A b-doped graphene porous membrane supported platinum nanocrystal electrode material

Abstract

The application discloses a B-doped graphene porous membrane loaded platinum nanocrystal electrode material, which is used for constructing a fuel cell electrode with ultra-low platinum consumption. The graphene is deposited on an aluminum foil by an arc discharge method, has abundant porosity and high graphitization, and provides an efficient mass transfer channel and excellent corrosion resistance; on the basis, platinum nanocrystals are deposited to serve as a catalyst layer of the fuel cell. The method is easy to operate, has a short preparation period, and has relatively low platinum cost, so that the production cost of the product is reduced; meanwhile, the method is used for performance test in the ultra-low platinum fuel cell, and the results show that the power density and the current density are higher than those of a commercial powder-based Pt / C catalyst and a pure graphene membrane electrode prepared in the same way.

Description

Technical Field

[0001] This invention relates to the field of fuel cell technology, specifically to a platinum nanocrystalline electrode material supported on a boron-doped graphene porous membrane. Background Technology

[0002] A proton exchange membrane fuel cell (PEMFC) is an electrochemical energy conversion device that uses hydrogen as fuel, oxygen / air as oxidant, and a proton exchange membrane as a solid electrolyte. It features low operating temperature, fast start-up, and high energy conversion efficiency, making it an ideal power source for new energy vehicles. The membrane electrode assembly (MEA) is the core of the PEMFC reaction, mainly composed of a proton exchange membrane, a catalyst layer, and a gas diffusion layer. Its structural design and fabrication process are key technologies in fuel cell research, determining the battery's performance and practical application. The catalyst layer is the most crucial structural element determining the MEA's performance and is also the most important factor influencing whether the fuel cell can operate with low platinum loading.

[0003] The most common method for preparing membrane electrode assemblies (MEAs) is ultrasonic spraying, in which a catalyst, ion exchange resin solution, and alcohol are mixed in a certain proportion and uniformly sprayed onto a gas diffusion layer. However, this method has the following drawbacks: (1) the catalyst utilization rate is low due to the stacking of catalyst particles in the prepared slurry; (2) the ion exchange resin solution is unevenly distributed on the catalyst, resulting in a significant increase in proton transport resistance; and (3) the alcohol solvent easily causes uneven dispersion of catalyst particles when dispersing the powdered catalyst, thus greatly increasing the electron transport resistance. Therefore, the traditional method for preparing powder-based fuel cell MEAs significantly reduces the performance of fuel cells and requires a high amount of Pt-based noble metal catalyst. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a method for preparing ultra-low platinum fuel cells based on boron-doped graphene porous films. The method primarily employs electrostatic adsorption to deposit arc-exfoliated graphene as a porous film onto aluminum foil. Catalyst particles and ion-exchange resin solutions are then coated onto the graphene porous film using atomic layer deposition and electrostatic spraying, respectively. Finally, the ultra-low platinum fuel cell membrane electrode assembly (MEA) is fabricated using a hot-press transfer method. The graphene porous membrane ultra-low platinum fuel cell prepared by this method exhibits excellent performance.

[0005] To achieve the above objectives, the technical solution provided by the present invention is as follows:

[0006] A boron-doped graphene porous membrane-supported platinum nanocrystal electrode material is disclosed. The graphene is deposited on aluminum foil using an arc discharge method, exhibiting abundant porosity and high graphitization, providing efficient mass transfer channels and excellent corrosion resistance. Platinum nanocrystals are then deposited on this membrane to serve as a catalyst layer for a fuel cell.

[0007] The preparation method of the platinum nanocrystalline electrode material supported by B-doped graphene porous film as described above includes the following steps:

[0008] (1) Cut aluminum foil to a length of 10.0cm and a width of 8.0cm, clean the surface with anhydrous ethanol, and use it as a porous graphene deposition substrate;

[0009] (2) A graphite rod with a purity of 99.99% was used as the raw material for arc exfoliation of graphene, and a hole was drilled on one end of the graphite rod. Then, a boron source was injected into the hole.

[0010] (3) Adhere the porous graphene deposition substrate obtained in step (1) to the top of the arc chamber. Place the graphite rod with boron source injected in step (2) at the anode end of the arc chamber. Take a graphite rod with a purity of 99.99%, sharpen one end, and place it at the cathode end of the arc chamber. After evacuation, introduce argon and hydrogen to make the pressure ≥30kPa. Then perform arc stripping to obtain B-doped graphene porous film (abbreviated as 3D-PBG).

[0011] (4) The B-doped graphene porous film obtained in step (3) is placed in the reaction chamber of atomic layer deposition (ALD). Under ALD conditions, the chamber temperature is raised to 297-300℃, vacuum is drawn, and the temperature of the source bottle with platinum source is raised to the temperature that can reach the saturated vapor pressure of platinum source for deposition cycle. Then, platinum deposition cycle is performed. Platinum particles with different loadings are prepared by controlling the number of cycles to obtain B-doped graphene porous film with deposited platinum nanoparticles.

[0012] (5) Cut the B-doped graphene porous film with deposited platinum nanoparticles obtained in step (4) into 2.2cm × 2.2cm pieces. Spray the B-doped graphene porous film with deposited platinum nanoparticles obtained in step (4) uniformly with an ion exchange resin solution and dry it to obtain the B-doped graphene porous film loaded with platinum nanocrystal electrode material (abbreviated as Pt / 3D-PBG). The platinum loading of the B-doped graphene porous film loaded with platinum nanocrystal electrode material is 20-80 μg / cm³. 2 .

[0013] Preferably, the amount of boron source injected in step (2) is 291.5 mg of boron source injected per 1 square centimeter of hole volume; the diameter of the hole is 0.5 cm and the depth is 2 cm; the boron source in step (2) is one of boric acid, boron carbide, fluoroboric acid or metaboric acid.

[0014] Preferably, the vacuuming in step (3) is to maintain a vacuum level of ≤3.0 Pa; the hydrogen flow rate in step (3) is 300 sccm and the argon flow rate is 188 sccm.

[0015] Preferably, the arc stripping time in step (3) is 30-35s.

[0016] Preferably, the vacuum in the atomic layer deposition (ALD) reaction chamber in step (4) is evacuated to a vacuum level of 7-10 mbar; the platinum source in step (4) is methylcyclopentadienyl-trimethylplatinum; and the temperature at which the saturated vapor pressure of the platinum source can be reached is 75°C.

[0017] Preferably, the platinum deposition cycle in step (4) is as follows: open the source bottle for 300 ms, supply the platinum source, expose for 5 s to allow the platinum source to be adsorbed onto the 3D-PBG, then introduce N2 for 10 s to remove the unadsorbed platinum source, then introduce O2 for 2 s to react with the platinum source, and then immediately purify with N2 for 15 s to remove other substances produced by the reaction, thus completing one platinum deposition cycle.

[0018] Preferably, the ion exchange resin liquid in step (5) is an ion exchange resin solution diluted with an alcohol solvent to a concentration of 2 mg / ml; the spraying loading is 5-30 μg / cm³. 2 The drying time is 30 minutes.

[0019] Preferably, the ion exchange resin solution is one of DuPont Nafion solutions D520, D521, D1020, D1021, or D2020; the ion exchange resin solution is a commercially available specification with a content of 5%-20%; and the spraying loading is 20 μg / cm³. 2 The alcohol solvent is ethanol or isopropanol.

[0020] The above-prepared boron-doped graphene porous membrane-supported platinum nanocrystalline electrode material (Pt / 3D-PBG) is used in the construction of ultra-low platinum content fuel cell electrodes. The Pt / 3D-PBG can serve as both the cathode and anode of the fuel cell; when used as a cathode, the platinum (Pt) loading of the Pt / 3D-PBG is 50-80 μg / cm³. 2 When used as an anode, the platinum (Pt) loading of the Pt / 3D-PBG is 20 μg / cm³. 2 .

[0021] The application described above includes the following operational steps:

[0022] (i) Place the Pt / 3D-PBG, which serves as the cathode and the anode, on both sides of the proton exchange membrane, and finally place it in a hot press. Perform hot pressing transfer at 135°C and 480 kgf for 180 s to transfer the Pt / 3D-PBG onto the proton exchange membrane.

[0023] (ii) Place the gas diffusion layer on both sides of the proton exchange membrane obtained after the transfer in step (i), and hot press it at 135°C and 15 kgf for 10 s to make a proton exchange membrane electrode (MEA), which is an ultra-low platinum fuel cell electrode.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] This invention optimizes the preparation process, allowing 3D-PBG to be exfoliated into sheets under specific pressure. Combined with the characteristics of atomic layer deposition (ALD), this provides more deposition sites for platinum particles, making it easier and allowing boron-doped graphene to be deposited on porous films at smaller sizes, thus improving deposition efficiency and the utilization rate of platinum nanocrystals. The introduction of boron leads to charge transfer between graphene and platinum nanocrystals, changing the d-band center. This interaction between the substrate and the support enhances the catalytic activity of platinum particles, reduces platinum usage, and increases the interaction force between graphene and platinum particles, improving fuel cell stability. Furthermore, the method of this invention is easy to operate, has a short preparation cycle, and relatively low platinum cost, thus reducing the production cost of the product. Performance tests using this method in ultra-low platinum fuel cells showed higher power density and greater current density than commercial powder-based Pt / C catalysts and pure graphene membrane electrodes prepared in the same manner. Attached Figure Description

[0026] Figure 1 The graphite rod used in this invention; wherein, 1-the graphite rod with a hole punched in step (2), 2-the graphite rod with one end in a pointed cone shape; 11 is the hole.

[0027] Figure 2 (a) is a SEM image of the B-doped graphene porous film (3D-PBG) prepared in step (3) of Example 1, with a scale bar of 500 nm. It is a picture of B-doped graphene obtained by SEM testing and observation; (aⅠ) is the EDS image corresponding to (a); (b) is a SEM image of the B-doped graphene porous film (3D-PBG) prepared in step (3) of Example 1, with a scale bar of 1 μm.

[0028] Figure 3 Example 1 describes the preparation of a platinum nanocrystalline electrode material (Pt / 3D-PBG) supported on a boron-doped graphene porous film, and the testing of its IV polarization curve and power density curve; wherein the platinum loading is 80 μg / cm³. 2The Pt / 3D-PBG cathode has a platinum loading of 20 μg / cm³. 2 The anode is 0.

[0029] Figure 4 These are SEM images of B-doped graphene porous films (3D-PBG) prepared under different pressures; where (a) is 3D-PBG prepared at 10 kPa, (b) is 3D-PBG prepared at 20 kPa, (c) is 3D-PBG prepared at 30 kPa (B-doped graphene porous film prepared in step (3) of Example 1), and (d) is 3D-PBG prepared at 40 kPa.

[0030] Figure 5 Raman spectra of benzene-doped porous graphene films (3D-PBG) prepared under different pressures; from top to bottom, they are 40 kPa, 30 kPa, 20 kPa, and 10 kPa.

[0031] Figure 6 Using B-doped graphene porous film-supported platinum nanocrystalline electrode material (Pt / 3D-PBG) prepared under different arc exfoliation times as the cathode, the platinum loading was 20 μg / cm³. 2 The membrane electrode prepared under the anodic conditions was tested on an 850e fuel cell test station, and the resulting polarization curve and power density curve were obtained.

[0032] Figure 7 It is a membrane electrode made of commercial platinum-carbon, with a platinum loading of 200 μg / cm³ at both the anode and cathode. 2 Below are the polarization curves and power density curves obtained from tests conducted on the 850e fuel cell test station.

[0033] Figure 8 (a) is a TEM image of the B-doped graphene porous film (3D-PBG) prepared in step (3) of Example 1, and (b) and (c) are TEM images of the Pt / 3D-PBG prepared in step (5) of Example 1. Detailed Implementation

[0034] The specific embodiments are described in detail below with reference to the accompanying drawings, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments. Unless otherwise specified, the raw materials and reagents used in the embodiments are commercially available.

[0035] The atomic layer deposition system (ALD) and plasma vacuum arc furnace used in the embodiments are commercially available.

[0036] The proton exchange membrane was a commercially available NRE211 model, and the gas diffusion layer was a commercially available H24XC483 model. In this embodiment, the graphite rod was a commercially available graphite rod with a purity of 99.99%. The ion exchange resin solution used in this embodiment was a commercially available ion exchange resin solution with a content of 5%-20% (mass percentage of solute).

[0037] Example 1

[0038] 1.1 A method for preparing a platinum nanocrystalline electrode material supported on a boron-doped graphene porous film as a cathode, comprising the following steps:

[0039] (1) Cut the aluminum foil into a length of 10.0cm and a width of 8.0cm, weigh it to 307.56mg, clean the surface with anhydrous ethanol, and use it as a porous graphene deposition substrate.

[0040] (2) A graphite rod (1 cm in diameter and 1 m in length) is used as the raw material for arc exfoliation of graphene, and a hole 11 with a diameter of 0.5 cm and a depth of 2 cm is drilled inward on one end of the graphite rod (e.g., Figure 1 (As shown), then 291.5 mg of boric acid (boron source) was injected into the drilled hole and compacted;

[0041] (3) Adhere the porous graphene deposition substrate obtained in step (1) to the top of the arc chamber of the plasma vacuum arc furnace, and place the graphite rod with the injected boron source obtained in step (2) at the anode end of the arc chamber of the plasma vacuum arc furnace; take a brand new graphite rod (1 cm in diameter and 10 cm in length), and sharpen one end (e.g. Figure 1 As shown in Figure 2), the graphene was placed at the cathode end of the arc chamber of a plasma vacuum arc furnace. A vacuum of 3.0 Pa was maintained, and then argon and hydrogen were introduced (hydrogen flow rate of 300 sccm and argon flow rate of 188 sccm) to bring the pressure inside the arc chamber to 30 kPa. Arc stripping was then performed for 30 s, yielding a boron-doped graphene porous film (3D-PBG). After stripping, the arc chamber was degassed, the chamber was opened, and the obtained 3D-PBG was removed, weighing 311.54 mg. The prepared 3D-PBG was subjected to scanning electron microscopy, EDS analysis, and Raman spectroscopy. The results are shown in Figure 2. Figure 2 , Figure 4 , Figure 5 As shown, TEM Figure 8 As shown in (a);

[0042] (4) The 3D-PBG obtained in step (3) is placed in the reaction chamber of an atomic layer deposition (ALD) system. Under ALD conditions, the chamber temperature is raised to 300°C, the vacuum is evacuated to 8 mbar, and the temperature of the source bottle containing the platinum source (methylcyclopentadienyl)-trimethylplatinum (MeCpPtMe3, 99%) is raised to 75°C to achieve the saturated vapor pressure of the platinum source. The deposition cycle steps are as follows: the source bottle is opened for 300 ms, the platinum source is supplied, exposed for 5 s to allow the platinum source to be adsorbed onto the 3D-PBG, then N2 is introduced for 10 s to remove the unadsorbed platinum source, then O2 is introduced for 2 s to react with the platinum source for 2 s, and then immediately purified with N2 for 15 s to remove other substances produced by the reaction, thus completing one platinum deposition cycle. 130 ALD platinum deposition cycles are performed to obtain a B-doped graphene porous membrane with deposited platinum nanoparticles, weighing 317.94 mg, with a platinum loading of 80 μg / cm³. 2 ;

[0043] (5) Dilute the DuPont Nafion D520 solution of the ion exchange resin solution to 2 mg / mL with anhydrous ethanol; cut the B-doped graphene porous film deposited with platinum nanoparticles in step (4) into 2.2 cm × 2.2 cm pieces, and then place them in an electrostatic sprayer. Use the diluted ion exchange resin solution to uniformly electrostatically spray the cut B-doped graphene porous film deposited with platinum nanoparticles. The spray loading is 20 μg / cm. 2 Drying at 80℃ for 30 min yields a platinum nanocrystalline electrode material supported on a boron-doped graphene porous film (Pt / 3D-PBG), which serves as the cathode. TEM images of Pt / 3D-PBG are shown below. Figure 8 As shown in (b) and (c).

[0044] 1.2 A method for preparing a platinum nanocrystalline electrode material supported on a boron-doped graphene porous film as an anode, comprising the following steps:

[0045] In step (4), 70 ALD platinum deposition cycles were performed to obtain a B-doped graphene porous film with deposited platinum nanoparticles, weighing 313 mg, with a platinum loading of 20 μg / cm³. 2 ;

[0046] The remaining operations are the same as steps (1)-(5) of Example 1, “1.1. A method for preparing a platinum nanocrystal electrode material supported on a B-doped graphene porous film as a cathode”, to obtain Pt / 3D-PBG as an anode.

[0047] Example 2

[0048] A method for preparing a platinum nanocrystalline electrode material supported on a boron-doped graphene porous film, comprising the following steps:

[0049] (1) Cut the aluminum foil into a length of 10.0cm and a width of 8.0cm, weigh it to 307.56mg, clean the surface with anhydrous ethanol, and use it as a porous graphene deposition substrate.

[0050] (2) A graphite rod (1 cm in diameter and 1 m in length) is used as the raw material for arc exfoliation of graphene, and a hole 11 with a diameter of 0.5 cm and a depth of 2 cm is drilled inward on one end of the graphite rod (e.g., Figure 1 (As shown), then 291.5 mg of boric acid (boron source) was injected into the drilled hole and compacted;

[0051] (3) Adhere the porous graphene deposition substrate obtained in step (1) to the top of the arc chamber of the plasma vacuum arc furnace, and place the graphite rod with the injected boron source obtained in step (2) at the anode end of the arc chamber of the plasma vacuum arc furnace; take a brand new graphite rod (1 cm in diameter and 10 cm in length), and sharpen one end (e.g. Figure 1 As shown in Figure 2), it is then placed at the cathode end of the arc chamber of the plasma vacuum arc furnace; a vacuum is drawn to maintain a vacuum degree of 2.5 Pa, and then argon and hydrogen are introduced (the flow rate of hydrogen is 300 sccm and the flow rate of argon is 188 sccm) to make the pressure in the arc chamber 32 kPa, and then arc stripping is performed for 32 s, which yields B-doped graphene porous film (abbreviated as 3D-PBG). After stripping, the vacuum in the arc chamber is broken, the chamber is opened, and the obtained 3D-PBG is taken out and weighed 312.54 mg.

[0052] (4) The 3D-PBG obtained in step (3) is placed in the reaction chamber of an atomic layer deposition (ALD) system. Under ALD conditions, the chamber temperature is raised to 300°C, the vacuum is evacuated to 8 mbar, and the temperature of the source bottle containing the platinum source (methylcyclopentadienyl)-trimethylplatinum (MeCpPtMe3, 99%) is raised to 75°C to achieve the saturated vapor pressure of the platinum source. The deposition cycle steps are as follows: the source bottle is opened for 300 ms, the platinum source is supplied, exposed for 5 s to allow the platinum source to be adsorbed onto the 3D-PBG, then N2 is introduced for 10 s to remove the unadsorbed platinum source, then O2 is introduced for 2 s to react with the platinum source for 2 s, and then immediately purified with N2 for 15 s to remove other substances produced by the reaction, thus completing one platinum deposition cycle. 100 ALD platinum deposition cycles are performed to obtain a B-doped graphene porous membrane with deposited platinum nanoparticles, weighing 316.54 mg, with a platinum loading of 50 μg / cm³. 2 ;

[0053] (5) Dilute the DuPont Nafion D520 solution in the ion exchange resin solution to 2 mg / ml with anhydrous isopropanol; cut the B-doped graphene porous film deposited with platinum nanoparticles in step (4) into 2.2 cm × 2.2 cm pieces, and then place them in an electrostatic sprayer. Use the diluted ion exchange resin solution to uniformly electrostatically spray the cut B-doped graphene porous film deposited with platinum nanoparticles. The spray loading is 10 μg / cm. 2 Drying at 80℃ for 30 minutes yields a B-doped graphene porous film-supported platinum nanocrystalline electrode material (Pt / 3D-PBG), which is used as a cathode.

[0054] Example 3

[0055] A method for preparing a platinum nanocrystalline electrode material supported on a boron-doped graphene porous film, comprising the following steps:

[0056] (1) Cut the aluminum foil into a length of 10.0cm and a width of 8.0cm, weigh it to 307.56mg, clean the surface with anhydrous ethanol, and use it as a porous graphene deposition substrate.

[0057] (2) A graphite rod (1 cm in diameter and 1 m in length) is used as the raw material for arc exfoliation of graphene, and a hole 1 with a diameter of 0.5 cm and a depth of 2 cm is drilled inward on one end of the graphite rod (e.g., Figure 1 (As shown), then 291.5 mg of boric acid (boron source) was injected into the drilled hole and compacted;

[0058] (3) Adhere the porous graphene deposition substrate obtained in step (1) to the top of the arc chamber of the plasma vacuum arc furnace, and place the graphite rod with the injected boron source obtained in step (2) at the anode end of the arc chamber of the plasma vacuum arc furnace; take a brand new graphite rod (1 cm in diameter and 10 cm in length), and sharpen one end (e.g. Figure 1 As shown in Figure 2), it is then placed at the cathode end of the arc chamber of the plasma vacuum arc furnace; a vacuum is drawn to maintain a vacuum degree of 2.0 Pa, and then argon and hydrogen are introduced (the flow rate of hydrogen is 300 sccm and the flow rate of argon is 188 sccm) to make the pressure in the arc chamber 35 kPa, and then arc stripping is performed for 35 s, which yields B-doped graphene porous film (abbreviated as 3D-PBG). After stripping, the vacuum in the arc chamber is broken, the chamber is opened, and the obtained 3D-PBG is taken out and weighed 311.54 mg.

[0059] (4) The 3D-PBG obtained in step (3) is placed in the reaction chamber of an atomic layer deposition (ALD) system. Under ALD conditions, the chamber temperature is raised to 300°C, the vacuum is evacuated to 9 mbar, and the temperature of the source bottle containing the platinum source (methylcyclopentadienyl)-trimethylplatinum (MeCpPtMe3, 99%) is raised to 75°C to achieve the saturated vapor pressure of the platinum source. The deposition cycle steps are as follows: the source bottle is opened for 300 ms, the platinum source is supplied, exposed for 5 s to allow the platinum source to be adsorbed onto the 3D-PBG, then N2 is introduced for 10 s to remove the unadsorbed platinum source, then O2 is introduced for 2 s to react with the platinum source for 2 s, and then immediately purified with N2 for 15 s to remove other substances produced by the reaction, thus completing one platinum deposition cycle. 70 ALD platinum deposition cycles are performed to obtain a B-doped graphene porous membrane with deposited platinum nanoparticles, weighing 315.32 mg, with a platinum loading of 20 μg / cm³. 2 ;

[0060] (5) Dilute the DuPont Nafion D520 solution in the ion exchange resin solution to 2 mg / ml with anhydrous isopropanol; cut the B-doped graphene porous film deposited with platinum nanoparticles in step (4) into 2.2 cm × 2.2 cm pieces, and then place them in an electrostatic sprayer. Use the diluted ion exchange resin solution to uniformly electrostatically spray the cut B-doped graphene porous film deposited with platinum nanoparticles. The spray loading is 30 μg / cm. 2 Drying at 80℃ for 30 minutes yields a platinum nanocrystalline electrode material supported on a B-doped graphene porous film (referred to as Pt / 3D-PBG), which is used as the anode.

[0061] Comparative Example 1

[0062] The pressure inside the arc cavity in step (3) was set to 10 kPa, 20 kPa, and 40 kPa, respectively. The remaining operations were the same as steps (1)-(3) of Example 1, "1.1, a method for preparing platinum nanocrystalline electrode material supported by B-doped graphene porous film as cathode". The B-doped graphene porous films (3D-PBG) prepared under different pressures were obtained. The 3D-PBG prepared under different pressures were detected by scanning electron microscopy and Raman spectroscopy. The results are as follows. Figure 4 , Figure 5 As shown.

[0063] Comparative Example 2

[0064] The arc stripping time in step (3) was set to 20s and 40s respectively. The remaining operations were the same as those in Example 1, “1.1, a method for preparing a B-doped graphene porous film loaded with platinum nanocrystal electrode material as a cathode”. The B-doped graphene porous film loaded with platinum nanocrystal electrode material (Pt / 3D-PBG) prepared with different arc stripping times were obtained respectively.

[0065] Application and performance testing

[0066] Application Example 1:

[0067] The Pt / 3D-PBG prepared in Example 1 was applied to the construction of an ultra-low platinum content fuel cell electrode. Pt / 3D-PBG can be used as both the cathode and anode of the fuel cell; when used as the cathode, the platinum (Pt) loading of Pt / 3D-PBG is 80 μg / cm³. 2 When used as an anode, the platinum (Pt) loading of Pt / 3D-PBG is 20 μg / cm³. 2 The Pt / 3D-PBG method was used to fabricate fuel cell electrodes, and the operation steps are as follows:

[0068] The Pt / 3D-PBG prepared in 1.1 of Example 1 is used as the cathode, and the Pt / 3D-PBG prepared in 1.2 of Example 1 is used as the anode in the preparation of fuel cell electrodes. The operation steps are as follows:

[0069] (i) The Pt / 3D-PBG prepared in Example 1 as the cathode and the Pt / 3D-PBG as the anode were placed on both sides of the proton exchange membrane, and placed in a hot press. The hot pressing transfer was performed at 135°C and 480 kgf for 180 s to transfer the Pt / 3D-PBG onto the proton exchange membrane. After cooling, the aluminum foil was peeled off.

[0070] (ii) Place the gas diffusion layer on both sides of the proton exchange membrane obtained after the transfer in step (i), and hot press it at 135°C and 15 kgf for 10 s to make a proton exchange membrane electrode (MEA), which is an ultra-low platinum fuel cell electrode.

[0071] Performance testing:

[0072] 1. Place the proton exchange membrane electrode (MEA) prepared in step (ii) above into the battery fixture and test it on an 850e fuel cell test station. The battery is first swept from open circuit voltage to 0.2V at 80℃ in hydrogen / oxygen (400 / 400 sccm) until it reaches stability. Then, its IV polarization curve and power density curve are tested in hydrogen / air (400 / 1000 sccm) as shown below. Figure 3 As shown. From Figure 3 It can be seen that the Pt / 3D-PBG prepared by this invention can be used as both a cathode and an anode in a battery, with a total platinum loading of 100 μg / cm³ at both the anode and cathode. 2 Under these conditions, it has 0.9W cm -2 Performance.

[0073] 2. The Pt / 3D-PBG (30s) obtained in step (3) of Example 1, and the Pt / 3D-PBG (20s, 40s) prepared with different arc stripping times in Comparative Example 2 were used as cathodes, with a platinum loading of 80 μg / cm³ for each cathode. 2 At a platinum loading of 20 μg / cm 2 As the anode, a proton exchange membrane electrode (MEA) was prepared according to steps (i) and (ii) of Application Example 1. The MEA was placed in a battery fixture and tested on an 850e fuel cell test station. The battery was first swept from open-circuit voltage to 0.2 V at 80°C in a hydrogen / oxygen (400 / 400 sccm) environment until stability was achieved. Then, its IV polarization curve and power density curve were tested in a hydrogen / air (400 / 1000 sccm) environment, as shown below. Figure 6 As shown, this indicates that the performance is optimal when the arc stripping time is 30 s.

[0074] 3. A commercially available platinum-carbon membrane electrode was used, with platinum loadings of 200 μg / cm³ for both the anode and cathode. 2 The membrane electrode assembly (MEA) was placed in the battery fixture and tested on an 850e fuel cell test station. The battery was first swept from open-circuit voltage to 0.2 V at 80°C in a hydrogen / oxygen (400 / 400 sccm) environment until it reached stability. Then, its IV polarization curve and power density curve were tested in a hydrogen / air (400 / 1000 sccm) environment. The results are as follows: Figure 7 As shown. From Figure 7 It can be seen that the platinum loading of the anode in this invention is 20 μg / cm³. 2 Cathode platinum loading 80 μg / cm 2 ( Figure 3 When used as an electrode, and with a commercial Pt / C catalyst, the anode and cathode each have a concentration of 200 μg / cm³. 2 While exhibiting the same performance, the platinum loading of the electrode in this invention is far lower than that of commercial catalysts.

[0075] Figure 2 (a) and (b) are SEM images of the B-doped graphene porous film (3D-PBG) prepared in step (3) of Example 1, and the B-doped graphene obtained by SEM testing. Figure 2 (aⅠ) is the EDS test corresponding to (a), which shows that this carbon material contains B element and that the element is evenly distributed.

[0076] Figure 4These are SEM images of beta-doped graphene porous films (3D-PBG) prepared under different pressures; (a) 3D-PBG prepared at 10 kPa, (b) 3D-PBG prepared at 20 kPa, (c) 3D-PBG prepared at 30 kPa, and (d) 3D-PBG prepared at 40 kPa. It can be seen that the morphology of the carbon material is only completely graphene sheet at pressures above 30 kPa. However, because the graphitization degree of graphene is high at 40 kPa, it will affect the platinum deposition efficiency, so 30 kPa is optimal. The defect degree of graphene was characterized by Raman spectroscopy at 532.0 nm. Figure 5 This indicates that at 10 kPa, 20 kPa, 30 kPa, and 40 kPa, I D / I G The values ​​are 1.01, 0.83, 0.73, and 0.56, respectively.

[0077] The foregoing description of specific exemplary embodiments of the invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A boron-doped graphene porous film-supported platinum nanocrystalline electrode material, characterized in that: Boron-doped graphene porous membrane supports platinum nanocrystalline electrode material. The graphene is deposited on aluminum foil by arc discharge method, and has abundant porosity and high graphitization, providing efficient mass transfer channels and excellent corrosion resistance. On this basis, platinum nanocrystals are deposited as catalyst layer for fuel cell. The preparation method of the B-doped graphene porous film-supported platinum nanocrystalline electrode material includes the following steps: (1) Use aluminum foil cleaned with ethanol as a porous graphene deposition substrate; (2) A graphite rod is used as the raw material for arc exfoliation of graphene, and a hole is drilled on one end face of the graphite rod. Then, a boron source is injected into the hole. (3) Adhere the porous graphene deposition substrate obtained in step (1) to the top of the arc chamber, place the graphite rod with boron source injected in step (2) at the anode end of the arc chamber, take a graphite rod, sharpen one end, and place it at the cathode end of the arc chamber; after evacuation, introduce argon and hydrogen gas to make the pressure ≥30kPa, and then perform arc stripping for 30-35s to obtain B-doped graphene porous film. (4) The B-doped graphene porous film obtained in step (3) is placed in the reaction chamber of atomic layer deposition. Under ALD conditions, the temperature of the chamber is raised to 297-300℃, vacuum is drawn, and the temperature of the source bottle with platinum source is raised to the temperature that can reach the saturated vapor pressure of the platinum source for deposition cycle. Then, platinum deposition cycle is performed to obtain B-doped graphene porous film with deposited platinum nanoparticles. (5) The B-doped graphene porous film with deposited platinum nanoparticles obtained in step (4) is sprayed with an ion exchange resin solution and dried to obtain the B-doped graphene porous film loaded with platinum nanocrystals electrode material. The platinum loading of the B-doped graphene porous film loaded with platinum nanocrystals electrode material is 20-80 μg / cm³. 2 .

2. The B-doped graphene porous film-supported platinum nanocrystalline electrode material according to claim 1, characterized in that: The amount of boron source injected in step (2) is 291.5 mg of boron source injected per 1 square centimeter of hole volume; the diameter of the hole is 0.5 cm and the depth is 2 cm; the boron source in step (2) is one of boric acid, boron carbide, fluoroboric acid or metaboric acid.

3. The platinum nanocrystalline electrode material supported on a boron-doped graphene porous film according to claim 1, characterized in that: The vacuuming in step (3) is to maintain a vacuum level of ≤3.0Pa; the hydrogen flow rate in step (3) is 300sccm and the argon flow rate is 188sccm.

4. The platinum nanocrystalline electrode material supported on a boron-doped graphene porous film according to claim 1, characterized in that: The vacuum in the atomic layer deposition reaction chamber in step (4) is evacuated to a vacuum level of 7-10 mbar; the platinum source in step (4) is methylcyclopentadienyl-trimethylplatinum; and the temperature at which the saturated vapor pressure of the platinum source can be reached is 75°C.

5. The platinum nanocrystalline electrode material supported on a boron-doped graphene porous film according to claim 1, characterized in that: The platinum deposition cycle described in step (4) is as follows: open the source bottle for 300 ms, supply the platinum source, expose for 5 s to allow the platinum source to be adsorbed onto the B-doped graphene porous film, then introduce N2 for 10 s to remove the unadsorbed platinum source, then introduce O2 for 2 s to react with the platinum source, and then immediately purify with N2 for 15 s to remove other substances produced by the reaction, thus completing one platinum deposition cycle.

6. The platinum nanocrystalline electrode material supported on a boron-doped graphene porous film according to claim 1, characterized in that: The ion exchange resin solution mentioned in step (5) is an ion exchange resin solution diluted with an alcohol solvent to a concentration of 2 mg / ml; the spraying loading is 5-30 μg / cm³. 2 The drying time is 30 minutes.

7. The platinum nanocrystalline electrode material supported on a boron-doped graphene porous film according to claim 6, characterized in that: The ion exchange resin solution is one of DuPont Nafion solutions D520, D521, D1020, D1021, or D2020; the content of the ion exchange resin solution is 5%-20%; the spray loading is 20 μg / cm³. 2 The alcohol solvent is ethanol or isopropanol.

8. The application of the B-doped graphene porous membrane-supported platinum nanocrystalline electrode material as described in any one of claims 1-7 in the construction of ultra-low platinum content fuel cell electrodes, characterized in that: The B-doped graphene porous membrane-supported platinum nanocrystalline electrode material can serve as both the cathode and anode of a fuel cell; when used as a cathode, the platinum loading of the B-doped graphene porous membrane-supported platinum nanocrystalline electrode material is 50-80 μg / cm³. 2 When used as the anode, the platinum loading of the B-doped graphene porous film-supported platinum nanocrystalline electrode material is 20 μg / cm³. 2 .

9. The application as described in claim 8, characterized in that, The operation includes the following steps: (i) Platinum nanocrystal electrode material supported by B-doped graphene porous membrane as cathode and platinum nanocrystal electrode material supported by anode is placed on both sides of proton exchange membrane and hot-pressed at 135°C and 480 kgf for 180 s to transfer the platinum nanocrystal electrode material supported by B-doped graphene porous membrane onto the proton exchange membrane. (ii) Place the gas diffusion layer on both sides of the proton exchange membrane obtained after the transfer in step (i), and hot press it at 135°C and 15 kgf for 10 s to make the proton exchange membrane electrode, i.e., the ultra-low platinum fuel cell electrode.

Images