Platinum-rare earth based intermetallic compound as well as rapid high-throughput preparation method and application thereof

Abstract

The invention discloses a platinum-rare earth based intermetallic compound as well as a rapid high-flux preparation method and application thereof. The method comprises the following steps: firstly, fully ultrasonically mixing a metal salt precursor, an inorganic auxiliary reagent and carbon black, freeze-drying the mixed solution, and then carrying out short-time Joule heating treatment to prepare the carbon-loaded platinum-rare earth-based intermetallic compound catalyst. Compared with reported preparation methods such as a physical metallurgy method and an electric arc melting method, the method has the advantages that the platinum-rare earth based intermetallic compound catalyst can be rapidly prepared at high flux, the prepared intermetallic compound is uniformly distributed on the surface of carbon black and is uniform in size and small in particle size, the problem of agglomeration of nano-particles is avoided, and meanwhile the platinum-rare earth based intermetallic compound catalyst has the advantages of being stable in structure, high in stability and the like. And the composite material has multiple active sites, shows excellent electrocatalytic activity on cathode hydrogen evolution reaction (HER) of an anion exchange membrane water electrolysis system, and has considerable energy application potential.

Description

Technical Field

[0001] The invention relates to a platinum-rare earth-based intermetallic compound and a rapid high-throughput preparation method and application thereof, belonging to the technical field of intermetallic compound preparation process. Background Art

[0002] Water electrolysis is an important method for preparing "green hydrogen" and a breakthrough in the supply of low-carbon clean hydrogen. Among them, anion exchange membrane water electrolysis (AEMWE) technology has attracted widespread attention due to its unique advantages such as low cost, high efficiency, and environmental friendliness. Its cathode hydrogen evolution reaction (HER) is crucial to the entire water electrolysis system. Unlike the direct supply of hydrogen protons in acidic media, the protons in alkaline HER are generated by breaking the H-OH bond (Volmer step, H2O+e - →H ad +OH - ), which slows down the supply of protons and leads to additional energy barriers. Even for commercial precious metal Pt / C catalysts, the activity of HER in alkaline media is two orders of magnitude lower than that in acidic media. Although great progress has been made in the research of non-precious metal catalysts, they are still inferior to platinum-based catalysts in catalytic activity and stability. Therefore, the development of platinum-based HER catalysts with low platinum loading and higher catalytic activity and stability is of great significance for the development of anion exchange membrane water electrolysis.

[0003] Alloying is considered to be an effective strategy to reduce the amount of platinum used and improve catalytic activity and stability. In particular, the introduction of low electronegativity metals has a significant effect on the electronic structure of platinum through the ligand effect, significantly enhancing the catalytic activity. 0-14 5d 0-1 6s 2 The electronic configuration of platinum can be effectively optimized by alloying different rare earth elements with platinum. Intermetallic compounds are a special type of alloy material with a certain stoichiometry and an ordered crystal structure. The ordered arrangement of platinum atoms and another metal atom enhances the interaction between the two atoms, improves the catalytic activity of the catalyst and the overall structural stability. Therefore, platinum-rare earth-based intermetallic compound materials have great application prospects in the field of energy electrocatalysis.

[0004] The methods reported so far for synthesizing platinum-rare earth-based metal intermetallic compounds mainly include tube furnace annealing, arc melting, physical metallurgy, magnetron sputtering, etc. However, these methods are not only energy-intensive but also have a long preparation cycle, and are not completely applicable to the preparation of sub-nanometer-scale catalysts. Therefore, exploring methods for rapidly preparing sub-nanometer-scale and uniformly sized platinum-rare earth-based metal intermetallic compounds is extremely challenging and of great significance. Summary of the invention

[0005] In order to solve the problems of the prior art, the purpose of the present invention is to provide a platinum-rare earth-based intermetallic compound and a rapid high-throughput preparation method and application thereof. The prepared intermetallic compound is of Pt2Ln type, and nanoparticles are uniformly loaded on the surface of carbon black with a uniform size of about 8nm. It exhibits excellent electrocatalytic activity in the cathode hydrogen evolution reaction of an anion exchange membrane water electrolysis system.

[0006] In order to solve the problems of the prior art, the present invention adopts the following technical solutions:

[0007] A rapid high-throughput preparation method for a platinum-rare earth-based intermetallic compound comprises the following steps:

[0008] (1) Preparation of carbon black supported by metal salt precursor

[0009] After uniformly mixing the platinum salt solution, the rare earth metal salt solution and the inorganic auxiliary reagent by ultrasonication, carbon black is added and ultrasonication is continued to obtain a metal salt precursor mixed solution;

[0010] (2) Preparation of platinum-rare earth-based intermetallic compounds by short-term continuous Joule heating

[0011] The metal salt precursor mixture is freeze-dried, and the freeze-dried powder is Joule heated. After the powder is heated, it is taken out, washed and dried to obtain a platinum-rare earth-based intermetallic compound.

[0012] As an improvement, the platinum salt described in step (1) is chloroplatinic acid, potassium chloroplatinite, sodium chloroplatinite or platinum chloride; and the inorganic auxiliary reagent is sodium citrate solution or potassium citrate solution.

[0013] As an improvement, the rare earth metal salt described in step (1) is a rare earth metal chloride, a rare earth metal nitrate or a rare earth metal sulfate.

[0014] A further improvement is that the rare earth metal of the rare earth metal salt in step (1) is lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium or terbium.

[0015] As an improvement, the carbon black in step (1) is Vulcan XC72, Ketjen Black EC300J, or Ketjen Black EC600JD.

[0016] As an improvement, the molar ratio of platinum salt to transition metal salt in the platinum salt solution and the rare earth metal salt solution in step (1) is 1:0.3-1.

[0017] As an improvement, the mass ratio of platinum salt to carbon black in the platinum salt solution described in step (1) is 1:1-18.

[0018] As an improvement, the operation of Joule thermal shock in step (2) is: placing the carbon black loaded by the precursor in a graphite boat carrier and placing it in a Joule thermal device, setting the voltage to 10-30V, the current to 250-300A, the Joule heating time to 15-60 seconds, and the Joule heating temperature range to 1300°C-1700°C depending on the size of the shock current.

[0019] The platinum-rare earth-based intermetallic compound prepared by the above method is of Pt2Ln type, has a uniform size of 8 nm, and has many active sites.

[0020] The platinum-rare earth-based intermetallic compound prepared by the above method is used as a catalyst in the cathode hydrogen evolution reaction of an anion exchange membrane water electrolysis system.

[0021] Beneficial effects:

[0022] Compared with the traditional tube furnace thermal annealing method or the reported physical metallurgy method, arc melting method, and magnetron sputtering method, the platinum-rare earth-based intermetallic compound and its rapid high-throughput preparation method and application of the present invention have the following advantages:

[0023] 1. The present invention proposes for the first time to use the Joule heating method to prepare platinum-rare earth-based intermetallic compounds. The preparation method is simple and fast, and a single preparation only takes 15 seconds. It can prepare platinum-rare earth-based intermetallic compounds in a high-throughput manner in a short time and realize gram-level production of catalysts.

[0024] 2. The platinum-rare earth-based intermetallic compound prepared by the method of the present invention is evenly distributed on the surface of carbon black and has a uniform size, with a diameter of about 8 nm. It has more active sites and a stable structure. It exhibits excellent electrocatalytic activity for the cathode hydrogen evolution reaction of the anion exchange membrane water electrolysis system and has a very broad prospect for energy application. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 (a) is a transmission electron microscopy (TEM) image of carbon-supported Pt2Tb intermetallic compound nanoparticles prepared in Example 1;

[0026] Figure 1 (b) is a particle size distribution diagram of carbon-supported Pt2Tb intermetallic compound nanoparticles prepared in Example 1;

[0027] Figure 2 The X-ray diffraction (XRD) pattern of the carbon-supported Pt2Tb intermetallic compound nanoparticles prepared in Example 1;

[0028] Figure 3 The carbon-supported Pt2Tb intermetallic compound nanoparticles prepared in Example 1 were heated to 1 mol L -1 HER polarization curve in KOH;

[0029] Figure 4 The carbon-supported Pt2Tb intermetallic compound nanoparticles prepared in Example 1 were used as cathode catalysts in an anion exchange membrane water electrolysis system at a temperature of 80°C and a current density of 1 A cm -2 Chronopotentiometry curves. DETAILED DESCRIPTION

[0030] The technical solution of the present invention is further described in detail below through specific embodiments. However, it is necessary to point out that the following embodiments are only used to describe the content of the invention and do not constitute a limitation on the protection scope of the present invention.

[0031] Example 1

[0032] 1.5 ml 0.05 mol L -1 chloroplatinic acid solution, 0.75ml 0.05mol L -1 Terbium chloride solution and 3.5 ml 0.05 mol L -1 The sodium citrate solution was ultrasonically mixed, 0.06 g of Vulcan XC72 was added thereto, and the mixture was further ultrasonically mixed to obtain a mixed solution, and the obtained mixed solution was freeze-dried. An appropriate amount of the dried powder was placed in two graphite boats and placed in a Joule heating device, the voltage was set to 12 V, the current was 300 A, the Joule heating time was 15 s, and the thermal shock temperature was 1500 ° C under this condition. After the Joule heating was completed, the sample was taken out, washed and dried to obtain carbon-supported Pt2Tb intermetallic compound nanoparticles.

[0033] Example 2

[0034] The difference from Example 1 is that chloroplatinic acid is replaced by potassium chloroplatinite, and the rest of the content is consistent with Example 1.

[0035] Example 3

[0036] The difference from Example 1 is that chloroplatinic acid is replaced by sodium chloroplatinite, and the rest of the content is consistent with Example 1.

[0037] Example 4

[0038] The difference from Example 1 is that chloroplatinic acid is replaced by platinum chloride, and the rest of the content is consistent with Example 1.

[0039] Example 5

[0040] The difference from Example 1 is that terbium chloride is replaced by lanthanum chloride, and the corresponding product is Pt2La. The rest of the content is consistent with Example 1.

[0041] Example 6

[0042] The difference from Example 1 is that terbium chloride is replaced by cerium chloride, and the corresponding product is Pt2Ce. The rest of the content is consistent with Example 1.

[0043] Example 7

[0044] The difference from Example 1 is that terbium chloride is replaced by praseodymium chloride, and the corresponding product is Pt2Pr. The rest of the content is consistent with Example 1.

[0045] Example 8

[0046] The difference from Example 1 is that terbium chloride is replaced by neodymium chloride, and the corresponding product is Pt2Nd. The rest of the content is consistent with Example 1.

[0047] Example 9

[0048] The difference from Example 1 is that terbium chloride is replaced by samarium chloride, and the corresponding product is Pt2Sm. The rest of the content is consistent with Example 1.

[0049] Example 10

[0050] The difference from Example 1 is that terbium chloride is replaced by europium chloride, and the corresponding product is Pt2Eu. The rest of the content is consistent with Example 1.

[0051] Embodiment 11

[0052] The difference from Example 1 is that terbium chloride is replaced by gadolinium chloride, and the corresponding product is Pt2Gd. The rest of the content is consistent with Example 1.

[0053] Example 12

[0054] The difference from Example 1 is that terbium chloride is replaced by terbium nitrate, and the corresponding product is Pt2Tb. The rest of the content is consistent with Example 1.

[0055] Example 13

[0056] The difference from Example 1 is that terbium chloride is replaced by terbium sulfate, and the corresponding product is Pt2Tb. The rest of the content is consistent with Example 1.

[0057] Embodiment 14

[0058] The difference from Example 1 is that Vulcan XC72 is replaced by Ketjen Black EC300J, and the rest of the contents are consistent with Example 1.

[0059] Embodiment 15

[0060] The difference from Example 1 is that Vulcan XC72 is replaced by Ketjen Black EC600JD, and the rest of the contents are consistent with Example 1.

[0061] Example 16

[0062] The difference from Example 1 is that the sodium citrate solution is replaced by a potassium citrate solution, and the rest of the contents are consistent with Example 1.

[0063] Embodiment 17

[0064] The difference from Example 1 is that 0.75 ml of 0.05 mol L -1 Terbium chloride was replaced with 0.45 ml 0.05 mol L -1 Terbium chloride, and the rest of the contents are consistent with those in Example 1.

[0065] Embodiment 18

[0066] The difference from Example 1 is that 0.75 ml of 0.05 mol L -1 Terbium chloride was replaced with 1.5 ml 0.05 mol L -1 Terbium chloride, and the rest of the contents are consistent with those in Example 1.

[0067] Embodiment 19

[0068] The difference from Example 1 is that 0.06 g of Vulcan XC72 is replaced by 0.04 g of Vulcan XC72, and the rest of the content is consistent with Example 1.

[0069] Embodiment 20

[0070] The difference from Example 1 is that 0.06 g of Vulcan XC72 is replaced by 0.54 g of Vulcan XC72, and the rest of the content is consistent with Example 1.

[0071] Embodiment 21

[0072] The difference from Example 1 is that the voltage of 12V and the current of 300A are replaced by the voltage of 10V and the current of 250A. Under this condition, the thermal shock temperature is 1300°C. The rest of the contents are consistent with Example 1.

[0073] Embodiment 22

[0074] The difference from Example 1 is that the voltage of 12V and the current of 300A are replaced by the voltage of 30V and the current of 300A. Under this condition, the thermal shock temperature is 1700°C. The rest of the contents are consistent with Example 1.

[0075] Embodiment 23

[0076] The difference from Example 1 is that the Joule heating time of 15 s is replaced by the Joule heating time of 60 s, and the rest of the contents are consistent with Example 1.

[0077] Comparative Example 1

[0078] On the basis of Example 1, no rare earth terbium source was added and other conditions remained unchanged.

[0079] Performance Testing

[0080] (1) The carbon-supported Pt3Mn intermetallic compound nanoparticles prepared in Example 1 were physically characterized using a transmission electron microscope (TEM), and the corresponding particle size distribution diagram was as follows: Figure 1 shown.

[0081] Depend on Figure 1 It can be seen that the Pt2Tb intermetallic compound prepared according to the preparation method of the present invention is evenly distributed on the surface of carbon black and has a uniform size, with a diameter of about 8 nm.

[0082] (2) The carbon-supported Pt2Tb intermetallic compound nanoparticles prepared in Example 1 were subjected to an X-ray diffraction test to obtain an XRD spectrum. The results are as follows: Figure 2 shown.

[0083] Depend on Figure 2 It can be seen that the diffraction peak position of the Pt2Tb intermetallic compound nanoparticles completely coincides with the Pt2Tb intermetallic compound standard card (PDF#97-010-5807), proving the formation of the intermetallic phase.

[0084] (3) Commercial Pt / C (Johnson Matthey, USA) was selected as the reference catalyst and 1 mol L -1 Hydrogen evolution (HER) polarization curves were tested in KOH for the carbon-supported Pt2Tb intermetallic compound nanoparticles prepared in Example 1, the comparative example, and commercial Pt / C. The test was performed on a CHI 760E electrochemical workstation using a three-electrode system with a test voltage range of -0.4V-0V and a scan rate of 5mV / s. All measured potentials were converted to reversible hydrogen electrodes.

[0085] Depend on Figure 3 It can be seen that the Pt2Tb intermetallic compound electrocatalyst prepared in Example 1 has a current density of 10 mA cm -2 The overpotential at 14 mV is only 14 mV, which is better than commercial Pt / C (37 mV) and comparative catalyst (47 mV). It can be seen that the HER activity of the Pt2Tb catalyst prepared in Example 1 in alkaline electrolyte is better than that of commercial Pt / C, which is mainly attributed to the introduction of the rare earth element Tb to form a Pt2Ln type intermetallic compound with Pt, which significantly optimizes the electronic structure of Pt and improves its catalytic performance.

[0086] (4) The carbon-supported Pt2Tb intermetallic compound nanoparticles prepared in Example 1 were used as the cathode catalyst of the anion exchange membrane water electrolysis system, and the anode was a commercial NiFe-LDH catalyst. The assembled water electrolysis system was operated at 80°C.

[0087] Depend on Figure 4 It can be seen that at 1A cm -2 At a current density of , the operating potential of the anion exchange membrane water electrolysis system was about 1.85 V, and it operated stably for 100 h, demonstrating good activity and stability.

[0088] In summary, the present invention proposes for the first time to use Joule heating to prepare platinum-rare earth-based (Pt2Ln type) intermetallic compounds. The preparation method is simple and fast, and can prepare platinum-rare earth-based intermetallic compounds with high throughput in a short time. The prepared intermetallic compound nanoparticles are uniformly loaded on the surface of carbon black, with a uniform size of about 8 nm, and exhibit excellent electrocatalytic activity for the cathode hydrogen evolution reaction of anion exchange membrane water electrolysis. In addition, this method effectively solves the problem of difficulty in preparing platinum-rare earth-based intermetallic compound nanoparticles, and has good market prospects.

[0089] The present invention and its embodiments are described schematically above, and the description is not restrictive. The drawings show only one embodiment of the present invention, and the actual structure is not limited thereto. Therefore, if a person skilled in the art is inspired by it and designs a structural method and an embodiment similar to the technical solution without creativity without departing from the purpose of the invention, they shall all fall within the protection scope of the present invention.

Claims

1. A rapid high-throughput preparation method for a platinum-rare earth-based intermetallic compound, characterized in that: The following steps are involved: (1) Preparation of carbon black loaded with metal salt precursor After uniformly mixing the platinum salt solution, the rare earth metal salt solution and the inorganic auxiliary reagent by ultrasonication, carbon black is added and ultrasonication is continued to obtain a metal salt precursor mixed solution; (2) Preparation of platinum-rare earth-based intermetallic compounds by short-term continuous Joule heating The metal salt precursor mixture is freeze-dried, and the freeze-dried powder is Joule heated. After the powder is heated, it is taken out, washed and dried to obtain a platinum-rare earth-based intermetallic compound.

2. The rapid high-throughput preparation method of platinum-rare earth-based intermetallic compounds according to claim 1, characterized in that: The platinum salt described in step (1) is chloroplatinic acid, potassium chloroplatinite, sodium chloroplatinite or platinum chloride; and the inorganic auxiliary reagent is sodium citrate solution or potassium citrate solution.

3. The rapid high-throughput preparation method of platinum-rare earth-based intermetallic compounds according to claim 1, characterized in that: The rare earth metal salt described in step (1) is a rare earth metal chloride, a rare earth metal nitrate or a rare earth metal sulfate.

4. The rapid high-throughput preparation method of platinum-rare earth-based intermetallic compounds according to claim 3, characterized in that: The rare earth metal of the rare earth metal salt in step (1) is lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium or terbium.

5. The rapid high-throughput preparation method of platinum-rare earth-based intermetallic compounds according to claim 3, characterized in that: The carbon black described in step (1) is Vulcan XC72, Ketjen Black EC300J, or Ketjen Black EC600JD.

6. The rapid high-throughput preparation method of platinum-rare earth-based intermetallic compounds according to claim 3, characterized in that: The molar ratio of the platinum salt to the transition metal salt in the platinum salt solution and the rare earth metal salt solution in step (1) is 1:0.3-1.

7. The rapid high-throughput preparation method of platinum-rare earth-based intermetallic compounds according to claim 3, characterized in that: The mass ratio of platinum salt to carbon black in the platinum salt solution described in step (1) is 1:1-18.

8. The rapid high-throughput preparation method of platinum-rare earth-based intermetallic compounds according to claim 3, characterized in that: The operation of Joule thermal shock in step (2) is as follows: the carbon black loaded by the precursor is placed in a graphite boat carrier and placed in a Joule thermal device, the voltage is set to 10-30V, the current is set to 250-300A, the Joule heating time is set to 15-60 seconds, and the Joule heating temperature range can reach 1300°C-1700°C depending on the size of the shock current.

9. The platinum-rare earth-based intermetallic compound prepared by the method according to claim 1, characterized in that: The platinum-rare earth-based intermetallic compound is of Pt2Ln type, has a uniform size of 8 nm, and has many active sites.

10. Use of the platinum-rare earth-based intermetallic compound prepared by the method according to claim 1 as a catalyst in the cathode hydrogen evolution reaction of an anion exchange membrane water electrolysis system.

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