Anode material with multi-stage nano structure, preparation method and application

Abstract

The invention discloses an anode material with a multistage nanostructure, a preparation method and application. The anode material with the multi-stage nano structure is applied to an oxygen evolution reaction for catalyzing water electrolysis hydrogen production and can comprise a transition metal substrate, a nano columnar array formed on the transition metal substrate and a nano layered modification layer formed on the nano columnar array, the nano columnar array comprises transition metal phosphate; the nanometer layered modification layer comprises transition metal double hydroxide and cation vacancies. The anode material with the multi-stage nano structure has relatively high activity on an oxygen evolution reaction for catalyzing water electrolysis hydrogen production, the overpotential required in the oxygen evolution reaction process is relatively low, and the anode material has relatively excellent catalytic stability.

Description

Technical Field

[0001] The present invention relates to an anode material with a multi - level nanostructure, a preparation method and an application thereof. Background Art

[0002] Due to the characteristics of environmental friendliness and resource renewability of the electrolytic water hydrogen production process, it has attracted more and more attention. At present, it is found that one of the important reasons restricting the development of electrolytic water hydrogen production is the oxygen evolution reaction in electrolytic water hydrogen production. This is because the catalysts / catalytic materials for the oxygen evolution reaction used in current electrolytic water hydrogen production generally require a relatively high voltage to drive. Therefore, researching new catalysts / catalytic materials for the oxygen evolution reaction is an important direction in the field of electrolytic water.

[0003] Currently, noble metals (such as Pt, RuO2, IrO2, etc.) are mainly selected as catalysts / catalytic materials for the oxygen evolution reaction. However, noble metals not only have disadvantages such as high cost and low energy storage, but also the catalysts / catalytic materials produced using noble metals still require a relatively high over - potential to be activated. Therefore, it is very necessary to produce new catalysts / catalytic materials for the oxygen evolution reaction of electrolytic water hydrogen production. Summary of the Invention

[0004] In view of this, the present invention provides an anode material with a multi - level nanostructure, a preparation method and an application thereof. The anode material with the multi - level nanostructure forms a multi - level nanostructure through the cooperation of a nano - columnar array formed on a transition metal substrate and a nano - layered modification layer containing cation vacancies formed on the nano - columnar array. It has high activity for catalyzing the oxygen evolution reaction of electrolytic water hydrogen production, and requires a relatively low over - potential during the oxygen evolution reaction process. The anode material with the multi - level nanostructure also has relatively excellent catalytic stability.

[0005] To solve the above - mentioned technical problems, the present invention provides the following technical solutions:

[0006] In the first aspect, the present invention provides an anode material with a multi - level nanostructure, which is applied to catalyze the oxygen evolution reaction of electrolytic water hydrogen production, and includes: a transition metal substrate, a nano - columnar array formed on the transition metal substrate, and a nano - layered modification layer formed on the nano - columnar array;

[0007] In the second aspect, an embodiment of the present invention provides a preparation method of an anode material with a multi - level nanostructure, including:

[0008] Step 1: Immerse the transition metal substrate in a solution containing hydrogen phosphate ions and ammonium ions, and form a nano - columnar array containing transition metal phosphate on the transition metal substrate through a hydrothermal reaction;

[0009] Step 2: Form a nano-layered modified layer containing aluminum ions and transition metal double hydroxides on the surface of the nano-columnar array by electrodeposition;

[0010] Step 3: Immerse the transition metal substrate with the nano-layered modified layer and the nano-columnar array in a strong alkali solution to remove the aluminum ions and construct cation vacancies.

[0011] Optionally, Step 1 includes: Immerse the transition metal substrate in a solution containing hydrogen phosphate ions with a molar concentration of 0.025M - 0.1M and ammonium ions with a molar concentration of 0.05M - 0.2M, control the temperature of the hydrothermal reaction at 180°C - 220°C and the time of the hydrothermal reaction at 9h - 15h to form a nano-columnar array containing transition metal phosphates on the transition metal substrate.

[0012] In a third aspect, an embodiment of the present invention provides an application of the anode material with the multi-level nanostructure provided in the first aspect of the above invention in the oxygen evolution reaction for catalytic electrolytic water hydrogen production. The application further includes:

[0013] Use the anode material with the multi-level nanostructure as the anode for catalytic electrolytic water hydrogen production, and apply a positive electrode potential to the anode to cause surface reconstruction of the nano-layered modified layer in the anode material to expose more active sites.

[0014] The technical solution of the first aspect of the above invention has the following advantages or beneficial effects:

[0015] The anode material with the multi-level nanostructure provided by the embodiment of the present invention, through the cooperation of the nano-columnar array and the nano-layered modified layer with cation vacancies formed on the nano-columnar array, enables the anode material to have a multi-level nanostructure. This multi-level nanostructure can not only expose more active sites but also increase the contact area between the anode material and the electrolyte, making the anode material have high activity for the oxygen evolution reaction of catalytic electrolytic water hydrogen production. In addition, the anode material with this multi-level nanostructure requires a lower overpotential during the oxygen evolution reaction process and has relatively excellent catalytic stability. Description of the Drawings

[0016] Figure 1 is a schematic structural diagram drawn according to the anode material with the multi-level nanostructure of the embodiment of the present invention;

[0017] Figure 2 is a main process schematic diagram of the preparation method of the anode material with the multi-level nanostructure of the embodiment of the present invention;

[0018] Figure 3 is a scanning electron microscope image of the anode material with the multi-level nanostructure of Example 1;

[0019] Figure 4 It is a scanning electron microscope image of the nano-columnar array obtained in step A3 of Example 1;

[0020] Figure 5 It is a scanning electron microscope image of the anode material with a multi-level nanostructure of Example 1;

[0021] Figure 6 It is a transmission electron microscope image of the nano-column structure of Example 1 and the nano-layered modification layer formed on the nano-column structure;

[0022] Figure 7 It is a high-resolution transmission electron microscope image of the anode material with a multi-level nanostructure of Example 1;

[0023] Figure 8 It is an XPS graph of nickel and iron elements before and after introducing cation vacancies into the anode material with a multi-level nanostructure of Example 1 in step A5;

[0024] Figure 9 It is a comparison graph of polarization curves of the product obtained after step A4 of Example 1, the product obtained after step A5, and the catalytic material of the comparative example in an alkaline electrolyte;

[0025] Figure 10 It is a graph of the stability test results of the anode material with a multi-level nanostructure of Example 1.

[0026] The reference numerals are as follows:

[0027] 10 - Transition metal substrate; 20 - Nano-columnar array; 30 - Nano-layered modification layer. Detailed implementation manners

[0028] For the electrolytic water hydrogen production process, many existing anode catalysts for the oxygen evolution reaction still cannot well achieve the balance between the preparation process complexity and the catalytic performance. The preparation processes of many catalysts with excellent performance are relatively cumbersome, while for catalysts with simple preparation processes, the intrinsic catalytic activity and electrochemical activity are relatively poor.

[0029] For the anode oxygen evolution reaction in the electrolytic water hydrogen production process, particularly in the alkaline electrolyte environment, it is found that catalytic materials mainly composed of transition metal components such as nickel and iron can be developed to replace noble metal catalysts to reduce the cost of the catalysts.

[0030] Further research on the catalytic oxygen evolution reaction in the electrolytic water hydrogen production process reveals that in order to obtain an anode material with high-efficiency catalytic oxygen evolution, the anode material needs to have a lower overpotential per unit geometric surface area. This requires the anode material to have two characteristics simultaneously: 1. It has good intrinsic catalytic activity, that is, compared with other catalytic materials, the anode material with the same amount of substance should have higher activity; 2. It has a large electrochemical surface, that is, compared with other catalytic materials, under the same macroscopic surface area of the electrode, more anode material can be loaded or a larger active surface area can be exposed by adjusting the surface morphology, thereby increasing the number of effective catalytic sites.

[0031] Based on the above two characteristics, the embodiments of the present invention provide an anode material with a hierarchical nanostructure that can simultaneously meet the above two characteristics, a preparation method of the anode material with a hierarchical nanostructure, and an application of the anode material with a hierarchical nanostructure.

[0032] Among them, Figure 1 is a partial cross-sectional structure schematic diagram drawn according to the anode material with a hierarchical nanostructure of the embodiment of the present invention; Figure 2 is a main process schematic diagram of the preparation method of the anode material with a hierarchical nanostructure according to the embodiment of the present invention; Figures 3 to 5 is a scanning electron microscope (SEM) image of the anode material with a hierarchical nanostructure and intermediate products prepared by the preparation method of Example 1; Figure 6 is a transmission electron microscope image of the nanocolumn structure and the nano-layered modification layer formed on the nanocolumn structure according to Example 1; Figure 7 is a high-resolution transmission electron microscope image of the anode material with a hierarchical nanostructure according to Example 1; Figure 8 is an XPS image of nickel and iron elements before and after introducing cation vacancies in the anode material with a hierarchical nanostructure according to Example 1; Figure 9 is a polarization curve comparison diagram of the anode material with a hierarchical nanostructure according to Example 1 and the catalytic material of the comparative example in an alkaline electrolyte; Figure 10 is a stability test result diagram of the anode material with a hierarchical nanostructure according to Example 1.

[0033] Specifically, the embodiments of the present invention provide an anode material with a hierarchical nanostructure. The anode material with a hierarchical nanostructure is applied to the catalytic oxygen evolution reaction of electrolytic water hydrogen production. More specifically, as Figure 1 shown, the anode material with a hierarchical nanostructure may include: a transition metal substrate 10, a nano-columnar array 20 formed on the transition metal substrate 10, and a nano-layered modification layer 30 formed on the nano-columnar array 20; the nano-columnar array 20 contains transition metal phosphate; the nano-layered modification layer 30 contains transition metal double hydroxide and cation vacancies.

[0034] The anode material with a hierarchical nanostructure provided by this embodiment has a hierarchical nanostructure through the cooperation of a nano-columnar array and a nano-layered modification layer with cation vacancies formed on the nano-columnar array. This hierarchical nanostructure can not only expose more active sites but also increase the contact area between the anode material and the electrolyte, making the anode material highly active for the oxygen evolution reaction in catalytic electrolytic water for hydrogen production. In addition, the anode material with this hierarchical nanostructure requires a lower overpotential during the oxygen evolution reaction and has relatively excellent catalytic stability.

[0035] It should be noted that Figure 1 The structure shown is only an example drawn to illustrate the structure of the anode material with a hierarchical nanostructure. Figure 1 The angle between the nano-column structure in the shown nano-columnar array 20 and the transition metal substrate 10, Figure 1 the distribution of the nano-column structures in the shown nano-columnar array 20, and Figure 1 the distribution density of the nano-layered modification layer on the nano-columnar array 20, etc. do not constitute a limitation to the anode material with a hierarchical nanostructure provided by the embodiments of the present invention. Those skilled in the art can obtain the relative positional relationship between the nano-columnar array 20 and the transition metal substrate 10 (such as the distribution density of the nano-columnar array 20 on the transition metal substrate 10, the angle between the nano-column structure in the nano-columnar array 20 and the transition metal substrate 10, etc.) and the distribution of the nano-layered modification layer on the nano-columnar array 20, etc. in the anode material with a hierarchical nanostructure provided by the embodiments of the present invention by adjusting process parameters.

[0036] The anode material with a hierarchical nanostructure provided by the embodiments of the present invention mainly includes three parts: a transition metal substrate 10, a nano-columnar array 20, and a nano-layered modification layer 30. To ensure the performance of the anode material with a hierarchical nanostructure, the cooperation between these three parts is essential.

[0037] Next, the transition metal substrate 10, the nano-columnar array 20, and the nano-layered modification layer 30 will be further described separately.

[0038] Regarding the transition metal substrate 10 provided in the embodiments of the present invention, it may include at least one of nickel, iron, cobalt, copper, molybdenum, and tungsten. Preferably, the transition metal substrate 10 is a network structure or a foam structure formed by at least one of nickel, iron, cobalt, copper, molybdenum, and tungsten. By selecting the network structure or foam structure of the transition metal (at least one of nickel, iron, cobalt, copper, molybdenum, and tungsten) as the transition metal substrate 10, on the one hand, it has relatively strong self-supporting performance, enabling the anode material of the multi-level nanostructure to have strong self-supporting performance and not prone to collapse; on the other hand, the network structure or foam structure of the transition metal (at least one of nickel, iron, cobalt, copper, molybdenum, and tungsten) helps to form a nano-columnar array 20 on its surface. In addition, the anode material of the multi-level nanostructure formed based on the network structure or foam structure of the transition metal (at least one of nickel, iron, cobalt, copper, molybdenum, and tungsten) can be directly used as the anode for electrolytic water hydrogen production without loading the anode material of the multi-level nanostructure on other materials, improving the reliability and stability of the anode for electrolytic water hydrogen production.

[0039] More preferably, the above-mentioned transition metal substrate 10 may be a nickel foam substrate or a nickel grid substrate. Most preferably, the transition metal substrate 10 is a nickel foam substrate. Through research, it is found that compared with the network structures and foam structures of other transition metals and nickel mesh structures, nickel foam can provide more stable self-support and ensure the structural stability of the anode material of the multi-level nanostructure after long-term use, and is not prone to structural collapse.

[0040] More specifically, the thickness of the transition metal substrate 10 is generally 1 mm to 3 mm. Exemplarily, the thickness of the transition metal substrate 10 may be 1 mm, 1.5 mm, 2 mm, 2.5 mm, or 3 mm, etc. By limiting the thickness of the transition metal substrate 10 to 1 mm to 3 mm, the anode material of the multi-level nanostructure can be directly used as the anode for catalytic electrolytic water hydrogen production without additionally introducing other supporting materials, ensuring the integrated structure of the anode for catalytic electrolytic water hydrogen production and reducing the risk of the anode material falling off and collapsing.

[0041] Regarding the nano-columnar array 20, the nano-columnar array 20 is generally uniformly distributed on the surface of the transition metal substrate 10. Further, each nano-column structure included in the nano-columnar array 20 grows radially and uniformly in a random orientation on the surface of the transition metal substrate 10. Among them, the radial shape means that the nano-column structure epitaxially grows into a columnar structure on the surface of the transition metal substrate 10, making the nano-columnar array 20 in a radial state. In addition, the random orientation means that the angle formed by the nano-column structure and the surface of the transition metal substrate 10 is not fixed, and there is no strict growth sequence for the nano-column structures in each orientation. Although the nano-column structures grow in a random orientation on the surface of the transition metal substrate 10, it can still ensure that, based on the surface of the transition metal substrate 10, the nano-column structures growing in all directions are basically uniform. By the radially and uniformly growing of each nano-column structure included in the nano-columnar array 20 in a random orientation on the surface of the transition metal substrate 10, the uniformity of the distribution of the nano-layered modification layer 30 on the anode material is improved, the uniformity of the catalytic reaction can be ensured, and it helps to improve the gas-liquid contact.

[0042] In addition, regarding the nano-columnar array 20, the diameter of each nano-column structure included therein is generally 200 nm to 500 nm. Exemplarily, the diameter of the nano-column structure can be 200 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, etc. By controlling the diameter of the nano-column structure, the distribution uniformity and structural uniformity of the nano-column structures included in the nano-columnar array 20 can be ensured, and the distribution density of the nano-layered modification layer 30 on the nano-columnar array 20 and the nano-column structures can be increased, effectively increasing the active sites of the anode material of the multi-level nanostructure and ensuring the contact space between the nano-layered modification layer 30 and the electrolyte, which helps to improve the catalytic effect of the nano-layered modification layer 30.

[0043] Further, the transition metal in the transition metal phosphate included in the nano-columnar array 20 is the same as the transition metal in the transition metal substrate 10, and the nano-columnar array 20 and the surface of the transition metal substrate 10 are bonded by chemical bonds. Preferably, the transition metal in the transition metal phosphate included in the nano-columnar array 20 is derived from the transition metal substrate 10. More preferably, when the transition metal substrate 10 is nickel foam, the transition metal phosphate is generally nickel phosphate. The transition metal in the transition metal phosphate included in the nano-columnar array 20 is the same as the transition metal in the transition metal substrate 10, and the nano-columnar array 20 and the surface of the transition metal substrate 10 are bonded by chemical bonds. In particular, the transition metal in the transition metal phosphate is derived from the transition metal substrate 10, enabling the nano-columnar array 20 to form a stable self-supporting integrated structure with the transition metal substrate 10. More specifically, the nano-columnar array 20 is formed by etching the transition metal substrate 10 to generate free nickel atoms, and then these free nickel atoms re-grow on the surface of the transition metal substrate 10 in a hydrothermal reaction environment in cooperation with the introduced hydrogen phosphate ions to form the nano-columnar array 20. A stable chemical bond is formed between the nano-columnar array 20 and the surface of the transition metal substrate 10, ensuring the stability and reliability of the binding between the nano-columnar array 20 and the surface of the transition metal substrate 10.

[0044] Further, for the nano-layered modification layer 30 included in the anode material of the multi-level nanostructure provided in the embodiment of the present invention, the transition metal double hydroxide it includes is generally a chemical structure with a flaky morphology formed by the combination of transition metal ions and hydroxide ions. More specifically, the transition metal double hydroxide generally contains two or more kinds of transition metal ions. Preferably, the transition metal double hydroxide may include at least two of the following transition metal ions: nickel ion, ferrous ion, ferric ion, aluminum ion, cobalt ion, molybdenum ion, tungsten ion, copper ion, ruthenium ion, platinum ion, iridium ion, rhodium ion, gold ion, and silver ion. More preferably, the transition metal double hydroxide is generally nickel-iron double hydroxide. It has been found that the nickel-iron double hydroxide can form a stable bond with the nano-columnar array 20, effectively reducing the risk of detachment of the nano-layered modification layer 30 and ensuring the stability and reliability of the multi-level nanostructure.

[0045] In addition, as Figure 1 shown, the nano-layered modification layer 30 includes a nano-sheet structure laid in layers. In addition to arranging on the nano-columnar array 20, there will be partial overlapping layers between the nano-sheet structures. Therefore, in Figure 6The nano-layered modification layer 30 captured by transmission electron microscopy is essentially formed by laying nano-sheet structures and partially overlapping and stacking them between the nano-sheet structures. The nano-sheet structures laid in this way enable the anode material of the multi-level nanostructure to have a richer surface and better contact with the electrolyte.

[0046] Among them, the width of the nano-sheet structures included in the nano-layered modification layer 30 is generally 50 nm to 100 nm. Exemplarily, as Figure 1 shown, the width W of the nano-sheet structures included in the nano-layered modification layer 30 is generally the distance between any one edge point on the included nano-sheet structure and the edge point farthest from that edge point. Exemplarily, the width of the included nano-sheet structures can be 50 nm, 70 nm, 80 nm, 90 nm, 100 nm, etc. By controlling the width of the included nano-sheet structures, it is ensured that the formed nano-layered modification layer 30 makes full contact with the electrolyte, improving the catalytic performance of the anode material of the multi-level nanostructure.

[0047] It should be noted that Figure 1 the given nano-sheet structure is only an example, and the specific shape of the nano-sheet structure is related to the type of transition metal in the transition metal double hydroxide. The specific shape of the nano-sheet structure is not limited here.

[0048] For the anode material of the multi-level nanostructure provided in each of the above embodiments of the present invention, the nano-layered modification layer 30 included therein is its main catalytic activity source, while the main function of the nano-columnar array 20 is to serve as a load matrix for the nano-layered modification layer 30. Compared with the nano-layered modification layer 30 directly formed on the foam structure or network structure of the transition metal, the nano-columnar array 20 can effectively increase the surface area of contact between the nano-layered modification layer 30 and the electrolyte, and the introduction of the nano-columnar array 20 can also improve the gas-liquid contact during the catalytic process. In addition, the nano-columnar array 20 forms good ohmic contact and mechanical strength with the foam structure or network structure of the transition metal, ensuring the conductivity, self-supporting stability and reliability of the anode material of the multi-level nanostructure, and reducing the risk of structure collapse.

[0049] In addition, by introducing cation vacancies, the nano-layered modification layer 30 can further improve the intrinsic activity and stability of the nano-layered modification layer 30.

[0050] Furthermore, the nano-layered modification layer 30 contains amorphous transition metal double hydroxide, and this amorphous state can increase the disorder of atomic arrangement in the nano-layered modification layer 30, which is beneficial to improving the catalytic performance of the nano-layered modification layer 30.

[0051] Specifically, for the nickel foam as the transition metal substrate 10, the nano-columnar array 20 formed by the nano-columnar structure mainly composed of nickel phosphate is used as the loading matrix of the nano-layered modification layer 30, and the nano-layered modification layer 30 (NiFe-LDH) containing cation vacancies and nickel-iron double hydroxide is used as the main catalytic activity source. Compared with other transition metals, nickel foam can form a better ohmic contact with the nano-columnar array 20 mainly composed of nickel phosphate, and the formed structure has higher mechanical strength. Moreover, the nano-columnar array 20 mainly composed of nickel phosphate can better improve the gas-liquid contact during the catalytic process, and the nano-layered modification layer 30 (NiFe-LDH) containing cation vacancies and nickel-iron double hydroxide also has higher intrinsic activity and stability.

[0052] Further, for the anode material with the above-mentioned multi-level nanostructure, in an alkaline solution and at a current density of 10 mA / cm 2 the overpotential is lower than 200 mV.

[0053] In addition, for the anode material with the above-mentioned multi-level nanostructure, in an alkaline solution and at a current density of 100 mA / cm 2 the overpotential is lower than 230 mV. Therefore, the anode material with the multi-level nanostructure can improve the catalytic efficiency and reduce the energy consumption.

[0054] Further, the embodiment of the present invention also provides a preparation method of an anode material with a multi-level nanostructure. As Figure 2 shown, the preparation method may include the following steps:

[0055] Step S201: Immerse the transition metal substrate 10 in a solution containing hydrogen phosphate ions and ammonium ions, and form a nano-columnar array 20 containing transition metal phosphate on the transition metal substrate 10 through a hydrothermal reaction.

[0056] The transition metal substrate 10 may be a network structure or a foam structure formed by at least one of nickel, iron, cobalt, copper, molybdenum, and tungsten. Preferably, the transition metal substrate 10 is generally nickel foam. Through research, it is found that compared with the network structure and foam structure of other transition metals and the nickel mesh structure, nickel foam can provide more stable self-support and can ensure the structural stability of the anode material with a multi-level nanostructure after long-term use, and it is not easy to collapse.

[0057] During the hydrothermal reaction in step S201, there are mainly two processes between the solution of hydrogen phosphate ions and ammonium ions and the transition metal substrate 10: one process is that the transition metal substrate 10 is etched to generate free transition metal ions; the other process is that a nano-columnar structure containing transition metal phosphate grows on the transition metal substrate 10 to form a nano-columnar array 20. Among them, the process of etching the transition metal substrate 10 and the process of growing the nano-columnar structure generally proceed synchronously to effectively control the nano-columnar structure and the nano-columnar array 20. Preferably, when the transition metal substrate 10 is nickel foam, the transition metal phosphate is generally nickel phosphate.

[0058] Step S202: By electrodeposition, a nano-layered modification layer 30 containing aluminum ions and transition metal double hydroxides is formed on the surface of the nano-columnar array 20.

[0059] This transition metal double hydroxide generally contains two or more transition metal ions. Preferably, the transition metal double hydroxide can include at least two of the following transition metal ions: nickel ions, ferrous ions, ferric ions, aluminum ions, cobalt ions, molybdenum ions, tungsten ions, copper ions, ruthenium ions, platinum ions, iridium ions, rhodium ions, gold ions, and silver ions. More preferably, the transition metal double hydroxide is generally nickel-iron double hydroxide. It has been found that this nickel-iron double hydroxide can form a stable bond with the nano-columnar array 20, effectively reducing the risk of shedding of the nano-layered modification layer 30 and ensuring the stability and reliability of the multi-level nanostructure.

[0060] Step S203: The transition metal substrate 10 with the nano-layered modification layer and the nano-columnar array 20 is soaked in a strong base solution to remove aluminum ions and construct cation vacancies.

[0061] The preparation method provided by the embodiments of the present invention has simple steps and scalability. The anode material with a multi-level nanostructure of the required size can be obtained by expanding the scale of the hydrothermal reaction and electrodeposition. Moreover, each of the above steps has a relatively wide industrial window, enabling the industrialization of the production of the anode material with a multi-level nanostructure.

[0062] In addition, for the anode material with a multi-level nanostructure prepared by this preparation method, through the cooperation of the nano-columnar array and the nano-layered modification layer with cation vacancies formed on the nano-columnar array, the anode material has a multi-level nanostructure. This multi-level nanostructure can not only expose more active sites but also increase the contact area between the anode material and the electrolyte, making the anode material have high activity for the oxygen evolution reaction in catalytic electrolytic water for hydrogen production. In addition, for the anode material with this multi-level nanostructure, the overpotential required during the oxygen evolution reaction process is low, and it has relatively excellent catalytic stability.

[0063] Specifically, for the above-mentioned step S201, a specific implementation thereof may include: immersing the transition metal substrate 10 in a solution containing hydrogen phosphate ions with a molar concentration of 0.025M to 0.1M (M represents mol / L) and ammonium ions with a molar concentration of 0.05M to 0.2M, controlling the temperature of the hydrothermal reaction at 180°C to 220°C and the time of the hydrothermal reaction at 9h to 15h, to form a nano-columnar array 20 containing transition metal phosphate on the transition metal substrate 10. Exemplarily, the molar concentration of hydrogen phosphate ions contained in the solution used in the hydrothermal reaction of this step S201 may be 0.025M, 0.05M, 0.07M, 0.09M or 0.1M, etc. The molar concentration of ammonium ions contained in the solution used in the hydrothermal reaction of this step S201 may be 0.05M, 0.1M, 0.14M, 0.18M or 0.2M, etc. The temperature of the hydrothermal reaction may be 180°C, 190°C, 200°C, 220°C. The time of the hydrothermal reaction may be 9h, 10h, 11h, 12h, 14h or 15h, etc. By controlling the conditions of the hydrothermal reaction (such as the molar concentration of hydrogen phosphate ions, ammonium ions, the temperature of the hydrothermal reaction, and the time of the hydrothermal reaction, etc.), the uniform growth of the nano-columnar array and the nano-column structure can be ensured. Exemplarily, hydrogen phosphate ions and ammonium ions can be obtained from an aqueous solution of diammonium hydrogen phosphate.

[0064] For the above-mentioned step S202, a specific implementation thereof may include: using a solution containing nitrate ions, nickel ions, ferrous ions, and aluminum ions as the precursor solution for electrodeposition, using a three-electrode device or a two-electrode constant current device, taking the transition metal substrate 10 with the nano-columnar array 20 as one electrode, and controlling the electrodeposition time at 5 min to 15 min to obtain a nano-layered modified layer containing aluminum ions and transition metal double hydroxides.

[0065] Specifically, for the case of using a three-electrode device, taking the transition metal substrate 10 with the nano-columnar array 20 as the working electrode of the three-electrode device, a carbon rod as the counter electrode, and silver-silver chloride in a saturated chloride solution as the reference electrode, after depositing at a voltage of -0.8V to -1V for 5 min to 15 min, a nano-layered modified layer containing aluminum ions and transition metal double hydroxides is obtained. Exemplarily, the voltage of the three-electrode device may be -0.8V, -0.9V or -1.0V, etc., and the deposition time may be 5 min, 8 min, 10 min, 12 min or 15 min, etc.

[0066] In addition, for the case of using a two-electrode constant current device, the transition metal substrate 10 with the nano-columnar array 20 is placed in the electrolyte solution with a fixture. Among them, the anode of the two-electrode constant current device is a copper plate with an area larger than that of the transition metal substrate 10, and the current density of the two-electrode constant current device is 10 mA·cm-2 ~20 mA·cm -2 , the electrodeposition time is 5 min to 15 min, and the electrodeposition temperature is 10°C to 60°C. Among them, the fixture is a copper fixture or a titanium fixture. Exemplarily, the current density of the two-electrode constant current device can be 10 mA·cm -2 , 12 mA·cm -2 , 15 mA·cm -2 or 20 mA·cm -2 etc., the electrodeposition time can be 5 min, 8 min, 10 min, 12 min or 15 min etc., and the electrodeposition temperature can be 10°C, 30°C, 40°C, 50°C or 60°C etc.

[0067] Among them, the molar concentration ranges of nitrate ions, nickel ions, ferrous ions and aluminum ions are: nitrate ions 0.05 M to 0.1 M, nickel ions 0.05 M to 0.1 M, ferrous ions 0.05 M to 0.1 M, and aluminum ions 0.0005 M to 0.002 M. Exemplarily, the molar concentration of nitrate ions can be 0.05 M, 0.08 M or 0.1 M etc., the molar concentration of nickel ions can be 0.05 M, 0.08 M or 0.1 M etc., the molar concentration of ferrous ions can be 0.05 M, 0.08 M or 0.1 M etc., and the molar concentration of aluminum ions can be 0.0005 M, 0.0008 M, 0.001 M or 0.002 M etc.

[0068] As can be seen from the above, the preparation method of the anode material with a multi-level nanostructure provided by the embodiments of the present invention is mainly divided into three parts:

[0069] The first part is to in-situ etch and grow a nano-columnar array with the main component of transition metal phosphate on the transition metal substrate. Among them, the transition metal comes from the transition metal substrate; this in-situ etching and growth can ensure the structural strength of the formed nano-columnar array on the transition metal substrate, making the nano-columnar array not easy to fall off, and can also make the nano-columnar array bind more tightly to the transition metal substrate, without forming an obvious interface between the nano-columnar array and the transition metal substrate, so that a good ohmic contact is formed between the nano-columnar array and the transition metal substrate. In addition, this process does not introduce extra nickel ions, and adding extra nickel ions will instead cause solution precipitation, which is not conducive to the growth of the nano-columnar array. Further, this nano-columnar array can well increase the surface area, load more nano-layered modification layers formed in the second part, and at the same time can improve the contact with the electrolyte. In addition, this nano-columnar array can enhance the hydrophilicity of the anode material, improve the contact performance between the anode material and the liquid, and repel bubbles, thus facilitating the discharge of bubbles during the catalytic process.

[0070] The second part is to electrochemically deposit a nano-layered modification layer on the nano-columnar array. This nano-layered modification layer is the main active source for the oxygen evolution reaction in catalytic water electrolysis for hydrogen production. It serves as the basis for the cation vacancies in the subsequent third part and can ensure the structural stability of the subsequent formation of cation vacancies without collapse.

[0071] The third part is to form cation vacancies on the nano-layered modification layer by etching. These cation vacancies further enhance the intrinsic activity of the anode material with a multi-level nanostructure and simultaneously improve the catalytic stability and reliability of the anode material with a multi-level nanostructure.

[0072] Furthermore, the embodiments of the present invention also provide an application of the anode material with a multi-level nanostructure provided in the above embodiments or the anode material with a multi-level nanostructure prepared by the above preparation method. This anode material with a multi-level nanostructure is generally applied to the oxygen evolution reaction in catalytic water electrolysis for hydrogen production. Specifically, for the application of the anode material with a multi-level nanostructure, it further includes: using the anode material with a multi-level nanostructure as the anode for catalytic water electrolysis for hydrogen production, and applying a positive electrode potential to the anode to cause surface reconstruction of the nano-layered modification layer in the anode material to expose more active sites.

[0073] As the anode for catalytic water electrolysis for hydrogen production, the electrolyte used for this anode material with a multi-level nanostructure is an alkaline electrolyte.

[0074] The alkaline electrolyte can be an aqueous solution of potassium hydroxide or sodium hydroxide with a concentration of 1-3M.

[0075] The surface reconstruction of the nano-layered modification layer in the above anode material means that after applying a positive electrode potential to the anode, the transition metal is oxidized (for example, zero-valent nickel, divalent nickel ions, and divalent ferrous ions will all be partially oxidized to trivalent). The oxidized transition metal is the active site for catalysis. Through this reconstruction process, the active sites of the anode material with a multi-level nanostructure are increased, and its catalytic performance is improved.

[0076] It should be noted that after stopping the catalysis, some of the oxidized transition metals in the anode material will return to their original valence states (such as divalent nickel ions and divalent ferrous ions).

[0077] The following uses several specific embodiments to detail the preparation process provided by the embodiments of the present invention and the performance of the prepared anode material with a multi-level nanostructure.

[0078] Example 1:

[0079] Step A1: Clean the nickel foam with dilute hydrochloric acid, ethanol, and deionized water for 10 minutes respectively to remove surface oil stains and oxide layers.

[0080] Step A2: Prepare an aqueous solution of diammonium hydrogen phosphate with a molar concentration of 0.05 M to obtain an aqueous solution containing hydrogen phosphate ions and ammonium ions.

[0081] Step A3: Immerse the cleaned nickel foam in the aqueous solution containing hydrogen phosphate ions and ammonium ions, and carry out a hydrothermal reaction at 180 °C for 12 h. Cool and dry the hydrothermal reaction product to obtain a nickel phosphate nanocolumnar array grown on the surface of the nickel foam.

[0082] Step A4: Use a mixed solution containing nickel nitrate with a molar concentration of 0.05 M, ammonium ferrous sulfate with a molar concentration of 0.05 M, and aluminum nitrate with a molar concentration of 0.001 M as the electrodeposition precursor solution. Add the electrodeposition precursor solution to a three-electrode device. Use the nickel foam with a nickel phosphate nanocolumnar array grown on its surface as the working electrode of the three-electrode device, a carbon rod as the counter electrode of the three-electrode device, and silver-silver chloride in a saturated potassium chloride solution as the reference electrode of the three-electrode device. After depositing at -1 V for 600 s, take out the working electrode, rinse it with deionized water and ethanol, and dry it. A nanolayered modified layer with NiFe-LDH is deposited on the nickel phosphate nanocolumnar array. The product formed in this step is denoted as nickel phosphate-NiFeLDH.

[0083] Step A5: After taking out the working electrode in Step A4, immerse it in a sodium hydroxide solution with a molar concentration of 5 M for 24 h, and stir while immersing to fully corrode the aluminum ions contained in NiFe-LDH to construct cation vacancies. Then take it out, rinse and dry it to finally obtain a multi-level nanostructured anode material. The multi-level nanostructured anode material forms cation vacancies and is denoted as nickel phosphate-NiFe vac LDH.

[0084] Example 2:

[0085] Step B1: Clean the nickel foam with dilute hydrochloric acid, ethanol, and deionized water for 20 min respectively to remove surface oil stains and oxide layers.

[0086] Step B2: Prepare an aqueous solution containing 0.1 M hydrogen phosphate ions and 0.2 M ammonium ions.

[0087] Step B3: Immerse the cleaned nickel foam in the aqueous solution containing hydrogen phosphate ions and ammonium ions, and carry out a hydrothermal reaction at 200 °C for 10 h. Cool and dry the hydrothermal reaction product to obtain a nickel phosphate nanocolumnar array grown on the surface of the nickel foam.

[0088] Step B4: Use a mixed solution containing nickel nitrate with a molar concentration of 0.1 M, ammonium ferrous sulfate with a molar concentration of 0.1 M, and aluminum nitrate with a molar concentration of 0.001 M as the electrodeposition precursor solution. Add the electrodeposition precursor solution to a three-electrode device. Use nickel foam with nickel phosphate nanocolumn arrays grown on its surface as the working electrode of the three-electrode device, a carbon rod as the counter electrode of the three-electrode device, and silver-silver chloride in saturated potassium chloride solution as the reference electrode of the three-electrode device. After depositing for 300 s at -1 V, take out the working electrode, rinse it with deionized water and ethanol, and then dry it. A NiFe-LDH nanolayered modification layer is deposited on the nickel phosphate nanocolumn arrays.

[0089] Step B5: After taking out the working electrode in Step B4, soak it in a sodium hydroxide solution with a molar concentration of 5 M for 24 h, and stir while soaking to fully corrode the aluminum ions contained in NiFe-LDH and construct cation vacancies. Then take it out, rinse it, and dry it. Finally, obtain an anode material with a hierarchical nanostructure.

[0090] Example 3

[0091] The difference from Example 1 is that in Step C3, the hydrothermal reaction is carried out at 190 °C for 10 h, and the electrodeposition precursor solution used in Step C4 contains nickel nitrate with a molar concentration of 0.075 M, ammonium ferrous sulfate with a molar concentration of 0.025 M, and aluminum nitrate with a molar concentration of 0.001 M.

[0092] Example 4

[0093] The difference from Example 1 is that in Step D3, the hydrothermal reaction is carried out at 220 °C for 12 h, and the electrodeposition precursor solution used in Step D4 contains nickel nitrate with a molar concentration of 0.05 M, ammonium ferrous sulfate with a molar concentration of 0.05 M, and aluminum nitrate with a molar concentration of 0.002 M.

[0094] Example 5

[0095] The difference from Example 1 is that in Step E3, the hydrothermal reaction is carried out at 220 °C for 15 h, and the electrodeposition precursor solution used in Step E4 contains nickel nitrate with a molar concentration of 0.09 M, ammonium ferrous sulfate with a molar concentration of 0.01 M, and aluminum nitrate with a molar concentration of 0.002 M.

[0096] Comparative Example:

[0097] Step F1: Clean the nickel foam with dilute hydrochloric acid, ethanol, and deionized water for 10 min respectively to remove surface oil stains and oxide layers.

[0098] Step F2, immersing the nickel foam in a solution containing 0.05M nickel nitrate and 0.05M ammonium ferrous sulfate, and performing a hydrothermal reaction at 180° C. for 12 hours, cooling and drying the hydrothermal reaction product, and growing nickel iron phosphate double hydroxide on the surface of the nickel foam.

[0099] Through testing the products obtained from the above embodiments, it is found that the structures of the products obtained from the above embodiments are basically consistent, the elements are evenly distributed, and the obtained products illustrate that the process stability and process reliability of the technical solution provided by the embodiments of the present invention are relatively high.

[0100] Therefore, in the present embodiment, the product obtained in Example 1 (a multi-level nanostructured anode material having a nano-layered modified layer of NiFe-LDH and a nickel phosphate nano-columnar array) is further taken as an example to characterize the structure of the multi-level nanostructured anode material and the valence changes of the iron and nickel elements before and after step A5 (i.e., before and after the multi-level nanostructured anode material constructs cation vacancies). Figures 3 to 5 The scanning electron microscope image (SEM image for short) shown in Figure 6 The transmission electron microscope image (TEM image) shown in Figure 7 The high-resolution transmission electron microscopy image (abbreviated as high-resolution transmission electron microscopy image) shown in the figure; for valence state changes, such as Figure 8 XPS graph shown.

[0101] in, Figure 3 and Figure 4 The scanning electron microscope images of the nickel phosphate nanocolumn arrays of different sizes grown on the surface of the nickel foam obtained after the treatment in step A3 are shown. Figure 3 and Figure 4 It can be seen that the nickel phosphate grown on the surface of the nickel foam is in the form of a nano-columnar array, and the nano-columnar array grows uniformly in all directions on the surface of the nickel foam.

[0102] Further, according to Figure 5 The scanning electron microscope image of the product obtained after step A5 is shown and Figure 6 The transmission electron micrograph of the product obtained after step A5 is shown. Figure 5 and Figure 6 It can be seen that NiFe vac LDH is uniformly and stacked in nanoscale flakes on the nanocolumn structure to form a multi-level structure. The formation of this multi-level structure effectively increases the electrochemical surface area.

[0103] Furthermore, combined with Figure 6 Transmission electron microscopy images and Figure 7 It can be seen from the high-resolution transmission electron microscopy image that NiFe vacThe LDH is in a mixed state of crystalline and amorphous phases. The introduction of cation vacancies increases the disorder of the atomic arrangement of NiFe vac LDH, thereby promoting surface reconstruction during the catalytic process (applying the positive electrode potential to NiFe vac LDH, driving the reconstruction of its atomic arrangement), making NiFe vac LDH expose more active sites, and it is found through subsequent stability tests that the structure and performance of these active sites are relatively stable.

[0104] Furthermore, the nickel and iron elements in NiFe-LDH and NiFe vac LDH in Example 1 were respectively detected by X-ray photoelectron spectroscopy (XPS), and the Figure 8 XPS spectra shown were obtained. Figure 8 Figure a and Figure b in it respectively represent the energy spectra of nickel element and iron element in NiFe-LDH (i.e., before the introduction of cation vacancies); Figure 8 Figure c and Figure d in it respectively represent the energy spectra of nickel element and iron element in NiFe vac LDH (i.e., after the introduction of cation vacancies). It can be seen from Figure 8 that most of the Ni and Fe elements are in their divalent oxidation states, and after the introduction of cation vacancies, the peak binding energies of the Ni and Fe spectra both have a small negative shift. This change reflects the increase in local electron concentration, which can bring a gain to the activity of the catalytic reaction and enhance the in-situ active catalysis.

[0105] Furthermore, in order to illustrate the catalytic performance of the anode material with a multi-level nanostructure provided by the embodiments of the present invention and the influence of the introduction of cation vacancies on the catalytic performance, the polarization curves of the product of Example 1 (nickel phosphate - NiFe vac LDH), the product obtained in step A4 of Example 1 (nickel phosphate - NiFeLDH), and the product of the comparative example (i.e., the traditional hydrothermal method) in 1M KOH electrolyte are as shown in Figure 9 . Figure 9 In it, the red curve represents the voltage-current polarization curve of the product of the comparative example, the blue curve represents the voltage-current polarization curve of the product obtained in step A4 (nickel phosphate - NiFeLDH), and the green curve represents the voltage-current polarization curve of the product obtained in step A5 of Example 1 (nickel phosphate - NiFe vac LDH). At the same current density, the electrode voltages of nickel phosphate - NiFe vac LDH, nickel phosphate - NiFeLDH, and the product of the comparative example increase. And at the same electrode voltage, nickel phosphate - NiFevac The current density of LDH is the largest. It shows that the technical solution provided by the embodiment of the present invention effectively reduces the overpotential and catalytic energy consumption by introducing cation vacancies. In addition, at the same voltage, the larger current density (catalytic current) indicates that the catalytic current is larger and the oxygen generation rate is faster. Since the current density is positively correlated with the activity, it also shows that the anode material with a multi-level nanostructure of a nano-columnar array, a nano-layered modification layer, and cation vacancies has higher intrinsic catalytic activity and electrochemical activity.

[0106] The product of Example 1 (nickel phosphate-NiFe vac LDH), the product obtained in step A4 of Example 1 (nickel phosphate-NiFe LDH), and the product of the comparative example (i.e., the traditional hydrothermal method) were further tested for the overpotential required to reach different catalytic current densities in a 1M KOH electrolyte, and the results are shown in Table 1.

[0107]

[0108] It can be seen from the results in Table 1 that the anode material with a multi-level nanostructure provided by the embodiment of the present invention, through the cooperation of the transition metal substrate 10, the nano-columnar array 20, the nano-layered modification layer 30, and cation vacancies, can effectively reduce the overpotential required for the anode material with a multi-level nanostructure during the catalytic process, indicating that the anode material with a multi-level nanostructure in the embodiment of the present invention has low energy consumption and higher catalytic efficiency during the catalytic process.

[0109] Furthermore, the performance and structural stability of the product of step A5 of Example 1 (nickel phosphate-NiFe vac LDH) were tested. Specifically, as Figure 10 shown, Figure 10 Figure a in vac shows the voltage stability of nickel phosphate-NiFe 2 LDH at a current density of 0.2 A / cm vac (nickel phosphate-NiFe 2 LDH continuously operates for 6×10 4 s at a catalytic current density of 0.2 A / cm Figure 10 in a KOH electrolyte with a molar concentration of 1M); vac Figure b in vac shows the voltage-current polarization curves of nickel phosphate-NiFe Figure 10 LDH before the stability test in Figure a and after the stability test in Figure a of nickel phosphate-NiFe vac LDH; Figure 10 Figure c invac Scanning electron microscope image of the LDH after the stability test of Figure a was completed.

[0110] Since the catalytic current is related to the oxygen evolution at the anode, the greater the current, the faster the oxygen evolution. As can be seen from Figure 10 Figure a, at a relatively high catalytic current, this nickel phosphate-NiFe vac LDH has relatively high catalytic stability. Moreover Figure 10 as can be seen from Figure b, for this nickel phosphate-NiFe vac LDH, before and after the stability test, the voltage and current of the nickel phosphate-NiFe vac LDH change little, further indicating that the nickel phosphate-NiFe vac LDH has strong catalytic stability. In addition, by comparing Figure 10 Figures c and d, it can also be seen that before and after the stability test, the structure of the nickel phosphate-NiFe vac LDH does not change significantly, indicating that the structure of the nickel phosphate-NiFe vac LDH is stable and will not collapse after the catalytic process.

[0111] In summary, the anode material with a hierarchical nanostructure provided by the embodiments of the present invention, through the cooperation of a nano-columnar array and a nano-layered modification layer with cation vacancies formed on the nano-columnar array, enables the anode material to have a hierarchical nanostructure. This hierarchical nanostructure can not only expose more active sites but also increase the contact area between the anode material and the electrolyte, enabling the anode material to have high intrinsic catalytic activity and electrochemical activity for the oxygen evolution reaction in catalytic electrolytic water hydrogen production. In addition, this anode material with a hierarchical nanostructure requires a lower overpotential during the oxygen evolution reaction process and has relatively excellent catalytic stability and structural stability.

[0112] In summary, the embodiments of the present invention provide the following technical solutions:

[0113] Technical Solution 1: An anode material with a hierarchical nanostructure for use in the oxygen evolution reaction of catalytic electrolytic water hydrogen production, comprising: a transition metal substrate 10, a nano-columnar array 20 formed on the transition metal substrate 10, and a nano-layered modification layer 30 formed on the nano-columnar array 20;

[0114] The nano-columnar array 20 contains transition metal phosphate;

[0115] The nano-layered modification layer 30 contains transition metal double hydroxide and cation vacancies.

[0116] Technical Solution 2: The anode material with a hierarchical nanostructure according to Technical Solution 1,

[0117] The nano-columnar arrays 20 are uniformly distributed on the surface of the transition metal substrate 10;

[0118] and / or,

[0119] Each nano-column structure included in the nano-columnar arrays 20 grows radially and uniformly in a random orientation on the surface of the transition metal substrate 10.

[0120] Technical solution 3: The anode material with a multi-level nanostructure according to Technical solution 1,

[0121] The diameter of each nano-column structure included in the nano-columnar arrays 20 is 200 nm to 500 nm.

[0122] Technical solution 4: The anode material with a multi-level nanostructure according to Technical solution 1,

[0123] The nano-layered modification layer 30 includes a nano-sheet structure laid in layers.

[0124] Technical solution 5: The anode material with a multi-level nanostructure according to Technical solution 4,

[0125] The width of the nano-sheet structure is 50 nm to 100 nm;

[0126] and / or,

[0127] The nano-layered modification layer 30 contains an amorphous transition metal double hydroxide.

[0128] Technical solution 6: The anode material with a multi-level nanostructure according to any one of Technical solutions 1 to 5,

[0129] The transition metal substrate 10 is a foam structure or a mesh structure.

[0130] Technical solution 7: The anode material with a multi-level nanostructure according to Technical solution 6,

[0131] The transition metal substrate 10 is a foam structure nickel substrate or a grid structure nickel substrate.

[0132] Technical solution 8: The anode material with a multi-level nanostructure according to Technical solution 6,

[0133] The thickness of the transition metal substrate 10 is 1 mm to 3 mm.

[0134] Technical solution 9: The anode material with a multi-level nanostructure according to Technical solution 6,

[0135] The transition metal phosphate is nickel phosphate.

[0136] Technical solution 10. The anode material with a multi-level nanostructure according to technical solution 6,

[0137] wherein the transition metal double hydroxide is nickel-iron double hydroxide.

[0138] Technical solution 11. The anode material with a multi-level nanostructure according to any one of technical solutions 1 to 5, 7 to 10,

[0139] in an alkaline solution and at a current density of 10 mA / cm 2 the overpotential of the anode material with the multi-level nanostructure is lower than 200 mV.

[0140] Technical solution 12. The anode material with a multi-level nanostructure according to any one of technical solutions 1 to 5, 7 to 10,

[0141] in an alkaline solution and at a current density of 100 mA / cm 2 the overpotential of the anode material with the multi-level nanostructure is lower than 230 mV.

[0142] Technical solution 13. The anode material with a multi-level nanostructure according to technical solution 1,

[0143] the transition metal in the transition metal phosphate contained in the nano-columnar array 20 is the same as the transition metal in the transition metal substrate 10, and the nano-columnar array 20 and the surface of the transition metal substrate 10 are bonded by chemical bonds.

[0144] Technical solution 14. The anode material with a multi-level nanostructure according to technical solution 13,

[0145] the transition metal in the transition metal phosphate contained in the nano-columnar array 20 is derived from the transition metal substrate 10.

[0146] Technical solution 15. A preparation method of an anode material with a multi-level nanostructure, comprising:

[0147] Step 1. Immerse the transition metal substrate 10 in a solution containing hydrogen phosphate ions and ammonium ions, and form a nano-columnar array 20 containing transition metal phosphate on the transition metal substrate 10 through a hydrothermal reaction;

[0148] Step 2. Form a nano-layered modification layer containing aluminum ions and transition metal double hydroxide on the surface of the nano-columnar array 20 by an electrodeposition method;

[0149] Step 3. Immerse the transition metal substrate 10 with the nano-layered modification layer and the nano-columnar array 20 in a strong alkaline solution to remove the aluminum ions and construct cation vacancies.

[0150] Technical solution 16. The preparation method according to technical solution 15,

[0151] Step 1 includes: immersing the transition metal substrate 10 in a solution containing phosphate ions with a molar concentration of 0.025M to 0.1M and ammonium ions with a molar concentration of 0.05M to 0.2M, controlling the temperature of the hydrothermal reaction at 180°C to 220°C and the time of the hydrothermal reaction at 9h to 15h, and forming a nano-columnar array 20 containing transition metal phosphate on the transition metal substrate 10.

[0152] Technical solution 17. The preparation method according to technical solution 15 or 16,

[0153] Step 2 includes: using a solution containing nitrate ions, nickel ions, ferrous ions, and aluminum ions as the precursor solution for electrodeposition, using a three-electrode device or a two-electrode constant current device, taking the transition metal substrate 10 with the nano-columnar array 20 as one electrode, and controlling the electrodeposition time at 5min to 15min to obtain a nano-layered modified layer containing aluminum ions and transition metal double hydroxides.

[0154] Technical solution 18. The preparation method according to technical solution 17,

[0155] Step 2 includes: for the case of using a three-electrode device, taking the transition metal substrate 10 with the nano-columnar array 20 as the working voltage of the three-electrode device, using a carbon rod as the counter voltage, and silver-silver chloride in a saturated chloride salt solution as the reference electrode. After depositing at a voltage of -0.8 to -1V for 5min to 15min, a nano-layered modified layer containing aluminum ions and transition metal double hydroxides is obtained.

[0156] Technical solution 19. The preparation method according to technical solution 17,

[0157] Step 2 includes: for the case of using a two-electrode constant current device, putting the transition metal substrate 10 with the nano-columnar array 20 into the electrolyte solution with a fixture. Among them, the anode of the two-electrode constant current device is a copper plate with an area larger than the transition metal substrate 10, and the current density of the two-electrode constant current device is 10mA·cm -2 ~20mA·cm -2 , the electrodeposition time is 5min to 15min, and the electrodeposition temperature is 10°C to 60°C. Among them, the fixture is a copper fixture or a titanium fixture.

[0158] Technical solution 20. The preparation method according to technical solution 17,

[0159] The molar concentration ranges of nitrate ions, nickel ions, ferrous ions and aluminum ions are as follows: nitrate ions 0.05M - 0.1M, nickel ions 0.05M - 0.1M, ferrous ions 0.05M - 0.1M, and aluminum ions 0.0005M - 0.002M.

[0160] Technical solution 21. The application of the anode material with a multi - level nanostructure according to any one of technical solutions 1 to 14 is applied to the oxygen evolution reaction of catalytic electrolytic water for hydrogen production. The application further includes:

[0161] Using the anode material with a multi - level nanostructure as the anode for catalytic electrolytic water for hydrogen production, and applying a positive electrode potential to the anode to cause surface reconstruction of the nano - layered modification layer in the anode material to expose more active sites.

[0162] The introduction provided in the above steps is only used to help understand the method, structure and core idea of the present invention. For those of ordinary skill in the art of this technology, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A multi-level nanostructured anode material, characterized in that: The invention is applied to the oxygen evolution reaction of catalyzing the electrolysis of water to produce hydrogen, comprising: a transition metal substrate (10), a nano-column array (20) formed on the transition metal substrate (10), and a nano-layered modified layer (30) formed on the nano-column array (20); The nanocolumnar array (20) comprises a transition metal phosphate; The nano-layered modified layer (30) contains transition metal double hydroxide and cation vacancies.

2. The multi-level nanostructured anode material according to claim 1, characterized in that: The nanocolumnar array (20) is evenly distributed on the surface of the transition metal substrate (10); and / or, Each nano-column structure included in the nano-column array (20) grows uniformly in a randomly oriented radial manner on the surface of the transition metal substrate (10).

3. The multi-level nanostructured anode material according to claim 1, characterized in that: The diameter of each nano-column structure included in the nano-column array (20) is 200 nm to 500 nm.

4. The multi-level nanostructured anode material according to claim 1, characterized in that: The nano-layered modified layer (30) comprises a stacked nano-sheet structure.

5. The multi-level nanostructured anode material according to claim 4, characterized in that: The width of the nanosheet structure is 50nm~100nm; and / or, The nano-layered modified layer (30) contains amorphous transition metal double hydroxide.

6. The multi-level nanostructured anode material according to any one of claims 1 to 5, characterized in that: The transition metal substrate (10) is a foam structure or a mesh structure.

7. The multi-level nanostructured anode material according to claim 6, characterized in that: The transition metal phosphate is nickel phosphate; and / or, The transition metal double hydroxide is nickel-iron double hydroxide.

8. The multi-level nanostructured anode material according to claim 1, characterized in that: The transition metal in the transition metal phosphate contained in the nano-columnar array (20) is the same as the transition metal in the transition metal substrate (10), and the nano-columnar array (20) is bonded to the surface of the transition metal substrate (10) via chemical bonds.

9. A method for preparing a multi-level nanostructured anode material, characterized in that: include: Step 1: immersing a transition metal substrate (10) in a solution containing hydrogen phosphate ions and ammonium ions, and forming a nano-columnar array (20) containing transition metal phosphate on the transition metal substrate (10) through a hydrothermal reaction; Step 2: forming a nano-layered modification layer comprising aluminum ions and transition metal double hydroxide on the surface of the nano-columnar array (20) by electrodeposition; Step 3: soaking the transition metal substrate (10) having the nano-layered modified layer and the nano-columnar array (20) in a strong alkaline solution to remove the aluminum ions and construct cation vacancies.

10. Use of the multi-level nanostructured anode material according to any one of claims 1 to 8, characterized in that: Applied to the oxygen evolution reaction of catalyzing the electrolysis of water to produce hydrogen, the application also includes: The multi-level nanostructured anode material is used as an anode for catalytic electrolysis of water to produce hydrogen, and a positive electrode potential is applied to the anode to cause surface reconstruction of the nano-layered modified layer in the anode material to expose more active sites.

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