Multiphase platinum-loaded nickel-vanadium layered double-metal hydroxide electrocatalyst as well as preparation method and application of multiphase platinum-loaded nickel-vanadium layered double-metal hydroxide electrocatalyst

Abstract

The invention relates to a multi-phase platinum-loaded nickel-vanadium layered double hydroxide electrocatalyst as well as a preparation method and application thereof. The preparation method comprises the following steps: dissolving nickel salt and vanadium salt in deionized water to obtain a nickel-vanadium salt mixed solution; ammonium fluoride and urea are added into the nickel vanadium salt mixed solution to be adjusted; mixing the adjusted mixed solution with the pretreated foamed nickel, and carrying out hydrothermal reaction to obtain nickel-vanadium layered double hydroxides; soaking the self-supporting precursor in a Pt-containing saline solution which is subjected to oxygen removal treatment by introducing inert gas in advance; and placing the multiphase platinum-loaded intermediate in an inert atmosphere, and calcining to obtain the multiphase platinum-loaded nickel-vanadium layered double-metal hydroxide electrocatalyst. According to the prepared catalyst, the foamed nickel serves as a self-supporting carrier and has a high specific surface area and high-density active sites, and the hydrogen evolution activity and long-term stability of hydrogen production through alkaline electrolysis of water are remarkably improved through the synergistic effect of multiphase Pt and a substrate.

Description

Technical Field

[0001] This invention relates to the field of hydrogen production by water electrolysis, and more specifically to a multiphase platinum-supported nickel-vanadium layered bimetallic hydroxide electrocatalyst, its preparation method, and its application. Background Technology

[0002] Electrolysis of water to produce hydrogen is a technology that efficiently converts electrical energy from renewable energy sources (such as solar and wind power) into chemical energy stored in hydrogen, achieving sustainable energy recycling. The core reaction of this technology involves two half-reactions: the hydrogen evolution reaction (HER) at the cathode and the oxygen evolution reaction (OER) at the anode. The kinetic rate of the HER at the cathode is relatively slow, which is a key bottleneck restricting the efficiency of water electrolysis for hydrogen production and increasing energy consumption costs. Therefore, developing high-performance hydrogen evolution catalysts has become a core requirement for promoting the large-scale application of water electrolysis for hydrogen production.

[0003] Currently, platinum (Pt)-based materials remain the most active known hydrogen evolution catalysts, but their high price and scarcity severely limit their large-scale industrial application. To reduce the cost of Pt, existing technologies typically employ the method of loading Pt nanoparticles onto carbon supports with high specific surface areas to improve the utilization rate of Pt atoms. However, under actual water electrolysis conditions for hydrogen production, carbon supports are prone to oxidation and corrosion, leading to the aggregation, detachment, or dissolution of the Pt nanoparticles loaded on them. This not only significantly reduces the catalytic activity of the catalyst but also severely affects its long-term stability, further restricting the practical application of Pt-based catalysts.

[0004] In recent years, "single-atom catalysts" have become a research hotspot in the field of catalysis due to their near 100% atom utilization, unique electronic structure, and excellent catalytic activity, demonstrating great potential in the hydrogen evolution reaction. Single-atom catalysts achieve highly efficient catalysis by regulating the electronic structure through the coordination interaction between metal atoms and the support. However, the stability of these catalysts faces severe challenges: in the harsh environment of the water electrolysis hydrogen evolution reaction, especially under actual industrial-grade high current density conditions, the coordination interaction between metal atoms and the support is easily disrupted, leading to structural reorganization and aggregation of single atoms, resulting in rapid catalyst deactivation and making it difficult to balance catalytic activity and long-term stability.

[0005] To address these issues, researchers have proposed constructing a multiphase synergistic catalytic system of "single atom-cluster-nanoparticles." This approach leverages the synergistic effects of different Pt phases to overcome the performance limitations of a single component, achieving a catalytic enhancement effect of "1+1>2," while simultaneously improving the catalyst's activity and stability. However, precisely controlling the loading morphology and proportion of multiphase Pt to construct a structurally homogeneous and performance-controllable multiphase noble metal supported system, and establishing a clear structure-activity relationship between "preparation method, material structure, and catalytic performance," remains a significant technical challenge in this field, and a mature solution has yet to be found.

[0006] In summary, existing hydrogen evolution catalysts suffer from the technical challenge of simultaneously meeting the requirements of "high catalytic activity, long-term stability, and low preparation cost." Developing a novel hydrogen evolution catalyst that can meet these performance requirements and is suitable for industrial-scale water electrolysis hydrogen production is of significant practical importance and application value for promoting the large-scale application of water electrolysis hydrogen production technology. Summary of the Invention

[0007] To address the problems of low atom utilization, imbalance between activity and stability, easy dissolution and deactivation of nanocatalysts in alkaline electrolytes, and limited performance due to the need for binders in electrode fabrication, this invention aims to provide a multiphase platinum-supported nickel-vanadium layered bimetallic hydroxide electrocatalyst, its preparation method, and its application.

[0008] The preparation method of the multiphase platinum-supported nickel-vanadium layered bimetallic hydroxide electrocatalyst according to the present invention includes the following steps: S1, pretreating nickel foam to remove its surface oxide layer and oil stains; S2, dissolving nickel salt and vanadium salt in deionized water to obtain a nickel-vanadium salt mixed solution, wherein the nickel salt and vanadium salt provide Ni 2+ and V 3+ The molar ratio of ammonium fluoride to urea is 1:1 to 5:1; S3, ammonium fluoride and urea are added to the nickel-vanadium salt mixed solution for adjustment, and stirred to obtain a mixed solution, wherein the molar ratio of ammonium fluoride to urea is 0.8:1 to 1.5:1; S4, the adjusted mixed solution is mixed with pretreated foamed nickel, and a hydrothermal reaction is carried out to obtain nickel-vanadium layered bimetallic hydroxide. After the hydrothermal reaction, it is washed and dried to obtain a self-supporting precursor; S5, the self-supporting precursor is immersed in a Pt-containing salt aqueous solution that has been pretreated with inert gas to remove oxygen. After immersion, it is washed and dried to obtain a multiphase platinum-supported intermediate; S6, the multiphase platinum-supported intermediate is placed under an inert atmosphere and calcined to obtain a multiphase platinum-supported nickel-vanadium layered bimetallic hydroxide electrocatalyst.

[0009] In a preferred embodiment, in step S1, the nickel foam is ultrasonically cleaned sequentially with water, ethanol, dilute hydrochloric acid, and water, and no drying is required after cleaning.

[0010] In a preferred embodiment, in step S2, the nickel salt is nickel chloride hexahydrate, and the vanadium salt is vanadium trichloride; the feeding sequence is to first add the nickel salt to dissolve it, and then add the vanadium salt; the nickel salt and vanadium salt provide Ni 2+ and V 3+ The total concentration is 15~70 mmol / L.

[0011] In a preferred embodiment, in step S3, the concentration of urea is 55~110 mmol / L; after ammonium fluoride and urea are added, the stirring time does not exceed 20 min.

[0012] In a preferred embodiment, in step S4, the hydrothermal reaction temperature is 110~130℃ and the hydrothermal reaction time is 12~24h; the hydrothermal reaction uses a stainless steel reactor lined with polytetrafluoroethylene; the drying is vacuum drying, the vacuum drying temperature is 50~70℃ and the drying time is 12~24h.

[0013] In a preferred embodiment, in step S5, the Pt-containing salt aqueous solution is an aqueous solution of chloroplatinic acid hexahydrate with a concentration of 0.3~0.8 mg / mL; the inert gas is argon or nitrogen, and the purging time is not less than 1 hour; the soaking time is 2~12 hours; the drying is vacuum drying, with a vacuum drying temperature of 50~70℃ and a drying time of 12~24 hours.

[0014] In a preferred embodiment, in step S6, the temperature is increased to 110-130°C at a heating rate of 5-10°C / min for calcination; the calcination time is 1-3 hours; and the inert gas is argon or nitrogen.

[0015] The multiphase platinum-supported nickel-vanadium layered bimetallic hydroxide electrocatalyst of the present invention is prepared by the above-described preparation method. The electrocatalyst uses nickel foam as a self-supporting support, and nanosheet-like nickel-vanadium layered bimetallic hydroxide is grown on the surface of the support. The surface of the nickel-vanadium layered bimetallic hydroxide is loaded with multiphase Pt.

[0016] In a preferred embodiment, the size of the nanosheet-like nickel-vanadium layered bimetallic hydroxide is 500~1000 nm; the multiphase Pt includes single-atom substitution, single-atom support, clusters and nanoparticles, wherein the particle size of the Pt nanoparticles is <1 μm; the molar ratio of Pt:Ni:V in the multiphase platinum-supported nickel-vanadium layered bimetallic hydroxide electrocatalyst is 3:3:1~5:5:1.

[0017] The present invention relates to the application of the above-described multiphase platinum-supported nickel-vanadium layered bimetallic hydroxide electrocatalyst as a cathode hydrogen evolution catalyst or electrode in alkaline water electrolysis for hydrogen production.

[0018] This invention successfully solves the technical problems of traditional Pt-based catalysts, such as low atom utilization, imbalance between activity and stability, easy dissolution and deactivation of nanocatalysts in alkaline electrolytes, and performance limitations caused by the reliance on binders in electrode preparation, through an integrated preparation method involving nickel foam pretreatment, mixing of nickel and vanadium salts in a specific ratio, synergistic regulation of ammonium fluoride and urea, hydrothermal preparation of a self-supporting precursor, controllable loading of multiphase Pt by argon oxygen removal, and low-temperature inert atmosphere calcination. The prepared multiphase platinum-supported nickel-vanadium layered bimetallic hydroxide electrocatalyst uses nickel foam as a self-supporting carrier and can be used directly as an electrode without additional binders. It not only has a larger specific surface area and a higher density of catalytic active sites, but also significantly improves the cathode hydrogen evolution activity and long-term stability in alkaline water electrolysis hydrogen production scenarios through the synergistic effect of multiphase Pt and NiV LDHs substrate. At the same time, the preparation process is simple, convenient to operate, and has low energy consumption, which can realize scale-up production from small scale to large scale. It provides a highly efficient, stable, and easily industrially applicable catalytic material and preparation scheme for alkaline water electrolysis hydrogen production. Attached Figure Description

[0019] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0020] Figure 1 XPS image of the multiphase platinum-supported nickel-vanadium layered bimetallic hydroxide electrocatalyst prepared in Example 1 of this invention.

[0021] Figure 2 This is a SEM image of the multiphase platinum-supported nickel-vanadium layered bimetallic hydroxide electrocatalyst prepared in Example 1 of the present invention.

[0022] Figure 3 The image shows an HR-TEM image of the multiphase platinum-supported nickel-vanadium layered bimetallic hydroxide electrocatalyst prepared in Example 1 of this invention.

[0023] Figure 4 This is an extended X-ray absorption fine structure (EXAFS) image of the PtL3-edge of the multiphase platinum-supported nickel-vanadium layered bimetallic hydroxide electrocatalyst prepared in Example 1 of this invention.

[0024] Figure 5 The hydrogen evolution polarization curves of the multiphase platinum-supported nickel-vanadium layered bimetallic hydroxide electrocatalysts prepared in Examples 1, 1, and 2 of this invention in 1.0 mol / L KOH are shown.

[0025] Figure 6 The multiphase platinum-supported nickel-vanadium layered bimetallic hydroxide electrocatalysts prepared in Examples 1, 1, and 2 of this invention, at a hydrogen evolution current density of 1000 mA / cm², [are used in this study]. 2The overpotential was compared at the beginning and after 4000 CV cycles. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] According to a first aspect of the present invention, a method for preparing a multiphase platinum-supported nickel-vanadium layered bimetallic hydroxide electrocatalyst is provided, which first includes pretreatment of nickel foam (NF). The purpose of this pretreatment is to remove the surface oxide layer and oil contaminants to better grow NiV LDH nanosheets. In a preferred embodiment, the pretreatment includes: sequentially washing the nickel foam substrate with water, ethanol, dilute hydrochloric acid (e.g., 3 mol / L hydrochloric acid), and water alternately, and then setting it aside for later use. In a preferred embodiment, the washing process uses ultrasonic cleaning for 5-10 minutes. In a preferred embodiment, the final cleaning is with deionized water, and drying is not required after cleaning. In a preferred embodiment, the substrate is first immersed in deionized water and ultrasonically cleaned for 5-10 minutes, then ultrasonically cleaned in anhydrous ethanol for 5-10 minutes, followed by ultrasonic cleaning in 3M hydrochloric acid for 5-10 minutes, and finally ultrasonically cleaned in deionized water until neutral.

[0028] The method for preparing the multiphase platinum-supported nickel-vanadium layered bimetallic hydroxide electrocatalyst according to the first aspect of the present invention further includes dissolving a nickel salt and a vanadium salt in deionized water to obtain a nickel-vanadium salt mixed solution. In a preferred embodiment, the nickel salt comprises nickel chloride hexahydrate, and the vanadium salt comprises vanadium trichloride. In a preferred embodiment, the nickel salt and vanadium salt are prepared according to Ni... 2+ and V 3+ The molar ratio is 1:1 to 5:1, such as 1:1, 2:1, 3:1, 4:1, or 5:1. Nickel salts and vanadium salts are classified according to Ni... 2+ and V 3+ The total concentration is 15-70 mmol / L. In a preferred embodiment, the nickel salt is added first, followed by the vanadium salt, to prevent oxidation or hydrolysis of the vanadium salt.

[0029] The method for preparing the multiphase platinum-supported nickel-vanadium layered bimetallic hydroxide electrocatalyst according to the first aspect of the present invention further includes adding ammonium fluoride (NH4F) and urea (CO(NH2)2) to a nickel-vanadium salt mixed solution for adjustment, and stirring to obtain a mixed solution. In a preferred embodiment, the molar ratio of ammonium fluoride to urea is 0.8:1 to 1.5:1, wherein the concentration of urea is 55 to 110 mmol / L. In a preferred embodiment, after adding ammonium fluoride and urea, the stirring time does not exceed 20 min to prevent oxidation or hydrolysis of the vanadium salt.

[0030] The method for preparing the multiphase platinum-supported nickel-vanadium layered bimetallic hydroxide electrocatalyst according to the first aspect of the present invention further includes mixing a conditioned mixed solution with pretreated nickel foam, and performing a hydrothermal reaction to obtain nickel-vanadium layered bimetallic hydroxides (NiV LDHs). After the hydrothermal reaction, the mixture is washed and dried to obtain a self-supporting precursor, namely NiV LDHs / NF. In a preferred embodiment, the hydrothermal reaction is carried out in a stainless steel reactor lined with polytetrafluoroethylene, the hydrothermal reaction temperature is 110~130℃ (e.g., 120℃), and the reaction time is 12~24h. In a preferred embodiment, during the hydrothermal reaction, the pretreated nickel foam is vertically placed into the mixed solution using a fixing device and completely immersed to ensure that the grown NiV LDHs grow uniformly and orderly on the surface of the nickel foam. In a preferred embodiment, the product generated after the hydrothermal reaction is removed, washed only with deionized water, and vacuum dried. In a preferred embodiment, the vacuum drying temperature is 50~70℃, and the drying time is 12~24 hours.

[0031] The method for preparing the multiphase platinum-supported nickel-vanadium layered bimetallic hydroxide electrocatalyst according to the first aspect of the present invention further includes immersing a self-supporting precursor NiV LDHs / NF in an aqueous solution containing Pt salt, followed by washing and drying to obtain the multiphase platinum-supported intermediate Pt-NiV LDHs-Ar. In a preferred embodiment, the aqueous solution containing Pt salt is an aqueous solution of chloroplatinic acid hexahydrate (H2PtCl6·6H2O). In a preferred embodiment, the concentration of the aqueous solution is 0.3-0.8 mg / mL (e.g., 0.45 mg / mL, 0.5 mg / mL, 0.6 mg / mL). In a preferred embodiment, the immersion time is 2-12 h. In a preferred embodiment, the Pt-containing salt aqueous solution is pre-purged with Ar or N2 gas (e.g., argon gas is continuously purged for at least 1 hour) to completely remove O2 from the solution. This aims to reduce the spontaneous oxygen absorption corrosion process on the metal surface, adjust the pH near the substrate-liquid interface, optimize the Pt deposition rate, and controllably form multi-phase Pt deposition, including single atoms (particle size <0.5 nm) with individually attached Pt atoms, clusters of 2 to hundreds of atoms (particle size 0.5~10 nm), and nanoparticles (preferably 10~100 nm) with more atoms arranged in an ordered manner. In a preferred embodiment, the intermediate formed after soaking is removed, washed only with deionized water, and vacuum dried. In a preferred embodiment, the vacuum drying temperature is 50~70°C, and the drying time is 12~24 hours.

[0032] The preparation method of the multiphase platinum-supported nickel-vanadium layered bimetallic hydroxide electrocatalyst according to the first aspect of the present invention finally includes calcining the multiphase platinum-supported intermediate Pt-NiV LDHs-Ar in a tube furnace. After calcination, the final product Pt-NiV LDHs-Ar-C is obtained. Calcination can enhance the interaction between Pt and the substrate, and simultaneously promote the interconversion of Pt single atoms, clusters, or nanoparticles, optimizing their ratio and achieving a synergistic improvement in activity and stability. In a preferred embodiment, the atmosphere during calcination is argon or nitrogen. In a preferred embodiment, the calcination temperature is 110℃-130℃ (e.g., 120℃). In a preferred embodiment, the calcination time is 1~3h (e.g., 1h, 2h, or 3h). In a preferred embodiment, the heating rate during calcination is 5~10℃ / min (e.g., 5℃ / min, 6℃ / min, 8℃ / min, 10℃ / min).

[0033] According to a second aspect of the present invention, a multiphase platinum-supported nickel-vanadium layered bimetallic hydroxide electrocatalyst obtained by the above-described preparation method is provided. This electrocatalyst uses conductive nickel foam (NF) as a self-supporting carrier and is used directly as an electrode. Nanosheet-like nickel-vanadium layered bimetallic hydroxides (NiV LDHs) are grown on the surface of the carrier, and multiphase platinum is attached to the NiV LDHs to form a three-dimensional composite catalyst structure. The NiV LDHs are an ordered array structure grown on a three-dimensional nickel foam substrate via a hydrothermal method, providing abundant anchoring sites for Pt loading. In a preferred embodiment, the NiV LDH nanosheets have a size of 500-1000 nm, and their chemical composition uses nickel hydroxide as the layered matrix, and is obtained through V... 3+ It is formed by replacing some nickel ions and exhibits typical characteristics of layered bimetallic hydroxides; the oxidation state of Ni is +2, and that of V is +3 / +4 / +5, with the surface rich in hydroxyl groups (OH-). - Furthermore, the high-valence V possesses coordination unsaturated sites and dangling bonds, which can firmly immobilize Pt species. Pt loaded on the surface of NiV LDHs nanosheets exists in a multi-phase form, specifically including single-atom substitution, single-atom loading, clusters, and nanoparticles. This characteristic stems from the synergistic effect of "argon gas oxygen removal to regulate the Pt deposition rate" and "low-temperature calcination to optimize the phase ratio" during the preparation process, which is also the core reason for the catalyst's high activity and high stability. In a preferred embodiment, the Pt nanoparticle size is <1 μm. In a preferred embodiment, the Pt:Ni:V molar ratio in this electrocatalyst is in the range of 3:3:1 to 5:5:1.

[0034] According to a third aspect of the invention, the above-described electrocatalyst is provided for use as a cathode hydrogen evolution catalyst or electrode. In a preferred embodiment, the electrode is prepared by shearing a multiphase platinum-supported nickel-vanadium layered bimetallic hydroxide electrocatalyst to a suitable size.

[0035] Example 1

[0036] Cut out a size of 2×4cm 2 Using nickel foam (NF) as a substrate, it was sequentially immersed in deionized water, anhydrous ethanol, and 3M hydrochloric acid, and ultrasonically cleaned for 5-10 minutes each. Finally, it was ultrasonically cleaned in deionized water until the solution was neutral. After cleaning, the nickel foam was immersed in deionized water for later use (no drying required).

[0037] Weigh 0.285g of nickel chloride hexahydrate (NiCl2·6H2O) and 0.047g of vanadium trichloride (VCl3), dissolve them in 40mL of deionized water, and stir until completely dissolved.

[0038] Add 0.111g of ammonium fluoride (NH4F) and 0.15g of urea (CO(NH2)2) to the above mixed salt solution, and stir for 10 minutes until the mixture is homogeneous.

[0039] Mix the solution with the pretreated 2×4cm 2 Nickel foam was transferred to a 50 mL stainless steel PTFE-lined autoclave. The nickel foam was then vertically immersed in the mixed solution using a fixing device to ensure uniform and orderly growth of NiV LDHs. The autoclave was then subjected to a hydrothermal reaction at 120°C for 12 hours to obtain a yellowish-brown precursor of nickel-vanadium layered bimetallic hydroxides (NiV LDHs). Its chemical composition is as follows: using nickel hydroxide as a layered matrix, through V… 3+ The nickel foam is partially replaced to form a layered bimetallic hydroxide with typical characteristics. After the reaction is complete, the nickel foam is removed, washed with deionized water only, and dried in a vacuum drying oven at 60°C for 12 hours to obtain the self-supporting precursor, namely NiV LDHs / NF.

[0040] Cut out 2×2cm 2 The NiV LDHs / NF precursor was immersed in an aqueous solution of chloroplatinic acid hexahydrate (H2PtCl6·6H2O) pre-treated with argon (Ar) gas for oxygen removal. The concentration of the aqueous solution was 0.5 mg / mL, the volume was 20 mL, and the immersion time was 2 hours. After immersion, the sample was removed, rinsed only with deionized water, and dried in a vacuum drying oven at 60 °C for 12 hours to obtain the intermediate product Pt-NiV LDHs-Ar.

[0041] Pt-NiV LDHs-Ar was placed in a tube furnace and calcined under an argon atmosphere at 120°C for 1 hour at a heating rate of 5°C / min. No further cleaning was required after calcination, and the final product, Pt-NiV LDHs-Ar-C, was obtained directly. This product is yellowish-brown with a gray surface.

[0042] Figure 1 The X-ray photoelectron spectroscopy (XPS) spectrum of the Pt4f orbital of the Pt-NiV LDHs-Ar-C prepared in this embodiment shows multiple characteristic peaks, among which the characteristic peaks at 71.26 eV and 74.62 eV correspond to Pt4f orbitals. 0 The valence states belong to Pt4f respectively. 7 / 2 and Pt 4f 5 / 2 The orbital, the metallic Pt0 peak corresponds to the existence of Pt clusters or nanoparticles, indicating that PtCl6 2− The reactants were reduced; and the characteristic peaks at 72.74 eV and 76.17 eV correspond to Pt. 2+Valence state; characteristic peaks at 73.68 eV and 77.58 eV correspond to Pt 4+ Price state, the above Pt 2+ / Pt 4+ The Pt is in the oxidized state, mainly corresponding to different degrees of coordination between the single-atom Pt and the substrate providing O. The characteristic peaks of each valence state in this spectrum all exhibit significant signal intensity, directly proving that in the Pt-NiV LDHs-Ar-C prepared in this invention, Pt exists in a multiphase form (including metallic Pt). 0 Oxidized Pt 2+ and Pt 4+ This study verified the design concept of multiphase platinum loading for Pt species in different aggregation states, such as single atoms, clusters, and nanoparticles, laying a structural foundation for the synergistic effect of each phase in the subsequent catalytic process.

[0043] Figure 2 This is a scanning electron microscope (SEM) image of the Pt-NiV LDHs-Ar-C prepared in Example 1. The image shows a uniformly ordered array of nanosheets with a diameter <1µm grown on the surface of the nickel foam substrate. Simultaneously, granular material with a diameter of approximately 100nm, representing Pt nanoparticles, can be observed on the nanosheet surface. Single-atom and cluster-shaped Pt particles are too small to be directly observed by SEM, but can be observed by combining... Figure 1 XPS results confirm its existence. This spectrum verifies that NiVLDHs grow in an ordered manner on nickel foam in the form of ultrathin nanosheets, and the three-dimensional ordered structure provides a larger specific surface area and more catalytic active sites. Simultaneously, it demonstrates that Pt species are successfully loaded onto the surface of NiVLDHs nanosheets, forming a composite structure of "nickel foam-NiVLDHs nanosheets-multiphase Pt." This structure facilitates electron transport and electrolyte penetration, providing morphological support for excellent catalytic performance.

[0044] Figure 3 The high-resolution transmission electron microscope (HR-TEM) image of the Pt-NiV LDHs-Ar-C prepared in Example 1 shows that the approximately 1.39 Å lattice fringes correspond to the platinum (220) crystal plane in the selected area electron diffraction (SAED) pattern shown in the upper right inset. This indicates that the sample contains long-range order of face-centered cubic (fcc) platinum crystals, i.e., Pt 0 Nanoparticles with a particle size of at least 2 nm.

[0045] Figure 4This is an extended X-ray absorption fine structure (EXAFS) image of Pt L3-edge in the Pt-NiV LDHs-Ar-C prepared in Example 1. The Pt L3-edge EXAFS spectrum depicts the coordination environment of Pt, with two main peaks simultaneously present in the range of 0-4.0 Å. The first coordination shell scattering peak at ~1.6 Å represents Pt-O coordination, corresponding to single-atom Pt structures in multiphase Pt; while the second coordination shell scattering peak at ~2.3 Å corresponds to Pt-Pt coordination, corresponding to Pt clusters or nanoparticles in multiphase Pt. Combined with... Figure 1 The XPS peak fractionation results confirm the successful synthesis of the multiphase Pt structure.

[0046] Example 2

[0047] Cut out a size of 4×8cm 2 The nickel foam (NF) is sequentially ultrasonically cleaned with deionized water, anhydrous ethanol, and 3M hydrochloric acid for 5-10 minutes, and finally ultrasonically cleaned with deionized water until neutral, and then immersed in water for later use.

[0048] Weigh 0.567g of nickel chloride hexahydrate (NiCl2·6H2O) and 0.188g of vanadium trichloride (VCl3), and dissolve them in 120 mL of deionized water in the order of nickel salt first and then vanadium salt.

[0049] Add 0.444g of ammonium fluoride (NH4F) and 0.6g of urea (CO(NH2)2) to the mixed salt solution and stir for 10 minutes until homogeneous.

[0050] Mix the solution with the pretreated 4×8cm 2 Nickel foam was transferred to a 200 mL stainless steel PTFE-lined autoclave, vertically fixed and completely submerged, and hydrothermally reacted at 120 °C for 18 hours. After the reaction, it was washed with deionized water and vacuum dried at 60 °C for 12 hours to obtain the NiV LDHs / NF precursor (yellowish-brown).

[0051] 4×8cm 2 NiV LDHs / NF were directly immersed in a 0.5 mg / mL aqueous solution of chloroplatinic acid hexahydrate (H2PtCl6·6H2O) that had been pre-treated with argon for oxygen removal (≥1 hour) (volume 100 mL). After immersion for 2 hours, the solution was washed with deionized water and dried under vacuum at 60 °C for 12 hours to obtain Pt-NiV LDHs-Ar.

[0052] Pt-NiV LDHs-Ar was placed in a tube furnace and calcined at 120°C for 2 hours under an argon atmosphere with a heating rate of 5°C / min. After calcination, the final product Pt-NiV LDHs-Ar-C (yellowish-brown with a gray surface) was obtained.

[0053] Example 3

[0054] Cut out a size of 10×16cm 2 Nickel foam (NF) is ultrasonicated sequentially with deionized water, anhydrous ethanol, and 3M hydrochloric acid for 5-10 minutes, and finally ultrasonicated with deionized water until neutral, then immersed for later use.

[0055] Weigh 7.125g of nickel chloride hexahydrate (NiCl2·6H2O) and 1.175g of vanadium trichloride (VCl3), and dissolve them in 600 mL of deionized water in the order of nickel salt first and then vanadium salt.

[0056] Add 2.775g of ammonium fluoride (NH4F) and 3.75g of urea (CO(NH2)2) to the mixed salt solution and stir for 10 minutes until homogeneous.

[0057] Mix the solution with the pretreated 10×16cm 2 Nickel foam was transferred to a 1L stainless steel PTFE-lined autoclave, vertically fixed and completely submerged, and hydrothermally reacted at 120°C for 24 hours. After the reaction, it was washed with deionized water and vacuum dried at 60°C for 12 hours to obtain the NiV LDHs / NF precursor (yellowish-brown).

[0058] 10×16cm 2 NiV LDHs / NF was immersed in an aqueous solution of 0.5 mg / mL chloroplatinic acid hexahydrate (H2PtCl6·6H2O) that had been pre-treated with argon for oxygen removal (≥1 hour) (800 mL volume). After immersion for 2 hours, it was washed with deionized water and dried under vacuum at 60 °C for 12 hours to obtain Pt-NiV LDHs-Ar.

[0059] Pt-NiV LDHs-Ar was placed in a tube furnace and calcined at 120°C for 1.5 hours under an argon atmosphere with a heating rate of 8°C / min. The final product Pt-NiV LDHs-Ar-C (yellowish-brown with a gray surface) was obtained after calcination.

[0060] Comparative Example 1

[0061] The preparation method of this comparative example is basically the same as that of Example 1. The core difference is that the aqueous solution of chloroplatinic acid hexahydrate was not subjected to argon oxygen removal treatment and the argon calcination process was omitted, and the final product Pt-NiV LDHs-O2 was obtained.

[0062] Comparative Example 2

[0063] The preparation method of this comparative example is basically the same as that of Example 1. The core difference is that the argon calcination process is omitted, and the final product Pt-NiV LDHs-Ar is obtained.

[0064] Application Example 1

[0065] The hydrogen evolution reaction (HER) performance of the Pt-NiV LDHs-Ar-C prepared in Example 1 was tested using a three-electrode system under the following specific test conditions:

[0066] Electrolyte: 1.0 mol / L KOH aqueous solution;

[0067] Reference electrode: Ag / AgCl electrode;

[0068] Counter electrode: 2cm 2 Nickel foam;

[0069] Working electrode: The Pt-NiV LDHs-Ar-C prepared in Example 1 was cut into 0.5 × 1 cm pieces. 2 The size is directly used as a self-supporting working electrode;

[0070] Test parameters: Test the hydrogen evolution polarization curve (including internal resistance compensation) and conduct 4000 cycles of CV accelerated aging test to compare the catalytic performance before and after aging;

[0071] Test parameters: The focus is on the hydrogen evolution overpotential and stability at an industrial-grade current density of 1000 mA / cm².

[0072] Application Comparative Example 1

[0073] The test system was the same as in Application Example 1, except that the working electrode was replaced with Pt-NiV LDHs-O2 prepared in Comparative Example 1 (cut to 0.5 × 1 cm). 2 ), 4cm 2 Nickel felt was used as the counter electrode to test the initial hydrogen evolution overpotential under the same current density and the overpotential change after 4000 cycles of CV aging.

[0074] Application Comparative Example 2

[0075] The test system was the same as in Application Example 1, except that the working electrode was replaced with Pt-NiV LDHs-Ar (cut to 0.5 × 1 cm²) prepared in Comparative Example 2, 4 cm 2 Nickel felt was used as the counter electrode to test the initial hydrogen evolution overpotential under the same current density and the overpotential change after 4000 cycles of CV aging.

[0076] Figure 5This is a hydrogen evolution polarization curve. The curve shows the hydrogen evolution polarization curves in a three-electrode system (1.0 mol / L KOH electrolyte), including the initial state and the curves after 4000 cycles of CV accelerated aging. Internal resistance compensation has been applied to the polarization curves. A more positive onset potential and a higher current density at the same potential indicate higher catalytic activity. As can be seen from the figure, in the initial state, the Pt-NiV LDHs-Ar-C in Example 1 has the most positive onset potential, reaching -1000 mA / cm² at approximately -0.24 V. 2 The industrial-grade current density of the catalyst resulted in significantly better catalytic activity than Comparative Example 1 (Pt-NiV LDHs-O2) and Comparative Example 2 (Pt-NiV LDHs-Ar). After 4000 cycles of accelerated CV aging, the Pt-NiV LDHs-O2 curve of Comparative Example 1 showed a significant negative shift (a substantial decrease in current density), the Pt-NiV LDHs-Ar curve of Comparative Example 2 showed a slight negative shift, while the Pt-NiV LDHs-Ar-C curve of Example 1 remained almost unchanged, demonstrating its superior catalytic stability. The comparative results indicate that the "argon oxygen removal" and "argon calcination" steps in the preparation process are key to improving the catalyst's activity and stability, and their synergistic effect achieves optimized loading and structural stability of multiphase Pt.

[0077] Figure 6 This is a comparison of overpotentials at a current density of 1000 mA / cm². In Comparative Example 1, the initial overpotential of Pt-NiV LDHs-O2 was 246 mV, and after 4000 cycles of CV, the overpotential was 301 mV. In Comparative Example 2, the initial overpotential of Pt-NiV LDHs-Ar was 245 mV, and after 4000 cycles of CV, the overpotential was 249 mV. In Example 1, the initial overpotential of Pt-NiV LDHs-Ar-C was 227 mV, and after 4000 cycles of CV, the overpotential was 226 mV. Overpotential is a core indicator for evaluating the activity of hydrogen evolution catalysts; the lower the overpotential, the higher the catalytic activity; the smaller the change in overpotential before and after aging, the better the stability. As can be seen from the figure, in the initial state, the overpotential of Pt-NiVLDHs-Ar-C in Example 1 (227 mV) is the lowest compared to other comparisons, lower than Comparative Example 1 (246 mV) and Comparative Example 2 (245 mV), proving that its hydrogen evolution activity is the best. After 4000 cycles of CV aging, the overpotential of Pt-NiV LDHs-Ar-C in Example 1 only changed by 1 mV, with almost no decay; while the overpotential of Comparative Example 1 increased by 55 mV and the overpotential of Comparative Example 2 increased by 4 mV, proving that the catalyst of Example 1 has a long-term stability far exceeding that of the comparison samples. This data directly verifies the superiority of the preparation method of the present invention. Through the synergistic design of "argon gas oxygen removal to regulate Pt deposition rate" and "low-temperature calcination to enhance the interaction between Pt and substrate", the catalytic activity and stability are improved simultaneously, meeting the working conditions requirements of industrial-grade water electrolysis for hydrogen production.

[0078] This invention successfully prepared a multiphase platinum-supported nickel-vanadium layered bimetallic hydroxide electrocatalyst (Pt-NiV LDHs-Ar-C) using a three-step method: hydrothermal preparation of NiV LDHs precursor, argon-gas oxygen removal immersion loading of multiphase Pt, and low-temperature calcination. The preparation method uses nickel and vanadium salts as raw materials to form a layered bimetallic hydroxide as the supporting substrate, with chloroplatinic acid as the platinum source. During the immersion process, argon gas oxygen removal is used to adjust the pH near the substrate-liquid interface, optimizing the Pt deposition rate and controllably forming multiphase Pt deposition, including single atoms, clusters, and nanoparticles. Subsequent calcination in a relatively low-temperature argon / nitrogen atmosphere enhances the interaction between Pt and the substrate and induces the interconversion and optimization of different Pt phases. Examples 1-3 demonstrate that this preparation method can achieve large-scale production from small to large scale, with a simple process, readily available raw materials, no need for complex pH control of the reaction solution, low-temperature heating with low energy consumption advantages, and partial solvent reuse, making it more environmentally friendly. The prepared catalyst is a microporous-mesoporous material with an ordered arrangement, which can be directly synthesized into a three-dimensional ordered electrode structure, avoiding the use of binders. It belongs to the low-noble metal Pt loading hydroxide-based three-dimensional self-supporting electrode, which is expected to significantly reduce the cost of hydrogen production. It is worth noting that general nanomaterial electrocatalysts are prone to dissolution in strong acid or strong base electrolytes, resulting in loss of active components and reduced stability. However, the catalyst of this invention is composed of ultra-small or ultra-thin nanomaterials with a multi-level superstructure of nanostructures, which can overcome this shortcoming and significantly improve the structural stability of the catalyst in alkaline electrolysis environment. Performance test results show that the catalyst exhibits excellent electrocatalytic hydrogen evolution (HER) performance in alkaline electrolytes; and it has high mass activity, exhibiting excellent alkaline HER catalytic activity and stability at industrial current densities, making it suitable for market promotion and application. Its superior performance stems from the "three-dimensional ordered NiV LDH nanosheet structure" and the "synergistic effect of multiphase Pt." Compared to traditional bulk electrocatalysts, this nanostructured catalyst has a larger specific surface area and a higher density of catalytic active sites, while also possessing structural stability similar to bulk materials. This effectively suppresses performance deactivation caused by catalyst aggregation, dissolution, and shedding, successfully addressing the technical pain points of traditional Pt-based catalysts, such as low atom utilization, poor stability, and high energy consumption in hydrogen production. This catalyst can be directly applied to the cathode hydrogen evolution reaction in alkaline water electrolysis for hydrogen production, serving as both a catalyst and a direct electrode. It significantly reduces energy consumption and cost in the hydrogen production process, demonstrating outstanding practical application prospects and suitability for industrial-scale promotion and application.

[0079] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a polyphase platinum-supported nickel-vanadium layered double hydroxide electrocatalyst, characterized in that, The preparation method comprises the following steps: S1, pretreating the foamed nickel to remove the surface oxide layer and oil stains; S2, dissolving the nickel salt and the vanadium salt in deionized water to obtain a mixed solution of nickel vanadium salt, wherein the nickel salt and the vanadium salt provide a molar ratio of Ni 2+ and V 3+ of 1:1~5:1; S3, adding ammonium fluoride and urea into the nickel vanadium salt mixed solution for adjustment, and stirring and mixing to obtain a mixed solution, wherein the molar ratio of the ammonium fluoride to the urea is 0.8:1-1.5:1; S4, mixing the adjusted mixed solution with the pretreated foamed nickel, and performing hydrothermal reaction to obtain a nickel vanadium layered double hydroxide, and performing cleaning and drying after the hydrothermal reaction to obtain a self-supporting precursor; S5, immersing the self-supporting precursor in a Pt salt-containing aqueous solution which is pre-treated by being purged with an inert gas to remove oxygen, and performing cleaning and drying after the immersion to obtain a multi-phase platinum-loaded intermediate; S6, placing the multi-phase platinum-loaded intermediate in an inert atmosphere, and performing calcination to obtain a multi-phase platinum-loaded nickel vanadium layered double hydroxide electrocatalyst.

2. The production method according to claim 1, characterized by, In step S1, the foamed nickel is sequentially cleaned with water, ethanol, dilute hydrochloric acid, and water under ultrasonic cleaning, and does not need to be dried after cleaning.

3. The preparation method according to claim 1, characterized in that, In step S2, the nickel salt is nickel chloride hexahydrate, and the vanadium salt is vanadium trichloride; the feeding sequence is to dissolve the nickel salt first, and then add the vanadium salt; the nickel salt and the vanadium salt provide a total concentration of Ni 2+ and V 3+ of 15-70 mmol / L.

4. The method of claim 1, wherein, In step S3, the concentration of the urea is 55-110 mmol / L; and after the ammonium fluoride and the urea are added, the stirring time is not more than 20 min.

5. The preparation method according to claim 1, characterized in that, In step S4, the temperature of the hydrothermal reaction is 110-130 ℃, and the time of the hydrothermal reaction is 12-24 h; the hydrothermal reaction is performed in a polytetrafluoroethylene-lined stainless steel reaction kettle; and the drying is vacuum drying, the vacuum drying temperature is 50-70 ℃, and the drying time is 12-24 h.

6. The method of claim 1, wherein, In step S5, the Pt salt-containing aqueous solution is an aqueous solution of chloroplatinic acid hexahydrate with a concentration of 0.3-0.8 mg / mL; the inert gas is argon or nitrogen, and the purging time is not less than 1 h; the immersion time is 2-12 h; and the drying is vacuum drying, the vacuum drying temperature is 50-70 ℃, and the drying time is 12-24 h.

7. The preparation method according to claim 1, characterized in that, In step S6, the calcination is performed at a temperature increasing rate of 5-10 ℃ / min to 110-130 ℃; the calcination time is 1-3 h; and the inert gas is argon or nitrogen.

8. A multi-phase platinum supported nickel vanadium layered double hydroxide electrocatalyst characterized by, Prepared by the preparation method in any one of claims 1-7, the electrocatalyst has a foamed nickel as a self-supporting carrier, nanosheet-shaped nickel vanadium layered double hydroxide grows on the surface of the carrier, and the surface of the nickel vanadium layered double hydroxide is loaded with multi-phase Pt.

9. The multiphasic platinum-supported nickel vanadium layered double hydroxide electrocatalyst of claim 8, wherein, The size of the nanosheet-shaped nickel vanadium layered double hydroxide is 500-1000 nm; the multi-phase Pt includes single-atom substitution, single-atom loading, clusters, and nanoparticles, wherein the particle size of the Pt nanoparticles is <1 μm; and the molar ratio of Pt:Ni:V in the multi-phase platinum-loaded nickel vanadium layered double hydroxide electrocatalyst is 3:3:1-5:5:

1.

10. Application of the multi-phase platinum-loaded nickel vanadium layered double hydroxide electrocatalyst in claim 8 or 9 as a cathode hydrogen evolution catalyst or electrode in alkaline electrolytic water hydrogen production.

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