hydrogen fuel cell.

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