A platinum-based high-entropy intermetallic compound, a preparation method thereof and application thereof as a hydrogen fuel cell cathode catalyst

Abstract

The application discloses a platinum-based high-entropy intermetallic compound and a preparation method and application thereof as a hydrogen fuel cell cathode catalyst, and belongs to the field of fuel cells.The preparation method comprises the following steps: S01, adding platinum salt, at least five other metal salts and a nitrogen-rich organic compound into an organic solvent, uniformly mixing, and obtaining a metal precursor mixed solution; S02, adding a carbon carrier into the metal precursor mixed solution, fully mixing, drying, collecting, and obtaining a precursor; and S03, heat treating the dried precursor under a reducing atmosphere, and performing heat preservation treatment, so as to obtain the platinum-based high-entropy intermetallic compound.The preparation method is simple, low in cost and good in repeatability, the prepared catalyst has the advantages of uniform particle size and high oxygen reduction activity, and has a good development prospect in the field of hydrogen fuel cell catalyst applications.

Description

Technical Field

[0001] This application relates to a platinum-based high-entropy intermetallic compound and its preparation method, as well as its application as a cathode catalyst in hydrogen fuel cells, belonging to the field of fuel cells. Background Technology

[0002] Hydrogen energy, as a clean and efficient secondary energy source, plays a vital role in upgrading my country's energy structure and reducing its heavy reliance on traditional fossil fuels. Proton exchange membrane fuel cells (PEMFCs) are highly efficient hydrogen-to-electricity conversion devices and represent an important application of hydrogen energy in the transportation sector.

[0003] The oxygen reduction reaction (ORR) kinetics at the cathode of a PEMFC are relatively slow, typically requiring the use of the precious metal platinum (Pt) as a catalyst. However, Pt is scarce and expensive in the Earth's crust, and pure Pt catalysts have poor durability, which greatly limits the commercialization of fuel cell vehicles. Therefore, the development of Pt-based alloy catalysts with high catalytic activity and durability has attracted widespread attention.

[0004] By introducing other inexpensive metal elements to modulate the electronic structure of platinum atoms on the surface, the intrinsic catalytic activity of platinum can be improved, thereby reducing the cost of the catalyst. Early molecular dynamics simulations and polycrystalline bulk experiments have shown that Pt-transition metal alloys and Pt-lanthanide metal alloys are considered two types of binary alloy systems with high oxygen reduction activity. However, most reported Pt-transition metal alloy catalysts are solid solution structures. Under fuel cell operating conditions, due to the low redox potential of transition metals, they are prone to leaching from the alloy structure, ultimately severely damaging the catalyst's lifetime. Furthermore, the standard reduction potential of lanthanides (approximately -2.3 V) is much lower than that of Pt (approximately +1.19 V). Common reducing agents used in conventional wet synthesis are insufficient to achieve co-reduction of the two metals, and currently, there are few reported methods for the chemical synthesis of Pt-lanthanide metal alloy catalysts.

[0005] Intermetallic compounds, which have recently gained widespread attention, differ from solid solutions in that their crystal lattice structure differs from that of their constituent elements. Their ordered atomic structure facilitates the separation of active sites, and their electronic structure can be modulated, making them potential catalysts. However, current research on intermetallic compound catalysts largely focuses on binary alloys. High-entropy alloys, or multi-component alloys, refer to novel alloy materials made of four or more metallic elements, possessing excellent mechanical, physical, and chemical properties. Furthermore, high-entropy alloys contain a diverse range of elements, allowing for synergistic catalytic effects among the multi-component metals, resulting in superior catalytic performance. Therefore, combining the advantages of intermetallic compounds and high-entropy alloys in chemical synergy can lead to the development of oxygen reduction catalysts with higher intrinsic activity for application in hydrogen fuel cells.

[0006] Compared to disordered solid solution structures, the high order and strong interactions between metal elements in intermetallic compounds are considered to stabilize the alloy structure and prevent the precipitation of metal components during fuel cell operation, effectively improving the catalyst's cycle stability under fuel cell conditions. However, due to significant differences in the physical properties of the various metal components, such as atomic radius and reduction potential, catalysts prepared by conventional wet synthesis suffer from low lattice order or even phase separation, making it difficult to synthesize ordered high-entropy alloy nanoparticles with a single intermetallic compound phase. Therefore, preparing single-phase high-entropy intermetallic compound nanoparticles with controllable catalyst particle size is a major challenge. Summary of the Invention

[0007] According to the first aspect of this application, a method for preparing a platinum-based high-entropy intermetallic compound is provided. This method first disperses a metal precursor and a nitrogen-rich organic compound in a solvent, then adds a conductive support, mixes and dries the mixture. The dried precursor mixture is then heat-treated in a tube furnace under a reducing atmosphere to obtain the platinum-based high-entropy intermetallic compound. This method is simple, scalable, and has good universality.

[0008] A method for preparing a platinum-based high-entropy intermetallic compound, the method comprising:

[0009] S01: Platinum salt, at least five other metal salts, and nitrogen-rich organic compounds are added to an organic solvent and mixed evenly to obtain a mixed solution of metal precursors.

[0010] SO2: Add carbon support to the mixed solution of metal precursors, mix thoroughly, dry, and collect to obtain the precursor;

[0011] S03: The dried precursor is heat-treated in a reducing atmosphere and then kept at that temperature to obtain a platinum-based high-entropy intermetallic compound.

[0012] Optionally, in step S01, the platinum salt is selected from at least one of platinum chloride, chloroplatinic acid, and platinum acetylacetonate;

[0013] The other metal salts include salts of transition metals or salts of lanthanides.

[0014] The transition metal element is selected from iron, cobalt, nickel, copper, manganese, or zinc;

[0015] The lanthanide metal elements are selected from lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, or lutetium;

[0016] The salt of the transition metal element is selected from the chloride salt, nitrate salt or acetylacetone salt of the corresponding transition metal element;

[0017] The salts of the lanthanide metal elements are selected from the chloride salts, nitrate salts, or acetylacetone salts corresponding to the lanthanide metal elements.

[0018] Preferably, at least five other metal salts are selected. When the other metal salts are salts of transition metal elements, salts corresponding to five different transition elements are selected, such as five different transition elements: iron, cobalt, nickel, copper, and zinc. In this case, ferric chloride, cobalt chloride, nickel chloride, copper chloride, and zinc chloride are selected. When the other metal salts are salts of lanthanide metal elements, salts corresponding to five different lanthanide metal elements are selected, such as five different lanthanide metal elements: cerium, samarium, gadolinium, terbium, and dysprosium. In this case, cerium chloride, samarium chloride, gadolinium chloride, terbium chloride, and dysprosium chloride are selected.

[0019] Optionally, the salts of transition metal elements include iron salts, cobalt salts, nickel salts, copper salts, manganese salts, and zinc salts. The iron salt is at least one of ferric chloride, ferric nitrate, or ferric acetylacetonate; the cobalt salt is at least one of cobalt chloride, cobalt nitrate, or cobalt acetylacetonate; the nickel salt is at least one of nickel chloride, nickel nitrate, or nickel acetylacetonate; the copper salt is at least one of copper chloride, copper nitrate, or copper acetylacetonate; the manganese salt is at least one of manganese chloride, manganese nitrate, or manganese acetylacetonate; and the zinc salt is at least one of zinc chloride, zinc nitrate, or zinc acetylacetonate.

[0020] Optionally, the salts of lanthanide metals include lanthanum salts, cerium salts, praseodymium salts, neodymium salts, samarium salts, europium salts, gadolinium salts, terbium salts, dysprosium salts, holmium salts, erbium salts, thulium salts, ytterbium salts, and lutetium salts. The lanthanum salt is at least one of lanthanum chloride, lanthanum nitrate, or lanthanum acetylacetonate; the cerium salt is at least one of cerium chloride, cerium nitrate, or cerium acetylacetonate; the praseodymium salt is at least one of praseodymium chloride, praseodymium nitrate, or praseodymium acetylacetonate; the neodymium salt is at least one of neodymium chloride, neodymium nitrate, or neodymium acetylacetonate; the samarium salt is at least one of samarium chloride, samarium nitrate, or samarium acetylacetonate; the europium salt is at least one of europium chloride, europium nitrate, or europium acetylacetonate; and the gadolinium salt is at least one of gadolinium chloride, gadolinium nitrate, or gadolinium acetylacetonate. The terbium salt is at least one of terbium chloride, terbium nitrate, or terbium acetylacetonate; the dysprosium salt is at least one of dysprosium chloride, dysprosium nitrate, or dysprosium acetylacetonate; the holmium salt is at least one of holmium chloride, holmium nitrate, or holmium acetylacetonate; the erbium salt is at least one of erbium chloride, erbium nitrate, or erbium acetylacetonate; the thulium salt is at least one of thulium chloride, thulium nitrate, or thulium acetylacetonate; the ytterbium salt is at least one of ytterbium chloride, ytterbium nitrate, or ytterbium acetylacetonate; and the lutetium salt is at least one of lutetium chloride, lutetium nitrate, or lutetium acetylacetonate.

[0021] Optionally, in step S01, the molar ratio of the platinum salt and at least five other metal salts is 1 to 5:1.

[0022] At least five other metal salts were used in equal molar ratios;

[0023] In the mixed solution of metal precursors, the total concentration of metal salts is 1~100mM.

[0024] In at least five other metal salts, the molar ratio of their amounts is equal. Taking the salts of five transition metal elements as an example, their molar ratio is preferably 1:1:1:1:1; taking the salts of five lanthanide metal elements as an example, their molar ratio is preferably 1:1:1:1:1.

[0025] Optionally, the molar ratio of the sum of the platinum salt and at least five other metal salts is selected from any value of 1:1, 2:1, 3:1, 4:1, 5:1 or any range between both.

[0026] Optionally, in the mixed solution of metal precursors, the total concentration of the metal salt is selected from any value or a range between 1 mM, 5 mM, 100 mM, 20 mM, 30 mM, 40 mM, 50 mM, 60 mM, 70 mM, 80 mM, 90 mM, and 100 mM.

[0027] Optionally, in step S01, the nitrogen-rich organic compound is selected from at least one of cyanamide (CN2H2), dicyandiamide (C2N4H4), melamine (C3N6H6), and ethylenediamine (C2H8N2);

[0028] The molar ratio of the nitrogen-rich organic compound to the platinum salt is 10~20:1.

[0029] Preferably, the nitrogen-rich organic compound is cyanamide (CN2H2).

[0030] Preferably, the molar ratio of the nitrogen-rich organic compound to the platinum salt is 15:1.

[0031] Optionally, the molar ratio of the nitrogen-rich organic compound to the platinum salt is selected from any value of 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, 16:1, 17:1, 18:1, 19:1, 20:1 or any range between the two.

[0032] In this application, nitrogen-rich organic compounds are used as additives and thoroughly mixed with metal precursors. During subsequent heat treatment, all metal atoms are uniformly distributed within the carbon-nitrogen network structure due to the strong complexation effect of the nitrogen bonds in the nitrogen-rich organic compounds. After reaching the thermal decomposition temperature of the nitrogen-rich organic compounds under a reducing atmosphere, platinum is preferentially reduced to metallic platinum nanoparticles. The platinum nanoparticles dispersed around the nitrogen-rich organic compounds drive the remaining metal atoms and platinum nanoparticles to form a high-entropy solid solution alloy structure. After further heat treatment, the disordered solid solution structure transforms into an ordered intermetallic compound structure.

[0033] Optionally, in step S01, the organic solvent is a mixture of water and alcohol;

[0034] The alcohol is selected from at least one of ethanol and isopropanol.

[0035] The preferred volume ratio of water to alcohol is 1:1.

[0036] Optionally, in step S02, the carbon support is selected from at least one of Vulcan XC72, Vulcan XC72R, Ketjen Black EC300, Ketjen Black EC600JD, Ketjen Black ECP600JD, and Black Pearls 2000.

[0037] Carbon carrier is preferred as the conductive carrier, with Ketjen Black ECP600JD (KB600) being the preferred choice.

[0038] Optionally, the mass ratio of platinum in the carbon support and the platinum salt is 7:3.

[0039] Optionally, in step S03, the reducing atmosphere is a mixed atmosphere containing hydrogen and inactive gases;

[0040] The inactive gas is selected from at least one of nitrogen, argon, or helium.

[0041] The preferred volume ratio of hydrogen to inactive gas is 1:9.

[0042] Optionally, in step S03, the temperature of the heat treatment is 500~600℃, and the time of the heat treatment is 1~120min.

[0043] Preferably, the heat treatment temperature is 600°C and the heat treatment time is 60 minutes.

[0044] Optionally, the temperature of the heat treatment is selected from any value or a range between 500℃, 510℃, 520℃, 530℃, 540℃, 550℃, 560℃, 570℃, 580℃, 590℃, and 600℃.

[0045] Optionally, the heat treatment time is selected from any value or a range between 1 min, 5 min, 10 min, 20 min, 50 min, 60 min, 80 min, 100 min, 110 min, and 120 min.

[0046] Optionally, the set temperature for heat treatment is reached by programmed heating, with the heating rate preferably being 10°C / min.

[0047] Optionally, the insulation temperature is 700~900℃, and the insulation time is 1~120min.

[0048] Preferably, the insulation temperature is 800℃ and the insulation time is 120 minutes.

[0049] Optionally, the insulation temperature is selected from any value or a range between 700℃, 720℃, 750℃, 780℃, 800℃, 820℃, 850℃, 880℃, and 900℃.

[0050] Optionally, the heat preservation time is selected from any value or a range between 1 min, 5 min, 10 min, 20 min, 50 min, 60 min, 80 min, 100 min, 110 min, and 120 min.

[0051] As a preferred embodiment, the method for preparing the platinum-based high-entropy intermetallic compound includes:

[0052] S01: Preparation of precursor dispersion: Add the precursor metal salts of platinum source and other metal sources to the organic solvent in proportion and sonicate for at least 30 minutes, then add them to the nitrogen-rich organic compound in proportion and sonicate for at least 30 minutes.

[0053] S02: Add a conductive carrier to the precursor mixture obtained in step S01, stir magnetically for at least 120 minutes to mix thoroughly, and then dry and collect it in a vacuum drying oven at 80ºC.

[0054] S03: The dried precursor collected in step S02 is transferred to a crucible and placed in a tube furnace. A reducing atmosphere is introduced for heating and holding treatment, and then the mixture is naturally cooled to obtain a platinum-based high-entropy intermetallic compound.

[0055] This application directly obtains a metal precursor by mixing a metal salt, a conductive support, and a nitrogen-rich organic compound in a solution and then drying it, without relying on stabilizers, organic ligands, or metal-organic frameworks. The nitrogen bonds in the nitrogen-rich organic compound introduced in this application can complex and distribute all metal atoms, allowing all metal atoms to be reduced on the same platinum particle to first form a high-entropy alloy with a relatively low degree of order in a solid solution structure. Further thermal insulation then transforms this alloy into a more ordered intermetallic compound. This results in superior electrochemical activity and cycle durability, demonstrating excellent battery performance in practical hydrogen fuel cells.

[0056] According to a second aspect of this application, a platinum-based high-entropy intermetallic compound is provided.

[0057] The platinum-based high-entropy intermetallic compound prepared by the preparation method described above.

[0058] This platinum-based high-entropy intermetallic compound remains relatively stable in harsh electrochemical environments. By alloying Pt with transition metals M (M=Fe, Co, Ni, Cu, Zn, etc.) or lanthanide metals Ln (Ln=Ce, Sm, Gd, Tb, Dy, etc.), the multi-component metals exert a synergistic effect, which regulates the electronic structure of Pt atoms on the surface, improves the intrinsic activity of the catalyst, and thus reduces the amount of precious metals used, ultimately achieving cost reduction.

[0059] The prepared high-entropy alloy catalyst nanoparticles are uniformly loaded on a conductive support, exhibiting consistent size and no compositional segregation. As a single-phase intermetallic compound, free of other impurities, with an average particle size of less than 5 nanometers, it meets the requirements for hydrogen fuel cell cathode catalysts. It possesses advantages such as high oxygen reduction activity, demonstrating promising development prospects in the field of hydrogen fuel cell catalysts.

[0060] According to a third aspect of this application, an application of a platinum-based high-entropy intermetallic compound is provided.

[0061] The above-mentioned platinum-based high-entropy intermetallic compounds are used as cathode catalysts for hydrogen fuel cells.

[0062] The aforementioned platinum-based high-entropy intermetallic compound, when used as a cathode catalyst in a hydrogen fuel cell for the oxygen reduction reaction, can accelerate the oxygen reduction reaction at the cathode. Systematic electrochemical experiments show that the synthesized high-entropy intermetallic compound catalyst exhibits significantly better oxygen reduction activity in the acidic electrolyte 0.1 M perchloric acid than the commercial catalyst 40%Pt / C, while also demonstrating excellent electrochemical stability and promising potential for fuel cell applications.

[0063] The beneficial effects that this application can produce include:

[0064] The method for preparing platinum-based high-entropy intermetallic compounds provided in this application has the advantages of being simple, easy to achieve large-scale preparation, low cost, and good reproducibility. The prepared high-entropy alloy catalyst nanoparticles are uniformly loaded on a conductive support, with uniform size and no component segregation; they are single-phase intermetallic compounds without other impurities, and have an average particle size of less than 5 nanometers, meeting the requirements for hydrogen fuel cell cathode catalysts. When used as a hydrogen fuel cell cathode catalyst for the oxygen reduction reaction, it can accelerate the oxygen reduction reaction at the cathode. Systematic electrochemical experiments show that the synthesized high-entropy intermetallic compound catalyst has significantly better oxygen reduction activity in the acidic electrolyte 0.1 M perchloric acid than the commercial catalyst 40%Pt / C, while also exhibiting excellent electrochemical stability and good potential for fuel cell applications. Attached Figure Description

[0065] Figure 1 This is the X-ray diffraction pattern (XRD) of Pt-FeCoNiCuZn / KB600 in Example 1 of the present invention.

[0066] Figure 2 This is a high-resolution electron microscope (HRTEM) image of Pt-FeCoNiCuZn / KB600 in Example 1 of this invention.

[0067] Figure 3 This is a polarization curve of Pt-FeCoNiCuZn / KB600 and a commercial catalyst of 40%Pt / C in Example 1 of this invention;

[0068] Figure 4 This is a bar chart comparing the area ratio activity and mass ratio activity of Pt-FeCoNiCuZn / KB600 and the commercial catalyst 40%Pt / C in Example 1 of this invention.

[0069] Figure 5The images show accelerated aging polarization curves of Pt-FeCoNiCuZn / KB600 and the commercial catalyst 40%Pt / C in Example 1 of this invention, where image a corresponds to Pt-FeCoNiCuZn / KB600 and image b corresponds to the commercial catalyst 40%Pt / C.

[0070] Figure 6 The discharge curve and power density diagram of Pt-FeCoNiCuZn / KB600 and commercial catalyst 40%Pt / C in a hydrogen-air fuel cell are measured at a relative atmospheric pressure of 100 kPa in Example 1 of this invention.

[0071] Figure 7 This is the X-ray diffraction pattern (XRD) of Pt-CeSmGdTbDy / KB600 in Embodiment 2 of the present invention.

[0072] Figure 8 This is a high-resolution electron microscope (HRTEM) image of Pt-CeSmGdTbDy / KB600 in Embodiment 2 of the present invention.

[0073] Figure 9 This is a polarization curve of Pt-CeSmGdTbDy / KB600 and a commercial catalyst of 40%Pt / C in Example 2 of this invention;

[0074] Figure 10 This is a bar chart comparing the area ratio activity and mass ratio activity of Pt-CeSmGdTbDy / KB600 and the commercial catalyst 40%Pt / C in Example 2 of this invention.

[0075] Figure 11 The accelerated aging polarization curves of Pt-CeSmGdTbDy / KB600 and commercial catalyst 40%Pt / C in Example 2 of the present invention are shown in Figure a, where Figure a corresponds to Pt-CeSmGdTbDy / KB600 and Figure b corresponds to commercial catalyst 40%Pt / C.

[0076] Figure 12 The discharge curves and power density diagrams of Pt-CeSmGdTbDy / KB600 and the commercial catalyst 40%Pt / C in Example 2 of this invention were measured in a hydrogen-air fuel cell at a relative atmospheric pressure of 100 kPa. Detailed Implementation

[0077] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0078] Unless otherwise specified, all raw materials used in the embodiments of this application were purchased through commercial channels.

[0079] Unless otherwise specified, all test methods are standard and all instrument settings are those recommended by the manufacturer.

[0080] The conductive carrier KB600 is Ketjen Black ECP600JD.

[0081] The commercial catalyst for 40% Pt / C is Johnson Matthey HiSPEC4000.

[0082] The analysis method in the embodiments of this application is as follows:

[0083] Powder X-ray diffraction (XRD) analysis was performed using an Empyrean S3 as an X-ray diffractometer with Cu Kα (λ=1.5418Å) as the radiation source at a scan rate of 10° / min and a scan range of 10° to 90°.

[0084] SEM analysis was performed using a Sigma 560 scanning electron microscope, and TEM testing of the samples was performed using a JEOL F200 field emission transmission electron microscope.

[0085] Electrochemical tests were conducted using the Chenhua CHI760E electrochemical workstation, and fuel cell tests were conducted using the Qunyi 850e fuel cell test bench.

[0086] Example 1

[0087] A method for preparing platinum-based high-entropy intermetallic compound electrocatalysts: First, a metal precursor salt is dispersed in an organic solvent. Then, a nitrogen-rich organic compound and a conductive support are added sequentially, mixed, and dried to obtain the precursor. The precursor is then annealed to obtain the platinum-based high-entropy intermetallic compound electrocatalyst. The nanoscale high-alloy components are supported on the conductive support KB600. The high-entropy intermetallic compounds include the metal elements platinum, iron, cobalt, nickel, copper, and zinc. This embodiment prepares the nanoscale high-entropy intermetallic compound through the following steps:

[0088] S01: Preparation of precursor dispersion: Six precursor metal salts—chloroplatinic acid, ferric chloride, cobalt chloride, nickel chloride, copper chloride, and zinc chloride—were added to an organic solvent at a total molar ratio of platinum metal to other transition metals of 1:1, and the mixture was ultrasonically mixed for 30 minutes. The molar ratios of the other five transition metals were all equal. The organic solvent consisted of water and ethanol in a 1:1 volume ratio. Then, cyanamide was added to the precursor solution at a molar ratio of cyanamide to platinum precursor of 15:1, and the mixture was ultrasonically mixed for 30 minutes. The total concentration of the metal salts was 50 mM.

[0089] S02: According to the mass ratio of conductive carrier KB600 to platinum added to the platinum salt, the corresponding mass of conductive carrier KB600 is added to the precursor mixture obtained in step S01. After being fully mixed by magnetic stirring for 120 minutes, it is dried and collected in a vacuum drying oven at 80ºC.

[0090] S03: The dried precursor collected in step S02 is transferred to a crucible and placed in a tube furnace. A mixed atmosphere of hydrogen and nitrogen in a volume ratio of 1:9 is introduced for heat treatment at a heating rate of 10℃ / min, a heat treatment temperature of 600℃, and a heat treatment time of 60 min. The subsequent holding temperature is 800℃, and the holding time is 120 min. After holding, the mixture is allowed to cool naturally to obtain a platinum-based high-entropy intermetallic compound catalyst.

[0091] Step S03 yields the X-ray diffraction (XRD) pattern of Pt-FeCoNiCuZn / KB600 as shown below. Figure 1 As shown, a face-centered cubic (fcc) structure, different from that of platinum, is formed in a single-phase intermetallic compound. This structure matches the standard card L10PtFe (JCPDS 26-1139), confirming that a single-phase intermetallic compound has been formed.

[0092] The high-resolution electron microscope (HRTEM) image of Pt-FeCoNiCuZn / KB600 obtained in step S03 is as follows: Figure 2 As shown, the synthesized high-entropy alloy nanoparticles are uniformly dispersed on the conductive support KB600. The catalyst particles are uniform in size with an average particle size distribution of approximately 1.9 nanometers.

[0093] The content of each metal element in the Pt-FeCoNiCuZn / KB600 obtained in step S03 was measured using inductively coupled plasma atomic emission spectrometry (ICP-OES). The atomic percentages of the six metals, after conversion, are shown in Table 1. Pt accounts for the highest proportion of the total metal atoms at 46.4%, while the atomic percentages of the other five transition metals are relatively similar, ranging from 8.8% to 11.8%. This demonstrates that the percentage of atoms in high-entropy intermetallic compounds can be adjusted by changing the amount of introduced metal salts.

[0094] Table 1. Atomic percentage of metals in Pt-FeCoNiCuZn / KB600

[0095]

[0096] like Figure 3As shown, polarization curves of Pt-FeCoNiCuZn / KB600 and commercial 40%Pt / C (Johnson Matthey HiSPEC4000) catalysts were tested in oxygen-saturated 0.1 M perchloric acid with a saturated silver-silver chloride electrode as the reference electrode and a graphite carbon rod as the counter electrode. It can be seen that the performance of the synthesized catalyst in the 0.1 M perchloric acid acidic electrolyte is significantly better than that of the commercial catalyst 40%Pt / C. Its half-wave potential relative to the standard hydrogen electrode is 0.938V, while that of 40%Pt / C is 0.901V, proving that the material of this invention has a huge performance advantage as a cathode catalyst for hydrogen fuel cells.

[0097] like Figure 4 As shown in the bar chart, using a saturated silver-silver chloride electrode as the reference electrode and a graphite carbon rod as the counter electrode, the area-specific activity (SA) and mass-specific activity (MA) of Pt-FeCoNiCuZn / KB600 and the commercial catalyst 40%Pt / C after normalization with platinum in 0.1 M perchloric acid electrolyte are compared. It can be seen that at a potential of 0.90 V, the SA and MA of the material after normalization with platinum are significantly higher than those of the commercial catalyst 40%Pt / C. The MA at 0.90 V is 1.96 A / mgP, which is 5.76 times that of the commercial 40%Pt / C (0.34 A / mgP). The SA at 0.90 V is 1.81 mA / cm², which is 2.92 times that of the commercial 40%Pt / C (0.34 mA / cm²). This demonstrates that the material obtained by this invention (Pt-FeCoNiCuZn / KB600) has good intrinsic activity and excellent performance.

[0098] like Figure 5 As shown in Figure a, the half-wave potential of Pt-FeCoNiCuZn / KB600 only decreased by 2 millivolts after 30,000 cycles of accelerated aging. Figure 5 As shown in b, the half-wave potential of a commercial Pt / C catalyst decreases by 15 mV after accelerated aging via 30,000 cycles. Figure 5 a and Figure 5 b shows that the present invention has good cyclic stability in 0.1M perchloric acid.

[0099] Figure 6 Pt-FeCoNiCuZn / KB600 and a control commercial Pt / C catalyst (Johnson Matthey HiSPEC4000) were used as cathode catalysts, with a Pt metal loading of 0.2 mg. Pt / cm 2 The anode uses a commercial 60% Pt / C catalyst (Johnson Matthey HiSPEC9100), with a Pt metal loading of 0.05 mg. Pt / cm 2The discharge curves and power density diagrams for hydrogen-air fuel cells were measured at a relative atmospheric pressure of 100 kPa. Single fuel cells assembled using Pt-FeCoNiCuZn / KB600 and commercial Pt / C as cathode catalysts achieved power densities of 1.0 and 0.7 W / cm² at 0.65 V, respectively, with maximum power densities of 1.43 and 1.18 W / cm², respectively. This demonstrates that the hydrogen-air fuel cells constructed with the materials of this invention exhibit superior performance compared to commercial Pt / C catalysts.

[0100] Example 2

[0101] In step S01 of this embodiment, the metal salts used in preparing the precursor dispersion are replaced with chloroplatinic acid, cerium chloride, samarium chloride, gadolinium chloride, terbium chloride, and dysprosium chloride; the precursor metal salts of the six metal sources are added to the organic solvent in a molar ratio of platinum metal to the total of the other five lanthanide metals of 5:1. The other steps are the same as in Example 1, and the nanoscale high-entropy intermetallic compound Pt-CeSmGdTbDy / KB600 is obtained.

[0102] The obtained X-ray diffraction (XRD) pattern of Pt-CeSmGdTbDy / KB600 is as follows: Figure 7 As shown, a close-packed hexagonal (hcp) structure, different from that of platinum, is formed, which matches the standard card Pt5Sm (JCPDS 36-0079), confirming that a single-phase intermetallic compound has been formed.

[0103] The obtained high-resolution electron microscope (HRTEM) images of Pt-CeSmGdTbDy / KB600 are as follows: Figure 8 As shown, the synthesized high-entropy alloy nanoparticles are uniformly dispersed on the conductive support KB600. The catalyst particles are uniform in size with an average particle size distribution of approximately 4.5 nanometers.

[0104] The content of each metal element in the obtained Pt-CeSmGdTbDy / KB600 was measured using inductively coupled plasma atomic emission spectrometry (ICP-OES). The atomic percentages of the six metals after conversion are shown in Table 2. Pt accounts for the highest proportion of the total metal atoms, at 81.58%, while the other five lanthanide metals have relatively similar atomic percentages, ranging from 3.56% to 3.8%. This demonstrates that the atomic percentages in high-entropy intermetallic compounds can be adjusted by changing the amount of metal salt introduced.

[0105] Atomic percentage of metals in Pt-CeSmGdTbDy / KB600 (Table 2)

[0106]

[0107] like Figure 9 As shown, polarization curves of Pt-CeSmGdTbDy / KB600 and commercial 40%Pt / C catalysts were tested in oxygen-saturated 0.1 M perchloric acid using a saturated silver-silver chloride electrode as the reference electrode and a graphite carbon rod as the counter electrode. It is evident that the synthesized catalyst performs significantly better than the commercial 40%Pt / C catalyst in the 0.1 M perchloric acid acidic electrolyte. Its half-wave potential relative to the standard hydrogen electrode is 0.915 V, while that of 40%Pt / C is 0.901 V, demonstrating that the material of this invention has significant performance advantages as a cathode catalyst for hydrogen fuel cells.

[0108] like Figure 10 As shown in the bar chart, using a saturated silver-silver chloride electrode as the reference electrode and a graphite carbon rod as the counter electrode, the area-specific activity (SA) and mass-specific activity (MA) of Pt-CeSmGdTbDy / KB600 and the commercial catalyst 40%Pt / C after normalization with platinum in 0.1 M perchloric acid electrolyte are compared. It can be seen that at a potential of 0.90 V, the SA and MA of the material after normalization with platinum are significantly higher than those of the commercial catalyst 40%Pt / C. The MA at 0.90 V is 0.796 A / mgP, which is 2.34 times that of the commercial 40%Pt / C (0.34 A / mgP). The SA at 0.90 V is 1.4 mA / cm², which is 2.26 times that of the commercial 40%Pt / C (0.618 mA / cm²). This demonstrates that the material obtained by this invention (Pt-CeSmGdTbDy / KB600) exhibits excellent intrinsic activity.

[0109] like Figure 11 As shown in Figure a, the half-wave potential of Pt-CeSmGdTbDy / KB600 only decreased by 6 millivolts after 30,000 cycles of accelerated aging. Figure 11 As shown in b, the half-wave potential of a commercial Pt / C catalyst decreases by 15 mV after accelerated aging via 30,000 cycles. Figure 11 a and Figure 11 b shows that the present invention has good cyclic stability in 0.1M perchloric acid.

[0110] Figure 12 Pt-CeSmGdTbDy / KB600 and a control commercial Pt / C catalyst (Johnson Matthey HiSPEC4000) were used as cathode catalysts, with a Pt metal loading of 0.2 mg. Pt / cm 2 The anode uses a commercial 60% Pt / C catalyst (Johnson Matthey HiSPEC9100), with a Pt metal loading of 0.05 mg. Pt / cm 2The discharge curves and power density diagrams for hydrogen-air fuel cells were measured at a relative atmospheric pressure of 100 kPa. Single fuel cells assembled using Pt-CeSmGdTbDy / KB600 and commercial Pt / C as cathode catalysts exhibited power densities of 0.96 and 0.7 W / cm² at 0.65 V, respectively, and maximum power densities of 1.32 and 1.18 W / cm², respectively. This demonstrates that the hydrogen-air fuel cells constructed with the materials of this invention exhibit better performance than commercial Pt / C catalysts.

[0111] Therefore, the preparation method described above can prepare platinum-based high-entropy intermetallic compound catalysts with uniform particle size and high oxygen reduction activity. Furthermore, the preparation method of this invention is simple, easy to scale up, and has universality. Compared to the numerous reported disordered high-entropy alloy solid solution structures, the method of this invention can achieve various platinum-based ordered high-entropy intermetallic compounds with superior structural stability and effective control of each metal component, potentially providing new insights for finding superior platinum-based hydrogen fuel cell catalysts.

[0112] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for preparing a platinum-based high-entropy intermetallic compound, characterized in that, The preparation method includes: S01: Platinum salt, at least five other metal salts, and nitrogen-rich organic compounds are added to an organic solvent and mixed evenly to obtain a mixed solution of metal precursors. SO2: Add carbon support to the mixed solution of metal precursors, mix thoroughly, dry, and collect to obtain the precursor; S03: The dried precursor is heat-treated in a reducing atmosphere and then kept at that temperature to obtain a platinum-based high-entropy intermetallic compound. In step S01, the other metal salts include salts of transition metal elements or salts of lanthanide metal elements; The transition metal element is selected from iron, cobalt, nickel, copper, manganese, or zinc; The lanthanide metal elements are selected from lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, or lutetium; In step S01, the molar ratio of the platinum salt and at least five other metal salts is 1 to 5:

1. At least five other metal salts were used in equal molar ratios; In the mixed solution of metal precursors, the total concentration of metal salts is 1~100mM; In step S01, the nitrogen-rich organic compound is selected from at least one of cyanamide, dicyandiamide, melamine, and ethylenediamine; The molar ratio of the nitrogen-rich organic compound to the platinum salt is 10~20:1; In step S03, the temperature of the heat treatment is 500~600℃, and the time of the heat treatment is 1~120min; The heat preservation temperature is 700~900℃, and the heat preservation time is 1~120min.

2. The preparation method according to claim 1, characterized in that, In step S01, the platinum salt is selected from at least one of platinum chloride, chloroplatinic acid, and platinum acetylacetonate; The salt of the transition metal element is selected from the chloride salt, nitrate salt or acetylacetone salt of the corresponding transition metal element; The salts of the lanthanide metal elements are selected from the chloride salts, nitrate salts, or acetylacetone salts corresponding to the lanthanide metal elements.

3. The preparation method according to claim 1, characterized in that, In step S01, the organic solvent is a mixture of water and alcohol; The alcohol is selected from at least one of ethanol and isopropanol.

4. The preparation method according to claim 1, characterized in that, In step S02, the carbon support is selected from at least one of Vulcan XC72, Vulcan XC72R, Ketjen Black EC300, Ketjen Black EC600JD, Ketjen BlackECP600JD and Black Pearls 2000.

5. The preparation method according to claim 1, characterized in that, In step S03, the reducing atmosphere is a mixed atmosphere containing hydrogen and inactive gases; The inactive gas is selected from at least one of nitrogen, argon, or helium.

6. The platinum-based high-entropy intermetallic compound prepared by the preparation method according to any one of claims 1 to 5.

7. The application of the platinum-based high-entropy intermetallic compound of claim 6 as a cathode catalyst for hydrogen fuel cells.

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