A platinum-based fuel cell catalyst and its preparation method and application

Abstract

The present invention discloses a platinum-based fuel cell catalyst, its preparation method, and application, relating to the field of fuel cell technology. The platinum-based fuel cell catalyst disclosed in the present invention includes a carrier and active particles supported on the carrier. The active particles include a core layer and a shell layer located on the surface of the core layer. The core layer is made of a platinum-based intermetallic compound (Pt3M), and the shell layer is made of metallic platinum. At least a portion of the shell layer's surface is coated with a non-metal. M is a transition metal, the non-metal is at least one of N, P, and S, and the carrier is a carbon material. Based on the mass fraction of the carrier being 100%, the mass fraction of platinum in the platinum-based fuel cell catalyst is 10% to 60%. The average particle size of the active particles is 1 nm to 5 nm. The platinum-based fuel cell catalyst provided by the present invention has excellent stability, and the active particles can be stably anchored on the carrier, exhibiting ultra-long durability even at high current densities.

Description

Technical Field

[0001] The present invention relates to the field of fuel cell technology, and in particular to a platinum-based fuel cell catalyst and a preparation method and application thereof. Background Art

[0002] Energy plays an indispensable role in human life. The energy currently used is mainly fossil energy, but fossil energy is a primary energy source with limited reserves and causes great pollution to the environment. Fuel cells, as a clean and sustainable new energy source, can directly convert hydrogen energy into electrical energy, but their slow kinetic characteristics require the addition of precious metal catalysts to promote the redox reaction. The currently commonly used platinum-based fuel cell catalysts have good activity but poor durability. In actual application, the active components in the catalyst are easily detached from the carrier, which seriously restricts the performance and life of the fuel cell. Summary of the Invention

[0003] The main purpose of the present invention is to provide a platinum-based fuel cell catalyst and its preparation method and application, so as to solve the problem of poor stability of platinum-based fuel cell catalysts in the prior art.

[0004] To achieve the above-mentioned object, according to a first aspect of the present invention, there is provided a platinum-based fuel cell catalyst, comprising a carrier and active particles supported on the carrier, the active particles comprising a core layer and a shell layer located on the surface of the core layer, the material of the core layer comprising a platinum-based intermetallic compound Pt3M, the material of the shell layer comprising metallic platinum, and at least a portion of the surface of the shell layer being wrapped by a non-metal; wherein M is a transition metal, the non-metal is at least one of N, P, and S, and the carrier is a carbon material; based on the mass fraction of the carrier being 100%, the mass fraction of the platinum element in the platinum-based fuel cell catalyst is 10% to 60%; and the average particle size of the active particles is 1 nm to 5 nm.

[0005] Furthermore, in the platinum-based fuel cell catalyst, the molar ratio of platinum element to transition metal element is 1:1 to 9:1, and the molar ratio of platinum element to non-metallic element is 3:1 to 9:1; the non-metallic element is at least one of N, P, and S.

[0006] Furthermore, the transition metal includes at least one of Mn and Co.

[0007] Furthermore, based on the mass fraction of the carrier being 100%, the mass fraction of the platinum element in the platinum-based fuel cell catalyst is 20% to 40%.

[0008] Furthermore, the electrochemical active surface area (ECSA) of the platinum-based fuel cell catalyst is 60m2 / g Pt ~90m 2 / g Pt .

[0009] According to the second aspect of the present invention, there is also provided a method for preparing the platinum-based fuel cell catalyst according to the first aspect of the present invention, comprising the following steps:

[0010] S1, mixing a platinum precursor, a transition metal precursor, a non-metallic source, and carbon powder to obtain a first mixture;

[0011] S2, calcining the first mixture in a mixture of an inert gas and a reducing gas to obtain a second mixture;

[0012] S3, acid-washing, cleaning, and drying the second mixture to obtain a platinum-based fuel cell catalyst;

[0013] Wherein, the transition metal precursor is acetylacetonate of transition metal.

[0014] Furthermore, in S1, the mixing is carried out by grinding, and the grinding time is 0.5h to 2h.

[0015] Furthermore, in S2, the calcination temperature is 700°C to 1000°C, and the calcination time is 1 hour to 3 hours.

[0016] Furthermore, in S3, the pickling method is: adding the second mixture to a nitric acid solution with an HNO3 concentration of 0.1 mol / L to 1 mol / L, and keeping it warm at 60°C to 80°C for 2h to 10h.

[0017] Furthermore, in S3, the cleaning method is: centrifugal treatment with water and ethanol solution respectively.

[0018] Furthermore, in S2, the inert gas is at least one of nitrogen, helium, and argon.

[0019] Furthermore, in S2, the reducing gas is at least one of hydrogen and ammonia.

[0020] Furthermore, based on the volume fraction of the mixed gas being 100%, the volume fraction of the reducing gas is 3% to 10%.

[0021] Furthermore, the platinum precursor is at least one of platinum acetylacetonate and chloroplatinic acid hexahydrate.

[0022] Furthermore, the transition metal precursor is at least one of manganese acetylacetonate and cobalt acetylacetonate.

[0023] Furthermore, the non-metal source is at least one of sodium phosphate, sodium sulfate, and phthalocyanine.

[0024] Furthermore, the specific surface area of ​​the carbon powder is 800m 2 / g~1400m 2 / g.

[0025] According to a third aspect of the present invention, there is provided a use of the platinum-based fuel cell catalyst of the first aspect of the present invention or the platinum-based fuel cell catalyst prepared by the preparation method of the second aspect of the present invention in preparing a fuel cell membrane electrode.

[0026] By applying the technical solution of the present invention and designing the structure of the platinum-based fuel cell catalyst, the active particles can be stably anchored on the carrier, the probability of active particles falling off can be reduced, and the durability of the platinum-based fuel cell catalyst can be improved. In addition, it also helps to improve the catalytic activity of the platinum-based fuel cell catalyst and improve its overall electrochemical performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a transmission electron microscope image of the platinum-based fuel cell catalyst in Example 1;

[0028] Figure 2 This is a high-angle annular dark-field scanning transmission electron microscopy image of the platinum-based fuel cell catalyst corrected for spherical aberration in Example 1;

[0029] Figure 3 Statistical diagram of particle size of platinum-based fuel cell catalyst in Example 1;

[0030] Figure 4 is the XRD pattern of the platinum-based fuel cell catalyst in Example 1;

[0031] Figure 5 The electrochemical activity bar graph and cyclic voltammetry curve of the platinum-based fuel cell catalyst in Example 1 are shown;

[0032] Figure 6 This is a hydrogen-oxygen polarization curve of the fuel cell membrane electrode in Application Example 1;

[0033] Figure 7 is a hydrogen-air polarization curve of the fuel cell membrane electrode in Application Example 1;

[0034] Figure 8 This is a graph showing the long-term durability of the fuel cell membrane electrode in Application Example 1 at high current density. DETAILED DESCRIPTION

[0035] To make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer are used. Where the manufacturer of the reagents or instruments is not specified, all are conventional products that can be purchased commercially.

[0036] As described in the background of the present invention, the prior art suffers from poor stability of platinum-based fuel cell catalysts, resulting in poor fuel cell performance and short lifespan. To address the above technical issues, in a typical embodiment of the present invention, a platinum-based fuel cell catalyst is provided, comprising a carrier and active particles supported on the carrier, the active particles comprising a core layer and a shell layer located on the surface of the core layer, the core layer comprising a platinum-based intermetallic compound Pt3M, the shell comprising metallic platinum, and at least a portion of the shell layer being coated with a non-metal; wherein M is a transition metal, the non-metal is at least one of N, P, and S, and the carrier is a carbon material; based on 100% by mass of the carrier, the mass fraction of the platinum element in the platinum-based fuel cell catalyst is 10% to 60%; and the average particle size of the active particles is 1 nm to 5 nm.

[0037] The present invention designs the structure of a platinum-based fuel cell catalyst. Using a platinum-based intermetallic compound (Pt3M) as the core layer, the platinum-based fuel cell catalyst exhibits high electrocatalytic activity and a relatively stable structure, thereby improving its stability. Using platinum metal as the shell layer, the platinum metal forms a good bond with the core layer's platinum-based intermetallic compound (Pt3M). Furthermore, the platinum metal has a strong ability to adsorb nonmetallic materials, allowing at least a portion of its surface to be covered by nonmetallic materials. The strong bonding between the nonmetallic material and the carrier carbon material anchors the active particles to the carrier, significantly improving the durability of the platinum-based fuel cell catalyst. Furthermore, controlling the platinum content and the average particle size of the active particles can further improve the stability of the platinum-based fuel cell catalyst and contribute to improving its catalytic activity.

[0038] In some embodiments, in the platinum-based fuel cell catalyst, the molar ratio of platinum element to transition metal element is 1:1 to 9:1, and more preferably 1.2:1 to 9:1; the molar ratio of platinum element to non-metallic element is 3:1 to 9:1; and the non-metallic element is at least one of N, P, and S.

[0039] By controlling the molar ratio of different elements and the types of non-metallic elements, the active particles on the carrier are more stable, less likely to fall off, and less likely to dissolve, and the durability of the platinum-based fuel cell catalyst can be further improved.

[0040] In some embodiments, the transition metal includes at least one of Mn and Co. In the present invention, the structure of the intermetallic compound Pt3M formed by metal platinum, Mn and Co is more stable.

[0041] In some embodiments, based on 100% by mass of the carrier, the mass fraction of the platinum element in the platinum-based fuel cell catalyst is 20% to 40%.

[0042] Controlling the mass fraction of platinum helps to improve both the catalytic activity and stability of platinum-based fuel cell catalysts, thereby enhancing the overall performance of fuel cell catalysts.

[0043] In some embodiments, the electrochemically active area of ​​the platinum-based fuel cell catalyst is 60 m 2 / g Pt ~90m 2 / g Pt .

[0044] In the description of the present invention, the “electrochemically active area” is obtained by normalizing Pt with Pt as the active site.

[0045] Controlling the specific surface area of ​​platinum-based fuel cell catalysts can enable them to have both good catalytic activity and durability.

[0046] In some embodiments, the support is a flaky carbon material.

[0047] In another typical embodiment of the present invention, a method for preparing the platinum-based fuel cell catalyst in the above embodiment is also provided, comprising the following steps:

[0048] S1, mixing a platinum precursor, a transition metal precursor, a non-metallic source, and carbon powder to obtain a first mixture;

[0049] S2, calcining the first mixture in a mixture of an inert gas and a reducing gas to obtain a second mixture;

[0050] S3, acid-washing, cleaning, and drying the second mixture to obtain a platinum-based fuel cell catalyst;

[0051] Wherein, the transition metal precursor is acetylacetonate of transition metal.

[0052] The present invention adopts a solid-phase calcination method to prepare a platinum-based fuel cell catalyst, which has low production cost and high efficiency. In addition, by selecting the type of transition metal precursor, a platinum-based fuel cell catalyst with fine active particle size and good uniformity can be prepared, which is beneficial to improving its stability.

[0053] In one embodiment of the present invention, in S1, mixing is performed by grinding, and the grinding time is 0.5 h to 2 h.

[0054] Controlling the mixing method and mixing conditions is beneficial to uniformly mixing the raw materials and obtaining a platinum-based fuel cell catalyst with uniform composition.

[0055] In one embodiment of the present invention, in S2, the calcination temperature is 700°C to 1000°C, and the calcination time is 1 hour to 3 hours.

[0056] Calcination under the above conditions can produce a platinum-based fuel cell catalyst with a complete structure and fine and uniformly distributed active particles.

[0057] In one embodiment of the present invention, in S3, the pickling method is: adding the second mixture to a nitric acid solution with an HNO3 concentration of 0.1 mol / L to 1 mol / L, and keeping it at 60°C to 80°C for 2h to 10h.

[0058] By controlling the pickling conditions, incompletely alloyed metals can be removed and the catalyst surface can be cleaned.

[0059] In one embodiment of the present invention, in S3, the cleaning method is: centrifugation with water and ethanol solution respectively.

[0060] In one embodiment of the present invention, in S2, the inert gas is at least one of nitrogen, helium, and argon.

[0061] In one embodiment of the present invention, in S2, the reducing gas is at least one of hydrogen and ammonia.

[0062] In one embodiment of the present invention, based on the volume fraction of the mixed gas being 100%, the volume fraction of the reducing gas is 3% to 10%.

[0063] The volume fraction of the reducing gas is controlled on the one hand to reduce the metal ions, and on the other hand for safety considerations.

[0064] In one embodiment of the present invention, the platinum precursor is at least one of platinum acetylacetonate and chloroplatinic acid hexahydrate.

[0065] In one embodiment of the present invention, the transition metal precursor is at least one of manganese acetylacetonate and cobalt acetylacetonate.

[0066] The active particles made from the above two transition metal precursors have strong structural stability, which is beneficial to improving the durability of platinum-based fuel cell catalysts.

[0067] In one embodiment of the present invention, the non-metal source is at least one of sodium phosphate, sodium sulfate, and phthalocyanine.

[0068] The selection of the above-mentioned non-metallic source can form a non-metallic monoatomic layer on the surface of the platinum shell layer, which has a good effect on anchoring the active particles on the carrier.

[0069] In one embodiment of the present invention, the specific surface area of ​​the carbon powder is 800 m 2 / g~1400m 2 / g.

[0070] Controlling the specific surface area of ​​carbon powder can produce platinum-based fuel cell catalysts with better stability and reduce the probability of active particles falling off the carrier.

[0071] In a typical embodiment of the present invention, there is also provided a use of the platinum-based fuel cell catalyst in the above embodiment of the present invention or the platinum-based fuel cell catalyst prepared by the preparation method in the above embodiment in preparing a fuel cell membrane electrode.

[0072] In one embodiment of the present invention, a method for preparing a membrane electrode is provided, comprising: adding a platinum-based fuel cell catalyst to a mixed solution of water and an alcohol solvent, mixing well, and then adding a Nafion solution to obtain a catalyst ink; spraying the catalyst ink onto a proton exchange membrane, and then assembling it with a gas diffusion layer to obtain a fuel cell membrane electrode.

[0073] In one embodiment of the present invention, the mass ratio of the platinum-based fuel cell catalyst to the mixed solution of water and alcohol solvent is 1:20 to 1:5.

[0074] In one embodiment of the present invention, the volume ratio of water to alcohol solvent is 1:10 to 1:1.

[0075] In one embodiment of the present invention, when the mass fraction of Nafion in the Nafion solution is 5%, the mass volume ratio of the platinum-based fuel cell catalyst to the Nafion solution is 1:12 to 1:3 mg / μL.

[0076] In one embodiment of the present invention, the alcohol solvent is at least one of isopropanol, n-propanol, and ethanol.

[0077] The present application is further described in detail below with reference to specific embodiments. These embodiments should not be construed as limiting the scope of protection claimed in this application.

[0078]

Platinum-based fuel cell catalysts

[0079] Example 1

[0080] An embodiment of the platinum-based fuel cell catalyst of the present invention includes the following steps:

[0081] S1, 1g of platinum acetylacetonate, 800mg of manganese acetylacetonate, 200mg of sodium phosphate and 2g of carbon powder (BET specific surface area of ​​800m 2 / g) was added to a mortar and ground in the mortar for 1 h to obtain a first mixture;

[0082] S2, calcining the first mixture in a mixture of ammonia and argon with an ammonia volume fraction of 5% at a temperature of 800° C. for 2 hours, and then naturally cooling to room temperature to obtain a second mixture;

[0083] S3, adding the second mixture to a nitric acid solution with an HNO3 concentration of 0.5 mol / L, keeping the mixture at 60°C for 5 hours, then centrifuging it three times with water and ethanol respectively, and finally drying it at 50°C for 6 hours to obtain a platinum-based fuel cell catalyst.

[0084] Example 2

[0085] An embodiment of the platinum-based fuel cell catalyst of the present invention includes the following steps:

[0086] S1, 1.5g of platinum acetylacetonate, 1.2g of manganese acetylacetonate, 300mg of sodium phosphate and 2g of carbon powder (BET specific surface area of ​​800m 2 / g) was added into a mortar and ground in the mortar for 1 h to obtain a first mixture;

[0087] S2, calcining the first mixture in a mixture of ammonia and argon with an ammonia volume fraction of 10% at a temperature of 700° C. for 3 hours, and then naturally cooling to room temperature to obtain a second mixture;

[0088] S3, adding the second mixture to a nitric acid solution with an HNO3 concentration of 0.5 mol / L, keeping the mixture at 80°C for 2 hours, then centrifuging it three times with water and ethanol respectively, and finally drying it at 50°C for 6 hours to obtain a platinum-based fuel cell catalyst.

[0089] Example 3

[0090] An embodiment of the platinum-based fuel cell catalyst of the present invention includes the following steps:

[0091] S1, 2g of platinum acetylacetonate, 1.6g of manganese acetylacetonate, 300mg of sodium phosphate and 2g of carbon powder (BET specific surface area of ​​800m 2 / g) was added into a mortar and ground in the mortar for 1 h to obtain a first mixture;

[0092] S2, calcining the first mixture in a mixture of ammonia and argon with an ammonia volume fraction of 3% at a temperature of 900° C. for 1 hour, and then naturally cooling to room temperature to obtain a second mixture;

[0093] S3, adding the second mixture to a nitric acid solution with an HNO3 concentration of 0.1 mol / L, keeping the mixture at 80°C for 10 hours, then centrifuging it three times with water and ethanol respectively, and finally drying it at 50°C for 6 hours to obtain a platinum-based fuel cell catalyst.

[0094] Example 4

[0095] An embodiment of the platinum-based fuel cell catalyst of the present invention includes the following steps:

[0096] S1, 0.5g of platinum acetylacetonate, 400mg of manganese acetylacetonate, 100mg of sodium phosphate and 2g of carbon powder (BET specific surface area of ​​800m 2 / g) was added into a mortar and ground in the mortar for 1 h to obtain a first mixture;

[0097] S2, calcining the first mixture in a mixture of ammonia and argon with an ammonia volume fraction of 5% at a temperature of 800° C. for 2 hours, and then naturally cooling to room temperature to obtain a second mixture;

[0098] S3, adding the second mixture to a nitric acid solution with an HNO3 concentration of 0.5 mol / L, keeping the mixture at 60°C for 5 hours, then centrifuging it three times with water and ethanol respectively, and finally drying it at 50°C for 6 hours to obtain a platinum-based fuel cell catalyst.

[0099] Example 5

[0100] An embodiment of the platinum-based fuel cell catalyst of the present invention includes the following steps:

[0101] S1, 3g of platinum acetylacetonate, 2.4g of manganese acetylacetonate, 0.6mg of sodium phosphate and 2g of carbon powder (BET specific surface area of ​​800m 2 / g) was added into a mortar and ground in the mortar for 1 h to obtain a first mixture;

[0102] S2, calcining the first mixture in a mixture of ammonia and argon with an ammonia volume fraction of 5% at a temperature of 800° C. for 2 hours, and then naturally cooling to room temperature to obtain a second mixture;

[0103] S3, adding the second mixture to a nitric acid solution with an HNO3 concentration of 0.5 mol / L, keeping the mixture at 60°C for 5 hours, then centrifuging it three times with water and ethanol respectively, and finally drying it at 50°C for 6 hours to obtain a platinum-based fuel cell catalyst.

[0104] Example 6

[0105] An embodiment of the platinum-based fuel cell catalyst of the present invention includes the following steps:

[0106] S1, 1g of platinum acetylacetonate, 300mg of manganese acetylacetonate, 80mg of sodium phosphate and 2g of carbon powder (BET specific surface area of ​​800m 2 / g) was added into a mortar and ground in the mortar for 1 h to obtain a first mixture;

[0107] S2, calcining the first mixture in a mixture of ammonia and argon with an ammonia volume fraction of 5% at a temperature of 800° C. for 2 hours, and then naturally cooling to room temperature to obtain a second mixture;

[0108] S3, adding the second mixture to a nitric acid solution with an HNO3 concentration of 0.5 mol / L, keeping the mixture at 60°C for 5 hours, then centrifuging it three times with water and ethanol respectively, and finally drying it at 50°C for 6 hours to obtain a platinum-based fuel cell catalyst.

[0109] Example 7

[0110] An embodiment of the platinum-based fuel cell catalyst of the present invention includes the following steps:

[0111] S1, 1g of platinum acetylacetonate, 1.2g of manganese acetylacetonate, 300mg of sodium phosphate and 2g of carbon powder (BET specific surface area of ​​800m 2 / g) was added into a mortar and ground in the mortar for 1 h to obtain a first mixture;

[0112] S2, calcining the first mixture in a mixture of ammonia and argon with an ammonia volume fraction of 5% at a temperature of 800° C. for 2 hours, and then naturally cooling to room temperature to obtain a second mixture;

[0113] S3, adding the second mixture to a nitric acid solution with an HNO3 concentration of 0.5 mol / L, keeping the mixture at 60°C for 5 hours, then centrifuging it three times with water and ethanol respectively, and finally drying it at 50°C for 6 hours to obtain a platinum-based fuel cell catalyst.

[0114] Example 8

[0115] An embodiment of the platinum-based fuel cell catalyst of the present invention includes the following steps:

[0116] S1, 1g of platinum acetylacetonate, 2.4g of manganese acetylacetonate, 600mg of sodium phosphate and 2g of carbon powder (BET specific surface area of ​​800m 2 / g) was added into a mortar and ground in the mortar for 1 h to obtain a first mixture;

[0117] S2, calcining the first mixture in a mixture of ammonia and argon with an ammonia volume fraction of 5% at a temperature of 800° C. for 2 hours, and then naturally cooling to room temperature to obtain a second mixture;

[0118] S3, adding the second mixture to a nitric acid solution with an HNO3 concentration of 0.5 mol / L, keeping the mixture at 60°C for 5 hours, then centrifuging it three times with water and ethanol respectively, and finally drying it at 50°C for 6 hours to obtain a platinum-based fuel cell catalyst.

[0119] Example 9

[0120] An embodiment of the platinum-based fuel cell catalyst of the present invention includes the following steps:

[0121] S1, 1g of platinum acetylacetonate, 100mg of manganese acetylacetonate, 25mg of sodium phosphate and 2g of carbon powder (BET specific surface area of ​​800m 2 / g) was added into a mortar and ground in the mortar for 1 h to obtain a first mixture;

[0122] S2, calcining the first mixture in a mixture of ammonia and argon with an ammonia volume fraction of 5% at a temperature of 800° C. for 2 hours, and then naturally cooling to room temperature to obtain a second mixture;

[0123] S3, adding the second mixture to a nitric acid solution with an HNO3 concentration of 0.5 mol / L, keeping the mixture at 60°C for 5 hours, then centrifuging it three times with water and ethanol respectively, and finally drying it at 50°C for 6 hours to obtain a platinum-based fuel cell catalyst.

[0124] Example 10

[0125] An embodiment of the platinum-based fuel cell catalyst of the present invention includes the following steps:

[0126] S1, 1g of platinum acetylacetonate, 800mg of cobalt acetylacetonate, 200mg of sodium sulfate and 2g of carbon powder (BET specific surface area of ​​800m 2 / g) was added into a mortar and ground in the mortar for 1 h to obtain a first mixture;

[0127] S2, calcining the first mixture in a mixture of ammonia and argon with an ammonia volume fraction of 5% at a temperature of 800° C. for 2 hours, and then naturally cooling to room temperature to obtain a second mixture;

[0128] S3, adding the second mixture to a nitric acid solution with an HNO3 concentration of 0.5 mol / L, keeping the mixture at 60°C for 5 hours, then centrifuging it three times with water and ethanol respectively, and finally drying it at 50°C for 6 hours to obtain a platinum-based fuel cell catalyst.

[0129] Example 11

[0130] An embodiment of the platinum-based fuel cell catalyst of the present invention includes the following steps:

[0131] S1, 1.3g chloroplatinic acid hexahydrate, 800mg cobalt acetylacetonate, 600mg phthalocyanine and 2g carbon powder (BET specific surface area of ​​800m 2 / g) was added into a mortar and ground in the mortar for 1 h to obtain a first mixture;

[0132] S2, calcining the first mixture in a mixture of ammonia and argon with an ammonia volume fraction of 5% at a temperature of 800° C. for 2 hours, and then naturally cooling to room temperature to obtain a second mixture;

[0133] S3, adding the second mixture to a nitric acid solution with an HNO3 concentration of 0.5 mol / L, keeping the mixture at 60°C for 5 hours, then centrifuging it three times with water and ethanol respectively, and finally drying it at 50°C for 6 hours to obtain a platinum-based fuel cell catalyst.

[0134]

Fuel Cell Membrane Electrode

[0135] Application Examples 1 to 11

[0136] Application Examples 1 to 11 are fuel cell membrane electrodes made using the platinum-based fuel cell catalysts in Examples 1 to 11, and the preparation methods are as follows:

[0137] 20 mg of fuel cell catalyst was added to a mixture of 0.5 mL of water and 5 mL of isopropanol, and after ultrasonic homogenization, it was added to 200 μL of Nafion solution with a mass fraction of 5% to obtain catalyst ink. The catalyst ink was then evenly sprayed onto a proton exchange membrane (Gore, ~12 μm) using a spray gun, and then assembled with a gas diffusion layer (Toray, Japan, TGP-H-060) to form a fuel cell membrane electrode.

[0138]

Performance test

[0139] 1. Platinum-based fuel cell catalysts

[0140] 1) Element content: The atomic ratio and mass ratio of various element contents were analyzed using a scanning electron microscope-energy dispersive spectrometer.

[0141] 2) Average particle size of active particles: Based on transmission electron microscopy images, the particle size was measured and statistically analyzed using nanometer measurement software.

[0142] 3) Morphology: The morphology was observed using a transmission electron microscope and a spherical aberration-corrected high-angle annular dark-field scanning transmission electron microscope.

[0143] 4) Structure: XRD pattern was tested using X-ray diffractometer.

[0144] 5) Electrochemically active area (ECSA) of the catalyst: The catalyst was coated onto a rotating disk electrode to prepare the working electrode to be used. A saturated calomel electrode was used as the reference electrode and a graphite rod was used as the counter electrode. The catalyst was first activated by cyclic voltammetry in a nitrogen-saturated HClO solution with a concentration of 0.1 mol / L at a scan rate of 50 mV·s. -1 The scanning potential range was from -0.25 V to 0.96 V, and the ECSA was calculated using the hydrogen region of the electrochemical cyclic voltammetry curve.

[0145] 6) Mass activity: ORR performance was tested by linear sweep voltammetry in an O2-saturated HClO4 solution with a concentration of 0.1 mol / L. The scan rate and rotation speed were maintained at 10 mV·s, respectively. -1 and 1600 rpm, and the current at 0.9 V (vs. RHE) was taken, and the mass activity was calculated using the KL equation.

[0146] 2. Fuel cell membrane electrode

[0147] The fuel cell membrane electrode performance was tested using fuel cell testing equipment. During the test, the cell temperature was always maintained at 80°C and the back pressure was set to 150kPa. abs Before starting data collection, the fuel cell membrane electrode was maintained at a cell voltage of 0.85V, 0.6V, 0.5V and 0.4V for 5 minutes each, and repeated 8-10 cycles until the current density stabilized at a constant value. For the H2 / O2 single cell test, the H2 / O2 flow rate was 500 / 500sccm. For the H2 / air single cell test, the H2 / air flow rate was 500 / 2000sccm, and the steady-state polarization curve was also obtained. The operating life was tested using the timed constant current method at 1.5A·cm -2 The anode and cathode were supplied with H2 and O2 at a flow rate of 200 sccm, respectively.

[0148] Table 1 and Table 2 are the performance test results of platinum-based fuel cell catalysts and fuel cell membrane electrodes, respectively.

[0149] Table 1

[0150]

[0151] As can be seen from Table 1, when the platinum loading ranges from 16.6% to 55.6%, the average particle size and ECSA of the active particles are maintained in a good state; when the molar ratio of platinum element to transition metal element is 1:1 to 9:1, the ECSA and mass activity of the catalyst are relatively high; in addition, when the molar ratio of platinum element to non-metallic element is 3:1 to 9:1, the average particle size of the active particles in the catalyst, as well as the ECSA and mass activity of the catalyst are maintained in a relatively good state; in addition, as can be seen from Table 1, replacing the transition metal manganese with cobalt and sodium phosphate with sodium sulfate or phthalocyanine can maintain a good structural state.

[0152] Figure 1 This is a transmission electron microscope image of the platinum-based fuel cell catalyst in Example 1; as can be seen from the image, in the platinum-based fuel cell catalyst prepared by the present invention, the active particles are evenly distributed on the thin film carbon material. Figure 2 This is a high-angle annular dark-field scanning transmission electron microscopy image of the spherical aberration corrected platinum-based fuel cell catalyst in Example 1. As can be seen from the image, in the platinum-based fuel cell catalyst prepared by the present invention, the active particles include a core layer and a shell layer located on the surface of the core layer. The material of the core layer includes a platinum-based intermetallic compound Pt3M, and the material of the shell layer includes metallic platinum. At least part of the surface of the shell layer is wrapped by a non-metal, which is conducive to forming a stable structure with the carrier. Figure 3 Statistical diagram of the particle size of the platinum-based fuel cell catalyst in Example 1; it can be seen from the figure that the particle size distribution of the platinum-based fuel cell catalyst in Example 1 is relatively narrow. Figure 4 3 is the XRD pattern of the platinum-based fuel cell catalyst in Example 1. Compared with the standard card, it can be seen that the main component of the platinum-based fuel cell catalyst prepared in the present invention is Pt3Mn intermetallic compound. Figure 5 The electrochemical activity bar graph and cyclic voltammogram of the platinum-based fuel cell catalyst in Example 1 are shown. As can be seen from the figure, after 30,000 cycles, the cyclic voltammogram has almost no change, further indicating that the platinum-based fuel cell catalyst prepared by the present invention has good stability.

[0153] Table 2

[0154] project <![CDATA[Hydrogen-air peak power density (W / cm 2 )]]> <![CDATA[Hydrogen-oxygen peak power density (W / cm 2 )]]> Operating life (h) Example 1 1.42 2.68 500 Example 2 1.53 2.81 NA Example 3 1.72 2.93 NA Example 4 1.27 2.32 NA Example 5 1.89 3.13 NA Example 6 1.12 2.08 NA Example 7 1.25 2.16 NA Example 8 0.89 1.84 NA Example 9 0.95 1.91 NA Example 10 1.36 2.53 NA Example 11 1.32 2.45 NA

[0155] As can be seen from Table 2, the power density of the fuel cell membrane electrode prepared using the platinum-based fuel cell catalyst of the present invention is maintained at a high level. In addition, when the molar ratio of platinum element and non-metallic element in the platinum-based fuel cell catalyst is 3:1 to 9:1, the fuel cell membrane electrode prepared using the platinum-based fuel cell catalyst has high ECSA, high mass activity and high power density.

[0156] Figure 6 The hydrogen-oxygen polarization curve of the fuel cell membrane electrode in Example 1 is shown in the figure. As can be seen from the figure, the hydrogen-oxygen peak power density of the fuel cell membrane electrode reaches 2.68W / cm 2 ; Figure 7 The hydrogen-air polarization curve of the fuel cell membrane electrode in Example 1 is shown in the figure. As can be seen from the figure, the hydrogen-air peak power density of the fuel cell membrane electrode reaches 1.42W / cm 2 ; Figure 8 The long-term durability diagram of the fuel cell membrane electrode in application example 1 at high current density is shown in the figure. -2 At high current density, its voltage can be maintained for up to 500h without obvious attenuation, and has good cycle stability.

[0157] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A platinum-based fuel cell catalyst, characterized in that: The platinum-based fuel cell catalyst includes a carrier and active particles loaded on the carrier, the active particles include a core layer and a shell layer located on the surface of the core layer, the material of the core layer includes a platinum-based intermetallic compound Pt3M, the material of the shell layer includes metallic platinum, and at least a portion of the surface of the shell layer is wrapped by a non-metal; the M is a transition metal, the non-metal is at least one of N, P, and S, and the carrier is a carbon material; based on the mass fraction of the carrier being 100%, the mass fraction of the platinum element in the platinum-based fuel cell catalyst is 10% to 60%; the average particle size of the active particles is 1nm to 5nm.

2. The platinum-based fuel cell catalyst according to claim 1, characterized in that In the platinum-based fuel cell catalyst, the molar ratio of platinum element to transition metal element is 1:1 to 9:1, and the molar ratio of platinum element to non-metallic element is 3:1 to 9:1; the non-metallic element is at least one of N, P, and S.

3. The platinum-based fuel cell catalyst according to claim 2, characterized in that The transition metal includes at least one of Mn and Co.

4. The platinum-based fuel cell catalyst according to claim 1, characterized in that Based on the mass fraction of the carrier being 100%, the mass fraction of the platinum element in the platinum-based fuel cell catalyst is 20% to 40%; and / or the electrochemical active area of ​​the platinum-based fuel cell catalyst is 60m 2 / g Pt ~90m 2 / g Pt .

5. A method for preparing a platinum-based fuel cell catalyst according to any one of claims 1 to 4, characterized in that: The steps include: S1, mixing a platinum precursor, a transition metal precursor, a non-metallic source, and carbon powder to obtain a first mixture; S2, calcining the first mixture in a mixture of an inert gas and a reducing gas to obtain a second mixture; S3, acid-washing, cleaning, and drying the second mixture to obtain the platinum-based fuel cell catalyst; The transition metal precursor is acetylacetonate of a transition metal.

6. The preparation method according to claim 5, characterized in that In S1, the mixing is carried out by grinding, and the grinding time is 0.5h to 2h; and / or, in S2, the calcination temperature is 700℃ to 1000℃, and the time is 1h to 3h; and / or, in S3, the pickling method is: adding the second mixture to a nitric acid solution with an HNO3 concentration of 0.1mol / L to 1mol / L, and keeping it warm at 60℃ to 80℃ for 2h to 10h; the cleaning method is: centrifuging with water and ethanol solution respectively.

7. The preparation method according to claim 5, characterized in that In S2, the inert gas is at least one of nitrogen, helium, and argon, and the reducing gas is at least one of hydrogen and ammonia; and / or, based on the volume fraction of the mixed gas being 100%, the volume fraction of the reducing gas is 3% to 10%.

8. The preparation method according to claim 5, characterized in that The platinum precursor is at least one of platinum acetylacetonate and chloroplatinic acid hexahydrate; and / or the transition metal precursor is at least one of manganese acetylacetonate and cobalt acetylacetonate; and / or the non-metal source is at least one of sodium phosphate, sodium sulfate, and phthalocyanine.

9. The preparation method according to claim 5, characterized in that The specific surface area of ​​the carbon powder is 800m 2 / g~1400m 2 / g.

10. Use of the platinum-based fuel cell catalyst according to any one of claims 1 to 4 or the platinum-based fuel cell catalyst prepared by the preparation method according to any one of claims 5 to 9 in the preparation of a fuel cell membrane electrode.

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