Preparation of a foam nickel supported polyacid derivative flower-like vanadium doped nickel molybdenum sulfide

Abstract

The present application relates to the field of electrocatalytic hydrogen evolution, and discloses a preparation method and application of a foam nickel loaded polyacid derivative vanadium doped nickel molybdenum sulfide. The present application aims to solve the problems of raw material shortage, high hydrogen evolution overpotential and high cost in the prior art for synthesizing high-performance electrocatalysts. The present application designs and develops a foam nickel loaded vanadium doped nickel molybdenum sulfide material V-MoS2 / Ni3S2@NF-Mo. The method comprises the following steps: taking Keplerate type polyacid Mo 72 V 30 , thiourea as a sulfur source, and foam nickel as a conductive substrate, and adopting a one-step hydrothermal synthesis method to prepare foam nickel loaded polyacid derivative flower-like vanadium doped nickel molybdenum sulfide, which can be applied to electrocatalytic hydrogen evolution reaction in an alkaline electrolyte and has low hydrogen evolution overpotential and high catalytic activity.

Description

Technical Field

[0001] This invention relates to the field of electrocatalytic hydrogen evolution, and particularly to the preparation of a nickel-molybdenum sulfide doped with polyacid-derived flower-like vanadium supported on nickel foam. Background Technology

[0002] With the continuous growth of global energy demand and the increasingly prominent environmental problems caused by fossil fuels, hydrogen energy, due to its high energy density and clean combustion characteristics, has become an important direction for energy transformation. Electrochemical Hydrogen Evolution Reaction (HER) is a key technology for producing high-purity hydrogen, but the widely used platinum-based catalysts are limited by scarce reserves and high costs, making large-scale application difficult. Therefore, developing low-cost, highly active, and stable non-precious metal HER catalysts has become a current research focus. Polyoxometalates (POMs) are considered ideal catalyst precursors due to their excellent redox properties, tunable electronic structure, and ease of synthesis. Among them, vanadium-molybdenum-based bimetallic composites can optimize hydrogen adsorption energy and increase the number of active sites through intermetallic electronic interactions, thereby improving HER performance. However, traditional synthesis methods easily lead to material particle agglomeration and poor conductivity, limiting their practical application. Using nickel foam as a support can effectively address these challenges. Its three-dimensional porous structure not only facilitates reaction mass transfer and electron conduction but also allows it to react with the sulfur source during sulfidation, generating the Ni3S2 phase in situ, forming a ternary composite structure. This structure can synergistically promote the exposure of active sites, enhance electron transport efficiency, and improve the structural stability of the material. In summary, the construction of vanadium-doped nickel-molybdenum sulfide composites on nickel foam using polyoxometalates as precursors holds promise for developing high-performance and low-cost HER catalysts, demonstrating significant research value and application prospects. Summary of the Invention

[0003] To overcome the shortcomings of existing electrocatalytic hydrogen evolution catalysts, such as low specific surface area, high price, and poor stability and conductivity of polyacids as raw materials, this invention provides a simple and inexpensive method for preparation. The prepared nickel foam supported polyacid-derived vanadium-doped nickel-molybdenum sulfide has advantages such as high specific surface area, high electrocatalytic performance, and good stability as an electrocatalytic hydrogen evolution catalyst material.

[0004] The objective of this invention is achieved as follows:

[0005] 1. Preparation of a nickel-molybdenum sulfide supported on nickel foam and doped with polyacid-derived vanadium clusters, comprising the following steps:

[0006] (1) 2.6 g NaVO3 was added to 55 mL of distilled water at 60 °C, and 6 g Na2MoO4·2H2O was added to 75 mL of distilled water. Both solutions were stirred for 15 min each and labeled as solution A and solution B, respectively. After solution A cooled to room temperature, the two solutions were mixed and stirred for 15 min. 20 mL of H2SO4 solution was added to the solution and stirred for 15 min. Then 0.9 g of N2H4·H2SO4 was added and stirred for 3 h. Subsequently, 20 mL of KCl solution was added and stirred for 5 min. The mixture was then transferred to an Erlenmeyer flask and left open at room temperature for 4 days. After filtration, the mixture was washed with ethanol and dried at room temperature for 12 h to obtain Mo. 72 V 30 Crystals;

[0007] (2) Add nickel foam (1*1 cm) 2 The sample was placed in a beaker and ultrasonically treated in acetone and concentrated hydrochloric acid solutions for 30 min, followed by ultrasonic cleaning with anhydrous ethanol and deionized water. It was then dehydrated overnight under vacuum at 60°C. 98 mg ammonium fluoride, 200 mg urea and 194 mg nickel nitrate hexahydrate were dissolved in 12 mL of deionized water. At the same time, a pretreated nickel foam substrate was placed in the container. The reaction vessel containing the solution was placed in an oven at 120°C for 10 h. The product was then slowly cooled to room temperature and collected. It was washed several times with distilled water and then in a tube furnace at 500°C under N2 atmosphere to obtain NiO nanorod arrays (NF-MO heterostructure).

[0008] (3) Add 0.11 mg Mo 72 V 30 0.22 mg thiourea was dissolved in 10 mL of deionized water and stirred for 30 min. The solution was then transferred to a 20 mL hydrothermal reactor. A pre-made NF-MO template (2) was immersed in the reaction solution. The reactor was kept at 180°C for 12 h in a temperature-controlled oven and then naturally cooled to room temperature to obtain vanadium-doped nickel-molybdenum sulfide V-MoS2 / Ni3S2@NF-MO supported on nickel foam.

[0009] The above application method is as follows: using a 1.0 mol / L potassium hydroxide aqueous solution as the electrolyte, the nickel foam-supported polyacid-derived vanadium-doped nickel-molybdenum sulfide is used as the working electrode, a saturated calomel electrode is used as the reference electrode, and a carbon rod electrode is used as the counter electrode. In the alkaline electrolyte solution, when the overpotential is 25 mV, the current density is 10 mA·cm⁻¹. -2 It remained stable even after 100 hours of operation.

[0010] Compared with the prior art, the present invention has the following characteristics:

[0011] This invention relates to the preparation and application of a foamed nickel-supported polyacid-derived vanadium-doped nickel-molybdenum sulfide, specifically a vanadium-doped nickel-molybdenum sulfide, in the field of electrocatalytic hydrogen evolution. The purpose of this invention is to address the problems of scarce raw material reserves, high overpotentials in hydrogen evolution reactions, and high costs associated with existing technologies for synthesizing high-performance electrocatalysts. This patent designs and develops a foamed nickel-supported vanadium-doped nickel-molybdenum sulfide material, V-MoS2 / Ni3S2@NF-Mo. The method employed involves using a Keplerate-type polyacid Mo... 72 V 30 Using thiourea as the sulfur source and nickel foam as the conductive substrate, a one-step hydrothermal synthesis method was employed to prepare a polyacid-derived vanadium-doped nickel-molybdenum sulfide supported on nickel foam. This vanadium-doped sulfide exhibits low hydrogen evolution overpotential and high catalytic activity, making it suitable for electrocatalytic hydrogen evolution reaction in alkaline electrolytes. Keplerate-type polyacids provide a stable bimetallic source as a precursor, effectively overcoming the technical bottlenecks of traditional bimetallic sulfide preparation techniques using simple sodium molybdate and metal salts as main raw materials, such as uneven mixing, separation, asynchronous reactions, inconsistent product morphologies, and easy agglomeration of reactants. It also effectively overcomes the drawback of free metal salts having different nucleation rates during hydrothermal processes. Furthermore, it achieves the goal of directional preparation of highly dispersed bimetallic sulfides. The two transition metal sulfides also exhibit a synergistic effect to enhance electrocatalytic performance. When used as an electrocatalytic hydrogen evolution catalyst, this material demonstrates good hydrogen evolution performance and a low overpotential. In alkaline electrolyte solution, at an overpotential of 25 mV, the current density is 10 mA·cm⁻¹. -2 It can maintain a stable working state for 100 hours. The invention employs a simple one-step hydrothermal method to composite a polyacid precursor, thiourea as a sulfur source, with nickel foam, avoiding material agglomeration and enhancing the stability of the electrode over a wide pH range. Without the addition of binders, it not only enhances charge transfer but also avoids the masking of active sites by binders, thereby endowing the electrode with high catalytic activity and achieving a tight bond between the composite material and the conductive material. This improves electron transport capability while enhancing catalyst stability, thus preparing a nickel foam-supported polyacid-derived vanadium-doped nickel-molybdenum sulfide material. Attached Figure Description

[0012] Figure 1 The image shows the XRD pattern of a nickel foam-supported polyacid-derived vanadium-doped nickel-molybdenum sulfide prepared in Example 1 of this invention.

[0013] Figure 2 This is a scanning electron microscope image of a nickel foam-supported polyacid-derived vanadium-doped nickel-molybdenum sulfide prepared in Example 1 of the present invention.

[0014] Figure 3This is a high-resolution transmission electron microscope image of a nickel foam-supported polyacid-derived vanadium-doped nickel-molybdenum sulfide prepared in Example 1 of the invention.

[0015] Figure 4 Hydrogen evolution polarization curves of a foamed nickel-supported polyacid-derived vanadium-doped nickel-molybdenum sulfide and other commercial catalysts prepared in Example 1 of the Invention.

[0016] Figure 5 Electrochemical active area diagram of a nickel foam supported polyacid-derived flower-like vanadium-doped nickel-molybdenum sulfide and other commercial catalysts prepared in Example 1 of the Invention.

[0017] Figure 6 A nickel-molybdenum sulfide supported on a foamed nickel substrate with polyacid-derived flower-like vanadium doped structure, prepared as described in Example 1 of the invention, was prepared at 10 mA·cm⁻¹. -2 Stability graph of stable operation for 100 h at current density. Detailed Implementation

[0018] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0019] Example 1, the preparation of a nickel-molybdenum sulfide supported on nickel foam and doped with polyacid-derived vanadium clusters, includes the following steps:

[0020] (1) 2.6 g NaVO3 was added to 55 mL of distilled water at 60℃, and 6 g Na2MoO4·2H2O was added to 75 mL of distilled water. Both solutions were stirred for 15 min each and labeled as solution A and solution B, respectively. After solution A cooled to room temperature, the two solutions were mixed and stirred for 15 min. 20 mL of H2SO4 solution was added to the solution and stirred for 15 min. Then 0.9 g of N2H4·H2SO4 was added and stirred for 3 h. Subsequently, 20 mL of KCl solution was added and stirred for 5 min. The mixture was then transferred to an Erlenmeyer flask and left open at room temperature for 4 days. After filtration, the mixture was washed with ethanol and dried at room temperature for 12 h to obtain Mo. 72 V 30 Crystal.

[0021] (2) Add nickel foam (1*1 cm) 2The sample was placed in a beaker and ultrasonically treated sequentially in acetone and concentrated hydrochloric acid solutions for 30 min each. It was then ultrasonically cleaned with anhydrous ethanol and deionized water, and dehydrated overnight under vacuum at 60°C. 98 mg of ammonium fluoride, 200 mg of urea, and 194 mg of nickel nitrate hexahydrate were dissolved in 12 mL of deionized water. A pre-treated nickel foam substrate was placed in the solution. The reaction vessel containing the solution was placed in an oven at 120°C for 10 h, then slowly cooled to room temperature. The product was collected, washed several times with distilled water, and then processed in a tube furnace at 500°C under N2 atmosphere to obtain a NiO nanorod array (NF-MO heterostructure). The 30 min ultrasonic treatment after adding acetone was to remove surface oil, the 30 min ultrasonic treatment after adding hydrochloric acid was to remove the surface oxide layer, and the ultrasonic treatment in anhydrous ethanol and deionized water was to remove any adsorbed ions.

[0022] (3) Add 0.11 mg Mo 72 V 30 0.22 mg of thiourea was dissolved in 10 mL of deionized water and stirred for 30 min. The solution was then transferred to a 20 mL hydrothermal reactor. A pre-made NF-MO template (2) was immersed in the reaction solution. The reactor was kept at 180°C for 12 h in a temperature-controlled oven and then naturally cooled to room temperature to obtain vanadium-doped nickel-molybdenum sulfide V-MoS2 / Ni3S2@NF-MO loaded on nickel foam. The nanoparticles formed flower-like clusters that uniformly covered the surface of nickel foam. Attached Figure Description

[0023] like Figure 1 The image shows the XRD pattern of a nickel-molybdenum sulfide supported on a nickel foam with a polyacid-derived flower-like vanadium doped structure. The figure shows the characteristic peak of Ni3S2 (PDF, No. 76-1870) and the characteristic peak of CoS2 (JCPDS, No. 65-3322), which proves the successful preparation of the target material.

[0024] like Figure 2 The image shows scanning electron microscope (SEM) images of a nickel foam supported on a polyacid-derived vanadium-doped nickel-molybdenum sulfide at different sizes. Uniform Ni3S2 and MoS2 nanosheet structures can be observed on the surface of the nickel foam.

[0025] like Figure 3 The image shown is a high-resolution transmission electron microscope image of a nickel-molybdenum sulfide doped with polyacid-derived flower-like vanadium supported on nickel foam. Clear lattice fringes and close contact between Ni3S2(111) and MoS2(100) can be observed, which further confirms the formation of the heterojunction.

[0026] like Figure 4The figure shows the hydrogen evolution polarization curve of a vanadium-doped polyacid-derived vanadium-doped nickel-molybdenum sulfide supported on nickel foam in an alkaline electrolyte solution. It can be observed that at a current density of 10 mA·cm⁻¹... -2 At that time, the overpotential of the electrode material was 25 mV.

[0027] like Figure 5 The image shows an electrochemical active area plot of a vanadium-doped polyacid-derived flower-like vanadium-doped nickel-molybdenum sulfide supported on nickel foam and other commercial catalysts. The image indicates that V-MoS2 / Ni3S2@NF-MO exhibits the lowest charge transfer resistance and more active sites participating in the reaction. The formation of the heterostructure can accelerate electron transfer to the active sites, and the surface hydroxyl groups (OH-) - Rapid desorption reduces interface clogging.

[0028] like Figure 6 The image shows a vanadium-doped polyacid-derived flower-like vanadium-doped nickel-molybdenum sulfide supported on nickel foam at 10 mA·cm⁻¹. -2 The stability diagram of V-MoS2 / Ni3S2@NF-MO after 100 h of stable operation at a current density is shown in the figure, which demonstrates the upper-level stability of V-MoS2 / Ni3S2@NF-MO.

Claims

1. A method for preparing a nickel-molybdenum sulfide supported on nickel foam and doped with polyacid-derived vanadium clusters, the method comprising the following steps: (1) 2.6 g NaVO3 was added to 55 mL of distilled water at 60℃, and 6 g Na2MoO4·2H2O was added to 75 mL of distilled water. Both solutions were stirred for 15 min each and labeled as solution A and solution B, respectively. After solution A cooled to room temperature, the two solutions were mixed and stirred for 15 min. 20 mL of H2SO4 solution was added to the solution and stirred for 15 min. Then 0.9 g of N2H4·H2SO4 was added and stirred for 3 h. Subsequently, 20 mL of KCl solution was added and stirred for 5 min. The mixture was then transferred to an Erlenmeyer flask and left open at room temperature for 4 days. After filtration, the mixture was washed with ethanol and dried at room temperature for 12 h to obtain Mo. 72 V 30 Crystals; (2) Add nickel foam (1*1 cm) 2 The sample was placed in a beaker and ultrasonically treated in acetone and concentrated hydrochloric acid solutions for 30 min, then ultrasonically cleaned with anhydrous ethanol and deionized water, and dehydrated overnight under vacuum at 60°C. 98 mg of ammonium fluoride, 200 mg of urea and 194 mg of nickel nitrate hexahydrate were dissolved in 12 mL of deionized water, and a pretreated nickel foam substrate was placed in the solution. The reaction vessel containing the solution was placed in an oven at 120°C for 10 h, and then slowly cooled to room temperature to collect the product. The product was washed several times with distilled water and then obtained in a tube furnace at 500°C under N2 atmosphere to obtain NiO nanorod arrays (NF-MO heterostructures). (3) Add 0.11 mg Mo 72 V 30 0.22 mg of thiourea was dissolved in 10 mL of deionized water and stirred for 30 min. The solution was then transferred to a 20 mL hydrothermal reactor. A pre-made NF-MO template (2) was immersed in the reaction solution. The reactor was kept at 180°C for 12 h in a temperature-controlled oven and then naturally cooled to room temperature to obtain vanadium-doped nickel-molybdenum sulfide V-MoS2 / Ni3S2@NF-MO supported on nickel foam.

2. The application of a foamed nickel-supported polyacid-derived vanadium-doped nickel-molybdenum sulfide prepared by the method of claim 1, characterized in that, A nickel-molybdenum sulfide supported on nickel foam and doped with polyacid-derived vanadium clusters is applied to the field of electrocatalytic water splitting for hydrogen production.

3. The application of the nickel foam-supported polyacid-derived vanadium-doped nickel-molybdenum sulfide according to claim 1, characterized in that, The application method is as follows: Using a 1.0 mol / L potassium hydroxide aqueous solution as the electrolyte, the nickel foam-supported polyacid-derived vanadium-doped nickel-molybdenum sulfide is used as the working electrode, a saturated calomel electrode as the reference electrode, and a carbon rod electrode as the counter electrode. In an alkaline electrolyte solution, when the overpotential is 25 mV, the current density is 10 mA·cm⁻¹. -2 It remained stable even after 100 hours of operation.

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