Preparation method and application of hydrogen evolution electrocatalyst with amorphous nickel-tungsten alloy interface bridge

Abstract

The invention relates to a preparation method and application of a hydrogen evolution electrocatalyst with an amorphous nickel-tungsten alloy interface bridge. The method comprises the following steps: placing W-series heteropolyacid at the downstream of a tubular furnace, placing a solid atmosphere source at the upstream of the tubular furnace, then introducing mixed gas into the tubular furnace, heating to 500-800 DEG C, and carrying out pyrolysis reduction for 1-5 hours to obtain the hydrogen evolution electrocatalyst with the amorphous nickel-tungsten alloy interface bridge, the W-series heteropolyacid is nickel tungstate NiWO4 or 6-tetraammonium tungstate nickelate (NH4) 4 [NiW6O24H6]), and the solid atmosphere source is urea, melamine, ammonium chloride or dicyandiamide. The catalyst is simple to prepare, adjustable in catalyst component, high in hydrogen evolution reaction activity and good in service stability.

Description

Technical Field

[0001] This invention belongs to the field of electrocatalytic materials, and in particular relates to a hydrogen evolution electrocatalyst with an amorphous nickel-tungsten alloy interface bridge, its preparation method, and its application. Background Technology

[0002] Producing green hydrogen through water electrolysis powered by renewable energy is a key approach to solving the global energy crisis. Electrochemical water splitting for hydrogen production has attracted much attention due to its environmental friendliness, high product purity, excellent energy conversion efficiency, and ability to store intermittent energy (Adv Mater, 33 (2021) 2007 100). To improve the hydrogen evolution rate and reduce energy loss, it is necessary to develop electrocatalysts with excellent catalytic activity.

[0003] Amorphous materials, due to their long-range disordered atomic arrangement and abundant uncoordinated sites, exhibit potential in the field of catalysis that surpasses their crystalline state (Chinese Patent CN202511155210.2). However, the thermodynamic instability of amorphous phases poses a severe challenge to their controllable preparation. Taking the nickel-tungsten (Ni-W) system as an example, the strong metallic bonding makes it prone to crystallization during heat treatment, making it difficult to maintain a stable amorphous structure. Existing methods for preparing amorphous Ni-W alloys (such as Chinese Patent CN201310563319) typically involve multiple complex processes such as magnetron sputtering deposition and subsequent high-temperature vacuum annealing, which are not only costly but also limit the controllable preparation and large-scale application of the materials.

[0004] More importantly, both amorphous and crystalline materials have their limitations. Recent research indicates that constructing an "amorphous / crystalline" heterointerface can synergize the advantages of both, effectively modulating the electronic structure and exposing more active sites (J Power Sources, 507(2021)230279). However, highly active heterointerfaces are prone to selective corrosion or elemental diffusion in electrolyte environments, leading to active layer stripping or interface passivation. Simultaneously, structural reconstruction of high-energy interfaces under reaction conditions can gradually deactivate pre-optimized active sites. These "interface fragility" problems severely restrict the practical application lifespan of high-performance catalysts (Coordin Chem Rev, 475(2023)214916). Therefore, constructing a novel interface structure that combines high activity and high stability has become a key breakthrough.

[0005] Against this backdrop, this project employs a simple and efficient strategy to construct an amorphous alloy "interface bridge" in situ between the amorphous and crystalline phases, achieving a dual improvement in activity and stability. This not only provides a new approach for developing long-life hydrogen evolution catalysts but also offers crucial theoretical insights for the stability design of all energy materials involving heterogeneous interfaces (such as batteries and fuel cells). Summary of the Invention

[0006] The purpose of this invention is to address the limitations of current technologies by providing a method for preparing and applying an electrocatalyst with an amorphous nickel-tungsten alloy interfacial bridge for hydrogen evolution electrocatalysis. This method uses urea, melamine, etc., as a solid atmosphere source and a W-based heteropolyacid as a metal source. Pyrolysis is performed in a mixed atmosphere of reducing and inert gases to control the crystallinity of nickel, thereby obtaining an amorphous nickel-tungsten alloy interfacial bridge electrocatalyst. This invention offers simple preparation, adjustable catalyst composition, high hydrogen evolution reaction activity, and good service stability.

[0007] The technical solution of this invention is: A method for preparing a hydrogen evolution electrocatalyst with an amorphous nickel-tungsten alloy interface bridge, the method comprising the following steps: W-series heteropolyacids are placed downstream of a tube furnace, and a solid atmosphere source is placed upstream of the tube furnace. Then, a mixed gas is introduced into the tube furnace, and the temperature is raised to 500-800℃ for pyrolysis and reduction for 1-5 h to obtain a hydrogen evolution electrocatalyst with an amorphous nickel-tungsten alloy interface bridge. The mixed gas consists of a reducing gas and an inert gas; the volume fractions of the reducing gas and the inert gas are 5% and 95%, respectively; the mass ratio of the W-series heteropolyacid to the solid atmosphere source is 1:1 to 1:20. The reducing gas is hydrogen, ammonia, or carbon monoxide, and the inert gas is nitrogen or argon. The total gas flow rate is 10-500 mL / min.

[0008] W-series heteropolyacids are nickel tungstate (NiWO4) or tetraammonium 6-tungstate (NH4)4[NiW6O] 24 H6].

[0009] The solid atmosphere source is urea, melamine, ammonium chloride, or dicyandiamide.

[0010] The heating rate of the tubular furnace during pyrolysis is 1-10℃ / min.

[0011] The solid atmosphere source and the W-series heteropolyacid are placed at a distance of 1~20 cm; The hydrogen evolution electrocatalyst with amorphous nickel-tungsten alloy interface bridges prepared by the method is used in water electrolysis for hydrogen production technology.

[0012] The specific steps for applying this electrocatalyst in the hydrogen production reaction are as follows: In a three-electrode system, a graphite rod is used as the counter electrode, a glassy carbon electrode with an amorphous nickel-tungsten alloy interface bridge for hydrogen evolution electrocatalyst is used as the working electrode, and mercury / mercury oxide is used as the reference electrode. Electrolysis is carried out in 0.5~2 M KOH electrolyte at a constant voltage in the potential range of -0.3-0V to obtain hydrogen gas. The method for preparing the working electrode includes the following steps: The obtained electrocatalyst with amorphous nickel-tungsten alloy interface bridges was added to the mixed solution and sonicated for 15-45 min to obtain catalyst ink; then the catalyst ink was coated on a glassy carbon electrode to obtain the working electrode. The mixed solution consists of anhydrous ethanol and 5 wt% Nafion solution; each 1 mL of the mixed solution consists of 970 µL of anhydrous ethanol and 30 µL of Nafion solution. Add 5-10 mg of catalyst per 1 mL of mixed solution; Each glassy carbon electrode, measuring 5 to 10 square millimeters, is coated with 10 to 20 µL of catalyst ink.

[0013] By introducing a mixture of reducing and inert gases into a solid atmosphere, the crystallinity of the nickel-tungsten alloy at the interface was successfully controlled, favoring the formation of an amorphous phase. This amorphous phase provides abundant catalytic active sites. Benefiting from this, the prepared electrocatalyst with an amorphous nickel-tungsten alloy interfacial bridge exhibited excellent hydrogen evolution activity in 1 M KOH electrolyte, reaching 10 mA cm⁻¹. -2 The overpotential required for the current density is only 19 mV, and the overpotential rises by only 1 mV after 10,000 cycles.

[0014] The essential features of this invention are: The preparation method of this invention is simple. By introducing a mixture of reducing and inert gases into a solid atmosphere source, the crystallinity of the nickel-tungsten alloy at the interface is successfully controlled. Specifically, during the heating process in the tube furnace, the solid atmosphere source gradually decomposes and releases ammonia, which, together with the introduced reducing and inert gases, forms a mixed atmosphere. Simultaneously, the heteropolyacid is gradually reduced to tungsten dioxide, metallic nickel, and the nickel-tungsten alloy in the reducing atmosphere. Due to the presence of ammonia, it coordinates with nickel and tungsten atoms in the nickel-tungsten alloy at high temperatures, effectively inhibiting atomic migration and thus maintaining the nickel-tungsten alloy in an amorphous state. During the programmed cooling stage of the tube furnace, the coordination effect of ammonia weakens and it detaches from the catalyst, finally forming an electrocatalyst with an amorphous nickel-tungsten alloy interface bridge. In this process, the heteropolyacid, as a precursor with a definite nickel / tungsten atomic ratio, can precisely control the content of metallic nickel in the final catalyst, thereby avoiding the inevitable crystallization of the nickel-tungsten alloy caused by excessive nickel content. The obtained electrocatalyst with an amorphous nickel-tungsten alloy interface bridge structure exhibits excellent electrocatalytic hydrogen evolution performance, combining high activity and good stability. Its comprehensive catalytic performance is significantly better than that of conventional heterojunction catalyst materials.

[0015] The beneficial effects of this invention are: This invention successfully prepared a hydrogen evolution electrocatalyst with an amorphous nickel-tungsten alloy interfacial bridge by introducing a reducing and inert mixed gas into a solid atmosphere source to control the crystallinity of the nickel-tungsten alloy at the amorphous nickel / crystalline tungsten oxide interface. The prepared catalyst has tunable composition and high hydrogen evolution reaction activity. In Example 1, the catalyst with the amorphous nickel-tungsten alloy interfacial bridge achieved a hydrogen evolution reaction activity of 10 mA cm⁻¹ in 1 M KOH solution. -2 The overpotential at the current density is only 19 mV, which is 17 mV lower than the catalyst with crystalline nickel-tungsten alloy interfacial bridges in Example 5. It exhibits good stability, with the overpotential increasing by only 1 mV after 10,000 cycles, demonstrating promising industrial application potential. This invention provides a feasible method for preparing electrocatalysts with amorphous nickel-tungsten alloy interfacial bridges. It offers a new approach for developing long-life hydrogen evolution catalysts and provides crucial theoretical guidance for the stability design of all energy materials involving heterogeneous interfaces (such as batteries and fuel cells). Attached Figure Description

[0016] Figure 1 The image shows the X-ray diffraction (XRD) pattern of the electrocatalyst with amorphous nickel-tungsten alloy interface bridges obtained in Example 1. Figure 2 The image shows a transmission electron microscope (TEM) image of the electrocatalyst with amorphous nickel-tungsten alloy interface bridges obtained in Example 1. Figure 3 Linear current-voltage (LSV) curves of the electrocatalyst with amorphous nickel-tungsten alloy interface bridges obtained in Example 1. Figure 4 The linear current-voltage (LSV) curves of the electrocatalyst with amorphous nickel-tungsten alloy interface bridge obtained in Example 1 before and after cycling. Figure 5 The image shows the X-ray diffraction (XRD) pattern of the electrocatalyst with crystalline nickel-tungsten alloy interface bridges obtained in Example 5. Figure 6 This is a transmission electron microscope (TEM) image of the electrocatalyst with crystalline nickel-tungsten alloy interface bridges obtained in Example 5. Figure 7 Linear voltammetry (LSV) curves of the electrocatalyst with crystalline nickel-tungsten alloy interface bridges obtained in Example 5. Detailed Implementation

[0017] The technical solution of the present invention will be further described below with reference to the embodiments. These embodiments should not be construed as limiting the technical solution, but rather as a more detailed description of certain aspects, characteristics and implementation schemes of the present invention.

[0018] In the following embodiments, the dimensions of the quartz tube used in the tubular furnace are: 60cm in length, 4.4cm in inner diameter, and 5.0cm in outer diameter; the two ceramic boats are 10cm apart. Throughout the pyrolysis process, the gas flow maintains a constant total velocity continuously passing through the quartz tube.

[0019] Example 1: An electrocatalyst with an amorphous nickel-tungsten alloy interfacial bridge: 0.055 g of nickel tungstate (NiWO4) was accurately weighed and placed in a ceramic boat at the downstream end of a tube furnace, and 0.55 g of urea was placed in a ceramic boat at the upstream end of the tube furnace. The reducing gas introduced into the tube furnace was hydrogen, and the inert gas was nitrogen, with volume fractions of 5% hydrogen and 95% nitrogen, respectively. The total gas flow rate was 60 mL / min, the heating rate was 5 °C / min, the temperature was 600 °C, and the holding time was 2 h.

[0020] The XRD pattern of the electrocatalyst with amorphous nickel-tungsten alloy interface bridges prepared in Example 1 is shown below. Figure 1 As shown, no diffraction peaks related to the nickel-tungsten alloy appear, indicating that the nickel-tungsten alloy is in an amorphous state.

[0021] TEM image of the electrocatalyst with amorphous nickel-tungsten alloy interface bridges prepared in Example 1 is shown below. Figure 2 As shown, the presence of obvious amorphous nickel-tungsten alloy and crystalline WO2 can be observed. Figure 1-2 This indicates that an electrocatalyst with an amorphous nickel-tungsten alloy interface bridge has been successfully constructed. The nickel-tungsten alloy is in an amorphous state in the catalyst, and the presence of the amorphous nickel-tungsten alloy interface bridge can be directly observed by TEM. The presence of the amorphous nickel-tungsten alloy interface bridge provides abundant active sites for the electrocatalytic hydrogen evolution reaction and improves the reaction activity.

[0022] The LSV curve of the electrocatalyst with amorphous nickel-tungsten alloy interfacial bridge prepared in Example 1 is shown below. Figure 3 As shown, the hydrogen evolution reaction activity of this catalyst was tested in 1 M potassium hydroxide (KOH) electrolyte using a Chenhua 760D electrochemical workstation. A three-electrode system was employed, with a graphite rod as the counter electrode, a glassy carbon electrode coated with the catalyst as the working electrode, and a mercury / mercury oxide electrode as the reference electrode. The test results indicate that the prepared electrocatalyst with an amorphous nickel-tungsten alloy interfacial bridge exhibits excellent catalytic activity, reaching 10 mA cm⁻¹ in 1 M KOH solution. -2 The overpotential required for the current density is only 19 mV, and after 10,000 cycles, the overpotential only increases by 2 mV. Figure 4 This indicates that the electrocatalyst with the amorphous nickel-tungsten alloy interface bridge exhibits high activity in the hydrogen evolution reaction, excellent catalytic performance, and good service stability.

[0023] The working electrode was prepared as follows: 7 mg of catalyst was dispersed in a mixed solution of 970 μL anhydrous ethanol and 30 μL of 5 wt% Nafion and sonicated for 30 min. Then, 10 μL of the sonicated catalyst ink was drop-coated onto a glassy carbon electrode with a diameter of 3 mm to prepare the working electrode.

[0024] Example 2: An electrocatalyst with an amorphous nickel-tungsten alloy interfacial bridge: 0.055 g of nickel tungstate (NiWO4) was accurately weighed and placed in a ceramic boat downstream of a tube furnace. 0.80 g of ammonium chloride was placed in the same ceramic boat upstream of the tube furnace. The reducing gas introduced into the tube furnace was hydrogen, and the inert gas was nitrogen, with volume fractions of 5% hydrogen and 95% nitrogen, respectively. The total gas flow rate was 60 mL / min, the heating rate was 5 °C / min, the temperature was 600 °C, and the holding time was 2 h. The prepared electrocatalyst reached 10 mA cm⁻¹ in 1 M KOH solution. -2 The overpotential required for the current density is only 24 mV.

[0025] Example 3: An electrocatalyst with an amorphous nickel-tungsten alloy interfacial bridge: 0.055 g of nickel tungstate (NiWO4) was accurately weighed and placed in a ceramic boat downstream of a tube furnace. 0.90 g of melamine was placed in the same ceramic boat upstream of the tube furnace. The reducing gas introduced into the tube furnace was hydrogen, and the inert gas was nitrogen, with volume fractions of 5% hydrogen and 95% nitrogen, respectively. The total gas flow rate was 60 mL / min, the heating rate was 5℃ / min, the temperature was 600℃, and the holding time was 2 h. The prepared electrocatalyst reached 10 mA cm⁻¹ in 1 M KOH solution. -2 The overpotential required for the current density is only 26 mV.

[0026] Example 4: An electrocatalyst with an amorphous nickel-tungsten alloy interfacial bridge: 0.055 g of nickel tungstate (NiWO4) was accurately weighed and placed in a ceramic boat in a tube furnace. The reducing gas introduced into the tube furnace was ammonia, and the inert gas was nitrogen, with volume fractions of 5% ammonia and 95% nitrogen, respectively. The total gas flow rate was 60 mL / min, the heating rate was 5℃ / min, the temperature was 600℃, and the holding time was 2 h. The prepared electrocatalyst reached 10 mA cm⁻¹ in 1 M KOH solution. -2 The overpotential required for the current density is only 26mV.

[0027] Example 5: An electrocatalyst with a crystalline nickel-tungsten alloy interfacial bridge: 0.055 g of nickel tungstate (NiWO4) was accurately weighed and placed in a ceramic boat downstream of a tube furnace. The reducing gas introduced into the tube furnace was hydrogen, and the inert gas was nitrogen, with volume fractions of 5% hydrogen and 95% nitrogen, respectively. The total gas flow rate was 60 mL / min, the heating rate was 5℃ / min, the temperature was 700℃, and the holding time was 2 h. The prepared electrocatalyst reached 10 mA cm⁻¹ in 1 M KOH solution. -2 The required overpotential for the current density is 36mV The XRD pattern of the electrocatalyst with crystalline nickel-tungsten alloy interface bridges prepared in Example 5 is shown below. Figure 5 As shown, the appearance of diffraction peaks in the nickel-tungsten alloy indicates that the alloy is in a crystalline state.

[0028] TEM image of the electrocatalyst with crystalline nickel-tungsten alloy interface bridges prepared in Example 5 is shown below. Figure 4 As shown, the presence of crystalline nickel-tungsten alloy and crystalline WO2 can be observed.

[0029] The LSV curve of the electrocatalyst with crystalline nickel-tungsten alloy interface bridges prepared in Example 5 is shown below. Figure 7 As shown, the electrocatalyst with crystalline nickel-tungsten alloy interfacial bridges reaches 10 mA cm⁻¹ in 1 M KOH solution. -2 The overpotential at the current density is as high as 36 mV. The test results show that, compared with the amorphous nickel-tungsten alloy interface bridge, the catalyst with the crystalline nickel-tungsten alloy interface bridge provides a significantly fewer number of active sites, resulting in a decrease in its catalytic performance and a higher required overpotential.

[0030] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

[0031] Matters not covered in this invention are common knowledge.

Claims

1. A method for preparing a hydrogen evolution electrocatalyst with an amorphous nickel-tungsten alloy interface bridge, characterized in that, The method includes the following steps: W-series heteropolyacids are placed downstream of a tube furnace, and a solid atmosphere source is placed upstream of the tube furnace. Then, a mixed gas is introduced into the tube furnace, and the temperature is raised to 500-800℃ for pyrolysis and reduction for 1-5 h to obtain a hydrogen evolution electrocatalyst with an amorphous nickel-tungsten alloy interface bridge. The mixed gas consists of a reducing gas and an inert gas; the volume fractions of the reducing gas and the inert gas are 5% and 95%, respectively; the mass ratio of the W-series heteropolyacid to the solid atmosphere source is 1:1 to 1:

20. The reducing gas is hydrogen, ammonia, or carbon monoxide, and the inert gas is nitrogen or argon. W-series heteropolyacids are nickel tungstate (NiWO4) or tetraammonium 6-tungstate (NH4)4[NiW6O] 24 H6]); The solid atmosphere source is urea, melamine, ammonium chloride, or dicyandiamide.

2. The method for preparing the hydrogen evolution electrocatalyst with an amorphous nickel-tungsten alloy interface bridge as described in claim 1, characterized in that, The heating rate of the tubular furnace during pyrolysis is 1-10℃ / min.

3. The method for preparing the hydrogen evolution electrocatalyst with an amorphous nickel-tungsten alloy interface bridge as described in claim 1, characterized in that, The solid atmosphere source and the W-series heteropolyacid are placed at a distance of 1 to 20 cm.

4. The method for preparing the hydrogen evolution electrocatalyst with an amorphous nickel-tungsten alloy interface bridge as described in claim 1, characterized in that, The total gas flow rate is 10-500 mL / min.

5. The application of the hydrogen evolution electrocatalyst with amorphous nickel-tungsten alloy interface bridge prepared by the method described in claim 1, characterized in that, Used as an electrocatalyst in the electrolysis of water to produce hydrogen.

6. The application as described in claim 5, characterized in that, Includes the following steps: In a three-electrode system, a graphite rod is used as the counter electrode, a glassy carbon electrode with an amorphous nickel-tungsten alloy interface bridge for hydrogen evolution electrocatalyst is used as the working electrode, and mercury oxide is used as the reference electrode. Electrolysis is carried out in 0.5~2 M KOH electrolyte under a constant voltage in the potential range of -0.3-0V to obtain hydrogen gas. The method for preparing the working electrode includes the following steps: The hydrogen evolution electrocatalyst with the obtained amorphous nickel-tungsten alloy interface bridge was added to the mixed solution and sonicated for 15-45 min to obtain catalyst ink; then the catalyst ink was coated on the glassy carbon electrode to obtain the working electrode. The mixed solution consists of anhydrous ethanol and a 5 wt% Nafion solution; each 1 mL of the mixed solution consists of 970 µL of anhydrous ethanol and 30 µL of Nafion solution. Add 5-10 mg of catalyst per 1 mL of mixed solution; Each glassy carbon electrode, measuring 5 to 10 square millimeters, is coated with 10 to 20 µL of catalyst ink.

Images