Electrocatalytic anode for producing hydrogen by electrolyzing water as well as preparation method and application of electrocatalytic anode

Abstract

The invention relates to an electrocatalytic anode material for hydrogen production by water electrolysis and a preparation method and application thereof, and belongs to the technical field of hydrogen production by water electrolysis. The electrocatalytic anode takes three-dimensional metal foam as a conductive substrate, and a nickel disulfide and chromium trisulfide composite nano array is grown on the surface of the three-dimensional metal foam in situ. The electrocatalytic anode shows excellent oxygen evolution reaction activity in alkaline seawater and keeps long-term stability under high current density, and is suitable for an efficient seawater electrolysis hydrogen production system.

Description

Technical Field

[0001] This invention belongs to the field of water electrolysis for hydrogen production technology, and particularly relates to an electrocatalytic anode material for water electrolysis for hydrogen production, its preparation method and application. Background Technology

[0002] Hydrogen is an energy carrier with high specific energy density and zero carbon emissions. High-purity, green hydrogen fuel can be produced through water electrolysis, which is significant for reducing dependence on fossil fuels and integrating the utilization of intermittent renewable energy sources such as wind and solar power. With increasingly scarce freshwater resources, direct seawater electrolysis for hydrogen production is a promising alternative, not only utilizing the Earth's abundant seawater resources but also avoiding the energy-intensive seawater desalination process.

[0003] In seawater electrolysis for hydrogen production, due to Cl... – Electrode corrosion can occur via the metal chloride-hydroxide pathway, leading to anodic performance degradation. Furthermore, the chloride evolution reaction (CER) has faster kinetics than the oxygen evolution reaction (OER), and CER competes with OER, further generating corrosive hypochlorite through the reaction of chlorine gas with hydroxide ions. Therefore, high concentrations of Cl in seawater... – (Approximately 0.5 mol / L) poses a serious threat to water electrolysis catalysts. In recent years, alkaline seawater electrolysis has gradually become the main method for seawater electrolysis because it does not require a continuous supply of alkaline solution, and under alkaline conditions, there is a thermodynamic potential difference of 480 mV between the CER and OER, which can effectively suppress the CER at the anode. However, at high current densities (… j Under alkaline seawater oxidation (ASO) conditions, the rapid oxidation of water leads to the formation of protons (H+). + The rapid accumulation of ions leads to a sharp drop in local pH, even acidification. This acidification not only inhibits the OER reaction but also causes catalyst dissolution and structural damage, accelerating the degradation of conventional catalysts. Furthermore, the decrease in pH disrupts the alkaline microenvironment required for stable OER, promoting CER and thus exacerbating catalyst corrosion and impairing long-term stability.

[0004] Noble metal-based catalysts are widely used due to their superior OER catalytic performance, but their scarcity and high cost limit their large-scale application. Therefore, developing more economical and resource-rich inexpensive catalysts, such as transition metal oxides, sulfides, hydroxides, and nitrides, has become a research focus. Among these materials, nickel-based catalysts exhibit excellent OER performance in seawater electrolysis; however, during seawater electrolysis, active chloride species generated on the anode surface severely corrode NiOOH sites, leading to catalyst deactivation. Recent studies have employed chloride-resistant coatings (such as transition metal sulfides, nitrides, and phosphides) to address the corrosive challenges in seawater electrolysis. These materials undergo dynamic surface reconstruction during the ASO process, forming a highly electronegative ionic layer that repels chloride ions. – This effectively prevents corrosion and extends electrode life. However, most of the anion-repulsion-based catalysts developed in recent years only work at low current densities (<500 mA / cm²). 2 It exhibits relatively short stability (<1000h) under high current density, far below the durability required for seawater electrolysis under industrial conditions. During the ASO process at high current density, the rapid and continuous oxidation of water generates large amounts of H₂. + This leads to a decrease in the surface negative potential, thereby weakening the attraction of the anion to Cl. – The repulsive effect of H+ limits the effectiveness of traditional anion repulsion strategies at industrial-grade current densities. Furthermore, H+... + The large accumulation of these substances leads to a sharp drop in local pH, accelerating the corrosion of the electrode materials.

[0005] Therefore, how to develop an electrocatalytic anode that can be used for seawater electrolysis to produce hydrogen and maintain long-term stable performance under high current density is a technical problem that urgently needs to be solved. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides an electrocatalytic anode for hydrogen production via water electrolysis, its preparation method, and its application. This electrocatalytic anode exhibits excellent oxygen evolution reaction activity in alkaline seawater and maintains long-term stable performance under high current density, making it suitable for efficient seawater electrolysis hydrogen production systems.

[0007] In one aspect, the present invention provides an electrocatalytic anode for producing hydrogen by electrolysis of water, wherein the electrocatalytic anode uses a three-dimensional metal foam as a conductive substrate, and a composite nanoarray of nickel disulfide and chromium trisulfide is grown in situ on the surface of the three-dimensional metal foam.

[0008] In some embodiments, in the nickel disulfide and chromium trisulfide composite nanoarray, the nickel disulfide is in the form of nanosheets, and the chromium trisulfide is in the form of nanoparticles embedded in the nickel disulfide nanosheets.

[0009] Another aspect of the present invention provides a method for preparing the above-mentioned electrocatalytic anode for hydrogen production by water electrolysis, comprising the following steps: Nickel salt, chromium salt and urea are dissolved in water to obtain a reaction solution; The three-dimensional metal foam is vertically immersed into the reaction solution and hydrothermal reaction is carried out in a closed environment to grow a nickel-chromium layered double hydroxide nanoarray on the surface of the three-dimensional metal foam in situ. Under inert gas protection, a three-dimensional metal foam on which the nickel-chromium layered double hydroxide nanoarray is grown is sintered together with a sulfur source to sulfide the nickel-chromium layered double hydroxide nanoarray to form a composite nanoarray of nickel disulfide and chromium trisulfide. After cooling to room temperature, an electrocatalytic anode for producing hydrogen by electrolysis of water is obtained.

[0010] In some embodiments, the total molar concentration of nickel and chromium salts in the reaction solution is 10-100 mmol / L, the molar ratio of nickel and chromium salts is 1:5-5:1, and the ratio of the total molar amount of nickel and chromium salts to the molar amount of urea is 1:1-1:10.

[0011] In some embodiments, the hydrothermal reaction temperature is 120~150°C and the reaction time is 6~8h.

[0012] In some embodiments, the nickel salt is selected from at least one of nickel nitrate, nickel chloride, nickel acetate, and nickel sulfate, and the chromium salt is selected from at least one of chromium nitrate, chromium chloride, chromium acetate, and chromium sulfate.

[0013] In some embodiments, the sintering step specifically involves heating to 300°C to 360°C at a heating rate of 1 to 5°C / min and holding for 0.7 to 2 hours to carry out the sulfidation reaction.

[0014] In some embodiments, the sintering and vulcanization process is carried out in a tubular furnace with an inert gas flow, and a three-dimensional metal foam with the nickel-chromium layered double hydroxide nanoarray grown on it is placed in the middle of the tubular furnace, with the sulfur source placed upstream of the inert gas flow direction in the tubular furnace.

[0015] In some embodiments, the sulfur source is in excess during sintering and vulcanization, and the sulfur source is selected from at least one of sulfur powder and thioacetamide.

[0016] In another aspect, the present invention provides the application of the above-mentioned electrocatalytic anode for hydrogen production by water electrolysis in the production of hydrogen by alkaline seawater electrolysis.

[0017] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows: 1. The electrocatalytic anode for hydrogen production via water electrolysis provided by this invention has a composite nanoarray of nickel disulfide and chromium trisulfide grown in situ on the surface of a three-dimensional metal foam substrate. During water electrolysis, nickel disulfide generates sulfate ions in situ during oxidation, thereby forming a durable electrostatic barrier network that can effectively repel Cl-. – It prevents chlorine corrosion attack, and at the same time, chromium trisulfide can promote the OH- – The accumulation of proton H + The resulting acidification stabilizes the interfacial environment. Through a combination of anion repulsion and hydroxide ion enrichment, a stable alkaline negatively charged microenvironment is maintained on the electrocatalytic anode surface. This microenvironment sustains the oxygen evolution reaction activity of the electrocatalytic anode at ampere-level current densities, exhibiting excellent durability. Specifically, in three-electrode alkaline seawater oxidation tests, it can achieve an oxygen evolution reaction activity at 1 A / cm². 2 Running for over 1600 hours at 2A / cm 2 It has demonstrated excellent stability after operating for over 800 hours; in an anion exchange membrane water electrolyzer, at 1 A / cm 2 It exhibits durability exceeding 600 hours; 2. The method for preparing the electrocatalytic anode for hydrogen production by water electrolysis provided by the present invention has a simple process flow, requires no complicated post-processing, uses readily available and inexpensive raw materials, can be purchased on a large scale, and is suitable for industrial production and application. 3. When the electrocatalytic anode for hydrogen production by water electrolysis provided by this invention is used as an anode in alkaline seawater electrolysis for hydrogen production, it can adjust the local pH near the anode and inhibit corrosion caused by active chlorine, thereby maintaining long-term stable performance under high current density. Attached Figure Description

[0018] Figure 1 The image shows the XRD pattern of the electrocatalytic anode material prepared in Example 1 of this invention. Figure 2 This is a SEM image of the composite nanoarray of nickel disulfide and chromium trisulfide on the surface of the nickel foam in the electrocatalytic anode material prepared in Example 1 of this invention; Figure 3 This is a SEM image of the nickel-chromium layered double hydroxide nanoarray on the surface of the nickel foam in the electrocatalytic anode material prepared in Comparative Example 1 of this invention. Figure 4 This is a SEM image of the nickel disulfide nanoarray on the surface of the nickel foam in the electrocatalytic anode material prepared in Comparative Example 2 of this invention. Figure 5 The images shown are transmission electron microscope (TEM) images of the nickel disulfide and chromium trisulfide composite nanoarrays on the surface of the nickel foam in the electrocatalytic anode material prepared in Example 1 of this invention. (a) is a TEM image, and (b) is an HRTEM image. Figure 6 This is an EDS surface scan of the composite nanoarray of nickel disulfide and chromium trisulfide on the surface of the nickel foam in the electrocatalytic anode material prepared in Example 1 of this invention; Figure 7 The image shows a HAADF-STEM image of a composite nanoarray of nickel disulfide and chromium trisulfide on the surface of nickel foam in the electrocatalytic anode material prepared in Example 1 of this invention. Figure 8 This is a comparison of linear sweep voltammetric curves of the electrocatalytic anodes prepared in Example 1 and Comparative Examples 1-3 of the present invention and the anodic oxygen evolution reaction of nickel foam in alkaline seawater. Figure 9 This is a comparison chart of Tafel curves of the electrocatalytic anodes prepared in Example 1 and Comparative Examples 1-3 of the present invention and the anodic oxygen evolution reaction of nickel foam in alkaline seawater. Figure 10 The following are electrochemical performance graphs of the electrocatalytic anode prepared in Example 1 of this invention during the anodic oxygen evolution reaction in alkaline seawater, alkaline simulated seawater, and alkaline freshwater. (a) is a linear sweep voltammetry curve, and (b) is the voltammetry curve at 100 mA / cm². 2 500mA / cm 2 and 1000mA / cm 2 The overpotential diagram corresponding to the current density; Figure 11 The image shows a comparison of linear sweep voltammetric curves of the electrocatalytic anodes prepared in Examples 1-3 of this invention during the anodic oxygen evolution reaction in alkaline seawater. Figure 12 The linear sweep voltammetry curves of the electrocatalytic anodes prepared in Examples 1, 4 and 5 of this invention during the anodic oxygen evolution reaction in alkaline seawater are compared. Figure 13 This is a comparison of linear sweep voltammetric curves of the electrocatalytic anodes prepared in Examples 1 and 6 of this invention during the anodic oxygen evolution reaction in alkaline seawater. Figure 14 This is a comparison of linear sweep voltammetric curves of the electrocatalytic anodes prepared in Examples 1, 7 and 8 of this invention during the anodic oxygen evolution reaction in alkaline seawater. Figure 15 This is a comparison of linear sweep voltammetric curves of the electrocatalytic anodes prepared in Examples 1 and 9 of this invention during the anodic oxygen evolution reaction in alkaline seawater. Figure 16 This is a comparison of linear sweep voltammetric curves of the electrocatalytic anodes prepared in Examples 1 and 10 of the present invention during the anodic oxygen evolution reaction in alkaline seawater. Figure 17The electrocatalytic anodes prepared in Example 1 and Comparative Examples 1-2 of this invention were used in alkaline seawater at 1 A / cm 2 Stability curves at current density; Figure 18 The electrocatalytic anode prepared in Example 1 of this invention was tested in alkaline seawater at 2 A / cm. 2 Stability curves at current density; Figure 19 Linear scanning voltammetry curves and energy consumption variation graphs of the electrocatalytic anodes prepared in Example 1 and Comparative Example 3 of this invention applied in an anion exchange membrane water electrolyzer in alkaline seawater; Figure 20 This is a stability curve of the electrocatalytic anodes prepared in Example 1 and Comparative Example 3 of the present invention in an anion exchange membrane water electrolyzer in alkaline seawater. Detailed Implementation

[0019] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] This invention provides an electrocatalytic anode for hydrogen production by water electrolysis. The electrocatalytic anode uses a three-dimensional metal foam as a conductive substrate, and a composite nanoarray of nickel disulfide and chromium trisulfide is grown in situ on the surface of the three-dimensional metal foam.

[0021] The aforementioned electrocatalytic anode for hydrogen production via water electrolysis features an in-situ grown nickel disulfide and chromium trisulfide composite nanoarray on its three-dimensional metal foam substrate. During water electrolysis, nickel disulfide ions are oxidized in situ to generate sulfate ions, thus forming a durable electrostatic barrier network that effectively repels Cl-. – It prevents chlorine corrosion attack, and at the same time, chromium trisulfide can promote the OH- – The accumulation of proton H + The resulting acidification stabilizes the interfacial environment. Through a combination of anion repulsion and hydroxide ion enrichment, a stable alkaline negatively charged microenvironment is maintained on the electrocatalytic anode surface. This microenvironment sustains the oxygen evolution reaction activity of the electrocatalytic anode at ampere-level current densities, exhibiting excellent durability. Specifically, in three-electrode alkaline seawater oxidation tests, it can achieve an oxygen evolution reaction activity at 1 A / cm². 2 Running for over 1600 hours at 2A / cm 2 It has demonstrated excellent stability after operating for over 800 hours; in an anion exchange membrane water electrolyzer, at 1 A / cm 2 It exhibits durability exceeding 600 hours.

[0022] In a preferred embodiment, in the nickel disulfide and chromium trisulfide composite nanoarray, nickel disulfide is in the form of nanosheets and chromium trisulfide is in the form of nanoparticles embedded in the nickel disulfide nanosheets. This unique structure can provide an efficient channel for charge transfer, thereby exhibiting excellent oxygen evolution reaction activity.

[0023] In a preferred embodiment, the three-dimensional metal foam is selected from any one of nickel foam, cobalt foam, iron foam, copper foam, and titanium foam. This preferred embodiment specifically lists types of three-dimensional metal foams that are inexpensive, have good electrical conductivity, and are conducive to the growth of nanoarrays.

[0024] This invention also provides a method for preparing an electrocatalytic anode for hydrogen production by water electrolysis, comprising the following steps: S1. Dissolve nickel salt, chromium salt and urea in water to obtain a reaction solution; wherein, both nickel salt and chromium salt are soluble inorganic salts; S2. The three-dimensional metal foam is vertically immersed into the reaction solution and hydrothermal reaction is carried out in a closed environment to grow a nickel-chromium layered double hydroxide nanoarray on the surface of the three-dimensional metal foam in situ. S3. Under inert gas protection, a three-dimensional metal foam with a nickel-chromium layered double hydroxide nanoarray grown on it is sintered together with a sulfur source to sulfide the nickel-chromium layered double hydroxide nanoarray to form a nickel disulfide and chromium trisulfide composite nanoarray. After cooling to room temperature, an electrocatalytic anode for producing hydrogen by electrolysis of water is obtained.

[0025] The above-mentioned method for preparing the electrocatalytic anode for hydrogen production by water electrolysis has a simple process flow, requires no complicated post-processing, uses readily available and inexpensive raw materials, can be purchased on a large scale, and is suitable for industrial production and application.

[0026] In a preferred embodiment, the total molar concentration of nickel and chromium salts in the reaction solution is 10-100 mmol / L, the molar ratio of nickel to chromium salts is 1:5-5:1, and the ratio of the total molar amount of nickel and chromium salts to the molar amount of urea is 1:1-1:10. This preferred embodiment specifically defines the amount and ratio of each reactant in the hydrothermal reaction solution. Under this preferred amount and ratio, the anion repulsion and hydroxide ion enrichment of the electrocatalytic anode for hydrogen production by water electrolysis are balanced, thereby exhibiting better durability at ampere-level current densities.

[0027] In a preferred embodiment, the hydrothermal reaction temperature is 120~150℃, and the reaction time is 6~8h. This preferred embodiment specifically defines the preferred hydrothermal reaction temperature and time, which is more conducive to controlling the morphology of the nickel-chromium layered double hydroxide nanoarray and obtaining better oxygen evolution reaction activity.

[0028] In a preferred embodiment, the nickel salt is selected from at least one of nickel nitrate, nickel chloride, nickel acetate, and nickel sulfate, and the chromium salt is selected from at least one of chromium nitrate, chromium chloride, chromium acetate, and chromium sulfate. This preferred embodiment lists preferred types of nickel and chromium salts that are inexpensive and have good solubility.

[0029] In a preferred embodiment, the sintering and vulcanization process is carried out in a tubular furnace purged with inert gas. A three-dimensional metal foam with a nickel-chromium layered double hydroxide nanoarray is placed in the center of the tubular furnace, and a sulfur source is placed upstream of the inert gas flow. In this preferred embodiment, placing the three-dimensional metal foam with the nickel-chromium layered double hydroxide nanoarray in the center of the tubular furnace ensures the appropriate temperature for the vulcanization reaction, guaranteeing sufficient vulcanization. Placing the sulfur source upstream of the inert gas flow allows it to be fully vaporized and carried by the gas flow to the center of the tubular furnace to participate in the vulcanization reaction. It should be noted that the three-dimensional metal foam with the nickel-chromium layered double hydroxide nanoarray and the sulfur source are placed in two separate quartz boats, which are then placed in the tubular furnace.

[0030] In a preferred embodiment, the sintering step specifically involves heating to 300°C~360°C at a heating rate of 1~5°C / min and holding for 0.7~2 hours. This preferred embodiment specifically defines the preferred process parameters for the sintering step. Under these preferred process parameters, it can be ensured that the nickel-chromium layered double hydroxide nanoarray is fully sulfided to form a nickel disulfide and chromium trisulfide composite nanoarray.

[0031] In a preferred embodiment, an excess of sulfur source is used during the sintering and vulcanization process. The sulfur source is selected from at least one of sulfur powder and thioacetamide. This preferred embodiment specifically lists preferred types of sulfur sources that are inexpensive and easily vaporized to participate in the vulcanization reaction.

[0032] In a preferred embodiment, the inert gas is selected from at least one of nitrogen, argon, and helium. This preferred embodiment specifically lists preferred types of inert gases.

[0033] This invention further provides the application of an electrocatalytic anode for hydrogen production through water electrolysis in alkaline seawater electrolysis. When this electrocatalytic anode is used as an anode in alkaline seawater electrolysis, it can regulate the local pH near the anode and inhibit corrosion caused by active chlorine, thereby maintaining long-term stable performance under high current densities.

[0034] To more clearly and in detail introduce the electrocatalytic anode material for hydrogen production by water electrolysis provided in the embodiments of the present invention, as well as its preparation method and application, the following description will be based on specific embodiments.

[0035] Example 1 A method for preparing an electrocatalytic anode for hydrogen production by water electrolysis includes the following steps: (1) Weigh out nickel nitrate, chromium nitrate and urea, and dissolve them evenly in deionized water to obtain a reaction solution; wherein the concentration of nickel nitrate is 22.5 mmol / L, the concentration of chromium nitrate is 15 mmol / L and the concentration of urea is 100 mmol / L. (2) The nickel foam (abbreviated as NF) was vertically immersed into the reaction solution prepared in step (1), and the reaction solution and the immersed nickel foam were transferred together to a sealed container and subjected to hydrothermal reaction at 120°C for 6 hours. After the reaction was completed, a nickel-chromium layered double hydroxide nanoarray (abbreviated as NiCr LDH) was grown in situ on the surface of the nickel foam. (3) Place the nickel foam (NiCrLDH / NF) with nickel-chromium layered double hydroxide nanoarrays obtained in step (2) in a quartz boat and place it in the middle of a tube furnace; weigh 0.5g of sulfur powder and place it in another quartz boat and place it at one end of the tube furnace connected to the gas inlet pipe; continuously introduce argon gas into the tube furnace through the gas inlet pipe, and the gas flows out through the gas outlet pipe connected to the other end of the tube furnace; under the argon atmosphere, heat the tube furnace to 330℃ at a heating rate of 3℃ / min and keep it for 1h for sintering and sulfidation, so that the NiCr LDH nanoarray is sulfided into a composite nanoarray of nickel disulfide and chromium trisulfide (NiS2 / Cr2S3), and naturally cool it to room temperature under the flow of argon gas to obtain nickel foam (NiS2 / Cr2S3 / NF) with nickel disulfide and chromium trisulfide composite nanoarrays grown in situ on the surface, which is used as an electrocatalytic anode for electrolysis of water to produce hydrogen.

[0036] Example 2 The difference between this embodiment and Example 1 is that the concentration of nickel nitrate in the reaction solution is 83.33 mmol / L and the concentration of chromium nitrate is 16.67 mmol / L.

[0037] Example 3 The difference between this embodiment and Example 1 is that the concentration of nickel nitrate in the reaction solution is 1.67 mmol / L and the concentration of chromium nitrate is 8.33 mmol / L.

[0038] Example 4 The difference between this embodiment and Example 1 is that nickel chloride is used instead of nickel nitrate, and the concentration of nickel chloride in the reaction solution is 22.5 mmol / L.

[0039] Example 5 The difference between this embodiment and Example 1 is that chromium chloride is used instead of chromium nitrate, and the concentration of chromium chloride in the reaction solution is 15 mmol / L.

[0040] Example 6 The difference between this embodiment and Embodiment 1 is that the hydrothermal reaction temperature is 150℃ and the reaction time is 8h.

[0041] Example 7 The difference between this embodiment and Embodiment 1 is that in the sintering step, the temperature is increased to 300°C at a heating rate of 1°C / min and held for 2 hours to carry out the sulfidation reaction.

[0042] Example 8 The difference between this embodiment and Embodiment 1 is that in the sintering step, the temperature is increased to 360°C at a heating rate of 5°C / min and held for 0.7h to carry out the sulfidation reaction.

[0043] Example 9 The difference between this embodiment and Embodiment 1 is that the amount of sulfur powder added in the sintering step is 0.1g.

[0044] Example 10 The difference between this embodiment and Embodiment 1 is that cobalt foam is used instead of nickel foam.

[0045] Comparative Example 1 The difference between this comparative example and Example 1 is that step (3) was not performed, and the nickel foam (abbreviated as NiCr LDH / NF) with nickel-chromium layered double hydroxide nanoarrays obtained in step (2) was directly used as the electrocatalytic anode.

[0046] Comparative Example 2 The difference between this comparative example and Example 1 is that: no chromium nitrate was added to the reaction solution, and the concentration of nickel nitrate was 37.5 mmol / L; after hydrothermal reaction, nickel hydroxide nanoarrays were grown in situ on the surface of the nickel foam; after sintering and sulfiding with sulfur powder, nickel foam with nickel disulfide nanoarrays grown in situ on the surface (abbreviated as NiS2 / NF) was prepared and used as an electrocatalytic anode.

[0047] Comparative Example 3 5 mg RuO2 (20%) was mixed with 30 μL of 5% Nafion solution, 485 μL of anhydrous ethanol, and 485 μL of deionized water. The mixture was ultrasonically treated for 30 min to obtain a uniform catalyst ink. 100 μL of the catalyst ink was then uniformly coated onto a 1×1 cm² substrate. 2 The surface of the nickel foam is sized and allowed to dry naturally to obtain nickel foam coated with ruthenium dioxide (abbreviated as RuO2 / NF), which is used as an electrocatalytic anode.

[0048] Characterization test 1. Phase composition analysis X-ray diffraction analysis was performed on the electrocatalytic anode material prepared in Example 1, and the results are as follows: Figure 1 As shown. By Figure 1It can be seen that the characteristic diffraction peaks in the range of 20°-80° can be attributed to the NiS2 (PDF#80-0375) crystal phase, the Cr2S3 (PDF#72-1224) crystal phase, and metallic Ni. This confirms that the electrocatalytic anode material prepared in Example 1 has a composite catalyst of nickel disulfide and chromium trisulfide growing on the surface of the nickel foam.

[0049] 2. Morphological characteristics SEM images of the nickel foam surface catalyst in the electrocatalytic anode materials prepared in Examples 1 and 1-2 are shown below. Figures 2-4 As shown. Comparison Figures 2-4 As can be seen, the nickel disulfide and chromium trisulfide composite catalyst on the surface of the nickel foam in Example 1 and the nickel-chromium layered double hydroxide catalyst obtained without sintering and sulfidation in Comparative Example 1 both exhibit regular nanosheet structures. However, the nickel disulfide catalyst on the surface of the nickel foam in Comparative Example 2 exhibits a short nanowire morphology, which is completely different from the morphology of Example 1 and Comparative Example 1. This indicates that in Example 1 of the present invention, there is an interaction between nickel salt and chromium salt during the hydrothermal reaction process to grow a nickel-chromium layered double hydroxide nanoarray on the surface of the nickel foam. The nickel-chromium layered double hydroxide nanoarray retains its nanosheet structure after sulfidation.

[0050] The structure of the nickel disulfide and chromium trisulfide composite nanoarray on the surface of the nickel foam in the electrocatalytic anode material prepared in Example 1 was further analyzed using transmission electron microscopy. The results are as follows: Figures 5-7 As shown. Figure 5 In the figure, (a) shows a TEM image of the composite nanoarray of nickel disulfide and chromium trisulfide. It can be seen that NiS2 has a nanosheet structure and a rough surface, while Cr2S3 is embedded in the NiS2 nanosheet in the form of nanoparticles; (b) shows an HRTEM image that reveals clear lattice fringes. The measured interplanar spacings of 2.8 Å and 2.6 Å correspond to the (200) crystal plane of NiS2 and the (11-3) crystal plane of Cr2S3, respectively, indicating that a heterogeneous interface is formed between the two phases. Figure 6 The EDS surface scan shown confirms that Cr, Ni, and S elements are uniformly distributed within the nanosheets, further illustrating that Cr2S3 is embedded in NiS2 nanosheets in the form of nanoparticles. This unique bimetallic sulfide provides an efficient channel through phase charge transfer. Figure 7 The HAADF-STEM image shown further confirms the rough surface structure of NiS2 nanosheets, which can effectively promote electrolyte penetration and mass transfer processes.

[0051] 3. OER performance test In an alkaline seawater solution (specifically, a mixture of 1 mol / L KOH and seawater), a three-electrode system was used to evaluate the performance of the electrocatalytic anodes prepared in Example 1 and Comparative Examples 1-3, as well as the nickel foam, in the anodic oxygen evolution reaction (OER) in alkaline seawater. The results are as follows: Figure 8 and Figure 9 As shown. During the test, the electrocatalytic anodes prepared in Example 1 and Comparative Examples 1-3, as well as nickel foam, were used as working electrodes, the Hg / HgO electrode was used as the reference electrode, and the graphite rod was used as the counter electrode.

[0052] Figure 8 The following is a comparison of linear sweep voltammetry curves of the electrocatalytic anodes prepared in Example 1 and Comparative Examples 1-3, and of nickel foam undergoing the anodic oxygen evolution reaction in alkaline seawater. Figure 8 As can be seen, the NiS2 / Cr2S3 / NF prepared in Example 1 exhibits excellent OER performance during alkaline seawater oxidation, achieving 1 A / cm at an overpotential (η) of 341 mV. 2 The current density is significantly better than that of NiCr LDH / NF (573mV) prepared in Comparative Example 1, NiS2 / NF (585mV) prepared in Comparative Example 2, and RuO2 / NF (510mV) prepared in Comparative Example 3. This indicates that the electrocatalytic anode for hydrogen production by water electrolysis provided in the embodiments of the present invention has great application prospects in alkaline seawater electrolysis hydrogen production.

[0053] Figure 9 The diagram shows a comparison of Tafel curves for the anodic oxygen evolution reaction (OER) of the electrocatalytic anodes prepared in Example 1 and Comparative Examples 1-3, as well as that of nickel foam, in alkaline seawater. Figure 9 As can be seen, the Tafel slope of NiS2 / Cr2S3 / NF prepared in Example 1 is 29.6 mV / dec, which is significantly better than that of NiCr LDH / NF (114.0 mV / dec) prepared in Comparative Example 1, NiS2 / NF (99.3 mV / dec) prepared in Comparative Example 2, RuO2 / NF (82.2 mV / dec) and NF (239.6 mV / dec) prepared in Comparative Example 3. The NiS2 / Cr2S3 / NF prepared in Example 1 has a lower Tafel slope, highlighting its ability to improve charge transfer efficiency and demonstrating its superior electrochemical kinetic performance. This further verifies the potential of the electrocatalytic anode for hydrogen production by water electrolysis provided in this invention in alkaline seawater electrolysis.

[0054] Furthermore, the performance of the electrocatalytic anode prepared in Example 1 in anodic oxygen evolution reaction (OER) was evaluated using a three-electrode system in alkaline freshwater (specifically, 1 mol / L KOH) and simulated alkaline seawater (specifically, a mixture of 1 mol / L KOH and 0.5 mol / L NaCl). The results are as follows: Figure 10 As shown. By Figure 10 As can be seen, the NiS2 / Cr2S3 / NF prepared in Example 1 also exhibits excellent OER performance in alkaline freshwater and simulated alkaline seawater. Its η (instance potential) at different current densities in alkaline seawater, alkaline simulated seawater, and alkaline freshwater is not significantly different. Specifically, at 100 mA / cm², the η value is relatively consistent. 2 At the given current density, η in alkaline seawater, alkaline simulated seawater, and alkaline freshwater are 239 mV, 237 mV, and 273 mV, respectively; at 500 mA / cm², the values ​​are... 2 At the given current density, η in alkaline seawater, alkaline simulated seawater, and alkaline freshwater are 304 mV, 313 mV, and 342 mV, respectively; at 1000 mA / cm², the values ​​are... 2 At the specified current density, the η values ​​in alkaline seawater, alkaline simulated seawater, and alkaline freshwater were 341 mV, 359 mV, and 374 mV, respectively. Among them, the NiS2 / Cr2S3 / NF prepared in Example 1 showed the best performance in alkaline seawater. This is because seawater has a complex composition and contains various ions, which may promote activity during the OER process.

[0055] Furthermore, in an alkaline seawater solution (specifically, a mixture of 1 mol / L KOH and seawater), a three-electrode system was used to evaluate the performance of the electrocatalytic anodes prepared in Examples 2-10 and the nickel foam in alkaline seawater for the oxygen evolution reaction (OER). The results compared with those of Example 1 are as follows: Figures 11-16 As shown, it is at 500mA / cm 2 and 1000mA / cm 2 The values ​​of η at the current density are shown in Table 1.

[0056] Table 1. η of the electrocatalytic anodes prepared in Examples 1-10 at different current densities in alkaline seawater.

[0057] From Table 1 and Figures 11-16 As can be seen, the electrocatalytic anodes prepared in Examples 1-10 of this invention all exhibit excellent OER performance in alkaline seawater.

[0058] 4. Stability Test At 25°C, the stability of the electrocatalytic anodes prepared in Example 1 and Comparative Examples 1-2 in alkaline seawater electrolysis was tested using a three-electrode system in an alkaline seawater aqueous solution (specifically, a mixture of 1 mol / L KOH and seawater). The results are as follows: Figure 17 (The electrocatalytic anodes prepared in Examples 1 and 1-2 are at 1 A / cm) 2 (Stability curves at current density) and Figure 18 (The electrocatalytic anode prepared in Example 1 is at 2A / cm) 2 The stability curve at current density is shown in the figure. Figure 17 and Figure 18 As can be seen, the electrocatalytic anode prepared in Example 1 of this invention exhibits breakthrough long-term stability in alkaline seawater electrolysis, with a stability at 1 A / cm 2 No significant activity decay was observed after 1600 hours of continuous electrolysis at industrial-grade current density, even at 2A / cm². 2 It can maintain stable operation for 800 hours under ultra-high current density, and its durability index is significantly better than that of NiCrLDH / NF prepared in Comparative Example 1 (which shows performance degradation in less than 50 hours) and NiS2 / NF prepared in Comparative Example 2 (which shows performance degradation in less than 200 hours).

[0059] To comprehensively evaluate the application effect of electrocatalytic anodes in practical electrolyzers, an electrolyzer with an integrated anion exchange membrane (AEM) membrane electrode assembly (MEA) was designed and constructed. The electrocatalytic anodes prepared in Example 1 and Comparative Example 3 were used as anode materials, Pt / C / NF as cathodes, and alkaline seawater (specifically, a mixture of 1 mol / L KOH and seawater) as the electrolyte. – Transmission via AEM yields the following results: Figure 19 and Figure 20 As shown.

[0060] Figure 19 Linear scan voltammetry curves and energy consumption variation graphs of the electrocatalytic anodes prepared in Example 1 and Comparative Example 3 of this invention are shown in an anion exchange membrane water electrolyzer in alkaline seawater. Figure 19 As can be seen, the NiS2 / Cr2S3 / NF||Pt / C / NF provided in Embodiment 1 of the present invention has a performance of 1 A / cm 2 At the required current density, only 2.31V is needed, while Comparative Example 3 requires 2.96V to achieve 0.5A / cm². 2 The NiS2 / Cr2S3 / NF||Pt / C / NF provided in Example 1 exhibits superior catalytic performance due to its high current density. Furthermore, the NiS2 / Cr2S3 / NF||Pt / C / NF provided in Example 1 of this invention achieves a current density of 0.1 A / cm². 2The energy consumption is 3.74 kWh / Nm³. 3 H2, at 1A / cm 2 The energy consumption is 5.43 kWh / Nm³. 3 H2 has low energy consumption.

[0061] Figure 20 The stability curves of the electrocatalytic anodes prepared in Example 1 and Comparative Example 3 of this invention are shown in the application of anion exchange membrane water electrolyzers in alkaline seawater. It can be seen that the NiS2 / Cr2S3 / NF||Pt / C / NF provided in Example 1 of this invention exhibits a stability of 1 A / cm² in the anion exchange membrane water electrolyzer. 2 Its current density allows it to operate stably for over 600 hours, highlighting its excellent durability in high-performance electrolysis systems.

[0062] In summary, the electrocatalytic anode prepared in Example 1 of this invention has excellent performance in terms of low voltage, low energy consumption, and long-term stability, and it is promising for industrial application in seawater electrolysis for hydrogen production.

Claims

1. An electrocatalytic anode for hydrogen production by water electrolysis, characterized in that, The electrocatalytic anode uses a three-dimensional metal foam as a conductive substrate, and a composite nanoarray of nickel disulfide and chromium trisulfide is grown in situ on the surface of the three-dimensional metal foam.

2. The electrocatalytic anode for hydrogen production by water electrolysis according to claim 1, characterized in that, In the nickel disulfide and chromium trisulfide composite nanoarray, the nickel disulfide is in the form of nanosheets, and the chromium trisulfide is in the form of nanoparticles embedded in the nickel disulfide nanosheets.

3. The method for preparing the electrocatalytic anode for hydrogen production by water electrolysis as described in claim 1 or 2, characterized in that, Includes the following steps: Nickel salt, chromium salt and urea are dissolved in water to obtain a reaction solution; The three-dimensional metal foam is vertically immersed into the reaction solution and hydrothermal reaction is carried out in a closed environment to grow a nickel-chromium layered double hydroxide nanoarray on the surface of the three-dimensional metal foam in situ. Under inert gas protection, a three-dimensional metal foam on which the nickel-chromium layered double hydroxide nanoarray is grown is sintered together with a sulfur source to sulfide the nickel-chromium layered double hydroxide nanoarray to form a composite nanoarray of nickel disulfide and chromium trisulfide. After cooling to room temperature, an electrocatalytic anode for producing hydrogen by electrolysis of water is obtained.

4. The method for preparing the electrocatalytic anode for hydrogen production by water electrolysis according to claim 3, characterized in that, The total molar concentration of nickel and chromium salts in the reaction solution is 10-100 mmol / L, the molar ratio of nickel salt to chromium salt is 1:5-5:1, and the ratio of the total molar amount of nickel and chromium salts to the molar amount of urea is 1:1-1:

10.

5. The method for preparing the electrocatalytic anode for hydrogen production by water electrolysis according to claim 3 or 4, characterized in that, The hydrothermal reaction temperature is 120~150℃, and the reaction time is 6~8h.

6. The method for preparing the electrocatalytic anode for hydrogen production by water electrolysis according to claim 3 or 4, characterized in that, The nickel salt is selected from at least one of nickel nitrate, nickel chloride, nickel acetate, and nickel sulfate, and the chromium salt is selected from at least one of chromium nitrate, chromium chloride, chromium acetate, and chromium sulfate.

7. The method for preparing the electrocatalytic anode for hydrogen production by water electrolysis according to claim 3, characterized in that, The sintering step specifically involves heating to 300℃~360℃ at a heating rate of 1~5℃ / min and holding for 0.7~2h to carry out the sulfidation reaction.

8. The method for preparing the electrocatalytic anode for hydrogen production by water electrolysis according to claim 3 or 7, characterized in that, The sintering and vulcanization process is carried out in a tubular furnace with an inert gas flow. The three-dimensional metal foam with the nickel-chromium layered double hydroxide nanoarray grown on it is placed in the middle of the tubular furnace, and the sulfur source is placed upstream of the inert gas flow direction in the tubular furnace.

9. The method for preparing the electrocatalytic anode for hydrogen production by water electrolysis according to claim 3 or 7, characterized in that, The sulfur source is in excess during the sintering and vulcanization process, and the sulfur source is selected from at least one of sulfur powder and thioacetamide.

10. The application of the electrocatalytic anode for hydrogen production by water electrolysis as described in claim 1 or 2 in hydrogen production by alkaline seawater electrolysis.

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