Catalyst for enhancing electro-catalytic oxygen reduction activity by platinum cluster, catalyst slurry, working electrode and preparation method

Abstract

The invention discloses a platinum cluster enhanced electro-catalytic oxygen reduction activity catalyst, catalyst slurry, a working electrode and a preparation method, the catalyst comprises a graphite flake loaded with a low loading amount of Pt nanocluster, namely Pt-D / O-C; wherein the low loading capacity is less than 1.5 wt%. According to the present invention, the cheap, easily available and efficient carbon material is adopted as the electrode, such that the operation is simple, the carbon electrode has good stability and can be recycled for multiple times, the ORR activity can be enhanced and the cost can be reduced in the aspect of the effect, the problems of carbon corrosion, Pt aggregation and the like during the reaction process can be avoided, and the great application potential in the industry can be provided. Meanwhile, the catalyst slurry, the working electrode and the preparation method provided by the invention also have the same effect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrocatalytic oxygen reduction, and particularly relates to a platinum cluster enhanced catalyst for electrocatalytic oxygen reduction activity, a catalyst slurry, a working electrode and a preparation method. BACKGROUND

[0002] Fuel cells convert part of the Gibbs free energy in the chemical energy of fuel into electrical energy through electrochemical reactions, and are not limited by the Carnot cycle effect, thus having a high energy conversion efficiency. Compared with traditional combustion technology, fuel cells have the advantages of high fuel energy conversion efficiency, low noise and zero emission, and can be widely applied to vehicles such as cars, planes and trains, and fixed power stations, and are considered to be the most promising clean and efficient energy technology in the 21st century. However, compared with the anode hydrogen oxidation reaction (HOR), the cathode oxygen reduction reaction (ORR) is relatively slow in kinetics due to the inclusion of multiple basic reactions and the diversification of reaction paths, and generally requires the action of a noble metal platinum (Pt) catalyst to meet the requirements of practical application, and is relatively high in price and cost.

[0003] The commonly used commercial catalyst in fuel cells is mainly a platinum-carbon (Pt / C) catalyst, which is composed of nanoscale platinum particles and a large specific surface area activated carbon supporting the platinum particles. However, in actual industrial applications, the Pt / C catalyst will have a series of problems such as carbon corrosion and Pt aggregation, thereby affecting the electrochemical active area and leading to a decline in catalytic performance and a relatively short service life. Therefore, in view of the shortcomings of the Pt / C catalyst, some existing technologies give some new directions for catalysts:

[0004] The prior art 1 (Molten-Salt Electrochemical-Assisted Synthesis of the CeO2-Oy@GC Composite-Supported Pt Clusters with a Pt-O-Ce Structure for the Oxygen Reduction Reaction) prepared a high-loading and high-dispersity Pt cluster catalyst (PtAC / CeO2-OV@GC), and structure characterization and theoretical calculation showed that the bonding of Pt with high electronegativity O helped to form a strong interaction between Pt and CeO2; at the same time, the charge redistribution of the Pt-O-Ce structure reduced the d-band center of Pt and weakened the adsorption energy of oxygen-containing species, thereby effectively improving the ORR electrocatalytic activity of the PtAC / CeO2-OV@GC. In addition, the introduction of a graphitized carbon carrier and a firm Pt-Ox bond further enhanced the corrosion resistance of the catalyst. However, the material of the prior art 1 has a mass activity that is only 2.7 times that of the commercial Pt / C under acidic conditions, and the performance decreases by 25.1% after 7h of reaction, and the catalyst activity is not good.

[0005] Prior art 2 (P-O functional group anchoring Pt-Co electrocatalyst for high-durability PEMFCs) increases the interaction between PtCo alloy particles and carbon carriers by introducing P-O functional groups in the carbon carrier, thereby alleviating particle agglomeration and growth during the electrochemical process, and improving the durability of the catalyst. The PEMFC assembled with the PtCo / P2.73Ox-KB catalyst also exhibits excellent performance and durability, reaching the DOE target in 2025, proving the practicability of the material. However, the prior art 2 found that the Co atom loss was relatively serious during the stability test, and the P element content also decreased slightly, and the stability was weak.

[0006] Prior art 3 (Spin occupancy regulation of the Ptd-orbital for a robust low-Pt catalyst towards oxygen reduction) constructs a stable low-Pt-based electrocatalyst composed of atomically dispersed FeSAs-N-C and ultrafine PtFe nanocrystals. The spin occupancy regulation behavior of the Ptd orbital in ORR is studied from the electronic level, and a strategy combining real-time magnetic response recording electrochemical reactions, in-situ spectroscopy and theoretical calculation analysis is further developed to determine the 4e- dissociation pathway. The mass activity of the catalyst at 0.9 volts is about 4.6 times higher than that of Pt / C, which is 1.7 times the 2025 DOE activity target, and there is no significant performance loss in the proton exchange membrane fuel cell after running for 220 hours, which is much higher than the commercial Pt / C (120 hours current density loss 60%). However, the Pt content of the prior art 3 is 6.97wt%, and the high Pt content will increase the cost.

[0007] Therefore, it is important to develop an ORR catalyst with high activity, high stability and low loading for efficient energy conversion. SUMMARY

[0008] The purpose of the present application is to overcome the shortcomings of the prior art and provide a platinum cluster enhanced electrocatalytic oxygen reduction activity catalyst, catalyst slurry, working electrode and preparation method.

[0009] The purpose of the present application is achieved by the following technical solutions:

[0010] In a first aspect of the present application, a platinum cluster enhanced electrocatalytic oxygen reduction activity catalyst is provided, comprising a graphite sheet loaded with a low loading of Pt nanoclusters, i.e. Pt-D / O-C;

[0011] The low load is less than 1.5 wt%.

[0012] Furthermore, the low load is 1.2 wt%.

[0013] A second aspect of the present invention provides a method for preparing a catalyst as described in the first aspect, comprising the following steps:

[0014] Commercial graphite sheets are cut into preset shapes and cleaned to obtain clean graphite sheets;

[0015] In the electrochemical workstation, a three-electrode system is used, with the clean graphite sheet as the working electrode, the carbon rod as the counter electrode, and Hg / HgO as the reference electrode. The electrolyte is KOH. Oxidation is carried out under constant current conditions to obtain oxidized graphite sheet OC. Then, reduction is carried out under constant current conditions to obtain graphite sheet D / OC rich in hydroxyl functional groups and carbon defects.

[0016] In the electrochemical workstation, a three-electrode system is used, with the graphite sheet D / OC rich in hydroxyl functional groups and carbon defects as the working electrode, the Pt sheet as the counter electrode, and Hg / HgO as the reference electrode. The electrolyte is KOH. Under constant current conditions, Pt clusters are electrodeposited to obtain uniformly distributed Pt nanoclusters, which is the catalyst Pt-D / OC.

[0017] Furthermore, the oxidation under constant current conditions specifically refers to: using 10 mA cm⁻¹ -2 Oxidize for 30 minutes under constant current conditions;

[0018] The reduction under constant current conditions specifically refers to: at -10mAcm -2 Reduced for 30 minutes under constant current conditions;

[0019] The electrodeposition of Pt clusters under constant current conditions specifically involves: at -200 mA / cm². -2 Pt clusters were electrodeposited under constant current conditions for 10 minutes, resulting in uniformly distributed Pt clusters with an average particle size of 1.5 nm.

[0020] A third aspect of the present invention provides a catalyst slurry for enhancing electrocatalytic oxygen reduction activity with platinum clusters, comprising 2-5 parts by weight of Pt-D / OC catalyst powder as described in the first aspect, 20-50 parts by weight of a perfluorosulfonic acid polymer solution, and 900-1100 parts by weight of an isopropanol solution.

[0021] Furthermore, the perfluorosulfonic acid polymer solution is a 5wt% Nafion solution, and the isopropanol solution is a mixture of isopropanol and deionized water.

[0022] In a fourth aspect, the present application provides a preparation method of the catalyst slurry according to the third aspect, comprising the following steps:

[0023] Mixing the perfluorosulfonic acid type polymer solution, isopropyl alcohol and water to obtain a mixture;

[0024] Adding the Pt-D / O-C catalyst powder into the mixture, fully shaking and ultrasonic processing to configure a uniform slurry.

[0025] In a fifth aspect, the present application provides a working electrode with platinum cluster enhanced electrocatalytic oxygen reduction activity, comprising a working electrode body and a catalyst layer on the surface of the working electrode body, wherein the catalyst layer adopts the catalyst slurry according to the fourth aspect.

[0026] The working electrode body is a glassy carbon rotating ring-disk electrode or a hydrophobic carbon paper.

[0027] In a sixth aspect, the present application provides a preparation method of the working electrode with platinum cluster enhanced electrocatalytic oxygen reduction activity according to the fifth aspect, wherein when the working electrode body is a glassy carbon rotating ring-disk electrode, the preparation method comprises the following steps:

[0028] Polishing the surface of the rotating ring-disk electrode clean;

[0029] Uniformly dropping the catalyst slurry on the glassy carbon rotating ring-disk electrode in two times;

[0030] After drying into a film, adding electrolyte on the surface and standing for a period of time, so as to fully soak.

[0031] In a seventh aspect, the present application provides a preparation method of the working electrode with platinum cluster enhanced electrocatalytic oxygen reduction activity according to the fifth aspect, wherein when the working electrode body is a hydrophobic carbon paper, the preparation method comprises the following steps:

[0032] Placing the hydrophobic carbon paper on a hot plate wrapped with tin paper;

[0033] Uniformly dropping the catalyst slurry on the center of the hydrophobic carbon paper at a heating temperature.

[0034] The present application has the following beneficial effects:

[0035] The present application provides an ORR catalyst with high activity, high stability and low loading capacity, which uses cheap and efficient carbon material as electrode, and has the advantages of simple operation, good stability of carbon electrode and multiple recycling, and can not only enhance the ORR activity and reduce the cost, but also can not cause carbon corrosion and Pt aggregation in the reaction process, which has great application potential in industry. Meanwhile, the catalyst slurry, working electrode and preparation method provided by the present application also have the same effects. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 is a linear voltammetry scan (LSV) test comparison chart of Pt-D / O-C and Pt / C rotating ring-disk electrodes in embodiment 2 of the present application;

[0037] Figure 2 is a comparison chart of the number of transferred electrons of Pt-D / O-C and Pt / C rotating ring-disk test in embodiment 2 of the present application;

[0038] Figure 3 is a schematic diagram of a three-electrode flow cell test device in embodiment 3 of the present application;

[0039] Figure 4 is a linear voltammetry scan (LSV) test comparison chart of Pt-D / O-C and Pt / C three-electrode flow cell test in embodiment 3 of the present application;

[0040] Figure 5 is a comparison chart of the constant potential polarization curve of Pt-D / O-C and Pt / C three-electrode flow cell test at -0.55 V vs. RHE in embodiment 3 of the present application;

[0041] Figure 6 is a transmission electron microscope image and particle size distribution chart taken before the Pt / C three-electrode flow cell test in embodiment 3 of the present application;

[0042] Figure 7 is a transmission electron microscope image and particle size distribution chart taken after the Pt / C three-electrode flow cell test in embodiment 3 of the present application;

[0043] Figure 8 is a comparison chart of particle size before and after the Pt / C three-electrode flow cell test in embodiment 3 of the present application;

[0044] Figure 9 is a comparison chart of Pt 4f X-ray photoelectron spectroscopy before and after the Pt / C three-electrode flow cell test in embodiment 3 of the present application;

[0045] Figure 10 is a transmission electron microscope image and particle size distribution chart taken before the Pt-D / O-C three-electrode flow cell test in embodiment 3 of the present application;

[0046] Figure 11 is a transmission electron microscope image and particle size distribution chart taken after the Pt-D / O-C three-electrode flow cell test in embodiment 3 of the present application;

[0047] Figure 12 is a comparison chart of X-ray absorption spectroscopy results before and after the Pt-D / O-C three-electrode flow cell test in embodiment 3 of the present application;

[0048] Figure 13Figure is a comparison chart of Pt 4f results of X-ray photoelectron spectroscopy before and after Pt-D / O-C three-electrode flow cell test in Example 3 of the present application. DETAILED DESCRIPTION

[0049] The technical solutions of the present application are described below in detail with reference to the drawings. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.

[0050] In the description of the present application, it should be noted that the directions or positional relationships indicated by "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like are described based on the directions or positional relationships described in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0051] In the description of the present application, it should be noted that, unless otherwise explicitly specified and limited, "mounting", "connection" and "connection" should be understood in a broad sense, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through an intermediate medium; it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0052] In addition, the technical features involved in the different embodiments of the present application described below can be combined with each other as long as there is no conflict.

[0053] Preparation of catalyst in Example 1

[0054] 1. Pretreatment method of graphite sheet:

[0055] Cut the commercial graphite sheet into 1x2cm sheet shape, and put the cut graphite sheet in a beaker, and then ultrasonic in acetone, anhydrous ethanol, dilute hydrochloric acid and deionized water for 40min. Before changing the solution for ultrasonic, the remaining reagents on the surface of the graphite sheet are cleaned with deionized water to prevent reaction. The cleaned graphite sheet is stored in a container containing anhydrous ethanol for standby.

[0056] 2. Preparation of catalyst

[0057] First, in CHI 760E electrochemical workstation, using a three-electrode system, the clean graphite sheet (C, 1x1cm) was used as the working electrode, carbon rod as the counter electrode, Hg / HgO as the reference electrode, and 1.0M KOH as the electrolyte; in 1.0M KOH, the clean graphite sheet was oxidized at 10mAcm -2 for 30 minutes, and then reduced at -10mAcm -2 for 30 minutes to obtain the graphite sheet (D / O-C) rich in hydroxyl functional groups and carbon defects.

[0058] Then, in 1.0M KOH, using the prepared D / O-C, clean Pt sheet (1x1cm) and Hg / HgO as the working electrode, counter electrode and reference electrode, respectively, Pt cluster electrodeposition was carried out at a constant current of -200mAcm -2 for 10 minutes, and the average particle size of the Pt clusters (Pt-D / O-C) obtained was 1.5nm.

[0059] Example 2 Catalyst slurry preparation, glassy carbon rotating ring-disk electrode preparation and ORR performance test

[0060] 1. Catalyst slurry preparation and working electrode preparation

[0061] 2mg of Pt-D / O-C prepared in Example 1 (containing 0.024g of Pt) was dispersed in 20uL of Nafion (5wt%), 980uL of isopropanol solution (a mixture of 780uL of isopropanol and 200uL of deionized water), and was shaken and ultrasonically treated for at least 1h to prepare a uniform catalyst slurry.

[0062] Then the surface of the rotating ring-disk electrode was polished clean, and 10uL of the slurry was evenly dropped on the glassy carbon (diameter 5mm) rotating ring-disk electrode in two times, and after drying into a film, the electrolyte was added to the surface and left for a period of time to allow it to fully soak, and then assembled for testing.

[0063] As a comparison, 2mg of Pt-D / O-C catalyst was replaced by 2mg of Pt / C catalyst (containing 0.4mg of Pt).

[0064] 2. ORR performance test

[0065] Pt-D / O-C oxygen reduction performance was measured in a CHI 760E electrochemical workstation with a three-electrode system in 0.1 M KOH (pH = 12.6). A carbon rod was used as the counter electrode, a Hg / HgO electrode (with 1 M KOH solution as internal filling) as the reference electrode, and a rotating ring-disk electrode as the working electrode. The electrolyte was 0.1 M KOH solution. All potentials were converted to the electrode potential of the reversible hydrogen electrode (RHE) by the following equation: E(RHE) = E(Hg / HgO) + 0.098 + 0.0592 pH.

[0066] Before testing, high purity nitrogen (99.999%) was bubbled into the electrolyte for at least 30 minutes, with a gas flow rate of 50 mL min -1 to eliminate dissolved oxygen in the electrolyte. Then, cyclic voltammetry (CV) tests were performed at a scan rate of 100 mV / s in the potential range of 0.1-1 V vs. RHE until the curves overlapped, in order to eliminate impurities that might be adsorbed on the electrode surface. After that, background current tests were performed using linear sweep voltammetry (LSV) method at a scan rate of 10 mV / s in the potential range of 0.1-1 V vs. RHE. Then the gas bubbled into the electrolyte was changed to oxygen for at least 30 min, with a gas flow rate of 50 mL min -1 , after ensuring that the solution was saturated with oxygen, the rotation speed of the rotating ring-disk electrode was adjusted to 1600 rpm, and multiple LSV tests were performed at a scan rate of 10 mV / s in the potential range of 0.1-1 V vs. RHE to obtain the ORR polarization curve, in which a potential of 1.3 V vs. RHE was applied to the platinum ring to oxidize the generated H2O2 and the ring current was recorded.

[0067] The number of transferred electrons (n) can be calculated using the LSV curve with disk current and ring current obtained from the rotating ring-disk electrode test by the following equation:

[0068]

[0069] where i ring and i disk represent the ring current and disk current, respectively (both background currents are deducted), and N is the collection coefficient (N = 0.37).

[0070] 3. Test results show that:

[0071] The ORR performance test results are shown in Figure 1 At 0.6 V vs. RHE, the Pt-D / O-C catalyst showed a mass activity as high as 205 mA mg pt -1 -1 pt -1) is 16 times higher than that of Pt / C. The electron transfer number of Pt-D / O-C oxygen reduction is calculated to be 3.9 (as shown in Figure 2 ) in the range of 0.8-1.0 V vs. RHE, which is almost the same as that of Pt / C, indicating that the main product of Pt-D / O-C oxygen reduction reaction is water.

[0072] Example 3 Catalyst slurry preparation, hydrophobic carbon paper preparation and ORR performance test

[0073] This example corresponds to large current amplification at room temperature.

[0074] 1. Catalyst slurry preparation and working electrode preparation

[0075] Take 4 mg of Pt-D / O-C catalyst powder prepared in Example 1 (containing 0.048 g of Pt), add 50 uL of Nafion (5 wt%) solution, 1950 uL of isopropanol solution (a mixture of 975 uL of isopropanol and 975 uL of deionized water), shake thoroughly and ultrasonic for at least 60 min to prepare a uniform slurry.

[0076] Place the hydrophobic carbon paper on the heating plate wrapped with tin foil, and evenly drop the catalyst slurry on the center of the hydrophobic carbon paper (2.5 x 2.5 cm) at a temperature of 60°C, and the coverage area of the catalyst is 4 cm -2 , i.e. 2 x 2 cm.

[0077] As a comparison, replace the Pt-D / O-C catalyst powder with commercial Pt / C catalyst (containing 0.8 mg of Pt).

[0078] 2. ORR performance test

[0079] The working electrode (cathode) is the hydrophobic carbon paper with Pt-D / O-C catalyst powder dropped on it, and the anode is the commercial Ru / Ir alloy loaded on titanium felt. The size of the electrolytic cell is 2 x 2 cm, and the electrolyte is 1M KOH solution. The gas flow rate is 50 mL min -1 , and the liquid flow rate of the cathode and anode is 50 mL min -1 . The reference electrode is a mercury oxide electrode. Assemble according to the three-electrode assembly method, and the schematic diagram is as follows Figure 3 . After assembly, perform LSV test at a scan rate of 100 mV / s in the range of 0.1-1 V vs. RHE until the polarization curves coincide, and then perform constant potential polarization (E-t) test at -0.55 V vs. RHE to evaluate the stability of Pt-D / O-C catalyst in oxygen reduction reaction. As a comparison, replace the Pt-D / O-C catalyst powder with commercial Pt / C catalyst.

[0080] 3. Test results

[0081] As Figure 4 , the mass activity of Pt-D / O-C was as high as 55.1 A mg Pt -1 at 0.2 V vs. RHE, while that of Pt / C was 3.4 A mg Pt -1 . Subsequently, long-term stability tests were performed at a reduction potential of -0.55 V vs. RHE. The initial current density of both Pt electrodes was about -600 mA cm -2 , but Pt / C (0.2 mg Pt -1 cm -2 ) decayed to 41% within 30 h, while Pt-D / O-C (0.012 mg Pt -1 cm -2 ) maintained 92.3% of its activity after 310 h of testing (as Figure 5 ). Transmission electron microscopy (TEM) results before and after the stability test showed that the size of Pt / C aggregated from 5 nm to 15 nm (as Figure 8 ), where Figure 6 , Figure 7 are TEM tests of commercial Pt / C before and after the flow cell test, respectively. X-ray photoelectron spectroscopy (XPS) results indicated that its valence state decreased from nearly +2 to 0 (as Figure 9 ). In contrast, the particle size of Pt-D / O-C remained at 1.5 nm Figure 10 and Figure 11 ), and X-ray absorption fine structure (XAFS) indicated that its valence state remained at +3 (as Figure 12 ), which was consistent with the XPS results (as Figure 13 ).

[0082] The above results show that the deactivation of Pt / C is actually caused by the growth of Pt particles during the reaction, and the irreversible deactivation of Pt / C caused by the loss of specific surface area and the reduction of active site number due to particle maturation causes a large economic loss. The unique structure of Pt-D / O-C catalyst can limit the aggregation of Pt clusters, thereby reducing the economic loss caused by catalyst deactivation.

[0083] It should be noted that the main purpose of the ORR rotating ring-disk electrode test in Example 2 is to study the mechanism of electrode reaction, intermediate product and electrochemical performance of the material, and the tested current is a small current; while the flow cell test in Example 3 focuses on evaluating the performance of the material under actual working conditions, such as mass activity, Faraday efficiency, etc., which is usually carried out in an actual three-electrode flow cell setup, can simulate real operating conditions, and provide more accurate performance evaluation. First, the Pt cluster ORR performance is tested by rotating ring-disk test to obtain the number of transferred electrons, and it is confirmed that the main process is 4e- transfer process, that is, the product is mainly water, not hydrogen peroxide. Then, the large current test is carried out by flow cell to evaluate the stability of the catalyst, indicating its potential for industrial application.

[0084] The catalyst for enhancing the electrocatalytic oxygen reduction activity of the platinum cluster, namely Pt-D / O-C, has the advantage that the catalyst exhibits a mass activity of up to 205 mA mg Pt -1 Pt / C catalyst (3 mA mg Pt -1 ) of 16 times at 0.6 V vs. RHE (Example 2). And large current amplification, it is found that its performance can still maintain 92.3% after 310h reaction (Example 3). Compared with the prior art, the mass activity of the material in Prior Art 1 is only 2.7 times that of the commercial Pt / C catalyst under acidic conditions, and the performance decreases by 25.1% after 7h reaction, which is much less efficient than the catalyst in the present application; ICP test in Prior Art 1 found that Co atoms were relatively seriously lost during the stability test, and the content of P element also decreased slightly, while the Pt cluster prepared in the present application still maintains a particle size of about 1.5 nm after 310h stability test; the Pt content in Prior Art 3 is 6.97wt%, while the Pt content in the present application is 1.2wt%.

[0085] In summary, the present application provides an ORR catalyst with high activity, high stability and low loading, which uses a low-cost graphite sheet as a carrier. The prepared catalyst has a mass activity of up to 16 times that of a commercial Pt / C catalyst with a Pt content of only 1.2wt%, and the performance can still maintain 92.3% after 310h flow cell amplification reaction, with long stability. Therefore, using a cheap and efficient carbon material as an electrode, the operation is simple, the carbon electrode has good stability and can be recycled multiple times, and the effect not only enhances the ORR activity and reduces the cost, but also does not have problems such as carbon corrosion and Pt aggregation during the reaction, which has great application potential in industry. At the same time, the catalyst slurry, working electrode and preparation method provided by the present application also have the same effect.

[0086] Obviously, the above embodiments are merely example for clearly illustrating but not limitation to the embodiments, and on the basis of the above description, other different forms of changes or variations can be made by those skilled in the art. Here, all the embodiments need not and can not be enumerated. The obvious changes or variations derived therefrom are still within the protection scope of the present application.

Claims

1. A catalyst with platinum clusters enhancing electrocatalytic oxygen reduction activity, characterized in that: This includes graphite sheets loaded with low-load Pt nanoclusters, namely Pt-D / OC; The low load is less than 1.5 wt%.

2. The catalyst for enhancing electrocatalytic oxygen reduction activity with platinum clusters according to claim 1, characterized in that: The low load is 1.2 wt%.

3. The method for preparing the catalyst according to claim 1 or 2, characterized in that: Includes the following steps: Commercial graphite sheets are cut into preset shapes and cleaned to obtain clean graphite sheets; In the electrochemical workstation, a three-electrode system is used, with the clean graphite sheet as the working electrode, the carbon rod as the counter electrode, and Hg / HgO as the reference electrode. The electrolyte is KOH. Oxidation is carried out under constant current conditions to obtain oxidized graphite sheet OC. Then, reduction is carried out under constant current conditions to obtain graphite sheet D / OC rich in hydroxyl functional groups and carbon defects. In the electrochemical workstation, a three-electrode system is used, with the graphite sheet D / OC rich in hydroxyl functional groups and carbon defects as the working electrode, the Pt sheet as the counter electrode, and Hg / HgO as the reference electrode. The electrolyte is KOH. Under constant current conditions, Pt clusters are electrodeposited to obtain uniformly distributed Pt nanoclusters, which is the catalyst Pt-D / OC.

4. The method for preparing the catalyst according to claim 3, characterized in that: The oxidation under constant current conditions specifically refers to: using 10 mA cm⁻¹ -2 Oxidize for 30 minutes under constant current conditions; The reduction under constant current conditions specifically refers to: at -10mAcm -2 Reduced for 30 minutes under constant current conditions; The electrodeposition of Pt clusters under constant current conditions specifically involves: at -200 mA / cm². -2 Pt clusters were electrodeposited under constant current conditions for 10 minutes, resulting in uniformly distributed Pt clusters with an average particle size of 1.5 nm.

5. A catalyst slurry for enhancing electrocatalytic oxygen reduction activity using platinum clusters, characterized in that: It includes 2-5 parts by weight of Pt-D / OC catalyst powder as claimed in claim 1 or 2, 20-50 parts by weight of perfluorosulfonic acid polymer solution, and 900-1100 parts by weight of isopropanol solution.

6. The catalyst slurry according to claim 5, characterized in that: The perfluorosulfonic acid polymer solution is a 5wt% Nafion solution; the isopropanol solution is a mixture of isopropanol and deionized water.

7. The method for preparing the catalyst slurry as described in claim 5 or 6, characterized in that: Includes the following steps: A mixture is obtained by mixing a perfluorosulfonic acid polymer solution and an isopropanol solution. Pt-D / OC catalyst powder was added to the mixture, and the mixture was thoroughly shaken and ultrasonically treated to prepare a homogeneous slurry.

8. A working electrode with platinum cluster-enhanced electrocatalytic oxygen reduction activity, characterized in that: It includes a working electrode body and a catalyst layer located on the surface of the working electrode body, wherein the catalyst layer adopts the catalyst slurry of claim 5 or 6; The working electrode body is a glassy carbon rotating ring disk electrode or hydrophobic carbon paper.

9. A method for preparing a working electrode with platinum cluster-enhanced electrocatalytic oxygen reduction activity as described in claim 8, characterized in that: When the working electrode body is a glassy carbon rotating ring disk electrode, the preparation method includes the following steps: Clean the surface of the rotating ring disk electrode; The catalyst slurry was evenly drop-coated onto the glassy carbon rotating ring disk electrode in two stages. After the film dries, add electrolyte to the surface and let it stand for a period of time to fully wet it.

10. A method for preparing a working electrode with platinum cluster-enhanced electrocatalytic oxygen reduction activity as described in claim 8, characterized in that: When the working electrode body is hydrophobic carbon paper, the preparation method includes the following steps: Place the hydrophobic carbon paper on a heating plate wrapped with tin foil; The catalyst slurry is uniformly drop-coated onto the center of the hydrophobic carbon paper at the heating temperature.

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