Hydrogen evolution catalyst and water electrolysis hydrogen production cathode based on amorphous high-entropy hydroxide loaded platinum clusters synthesized by water thermal method

Abstract

The application provides a hydrogen evolution catalyst based on amorphous high-entropy hydroxide loaded platinum cluster synthesized by water thermal method and a preparation method thereof, and belongs to the technical field of electrocatalytic hydrogen production. The catalyst takes foamed nickel-molybdenum as a substrate, is immersed in a nitrate solution containing cobalt, iron and cerium, and is subjected to a hydrothermal reaction while an external uniform magnetic field is applied to synthesize amorphous high-entropy hydroxide, then the high-entropy hydroxide is immersed in a potassium chloroplatinate solution, platinum clusters are loaded on the high-entropy hydroxide, and a Pt-O-M (M=Co, Fe, Ce, Ni, Mo) bridge bond is formed. The obtained electrocatalyst has high hydrogen evolution activity, long-term stability under long-term alkaline high current density, and low platinum loading of the catalyst, so it has low cost and great application potential.

Description

Technical Field

[0001] This invention relates to a hydrogen evolution catalyst based on magnetic field hydrothermal synthesis of amorphous high-entropy hydroxide-supported platinum clusters and its preparation method, belonging to the technical field of hydrogen production catalysts by water electrolysis. Background Technology

[0002] Hydrogen production through water electrolysis is crucial for achieving a clean energy system. As the core of water electrolysis technology, the performance of the electrocatalyst directly determines the energy conversion efficiency and cost. Currently, high-performance electrocatalysts mainly rely on precious metal materials such as platinum (Pt), iridium (Ir), and ruthenium (Ru). While these materials possess excellent intrinsic activity, their high precious metal content, coupled with the scarcity and high price of precious metals globally, significantly restricts the large-scale commercial application of related technologies. Developing new hydrogen evolution electrocatalysts can not only optimize performance but also reduce costs and increase efficiency.

[0003] Currently, commercially available catalysts mainly consist of platinum-carbon and ruthenium dioxide. However, their high precious metal content leads to resource and cost issues, requiring the creation of an ink containing a binder before coating onto a substrate. While their intrinsic properties are acceptable, they suffer from poor stability under industrial conditions and are prone to catalyst detachment. Both theoretical calculations and experiments show that Pt's hydrogen adsorption free energy is close to zero, placing it at the peak position in the hydrogen evolution reaction volcano diagram and exhibiting near-optimal intrinsic catalytic activity. Therefore, designing catalysts with low platinum content and high stability remains a significant challenge.

[0004] In 2020, Zhang Zhen et al. proposed a platinum-based catalyst and its preparation method and application [CN111841600B]. This invention application provides a platinum-based catalyst. Its characteristics include a nitrogen-containing carbon support and platinum atoms supported on the nitrogen-containing carbon support. The nitrogen-containing carbon support has good electrical conductivity, and by doping with a high content of nitrogen, it is beneficial for the adsorption, coordination, and anchoring of platinum atoms, allowing the platinum atoms to be uniformly distributed in a single-atom state on the nitrogen-containing carbon support. This belongs to a supported catalyst.

[0005] The catalyst support used in the above work is a carbon-containing material. Under the action of cathode polarization, the permeation of adsorbed hydrogen atoms leads to the hydrogenation of the carbon skeleton and sp. 2 Bond breakage leads to structural fragility, and this negative effect is exacerbated under industrial conditions. Therefore, the prepared nitrogen-containing carbon-supported catalysts have certain limitations.

[0006] In 2024, Li Qi et al. proposed a platinum-based self-supporting membrane catalyst, its preparation method, and its application in electrocatalytic hydrogen evolution [CN119101935A]. This invention application provides a platinum-based self-supporting membrane catalyst. Its key feature is the deposition of platinum nanoparticles onto the surface of a CC@MOF crystal film using a wet reduction method, followed by high-temperature heat treatment to form a CC@MOF / Pt platinum-based self-supporting membrane catalyst. This catalyst possesses abundant active sites, high specific surface area, and high stability.

[0007] From the current research status and progress of electrocatalysts, self-supported catalysts possess high stability due to their noble metal supports, and the active centers are more firmly bonded to the substrate in situ. They also eliminate the need for binders required by traditional powder catalysts, avoiding the additional resistance, active site coverage, and binder degradation problems introduced by these materials. These advantages have made these catalysts increasingly important. Developing a high-performance electrocatalyst with high active area and low noble metal loading is of great significance. Summary of the Invention

[0008] To address the aforementioned problems, the present invention aims to provide a hydrogen evolution catalyst based on magnetic field hydrothermal synthesis of amorphous high-entropy hydroxide-supported platinum clusters and its preparation method.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] In a first aspect, the present invention provides a hydrogen evolution catalyst, comprising: Porous metal substrate; An amorphous high-entropy hydroxide layer loaded on the surface of the porous metal substrate; And platinum clusters loaded on the amorphous high-entropy hydroxide layer; The platinum clusters form bridging bonds (e.g., Pt-OM bonds, where M is a transition metal) with at least one metal element in the amorphous high-entropy hydroxide layer.

[0011] Preferably, the microstructure of the amorphous high-entropy hydroxide layer is a nano-petal sphere structure, and the nano-petal sphere structure uniformly covers the surface of the porous metal substrate.

[0012] Preferably, the porous metal substrate is a foamed nickel-molybdenum substrate.

[0013] Preferably, the amorphous high-entropy hydroxide layer contains at least three metallic elements selected from cobalt, iron, and cerium.

[0014] Secondly, the present invention provides a method for preparing the above-mentioned hydrogen evolution catalyst, comprising the following steps: (1) A porous metal substrate is immersed in a mixed solution containing at least three transition metal salts and subjected to a hydrothermal reaction under an external magnetic field to obtain a precatalyst; the precatalyst is a porous metal substrate with amorphous high-entropy hydroxides loaded on its surface. (2) The pre-catalyst obtained in step (1) is impregnated in a platinum-containing solution and subjected to a loading reaction under an external magnetic field to obtain the hydrogen evolution catalyst.

[0015] In some preferred embodiments, in step (1), the transition metal salt is selected from at least three of cobalt, iron, cerium, nickel, and molybdenum salts. Preferably, the mixed solution also contains a complexing agent, such as disodium EDTA, the concentration of which matches the total concentration of the transition metal salt.

[0016] In some preferred embodiments, in step (1), the conditions for the hydrothermal reaction include: a reaction temperature of 80-180℃ and a reaction time of 4-24 hours; and the strength of the external magnetic field is 0.05-0.5T.

[0017] In some preferred embodiments, in step (2), the platinum-containing solution is a potassium chloroplatinate solution or a chloroplatinic acid solution; the concentration of the platinum-containing solution is 1-20 mmol / L; and the loading reaction time is 0.5-5 hours.

[0018] In some preferred embodiments, in step (2), the strength of the external magnetic field is 0.05-0.5T and the direction is perpendicular to the surface of the precatalyst.

[0019] In some preferred embodiments, the method further includes a pretreatment step of the porous metal substrate prior to step (1), the pretreatment comprising ultrasonic cleaning in an acid solution, deionized water and an organic solvent in sequence.

[0020] In some preferred embodiments, the external magnetic field in the hydrothermal reaction and / or the load reaction is a constant magnetic field or an alternating magnetic field.

[0021] In some preferred embodiments, the second aspect includes the following steps: (1) Cut a 2cm piece 2cm Commercially available nickel-molybdenum foam with a specification of 0.1 cm and a ppi of 110 was ultrasonically cleaned for 10 minutes each in 1.0 mol / L dilute hydrochloric acid, deionized water, and ethanol.

[0022] (2) Prepare solutions of cobalt nitrate, ferric nitrate, and cerium nitrate with the same concentrations of 0.01 mol / L to 0.05 mol / L, mix them with a solution of disodium EDTA salt with concentrations of 0.03 mol / L to 0.15 mol / L, and place the cleaned and dried nickel-molybdenum foam in the mixture. The mixture is then subjected to a hydrothermal reaction at 120℃ for 8 hours, while a constant magnetic field of 0.15T is applied to both the top and bottom surfaces of the hydrothermal chamber. After the reaction is complete, cool to room temperature, remove the mixture, wash it several times with deionized water, and dry it in a vacuum oven to obtain an amorphous high-entropy alloy precatalyst.

[0023] (3) Further, the pre-catalyst treated in step (2) is horizontally immersed in a 10 mmol / L potassium chloroplatinate solution, while a static magnetic field of 0.15T is preset externally. After immersion for 1 hour, it is taken out, washed with deionized water and dried to obtain a hydrogen evolution catalyst with amorphous high-entropy hydroxide-supported platinum clusters.

[0024] Thirdly, the present invention provides the application of the above-mentioned hydrogen evolution catalyst or the hydrogen evolution catalyst prepared by the above-mentioned preparation method as a cathode material in water electrolysis for hydrogen production.

[0025] Fourthly, the present invention provides a hydrogen production cathode for water electrolysis, which comprises the above-mentioned hydrogen evolution catalyst.

[0026] This invention uses nickel-molybdenum foam as the molybdenum source, nickel source, and self-supporting substrate. Through a hydrothermal reaction, cobalt, cerium, and iron atoms partially replace the nickel and molybdenum atoms in the substrate. The surface layer consists of hydroxides of each component, forming an amorphous layer, thus obtaining a high-entropy hydroxide precatalyst with a uniformly grown nano-petal sphere microstructure. The amorphous layer on the surface has abundant reducing sites; therefore, in the second step, the precatalyst is impregnated in a potassium chloroplatinate solution, where platinum atoms are loaded onto the amorphous layer in clusters. The hydrothermal reaction and the external magnetic field applied during the subsequent platinum-containing solution impregnation process further enhance the uniformity of the nanostructure arrangement.

[0027] Beneficial effects: The hydrogen evolution catalyst prepared by this invention, consisting of amorphous high-entropy hydroxide-supported platinum clusters, exhibits excellent performance and high reproducibility. The platinum loading is lower than that of commercial platinum-carbon catalysts, resulting in lower cost.

[0028] Compared with the prior art, the present invention has the following advantages: (1) This invention fundamentally optimizes the problems of carrier corrosion and active center instability. Existing self-supporting technologies still rely on carbon-based carriers, which inevitably undergo electrochemical corrosion under harsh working conditions, leading to structural collapse and the shedding of active components. This invention abandons unstable carbon materials and is based on amorphous high-entropy alloys. Due to their long-range disorder and rich dangling bonds, they can provide a multi-site, multi-angle chemical anchoring for platinum atom clusters.

[0029] (2) In the process flow of this invention, an external constant magnetic field is set. The external magnetic field during the hydrothermal reaction can guide the metal ions in a directional manner, thereby making the doping more uniform. The external magnetic field during the immersion in potassium chloroplatinate solution can suppress the random aggregation of chloroplatinate ions. The above features can optimize the distribution uniformity of the nanoflower structure on the substrate surface to the greatest extent, so that the active sites are fully exposed.

[0030] (3) As a platinum-containing hydrogen evolution catalyst, this invention also shows performance in terms of platinum loading, with a platinum mass fraction of 2.08%, which significantly reduces costs. Attached Figure Description

[0031] Figure 1 The Pt / CoNiMoCeFe- in Example 1 Scanning electron microscope image.

[0032] Figure 2 The Pt / CoNiMoCeFe- in Example 1 Transmission electron microscopy images: A is a high-resolution image of the nanopetal spheres; B is a detailed image.

[0033] Figure 3 The Pt / CoNiMoCeFe- in Example 1 X-ray photoelectron spectroscopy (XPS) of Pt 4f.

[0034] Figure 4 CoNiMoCeFe- in Example 1 Energy dispersive X-ray spectra (EDX) of cobalt, cerium, and iron, where A represents Co, B represents Ce, and C represents Fe.

[0035] Figure 5 For example, Pt / CoNiMoCeFe- CoNiMoCeFe- X-ray photoelectron spectroscopy of O 1s.

[0036] Figure 6 The image shows a scanning electron microscope (SEM) image of Pt / CoNiMoCeFe in Comparative Example 1.

[0037] Figure 7 For the Pt / CoNiMoCeFe- in Comparative Example 3 Scanning electron microscope image.

[0038] Figure 8 The Pt / CoNiMoCeFe- in Example 1 Linear sweep voltammetry (LSV) curves of Pt / CoNiMoCeFe catalyst in Comparative Example 1 and Pt-C catalyst in Comparative Example 2.

[0039] Figure 9 The Pt / CoNiMoCeFe- in Example 1 Tafel curves of the Pt / CoNiMoCeFe catalyst in Comparative Example 1 and the Pt-C catalyst in Comparative Example 2.

[0040] Figure 10 The Pt / CoNiMoCeFe- in Example 1 Electrochemical impedance spectroscopy of Pt / CoNiMoCeFe catalyst in Comparative Example 1 and Pt-C catalyst in Comparative Example 2.

[0041] Figure 11 The Pt / CoNiMoCeFe- in Example 1 Multi-step current test diagram.

[0042] Figure 12 The Pt / CoNiMoCeFe- in Example 1 The Pt-C catalyst of Comparative Example 2 was used at 100 mA cm⁻¹ -2 Stability test results at current density. Detailed Implementation

[0043] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. The described embodiments are only some embodiments of the present invention, and not all embodiments. Unless otherwise specified, the manufacturers of reagents and consumables refer to conventional products that can be purchased on the market.

[0044] Example 1 A hydrogen evolution catalyst based on magnetic field hydrothermal synthesis of amorphous high-entropy hydroxide-supported platinum clusters and its preparation method, comprising the following steps: Substrate pretreatment: Cut commercially available nickel-molybdenum foam (ppi=110) of 2 cm × 2 cm × 0.1 cm, and ultrasonically clean it for 10 minutes each in 1.0 mol / L dilute hydrochloric acid, deionized water, and anhydrous ethanol, and then vacuum dry it for later use.

[0045] Magnetic field-assisted hydrothermal synthesis of precatalyst: Prepare 20 mL each of 0.02 mol / L solutions of cobalt nitrate, ferric nitrate, and cerium nitrate, and mix them thoroughly with 20 mL of 0.06 mol / L disodium EDTA solution. Transfer the mixture to a 100 mL hydrothermal reactor liner and place pretreated nickel-molybdenum foam inside. Place the hydrothermal reactor in a custom-designed hydrothermal chamber, and apply a constant magnetic field of 0.2 T to both the top and bottom surfaces of the chamber. Perform the hydrothermal reaction at 120℃ for 8 hours. After the reaction, allow it to cool naturally to room temperature, remove the product, wash repeatedly with deionized water, and vacuum dry at 60℃ to obtain an amorphous high-entropy hydroxide precatalyst, denoted as CoNiMoCeFe- ( (Indicates magnetic field assistance).

[0046] Magnetic field-assisted impregnation of supported platinum clusters: A 10 mmol / L potassium chloroplatinate solution was prepared. The pre-catalyst was horizontally immersed in this solution while a constant magnetic field of 0.1 T was applied perpendicular to the liquid surface. After impregnation at room temperature for 1 hour, the catalyst was removed, washed with deionized water, and dried under vacuum at 60 °C to obtain the final catalyst, denoted as Pt / CoNiMoCeFe- .

[0047] Scanning electron microscope images of Pt / CoNiMoCeFe- The microstructure of nano-petal spheres, such as Figure 1 As shown.

[0048] Pt / CoNiMoCeFe- (transmission electron microscopy) The figure and the X-ray photoelectron spectroscopy (XPS) of Pt element show that Pt was successfully loaded onto an amorphous substrate, such as Figure 2 (It can be seen that in the image at higher magnification, the brighter areas are amorphous layers, and the darker areas are platinum cluster loads.) Figure 3 As shown.

[0049] CoNiMoCeFe- The EDX line scans show that Co, Ce, and Fe have been successfully doped into nickel-molybdenum hydroxide, as shown in the image. Figure 4 As shown; XPS peak fitting was performed on the O element in the samples before and after Pt loading, by Figure 5 It can be seen that the introduction of Pt caused a significant shift in the M-OH bond. Combined with the results of TEM and EDX, it can be determined that this is because Pt atoms formed Pt-O-M1 chemical bonds with transition metal atoms in the amorphous layer.

[0050] Comparative Example 1 The cleaned and dried nickel-molybdenum foam was placed in a mixed solution of cobalt nitrate, ferric nitrate, cerium nitrate, and disodium EDTA and hydrothermally reacted at 120°C for 8 hours. After the reaction, it was cooled to room temperature, washed several times with deionized water, and dried in a vacuum oven to obtain a pre-catalyst prepared without magnetic field control. The pre-catalyst was then horizontally immersed in a 10 mmol / L potassium chloroplatinate solution for 1 hour, washed with deionized water, and dried to obtain the hydrogen evolution catalyst Pt / CoNiMoCeFe prepared without magnetic field control.

[0051] Scanning electron microscopy (SEM) images of the Pt / CoNiMoCeFe nanopetal spheres show that, without an external magnetic field, the surface irregularity increases, such as... Figure 6 As shown.

[0052] Comparative Example 2 The cleaned and dried nickel-molybdenum foam was placed in a mixed solution of cobalt nitrate, ferric nitrate, cerium nitrate, and disodium EDTA and hydrothermally reacted at 120°C for 8 hours, while a constant magnetic field of 2T was applied to both the top and bottom surfaces of the hydrothermal chamber. After the reaction, the catalyst was cooled to room temperature, washed several times with deionized water, and dried in a vacuum oven to obtain a pre-catalyst prepared under high magnetic field strength control. The pre-catalyst was then horizontally immersed in a 10 mmol / L potassium chloroplatinate solution under a constant magnetic field of 2T for 1 hour, then removed, washed with deionized water, and dried to obtain the hydrogen evolution catalyst Pt / CoNiMoCeFe- prepared under high magnetic field strength control. .

[0053] Scanning electron microscope images of Pt / CoNiMoCeFe- The microstructure indicates that under excessively high magnetic field conditions, the surface morphology exhibits excessive aggregation, which has the opposite effect on exposing active sites. Figure 7 As shown.

[0054] Comparative Example 3 5 mg of 20% commercial platinum-carbon catalyst and 1 mg of commercial Super-P powder were mixed in 480 μL of ethanol and 20 μL of Nafion (5 wt%). After sonication for 20 minutes, 200 μL of the uniformly dispersed catalyst ink was drop-coated onto nickel foam. 1cm 2 The Pt-C catalyst is obtained by drying the Pt-C catalyst in the region where it is placed and then placed in an oven.

[0055] Test Example 1 A three-electrode testing system was constructed, with a 1 mol / L KOH solution as the electrolyte. The Pt / CoNiMoCeFe- from Example 1 was used. The Pt / CoNiMoCeFe catalyst in Comparative Example 1 and the Pt-C catalyst in Comparative Example 2 were used as working electrodes, the mercury / mercury oxide electrode was used as the reference electrode, and the graphite rod was used as the counter electrode.

[0056] like Figure 8 The figure shows the linear sweep voltammetry (LSV) curves of different samples, showing that Pt / CoNiMoCeFe- It exhibits the best HER catalytic performance.

[0057] like Figure 9 The figure shows the Tafel curves for different samples. From the figure, it can be seen that Pt / CoNiMoCeFe- It has the smallest Tafel slope, indicating that it has the fastest HER reaction kinetics.

[0058] like Figure 10 The figure shows the electrochemical impedance spectroscopy (EIS) spectra of different samples. From the figure, it can be seen that Pt / CoNiMoCeFe- It has a significantly small charge transfer impedance.

[0059] Test Example 2 Using Pt / CoNiMoCeFe- in Example 1 As a test subject, in order to verify its potential for industrial application, a series of stability tests were carried out on it by building a three-electrode system, including multi-step current test and constant current long-term stability test.

[0060] like Figure 11 The image shows Pt / CoNiMoCeFe- The I-STEP test curves show current densities of 10 mA cm⁻¹. -2 50 mA cm -2 100 mA cm -2 300 mA cm -2 500 mA cm -2 The duration of each current density step is 10 hours.

[0061] like Figure 12 The image shows Pt / CoNiMoCeFe- Long-term stability tests were conducted at a constant current density of 100 mA cm⁻¹. -2 As shown in the figure, no significant performance degradation was observed after more than 100 hours of testing.

[0062] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A hydrogen evolution catalyst based on magnetic field hydrothermal synthesis of amorphous high-entropy hydroxide-supported platinum clusters, characterized in that, The hydrogen evolution catalyst includes: Porous metal substrate; An amorphous high-entropy hydroxide layer loaded on the surface of the porous metal substrate; And platinum clusters loaded on the amorphous high-entropy hydroxide layer; The platinum clusters form bridging bonds with at least one metal element in the amorphous high-entropy hydroxide layer.

2. The hydrogen evolution catalyst according to claim 1, characterized in that, The microstructure of the amorphous high-entropy hydroxide layer is a nano-petal sphere structure, and the nano-petal sphere structure uniformly covers the surface of the porous metal substrate.

3. The hydrogen evolution catalyst according to claim 1 or 2, characterized in that, The porous metal substrate is a foamed nickel-molybdenum alloy; the amorphous high-entropy hydroxide layer contains at least three metal elements selected from cobalt, iron, and cerium.

4. A method for preparing a hydrogen evolution catalyst according to any one of claims 1-3, characterized in that, Includes the following steps: (1) A porous metal substrate is immersed in a mixed solution containing at least three transition metal salts and subjected to a hydrothermal reaction under an external magnetic field to obtain a precatalyst; the precatalyst is a porous metal substrate with amorphous high-entropy hydroxides loaded on its surface. (2) The pre-catalyst obtained in step (1) is impregnated in a platinum-containing solution and subjected to a loading reaction under an external magnetic field to obtain the hydrogen evolution catalyst.

5. The preparation method according to claim 4, characterized in that, In step (1), the transition metal salt is selected from at least three of cobalt salt, iron salt, cerium salt, nickel salt, and molybdenum salt; preferably, the mixed solution also contains a complexing agent; The conditions for the hydrothermal reaction include: a reaction temperature of 80-180℃ and a reaction time of 4-24 hours; the strength of the external magnetic field is 0.05-0.5T.

6. The preparation method according to claim 4, characterized in that, In step (2), the platinum-containing solution is a potassium chloroplatinate solution or a chloroplatinic acid solution; the concentration of the platinum-containing solution is 1-20 mmol / L; the loading reaction time is 0.5-5 hours; the strength of the external magnetic field is 0.05-0.5T, and the direction is perpendicular to the surface of the pre-catalyst.

7. The preparation method according to claim 4, characterized in that, It also includes a step of pretreating the porous metal substrate before step (1), the pretreatment including ultrasonic cleaning in an acid solution, deionized water and an organic solvent in sequence.

8. The preparation method according to claim 4, characterized in that, The external magnetic field in the hydrothermal reaction and / or the load reaction is a constant magnetic field or an alternating magnetic field.

9. The application of the hydrogen evolution catalyst according to any one of claims 1-3 or the hydrogen evolution catalyst prepared by the preparation method according to any one of claims 4-8 as a cathode material in water electrolysis for hydrogen production.

10. A cathode for hydrogen production by water electrolysis, characterized in that, The hydrogen evolution catalyst comprising any one of claims 1-3 or the hydrogen evolution catalyst prepared by any one of claims 4-8.

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