Preparation method of self-leaching / assembled nickel-tungsten alloy composite material and application of self-leaching / assembled nickel-tungsten alloy composite material in producing hydrogen by electrolyzing water

Abstract

The invention belongs to the technical field of electrochemistry, and relates to a preparation method of a self-leaching / assembled nickel-tungsten alloy composite material, which comprises the following steps: preparing nickel nitrate hexahydrate, ammonium metatungstate and deionized water into a solution, transferring the solution and a pretreated base material into a stainless steel autoclave with a Teflon lining, carrying out hydrothermal reaction, and cleaning to obtain a nano precursor NiWO-Sub; carrying out reduction heat treatment under the protection of a hydrogen-containing atmosphere to obtain a tungsten composite precursor Ni-WO-Comp; and performing electrochemical activation treatment by adopting a cyclic voltammetry method. Through a self-leaching-assembling strategy, controllable leaching of a tungsten element and in-situ optimized assembling of a material structure are achieved in the electrochemical activation process, the formed amorphous WOx and W-doped NiW alloy composite structure is balanced under the high-concentration W leaching effect, continuous tungsten leaching in an industrial-grade electrolyzed water environment is effectively inhibited, and the yield of the tungsten-doped WOx and W-doped NiW alloy composite structure is improved. And the long-term catalytic stability of the nickel-tungsten alloy electrode is obviously improved. And the preparation process is simple and easy to implement, can be attached to various different substrates, and is easy to implement industrially.

Description

Technical Field

[0001] The present invention belongs to the field of electrochemical technology and relates to the preparation of hydrolysis electrode materials, in particular to a preparation method of a self-leaching / assembly type nickel-tungsten alloy composite material and its application in hydrogen production by electrolysis of water. Background Art

[0002] As the simplest and most effective method for obtaining high-purity hydrogen, water electrolysis is highly dependent on high-performance electrocatalysts. The hydrogen evolution reaction (HER) in alkaline water electrolysis is a mature method for industrial hydrogen production due to its low device construction cost and the availability of a variety of high-performance catalysts. Nickel-tungsten alloy, as one of the most advanced materials, even outperforms commercial Pt / C (Dual Active Site Engineering in Porous NiW Bimetallic Alloys for Enhanced Alkaline Hydrogen Evolution Reaction. Adv. Mater., 2025: 2503742.; Surface structure evolution of bimetallic nickel tungsten nitride (Ni2W3N) forhigh performance hydrogen evolution. J. Mater. Chem. A, 2025, 13(6): 4404-4412.). In the structure of nickel-tungsten alloy, tungsten atoms serve as active sites for water dissociation. By adjusting the electronic state of the phase boundary, the energy barrier of the water dissociation step is reduced, and the adsorption / desorption characteristics of intermediates on the nickel site during the alkaline HER process are optimized. However, metallic tungsten is easily leached in alkaline environments, resulting in poor catalytic stability. Therefore, reducing the adverse effects of the solubility of metallic tungsten on catalytic performance is the key to the rational design of high-performance nickel-tungsten alloy materials.

[0003] So far, surface modification of amorphous WO x Or W atom doping is a common method to construct high performance nickel-tungsten alloy materials. x Modified Ni4W alloys and PtNi nanowires, Ni2W1 alloys, etc., by optimizing the d-band center of the W 5d orbital, enhance the desorption of *OH intermediates, promote the adsorption and dissociation of H2O at the W site, and thus improve the HER activity of the composite material. However, this conclusion is highly dependent on the stable catalytic structure during the HER process. The inevitable W leaching process leads to unstable catalytic structure and catalytic activity as well as a complex structure-activity relationship. In addition, the industrial-grade electrolytic water environment tends to accelerate the leaching rate of W, thereby destroying the structural stability and catalytic activity of the catalytic material. "Surface modification of amorphous WOx The limitation of the "doping with W atoms" strategy is that it cannot cope with the accelerated effect of industrial-grade electrolyzed water on W leaching, resulting in structural instability, activity decay, and complex structure-activity relationship.

[0004] Therefore, developing a new strategy that can actively utilize and control the high-concentration W leaching process and achieve a dynamic balance between leaching and in-situ assembly of the structure is the key to preparing a high-efficiency, high-stability nickel-tungsten alloy hydrogen evolution electrocatalyst suitable for industrial-grade water electrolysis environment. As far as the applicant knows, there is currently no public report on the construction of a high-efficiency, high-stability nickel-tungsten alloy hydrogen evolution electrocatalyst by achieving a leaching / assembly balance with a high-concentration W leaching rate. It can be foreseen that combining the high HER activity of nickel-tungsten alloy and the high-concentration leaching rate characteristics of bulk metal tungsten oxide, the use of a self-leaching / assembly strategy to construct a nickel-tungsten alloy composite material is a promising way to improve its industrial-grade water electrolysis hydrogen production activity and stability.

[0005] To date, there has been no research published on the preparation of self-leaching / assembly-type nickel-tungsten alloy composite electrodes and their application in industrial-grade water electrolysis to produce hydrogen under alkaline conditions. Summary of the Invention

[0006] In view of the defects of the prior art nickel-tungsten alloy materials in the alkaline electrolysis environment, which are structural instability and catalytic activity attenuation due to tungsten leaching, one object of the present invention is to disclose a self-leaching / assembly type nickel-tungsten alloy (WO 2 x -NiW) composite material preparation method.

[0007] Technical Solution

[0008] A method for preparing a self-leaching / assembly type nickel-tungsten alloy composite material comprises the following steps:

[0009] A. nickel nitrate hexahydrate, ammonium metatungstate and deionized water are mixed in a molar-volume ratio of 0.1-10 mmol:0.05-1 mmol:10-100 mL, preferably a molar-volume ratio of 1.8 mmol:0.45 mmol:30 mL, and stirred to form a solution;

[0010] B. Transfer the solution and the pretreated substrate to a Teflon-lined stainless steel autoclave, hydroheat at 150-200°C for 6-24 hours, preferably at 180°C for 18 hours, cool to room temperature, wash the precipitate thoroughly with deionized water and ethanol, and dry at 60°C for 6 hours to obtain the nano-precursor NiWO-Sub;

[0011] C. The nano-precursor NiWO-Sub is transferred to an open porcelain boat, a hydrogen-containing mixed gas is introduced, and the boat is transferred to a programmed temperature tubular furnace for reduction heat treatment at 400-600°C for 1-60 minutes, preferably at 500°C for 1 minute, under a hydrogen-containing atmosphere. After cooling naturally to room temperature, the boat is taken out to obtain the nickel-tungsten composite precursor Ni-WO-Comp.

[0012] D. The prepared nickel-tungsten composite precursor Ni-WO-Comp was immersed in a 1 mol / L KOH solution as an electrolyte for 5 minutes. Then, cyclic voltammetry (CV) was used for electrochemical activation in a potential window of -0.8 to -1.1 V with mercuric oxide as the reference electrode to induce the selective leaching of tungsten elements and simultaneously achieve in-situ assembly optimization of the material structure for 100 to 500 cycles, preferably 200 cycles. The material was thoroughly rinsed with deionized water and allowed to dry naturally to obtain a self-leaching / assembly type nickel-tungsten alloy composite material.

[0013] In a preferred embodiment of the present invention, in step B, the substrate is carbon paper CP, carbon cloth CC, nickel foam NF, conductive glass FTO or stainless steel mesh SSM, preferably nickel foam NF; the size of the substrate is about 4 cm long and about 2 cm wide.

[0014] In a preferred embodiment of the present invention, in step B, the pretreatment is to ultrasonically clean the substrate with acetone, ethanol and deionized water in sequence to remove organic matter and other impurities on the surface.

[0015] According to a preferred embodiment of the present invention, in step C, the hydrogen-containing mixed gas is an H2 / N2 mixed gas or an H2 / Ar mixed gas containing 5% by volume of H2.

[0016] In a preferred embodiment of the present invention, in step C, the temperature-programmed tubular furnace has a heating rate of 10° C. / min.

[0017] The self-leaching / assembly type nickel-tungsten alloy composite material prepared by the present invention is a random nano-particle structure formed by the self-leaching and self-reorganization of Ni-WO-Comp nanowires.

[0018] Another object of the present invention is to apply the prepared self-leaching / assembly type nickel-tungsten alloy composite material to industrial-grade water electrolysis hydrogen production negative electrode materials.

[0019] The catalyst morphology and structure, and the element concentration of the liquid phase product were analyzed using X-ray diffractometer (XRD), Raman spectrometer (Raman), scanning electron microscope (SEM) and inductively coupled plasma spectroscopy / mass spectrometer (ICP-OES / MS). Electrocatalytic water decomposition and hydrogen evolution experiments were carried out using potassium hydroxide (KOH) solution as the target. The electrochemical polarization curve (LSV), cyclic voltammetry (CV) and stability test were analyzed to evaluate its electrocatalytic water decomposition and hydrogen evolution activity.

[0020] Electrocatalytic activity experiment of self-leaching / assembly type nickel-tungsten alloy composite material:

[0021] (1) Prepare a 1 mol / L KOH solution, seal it tightly and store it in a cool, dark place.

[0022] (2) The electrochemical performance of the samples was tested in a three-electrode system using CHI760E and CHI1140D electrochemical workstations (Shanghai Chenhua Instrument Co., Ltd.); a carbon rod was used as the counter electrode, a mercury oxide electrode (Hg / HgO) was used as the reference electrode, and the prepared composite materials and control samples (tungsten oxide, metallic nickel, and commercial Pt / C) were used as working electrodes. The fixed test area was 0.5 cm 2 The electrochemical properties of the electrode materials were tested by linear sweep voltammetry (LSV), cyclic voltammetry (CV) and chronopotentiometry (Pt) in 1 mol / L KOH electrolyte. The LSV test window potential was -0.8 to -1.8 V, with a scan rate of 5 mV / s; the CV activation window was -0.8 to -1.1 V, with a scan rate of 50 mV / s; the CV cycle double layer capacitance window was -0.8 to -0.9 V, with scan rates of 2, 4, 6, 8 and 10 mV / s; the stability test was performed by chronopotentiometry with constant current densities of -0.1, -0.5 and -1 A / cm 2 .

[0023] The self-leaching / assembly type nickel-tungsten alloy composite material prepared by the present invention is a nickel-tungsten composite precursor with tungsten oxide as the main phase and metal nickel as the auxiliary phase obtained after hydrothermal reaction calcination. The nickel-tungsten composite precursor Ni-WO-Comp has a nickel-tungsten atomic ratio of about 1:6. It is subjected to a CV cycle reaction in an alkaline solution for a period of time. The tungsten oxide as the main phase material undergoes a high concentration leaching and assembly optimization process of metal W, selectively generating a large amount of amorphous WO x The W-doped NiW alloy composite structure has a nickel-tungsten atomic ratio of about 6.4:1 in the self-leached / assembled nickel-tungsten alloy composite material obtained after electrochemical activation treatment; and compared with pure nickel, pure tungsten oxide and commercial Pt / C catalysts, it exhibits a lower overpotential for the electrocatalytic decomposition of water for hydrogen evolution reaction, as well as industrial-grade application prospects.

[0024] Beneficial effects

[0025] The present invention uses a unique "self-leaching-assembly" strategy to achieve controllable leaching of tungsten elements and in-situ optimized assembly of material structures during the electrochemical activation process. The high concentration of W leaching balances the formed amorphous WO x The composite structure of the W-doped NiW alloy effectively inhibits the continuous tungsten leaching in industrial-grade water electrolysis environments, thereby significantly improving the long-term catalytic stability of the nickel-tungsten alloy electrode. The preparation process is simple and easy, and it can be attached to a variety of substrates, making it easy to implement industrially. The resulting composite electrode maintains good catalytic activity and stability through its self-leaching / assembly properties. The raw materials are inexpensive and readily available, non-toxic, and the process is simple, making it suitable as an electrode for the electrocatalytic water splitting and hydrogen evolution reaction in industrial environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 (a) Prepared Ni-WO-Comp composite precursor and self-leaching / assembly WO x -NiW X-ray diffraction (XRD) spectrum; (b) prepared Ni-WO-Comp composite precursor and self-leached / assembled WO x -NiW local magnified X-ray diffraction (XRD) spectrum; the horizontal axis is the diffraction angle (2θ), the unit is degree (º), and the vertical axis is the intensity (Intensity), the unit is cps.

[0027] Figure 2 . Prepared Ni-WO-Comp composite precursor and self-leaching / assembly type WO x -NiW Raman spectrum; the horizontal axis is the Raman shift, the unit is wave number (cm -1 ), the vertical axis is intensity (Intensity), the unit is cps.

[0028] Figure 3 (a) is a scanning electron microscope (SEM) image of the prepared Ni-WO-Comp composite precursor; (b) is a self-leaching / assembly type WO x -NiW scanning electron microscope (SEM) image; (c) prepared Ni-WO-Comp composite precursor and self-leached / assembled WO x -Elemental energy spectrum corresponding to the scanning electron microscope (SEM) photograph of NiW.

[0029] Figure 4 . Self-leaching / assembly type WO x -NiW sample at a constant current density of -0.1A / cm 2 The concentration of W and Ni in the reaction solution changes with time.

[0030] Figure 5 .(a) Self-leaching / assembly type WO x Polarization curves of the electrocatalytic water decomposition and hydrogen evolution of the NiW sample, the control group Ni, WO and the commercial 20% Pt / C sample; (b) WO x -NiW samples at current densities of -0.1, -0.5 and -1 A / cm 2 Performance diagram of constant current test for 20h.

[0031] Figure 6 .(a) Self-leaching / assembly type WO x -NiW sample and the electrochemical double layer capacitance fitting diagram of the control group Ni, WO and commercial 20% Pt / C sample; (b) WO x -NiW sample cyclic voltammetry (CV) curves at different scan rates; (c) Ni sample cyclic voltammetry (CV) curves at different scan rates; (d) WO sample cyclic voltammetry (CV) curves at different scan rates; (e) 20% Pt / C sample cyclic voltammetry (CV) curves at different scan rates. DETAILED DESCRIPTION

[0032] The present invention will be described in detail below with reference to the following examples so that those skilled in the art can better understand the present invention. However, the present invention is not limited to the following examples.

[0033] Unless otherwise defined, the terms used herein (including technical and scientific terms) should be interpreted as having the same meaning as commonly understood by those skilled in the art to which the present invention belongs. It will also be understood that the terms used herein should be interpreted as having the meaning consistent with their meaning in the context of this specification and the related art, and should not be interpreted in an idealized or excessive manner unless specifically defined as such herein.

[0034] Example 1

[0035] Self-leaching / assembly type nickel-tungsten alloy composite material (WO x-NiW alloy (variable is the metal molar ratio Ni:W = 1:3 in the raw metal salt) was prepared by a hydrothermal-calcination method: 1.8mmol of nickel nitrate hexahydrate and 0.45mmol of ammonium metatungstate were weighed and dissolved in 30mL of deionized water with stirring; the above solution and a clean nickel foam (NF) (4cm×2cm) were transferred to a 50mL Teflon-lined stainless steel autoclave and placed at 180℃ for 18 hours. After cooling to room temperature, the sample was removed and thoroughly washed with deionized water and ethanol, and dried at 60℃ for 6 hours to obtain NiWO-Sub. NiWO-Sub was reduced at a temperature of 500℃, a heating rate of 10℃ / min, and a reduction time of 1 minute in an H2 / Ar (5:95) or H2 / N2 (5:95) atmosphere to obtain a Ni-WO-Comp composite precursor.

[0036] like Figure 1-3 As shown, Ni-WO-Comp is WO 2.72 The composite crystal structure of Ni and W shows a smooth nanowire morphology. The ratio of each element is shown in the table below, where the atomic ratio of Ni to W is about 1:6. The prepared Ni-WO-Comp is fixed to a test area of 0.5 cm 2 , the electrolyte was 1mol / L KOH solution, first soaked for 5min, then CV cycled 200 times in the potential window of -0.8~-1.1V, the prepared self-leaching / assembly type nickel-tungsten alloy composite electrode was fully rinsed with deionized water and dried naturally to obtain WO x -NiW / NF sample. By comparison, it was found that WO x -NiW in WO 2.72 The main crystal plane disappears and turns into amorphous WO x , and part of the W element is optimized into the metal Ni structure to form NiW alloy, while the large amount of W leaching transforms the nanowire structure into nanoparticles ( Figure 3 and 4 ). At this time, the atomic ratio of Ni and W in the material is about 6.4:1.

[0037] Table 1 shows the prepared Ni-WO-Comp composite precursor and self-leaching / assembly WO x -The atomic ratio of elements corresponding to the scanning electron microscope (SEM) image of NiW.

[0038] Table 1

[0039] element Ni-WO-comp (At%) <![CDATA[WO x -NiW (Ar%)]]> O 54.03 59.64 Ni 6.55 34.94 W 39.42 5.42 Total 100.00 100.00

[0040] Prepared WO x -NiW / NF samples were tested at current densities of -0.02, -0.1, and -0.5 A / cm 2The overpotentials can reach 28, 82 and 244 mV respectively.

[0041] Example 2

[0042] Self-leaching / assembly type nickel-tungsten alloy composite material (WO x -NiW alloy, the variable is the metal molar ratio Ni:W=1:1 in the raw metal salt) is prepared by the hydrothermal-calcination method: 3.6mmol of nickel nitrate hexahydrate and 0.3mmol of ammonium metatungstate are weighed and dissolved in 30mL of deionized water and stirred to dissolve; the above solution and a clean nickel foam (NF) (4cm×2cm) are transferred to a 50mL Teflon-lined stainless steel autoclave and placed at 180℃ for 18h. After cooling to room temperature, the sample is taken out and thoroughly washed with deionized water and ethanol, and dried at 60℃ for 6h to obtain NiWO-Sub; NiWO-Sub is reduced at a temperature of 500℃, a heating rate of 10℃ / min, and a reduction time of 1min in an atmosphere of H2 / Ar (5:95) or H2 / N2 (5:95) to obtain a Ni-WO-Comp composite precursor. The prepared Ni-WO-Comp is fixed to a test area of 0.5cm 2 , the electrolyte was 1mol / L KOH solution, first soaked for 5min, then CV cycled 200 times in the potential window of -0.8~-1.1V, the prepared self-leaching / assembly type nickel-tungsten alloy composite electrode was fully rinsed with deionized water and dried naturally to obtain WO x -NiW / NF samples.

[0043] Prepared WO x -NiW / NF samples were tested at current densities of -0.02, -0.1, and -0.5 A / cm 2 The overpotentials can reach 32, 93 and 261 mV respectively.

[0044] Example 3

[0045] Self-leaching / assembly type nickel-tungsten alloy composite material (WO x-NiW alloy, the variable is the metal molar ratio Ni:W=3:1 in the raw metal salt) is prepared by a hydrothermal-calcination method: 5.4mmol of nickel nitrate hexahydrate and 0.15mmol of ammonium metatungstate are weighed and dissolved in 30mL of deionized water and stirred to dissolve; the above solution and a clean nickel foam (NF) (4cm×2cm) are transferred to a 50mL Teflon-lined stainless steel autoclave and placed at 180℃ for 18h. After cooling to room temperature, the sample is taken out and thoroughly washed with deionized water and ethanol, and dried in a 60℃ forced air drying oven for 6h to obtain NiWO-Sub; NiWO-Sub is reduced at a temperature of 500℃, a heating rate of 10℃ / min, and a reduction time of 1min in an atmosphere of H2 / Ar (5:95) or H2 / N2 (5:95) to obtain a Ni-WO-Comp composite precursor. The prepared Ni-WO-Comp is fixed to a test area of 0.5cm 2 , the electrolyte was 1mol / L KOH solution, first soaked for 5min, then CV cycled 200 times in the potential window of -0.8~-1.1V, the prepared self-leaching / assembly type nickel-tungsten alloy composite electrode was fully rinsed with deionized water and dried naturally to obtain WO x -NiW / NF samples.

[0046] Prepared WO x -NiW / NF samples were tested at current densities of -0.02, -0.1, and -0.5 A / cm 2 The overpotentials can reach 44, 116 and 291 mV respectively.

[0047] Example 4

[0048] Self-leaching / assembly type nickel-tungsten alloy composite material (WO x -NiW alloy, the variable is the metal molar ratio Ni:W=1:7 in the raw metal salt) is prepared by the hydrothermal-calcination method: 0.9mmol nickel nitrate hexahydrate and 0.525mmol ammonium metatungstate are weighed and dissolved in 30mL deionized water and stirred to dissolve; the above solution and a clean nickel foam (NF) (4cm×2cm) are transferred to a 50mL Teflon-lined stainless steel autoclave and placed at 180℃ for 18h. After cooling to room temperature, the sample is taken out and thoroughly washed with deionized water and ethanol, and dried at 60℃ for 6h to obtain NiWO-Sub; NiWO-Sub is reduced at a temperature of 500℃, a heating rate of 10℃ / min, and a reduction time of 1min in an atmosphere of H2 / Ar (5:95) or H2 / N2 (5:95) to obtain a Ni-WO-Comp composite precursor. The prepared Ni-WO-Comp is fixed to a test area of 0.5cm 2, the electrolyte was 1mol / LKOH solution, first soaked for 5min, then CV cycled 200 times in the potential window of -0.8~-1.1V, the prepared self-leaching / assembly type nickel-tungsten alloy composite electrode was fully rinsed with deionized water and dried naturally to obtain WO x -NiW / NF samples.

[0049] Prepared WO x -NiW / NF samples were tested at current densities of -0.02, -0.1, and -0.5 A / cm 2 The overpotentials can reach 34, 95 and 281 mV respectively.

[0050] Example 5

[0051] Self-leaching / assembly type nickel-tungsten alloy composite material (WO x -NiW alloy, the variable is the metal molar ratio Ni:W=1:39 in the raw metal salt) is prepared by the hydrothermal-calcination method: 0.18mmol nickel nitrate hexahydrate and 0.585mmol ammonium metatungstate are weighed and dissolved in 30mL deionized water and stirred to dissolve; the above solution and a clean nickel foam (NF) (4cm×2cm) are transferred to a 50mL Teflon-lined stainless steel autoclave and placed at 180℃ for 18h. After cooling to room temperature, the sample is taken out and thoroughly washed with deionized water and ethanol, and dried at 60℃ for 6h to obtain NiWO-Sub; NiWO-Sub is reduced at a temperature of 500℃, a heating rate of 10℃ / min, and a reduction time of 1min in an atmosphere of H2 / Ar (5:95) or H2 / N2 (5:95) to obtain a Ni-WO-Comp composite precursor. The prepared Ni-WO-Comp is fixed to a test area of 0.5cm 2 , the electrolyte was 1mol / L KOH solution, first soaked for 5min, then CV cycled 200 times in the potential window of -0.8~-1.1V, the prepared self-leaching / assembly type nickel-tungsten alloy composite electrode was fully rinsed with deionized water and dried naturally to obtain WO x -NiW / NF samples.

[0052] Prepared WO x -NiW / NF samples were tested at current densities of -0.02, -0.1, and -0.5 A / cm 2 The overpotentials can reach 56, 199 and 413 mV respectively.

[0053] Example 6

[0054] Self-leaching / assembly type nickel-tungsten alloy composite material (WO x-NiW alloy, the variable is the reactor temperature of 160℃) is prepared by the hydrothermal-calcination method: 1.8mmol nickel nitrate hexahydrate and 0.45mmol ammonium metatungstate are weighed and dissolved in 30mL deionized water and stirred to dissolve; the above solution and a clean nickel foam (NF) (4cm×2cm) are transferred to a 50mL Teflon-lined stainless steel autoclave, placed at 160℃ for 18h, and cooled to room temperature; the sample is taken out and thoroughly washed with deionized water and ethanol, and dried at 60℃ for 6h to obtain NiWO-Sub; NiWO-Sub is reduced at a temperature of 500℃, a heating rate of 10℃ / min, and a reduction time of 1min in an atmosphere of H2 / Ar (5:95) or H2 / N2 (5:95) to obtain a Ni-WO-Comp composite precursor. The prepared Ni-WO-Comp is fixed to a test area of 0.5cm 2 , the electrolyte was 1mol / L KOH solution, first soaked for 5min, then CV cycled 200 times in the potential window of -0.8~-1.1V, the prepared self-leaching / assembly type nickel-tungsten alloy composite electrode was fully rinsed with deionized water and dried naturally to obtain WO x -NiW / NF samples.

[0055] Prepared WO x -NiW / NF samples were tested at current densities of -0.02, -0.1, and -0.5 A / cm 2 The overpotential can reach 35, 88 and 250 mV respectively.

[0056] Example 7

[0057] Self-leaching / assembly type nickel-tungsten alloy composite material (WO x -NiW alloy, the variable is the reactor temperature of 200℃) is prepared by the hydrothermal-calcination method: 1.8mmol nickel nitrate hexahydrate and 0.45mmol ammonium metatungstate are weighed and dissolved in 30mL deionized water and stirred to dissolve; the above solution and a clean nickel foam (NF) (4cm×2cm) are transferred to a 50mL Teflon-lined stainless steel autoclave, placed at 200℃ for 18h, and cooled to room temperature; the sample is taken out and thoroughly washed with deionized water and ethanol, and dried at 60℃ for 6h to obtain NiWO-Sub; NiWO-Sub is reduced at a temperature of 500℃, a heating rate of 10℃ / min, and a reduction time of 1min in an atmosphere of H2 / Ar (5:95) or H2 / N2 (5:95) to obtain a Ni-WO-Comp composite precursor. The prepared Ni-WO-Comp is fixed to a test area of 0.5cm 2, the electrolyte was 1mol / L KOH solution, first soaked for 5min, then CV cycled 200 times in the potential window of -0.8~-1.1V, the prepared self-leaching / assembly type nickel-tungsten alloy composite electrode was fully rinsed with deionized water and dried naturally to obtain WO x -NiW / NF samples.

[0058] Prepared WO x -NiW / NF samples were tested at current densities of -0.02, -0.1, and -0.5 A / cm 2 The overpotential can reach 55, 160 and 360 mV respectively.

[0059] Example 8

[0060] Self-leaching / assembly type nickel-tungsten alloy composite material (WO x -NiW alloy, the variable is the hydrothermal time in the reactor for 15h) was prepared by the hydrothermal-calcination method: 1.8mmol nickel nitrate hexahydrate and 0.45mmol ammonium metatungstate were weighed and dissolved in 30mL deionized water and stirred to dissolve; the above solution and a clean nickel foam (NF) (4cm×2cm) were transferred to a 50mL Teflon-lined stainless steel autoclave and placed at 180℃ for 6h. After cooling to room temperature, the sample was taken out and thoroughly washed with deionized water and ethanol, and dried at 60℃ for 6h to obtain NiWO-Sub; NiWO-Sub was reduced at a temperature of 500℃, a heating rate of 10℃ / min, and a reduction time of 1min in an atmosphere of H2 / Ar (5:95) or H2 / N2 (5:95) to obtain a Ni-WO-Comp composite precursor. The prepared Ni-WO-Comp was fixed to a test area of 0.5cm 2 , the electrolyte was 1mol / L KOH solution, first soaked for 5min, then CV cycled 200 times in the potential window of -0.8~-1.1V, the prepared self-leaching / assembly type nickel-tungsten alloy composite electrode was fully rinsed with deionized water and dried naturally to obtain WO x -NiW / NF samples.

[0061] Prepared WO x -NiW / NF samples were tested at current densities of -0.02, -0.1, and -0.5 A / cm 2 The overpotentials can reach 33, 104 and 282 mV respectively.

[0062] Example 9

[0063] Self-leaching / assembly type nickel-tungsten alloy composite material (WO x-NiW alloy, the variable is the hydrothermal time in the reactor for 21h) was prepared by the hydrothermal-calcination method: 1.8mmol nickel nitrate hexahydrate and 0.45mmol ammonium metatungstate were weighed and dissolved in 30mL deionized water and stirred to dissolve; the above solution and a clean nickel foam (NF) (4cm×2cm) were transferred to a 50mL Teflon-lined stainless steel autoclave and placed at 180℃ for 12h. After cooling to room temperature, the sample was taken out and thoroughly washed with deionized water and ethanol, and dried at 60℃ for 6h to obtain NiWO-Sub; NiWO-Sub was reduced at a temperature of 500℃, a heating rate of 10℃ / min, and a reduction time of 1min in an atmosphere of H2 / Ar (5:95) or H2 / N2 (5:95) to obtain a Ni-WO-Comp composite precursor. The prepared Ni-WO-Comp was fixed to a test area of 0.5cm 2 , the electrolyte was 1mol / L KOH solution, first soaked for 5min, then CV cycled 200 times in the potential window of -0.8~-1.1V, the prepared self-leaching / assembly type nickel-tungsten alloy composite electrode was fully rinsed with deionized water and dried naturally to obtain WO x -NiW / NF samples.

[0064] Prepared WO x -NiW / NF samples were tested at current densities of -0.02, -0.1, and -0.5 A / cm 2 The overpotential can reach 37, 106 and 306 mV respectively.

[0065] Example 10

[0066] Self-leaching / assembly type nickel-tungsten alloy composite material (WO x -NiW alloy, the variable is the calcination temperature of 400℃) is prepared by the hydrothermal-calcination method: 1.8mmol nickel nitrate hexahydrate and 0.45mmol ammonium metatungstate are weighed and dissolved in 30mL deionized water and stirred to dissolve; the above solution and a clean nickel foam (NF) (4cm×2cm) are transferred to a 50mL Teflon-lined stainless steel autoclave, placed at 180℃ for 18h, and cooled to room temperature; the sample is taken out and thoroughly washed with deionized water and ethanol, and dried at 60℃ for 6h to obtain NiWO-Sub; NiWO-Sub is reduced at 400℃, a heating rate of 10℃ / min, and a reduction time of 1min in H2 / Ar (5:95) or H2 / N2 (5:95) atmosphere to obtain a Ni-WO-Comp composite precursor. The prepared Ni-WO-Comp is fixed to a test area of 0.5cm 2, the electrolyte was 1mol / L KOH solution, first soaked for 5min, then CV cycled 200 times in the potential window of -0.8~-1.1V, the prepared self-leaching / assembly type nickel-tungsten alloy composite electrode was fully rinsed with deionized water and dried naturally to obtain WO x -NiW / NF samples.

[0067] Prepared WO x -NiW / NF samples were tested at current densities of -0.02, -0.1, and -0.5 A / cm 2 The overpotentials can reach 195, 326 and 488 mV respectively.

[0068] Example 11

[0069] Self-leaching / assembly type nickel-tungsten alloy composite material (WO x -NiW alloy, the variable is the calcination temperature of 600℃) is prepared by the hydrothermal-calcination method: 1.8mmol nickel nitrate hexahydrate and 0.45mmol ammonium metatungstate are weighed and dissolved in 30mL deionized water and stirred to dissolve; the above solution and a clean nickel foam (NF) (4cm×2cm) are transferred to a 50mL Teflon-lined stainless steel autoclave, placed at 180℃ for 18h, and cooled to room temperature; the sample is taken out and thoroughly washed with deionized water and ethanol, and dried at 60℃ for 6h to obtain NiWO-Sub; NiWO-Sub is reduced at a temperature of 600℃, a heating rate of 10℃ / min, and a reduction time of 1min in an atmosphere of H2 / Ar (5:95) or H2 / N2 (5:95) to obtain a Ni-WO-Comp composite precursor. The prepared Ni-WO-Comp is fixed to a test area of 0.5cm 2 , the electrolyte was 1mol / L KOH solution, first soaked for 5min, then CV cycled 200 times in the potential window of -0.8~-1.1V, the prepared self-leaching / assembly type nickel-tungsten alloy composite electrode was fully rinsed with deionized water and dried naturally to obtain WO x -NiW / NF samples.

[0070] Prepared WO x -NiW / NF samples were tested at current densities of -0.02, -0.1, and -0.5 A / cm 2 The overpotentials can reach 31, 119 and 284 mV respectively.

[0071] Example 12

[0072] Self-leaching / assembly type nickel-tungsten alloy composite material (WO x-NiW alloy, the variable is calcination time 30min) is prepared by the hydrothermal-calcination method: weigh 1.8mmol nickel nitrate hexahydrate and 0.45mmol ammonium metatungstate and dissolve them in 30mL deionized water and stir to dissolve; the above solution and a clean nickel foam (NF) (4cm×2cm) are transferred to a 50mL Teflon-lined stainless steel autoclave and placed at 180℃ for 18h. After cooling to room temperature, the sample is taken out and thoroughly washed with deionized water and ethanol, and dried at 60℃ for 6h to obtain NiWO-Sub; NiWO-Sub is reduced at a temperature of 500℃, a heating rate of 10℃ / min, and a reduction time of 30min in an atmosphere of H2 / Ar (5:95) or H2 / N2 (5:95) to obtain a Ni-WO-Comp composite precursor. The prepared Ni-WO-Comp is fixed to a test area of 0.5cm 2 , the electrolyte was 1mol / L KOH solution, first soaked for 5min, then CV cycled 200 times in the potential window of -0.8~-1.1V, the prepared self-leaching / assembly type nickel-tungsten alloy composite electrode was fully rinsed with deionized water and dried naturally to obtain WO x -NiW / NF samples.

[0073] Prepared WO x -NiW / NF samples were tested at current densities of -0.02, -0.1, and -0.5 A / cm 2 The overpotentials can reach 30, 100 and 276 mV respectively.

[0074] Example 13

[0075] Self-leaching / assembly type nickel-tungsten alloy composite material (WO x -NiW alloy, the variable is calcination time 60min) is prepared by the hydrothermal-calcination method: weigh 1.8mmol nickel nitrate hexahydrate and 0.45mmol ammonium metatungstate and dissolve them in 30mL deionized water and stir to dissolve; the above solution and a clean nickel foam (NF) (4cm×2cm) are transferred to a 50mL Teflon-lined stainless steel autoclave and placed at 180℃ for 18h. After cooling to room temperature, the sample is taken out and thoroughly washed with deionized water and ethanol, and dried at 60℃ for 6h to obtain NiWO-Sub; NiWO-Sub is reduced at a temperature of 500℃, a heating rate of 10℃ / min, and a reduction time of 60min in an atmosphere of H2 / Ar (5:95) or H2 / N2 (5:95) to obtain a Ni-WO-Comp composite precursor. The prepared Ni-WO-Comp is fixed to a test area of 0.5cm 2, the electrolyte was 1mol / L KOH solution, first soaked for 5min, then CV cycled 200 times in the potential window of -0.8~-1.1V, the prepared self-leaching / assembly type nickel-tungsten alloy composite electrode was fully rinsed with deionized water and dried naturally to obtain WO x -NiW / NF samples.

[0076] Prepared WO x -NiW / NF samples were tested at current densities of -0.02, -0.1, and -0.5 A / cm 2 The overpotentials can reach 36, 103 and 275 mV respectively.

[0077] Example 14

[0078] Self-leaching / assembly type nickel-tungsten alloy composite material (WO x -NiW alloy, variable is CV cycle 100 rounds) is prepared by hydrothermal-calcination method: weigh 1.8mmol nickel nitrate hexahydrate and 0.45mmol ammonium metatungstate and dissolve them in 30mL deionized water and stir to dissolve; the above solution and a clean nickel foam (NF) (4cm×2cm) are transferred to a 50mL Teflon-lined stainless steel autoclave and placed at 180℃ for 18h. After cooling to room temperature, the sample is taken out and thoroughly washed with deionized water and ethanol, and dried at 60℃ for 6h to obtain NiWO-Sub; NiWO-Sub is reduced at 500℃, heating rate of 10℃ / min and reduction time of 1min in H2 / Ar (5:95) or H2 / N2 (5:95) atmosphere to obtain Ni-WO-Comp composite precursor. The prepared Ni-WO-Comp is fixed to a test area of 0.5cm 2 , the electrolyte was 1mol / L KOH solution, first soaked for 5min, then CV cycled 100 times in the potential window of -0.8~-1.1V, the prepared self-leaching / assembly type nickel-tungsten alloy composite electrode was fully rinsed with deionized water and dried naturally to obtain WO x -NiW / NF samples.

[0079] Prepared WO x -NiW / NF samples were tested at current densities of -0.02, -0.1, and -0.5 A / cm 2 The overpotential can reach 30, 92 and 255 mV respectively.

[0080] Example 15

[0081] Self-leaching / assembly type nickel-tungsten alloy composite material (WO x-NiW alloy, variable is CV cycle 500 rounds) is prepared by hydrothermal-calcination method: weigh 1.8mmol nickel nitrate hexahydrate and 0.45mmol ammonium metatungstate and dissolve them in 30mL deionized water and stir to dissolve; the above solution and a clean nickel foam (NF) (4cm×2cm) are transferred to a 50mL Teflon-lined stainless steel autoclave and placed at 180℃ for 18h. After cooling to room temperature, the sample is taken out and thoroughly washed with deionized water and ethanol, and dried at 60℃ for 6h to obtain NiWO-Sub; NiWO-Sub is reduced at 500℃, heating rate of 10℃ / min and reduction time of 1min in H2 / Ar (5:95) or H2 / N2 (5:95) atmosphere to obtain Ni-WO-Comp composite precursor. The prepared Ni-WO-Comp is fixed to a test area of 0.5cm 2 , the electrolyte was 1mol / L KOH solution, first soaked for 5min, then CV cycled 500 times in the potential window of -0.8~-1.1V, the prepared self-leaching / assembly type nickel-tungsten alloy composite electrode was fully rinsed with deionized water and dried naturally to obtain WO x -NiW / NF samples.

[0082] Prepared WO x -NiW / NF samples were tested at current densities of -0.02, -0.1, and -0.5 A / cm 2 The overpotentials can reach 36, 93 and 272 mV respectively.

[0083] Based on the above examples, when the molar ratio of Ni:W in the raw material is 1:3 (Example 1), the hydrothermal temperature is 180℃ (Example 1), the hydrothermal time is 18h (Example 1), the heat treatment temperature is 500℃ (Example 1), the heat treatment time is 1min (Example 1), and the CV activation cycle is 200 cycles (Example 1), the prepared WO x -NiW exhibits the lowest overpotential and excellent industrial-grade current density stability in alkaline HER. Modifying these parameters, such as increasing or decreasing the W content (Examples 2-5), raising or lowering the hydrothermal / heat treatment temperature (Examples 6, 7, 10, or 11), and extending or shortening the hydrothermal / heat treatment / CV time (Examples 8, 9, 12-15), all lead to varying degrees of increased overpotential or decreased stability.

[0084] Combined with electrochemical test analysis, the self-leaching / assembly type nickel-tungsten alloy composite electrode prepared in the present invention exhibits excellent catalytic performance and stability. x -NiW is used as the negative electrode material for electrocatalytic water splitting ( Figure 5a) Compared with tungsten oxide (WO) and nickel (Ni), it shows a lower overpotential at a current density of -0.1A / cm 2 The overpotentials can reach 82mV, 266mV and 269mV respectively, which are even higher than commercial 20% Pt / C (157mV); WO x -NiW can also be -0.1A / cm 2 And industrial grade current density -0.5A / cm 2 and -1A / cm 2 The test under the current density for 20 hours still maintains good stability, and even has a trend of further improvement in performance ( Figure 5 b). Combined with double layer capacitance test ( Figure 6 ), the prepared WO x -NiW / NF shows a larger double layer capacitance (1.22mF / cm 2 ), indicating that WOx-NiW has a larger electrochemically active surface area and a larger number of catalytically active sites.

[0085] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the description of the present invention, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for preparing a self-leaching / assembly type nickel-tungsten alloy composite material, characterized in that: The steps include: A. Stir nickel nitrate hexahydrate, ammonium metatungstate, and deionized water in a molar-volume ratio of 0.1-10 mmol:0.05-1 mmol:10-100 mL to form a solution; B. The solution and pretreated substrate were transferred to a Teflon-lined stainless steel autoclave and hydroheated at 150-200°C for 6-24 hours. The mixture was cooled to room temperature, and the precipitate was washed thoroughly with deionized water and ethanol. The precipitate was dried at 60°C for 6 hours to obtain the nano-precursor NiWO-Sub. C. The nano-precursor NiWO-Sub is transferred to an open porcelain boat, a hydrogen-containing mixed gas is introduced, and the boat is transferred to a programmed temperature tubular furnace for reduction heat treatment at 400-600°C under a hydrogen-containing atmosphere for 1-60 minutes. After cooling naturally to room temperature, the boat is removed to obtain the nickel-tungsten composite precursor Ni-WO-Comp. D. The prepared nickel-tungsten composite precursor Ni-WO-Comp was immersed in a 1 mol / L KOH solution as an electrolyte for 5 minutes. Then, cyclic voltammetry (CV) was used for electrochemical activation in a potential window of -0.8 to -1.1 V with mercuric oxide as the reference electrode to induce the selective leaching of tungsten elements and simultaneously achieve in-situ assembly optimization of the material structure for 100 to 500 cycles, preferably 200 cycles. The material was thoroughly rinsed with deionized water and allowed to dry naturally.

2. The method for preparing the self-leaching / assembly type nickel-tungsten alloy composite material according to claim 1, wherein: In step A, the molar-volume ratio is 1.8 mmol:0.45 mmol:30 mL.

3. The method for preparing the self-leaching / assembly type nickel-tungsten alloy composite material according to claim 1, wherein: In step B, the solution and the pretreated substrate are transferred to a Teflon-lined stainless steel autoclave, hydroheated at 180° C. for 18 h, and cooled to room temperature.

4. The method for preparing the self-leaching / assembly type nickel-tungsten alloy composite material according to claim 1, wherein: In step B, the substrate is carbon paper CP, carbon cloth CC, nickel foam NF, conductive glass FTO or stainless steel mesh SSM; the size of the substrate is about 4 cm in length and about 2 cm in width.

5. The method for preparing the self-leaching / assembly type nickel-tungsten alloy composite material according to claim 1, wherein: In step B, the substrate is nickel foam NF.

6. The method for preparing the self-leaching / assembly type nickel-tungsten alloy composite material according to claim 1, wherein: In step B, the pretreatment is to ultrasonically clean the substrate with acetone, ethanol and deionized water in sequence to remove organic matter and other impurities on the surface.

7. The method for preparing the self-leaching / assembly type nickel-tungsten alloy composite material according to claim 1, wherein: In step C, the hydrogen-containing mixed gas is an H2 / N2 mixed gas or an H2 / Ar mixed gas containing 5% by volume of H2.

8. The method for preparing the self-leaching / assembly type nickel-tungsten alloy composite material according to claim 1, wherein: In step C, the nano precursor NiWO-Sub is transferred into an open porcelain boat, a hydrogen-containing mixed gas is introduced, and the nano precursor is transferred to a programmed temperature tubular furnace for reduction heat treatment at 500°C for 1 minute under a hydrogen-containing atmosphere; the programmed temperature tubular furnace has a heating rate of 10°C / min.

9. A self-leaching / assembly type nickel-tungsten alloy composite material prepared according to the method of any one of claims 1 to 8.

10. An application of the self-leaching / assembly type nickel-tungsten alloy composite material according to claim 9, characterized in that: It is applied to industrial-grade water electrolysis hydrogen production negative electrode materials.

Images