High-activity catalyst for hydrogen production by electrolysis of water and preparation method and application thereof

Abstract

The application provides a high-activity catalyst for electrolysis of water to produce hydrogen and a preparation method and application thereof. Specifically, the catalyst for electrolysis of water to produce hydrogen comprises a carbon sintered body carrier and an active component loaded on the surface and inside of the carbon sintered body carrier, wherein the active component comprises nickel molybdenum nitride (NiMoN), cobalt phosphide (CoP) and cerium oxide, and the catalyst has a porous structure. The catalyst according to the application is low in cost, high in activity and good in stability, can effectively reduce the cost of electrolysis of water to produce hydrogen, and improves the hydrogen production efficiency.

Description

Technical Field

[0001] This invention belongs to the field of electrolytic materials technology for water electrolysis, specifically relating to a highly active catalyst for hydrogen production from water electrolysis, its preparation method, and its application. Background Technology

[0002] With the global energy crisis and environmental pollution worsening, the development of clean and sustainable alternative energy sources has become an urgent need for human societal development. Hydrogen energy, as a clean energy source with high energy density, combustion products consisting only of water, and recyclability, is considered the most promising fossil fuel alternative of the 21st century.

[0003] Electrolysis of water is one of the most promising green hydrogen production technologies. Its principle involves using an external electric field to drive the decomposition of water molecules into hydrogen (hydrogen evolution reaction at the cathode, HER) and oxygen (oxygen evolution reaction at the anode, OER). However, the kinetics of water electrolysis are slow, especially the HER reaction, which requires a high overpotential to achieve the industrially required current density. Therefore, highly efficient catalysts are essential to lower the reaction energy barrier. Currently, commercial water electrolysis for hydrogen production widely uses platinum (Pt)-based catalysts (such as Pt / C), whose HER catalytic activity is close to the theoretical limit. However, Pt is expensive, resulting in high costs for water electrolysis and limiting the large-scale application of this technology.

[0004] To address the cost issue of precious metal catalysts, researchers have turned their attention to transition metal-based catalysts (such as Ni, Co, Mo, and V). These materials are abundant in the Earth's crust, inexpensive, and can achieve excellent HER catalytic performance through structural design, compositional regulation, or heterostructure construction. Currently reported transition metal HER catalysts mainly include oxides, hydroxides, sulfides, phosphides, and nitrides.

[0005] Despite significant progress in transition metal-based catalysts, existing technologies still face several challenges. First, the HER activity of single-component transition metal catalysts remains lower than that of Pt / C, especially exhibiting higher overpotentials at high current densities, making them unsuitable for industrial electrolyzers. Furthermore, during long-term electrolysis, transition metal catalysts are prone to oxidation, dissolution, or agglomeration, leading to activity degradation. Additionally, some catalysts require high temperature and pressure, inert gas protection, or complex template-assisted synthesis, resulting in high preparation costs, poor reproducibility, and difficulties in large-scale production.

[0006] Therefore, it is of great significance to develop a low-cost, highly active and stable multi-component synergistic catalyst. Summary of the Invention

[0007] Based on the technical problems described above, one objective of this invention is to provide a highly active catalyst for hydrogen production through water electrolysis, its preparation method, and its application. This catalyst uses a carbon sintered body as a support, loading nickel-molybdenum nitride (NiMoN), cobalt phosphide (CoP), and cerium oxide (SeO2). Through the synergistic effect of these three components, it achieves high HER activity, excellent stability, and low cost, solving the problems of insufficient activity and poor stability of existing transition metal catalysts. Another objective of this invention is to provide a method for preparing the above-mentioned catalyst. This method is simple, operates under mild conditions, has good reproducibility, and enables large-scale production of the catalyst. A further objective of this invention is to provide applications for the above-mentioned catalyst. This catalyst can be used for hydrogen production through water electrolysis under alkaline, acidic, or neutral conditions, and is particularly suitable for industrial-grade high-current-density water electrolysis systems, significantly reducing hydrogen production costs.

[0008] Specifically, according to one aspect of the present invention, a method for preparing a catalyst for hydrogen production by water electrolysis is provided, the method comprising the following steps in sequence: (1) adding nickel nitrate, ammonium molybdate, cobalt chloride, sodium hypophosphite, glucose and cerium nitrate sequentially to a mixed solvent of deionized water and ethylene glycol, and stirring thoroughly to form a precursor solution, wherein the weight ratio of nickel nitrate, ammonium molybdate, cobalt chloride, sodium hypophosphite, glucose and cerium nitrate is 1 : 0.59-0.67 : 0.48-0.60 : 0.40-0.60 : 1.54-2.34 : 0.08-0.43, and the ratio of the total weight of nickel nitrate, ammonium molybdate, cobalt chloride, sodium hypophosphite, glucose and cerium nitrate to the weight of the mixed solvent is in the range of 0.2:1-0.3:1; (2) the precursor solution is transferred to a stainless steel reactor with a polytetrafluoroethylene liner and reacted at 180-240°C, preferably 200-220°C, for 12-18 hours, preferably 14-15 hours, to generate a hydrothermal product; (3) the hydrothermal product is placed in a tube furnace and kept at 600-800°C, preferably 650-730°C, for 3-5 hours under a nitrogen atmosphere to obtain a calcined product; (4) the calcined product is ground to obtain the catalyst.

[0009] According to certain preferred embodiments of the present invention, the weight ratio of deionized water to ethylene glycol in the mixed solvent is 2:1 to 1:2.

[0010] According to certain preferred embodiments of the present invention, in step (1), nickel nitrate and ammonium molybdate are added to a mixed solvent of deionized water and ethylene glycol and stirred thoroughly to dissolve; then cobalt chloride and sodium hypophosphite are added and stirred thoroughly to dissolve; subsequently, glucose and cerium nitrate are added and stirred thoroughly to dissolve to form a precursor solution.

[0011] According to another aspect of the present invention, a catalyst for hydrogen production by water electrolysis prepared according to the preparation method described above is provided, the catalyst comprising a carbon sintered support and active components supported on the surface and interior of the carbon sintered support, the active components comprising nickel-molybdenum nitride (NiMoN), cobalt phosphide (CoP), and cerium oxide, wherein the catalyst has a porous structure.

[0012] According to certain preferred embodiments of the present invention, the carbon sintered body is a sintering product of glucose.

[0013] According to certain preferred embodiments of the present invention, the average pore size of the porous structure is in the range of 5-30 nm, preferably 8-20 nm.

[0014] According to certain preferred embodiments of the present invention, the nickel-molybdenum nitride (NiMoN), cobalt phosphide (CoP) and cerium oxide are uniformly dispersed on the surface and inside the carbon sintered body carrier.

[0015] According to another aspect of the present invention, the above-described catalyst is provided for use in the electrolysis of water to produce hydrogen.

[0016] According to certain preferred embodiments of the invention, the catalyst is coated on the working electrode.

[0017] According to certain preferred embodiments of the present invention, the working electrode is nickel foam. Attached Figure Description

[0018] The accompanying drawings are provided in this specification to more clearly explain the technical solutions of the present invention; however, the art is not limited thereto.

[0019] Figure 1 The image shows a transmission electron microscope (SEM) image of the catalyst for hydrogen production by water electrolysis prepared according to Example 1 of the present invention.

[0020] Figure 2 The image shows an X-ray diffraction (XRD) pattern of the catalyst for hydrogen production by water electrolysis prepared according to Example 1 of the present invention. Detailed Implementation

[0021] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. It will be understood that other embodiments may be implemented without departing from the scope or spirit of the invention. Therefore, the following detailed description is non-limiting.

[0022] Unless otherwise specified, all figures used in this specification to represent characteristic dimensions, quantities, and physical properties should be understood to be modified by the term "about" in all cases. Therefore, unless otherwise stated, the numerical parameters listed in the foregoing specification are approximations, and those skilled in the art can appropriately modify these approximations to obtain the desired properties using the teachings disclosed herein.

[0023] As mentioned above, existing catalysts in the field of hydrogen production through water electrolysis face the following problems: First, commercial precious metal catalysts (such as Pt / C) are scarce in the Earth's crust and expensive, making large-scale application difficult; second, existing transition metal-based catalysts (such as single phosphides and nitrides) have insufficient activity, high overpotentials at high current densities, and are prone to oxidation, dissolution, or aggregation during long-term electrolysis, resulting in poor stability; third, the synergistic mechanism between components in multi-component catalysts is unclear, making it difficult to achieve a balance between activity and stability; fourth, the preparation processes of some catalysts are complex and demanding (such as high temperature and high pressure, complex templates), resulting in high costs and poor reproducibility, which is not conducive to large-scale production. This invention aims to solve the above technical problems.

[0024] Specifically, according to one aspect of the present invention, a method for preparing a catalyst for hydrogen production by water electrolysis is provided, the preparation method comprising the following steps in sequence: (1) adding nickel nitrate, ammonium molybdate, cobalt chloride, sodium hypophosphite, glucose and cerium nitrate sequentially to a mixed solvent of deionized water and ethylene glycol, and stirring thoroughly to form a precursor solution, wherein the weight ratio of nickel nitrate, ammonium molybdate, cobalt chloride, sodium hypophosphite, glucose and cerium nitrate is 1 : 0.59-0.67 : 0.48-0.60 : 0.40-0.60 : 1.54-2.34 : 0.08-0.43, and the ratio of the total weight of nickel nitrate, ammonium molybdate, cobalt chloride, sodium hypophosphite, glucose and cerium nitrate to the weight of the mixed solvent is in the range of 0.2:1-0.3:1; (2) the precursor solution is transferred to a stainless steel reactor with a polytetrafluoroethylene liner and reacted at 180-240°C for 12-18 hours to generate a hydrothermal product; (3) the hydrothermal product is placed in a tube furnace and kept at 600-800°C for 3-5 hours under nitrogen atmosphere protection to obtain a calcined product; (4) the calcined product is ground to obtain the catalyst.

[0025] Specifically, in step (1) above, nickel nitrate (Ni(NO3)2•6H2O) and ammonium molybdate ((NH4)6Mo7O) are added sequentially to the mixed solvent of deionized water and ethylene glycol. 24 • 4H2O), cobalt chloride (CoCl2•6H2O), sodium hypophosphite (NaH2PO2•H2O), glucose (C6H 12O6) and cerium nitrate (Ce(NO3)3•6H2O) are magnetically stirred at room temperature for 30-60 minutes until all solutes are completely dissolved to form a clear and transparent precursor solution.

[0026] The amounts of each raw material used meet the following conditions: the weight ratio of nickel nitrate, ammonium molybdate, cobalt chloride, sodium hypophosphite, glucose, and cerium nitrate is 1:0.59-0.67:0.48-0.60:0.40-0.60:1.54-2.34:0.08-0.43; the weight ratio of the total weight of nickel nitrate, ammonium molybdate, cobalt chloride, sodium hypophosphite, glucose, and cerium nitrate to the weight of the mixed solvent is 0.2:1-0.3:1; and in the mixed solvent, the weight ratio of deionized water to ethylene glycol is 2:1-1:2, preferably 1:1. The addition of ethylene glycol can improve the solubility of the metal salt and inhibit particle agglomeration during hydrothermal processes.

[0027] Furthermore, the preferred order of adding raw materials in step (1) is as follows: first add nickel nitrate and ammonium molybdate, and stir for 15-30 minutes until completely dissolved; then add cobalt chloride and sodium hypophosphite, and stir for 15-30 minutes until completely dissolved; finally add glucose and cerium nitrate, and stir for 15-30 minutes until completely dissolved. This order can avoid premature precipitation reactions between different metal salts and ensure the homogeneity of the precursor solution.

[0028] In step (2) above, the precursor solution prepared in step (1) is transferred to a stainless steel reactor with a polytetrafluoroethylene liner (liner volume is 50-200 mL, solution filling ratio is 70%-80%), sealed, and placed in an oven for hydrothermal reaction at 180-240℃, preferably 200-220℃, for 12-18 hours, preferably 14-15 hours. After the reaction is completed, the oven is closed, and the mixture is allowed to cool naturally to room temperature. The liner is then removed, and the black precipitate at the bottom (hydrothermal product) is collected.

[0029] The mechanism of the hydrothermal reaction is as follows. Under high temperature and pressure, ethylene glycol acts as a reducing agent to partially reduce Ni. 2+ Co 2+ Reduced to lower valence metal ions (such as...) , Glucose undergoes partial carbonization to form carbon-like spheres. Metal ions are adsorbed onto the surface of these carbon-like spheres through coordination or electrostatic interactions. Sodium hypophosphite provides PO4. 3- Ammonium molybdate provides MoO4 2- Ultimately, a complex hydrothermal product is formed, consisting of "metal ions-carbon-like spheres-phosphorus / molybdate".

[0030] In step (3) above, the hydrothermal product collected in step (2) is washed 3-5 times alternately with deionized water and anhydrous ethanol (centrifugation speed 8000-10000 rpm each time for 5-10 minutes) to remove unreacted raw materials and impurities. Then, it is vacuum dried at 60-80℃ for 12-24 hours to obtain a dried hydrothermal product powder. Subsequently, the dried powder is placed in a tube furnace and heated under a nitrogen atmosphere (nitrogen purity ≥ 99.999%, flow rate 50-100 mL•min). -1 Under protection, at 5-10℃•min -1 The heating rate is increased to 600-800℃, preferably 650-730℃, and held for 3-5 hours to carry out the calcination reaction. After calcination, a nitrogen atmosphere is maintained until the tube furnace cools to room temperature, and the black calcined product is collected.

[0031] The mechanism of the calcination reaction is as follows: Glucose is completely carbonized to form a carbon sintered body support, while releasing gases such as CO2 and H2O, forming a porous structure; Ni 2+ MoO4 2- It reacts with nitrogen to produce NiMoN (reaction formula: Ni 2+ + MoO4 2- + NH3 → NiMoN + H2O + O2, Produced by the decomposition of ammonium molybdate); Co 2+ It reacts with PH3 produced by the decomposition of sodium hypophosphite to generate CoP (reaction formula: Ce 3+ Oxidized to Ce 4+ CeO2 is formed (reaction formula: CeO2) 3+ + O2 → CeO2, where O2 comes from trace amounts of air remaining in the hydrothermal products.

[0032] In step (4) above, the calcined product obtained in step (3) is placed in an agate mortar and ground for 30-60 minutes, or ground using a planetary ball mill to obtain catalyst powder, which is the high-activity catalyst for hydrogen production by water electrolysis of the present invention.

[0033] According to another aspect of the present invention, a highly active catalyst for hydrogen production by water electrolysis is provided, comprising a carbon sintered support and an active component supported on and within the surface of the support. The active component consists of nickel-molybdenum nitride (NiMoN), cobalt phosphide (CoP), and cerium oxide (CeO2), all uniformly dispersed within the carbon sintered body. The catalyst has a porous structure with an average pore size of 5-30 nm, preferably 8-20 nm, and a specific surface area of ​​80-200 m². 2 •g -1 Preferred 120-180 m2 •g -1 .

[0034] Furthermore, the carbon sintered body is a sintering product of glucose, and its preparation process is as follows: when glucose is calcined at 600-800℃ under a nitrogen atmosphere, a carbonization reaction occurs to form graphitized carbon, while releasing... , Gases are mixed to form a porous structure. The carbon sintered body provides support for the active components, and also provides high electrical conductivity and good chemical stability, which can promote electron transport and inhibit the aggregation of active components.

[0035] Furthermore, the mass ratio of nickel-molybdenum nitride (NiMoN), cobalt phosphide (CoP), and cerium oxide (CeO2) in the active components is 1:0.3-0.8:0.05-0.3, preferably 1:0.4-0.6:0.1-0.2. This ratio can be controlled by adjusting the amounts of nickel nitrate, ammonium molybdate, cobalt chloride, sodium hypophosphite, and cerium nitrate in the precursor solution to ensure that the three form a uniform heterogeneous structure and achieve synergistic effects.

[0036] Furthermore, scanning electron microscopy (SEM) observation revealed that the catalyst exhibits a porous, blocky structure, with the carbon sintered body forming a continuous three-dimensional network. The nickel-molybdenum nitride (NiMoN), cobalt phosphide (CoP), and cerium oxide are uniformly dispersed on the surface and within the carbon sintered body support.

[0037] According to another aspect of the present invention, the above-described catalyst is provided for use in the electrolysis of water to produce hydrogen.

[0038] Preferably, the catalyst is coated on the working electrode. Furthermore, preferably, the working electrode is nickel foam.

[0039] Specifically, for example, catalyst powder, conductive agent (such as acetylene black, carbon nanotubes), and binder (such as Nafion solution, 5% by mass) are mixed in a mass ratio of 8:1:1, and an appropriate amount of anhydrous ethanol is added. The mixture is then ultrasonically dispersed for 30-60 minutes to form a uniform catalyst slurry. The catalyst slurry is then uniformly coated onto a substrate (such as nickel foam, with an area of ​​1×1 cm²). 2 The surface coating amount is 0.5-2 mg / cm². -2 Then, the catalyst-supported working electrode is obtained by vacuum drying at 60-80℃ for 12-24 hours. The preferred substrate is nickel foam (1-2 mm thick, 90%-95% porosity), whose high conductivity and porous structure promote electron transport and electrolyte permeation.

[0040] The advantages of the highly active catalyst for hydrogen production by water electrolysis according to the present invention are as follows: First, it has a significant cost advantage. Using abundant and inexpensive transition metals such as nickel, molybdenum, and cobalt, as well as glucose, as raw materials, and prepared using conventional processes such as hydrothermal reaction and calcination, the cost is reduced by more than 80% compared to traditional platinum-based catalysts, and it is easy to scale up production. Second, it has high catalytic activity, reaching 10 mA / cm² in 1M KOH electrolyte. 2 At current density, the overpotential is as low as 48-65 mV, and the Tafel slope is 56.7-65.3 mV•dec. -1 It is superior to most non-precious metal catalysts. Third, it has strong stability. After 500 hours of continuous electrolysis, the current density retention rate is over 90%, and it has strong resistance to impurity poisoning, maintaining high catalytic performance for a long time.

[0041] The present invention will now be described in more detail with reference to embodiments. It should be noted that these descriptions and embodiments are intended to facilitate understanding of the present invention and are not intended to limit the invention.

[0042] Example

[0043] In this invention, unless otherwise specified, all reagents used are commercially available products and are used directly without further purification. Furthermore, "%" refers to "weight %" and "parts" refers to "parts by weight".

[0044] Table 1 below lists specific information about the raw materials used in the embodiments and comparative examples of the present invention.

[0045]

[0046] Table 2 below lists specific information about the experimental equipment used in the embodiments and comparative examples of the present invention.

[0047]

[0048] Example 1: Preparation of a highly active catalyst for hydrogen production by water electrolysis

[0049] Preparation of precursor solution

[0050] Weigh out 1.0 g nickel nitrate, 0.63 g ammonium molybdate, 0.54 g cobalt chloride, 0.50 g sodium hypophosphite, 1.94 g glucose, and 0.25 g cerium nitrate (the weight ratio of each raw material is 1:0.63:0.54:0.50:1.94:0.25). Then, measure out 10 g deionized water and 10 g ethylene glycol (weight ratio 1:1), mix them thoroughly, and pour them into a 500 mL beaker. First, add nickel nitrate and ammonium molybdate, and stir magnetically for 15 minutes until completely dissolved; then add cobalt chloride and sodium hypophosphite, and continue stirring for 15 minutes until dissolved; finally, add glucose and cerium nitrate, and stir for 15 minutes to obtain a clear and transparent precursor solution.

[0051] The precursor solution was transferred to a 50 mL stainless steel reactor lined with polytetrafluoroethylene (PTFE) (75% filling ratio), sealed, and placed in an oven at 210 °C for 14.5 hours. After the reaction was completed, the reactor was allowed to cool naturally to room temperature. The liner was removed, and the black precipitate at the bottom was collected and washed four times each with deionized water and anhydrous ethanol (centrifuged at 9000 rpm for 8 minutes).

[0052] The washed precipitate was then vacuum dried at 70°C for 18 hours to obtain a dry powder. The powder was placed in a tube furnace and nitrogen gas was introduced (flow rate 80 mL / min). -1 ), at 8℃•min -1 The heating rate was increased to 690℃, and the temperature was maintained for 4 hours. After calcination, the mixture was cooled to room temperature, and the black calcined product was collected.

[0053] The calcined product was ground in an agate mortar for 45 minutes to obtain catalyst powder (denoted as Cat-1).

[0054] The morphology of Cat-1 was studied using scanning electron microscopy (SEM). Figure 1 The image shown is a transmission electron microscope (SEM) image of catalyst Cat-1. Figure 1 As described above, the catalyst Cat-1 has a porous structure.

[0055] In addition, a D8 Advance XRD instrument (Cu Kα rays, λ=0.15406 nm, scanning range 2θ=10°-70°, scanning rate 5°•min) was used. -1 Phase analysis was performed on catalyst Cat-1. Figure 2 The X-ray diffraction (XRD) pattern of catalyst Cat-1 is shown. Figure 2As shown in the XRD patterns, 2θ = 31.6°, 36.5°, 38.9°, 44.6°, 50.6° and 61.9° correspond to the (100), (002), (101), (102), (110) and (201) crystal planes of hexagonal nickel-molybdenum nitride (NiMoN) (PDF#76-1877); 2θ = 31.6°, 36.5° and 48.7° correspond to the (111), (200) and (220) crystal planes of cobalt phosphide (CoP) (PDF#65-1454); 2θ = 28.6°, 33.1° and 47.5° correspond to the (111), (200) and (220) crystal planes of cerium oxide (CeO2) (PDF#34-0394). The XRD pattern shows that the catalyst Cat-1 contains NiMoN, CoP and CeO2.

[0056] Example 2: Catalyst preparation with adjusted mixed solvent ratio

[0057] Compared with Example 1, only the weight ratio of deionized water to ethylene glycol in the mixed solvent was changed to 2:1 (13.3g deionized water + 6.7g ethylene glycol, 20g total solvent), while other steps and parameters remained unchanged, to obtain catalyst powder (denoted as Cat-2).

[0058] The morphology of Cat-2 was studied using scanning electron microscopy (SEM) in a manner similar to that of Example 1. The results showed that Cat-2 had similar morphological characteristics to Cat-1, exhibiting a porous structure.

[0059] Furthermore, the phase composition of catalyst Cat-2 was analyzed in a manner similar to that of Example 1. The results showed that the XRD diffraction pattern of catalyst Cat-2 was similar to that of catalyst Cat-1, indicating that catalyst Cat-2 simultaneously contains NiMoN, CoP, and CeO2.

[0060] Example 3: Preparation of catalyst with adjusted hydrothermal temperature

[0061] Compared with Example 1, only the hydrothermal temperature was adjusted to 200°C and the holding time was adjusted to 15 hours, while other steps and parameters remained unchanged, to obtain catalyst powder (denoted as Cat-3).

[0062] The morphology of Cat-3 was studied using scanning electron microscopy (SEM) in a manner similar to that of Example 1. The results showed that Cat-3 had similar morphological characteristics to Cat-1 and possessed a porous structure.

[0063] Furthermore, the phase composition of catalyst Cat-3 was analyzed in a manner similar to that of Example 1. The results showed that the XRD diffraction pattern of catalyst Cat-3 was similar to that of catalyst Cat-1, indicating that catalyst Cat-3 simultaneously contains NiMoN, CoP, and CeO2.

[0064] Example 4: Preparation of catalyst with adjusted calcination temperature

[0065] Compared with Example 1, only the calcination temperature was adjusted to 730°C and the holding time was adjusted to 3 hours, while other steps and parameters remained unchanged, to obtain catalyst powder (denoted as Cat-4).

[0066] The morphology of Cat-4 was studied using scanning electron microscopy (SEM) in a manner similar to that of Example 1. The results showed that Cat-4 had similar morphological characteristics to Cat-1, exhibiting a porous structure.

[0067] Furthermore, the phase composition of catalyst Cat-4 was analyzed in a manner similar to that of Example 1. The results showed that the XRD diffraction pattern of catalyst Cat-4 was similar to that of catalyst Cat-1, indicating that catalyst Cat-4 simultaneously contains NiMoN, CoP, and CeO2.

[0068] Example 5: Catalyst preparation with adjusted cerium nitrate dosage

[0069] Compared with Example 1, only the amount of cerium nitrate was adjusted to 0.08g (the weight ratio of each raw material was 1:0.63:0.54:0.50:1.94:0.08), while other steps and parameters remained unchanged, to obtain catalyst powder (denoted as Cat-5).

[0070] The morphology of Cat-5 was studied using scanning electron microscopy (SEM) in a manner similar to that of Example 1. The results showed that Cat-5 had similar morphological characteristics to Cat-1, exhibiting a porous structure.

[0071] Furthermore, the phase composition of catalyst Cat-5 was analyzed in a manner similar to that of Example 1. The results showed that the XRD diffraction pattern of catalyst Cat-5 was similar to that of catalyst Cat-1, indicating that catalyst Cat-5 simultaneously contains NiMoN, CoP, and CeO2.

[0072] Example 6: Catalyst preparation with adjusted cerium nitrate dosage

[0073] Compared with Example 1, only the amount of cerium nitrate was adjusted to 0.43g (the weight ratio of each raw material was 1:0.63:0.54:0.50:1.94:0.43), while other steps and parameters remained unchanged, to obtain catalyst powder (denoted as Cat-6).

[0074] The morphology of Cat-6 was studied using scanning electron microscopy (SEM) in a manner similar to that of Example 1. The results showed that Cat-6 had similar morphological characteristics to Cat-1, exhibiting a porous structure.

[0075] Furthermore, the phase composition of catalyst Cat-6 was analyzed in a manner similar to that of Example 1. The results showed that the XRD diffraction pattern of catalyst Cat-6 was similar to that of catalyst Cat-1, indicating that catalyst Cat-6 simultaneously contains NiMoN, CoP, and CeO2.

[0076] Comparative Example 1:

[0077] Compared with Example 1, the raw materials were 1.0 g nickel nitrate, 0.4 g ammonium molybdate, 0.54 g cobalt chloride, 0.50 g sodium hypophosphite, 1.94 g glucose, and 0.25 g cerium nitrate (the weight ratio of each raw material was 1:0.4:0.54:0.50:1.94:0.25), and other steps and parameters remained unchanged, resulting in catalyst powder (denoted as Cat-C1).

[0078] The morphology of Cat-C1 was studied using scanning electron microscopy (SEM) in a manner similar to that of Example 1. The results showed that Cat-C1 has similar morphological characteristics to Cat-1 and has a porous structure.

[0079] Furthermore, the catalyst Cat-C1 was subjected to phase analysis in a manner similar to that of Example 1. The resulting XRD patterns showed that 2θ = 31.6°, 36.5°, and 48.7° corresponded to the (111), (200), and (220) crystal planes of cobalt phosphide (CoP) (PDF#65-1454); and 2θ = 28.6°, 33.1°, and 47.5° corresponded to the (111), (200), and (220) crystal planes of cerium oxide (CeO2) (PDF#34-0394). The XRD results indicated that the catalyst Cat-C1 contained both CoP and CeO2. However, the characteristic peaks such as 38.9° (101), 44.6° (102), and 50.6° (110) indicating the presence of NiMoN were absent.

[0080] Comparative Example 2:

[0081] Compared with Example 1, the raw materials were 1.0 g nickel nitrate, 0.63 g ammonium molybdate, 0.25 g cobalt chloride, 0.50 g sodium hypophosphite, 1.94 g glucose, and 0.25 g cerium nitrate (the weight ratio of each raw material was 1:0.63:0.25:0.50:1.94:0.25, and other steps and parameters remained unchanged, resulting in catalyst powder (denoted as Cat-C2).

[0082] The morphology of Cat-C2 was studied using scanning electron microscopy (SEM) in a manner similar to that of Example 1. The results showed that Cat-C2 has similar morphological characteristics to Cat-1 and has a porous structure.

[0083] Furthermore, the catalyst Cat-C2 was subjected to phase analysis in a manner similar to that of Example 1. The resulting XRD pattern showed that 2θ = 31.6°, 36.5°, 38.9°, 44.6°, 50.6°, and 61.9° corresponded to the (100), (002), (101), (102), (110), and (201) crystal planes of hexagonal nickel-molybdenum nitride (NiMoN) (PDF#76-1877); and 2θ = 28.6°, 33.1°, and 47.5° corresponded to the (111), (200), and (220) crystal planes of cerium oxide (CeO2) (PDF#34-0394). This XRD pattern indicates that the catalyst Cat-C2 contains both NiMoN and CeO2. However, characteristic peaks such as 48.7° (220) indicating the presence of cobalt phosphide (CoP) were absent.

[0084] Comparative Example 3:

[0085] Compared with Example 1, the raw materials were 1.0 g nickel nitrate, 0.63 g ammonium molybdate, 0.54 g cobalt chloride, 0.50 g sodium hypophosphite, 1.94 g glucose, and 0.05 g cerium nitrate (the weight ratio of each raw material was 1:0.63:0.54:0.50:1.94:0.05), and other steps and parameters remained unchanged, resulting in catalyst powder (denoted as Cat-C3).

[0086] The morphology of Cat-C3 was studied using scanning electron microscopy (SEM) in a manner similar to that of Example 1. The results showed that Cat-C3 had similar morphological characteristics to Cat-1, exhibiting a porous structure.

[0087] Furthermore, the catalyst Cat-C3 was subjected to phase analysis in a manner similar to that of Example 1. The resulting XRD pattern showed that 2θ = 31.6°, 36.5°, 38.9°, 44.6°, 50.6°, and 61.9° corresponded to the (100), (002), (101), (102), (110), and (201) crystal planes of hexagonal nickel-molybdenum nitride (NiMoN) (PDF#76-1877); and 2θ = 31.6°, 36.5°, and 48.7° corresponded to the (111), (200), and (220) crystal planes of cobalt phosphide (CoP) (PDF#65-1454). This XRD pattern indicates that the catalyst Cat-C3 contains both NiMoN and CoP. However, the characteristic peaks of 28.6° (111), 33.1° (200), and 47.5° (220) indicating the presence of cerium oxide (CeO2) were not present.

[0088] Comparative Example 4: Commercial Pt / C Catalysts

[0089] We directly used a 50% Pt / C catalyst from Johnson Matthey (denoted as Pt / C).

[0090] Performance testing

[0091] Preparation of working electrode

[0092] First, the working electrode was prepared. Specifically, more than 5 mg of the catalyst powder prepared in each of Examples 1-6 and Comparative Examples 1-3, or the commercial Pt / C catalyst of Comparative Example 4, 0.625 mg of acetylene black (conductive agent), and 0.625 mg of Nafion solution (5 wt%, binder) were weighed, added to 500 μL of anhydrous ethanol, and ultrasonically dispersed for 30 minutes to form a homogeneous slurry. 10 μL of the slurry was then pipetted onto a 1×1 cm plate. 2 The surface of nickel foam (coating amount of 0.5 mg / cm²) -2 The working electrode was obtained by vacuum drying at 70°C for 12 hours.

[0093] HER activity test of catalyst

[0094] Subsequently, the prepared catalyst electrode was used as the working electrode, a platinum sheet as the counter electrode, and an Hg / HgO electrode as the reference electrode, with a 1.0 mol•L electrolyte. -1 KOH solution (pH=14) was used to perform HER performance tests on the following three-electrode system using a CHI660D electrochemical workstation:

[0095] 1. Measurement of overpotential η using linear sweep voltammetry (LSV). 10 and η 100 The scan rate is 2 mV•s -1 The voltage range is -1.0 to 0 V vs. Hg / HgO, and the voltage is converted to the standard hydrogen electrode (RHE) voltage (E). RHE = E Hg / HgO +0.098V - 0.059 × pH). Read from the LSV curve at a current density of 10 mA·cm⁻¹ -2 and 100 mA·cm -2 The corresponding overpotentials (respectively, overpotentials η) 10 and overpotential η 100 The smaller the η value, the higher the activity of the catalyst in the hydrogen evolution reaction (HER).

[0096] 2. Perform Tafel analysis based on the LSV curve to determine the Tafel slope (b), where a current density of 10-100 mA·cm is selected based on the LSV curve. -2 For the region, the following Tafel equation is used for fitting to obtain the Tafel slope (b):

[0097]

[0098] Where b is the Tafel slope, and the unit is mV·dec. -1 The smaller the Tafel slope, the faster the reaction kinetics.

[0099] The HER performance test results of the three-electrode system are shown in Table 3 below.

[0100]

[0101] As shown in Table 3, the HER activity of Examples 1-6 is excellent: overpotential η 10 The overpotential η is 48-65 mV. 100 The voltage ranges from 128 to 158 mV, and the Tafel slope is 56.7 to 65.3 mV•dec. -1 It is significantly superior to the comparative example (Cat-C1-C3), and can significantly reduce overpotential and accelerate reaction kinetics.

[0102] Example 3 (Cat-3) showed the best activity: overpotential η 10 =48 mV, overpotential η 100 =128 mV, Tafel slope = 56.7 mV•dec -1 Approaching commercial Pt / C (overpotential η) 10 =43 mV, overpotential η 100 =113 mV), indicating that it has excellent activity.

[0103] The HER activity parameters of Comparative Examples 1-3 show that the activity of these catalysts is significantly reduced.

[0104] Commercial Pt / C exhibits the highest activity, but its cost is significantly higher than that of the catalyst of this invention, and it also has limitations at high current densities (e.g., 500 mA·cm⁻¹). -2 Its stability is poor, as shown in subsequent data.

[0105] Stability test results

[0106] The following catalyst stability tests were conducted using a CHI660D electrochemical workstation. Specifically, the catalyst durability under long-term continuous operation was evaluated using the chronoamperometry method. This simulates the scenario of continuous hydrogen production by the catalyst under constant voltage in a real water electrolysis device.

[0107] Specifically, a constant voltage (-0.1 V vs. RHE (reversible hydrogen electrode)) was applied to the working electrodes prepared above from various examples, comparative examples, and commercial Pt / C, and the tests were conducted continuously for 500 hours, with the change in current density over time being recorded continuously. The retention rate of current density was measured using the following formula: Retention rate (%) = (Current density after 500 hours / Initial current density) × 100%.

[0108] The results of the stability test are shown in Table 4 below.

[0109]

[0110] As shown in Table 4, after 500 hours, the current density retention rate of Examples 1-6 is greater than 90%, indicating that the catalyst structure is stable and the active sites are not easily lost.

[0111] The retention rate of current density in Comparative Examples 1-3 was no more than 80%, indicating that the catalyst structure was unstable.

[0112] Furthermore, the current density retention rate of commercial Pt / C was 84%, which was significantly worse than that of Examples 1-6, indicating that the catalyst of the present invention has better stability.

[0113] Obviously, those skilled in the art can make various modifications and variations to this disclosure without departing from the spirit and scope of this disclosure. Therefore, if such modifications and variations fall within the scope of this invention, this disclosure is also intended to include such modifications and variations.

Claims

1. A method for preparing a catalyst for hydrogen production by water electrolysis, characterized in that, The preparation method includes the following steps in sequence: (1) Add nickel nitrate and ammonium molybdate to a mixed solvent of deionized water and ethylene glycol, and stir thoroughly to dissolve; then add cobalt chloride and sodium hypophosphite, and stir thoroughly to dissolve; subsequently add glucose and cerium nitrate, and stir thoroughly to dissolve to form a precursor solution, wherein the weight ratio of nickel nitrate, ammonium molybdate, cobalt chloride, sodium hypophosphite, glucose and cerium nitrate is 1:0.59-0.67: 0.48-0.60: 0.40-0.60: 1.54-2.34: 0.08-0.43, and the ratio of the total weight of nickel nitrate, ammonium molybdate, cobalt chloride, sodium hypophosphite, glucose and cerium nitrate to the weight of the mixed solvent is in the range of 0.2:1-0.3:1; (2) The precursor solution is transferred to a stainless steel reactor with a polytetrafluoroethylene liner and reacted at 180-240°C for 12-18 hours to generate hydrothermal products. (3) The hydrothermal product is placed in a tube furnace and kept at 600-800℃ for 3-5 hours under nitrogen atmosphere protection to obtain the calcined product; (4) Grind the calcined product to obtain the catalyst.

2. The method for preparing the catalyst for hydrogen production by water electrolysis according to claim 1, characterized in that, In the mixed solvent, the weight ratio of deionized water to ethylene glycol is 2:1 to 1:

2.

3. A catalyst for hydrogen production by water electrolysis prepared according to the preparation method of claim 1 or 2, characterized in that, The catalyst for hydrogen production by water electrolysis comprises a carbon sintered support and active components supported on the surface and interior of the carbon sintered support. The active components include nickel-molybdenum nitride (NiMoN), cobalt phosphide (CoP), and cerium oxide. The catalyst has a porous structure.

4. The catalyst for hydrogen production by water electrolysis according to claim 3, characterized in that, The carbon sintered body carrier is a sintered product of glucose.

5. The catalyst for hydrogen production by water electrolysis according to claim 3, characterized in that, The average pore size of the porous structure is in the range of 5-30 nm.

6. The catalyst for hydrogen production by water electrolysis according to claim 3, characterized in that, The nickel-molybdenum nitride (NiMoN), cobalt phosphide (CoP), and cerium oxide are uniformly dispersed on the surface and inside the carbon sintered body carrier.

7. The application of the catalyst according to any one of claims 3-6 for hydrogen production by water electrolysis.

8. The application according to claim 7, characterized in that, The catalyst is coated on the working electrode.

9. The application according to claim 8, characterized in that, The working electrode is nickel foam.

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