Ni4Mo / Ni(OH)2 / NF catalyst, and preparation method and application thereof

Abstract

The application discloses a kind of Ni4Mo / Ni (OH) 2 / NF catalyst and its preparation method and application, belong to the technical field of electrocatalytic hydrogen evolution.The preparation method includes: the pretreated foam nickel is obtained by ultrasonic cleaning to foam nickel;Sodium citrate, molybdenum source and nickel source are dissolved in water, and the reaction solution is obtained;With pretreated foam nickel as working electrode, platinum sheet as counter electrode, Ag / AgCl as reference electrode, reaction solution as electrolyte, using voltammetry cyclic scanning method is electrodeposited, and the Ni4Mo / Ni (OH) 2 / NF catalyst is obtained.The application also discloses the Ni4Mo / Ni (OH) 2 / NF catalyst prepared by the above preparation method and its application.The application can solve the problems of existing Ni-Mo alloy catalyst synthesis, insufficient exposure of active component, poor combination ability of active component and substrate and poor long-term stability, and has high practical application value.

Description

Technical Field

[0001] This invention relates to the field of electrocatalytic hydrogen evolution technology, specifically to a Ni4Mo / Ni(OH)2 / NF catalyst, its preparation method, and its application. Background Technology

[0002] With the global energy structure transitioning towards cleaner and lower-carbon energy sources, hydrogen energy, as a highly efficient and renewable green energy carrier, has received increasing attention. Electrocatalytic water splitting for hydrogen production can convert electrical energy into high-purity hydrogen under mild conditions and is considered one of the important pathways to achieve large-scale hydrogen energy applications. The hydrogen evolution reaction (HER), as a half-reaction of water splitting, typically exhibits slow kinetics, requiring highly efficient electrocatalysts to reduce reaction overpotential and improve energy conversion efficiency. Currently, platinum (Pt)-based materials are considered the best-performing catalysts for HER, but their high cost and scarcity severely limit their large-scale application. Therefore, developing low-cost, highly active, and highly stable non-precious metal HER catalysts has become a key research focus in this field.

[0003] Transition metal alloys (especially nickel-based alloys) have shown great promise in the field of HER catalysis due to their excellent electrical conductivity, tunable electronic structure, and good resistance to alkaline environments. In nickel-molybdenum (Ni-Mo) alloys, the introduction of molybdenum can optimize the electronic state density of nickel, promote water dissociation and hydrogen intermediate adsorption / desorption processes, thereby significantly improving its intrinsic catalytic activity.

[0004] However, traditional Ni-Mo alloy catalyst preparation methods (such as high-temperature reduction and hydrothermal synthesis) are often cumbersome, energy-intensive, and have limited bonding between the active component and the substrate, affecting their long-term stability. Furthermore, achieving high exposure of the active component, promoting mass transfer processes, and maintaining structural stability remain key challenges in the design of such catalysts. Summary of the Invention

[0005] The problem to be solved by this invention is to provide a Ni4Mo / Ni(OH)2 / NF catalyst, its preparation method and application, so as to solve the problems of cumbersome synthesis, insufficient exposure of active components, poor bonding ability between active components and substrate and poor long-term stability of existing Ni-Mo alloy catalysts.

[0006] The technical solution adopted to solve its technical problem is a method for preparing a Ni4Mo / Ni(OH)2 / NF catalyst, which includes the following steps: (1) The nickel foam is ultrasonically cleaned to obtain pretreated nickel foam; (2) Dissolve trisodium citrate, molybdenum source and nickel source together in water to obtain a reaction solution; (3) Using pretreated nickel foam as the working electrode, platinum sheet as the counter electrode, Ag / AgCl as the reference electrode, and reaction solution as the electrolyte, electrodeposition was performed by voltammetric cyclic scanning method to obtain Ni4Mo / Ni(OH)2 / NF catalyst.

[0007] The beneficial effects of the above technical solution adopted in this invention are as follows: Nickel foam, as a three-dimensional porous conductive substrate, has a high specific surface area, excellent conductivity and mechanical stability, providing an ideal platform for loading active materials and reaction mass transfer. Based on this, this invention uses the voltammetric cyclic scanning method to perform one-step electrodeposition of Ni and Mo on the surface of nickel foam, which better realizes the shared loading of Ni4Mo alloy and Ni(OH)2 on the catalyst surface. The resulting Ni4Mo / Ni(OH)2 / NF catalyst has good HER activity and good stability during long-term operation.

[0008] Preferably, step (1) includes the following steps: ultrasonically cleaning the nickel foam in hydrochloric acid, acetone, anhydrous ethanol and water for 10-20 min respectively, and then drying it under vacuum to obtain pretreated nickel foam.

[0009] More preferably, step (1) includes the following steps: ultrasonically cleaning the nickel foam in hydrochloric acid, acetone, anhydrous ethanol and water for 15 min in sequence, and then drying it under vacuum to obtain pretreated nickel foam.

[0010] More preferably, the nickel foam size is 1 cm × 4 cm.

[0011] More preferably, the molar concentration of hydrochloric acid is 0.8~1.2 M.

[0012] More preferably, the molar concentration of hydrochloric acid is 1 M.

[0013] Preferably, in step (2), the molybdenum source is sodium molybdate, ammonium molybdate, or molybdenum trioxide; the nickel source is nickel nitrate, nickel sulfate, or nickel chloride; and the mass ratio of trisodium citrate, molybdenum source, and nickel source is 10:(0.4~0.6):(0.5~0.7).

[0014] More preferably, in step (2), the molybdenum source is sodium molybdate; the nickel source is nickel nitrate; and the mass ratio of trisodium citrate, molybdenum source and nickel source is 10:0.5:0.6.

[0015] Preferably, the electrodeposition using the voltammetric cyclic scanning method in step (3) includes the following steps: performing 90 to 110 cyclic voltammetric scans at a scan rate of 95 to 105 mV / s on an electrochemical workstation within a voltage range of -6 to -1 V relative to the reference electrode.

[0016] More preferably, the electrodeposition using the cyclic voltammetric scanning method in step (3) includes the following steps: performing 100 cycles of cyclic voltammetric scanning at a scan rate of 100 mV / S on an electrochemical workstation within a voltage range of -4 to -2 V relative to the reference electrode.

[0017] The present invention also provides a Ni4Mo / Ni(OH)2 / NF catalyst prepared by the above preparation method.

[0018] This invention also provides the application of the above-mentioned Ni4Mo / Ni(OH)2 / NF catalyst in electrocatalytic hydrogen evolution.

[0019] The present invention has the following beneficial effects: This invention employs a simple and efficient one-step electrodeposition strategy to directly prepare a Ni4Mo / Ni(OH)2 / NF catalyst with a Ni4Mo alloy and Ni(OH)2 heterostructure on nickel foam for electrocatalytic hydrogen evolution reaction (HER) in alkaline media. The method of this invention not only simplifies the catalyst preparation process but also achieves tight coupling between the active component and the substrate, endowing the catalyst with abundant active sites and a stable three-dimensional structure. The Ni4Mo / Ni(OH)2 / NF catalyst prepared by this invention exhibits excellent HER activity and long-term stability, with performance approaching that of some noble metal-based catalysts. This invention provides a new approach for designing efficient and stable non-noble metal HER catalysts and is expected to promote the practical application of electrocatalytic hydrogen production technology. Attached Figure Description

[0020] Figure 1 A schematic diagram of the preparation process of the Ni4Mo / Ni(OH)2 / NF catalyst; Figure 2 The images show SEM images of the Ni4Mo / Ni(OH)2 / NF catalyst prepared in Example 1; where (a) is the SEM image at 50 μm; (b) is the SEM image at 5 μm; (c) is the SEM image at 2 μm; and (d) is the SEM image at 100 nm. Figure 3 SEM images of the Ni / NF catalyst prepared in Comparative Example 1 and the Mo / NF catalyst prepared in Comparative Example 2 are shown below. (a) is the SEM image of the Ni / NF catalyst prepared in Comparative Example 1 at 2 μm; (b) is the SEM image of the Ni / NF catalyst prepared in Comparative Example 1 at 100 nm; (c) is the SEM image of the Mo / NF catalyst prepared in Comparative Example 2 at 2 μm; and (d) is the SEM image of the Mo / NF catalyst prepared in Comparative Example 2 at 100 nm. Figure 4SEM images of the Ni4Mo / NF catalysts prepared in Comparative Examples 3-5 are shown below. (a) is the SEM image of the Ni4Mo / NF catalyst prepared in Comparative Example 3 at 40 μm; (b) is the SEM image of the Ni4Mo / NF catalyst prepared in Comparative Example 3 at 5 μm; (c) is the SEM image of the Ni4Mo / NF catalyst prepared in Comparative Example 4 at 40 μm; (d) is the SEM image of the Ni4Mo / NF catalyst prepared in Comparative Example 4 at 5 μm; (e) is the SEM image of the Ni4Mo / NF catalyst prepared in Comparative Example 5 at 40 μm; and (f) is the SEM image of the Ni4Mo / NF catalyst prepared in Comparative Example 5 at 5 μm. Figure 5 The image shows the EDS elemental distribution of the Ni4Mo / Ni(OH)2 / NF catalyst prepared in Example 1. Figure 6 The image shows a TEM image of the Ni4Mo / Ni(OH)2 / NF catalyst prepared in Example 1. Figure 7 The electron diffraction pattern of the Ni4Mo / Ni(OH)2 / NF catalyst prepared in Example 1 is shown below. Figure 8 The image shows an HRTEM image of the Ni4Mo / Ni(OH)2 / NF catalyst prepared in Example 1. Figure 9 The image shows the XRD pattern of Ni4Mo / Ni(OH)2 on the surface of the Ni4Mo / Ni(OH)2 catalyst prepared in Example 1. Figure 10 Raman spectra of the Ni4Mo / Ni(OH)2 / NF catalyst prepared in Example 1, the Ni / NF catalyst prepared in Comparative Example 1, and the Mo / NF catalyst prepared in Comparative Example 2. Figure 11 XPS spectra of the Ni4Mo / Ni(OH)2 / NF catalyst prepared in Example 1, the Ni / NF catalyst prepared in Comparative Example 1, and the Mo / NF catalyst prepared in Comparative Example 2; wherein, (a) is the full XPS spectrum of the Ni4Mo / Ni(OH)2 / NF catalyst; (b) is the fine Mo 3d XPS spectrum of the Mo / NF catalyst and the Ni4Mo / Ni(OH)2 / NF catalyst; (c) is the fine Ni 2p XPS spectrum of the Ni / NF catalyst and the Ni4Mo / Ni(OH)2 / NF catalyst; and (d) is the fine O 1s XPS spectrum of the Mo / NF catalyst, the Ni / NF catalyst, and the Ni4Mo / Ni(OH)2 / NF catalyst. Figure 12The HER activity diagrams are for nickel foam, the Ni4Mo / Ni(OH)2 / NF catalyst prepared in Example 1, the Ni / NF catalyst prepared in Comparative Example 1, and the Mo / NF catalyst prepared in Comparative Example 2; where (a) is the LSV curve and (b) is the overpotential diagram at different current densities. Figure 13 The reaction kinetics analysis diagrams for nickel foam, the Ni4Mo / Ni(OH)2 / NF catalyst prepared in Example 1, the Ni / NF catalyst prepared in Comparative Example 1, and the Mo / NF catalyst prepared in Comparative Example 2 are shown; where (a) is a Tafel curve and (b) is an exchange current density diagram. Figure 14 Electrochemical impedance spectroscopy of nickel foam, Ni4Mo / Ni(OH)2 / NF catalyst prepared in Example 1, Ni / NF catalyst prepared in Comparative Example 1, and Mo / NF catalyst prepared in Comparative Example 2. Figure 15 The intrinsic activity analysis diagrams are for nickel foam, the Ni4Mo / Ni(OH)2 / NF catalyst prepared in Example 1, the Ni / NF catalyst prepared in Comparative Example 1, and the Mo / NF catalyst prepared in Comparative Example 2; where (a) is the Cdl value result diagram; and (b) is the LSV curve normalized by ECSA. Figure 16 The figure shows the stability analysis of the Ni4Mo / Ni(OH)2 / NF catalyst prepared in Example 1; where (a) is the stability analysis of Ni4Mo / Ni(OH)2 / NF at 500 mA cm⁻¹. -2 (a) SEM image of Ni4Mo / Ni(OH)2 / NF at 20 μm after 500 h of operation at current density; (b) SEM image of Ni4Mo / Ni(OH)2 / NF at 500 mA cm⁻¹. -2 (c) SEM image of Ni4Mo / Ni(OH)2 / NF at 100 nm after 500 h of operation at current density; -2 Overpotential diagram during operation at a current density for 500 h. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention; that is, the described embodiments are only a part of the embodiments of this invention, and not all of them.

[0022] Therefore, the following detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0023] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0024] Example 1 A method for preparing a Ni4Mo / Ni(OH)2 / NF catalyst includes the following steps: (1) Cut the nickel foam into small pieces with a size of 1 cm × 4 cm, and then ultrasonically clean them for 15 min in 1 M hydrochloric acid, acetone, anhydrous ethanol and deionized water to remove the oxide layer and impurities on the surface. Then dry them under vacuum to obtain pretreated nickel foam. (2) Weigh 10 g of trisodium citrate dihydrate (C6H5Na3O7·2H2O), 0.5 g of sodium molybdate dihydrate (NaMoO4·2H2O) and 0.6 g of nickel nitrate hexahydrate (Ni(NO3)2·6H2O), dissolve them in 70 mL of deionized water, and stir thoroughly to obtain a green and transparent reaction solution; (3) A three-electrode system is used, with an effective area of ​​1 cm². 2 Pretreated nickel foam was used as the working electrode, platinum sheet as the counter electrode, and Ag / AgCl as the reference electrode. The reaction solution was used as the electrolyte. Cyclic voltammetry (CV) was performed for 100 cycles in the voltage range of -4 to -2 V (vs. Ag / AgCl) at a scan rate of 100 mV / s on an electrochemical workstation. After the reaction was completed, the catalyst was washed with deionized water and ethanol in sequence, and then dried in a vacuum drying oven at 60℃ for 12 h to obtain the Ni4Mo / Ni(OH)2 / NF catalyst.

[0025] In this embodiment, the preparation process of the Ni4Mo / Ni(OH)2 / NF catalyst is as follows: Figure 1 As shown.

[0026] Example 2 A method for preparing a Ni4Mo / Ni(OH)2 / NF catalyst includes the following steps: (1) Cut the nickel foam into small pieces with a size of 1 cm × 2 cm, and then ultrasonically clean them for 10 min in hydrochloric acid, acetone, anhydrous ethanol and deionized water with a molar concentration of 0.8 M, respectively, to remove the oxide layer and impurities on the surface. Then dry them under vacuum to obtain pretreated nickel foam. (2) Weigh 10 g C6H5Na3O7·2H2O, 0.4 g NaMoO4·2H2O and 0.5 g Ni(NO3)2·6H2O, dissolve them in 70 mL of deionized water, and stir thoroughly to obtain a green and transparent reaction solution; (3) A three-electrode system is used, with an effective area of ​​1 cm². 2 Pretreated nickel foam was used as the working electrode, platinum sheet as the counter electrode, and Ag / AgCl as the reference electrode. The reaction solution was used as the electrolyte. Cyclic voltammetry was performed for 90 cycles in the voltage range of -6 to -1 V (vs. Ag / AgCl) at a scan rate of 95 mV / s on an electrochemical workstation. After the reaction was completed, the catalyst was washed with deionized water and ethanol in sequence, and then dried in a vacuum drying oven at 60℃ for 12 h to obtain the Ni4Mo / Ni(OH)2 / NF catalyst.

[0027] Example 3 A method for preparing a Ni4Mo / Ni(OH)2 / NF catalyst includes the following steps: (1) Cut the nickel foam into small pieces with a size of 2 cm × 4 cm, and then ultrasonically clean them for 15 min in 1.2 M hydrochloric acid, acetone, anhydrous ethanol and deionized water to remove the oxide layer and impurities on the surface. Then dry them under vacuum to obtain pretreated nickel foam. (2) Weigh 10 g C6H5Na3O7·2H2O, 0.6 g NaMoO4·2H2O and 0.7 g Ni(NO3)2·6H2O, dissolve them in 70 mL of deionized water, and stir thoroughly to obtain a green and transparent reaction solution; (3) A three-electrode system is used, with an effective area of ​​2 cm². 2 Pretreated nickel foam was used as the working electrode, platinum sheet as the counter electrode, and Ag / AgCl as the reference electrode. The reaction solution was used as the electrolyte. Cyclic voltammetry was performed for 110 cycles at a scan rate of 105 mV / s in the voltage range of -4 to -2 V (vs. Ag / AgCl) on an electrochemical workstation. After the reaction was completed, the catalyst was washed with deionized water and ethanol in sequence, and then dried in a vacuum drying oven at 60℃ for 12 h to obtain the Ni4Mo / Ni(OH)2 / NF catalyst.

[0028] Comparative Example 1 A method for preparing a Ni / NF catalyst includes the following steps: (1) Cut the nickel foam into small pieces with a size of 1 cm × 4 cm, and then ultrasonically clean them for 15 min in hydrochloric acid, acetone, anhydrous ethanol and deionized water with a molar concentration of 1 M, respectively, to remove the oxide layer and impurities on the surface. Then dry them under vacuum to obtain pretreated nickel foam. (2) Weigh 10 g C6H5Na3O7·2H2O and 0.6 g Ni(NO3)2·6H2O, dissolve them in 70 mL of deionized water, and stir thoroughly to obtain the reaction solution; (3) A three-electrode system is used, with an effective area of ​​1 cm². 2 Pretreated nickel foam was used as the working electrode, platinum sheet as the counter electrode, and Ag / AgCl as the reference electrode. The reaction solution was used as the electrolyte. Cyclic voltammetry was performed for 100 cycles in the voltage range of -4 to -2 V (vs. Ag / AgCl) at a scan rate of 100 mV / s on an electrochemical workstation. After the reaction was completed, the catalyst was washed with deionized water and ethanol in sequence, and then dried in a vacuum drying oven at 60℃ for 12 h to obtain the Ni / NF catalyst.

[0029] Comparative Example 2 A method for preparing a Mo / NF catalyst includes the following steps: (1) Cut the nickel foam into small pieces with a size of 1 cm × 4 cm, and then ultrasonically clean them for 15 min in 1 M hydrochloric acid, acetone, anhydrous ethanol and deionized water to remove the oxide layer and impurities on the surface. Then dry them under vacuum to obtain pretreated nickel foam. (2) Weigh 10 g C6H5Na3O7·2H2O and 0.5 g NaMoO4·2H2O, dissolve them in 70 mL of deionized water, and stir thoroughly to obtain the reaction solution; (3) A three-electrode system is used, with an effective area of ​​1 cm². 2 Pretreated nickel foam was used as the working electrode, platinum sheet as the counter electrode, and Ag / AgCl as the reference electrode. The reaction solution was used as the electrolyte. Cyclic voltammetry was performed for 100 cycles in the voltage range of -4 to -2 V (vs. Ag / AgCl) at a scan rate of 100 mV / s on an electrochemical workstation. After the reaction was completed, the catalyst was washed with deionized water and ethanol in sequence, and then dried in a vacuum drying oven at 60℃ for 12 h to obtain the Mo / NF catalyst.

[0030] Comparative Example 3 A method for preparing a Ni4Mo / NF catalyst includes the following steps: (1) Cut the nickel foam into small pieces with a size of 1 cm × 4 cm, and then ultrasonically clean them for 15 min in 1 M hydrochloric acid, acetone, anhydrous ethanol and deionized water to remove the oxide layer and impurities on the surface. Then dry them under vacuum to obtain pretreated nickel foam. (2) Weigh 10 g C6H5Na3O7·2H2O, 0.5 g NaMoO4·2H2O and 0.6 g Ni(NO3)2·6H2O, dissolve them in 70 mL of deionized water, and stir thoroughly to obtain a green and transparent reaction solution; (3) A three-electrode system is used, with an effective area of ​​1 cm². 2 Pretreated nickel foam was used as the working electrode, platinum sheet as the counter electrode, Ag / AgCl as the reference electrode, and the reaction solution as the electrolyte. Electrolysis was performed at 1 A / cm on an electrochemical workstation. 2 Electrodeposition was performed at a constant current density for 600 s. After the reaction, the catalyst was washed with deionized water and ethanol in sequence, and then dried in a vacuum drying oven at 60℃ for 12 h to obtain the Ni4Mo / NF catalyst.

[0031] Comparative Example 4 A method for preparing a Ni4Mo / NF catalyst includes the following steps: (1) Cut the nickel foam into small pieces with a size of 1 cm × 4 cm, and then ultrasonically clean them for 15 min in 1 M hydrochloric acid, acetone, anhydrous ethanol and deionized water to remove the oxide layer and impurities on the surface. Then dry them under vacuum to obtain pretreated nickel foam. (2) Weigh 10 g C6H5Na3O7·2H2O, 0.5 g NaMoO4·2H2O and 0.6 g Ni(NO3)2·6H2O, dissolve them in 70 mL of deionized water, and stir thoroughly to obtain a green and transparent reaction solution; (3) A three-electrode system is used, with an effective area of ​​1 cm². 2 Pretreated nickel foam was used as the working electrode, a platinum sheet as the counter electrode, and Ag / AgCl as the reference electrode. The reaction solution was used as the electrolyte, and the reaction was carried out at 2 A / cm on an electrochemical workstation. 2 Electrodeposition was performed at a constant current density for 600 s. After the reaction, the catalyst was washed with deionized water and ethanol in sequence, and then dried in a vacuum drying oven at 60℃ for 12 h to obtain the Ni4Mo / NF catalyst.

[0032] Comparative Example 5 A method for preparing a Ni4Mo / NF catalyst includes the following steps: (1) Cut the nickel foam into small pieces with a size of 1 cm × 4 cm, and then ultrasonically clean them for 15 min in 1 M hydrochloric acid, acetone, anhydrous ethanol and deionized water to remove the oxide layer and impurities on the surface. Then dry them under vacuum to obtain pretreated nickel foam. (2) Weigh 10 g C6H5Na3O7·2H2O, 0.5 g NaMoO4·2H2O and 0.6 g Ni(NO3)2·6H2O, dissolve them in 70 mL of deionized water, and stir thoroughly to obtain a green and transparent reaction solution; (3) A three-electrode system is used, with an effective area of ​​1 cm². 2 Pretreated nickel foam was used as the working electrode, platinum sheet as the counter electrode, Ag / AgCl as the reference electrode, and the reaction solution as the electrolyte. Electrolysis was performed at 3 A / cm on an electrochemical workstation. 2 Electrodeposition was performed at a constant current density for 600 s. After the reaction, the catalyst was washed with deionized water and ethanol in sequence, and then dried in a vacuum drying oven at 60℃ for 12 h to obtain the Ni4Mo / NF catalyst.

[0033] Experimental Example 1: Morphological Characterization Analysis 1.1 SEM analysis was performed on the Ni4Mo / Ni(OH)2 / NF catalyst prepared in Example 1, the Ni / NF catalyst, Mo / NF catalyst prepared in Comparative Examples 1-5, and the Ni4Mo / NF catalyst. The results are as follows: Figures 2-4 As shown.

[0034] from Figures 2-4 As can be seen from the present invention, a dense and crack-free alloy film was successfully deposited on a nickel foam framework using cyclic voltammetry. The resulting Ni4Mo alloy film is composed of nanoscale spherical particles that are uniformly distributed on the nickel foam framework and are firmly bonded without cracks. In contrast, the Ni / NF and Mo / NF catalysts (Comparative Examples 1-2) obtained by depositing Ni and Mo separately on nickel foam also showed no cracks, but they did not form nanospheres like those in Ni4Mo / Ni(OH)2 / NF.

[0035] However, by using the constant current density method, at 1 A / cm 2 2 A / cm 2 and 3 A / cm 2 The Ni4Mo / NF catalysts prepared by electrodeposition at high current densities (Comparative Examples 3-5) have a large number of cracks on the surface of the Ni4Mo alloy film. This will cause the Ni4Mo alloy catalyst layer to fall off during the rapid bubble reaction in the subsequent hydrogen evolution reaction at high current densities, making it difficult for it to operate stably for a long time.

[0036] 1.2 The Ni4Mo / Ni(OH)2 / NF catalyst prepared in Example 1 above was subjected to EDS analysis, and the results are as follows: Figure 5 As shown.

[0037] from Figure 5As can be seen, the Mo, Ni and O elements are uniformly distributed on the surface of the Ni4Mo / Ni(OH)2 / NF catalyst, further confirming the successful synthesis of the Ni4Mo / Ni(OH)2 / NF catalyst.

[0038] 1.3 The Ni4Mo / Ni(OH)2 / NF catalyst prepared in Example 1 was analyzed by TEM and electron diffraction patterns. The results are as follows: Figures 6-7 As shown.

[0039] from Figures 6-7 As can be seen from the image, the Ni4Mo alloy on the surface of the Ni4Mo / Ni(OH)2 / NF catalyst is a dense thin film. The electron diffraction pattern shows a diffraction ring corresponding to the (121) crystal plane of Ni4Mo, which further confirms the successful synthesis of the Ni4Mo alloy on the catalyst surface.

[0040] 1.4 The Ni4Mo / Ni(OH)2 / NF catalyst prepared in Example 1 was subjected to HRTEM analysis to study the phase composition and structure of the Ni4Mo / Ni(OH)2 / NF catalyst surface. The results are shown in [Figure 1]. Figure 8 .

[0041] from Figure 8 As can be seen, lattice fringes with a spacing of 0.206 nm were found on the catalyst surface, corresponding to the (121) crystal plane of Ni4Mo. Furthermore, lattice fringes with a spacing of 0.215 nm were also found, corresponding to the (101) crystal plane of Ni(OH)2, consistent with the XRD characterization results. This indicates that Ni4Mo alloy and Ni(OH)2 coexist on the Ni4Mo / Ni(OH)2 / NF surface.

[0042] The above results confirm the successful synthesis of the Ni4Mo / Ni(OH)2 / NF catalyst.

[0043] 1.5 The Ni4Mo / Ni(OH)2 catalyst and nickel foam supported on the surface of the Ni4Mo / Ni(OH)2 / NF catalyst prepared in Example 1 were exfoliated by ultrasound to avoid signal interference from the nickel foam substrate. XRD patterns of the Ni4Mo / Ni(OH)2 were analyzed, and the results are as follows: Figure 9 As shown.

[0044] from Figure 9 As can be seen, two peaks belonging to the (121) and (312) crystal planes of Ni4Mo were found at 2-Theta = 43.5° and 74.7°, confirming the successful synthesis of the Ni4Mo alloy. At the same time, the (001) crystal plane belonging to Ni(OH)2 was also found at 2-Theta = 19.3°, proving the coexistence of the two substances.

[0045] 1.6 Raman spectroscopy was performed on the Ni4Mo / Ni(OH)2 / NF catalyst prepared in Example 1, the Ni / NF catalyst prepared in Comparative Example 1, and the Mo / NF catalyst prepared in Comparative Example 2. The results are as follows: Figure 10 As shown.

[0046] from Figure 10 As can be seen, Ni4Mo / Ni(OH)2 / NF exhibits several distinct characteristic peaks, related to Ni-O, Mo-O, and Mo=O bonds, respectively. The presence of Ni-O bonds further confirms the formation of Ni(OH)2 on the Ni4Mo / NF surface, while the Mo-O and Mo=O bonds may be related to the interaction between Ni(OH)2 and the Ni4Mo alloy. In contrast, Ni / NF and Mo / NF do not show similar Raman peaks, indicating that the simultaneous introduction of Ni and Mo sources during electrodeposition is crucial for the formation of this structure.

[0047] 1.7 The surface chemical states of the three groups of samples—the Ni4Mo / Ni(OH)2 / NF catalyst prepared in Example 1, the Ni / NF catalyst prepared in Comparative Example 1, and the Mo / NF catalyst prepared in Comparative Example 2—were further characterized using XPS. The results are as follows: Figure 11 As shown.

[0048] Figure 11 XPS spectroscopy confirmed the presence of Ni, Mo and O in the Ni4Mo / Ni(OH)2 / NF catalyst, consistent with the EDS elemental distribution results above.

[0049] Furthermore, Figure 11 Figure b shows the XPS spectra of Mo 3d in two groups of samples: Ni4Mo / Ni(OH)2 / NF and Mo / NF. These spectra can be fitted to three sets of bimodal peaks. For Ni4Mo / NF, the peaks at 232.11 eV and 235.29 eV belong to Mo. 6+ 3D 5 / 2 and 3D 3 / 2 The peaks at 229.97 eV and 233.19 eV belong to Mo. 5+ 3D 5 / 2 and 3D 3 / 2 The peaks at 227.94 eV and 230.64 eV belong to Mo. 4+ 3D 5 / 2 and 3D 3 / 2 Compared to Mo / NF, all peaks in Ni4Mo / Ni(OH)2 / NF shift towards directions with lower electron binding energies.

[0050] Figure 11Figure c shows the XPS spectra of Ni 2p in two groups of samples: Ni4Mo / Ni(OH)2 / NF and Ni / NF. These spectra can be fitted to three sets of doublets and a pair of satellite peaks. For Ni4Mo / Ni(OH)2 / NF, the peaks at 856.84 eV and 874.66 eV belong to Ni. 3+ 2p 3 / 2 and 2p 1 / 2 The peaks at 855.59 eV and 873.14 eV belong to Ni. 2+ 2p 3 / 2 and 2p 1 / 2 The peaks at 852.36 eV and 869.68 eV belong to Ni. 0 2p 3 / 2 and 2p 1 / 2 The peaks at 861.31 eV and 879.32 eV are satellite peaks. Compared to Ni / NF, all peaks in Ni4Mo / NF shift towards directions with higher electron binding energies.

[0051] Figure 11 Figure d shows the XPS spectra of the O 1s of three samples: Ni4Mo / Ni(OH)2 / NF, Ni / NF, and Mo / NF. The Ni4Mo / Ni(OH)2 / NF sample can be decomposed into three surface components at 530.55 eV, 531.6 eV, and 534.38 eV, belonging to lattice oxygen (MO), hydroxyl groups (-OH), and adsorbed water molecules (H2O), respectively. It can be observed that Ni4Mo / Ni(OH)2 / NF has the highest hydroxyl group content, which further confirms the formation of Ni(OH)2 on the Ni4Mo / Ni(OH)2 / NF surface.

[0052] Experimental Example 2: Electrocatalytic Activity Analysis The electrocatalytic activity of the Ni4Mo / Ni(OH)2 / NF catalyst prepared in Example 1, the Ni / NF catalyst prepared in Comparative Example 1, and the Mo / NF catalyst prepared in Comparative Example 2 was tested. The hydrogen evolution reaction (HER) performance of the prepared catalysts was evaluated in a 1 M KOH electrolyte using a typical three-electrode system. Linear sweep voltammetry curves are shown below. Figure 12 As shown.

[0053] from Figure 12 As can be seen, the Ni4Mo / Ni(OH)2 / NF catalyst exhibits excellent HER activity as an electrode, achieving 10, 100, 500 and 1000 mA cm⁻¹ activity. -2The overpotentials (η) required for the current densities were 6, 90, 180, and 242 mV, respectively. These overpotentials were significantly lower than those achieved with Ni / NF catalysts (96, 262, 359, and 419 mV) as electrodes, while for the deposition of metallic molybdenum solely on NF, Mo / NF catalysts as electrodes achieved 10, 100, and 500 mA cm⁻¹. -2 The overpotentials (η) required for the current densities are 218, 326 and 439 mV, respectively, and their HER activities are comparable to those of pure nickel foam NF electrodes (242, 382 and 468 mV).

[0054] The above results indicate that electrodepositing Ni or Mo alone on a nickel foam substrate results in extremely limited improvement in HER activity. However, simultaneous deposition of Ni and Mo significantly enhances HER activity.

[0055] Furthermore, the Tafel slope was extrapolated from the LSV curves; a lower Tafel slope indicates that the catalyst has faster HER reaction kinetics, as shown in the results. Figure 13 As shown.

[0056] from Figure 13 As can be seen, the Tafel slope of Ni4Mo / Ni(OH)2 / NF is only 88 mV dec. -1 Significantly lower than Mo / NF (112 mV dec) -1 ), Ni / NF (139 mV dec) -1 ) and NF (149 mV dec -1 This further demonstrates the excellent HER reaction kinetics of Ni4Mo / Ni(OH)2 / NF, with a Tafel slope between 40 and 120, indicating that its HER process follows the Volmer-Heyrovsky mechanism, where the Heyrovsky step is the rate-determining step. Similarly, the exchange current density (j0) extrapolated from the Tafel plot shows that Ni4Mo / Ni(OH)2 / NF has the highest value. A higher exchange current density indicates a faster intrinsic kinetic rate of the electrode reaction and higher catalyst activity, further confirming its optimal reaction kinetics.

[0057] Furthermore, electrochemical impedance spectroscopy (EIS) was used to study charge transfer characteristics, and the results are shown in [Figure number missing]. Figure 14 .

[0058] like Figure 14According to the equivalent circuit model, the fitted charge transfer resistance (Rct) of the Ni4Mo / NF electrode (11 Ω) is significantly lower than that of Ni / NF (348 Ω), Mo / NF (517 Ω), and NF (5517 Ω). The lowest charge transfer resistance of Ni4Mo / Ni(OH)2 / NF indicates that it has the fastest charge transfer, which is one of the reasons for its best HER activity.

[0059] Simultaneously, its electrochemical double-layer capacitance (Cdl) and intrinsic activity were tested, and the results are shown in […]. Figure 15 .

[0060] from Figure 15 As can be seen from the data, the electrochemical double-layer capacitance (Cdl) of the Ni4Mo / Ni(OH)2 / NF electrode is 2.1 mFcm. -2 ), higher than Ni / NF (1.3 mF cm), -2 ), Mo / NF (0.9 mF cm -2 ) and NF (1.2 mF cm -2 The highest Cdl value indicates that the Ni4Mo / Ni(OH)2 / NF electrode has the largest electrochemically active surface area, suggesting that the Ni4Mo / NF electrode has a greater advantage in HER kinetics, which is one of the reasons for its optimal HER activity. Further investigation of the intrinsic activity of the prepared catalyst, using the corresponding Cdl values ​​to estimate the electrochemically active surface area (ECSA), and normalizing the LSV curves using ECSA data, reveals that the Ni4Mo / Ni(OH)2 / NF electrode exhibits significantly higher intrinsic activity.

[0061] Finally, the Ni4Mo / Ni(OH)2 / NF electrode was tested at an industrial-grade high current density (500 mA cm⁻¹). -2 A long-term stability test was conducted, and the results are as follows: Figure 16 As shown.

[0062] from Figure 16 As can be seen from the data, the Ni4Mo / Ni(OH)2 / NF electrode exhibits excellent stability under industrial-grade high current density conditions, at 500 mA cm⁻¹. -2 After 500 hours of stable operation at a given current density, the catalyst structure remained intact, and the nanosphere structure on the catalyst surface was clearly visible. During continuous operation for 500 hours, the overpotential showed almost no increase, demonstrating excellent electrocatalytic stability and potential for industrial application.

[0063] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a Ni4Mo / Ni(OH)2 / NF catalyst, characterized in that, Includes the following steps: (1) The nickel foam is ultrasonically cleaned to obtain pretreated nickel foam; (2) Dissolve trisodium citrate, molybdenum source and nickel source together in water to obtain a reaction solution; (3) Using pretreated nickel foam as the working electrode, platinum sheet as the counter electrode, Ag / AgCl as the reference electrode, and reaction solution as the electrolyte, electrodeposition was performed by voltammetric cyclic scanning method to obtain Ni4Mo / Ni(OH)2 / NF catalyst.

2. The preparation method of the Ni4Mo / Ni(OH)2 / NF catalyst as described in claim 1, characterized in that, Step (1) includes the following steps: ultrasonically clean the nickel foam in hydrochloric acid, acetone, anhydrous ethanol and water for 10-20 min respectively, and then dry it under vacuum to obtain pretreated nickel foam.

3. The preparation method of the Ni4Mo / Ni(OH)2 / NF catalyst as described in claim 2, characterized in that, The molar concentration of the hydrochloric acid is 0.8~1.2 M.

4. The preparation method of the Ni4Mo / Ni(OH)2 / NF catalyst as described in claim 1, characterized in that, The molybdenum source in step (2) is sodium molybdate, ammonium molybdate, or molybdenum trioxide; the nickel source is nickel nitrate, nickel sulfate, or nickel chloride; and the mass ratio of trisodium citrate, molybdenum source, and nickel source is 10:(0.4~0.6):(0.5~0.7).

5. The preparation method of the Ni4Mo / Ni(OH)2 / NF catalyst as described in claim 4, characterized in that, In step (2), the molybdenum source is sodium molybdate; the nickel source is nickel nitrate; and the mass ratio of trisodium citrate, molybdenum source, and nickel source is 10:0.5:0.

6.

6. The preparation method of the Ni4Mo / Ni(OH)2 / NF catalyst as described in claim 1, characterized in that, Step (3) uses the cyclic voltammetric scanning method for electrodeposition, which includes the following steps: performing 90 to 110 cyclic voltammetric scans on an electrochemical workstation at a scan rate of 95 to 105 mV / s within a voltage range of -6 to -1 V relative to the reference electrode.

7. The preparation method of the Ni4Mo / Ni(OH)2 / NF catalyst as described in claim 6, characterized in that, Step (3) uses the cyclic voltammetric scanning method for electrodeposition, which includes the following steps: performing 100 cycles of cyclic voltammetric scanning at a scan rate of 100 mV / S on an electrochemical workstation within a voltage range of -4 to -2 V relative to the reference electrode.

8. The Ni4Mo / Ni(OH)2 / NF catalyst prepared by the preparation method according to any one of claims 1 to 7.

9. The application of the Ni4Mo / Ni(OH)2 / NF catalyst according to claim 8 in electrocatalytic hydrogen evolution.

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