Anode material for hydrogen production by electrolysis of water and preparation method and application thereof

Abstract

This invention discloses an anode material for hydrogen production via water electrolysis, its preparation method, and its application, belonging to the field of water electrolysis hydrogen production technology. The preparation method includes the following steps: using a three-electrode system, with NiFe layered double hydroxide as the working electrode, Pt as the counter electrode, Hg / HgO as the reference electrode, and ammonium molybdate solution as the electrolyte, applying a constant negative potential to the working electrode, and performing electrochemical Mo doping to obtain the anode material for water electrolysis hydrogen production. The catalytic activity of the anode material for water electrolysis hydrogen production of this invention is significantly improved, while the Tafel slope is reduced, making it suitable for industrial-grade high current density water electrolysis.

Description

Technical Field

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

[0002] Electrolysis of water to produce hydrogen is the core pathway for green hydrogen production. The oxygen evolution reaction (OER) at the anolyte, due to its slow four-electron transfer kinetics, has become a bottleneck limiting the overall water electrolysis efficiency. Current optimization of anode materials mainly focuses on two types of systems: 1. Noble metal-based materials: Primarily IrO2-based catalysts, these are the main anode materials in proton exchange membrane electrolyzers. Their intrinsic activity and stability can be improved through methods such as crystal facet engineering, but they are mainly suitable for strongly acidic environments. Alternatively, the amount of Ir used can be reduced and the quality activity improved through the support effect of bimetallic oxides such as CeO2-IrO2, but due to the scarcity of Ir reserves, the cost of these catalysts remains high.

[0003] 2. Non-precious metal-based materials: Primarily NiFe layered double hydroxides, these offer advantages such as low cost and good stability. Their performance can be controlled through extensive elemental doping, making them the mainstream anode material for alkaline electrolyzers. However, they suffer from drawbacks such as insufficient intrinsic activity and poor doping uniformity. Compared to Ir-based precious metal catalysts, NiFe-based materials require higher overpotentials to drive the OER reaction, necessitating doping to improve activity. Co-precipitation and other methods can introduce dopants, but these traditional methods tend to lead to dopant aggregation, reducing the utilization rate of catalytic active sites.

[0004] Therefore, existing OER catalysts rely on precious metals and are expensive: for example, Ir-based catalysts account for more than 40% of the cost of an electrolyzer. Although bimetallic catalysts can partially reduce the amount of precious metals used, they still cannot break the dependence on precious metals, which limits the large-scale deployment of water electrolysis equipment.

[0005] Furthermore, the doping process for non-precious metal catalysts is complex: existing doping processes struggle to balance doping effectiveness with low cost; wet chemical doping methods can easily lead to agglomeration of dopant elements and uneven distribution of active sites; while doping processes such as high-temperature calcination and plasma-assisted deposition require multiple steps and demand high-performance equipment, thus limiting the large-scale production of doped catalysts.

[0006] Meanwhile, the industrial-grade performance is insufficient: the existing NiFe layered double hydroxide catalysts have a sharp increase in overpotential and a large Tafel slope under high current density, which makes them prone to surface reconstruction and activity decay. They are difficult to meet the requirements of continuous operation of industrial electrolyzers under high current density and lead to increased energy consumption. Summary of the Invention

[0007] To address at least one of the aforementioned technical problems, the present invention aims to provide an anode material for hydrogen production via water electrolysis, its preparation method, and its application. The present invention, through a highly efficient and stable electrochemical Mo doping process, can solve the problems of complex doping processes, large Tafel slopes, and insufficient industrial-grade performance inherent in existing NiFe layered double hydroxide OER catalysts.

[0008] To achieve the above objectives, the first aspect of the present invention provides a method for preparing an anode material for hydrogen production via water electrolysis, comprising the following steps: A three-electrode system was adopted, with NiFe layered double hydroxide as the working electrode, Pt as the counter electrode, Hg / HgO as the reference electrode, and ammonium molybdate solution as the electrolyte. A constant negative potential was applied to the working electrode to perform electrochemical Mo doping, thereby obtaining the aforementioned anode material for hydrogen production by water electrolysis.

[0009] According to a specific embodiment of the present invention, preferably, the concentration of the ammonium molybdate solution is 0.008~0.012 mol / L. More preferably, the concentration of the ammonium molybdate solution is 0.01 mol / L.

[0010] According to a specific embodiment of the present invention, preferably, the constant negative potential is -1.2 to -0.8 V. More preferably, the constant negative potential is -1.0 V.

[0011] According to a specific embodiment of the present invention, preferably, the electrochemical Mo doping time is 1 to 5 minutes. More preferably, the electrochemical Mo doping time is 1 minute or 5 minutes. Even more preferably, the electrochemical Mo doping time is 1 minute.

[0012] A second aspect of the present invention provides an anode material for hydrogen production by water electrolysis, which is prepared by the above-described method for preparing an anode material for hydrogen production by water electrolysis.

[0013] The third aspect of the present invention provides the application of the above-mentioned anode material for hydrogen production by water electrolysis as an anode in hydrogen production by water electrolysis.

[0014] This invention has at least the following beneficial effects: This invention does not use precious metal catalysts, thus reducing material costs and circumventing the limitations of precious metal reserves. Furthermore, this invention prepares the anode material for hydrogen production through water electrolysis using a highly efficient and stable electrochemical constant voltage doping method, offering the advantage of simple process. The anode material prepared by this invention effectively incorporates Mo into a NiFe layered double hydroxide, exhibiting significant structural advantages. This anode material is suitable for highly efficient catalysis of the oxygen evolution reaction in alkaline media, demonstrating significantly improved catalytic activity and a reduced Tafel slope, making it suitable for industrial-grade high-current-density water electrolysis. Moreover, the stability of the anode material is enhanced. Attached Figure Description

[0015] Figure 1 The image shows the SEM-EDS surface scan results of the anode material for hydrogen production via water electrolysis in Example 1.

[0016] Figure 2 The XRD diffraction patterns are those of the NiFe layered double hydroxide electrode and the anode material for hydrogen production by water electrolysis in Example 1.

[0017] Figure 3 Raman spectra of anode materials for hydrogen production by water electrolysis at different electrochemical Mo doping times.

[0018] Figure 4 Comparison of OER performance of anode materials for water electrolysis hydrogen production with different electrochemical Mo doping times.

[0019] Figure 5 This is a comparison of the macroscopic morphology of the NiFe layered double hydroxide electrode and the anode material for hydrogen production by water electrolysis after OER electrochemical testing.

[0020] Figure 6 A comparison of electrode potentials of anode materials for hydrogen production by water electrolysis under different electrochemical Mo doping times at specific current densities.

[0021] Figure 7 Comparison of Tafel slopes for anode materials used in water electrolysis for hydrogen production at different electrochemical Mo doping times. Detailed Implementation

[0022] To provide a clearer understanding of the technical features, objectives, and beneficial effects of the present invention, the present invention will now be described in detail below, but this should not be construed as limiting the scope of the invention.

[0023] It should be noted that, unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0024] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0025] It should be understood that the terms “comprising,” “including,” and / or “containing” as used herein specify the presence of the stated features, integers, steps, components, or combinations thereof, but do not exclude the presence or addition of one or more other features, integers, steps, components, or combinations thereof.

[0026] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this invention.

[0027] According to a specific embodiment of the first aspect of the present invention, the present invention provides a method for preparing an anode material for hydrogen production by water electrolysis, comprising the following steps: A three-electrode system was adopted, with NiFe layered double hydroxide as the working electrode, Pt as the counter electrode, Hg / HgO as the reference electrode, and ammonium molybdate solution as the electrolyte. A constant negative potential was applied to the working electrode to perform electrochemical Mo doping, thereby obtaining the aforementioned anode material for hydrogen production by water electrolysis.

[0028] The NiFe layered double hydroxide, Pt, and Hg / HgO used in this invention can all be materials in the prior art, and this invention does not impose any special restrictions on them.

[0029] In some embodiments, the concentration of the ammonium molybdate solution is 0.008~0.012 mol / L. More preferably, the concentration of the ammonium molybdate solution is 0.01 mol / L. The ammonium molybdate solution can be prepared using conventional methods in the art, such as weighing a certain amount of ammonium molybdate and dissolving it in an appropriate amount of deionized water. During the dissolution process, methods such as magnetic stirring can be used to accelerate the dissolution until the solution becomes completely transparent and free of visible solid particles. By precisely controlling the amount of ammonium molybdate and the volume of deionized water, the concentration of the ammonium molybdate solution can be accurately controlled within the above-mentioned range, laying the foundation for subsequent controllable Mo doping.

[0030] This invention uses ammonium molybdate solution as the electrolyte. Ammonium molybdate is a common Mo source, and it can dissociate into MoO4 in aqueous solution. 2- The ions are then reduced and doped into the NiFe layered double hydroxide under electrochemical action.

[0031] In some embodiments, the constant negative potential is -1.2 to -0.8 V (relative to the Hg / HgO reference electrode). More preferably, the constant negative potential is -1.0 V (relative to the Hg / HgO reference electrode). It is understood that the negative potential here refers to the parameter value directly input to the electrochemical workstation.

[0032] In some embodiments, the electrochemical Mo doping time is 1 to 5 minutes. More preferably, the electrochemical Mo doping time is 1 minute or 5 minutes. Even more preferably, the electrochemical Mo doping time is 1 minute.

[0033] Under the working electrode potential controlled by the present invention, MoO4 2- Ions undergo a reduction reaction on the surface of the working electrode, generating low-valence Mo species that are doped into the lattice of NiFe layered double hydroxides or deposited on its surface. This invention, by precisely controlling the doping potential (most preferably -1.0 V), doping time (most preferably 1 min), and ammonium molybdate solution (most preferably 0.01 mol / L), can obtain a Mo-doped NiFe layered double hydroxide anode material with optimal performance, suitable for OER electrocatalysis in alkaline environments.

[0034] According to a specific embodiment of the second aspect of the present invention, the present invention provides an anode material for hydrogen production through water electrolysis, which is prepared by the above-described method for preparing an anode material for hydrogen production through water electrolysis. The anode material for hydrogen production through water electrolysis comprises Mo-doped NiFe layered double hydroxide.

[0035] According to a specific embodiment of the third aspect of the present invention, the present invention provides the application of the above-mentioned anode material for hydrogen production by water electrolysis as an anode in hydrogen production by water electrolysis.

[0036] This invention utilizes a one-step electrochemical doping process combining constant potential with a specific time window to prepare Mo-doped NiFe layered double hydroxides: without plasma pretreatment or other complex steps, Mo doping of NiFe layered double hydroxides is achieved directly under constant potential through an IT program, with a simple process flow and strong controllability.

[0037] Furthermore, this invention achieves time-dependent doping effects and electrocatalytic property regulation: shorter electrochemical Mo doping treatment can significantly improve the alkaline OER catalytic activity of NiFe layered double hydroxides and significantly reduce the overpotential, but excessively long electrochemical doping leads to a decrease in activity. For the optimized Mo-doped NiFe layered double hydroxide sample, at 100 mA / cm 2 With 400 mA / cm 2At the specified current density, the overpotential is significantly reduced, and the Tafel slope decreases by more than 50%. Furthermore, the material surface is smooth and free of deposits after OER testing, indicating that the material treated by this invention possesses the ability to efficiently electrolyze water at industrial-grade high current densities. In addition, constant-voltage Mo doping eliminates the oxidation peak in the 1.35 V to 1.5 V voltage range during OER testing, reducing deposits on the sample surface after OER testing, indicating improved sample stability after doping. Moreover, this invention employs a three-electrode system, facilitating the conversion of the reference electrode potential to the working electrode relative to the reversible hydrogen electrode (RHE), which is beneficial for process control; whereas with a two-electrode system, it is difficult to determine the actual potential applied to the working electrode.

[0038] Furthermore, the structure of the doped material was characterized using SEM-EDS, XRD, and Raman spectroscopy. The microstructure of the electrochemically Mo-doped sample was characterized, confirming the effective doping of Mo and explaining the source of the optimized electrochemical performance. SEM-EDS demonstrated the effective incorporation of Mo into the NiFe layered double hydroxide, XRD showed the formation of Mo-related phases, and Raman spectroscopy revealed the effect of different doping times on the surface reconstruction of the material, verifying the structural advantages of the material of this invention.

[0039] The technical solutions of the present invention are specifically illustrated below through embodiments, but the present invention is not limited to these embodiments. Of course, various modifications can be made within the scope of the key points of the present invention.

[0040] Example 1

[0041] A certain amount of ammonium molybdate was weighed and dissolved in an appropriate amount of deionized water to obtain an ammonium molybdate solution of approximately 0.01 mol / L. Electrochemical Mo doping was then performed in a three-electrode system. First, the doped NiFe layered double hydroxide electrode was cut to a suitable size (1 cm). 2 Using a Pt sheet as the working electrode, an Hg / HgO electrode as the reference electrode, and an ammonium molybdate solution as the electrolyte, a complete three-electrode electrolytic cell is formed. Then, constant potential electrochemical doping is performed using an electrochemical workstation. A constant negative potential of -1.0 V is applied to the working electrode for 1 min, resulting in the anode material for hydrogen production by water electrolysis.

[0042] Example 2

[0043] This embodiment is basically the same as Embodiment 1, except that the electrochemical Mo doping time is adjusted to 5 minutes, and the rest is the same as Embodiment 1.

[0044] Comparative Example 1

[0045] This comparative example is basically the same as Example 1, except that the electrochemical Mo doping time was adjusted to 3 min, 7.5 min and 10 min respectively, while the rest was the same as Example 1, resulting in 3 samples of anode materials for water electrolysis to produce hydrogen.

[0046] Comparative Example 2

[0047] This comparative example is basically the same as Example 1, except that the concentration of the ammonium molybdate solution is adjusted to 0.02 mol / L, and everything else is the same as in Example 1.

[0048] Comparative Example 3

[0049] This comparative example is basically the same as Example 1, except that the ammonium molybdate solution is replaced with sodium molybdate solution, while the concentration remains the same. Everything else is the same as in Example 1.

[0050] Figure 1 The image shows the SEM-EDS surface scan results of the anode material for hydrogen production via water electrolysis in Example 1. Figure 2 The XRD diffraction patterns are those of the NiFe layered double hydroxide electrode (i.e., the "original" electrode in the figure) and the anode material for hydrogen production by water electrolysis in Example 1. Figure 3 Raman spectra of anode materials for hydrogen production by water electrolysis at different electrochemical Mo doping times. Figure 4 Comparison of OER performance of anode materials for water electrolysis hydrogen production with different electrochemical Mo doping times. Figure 5 This is a comparison of the macroscopic morphology of the NiFe layered double hydroxide electrode and the anode material for hydrogen production by water electrolysis after OER electrochemical testing. Figure 6 A comparison of electrode potentials of anode materials for hydrogen production by water electrolysis under different electrochemical Mo doping times at specific current densities. Figure 7 Comparison of Tafel slopes for anode materials used in water electrolysis for hydrogen production at different electrochemical Mo doping times.

[0051] The OER performance test was conducted using a CHI760E electrochemical workstation in a standard three-electrode system at room temperature. The anode materials for hydrogen production via water electrolysis prepared in the above examples and comparative examples were used directly as the working electrode, Hg / HgO as the reference electrode, and a Pt sheet as the counter electrode. The test was performed in a 1 mol / L KOH solution. The sample used as the working electrode was cut into a 1 cm × 1 cm piece, and the working electrode area immersed in the KOH solution was 0.5 cm². 2 The voltage scan rate was 5 mV / s. When demonstrating OER performance using LSV polarization curves, the working electrode potentials were all converted to potentials relative to the reversible hydrogen electrode (RHE) and 85% iR compensation was used.

[0052] The results above show that, for the optimized Mo-doped NiFe layered double hydroxide sample prepared in Example 1, at 100 mA / cm², 2 With 400 mA / cm 2 At the specified current density, the overpotential was significantly reduced, and the Tafel slope decreased by more than 50%. Furthermore, the material surface was smooth and free of deposits after OER testing, indicating that the material treated according to this invention possesses the ability to efficiently electrolyze water at industrial-grade high current densities. In addition, constant-voltage Mo doping eliminated the oxidation peak in the 1.35V to 1.5V voltage range during OER testing and reduced deposits on the sample surface after OER testing, indicating improved sample stability after doping.

[0053] For alkaline OER, Example 1 was at 400 mA / cm 2 The overpotential was 319 mV in Example 2 at 400 mA / cm². 2 The overpotential at the specified value was 336 mV, while that at 400 mA / cm² was used in Comparative Example 1. 2 The overpotentials at the following values ​​were 340 mV (3 min), 344 mV (7.5 min), and 347 mV (10 min), respectively. Comparative Example 2 was at 400 mA / cm². 2 The overpotential at the specified value was 343 mV, while that at the specified value in Comparative Example 3 was 400 mA / cm. 2 The overpotential is 326 mV. It can be understood that the overpotential is the difference obtained by converting the working electrode potential to a potential relative to RHE and subtracting the standard electrode potential of the OER reaction, which is 1.23 V.

[0054] SEM-EDS confirmed the effective incorporation of Mo into the NiFe layered double hydroxide, XRD showed the formation of Mo-related phases, and Raman spectroscopy demonstrated the effect of different doping times on the surface reconstruction of the material, thus verifying the structural advantages of the material of this invention.

[0055] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing an anode material for hydrogen production via water electrolysis, comprising the following steps: A three-electrode system was adopted, with NiFe layered double hydroxide as the working electrode, Pt as the counter electrode, Hg / HgO as the reference electrode, and ammonium molybdate solution as the electrolyte. A constant negative potential was applied to the working electrode to perform electrochemical Mo doping, thereby obtaining the aforementioned anode material for hydrogen production by water electrolysis.

2. The method for preparing the anode material for hydrogen production by water electrolysis according to claim 1, wherein, The concentration of the ammonium molybdate solution is 0.008~0.012 mol / L.

3. The method for preparing the anode material for hydrogen production by water electrolysis according to claim 1 or 2, wherein, The concentration of the ammonium molybdate solution is 0.01 mol / L.

4. The method for preparing the anode material for hydrogen production by water electrolysis according to claim 1, wherein, The constant negative potential is -1.2 to -0.8 V.

5. The method for preparing the anode material for hydrogen production by water electrolysis according to claim 1 or 4, wherein, The constant negative potential is -1.0 V.

6. The method for preparing the anode material for hydrogen production by water electrolysis according to claim 1, wherein, The electrochemical Mo doping time is 1~5 min.

7. The method for preparing the anode material for hydrogen production by water electrolysis according to claim 1 or 6, wherein, The electrochemical Mo doping time is 1 min or 5 min.

8. The method for preparing the anode material for hydrogen production by water electrolysis according to claim 7, wherein, The electrochemical Mo doping time is 1 min.

9. An anode material for hydrogen production by water electrolysis, which is prepared by the method for preparing an anode material for hydrogen production by water electrolysis according to any one of claims 1-8.

10. The application of the anode material for hydrogen production by water electrolysis as described in claim 9 as an anode in hydrogen production by water electrolysis.

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