A pt / c catalyst of surface-doped stable metal g, and a preparation method and application thereof

Abstract

The application discloses a Pt / C catalyst doped with a surface stability metal G, a preparation method and application thereof, and aims to solve the technical problems of poor catalytic activity and poor adaptability of the existing Pt / C catalyst. In the Pt / C catalyst doped with the surface stability metal G, G atoms are uniformly distributed on the surface of Pt particles, and G is one or more of Au, Mo and W; the mass percentage of Pt in the catalyst is 10% to 30%. The catalyst is obtained by impregnating a salt solution of the stability metal G, evaporating and adsorbing on the surface of the Pt / C catalyst, and reducing by low-temperature annealing. The mass activity of the catalyst is 0.131 to 0.168 mA / μg Pt , and the half-wave potential is 0.896 to 0.905 V. After being aged for 30000 cycles, the peak power density value of the fuel cell assembled by the catalyst only decreases by 0.6 W, and the stability is good. The catalyst can be applied to the field of fuel cells.

Description

TECHNICAL FIELD

[0001] The present application relates to a surface-doped Pt / C catalyst and a preparation method and application thereof, and belongs to the field of new energy materials. BACKGROUND

[0002] Pt / C materials are widely used as cathode (ORR) catalysts for proton exchange membrane fuel cells due to their good catalytic performance for oxygen reduction reactions. However, current commercial Pt / C catalysts have problems such as insufficient activity and durability in long-term operation under harsh reaction conditions, and the future development direction will focus on improving durability as the primary goal.

[0003] Current commercial Pt / C catalysts are mainly high-load, and the cost of Pt is high, accounting for half of the cost of proton exchange membrane fuel cells, and the catalyst is prone to deactivation and aging during operation, causing the growth of Pt nanoparticles in the catalyst, resulting in a decrease in electrochemical active area and a decrease in fuel cell performance. SUMMARY

[0004] The present application is to solve the technical problems of poor catalytic activity and insufficient adaptability of existing Pt / C catalysts, and to provide a Pt / C catalyst surface-doped with a stability metal G and a preparation method and application thereof. The salt solution of the stability metal G (G = Au, Mo or W) is impregnated and evaporated to be adsorbed on the surface of the Pt / C catalyst, and a Pt-G / C catalyst is obtained by low-temperature annealing reduction. The activity and stability of the catalyst are significantly higher than those of the 20% Pt / C catalyst, and the surface-doped Pt-G / C catalyst has applicability in fuel cells.

[0005] The Pt / C catalyst surface-doped with the stability metal G of the present application has G atoms uniformly distributed on the surface of Pt particles, and G is one or several of Au, Mo and W; the mass percentage of Pt in the catalyst is 10% to 30%.

[0006] Further, the molar ratio of G atoms to Pt atoms is 1:(100-10). Since the catalytic activity of Au, Mo and W elements is relatively poor, too high a content can easily cause a decrease in catalytic activity. In the surface-doped Pt / C catalyst of G element, the molar ratio of G atoms to Pt atoms is 1:(100-10), which improves the stability of the catalyst while reducing the cost.

[0007] The preparation method of the above-mentioned Pt / C catalyst surface-doped with the stability metal G is carried out according to the following steps:

[0008] I. Preparation of Pt / C catalyst by microwave reduction method;

[0009] II. Adsorption of G metal salt: after the Pt / C catalyst is wetted, it is put into the dispersion solution, and ultrasonic stirring is performed until the catalyst is uniformly dispersed, to obtain a mixed solution A; then a solution of a stable metal G salt is added dropwise into the mixed solution A, and after the dropwise addition is completed, a mixed solution B is obtained; the mixed solution B is subjected to ultrasonic treatment for 0.5-2 h, and then is stirred at room temperature for 0.5-2 h, so that the mixed solution is uniformly dispersed; then the mixed solution B is evaporated under water bath conditions, to obtain a precursor;

[0010] III. Annealing reduction to prepare Pt-G / C: the precursor is placed in a high-temperature furnace, and is heated to 200-600℃ in a reducing atmosphere for 4-10 h for annealing, and is cooled to room temperature, and is uniformly ground, to obtain a Pt / C catalyst doped with a stable metal G on the surface, which is denoted as Pt-G / C.

[0011] Further, the specific method for preparing the Pt / C by the microwave reduction method is as follows: the carbon carrier is added into a dispersion liquid and is uniformly dispersed, and a chloroplatinic acid solution is added, and after stirring is uniformly performed, the pH of the mixed solution is adjusted to be alkaline; the Pt particles are reduced by using a microwave, and after natural cooling, the pH is adjusted to be acidic and stirring is performed for 12-24 h, and after suction filtration and washing, vacuum drying is performed, to obtain a Pt / C catalyst; the dispersion liquid is one or several of water, ethanol, methanol and isopropyl alcohol; the carbon powder is XC-72, ECP-600JD or BP-2000.

[0012] Further, the dispersion solution in step II is one or several of water, ethanol, methanol and isopropyl alcohol.

[0013] Further, the solution of the G metal salt in step II is prepared by dissolving chloroauric acid, gold trichloride, potassium chloroaurate, molybdate, molybdenum pentachloride, tungstate or tungsten hexachloride in the dispersion solution.

[0014] Further, in the mixed solution B in step II, the concentration of the Pt / C is 0.5-2 g / L, and the concentration of the stable metal G salt is 0.00025-0.001 mol / L.

[0015] Further, the reducing gas in step III is H2 / N2 mixed gas or H2 / Ar mixed gas, and the volume ratio of H2 in the mixed gas is 3%-15%.

[0016] The application of the above-mentioned Pt / C catalyst doped with a stable metal G on the surface is that the catalyst is used in the cathode oxygen reduction reaction (ORR) of a fuel cell.

[0017] The present application effectively improves the stability of Pt / C catalyst by doping with stable metal G (G=Au, Mo, W). The stable metal G has good electrochemical stability, and is introduced into the electrocatalyst to improve the stability of the electrocatalyst. Meanwhile, since the ORR catalytic activity of Au and Mo elements is poor, the present application controls the addition amount of the stable metal G to avoid the reduction of the catalytic activity caused by the coverage of the active sites of Pt in the catalyst. In addition, the elements such as Au, Mo and W have high cost, and if the doping amount is too much, the cost of the catalyst will be significantly affected. The present application reduces the Pt loading while maintaining the activity of the catalyst, and modifies the catalyst by using the stable metal G to prepare a Pt / C catalyst with good performance, which has the surface doped with the stable metal G. The mass activity of the catalyst is 0.131-0.168 mA / μg Pt , and the half-wave potential reaches 0.896-0.905 V. After being aged for 30000 cycles, the peak power density value of the fuel cell assembled with the catalyst only decreases by 0.6 W, and the decrease rate is 32%, so the catalyst has good stability.

[0018] The advantages of the present application are as follows:

[0019] (1) The present application dopes the stable metal on the surface of the Pt / C catalyst. First, the metal salt is adsorbed on the surface of the Pt / C catalyst by the method of immersion and evaporation, and the G salt is reduced to G metal under a reducing atmosphere by low-temperature annealing. With continuous heating, the G metal is gradually and uniformly distributed on the surface of the Pt particles to obtain the Pt-G / C catalyst. The preparation method is simple and easy to implement, and is suitable for industrial production.

[0020] (2) The doping amount of the G metal in the present application is very low, which avoids the problems of activity reduction and cost increase caused by the doping of a large amount of G metal.

[0021] (3) The catalyst prepared in the present application has high electrocatalytic activity and durability for oxygen reduction reaction in an acidic medium, and has good applicability in a fuel cell, so that the catalyst also has excellent performance in the fuel cell. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a TEM image of the Pt / C catalyst with the surface doped with the stable metal Au prepared in Example 1;

[0023] Figure 2 is a spherical aberration-corrected transmission electron microscope image of the Pt / C catalyst with the surface doped with the stable metal Au prepared in Example 1;

[0024] Figure 3 is an EDS line scanning element distribution map of the spherical aberration-corrected transmission electron microscope of the Pt / C catalyst with the surface doped with the stable metal Au prepared in Example 1;

[0025] Figure 4 Pt-Au prepared in Example 1 0.05 Pt-Au prepared in Example 2 0.05 Pt-Au prepared in Example 3 0.05 XRD pattern of Pt / C-400°C 2h catalyst;

[0026] Figure 5 Pt-Mo prepared in Example 4 0.05 Pt-W prepared in Example 5 0.1 XRD pattern of Pt / C-400°C 6h catalyst;

[0027] Figure 6 Pt-Au prepared in Example 1 0.05 Pt-Au prepared in Example 2 0.05 Pt-Au prepared in Example 3 0.03 Pt-Mo prepared in Example 4 0.05 Pt-W prepared in Example 5 0.1 Pt-Au prepared in Comparative Example 1 and 20% Pt / C catalyst prepared in Step 1 of Example 1 0.05 ORR polarization plot of Pt / C-400°C 2h catalyst;

[0028] Figure 7 Pt-Au prepared in Example 1 0.05 Pt-Au prepared in Example 2 0.05 Pt-Au prepared in Example 3 0.03 Pt-Mo prepared in Example 4 0.05 Pt-W prepared in Example 5 0.1 Pt-Au prepared in Comparative Example 1 and 20% Pt / C catalyst prepared in Step 1 of Example 1 0.05 Mass activity plot of Pt / C-400°C 2h catalyst;

[0029] Figure 8 Pt-Au prepared in Example 1 0.05 ORR polarization plot of Pt / C-400°C 6h catalyst and 20% Pt / C catalyst prepared in Step 1 of Example 1 before and after aging;

[0030] Figure 9 It is the Pt-Au prepared in Example 1 0.05 / C-400℃6h catalyst and the 20% Pt / C catalyst prepared in step one of Example 1 before and after aging; mass ratio activity diagram of catalyst before and after aging;

[0031] Figure 10 It is the Pt-Au prepared in Example 1 0.05 Polarization diagrams of fuel cells before and after aging of the catalyst prepared at -400℃ for 6 hours and the 20% Pt / C catalyst prepared in step one of Example 1. Detailed Implementation

[0032] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments, but it is not limited thereto. Any modifications or equivalent substitutions to the technical solution of the present invention that do not depart from the spirit and scope of the technical solution of the present invention should be covered within the protection scope of the present invention.

[0033] Example 1: The preparation method of the Pt / C catalyst with surface-doped stable metal Au in this example is carried out according to the following steps:

[0034] I. Preparation of Pt / C by Microwave Reduction: 48 mg of ECP-600ID carbon support was dispersed in 40 ml of ethylene glycol, and 1.26 ml of 0.0486 mol / L chloroplatinic acid solution was added. The mixture was sonicated for 1 h, stirred until homogeneous, and then treated with 1 mol / L... -1 The pH of the mixture was adjusted to 12 using NaOH-ethylene glycol solution, and nitrogen gas was introduced to remove dissolved air and protect the solution. The mixture was then microwaved for 80 seconds. After natural cooling, the pH was adjusted to 2 using nitric acid-ethylene glycol solution and stirred for 8 hours. After filtration and washing three times, the mixture was vacuum dried at 80°C for 8 hours and then ground until homogeneous to obtain the Pt / C catalyst, designated as the 20% Pt / C catalyst.

[0035] II. Adsorption of Au: 60 mg of 20% Pt / C catalyst was moistened and dispersed in 60 ml of ethanol. The mixture was sonicated for 30 min and stirred until the catalyst was uniformly dispersed, yielding mixed solution A. Then, 0.344 ml of 1.7429 mg of [a specific catalyst] was added dropwise to mixed solution A. Au After adding HAuCl4 ethanol solution at a concentration of / ml, a mixed solution B was obtained. The mixed solution B was ultrasonically treated for 1 hour, and then evaporated to dryness in a water bath at 60℃. The solution was then ground evenly to obtain the precursor.

[0036] III. Preparation of Pt-Au by Annealing and Reduction 0.05 / C: The precursor of step two was placed in a high temperature furnace, annealed in H2-Ar reducing atmosphere, heated to 400°C for 6h, cooled to room temperature, and grinded to uniformity to obtain Au surface doped Pt / C catalyst, noted as Pt-Au 0.05 / C-400°C for 6h, the mass percentage of Pt in the catalyst was 20%, and the atomic ratio of Pt to Au was 20:1.

[0037] The Pt-Au catalyst prepared in Example 1 was used as the catalyst in the following experiments. 0.05 TEM of the / C-400°C for 6h catalyst is shown in Fig. 1, and the particle size distribution is shown in Fig. 2. Figure 1 As can be seen from Fig. 1, the Pt particles are uniformly distributed on the carbon carrier. Figure 1 As can be seen from Fig. 2, the particle size distribution is narrow and the particle size is about 2.5nm.

[0038] The Pt-Au catalyst prepared in Example 1 was used as the catalyst in the following experiments. 0.05 The spherical aberration-corrected transmission electron microscopy (STEM) of the / C-400°C for 6h catalyst is shown in Fig. 3, and the EDS line scanning element distribution map is shown in Fig. 4. Figure 2 As can be seen from Fig. 3, the particle size distribution is narrow and the particle size is about 2.5nm. Figure 2 As can be seen from Fig. 4, the Au element is mainly distributed on the surface of the Pt particles. Figure 3 The Pt-Au catalyst prepared in Example 1 was used as the catalyst in the following experiments. 0.05 The spherical aberration-corrected transmission electron microscopy (STEM) of the / C-400°C for 6h catalyst is shown in Fig. 3, and the EDS line scanning element distribution map is shown in Fig. 4.

[0039] Example 2: The difference between this example and Example 1 is that the annealing temperature in step three is 600°C and the annealing time is 4h, and the other steps and parameters are the same as those in Example 1, and the obtained catalyst is noted as Pt-Au 0.05 / C-600°C for 4h.

[0040] Comparative Example 1: The difference between this comparative example and Example 1 is that the annealing temperature in step three is 400°C and the annealing time is 2h, and the other steps and parameters are the same as those in Example 1, and the obtained catalyst is noted as Pt-Au 0.05 / C-400°C for 2h.

[0041] The Pt-Au catalyst prepared in Example 1 was used as the catalyst in the following experiments. 0.05 The Pt-Au catalyst prepared in Example 2 was used as the catalyst in the following experiments. 0.05 The Pt-Au catalyst prepared in Example 1 was used as the catalyst in the following experiments. 0.05 The XRD spectrum of the / C-400°C for 2h catalyst is shown in Fig. 5, and the particle size distribution is shown in Fig. 6. Figure 4 As can be seen from Fig. 5, the particle size distribution is narrow and the particle size is about 2.5nm. Figure 4It can be seen that the heat treatment time of Comparative Example 1 was relatively short, and obvious PtAu alloy peaks were observed in XRD. However, the heating times of Examples 1 and 2 were relatively long, and no PtAu alloy peaks were observed in XRD. This proves that the Au element is uniformly distributed on the surface of the Pt particles and does not affect the crystal form of the Pt particles.

[0042] Example 3: The preparation method of the Pt / C catalyst with surface-doped stable metal Au in this example is carried out according to the following steps:

[0043] I. Preparation of Pt / C by Microwave Reduction: 48 mg of ECP-600JD carbon support was dispersed in 40 ml of ethylene glycol solution, 1.26 ml of 0.0486 mol / L chloroplatinic acid solution was added, and the mixture was sonicated for 1 h. After stirring until homogeneous, 1 mol / L... -1 The pH of the mixture was adjusted to 12 with NaOH-ethylene glycol solution, and nitrogen gas was introduced to remove dissolved air from the solution to protect it. The mixture was then microwaved for 80 seconds. After natural cooling, the pH of the mixture was adjusted to 2 with nitric acid-ethylene glycol solution and stirred for 8 hours. After filtration and washing three times, it was vacuum dried at 80°C for 8 hours and ground evenly to obtain the Pt / C catalyst.

[0044] II. Adsorption of Au: 60 mg of Pt / C catalyst was moistened and dispersed in 60 ml of ethanol. The mixture was sonicated for 30 min and stirred until the catalyst was evenly dispersed, yielding mixed solution A. Then, 0.207 ml of 1.7429 mg of Au was added dropwise to mixed solution A. Au After adding ethanol solution of HAuCl4 at a concentration of / ml, a mixed solution B was obtained. The mixed solution B was ultrasonically treated for 1 hour, and then evaporated to dryness by rotation in a water bath at 80℃. The solution was then ground evenly to obtain the precursor.

[0045] III. Preparation of Pt-Au by Annealing and Reduction 0.03 / C: The precursor from step two is placed in a high-temperature furnace and annealed at 400°C for 6 hours under a reducing atmosphere of H2-Ar (H2 volume percentage 5%). After cooling to room temperature and grinding uniformly, a Pt / C catalyst with surface-doped stable metal Au is obtained, denoted as Pt-Au. 0.03 The catalyst contains 20% Pt by mass and has an atomic ratio of 100:3 to Pt of Au.

[0046] Example 4: The preparation method of the surface-doped stable metal Mo-based Pt / C catalyst in this example is carried out according to the following steps:

[0047] I. Preparation of Pt / C by microwave reduction method: 48 mg of ECP-600JD carbon carrier was dispersed in 40 ml of ethylene glycol solution, 1.26 ml of 0.0486 mol / L chloroplatinic acid solution was added, and ultrasonic treatment was performed for 1 h. After uniform stirring, 1 mol / L NaOH-ethylene glycol solution was used to adjust the pH value of the mixed solution to 12, and nitrogen was introduced to remove the dissolved air in the solution to protect the solution. Subsequently, the mixed solution was placed in a microwave oven and microwave heating was performed for 80 s. After natural cooling, the pH value of the mixed solution was adjusted to 2 using nitric acid-ethylene glycol solution, and stirring was performed for 8 h. After suction filtration and washing for 3 times, vacuum drying was performed at a temperature of 80 °C for 8 h, and uniform grinding was performed to obtain a Pt / C catalyst; -1 NaOH-ethylene glycol solution was used to adjust the pH value of the mixed solution to 12, and nitrogen was introduced to remove the dissolved air in the solution to protect the solution. Subsequently, the mixed solution was placed in a microwave oven and microwave heating was performed for 80 s. After natural cooling, the pH value of the mixed solution was adjusted to 2 using nitric acid-ethylene glycol solution, and stirring was performed for 8 h. After suction filtration and washing for 3 times, vacuum drying was performed at a temperature of 80 °C for 8 h, and uniform grinding was performed to obtain a Pt / C catalyst;

[0048] II. Mo adsorption: After wetting 60 mg of the Pt / C catalyst, 60 ml of ethanol was added for dispersion, ultrasonic treatment was performed for 30 min, and stirring was performed until the catalyst was uniformly dispersed to obtain a mixed solution A. Then, an aqueous solution containing 0.003 mmol of sodium molybdate was added dropwise to the mixed solution A, and after the dropwise addition was completed, a mixed solution B was obtained. The mixed solution B was subjected to ultrasonic treatment for 1 h, and then the mixed solution B was rotary evaporated under the condition of a 60 °C water bath, and uniform grinding was performed to obtain a precursor;

[0049] III. Preparation of Pt-Mo / C by annealing reduction method: 0.05 The precursor of step II was placed in a high-temperature furnace, and annealing was performed under a H2-Ar reducing atmosphere (the volume percentage of H2 was 5%) at a temperature of 400 °C for 6 h. After cooling to room temperature, uniform grinding was performed to obtain a Pt / C catalyst doped with a stable metal Mo on the surface, which was recorded as Pt-Mo / C-400 °C 6 h. In the catalyst, the mass percentage of Pt was 20%, and the atomic ratio of Pt to Mo was 20:1. 0.05 / C-400 °C 6 h. In the catalyst, the mass percentage of Pt was 20%, and the atomic ratio of Pt to Mo was 20:1.

[0050] Example 5: The preparation method of the Pt / C catalyst doped with a stable metal W on the surface in the example was performed according to the following steps:

[0051] I. Preparation of Pt / C by microwave reduction method: 48 mg of ECP-600JD carbon carrier was dispersed in 40 ml of ethylene glycol solution, 1.26 ml of 0.0486 mol / L chloroplatinic acid solution was added, and ultrasonic treatment was performed for 1 h. After uniform stirring, 1 mol / L NaOH-ethylene glycol solution was used to adjust the pH value of the mixed solution to 12, and nitrogen was introduced to remove the dissolved air in the solution to protect the solution. Subsequently, the mixed solution was placed in a microwave oven and microwave heating was performed for 80 s. After natural cooling, the pH value of the mixed solution was adjusted to 2 using nitric acid-ethylene glycol solution, and stirring was performed for 8 h. After suction filtration and washing for 3 times, vacuum drying was performed at a temperature of 80 °C for 8 h, and uniform grinding was performed to obtain a Pt / C catalyst; -1 NaOH-ethylene glycol solution was used to adjust the pH value of the mixed solution to 12, and nitrogen was introduced to remove the dissolved air in the solution to protect the solution. Subsequently, the mixed solution was placed in a microwave oven and microwave heating was performed for 80 s. After natural cooling, the pH value of the mixed solution was adjusted to 2 using nitric acid-ethylene glycol solution, and stirring was performed for 8 h. After suction filtration and washing for 3 times, vacuum drying was performed at a temperature of 80 °C for 8 h, and uniform grinding was performed to obtain a Pt / C catalyst;

[0052] II. Adsorption of W: 60 mg of Pt / C catalyst was wetted and dispersed in 60 ml of ethanol, and then ultrasonically treated for 30 min. The catalyst was stirred until it was uniformly dispersed to obtain a mixed solution A. Then, an ethanol solution containing 0.006 mmol of tungstic acid was added dropwise to the mixed solution A. After the dropwise addition was completed, a mixed solution B was obtained. The mixed solution B was ultrasonically treated for 1 h, and then was rotary evaporated at 80°C under water bath conditions. The resulting product was ground to obtain a precursor;

[0053] III. Annealing and reduction to prepare Pt-W 0.1 / C: The precursor of step II was placed in a high-temperature furnace, and was annealed at 400°C for 6 h under a H2-Ar reducing atmosphere (5% by volume of H2). After cooling to room temperature, the product was ground to obtain a Pt / C catalyst doped with stable metal W on the surface, which was denoted as Pt-W. 0.1 / C-400°C for 6 h. The mass percentage of Pt in the catalyst was 20%, and the atomic ratio of Pt to W in the catalyst was 10:1.

[0054] Pt-Mo prepared in Example 4 0.05 / C-400°C for 6 h and Pt-W prepared in Example 5 0.1 The XRD spectrum of the Pt-Au / C-400°C for 6 h catalyst prepared in Example 1 is shown in Figure 5 From Figure 5 It can be seen that the Pt particle crystal form of the catalyst does not change after the addition of Mo and W elements.

[0055] Pt-Au / C-400°C for 6 h catalyst prepared in Example 1, Pt-Au / C-600°C for 4 h catalyst prepared in Example 2, Pt-Au / C-400°C for 6 h catalyst prepared in Example 3, Pt-Mo / C-400°C for 6 h catalyst prepared in Example 4, and Pt-W / C-400°C for 6 h catalyst prepared in Example 5 0.05 Pt-Au / C-400°C for 6 h catalyst prepared in Example 1, Pt-Au / C-600°C for 4 h catalyst prepared in Example 2, Pt-Au / C-400°C for 6 h catalyst prepared in Example 3, Pt-Mo / C-400°C for 6 h catalyst prepared in Example 4, and Pt-W / C-400°C for 6 h catalyst prepared in Example 5 0.05 Pt-Au / C-400°C for 6 h catalyst prepared in Example 1, Pt-Au / C-600°C for 4 h catalyst prepared in Example 2, Pt-Au / C-400°C for 6 h catalyst prepared in Example 3, Pt-Mo / C-400°C for 6 h catalyst prepared in Example 4, and Pt-W / C-400°C for 6 h catalyst prepared in Example 5 0.03 Pt-Au / C-400°C for 6 h catalyst prepared in Example 1, Pt-Au / C-600°C for 4 h catalyst prepared in Example 2, Pt-Au / C-400°C for 6 h catalyst prepared in Example 3, Pt-Mo / C-400°C for 6 h catalyst prepared in Example 4, and Pt-W / C-400°C for 6 h catalyst prepared in Example 5 0.05 Pt-Au / C-400°C for 6 h catalyst prepared in Example 1, Pt-Au / C-600°C for 4 h catalyst prepared in Example 2, Pt-Au / C-400°C for 6 h catalyst prepared in Example 3, Pt-Mo / C-400°C for 6 h catalyst prepared in Example 4, and Pt-W / C-400°C for 6 h catalyst prepared in Example 5 0.1 Pt-Au / C-400°C for 6 h catalyst prepared in Example 1, Pt-Au / C-600°C for 4 h catalyst prepared in Example 2, Pt-Au / C-400°C for 6 h catalyst prepared in Example 3, Pt-Mo / C-400°C for 6 h catalyst prepared in Example 4, and Pt-W / C-400°C for 6 h catalyst prepared in Example 5 0.05 The catalysts were prepared into electrodes, and ORR polarization tests were performed. The method for preparing the electrodes was as follows: 2.5 mg of catalyst was weighed, and then 500 μL of a dispersion liquid was added, wherein the dispersion liquid was obtained by mixing anhydrous ethanol, ultrapure water, and a nafion solution. The catalyst slurry was obtained by ultrasonic treatment for 1 h. 10 μL of the catalyst slurry was taken by a micropipette gun and dropped on a glass carbon electrode. The loading density of the catalyst on the electrode was 0.2 mg cm -2Finally, the electrodes were dried at room temperature to obtain the electrodes, and then electrochemical tests were performed. A CHI-760e electrochemical workstation was used, the test temperature was 25℃, the test system was a three-electrode system, and the electrolyte was 0.1 mol / L. -1 Using HClO4 solution, a rotating disk-to-disk glassy carbon electrode as the working electrode, a carbon rod as the counter electrode, and a reversible hydrogen electrode (RHE) as the reference electrode, the resulting ORR polarization curve is shown below. Figure 6 As shown, the mass activity graph is as follows: Figure 7 As shown in Table 1, the mass activity and half-wave potential of each catalyst are shown in Table 1.

[0056] Table 1. Mass activity and half-wave potential of the catalysts prepared in each example.

[0057] Example Product name mass activity (mA / μg Pt ) Half-wave potential (V) Example 1 Pt-Au 0.05 / C-400 °C 6h 0.168 0.905 Example 2 Pt-Au 0.05 / C-600 °C 4 h 0.135 0.896 Example 3 Pt-Au 0.03 / C-400 °C 6h 0.138 0.898 Example 4 Pt-Mo 0.05 / C-400℃6h]]> 0.165 0.903 Example 5 Pt-W 0.1 / C-400 °C 6h 0.131 0.896 Example 1 Step 1 20% Pt / C 0.085 0.881 Comparative Example 1 Pt-Au 0.05 / C-400 °C 2 h 0.115 0.891

[0058] As can be seen from Table 1, the activity of Pt / C catalysts was improved after doping with a small amount of G.

[0059] Example 1: Preparation of Pt-Au 0.05 ORR aging tests were conducted on the catalyst prepared at -400℃ for 6 hours and the 20% Pt / C catalyst prepared in step one of Example 1. The ORR polarization diagrams before and after aging are shown below. Figure 8 As shown, the Pt-Au prepared in Example 1 0.05 The mass ratio activity diagrams of the catalyst at -400℃ for 6 hours and the 20% Pt / C catalyst prepared in step one of Example 1 before and after aging are shown below. Figure 9 As shown, from Figure 8 and Figure 9 It can be seen that Pt-Au 0.05 After aging at 400℃ for 6 hours and 30,000 cycles, the mass activity of Pt / C decreased by only 6.5%, while that of 20% Pt / C decreased by 38.8% after aging for 30,000 cycles. 0.05 The stability of / C at 400℃ for 6 hours is much better than that of 20% Pt / C.

[0060] The Pt-Au prepared in Example 1 0.05 The / C-400℃6h catalyst and the 20% Pt / C catalyst prepared in step one of Example 1 were used to prepare electrodes. The method for preparing the electrodes is as follows: The catalyst was weighed and added to a dispersion, which was a mixture of isopropanol, ultrapure water, and Nafion solution. The dispersion was ultrasonically dispersed for 2 hours to obtain a dispersion. Then, the dispersion was sheared in a shear mill for 0.5 hours and transferred to a crusher for 0.5 hours to obtain a uniformly dispersed dispersion. The dispersion was added to an ultrasonic spraying machine and sprayed onto a 3×3 (cm) Nafion (ion exchange membrane) to obtain a cathode catalyst layer. The Pt loading in the cathode catalyst layer was 0.1 mg / cm². -2Pt / C catalysts were prepared according to the procedure described in Example 1. The anode catalyst layer was a commercial Pt / C with a Pt loading of 60%. The catalyst layers were assembled into a fuel cell test setup and MEA tests were performed. Figure 10 Pt-Au / C-400°C 6h catalyst prepared in Example 1 0.05 The polarization curves of the Pt / C-400°C 6h catalyst and the 20% Pt / C catalyst prepared in Example 1, step one, before and after aging are shown in Figure 2. The peak power density values of each catalyst before and after aging are shown in Table 2, calculated from the polarization curves. Figure 10 As can be seen from Figure 2 and Table 2, the Pt-Au / C-400°C 6h catalyst has a higher peak power density than the 20% Pt / C catalyst and also has better stability in the operation of the fuel cell than the 20% Pt / C catalyst. 0.05 The peak power density of the Pt-Au / C-400°C 6h catalyst is higher than that of the 20% Pt / C catalyst and its stability in the operation of the fuel cell is also better than that of the 20% Pt / C catalyst.

[0061] Table 2 Pt-Au / C-400°C 6h catalyst and 20% Pt / C catalyst peak power density values 0.05 The peak power density values of the Pt-Au / C-400°C 6h catalyst and the 20% Pt / C catalyst

[0062]

[0063] The G element in the Pt / C surface-doped stability metal G catalyst of the present application is uniformly distributed on the surface of the Pt particles in the form of atoms; the atomic radius of the G atom can change the electronic structure of the surrounding Pt atoms, improving the activity of the Pt atoms; at the same time, the G atom can also stabilize the surrounding Pt atoms, enhancing the stability of the catalyst. In addition, the Pt / C surface-doped stability metal G catalyst has good applicability in fuel cells and exhibits good performance in fuel cells.

Claims

1. A Pt / C catalyst of a surface-doped stable metal G, characterized in that, The G atoms in the catalyst are uniformly distributed on the surface of Pt particles, and G is one or more of Au, Mo and W; the mass percentage of Pt in the catalyst is 10-30%; and the molar ratio of G atoms to Pt atoms is 1:(100-20).

2. A method of preparing a Pt / C catalyst of a surface-doped stable metal G according to claim 1, characterized in that, The method is performed according to the following steps: I. Preparation of Pt / C catalyst by microwave reduction method; II. Adsorption of G metal salt: after the Pt / C catalyst is wetted, it is put into a dispersion solution, and ultrasonic stirring is performed until the catalyst is uniformly dispersed, to obtain a mixed solution A; then a solution of stable metal G salt is added dropwise into the mixed solution A, and after the dropwise addition is completed, a mixed solution B is obtained; the mixed solution B is subjected to ultrasonic treatment for 0.5-2 h, and then is stirred at room temperature for 0.5-2 h, so that the mixed solution is uniformly dispersed; Then, the mixed solution B is evaporated under water bath condition to obtain a precursor; III. Preparation of Pt-G / C by annealing reduction: the precursor is placed in a high-temperature furnace, and is heated to 200-600 DEG C in a reducing atmosphere for 4-10 h for annealing, and is cooled to room temperature, and is uniformly ground, to obtain a Pt / C catalyst doped with stable metal G on the surface, which is denoted as Pt-G / C.

3. The method of claim 2, wherein the Pt / C catalyst is prepared by the steps of: The method for preparing the Pt / C catalyst by microwave reduction method in step I is performed according to the following steps: the carbon carrier is added into a dispersion solution, a chloroplatinic acid solution is added, and after stirring is uniformly performed, the pH of the mixed solution is adjusted to be alkaline; Pt particles are reduced by using a microwave, and after natural cooling, the pH is adjusted to be acidic and stirring is performed for 12-24 h, and then the Pt / C catalyst is obtained by washing through suction filtration and vacuum drying; the dispersion solution is one or more of water, ethanol, methanol and isopropanol; and the carbon powder is XC-72, ECP-600JD or BP-2000.

4. The method of claim 2 or 3, wherein the Pt / C catalyst is prepared by the steps of: The dispersion solution in step II is one or more of water, ethanol, methanol and isopropanol.

5. The method of claim 2 or 3, wherein the Pt / C catalyst is prepared by the steps of: The solution of G metal salt in step II is prepared by dissolving chloroauric acid, gold trichloride, potassium chloroaurate, molybdate, molybdenum pentachloride, tungstate or tungsten hexachloride in the dispersion solution.

6. The method of claim 2 or 3, wherein the Pt / C catalyst is prepared by the steps of: In the mixed solution B in step II, the concentration of Pt / C is 0.5-2 g / L, and the concentration of the stable metal G salt is 0.00025-0.001 mol / L.

7. The method of claim 2 or 3, wherein the Pt / C catalyst is prepared by the steps of: The reducing gas in step III is H2 / N2 mixed gas or H2 / Ar mixed gas, and the volume percentage of H2 in the mixed gas is 3-15%.

8. Use of a surface-doped stable metal G Pt / C catalyst according to claim 1, characterized in that, The application is to use the Pt / C catalyst doped with stable metal G on the surface in the cathode oxygen reduction reaction of a fuel cell.

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