CN116995254A - Composite structure catalyst for synthesizing supported Pt-MXene and preparation method and application thereof - Google Patents

Abstract

The invention relates to the synthesis of a supported Pt-MXene composite structure catalyst and its preparation method and application, and belongs to the technical field of electrochemical catalyst preparation. The synthetic supported Pt-MXene composite structure catalyst in the present invention uses MXene as the carrier and platinum as the active material. The platinum is evenly dispersed on the surface of the MXene. The platinum includes Pt ⁰ and 0-valent platinum metal particles. Pt ²⁺ . The invention solves the technical problems in the prior art such as complex preparation method of platinum catalyst, large size of platinum metal particles, and poor stability. Utilizing the strong interface interaction between the MXene carrier and the metal, uniformly dispersed platinum nanoparticles are obtained. The size of the platinum particles loaded on the surface of MXene can reach less than 2nm, and the platinum catalytic activity is improved by the electronic coupling effect of the bimetal; there is a strong interaction between the platinum metal particles and MXene. Strong metal-support interface interaction is beneficial to improving the stability and dispersion of the catalyst.

Description

A synthetic supported Pt-MXene composite structure catalyst and its preparation method and application

Technical field

The invention belongs to the technical field of electrochemical catalyst preparation, and in particular relates to a synthetic supported Pt-MXene composite structure catalyst and its preparation method and application.

Background technique

The development of efficient and stable supported platinum catalysts is a key material technology to promote the commercial application of proton exchange membrane fuel cells. Commonly used platinum-carbon catalysts are limited by the poor thermal stability of the carbon support material and insufficient platinum atom specific activity. Looking for non-metallic alkenes with good conductivity and corrosion resistance, MXene, as a new two-dimensional material, has the characteristics of metals and ceramics, has many surface active sites, and is conducive to the formation of highly dispersible platinum dispersed structures, as a replacement for carbon carriers The material has broad application prospects. Evenly distributing platinum on the carrier is the ultimate limit for improving the activity per unit mass of the catalyst, and at the same time bringing catalysis science to a smaller research scale.

Usually achieving nanoscale platinum catalytic structures requires atomic layer deposition (ALD) or chemical vapor deposition (CVD). Although the ALD method can effectively control the deposition morphology of metal on the substrate surface to achieve a nanometer thin film structure (4-5 nanometers) of precious metals, its high cost and low yield limit its industrial application. The CVD method requires high deposition temperatures (generally between 900 and 2000°C). High temperatures can easily cause damage to materials, limiting the selection of substrates and deposition layers, as well as the gas sources involved in the deposition reaction and the residual gas after the reaction. They all have a certain degree of toxicity and pose safety risks.

The information disclosed in this Background section is merely intended to enhance an understanding of the general background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art that is already known to a person of ordinary skill in the art.

Contents of the invention

In order to solve the technical problems in the existing technology that the platinum catalyst preparation method is complicated, the reaction temperature is high, the energy consumption is high, there are safety hazards, and the platinum metal particles are large in size and have poor dispersion and stability, a synthetic supported Pt-MXene composite is provided Structural catalysts and their preparation methods and applications.

The first aspect of this application provides a synthetic supported Pt-MXene composite structure catalyst. The catalyst uses MXene as a carrier and platinum as an active material. The platinum is evenly dispersed on the surface of the MXene. The platinum includes zero-valent platinum. Metal particles (Pt ⁰ ) and Pt ²⁺ .

The platinum atoms (0-valent metal particles of platinum) formed on the surface of MXene have strong interfacial interaction with Pt ²⁺ , which is beneficial to improving the stability and dispersion of the catalyst.

In some embodiments, the particle size of the zero-valent platinum metal particles is 1 to 5 nm;

And/or, the 0-valent platinum metal particles on the surface of the MXene account for more than 70% of the total Pt content.

In some embodiments, the particle size of the zero-valent platinum metal particles can reach 2 nm or less.

A second aspect of the present invention provides a method for preparing the above-mentioned synthetic supported Pt-MXene composite structure catalyst. The preparation method adopts an ethylene glycol reduction impregnation method, including:

Step S1: Add MXene to the urea aqueous solution, mix evenly with ultrasonic, add chloroplatinic acid, stir and mix, then heat the reaction, cool to room temperature after the reaction, and obtain a mixed solution;

Step S2: Add ethylene glycol to the mixed solution obtained in step S1, mix and stir, then heat, continue stirring after heating, and obtain a synthetic supported Pt-MXene composite structure catalyst after post-processing.

In some embodiments, the post-processing includes filtration, washing with deionized water, and washing three times.

In some embodiments, the MXene is a Group IIIB-VIB metal carbide.

In some embodiments, the MXene is one of Mo _{2 CTx} , Ti ₃ C ₂ Tx, V ₂ CTx, Nb ₂ CTx and Cr ₂ CTx. Preferably, the MXene is Mo _{2 CTx} or Ti ₃ C ₂ Tx.

The etched A-site metal is all Al or G.

In some embodiments, the preparation method of MXene includes: ultrasonically treating the precursor MAX in an etching solution, causing an etching reaction, and washing and drying to obtain MXene.

When MXene is Mo ₂ CT _x , its precursor MAX is Mo ₂ Al ₂ C or Mo ₂ Ga ₂ C;

When MXene is Ti ₃ C ₂ Tx, its precursor MAX is Ti ₃ AlC ₂ or Ti ₃ GaC ₂ ;

When MXene is V ₂ CTx, its precursor MAX is V ₂ AlC or V ₂ GaC;

When MXene is Nb ₂ CTx, its precursor MAX is Nb ₂ AlC or Nb ₂ GaC;

When MXene is Cr ₂ CTx, its precursor MAX is Cr ₂ AlC/Cr ₂ GaC.

In some embodiments, the etching solution is a mixed solution of hydrochloric acid and ammonium fluoride, the concentration of the hydrochloric acid is 30~60wt%, and the mass ratio of the ammonium fluoride to the MAX is 1:1;

And/or, the ultrasonic treatment time is 30~60 minutes;

And/or, the temperature of the etching reaction is 140°C~160°C, and the time of the etching reaction is 12-24 h.

Ammonium fluoride and hydrochloric acid indirectly form HF, which is used to etch the substrate. Compared with directly using HF for etching, the reaction is more stable and safer.

In some embodiments, the volume ratio of the mass of urea to water in the urea aqueous solution in step S1 is (300~400) mg/(200~300) ml;

And/or, the concentration of chloroplatinic acid in step S1 is 0.05M;

And/or, the stirring in step S1 is mechanical stirring, and the mechanical stirring time is 3 to 4 hours; or, the stirring in step S1 is ultrasonic stirring, and the ultrasonic stirring time is 30 to 60 minutes;

And/or, the heating temperature in step S1 is 90~100°C, and the heating time is 1~2h;

And/or, the volume ratio of the ethylene glycol and the mixed solution in step S2 is 1:1~1:1.5;

And/or, the mixing and stirring in step S2 is mechanical stirring, and the mechanical stirring time is 3 to 4 hours; or, the mixing and stirring in step S2 is ultrasonic stirring, and the ultrasonic stirring time is 30 to 60 minutes;

And/or, the heating temperature in step S2 is 120~130°C, and the heating time is 1~2h;

And/or, the time for continuing stirring after heating in step S2 is 12 to 14 hours.

Above 90°C, urea is hydrolyzed in chloroplatinic acid solution to produce OH ^- , which is evenly distributed in the solution, thereby avoiding the sudden increase in pH and the formation of Pt hydroxide precipitation; controlling the temperature not to exceed 100° ^C is In order to reduce the waste of resources, at the same time, the hydrolysis reaction can be carried out slowly.

Due to the presence of ethylene glycol, acetaldehyde is generated when the temperature exceeds 100°C, which can reduce the high-priced Pt compounds that have been formed to form Pt metal particles. If the temperature does not reach 100°C, the reducing agent cannot effectively act and the temperature is too high. High makes the reaction rate too fast and causes the aggregation of Pt particles.

The third aspect of the present invention provides the above-mentioned synthetic supported Pt-MXene composite structure catalyst or the synthetic supported Pt-MXene composite structure catalyst prepared by the above-mentioned preparation method as a proton exchange membrane fuel cell oxygen reduction catalyst, hydroelectric oxygen desorption catalyst or carbon dioxide Applications of electroreduction catalysts.

Compared with the existing technology, the technical effects achieved by the present invention are as follows:

(1) The synthetic supported Pt-MXene structure single-atom platinum catalyst of the present invention adopts the ethylene glycol reduction method (wet chemical method), and selects MXene two-dimensional materials such as Mo ₂ CT _x and Ti ₃ C ₂ T _x as the two-dimensional carrier. and co-catalyst, after the reaction, the surface of the MXene carrier is not only loaded with 0-valent platinum metal particles, but also loaded with Pt ²⁺ , of which 0-valent platinum metal particles can reach more than 70%. On the one hand, the strong interface interaction between the MXene carrier and the metal is used , to obtain uniformly dispersed platinum nanoparticles. The size of platinum particles loaded on the surface of MXene obtained through characterization of synthetic materials can reach less than 2nm, and the catalytic activity of platinum is improved by the electronic coupling effect of bimetals; on the other hand, Pt ²⁺ and Platinum zero-valent metal atoms have strong interfacial interactions, which is beneficial to improving the stability and dispersion of the catalyst.

(2) The present invention uses catalyst materials prepared by reduction. Compared with traditional atomic layer deposition and other processes, this process is simpler, the synthesis cycle is short, and the reaction temperature is lower than the CVD synthesis method, which avoids This waste of resources also improves the safety of the experiment.

(3) The urea and ethylene glycol reduction method used in the present invention has not been mentioned in the MXene-TM synthesis method in the prior art. The uniform nanoparticle distribution and good conductive synergy of the synthesized Pt-MXene catalyst are utilized. , using the unique chemical structure of the two-dimensional high surface of two-dimensional materials such as Ti ₃ C ₂ T _x and Mo _{2 CT} It is found that the surface morphology of the synthesized Pt/MXene is close to single-atom level dispersion, which can reach less than 2 nm, achieving a stable platinum catalytic structure, which is beneficial to improving the catalytic performance of electrocatalysts.

(4) The wet chemical synthesis method adopted in the present invention has the advantages of simple process, low cost, low reaction temperature, safety and reliability, and is convenient for large-scale industrial production. The preparation process of synthesizing MXene is simpler and safer than the HF etching method; the present invention The experimental method is also suitable for the preparation of single-atom structures of non-noble metal catalysts on MXene substrates, and can be used more widely.

Description of the drawings

Figure 1 is an SEM image of the Mo ₂ CT _x two-dimensional material prepared after etching in Example 1 of the present invention;

Figure 2 is the XRD characterization diagram of Mo ₂ CT _x after etching and the XRD diagram of Pt/Mo ₂ CT _x composite material in Example 1 of the present invention;

Figure 3 is an XPS chart of the Pt/Mo ₂ CT _x composite material in Example 1 of the present invention, in which (a) is the full spectrum and (b) is the split-peak spectrum of platinum;

Figure 4 is the TEM, EDS pictures and particle size distribution diagram of the Pt/Mo ₂ CT _x composite material in Example 1 of the present invention, where (a) and (c) are the TEM characterization pictures of Pt/Mo ₂ CT _x , (b ) is the EDS characterization diagram of Pt/Mo ₂ CT _x , (d) is the particle size distribution diagram of Pt/Mo ₂ CT _x ;

Figure 5 is the TEM and EDS images of the Pt/Mo ₂ CT _x composite material in Example 2 of the present invention, where (a) is the TEM characterization image of Pt/Mo ₂ CT _x , and (b) is the Pt/Mo ₂ CT _x EDS characterization diagram;

Figure 6 shows the TEM, EDS and particle size distribution diagrams of the Pt/Ti ₃ C ₂ T _x composite material in Example 3 of the present invention, where (a) is the TEM characterization diagram of Pt/Ti ₃ C ₂ T _x , and (b) is the EDS characterization diagram of Pt/Ti ₃ C ₂ T _x , (c) is the particle size distribution diagram of Pt/Ti ₃ C ₂ T _x ;

Figure 7 is a LSV comparison chart in the electrochemical performance test of Pt/Mo ₂ CT _x composite materials, Mo ₂ CT _X and Pt/C prepared in Example 1 and Example 2 of the invention;

Figure 8 is the SEM and EDS characterization images of the composite material prepared in Comparative Example 1 of the present invention, where (a) is the SEM image and (b) is the EDS image;

Figure 9 is an EDS characterization diagram of the composite material prepared in Comparative Example 2 of the present invention, where (a) is the EDS diagram of the composite material, and (b) is the EDS diagram of the Pt element in the composite material;

Figure 10 is a TEM image of the composite material prepared in Comparative Example 3 of the present invention.

Detailed ways

The technical solutions of the present invention will be described below through specific embodiments in conjunction with the accompanying drawings. It should be understood that the mention of one or more steps in the present invention does not exclude the existence of other methods and steps before and after the combination step, or that other methods and steps can be inserted between these explicitly mentioned steps. It should also be understood that these examples are merely illustrative of the invention and are not intended to limit the scope of the invention. Unless otherwise stated, the numbering of each method step is only for the purpose of identifying each method step, and does not limit the order of each method or limit the implementation scope of the present invention. Changes or adjustments in their relative relationships will not change the technical content without substantial changes. Under the conditions, it can also be regarded as the implementable scope of the present invention.

There are no specific restrictions on the sources of the raw materials and instruments used in the examples. They can be purchased in the market or prepared according to conventional methods well known to those skilled in the art.

In some embodiments, a synthetic supported Pt-MXene composite structure catalyst and preparation method include:

Step 1: Dissolve 300~400 mg of urea in 200~300 mL of deionized water, add MXene to the solution, and sonicate for 30~40 minutes. Urea is used to slowly adjust the pH value of the solution to assist deposition. Above 90°C, urea is hydrolyzed in the platinum acid solution to produce OH ^- , and OH ^- is evenly distributed in the solution, thus avoiding the sudden rise in pH and the formation of Pt hydroxide. precipitation of matter.

Step 2: Add the chloroplatinic acid solution to the mixed solution in step 1, stir for 3 to 4 hours, then heat the mixture at 90 to 100°C for 1 to 2 hours, and cool to room temperature to obtain a mixed solution.

Step 3: Add 200~230 ml of ethylene glycol to the mixed solution that has been cooled to room temperature in Step 2, stir for 3~4 hours, heat at 120~130°C for 1 hour, and then stir for 10~12 hours. Due to the presence of ethylene glycol, acetaldehyde is generated when the temperature exceeds 100 degrees Celsius, which can reduce the Pt compounds that have been formed to form Pt metal particles. From the XPS picture in the following figure, you can clearly see the generation of Pt ⁰ metal particles and Pt ²⁺ . In this step, if the temperature does not reach 100°C, the reducing agent cannot effectively act. If the temperature is too high, the reaction rate will be too fast, resulting in the aggregation of Pt particles.

Step 4: Filter, wash, and dry at 60~80°C for 12~14 hours to obtain a synthetic supported Pt-MXene composite platinum catalyst.

Example 1: Pt/Mo ₂ CT _x

(1) Preparation of MXene:

Ultrasonically mix 2 g of ammonium fluoride and 40 mL of 6M hydrochloric acid solution (11.8 mol/L) for 30 minutes to obtain an etching solution; then immerse 2 g of MAX (Mo ₂ Ga ₂ C) into the etching solution, and then mix The solution was added to a Teflon-lined stainless steel reactor with a capacity of 100 ml, heated to 140°C, continued heating for 24 h, and finally cooled to room temperature. The mixed solution was washed and centrifuged with deionized water until the pH value reached 6, then washed three times with ethanol, and finally the obtained powder was dried at 60°C for 12 h to obtain Mo ₂ CT _x two-dimensional material.

(2) Preparation of Pt/Mo ₂ CT _x

Dissolve 300mg urea in 200mL deionized water, add 60mg Mo ₂ CT _x to the solution, and sonicate for 30 minutes. 5mL of 0.05M H ₂ PtCl ₆ ·6H ₂ O was added to the solution (the molar ratio of chloroplatinic acid and Mo _{2 CT} room temperature. Add 200 ml of ethylene glycol to the solution, stir for 3 hours, heat at 120°C for 1 hour, and then stir for 12 hours. Filter, wash, and dry at 80°C for 12 hours to obtain a Pt/Mo ₂ CT _x composite material. The particle size distribution of platinum nanoparticles is 2-5 nm.

Example 2: Pt/Mo ₂ CT _x

In this example, the added amount of 0.05 MH ₂ PtCl ₆ ·6H ₂ O is 1 ml (the molar ratio of chloroplatinic acid and Mo ₂ CT _x is 1:5), and the others are the same as in Example 1. A Pt/Mo ₂ CT _x composite material is obtained. Pt metal particles are evenly dispersed at the atomic level on the surface of Mo ₂ CTx, and the particle size can reach less than 2 nm.

Example 3: Preparation of Pt/Ti ₃ C _{2 Tx}

(1) Preparation of MXene:

Ultrasonically mix 2 g of ammonium fluoride and 40 mL of 6M hydrochloric acid solution (11.8 mol/L) for 30 minutes to obtain an etching solution; then immerse 2 g of MAX (Ti ₃ AlC ₂ ) into the etching solution, and then mix the mixed solution Add it to a Teflon-lined stainless steel reactor with a capacity of 100 ml, raise the temperature to 140°C, continue heating for 24 h, and finally cool to room temperature. The mixed solution was washed and centrifuged with deionized water until the pH value reached 6, then washed three times with ethanol, and finally the obtained powder was dried at 60°C for 12 h to obtain Ti ₃ C ₂ T _x two-dimensional material.

(2) Preparation of Pt/Ti ₃ C ₂ T _x

Dissolve 600 mg of urea in 400 mL of deionized water, add 65 mg of Ti ₃ C ₂ T _x to the solution, and sonicate for 30 minutes. 5 mL 0.05MH ₂ PtCl ₆ ·6H ₂ O was added to the solution, stirred for 3 h, then the mixture was heated to 90 °C, heated for 1 h, and cooled to room temperature. 200 ml of ethylene glycol was added to the solution, stirred for 3 h, heated at 120°C for 1 h, and then stirred for 12 h. Filter, wash, and dry at 80°C for 12 hours to obtain Pt/Ti ₃ C ₂ T _x composite material. The particle size distribution of Pt nanoparticles is 2-5nm.

Product Characterization and Analysis

(1) SEM analysis of Mo ₂ CT _x two-dimensional material in Example 1

SEM analysis was performed on the Mo ₂ CT _x two-dimensional material prepared in Example 1. As shown in Figure 1, it can be seen that the etched Mo ₂ CT _x is multi-layered, which can increase the contact area of the catalyst. , improve the catalytic activity of the catalyst.

(2) XRD analysis of Mo ₂ CTx and Pt/Mo ₂ CT _x composite materials in Example 1

_{XRD analysis} was performed on the Mo _{2 CT} The Mo ₂ CTx two-dimensional material is obtained by etching. After reduction with ethylene glycol, Pt nanoparticles are effectively attached to the surface of Mo _{2 CTx} .

(3) XPS, TEM, EDS and particle size distribution analysis of the Pt/Mo ₂ CT _x composite material in Example 1

As shown in Figure 3, it can be clearly seen in the XPS characterization chart that the 0-valent metal particles of Pt account for more than 70% of the total Pt compounds, and there are Pt ²⁺ ; as can be seen from Figure 4, it can be clearly seen that Single-atom Pt is deposited on the surface of Mo ₂ CT _x and is evenly distributed, with the nanoparticle size being about 2nm.

(4) TEM and EDS analysis of Pt/Mo ₂ CT _x composite material in Example 2

As shown in Figure 5, it can be clearly seen from the figure that Pt is evenly distributed in the form of atomically dispersed Pt nanoparticles on the surface of Mo ₂ CT _x , and the size of the Pt particles is below 2 nm.

(5) TEM, EDS and particle size distribution analysis of the Pt/Ti ₃ C ₂ T _x composite material in Example 3

As shown in Figure 6, it can be clearly seen from the figure that Pt particles of about 2 nm are evenly distributed on the surface of Ti ₃ C ₂ Tx, which proves that the synthesis method provided by the present invention is applicable to a variety of MXene substrates.

(6) Electrochemical performance test of Pt/Mo ₂ CT _x composite materials in Example 1 and Example 2

Oxygen-saturated 0.1 M KOH electrolyte was used, the reference electrode was a mercury oxide electrode, and the carbon rod was the counter electrode. Mix 2 mg Ketjen Black, 20 mg sample, 260 μL isopropyl alcohol, 200 μL ethanol and 40 μL 5% Nafion solution together, sonicate in an ice bath for 40 min, take 10 μL catalyst ink, and spin-coat it on the glassy carbon electrode. A catalyst film was obtained. Rotating disk electrodes were then used for electrochemical performance testing. The obtained LSV diagram is shown in Figure 7. The starting potential and half-wave potential of the Pt/Mo ₂ CT _x composite material prepared in Example 1 are 1.04V and 0.87V respectively, which is better than the commercial platinum carbon Pt electrode and has good ORR (electrocatalytic oxygen reduction reaction) catalytic effect.

Comparative example 1

The difference between Comparative Example 1 and Example 1 is that no urea was added, and the rest is the same as Example 1.

SEM characterization and EDS characterization were performed on the composite materials prepared in the comparative example. As shown in Figure 8, it can be seen that the deposition effect of precious metals is very unsatisfactory. Pt particles gather together and the deposition amount is very small. The surface content of Pt is as low as only 3 %.

Comparative example 2

The difference between Comparative Example 2 and Example 1 is that ethylene glycol was not added, and the others were the same as Example 1.

The composite material prepared in the comparative example was characterized by SEM and EDS. As shown in Figure 9, it can be seen that the particle size distribution of Pt metal particles deposited on the MXene surface is relatively uneven, and there are some larger nanoparticles.

Comparative example 3

The difference between Comparative Example 3 and Example 1 is that no ethylene glycol was added, NaBH ₄ reducing agent was added, and the others were the same as Example 1.

After testing, the particles of the composite material prepared in the comparative example were larger and unevenly distributed. The TEM image of the composite material prepared in this comparative example is shown in Figure 10.

The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and illustration. These descriptions are not intended to limit the invention to the precise form disclosed, and obviously many modifications and variations are possible in light of the above teachings. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and its practical application, thereby enabling others skilled in the art to make and utilize various exemplary embodiments of the invention and various different applications. Choice and change. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims (10)

1. A synthetic supported Pt-MXene composite structure catalyst, characterized in that the catalyst uses MXene as a carrier and platinum as an active material. The platinum is evenly dispersed on the surface of the MXene, and the platinum includes zero-valent platinum. Metal particles and Pt ²⁺ . 2. The synthetic supported Pt-MXene composite structure catalyst according to claim 1, characterized in that the particle size of the zero-valent platinum metal particles is 1~5nm; And/or, the 0-valent platinum metal particles on the surface of the MXene account for more than 70% of the total Pt content. 3. The synthetic supported Pt-MXene composite structure catalyst according to claim 1, characterized in that the particle size of the zero-valent platinum metal particles can reach less than 2 nm. 4. The preparation method of synthetic supported Pt-MXene composite structure catalyst according to claim 1, characterized in that the preparation method adopts ethylene glycol reduction impregnation method, including: Step S1: Add MXene to the urea aqueous solution, mix evenly with ultrasonic, add chloroplatinic acid, stir and mix, then heat the reaction, cool to room temperature after the reaction, and obtain a mixed solution; Step S2: Add ethylene glycol to the mixed solution obtained in step S1, mix and stir, then heat, continue stirring after heating, and obtain a synthetic supported Pt-MXene composite structure catalyst after post-processing. 5. The preparation method according to claim 4, characterized in that the MXene is a Group IIIB-VIB metal carbide. 6. The preparation method according to claim 4, characterized in that the MXene is one of Mo _{2 CTx} , Ti ₃ C ₂ Tx, V ₂ CTx, Nb ₂ CTx and Cr ₂ CTx. 7. The preparation method according to claim 4, characterized in that the preparation method of MXene includes: ultrasonically treating the precursor MAX in an etching solution, causing an etching reaction, and washing and drying to obtain MXene. 8. The preparation method according to claim 7, characterized in that the etching solution is a mixed solution of hydrochloric acid and ammonium fluoride, the concentration of the hydrochloric acid is 30~60wt%, the ammonium fluoride and the The mass ratio of MAX is 1:1; And/or, the ultrasonic treatment time is 30~60 minutes; And/or, the temperature of the etching reaction is 140°C~160°C, and the time of the etching reaction is 12-24 h. 9. The preparation method according to claim 4, characterized in that the volume ratio of the mass of urea in the urea aqueous solution to water in step S1 is (300~400) mg/(200~300) ml; And/or, the concentration of chloroplatinic acid in step S1 is 0.05M; And/or, the stirring in step S1 is mechanical stirring, and the mechanical stirring time is 3 to 4 hours; or, the stirring in step S1 is ultrasonic stirring, and the ultrasonic stirring time is 30 to 60 minutes; And/or, the heating temperature in step S1 is 90~100°C, and the heating time is 1~2h; And/or, the volume ratio of the ethylene glycol and the mixed solution in step S2 is 1:1~1:1.5; And/or, the mixing and stirring in step S2 is mechanical stirring, and the mechanical stirring time is 3 to 4 hours; or, the mixing and stirring in step S2 is ultrasonic stirring, and the ultrasonic stirring time is 30 to 60 minutes; And/or, the heating temperature in step S2 is 120~130°C, and the heating time is 1~2h; And/or, the time for continuing stirring after heating in step S2 is 12 to 14 hours. 10. A synthetic supported Pt-MXene composite structure catalyst according to any one of claims 1-3 or a synthetic supported Pt-MXene composite structure catalyst prepared according to the preparation method according to any one of claims 4-9 Application as proton exchange membrane fuel cell oxygen reduction catalyst, water electrolysis oxygen catalyst or carbon dioxide electroreduction catalyst.