Nickel-cobalt alloy composite nickel-cobalt oxide material and preparation method and application thereof

Abstract

The invention discloses a nickel-cobalt alloy composite nickel-cobalt oxide material and a preparation method and application thereof. The invention particularly relates to the fields of nano materials and electro-catalysis. The preparation method comprises the following steps: mixing inorganic cobalt salt, inorganic nickel salt, terephthalic acid and an N, N-dimethylformamide aqueous solution to form a homogeneous solution; placing the homogeneous solution in a reaction kettle independently or together with a conductive substrate for solvothermal reaction, cooling to room temperature, collecting an in-situ self-growing material containing or not containing the conductive substrate, and washing and drying to obtain an in-situ self-growing nickel-doped terephthalic acid cobalt material precursor containing or not containing the conductive substrate; and finally, pyrolyzing, washing and drying the precursor at high temperature to obtain the in-situ self-growing nickel-cobalt alloy composite nickel-cobalt oxide material containing or not containing the conductive substrate. The nickel-cobalt alloy composite nickel-cobalt oxide material is excellent in performance, has good application prospects in the fields of electro-catalysis water decomposition and electro-catalysis heavy water decomposition, is simple in technological process and is suitable for large-scale industrial production.

Description

Technical Field

[0001] The present invention relates to the fields of nanomaterials and electrocatalysis, and in particular to a nickel-cobalt alloy composite nickel-cobalt oxide material, a preparation method thereof, and applications thereof. Background Art

[0002] Since the Industrial Revolution, the environmental problems and energy crises caused by the large-scale use of fossil fuels by humans have become increasingly serious, posing a serious threat to the sustainable development of society. To meet the above challenges, people have conducted comprehensive research on clean energy technologies. Among them, the hydrogen economy and deuterium economy, which are centered on hydrogen and deuterium, efficiently release the energy of hydrogen and deuterium through electrochemical and nuclear fusion reactions, respectively, thereby achieving a nearly unlimited supply of clean energy. In terms of raw material acquisition, electrolysis of water and electrolysis of heavy water are currently one of the main methods for preparing hydrogen and deuterium, but the process is mainly restricted by the high overpotential of the electrode reaction and the high price of commercial precious metal catalysts, and its production cost remains high. Based on the above reasons, in order to reduce the overall cost of electrolysis of water and electrolysis of heavy water and improve efficiency, we can start from the following two aspects: (1) reduce the reaction overpotential, including the overpotential of the cathode hydrogen evolution reaction and deuterium evolution reaction process; (2) design low-cost, high-stability catalysts to replace precious metal catalysts.

[0003] Compared with precious metal-based materials, transition metal-based materials (cobalt, nickel and iron, etc.) have become attractive alternative catalytic materials by virtue of their own catalytic activity for hydrogen evolution and deuterium evolution, and their abundant reserves in nature and relatively low prices. However, the electrocatalytic performance of single metal transition metal-based materials is still difficult to meet the requirements of industrial-scale applications. Therefore, it is necessary to improve its performance by means of element doping, structural regulation, interface optimization, etc., so as to meet the many requirements in large-scale production applications. In addition, compared with traditional powdered nanocatalysts, self-supporting electrodes using conductive substrates to support catalysts have more advantages in terms of active site density, electrical conductivity and high current resistance, and can better meet the needs of practical applications. For example, the Co-loaded nitrogen-doped carbon nanotube powder material prepared by solvent self-assembly and high-temperature calcination method in Chinese patent CN115896859A uses a metal catalyst powder prepared by cobalt salt, zinc salt and benzimidazole, although it has excellent electrocatalytic hydrogen evolution performance (current density reaches 10mA / cm 2When the potential is 147mV), although the patent does not add a carbon source, it uses zinc salts, which cannot prove the growth of the material on a conductive substrate. Its application in an industrial production environment with high current density has certain limitations. For example, Chinese patent CN109166733A is prepared by a hydrothermal method using metal nickel salts and / or metal cobalt salts, terephthalic acid, and N,N-dimethylformamide solvent. Although the patent also uses nickel salts and cobalt salts, it is necessary to add additional carbon sources such as graphene in the patent. The carbon source mainly increases the specific surface area and plays the role of support and conductive path. However, if no carbon source is added, it is easy to agglomerate and affect the electrochemical performance. Adding a carbon source will not only increase the production cost, but also make the reaction process more complicated and have poor repeatability. Moreover, the patent is mainly applicable to supercapacitor electrodes and cannot be used for electrocatalytic water / heavy water decomposition. Whether the direct use of metal catalyst powder can achieve in-situ growth on a conductive substrate is an uncertain factor. For example, Chinese patent CN114318404A utilizes nickel salt, terephthalic acid, NN-dimethylformamide, and Ni-loaded carbon paper. Although this patent does not require the addition of an additional carbon source, it requires electrodeposition and uses Ni-loaded carbon paper as a conductive substrate. This patent is suitable for the oxidation of 5-hydroxymethylfurfural and cannot be used for electrocatalytic water / heavy water decomposition.

[0004] Based on the above situation, designing transition metal-based electrocatalysts with scientific structure, excellent performance and controllable cost is very critical in the current field of electrolysis of water to produce hydrogen or electrolysis of heavy water to produce deuterium. Summary of the Invention

[0005] To this end, the present invention provides a nickel-cobalt alloy composite nickel-cobalt oxide material and a preparation method and application thereof to solve the problems of the prior art.

[0006] The present invention aims to provide a high-performance nickel-cobalt alloy composite nickel-cobalt oxide material constructed based on the dual strategies of element doping and morphology control for use in the electrocatalytic hydrogen evolution reaction at the cathode end of water decomposition and the deuterium evolution reaction at the cathode end of heavy water decomposition, and to provide a low-cost, safe and reliable preparation method that can be industrially produced on a large scale.

[0007] The present invention proposes to control the ratio of cobalt ions and nickel ions in an organic solution of a transition metal inorganic salt under the protection of an inert gas, and prepare a nickel-doped cobalt terephthalate precursor by a solvent thermal method, and then pyrolyze the above precursor at high temperature to obtain a nickel-cobalt alloy composite nickel-cobalt oxide ultra-thin nanosheet material.

[0008] In order to achieve the above object, the present invention provides the following technical solutions:

[0009] According to a first aspect of the present invention, a method for preparing a nickel-cobalt alloy composite nickel-cobalt oxide material is provided, the method comprising:

[0010] Step 1: Mixing an inorganic cobalt salt, an inorganic nickel salt, and terephthalic acid in a mixed solution of deionized water and N,N-dimethylformamide into which a protective gas is continuously introduced to form a homogeneous solution;

[0011] Step 2: placing the homogeneous solution obtained in step 1 in a reactor for solvothermal reaction, and collecting the solid powder after cooling to room temperature, washing, and drying the solid powder to obtain a nickel-doped cobalt terephthalate powder precursor;

[0012] Step three: pyrolyze the precursor obtained in step two at high temperature, wash and dry it, and finally obtain a nickel-cobalt alloy composite nickel-cobalt oxide powder material.

[0013] Furthermore, in step 1, the inorganic cobalt salt is one or more of cobalt chloride, cobalt nitrate, and cobalt sulfate; and the inorganic nickel salt is one or more of nickel chloride, nickel nitrate, and nickel sulfate.

[0014] Furthermore, in step 1, the molar ratio of the total amount of the inorganic cobalt salt and the inorganic nickel salt to terephthalic acid is 0.5-2:1; the molar ratio of the inorganic cobalt salt and the inorganic nickel salt is 6-1:1; and the molar ratio of deionized water to N,N-dimethylformamide is 1:1-4.

[0015] Furthermore, in step 1, the protective gas is nitrogen or argon.

[0016] Furthermore, in the step 2, the reaction temperature of the solvent thermal reaction is 100-140° C., and the reaction time is 10-30 hours.

[0017] Furthermore, in step three, the reaction temperature of the high-temperature pyrolysis is 250-350° C., and the reaction time is 2-4 hours.

[0018] Furthermore, in step three, the washing liquid is one or more of methanol, ethanol, water, acetone or isopropanol; and the drying is forced air drying, vacuum drying or freeze drying.

[0019] According to a second aspect of the present invention, a nickel-cobalt alloy composite nickel-cobalt oxide material prepared by the above method is provided. The material is a nanosheet composed of tightly connected nickel-cobalt alloy, nickel oxide and cobalt oxide.

[0020] According to the third aspect of the present invention, the nickel-cobalt alloy composite nickel-cobalt oxide material is used in an electrocatalyst, wherein the electrocatalyst is used in a hydrogen evolution reaction at a cathode end of water decomposition or a deuterium evolution reaction at a cathode end of heavy water decomposition.

[0021] As an electrocatalyst, a conductive substrate is required. The preparation method of adding a conductive substrate is as follows:

[0022] Step 1: Mixing an inorganic cobalt salt, an inorganic nickel salt, and terephthalic acid in a mixed solution of deionized water and N,N-dimethylformamide into which a protective gas is continuously introduced to form a homogeneous solution;

[0023] Step 2: placing the homogeneous solution obtained in step 1 and the conductive substrate in a reaction vessel for a solvothermal reaction, cooling to room temperature, collecting the solid powder, washing it, and drying it to obtain a nickel-doped cobalt terephthalate precursor grown in situ on the conductive substrate;

[0024] Step three, pyrolyzing the precursor obtained in step two at high temperature, washing and drying, and finally obtaining a nickel-cobalt alloy composite nickel-cobalt oxide material grown in situ on a conductive substrate.

[0025] Furthermore, the conductive substrate is nickel foam, cobalt foam, carbon cloth, carbon paper, nickel foil or cobalt foil.

[0026] Other preparation method parameters are the same as those of the preparation method of nickel-cobalt alloy composite nickel-cobalt oxide material.

[0027] The present invention has the following advantages:

[0028] The present invention successfully retains the nanosheet structure of a nickel-doped cobalt terephthalate precursor through high-temperature pyrolysis and obtains a nickel-cobalt alloy composite nickel-cobalt oxide with a stable structure; during the high-temperature pyrolysis process, the carbon source provided by the terephthalate ions reduces part of the metal cations to form a nickel-cobalt alloy element and low-valent nickel-cobalt oxide active sites. At the same time, during the pyrolysis process, the material maintains the precursor layered nanosheet structure with a large electrochemical active area; the nickel-cobalt alloy doping reduces the band gap of the nickel-cobalt oxide, thereby reducing the charge transfer resistance, improving the electron transfer efficiency, and enhancing the efficiency of the hydrogen evolution / deuterium reaction.

[0029] The experimental results of the present invention show that the nickel-cobalt alloy composite nickel-cobalt oxide material provided by the present invention is used as a catalyst for hydrogen evolution reaction at the cathode end of water electrolysis. 2 The required potential is only 1.25V (vs. RHE), which is 340mV lower than the potential of the anodic oxygen evolution reaction. At the same time, high value-added product formic acid is generated, and the highest Faraday efficiency is 91.5%. The nickel-cobalt alloy composite nickel-cobalt oxide material provided by the present invention is used as a catalyst in the cathode hydrogen evolution reaction of water electrolysis. When the overpotential is 64mV, its current density can reach 10mA / cm 2 In the deuterium evolution reaction at the cathode of heavy water electrolysis, the current density can reach 10 mA / cm when the overpotential is 111 mV. 2 , the catalyst can also be grown in situ on a conductive substrate to achieve better performance.

[0030] The material obtained by the present invention is a nickel-cobalt alloy composite nickel-cobalt oxide with an ultrathin nanosheet structure. Compared with other existing similar transition metal-based materials, it has a larger electrochemical specific surface area and a richer active site content, which helps to enhance the performance of the electrocatalytic water / heavy water electrolysis hydrogen / deuterium reaction. The nickel-cobalt alloy composite nickel-cobalt oxide material of the present invention has excellent performance and has good application prospects in the fields of electrocatalytic water decomposition and electrocatalytic heavy water decomposition. At the same time, the process flow is simple and is suitable for large-scale industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the embodiments or the description of the prior art. Obviously, the drawings described below are merely exemplary, and those skilled in the art can derive other implementation drawings based on the provided drawings without inventive effort.

[0032] The structures, proportions, sizes, etc. illustrated in this specification are intended only to complement the contents disclosed herein and to facilitate understanding and reading by persons familiar with the art. They are not intended to limit the conditions under which the present invention may be implemented and therefore have no substantive technical significance. Any structural modifications, changes in proportions, or adjustments in sizes, without affecting the efficacy and objectives of the present invention, shall still fall within the scope of the technical contents disclosed herein.

[0033] Figure 1 This is a scanning electron microscope photograph of a nickel-cobalt alloy composite nickel-cobalt oxide powder material provided in Example 1 of the present invention;

[0034] Figure 2 This is a high-magnification scanning electron microscope photograph of the nickel-cobalt alloy composite nickel-cobalt oxide powder material provided in Example 1 of the present invention;

[0035] Figure 3 This is the XRD curve of the nickel-cobalt alloy composite nickel-cobalt oxide powder material provided in Example 1 of the present invention;

[0036] Figure 4 Linear sweep voltammetry curves of the powder materials provided in Examples 1-10 of the present invention and Comparative Example 9 in the cathode hydrogen evolution reaction of water electrolysis;

[0037] Figure 5 Linear sweep voltammetry curves of the powder materials provided in Examples 1-10 and Comparative Example 9 of the present invention in the cathode deuterium evolution reaction in heavy water electrolysis;

[0038] Figure 6 Linear sweep voltammetry curves of the powder materials provided in Example 1 and Comparative Examples 1-9 of the present invention in the cathode hydrogen evolution reaction of water electrolysis;

[0039] Figure 7 Linear sweep voltammetry curves of the powder materials provided in Example 1 and Comparative Examples 1-9 of the present invention in the cathode deuterium evolution reaction in heavy water electrolysis;

[0040] Figure 8 Linear sweep voltammetry curves of the conductive substrate materials provided in Examples 1-10 of the present invention and Comparative Example 9 in the cathode hydrogen evolution reaction of water electrolysis;

[0041] Figure 9 Linear sweep voltammetry curves of the conductive substrate materials provided in Examples 1-10 of the present invention and Comparative Example 9 in the cathode deuterium evolution reaction in heavy water electrolysis;

[0042] Figure 10 Linear sweep voltammetry curves of the conductive substrate material provided in Example 1 and Comparative Examples 1-9 of the present invention in the cathode hydrogen evolution reaction of water electrolysis;

[0043] Figure 11 Linear sweep voltammetry measurement curves of the conductive substrate materials provided in Example 1 and Comparative Examples 1-9 of the present invention in the cathode deuterium evolution reaction in heavy water electrolysis. DETAILED DESCRIPTION

[0044] The following describes the implementation of the present invention using specific embodiments. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. Obviously, the embodiments described are only a portion of the present invention, not all of it. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are intended to fall within the scope of protection of the present invention.

[0045] Example 1

[0046] This embodiment provides a method for preparing a nickel-cobalt alloy composite nickel-cobalt oxide material:

[0047] (1) 1.785 g of cobalt chloride hexahydrate (7.5 mmol), 0.714 g of nickel chloride hexahydrate (3.0 mmol), and 1.740 g of terephthalic acid (10.5 mmol) were dissolved in a mixed solution of 100 ml of deionized water and 300 ml of N,N-dimethylformamide, into which nitrogen was continuously bubbled, to form a homogeneous solution;

[0048] (2) The above solution was placed in a 500 ml Teflon-lined autoclave, and the temperature was raised to 120°C at a rate of 5°C / min and maintained for 20 hours for a solvothermal reaction. After the reaction was completed and cooled to room temperature, the solid material was collected, washed three times with ethanol, and then vacuum dried to obtain nickel-doped cobalt terephthalate precursor powder;

[0049] (3) The precursor powder obtained in step (2) was placed in a tube furnace, and the temperature was raised to 300°C at a rate of 5°C / min and maintained for 3 hours. After the high-temperature calcination, the precursor powder was washed with ethanol and vacuum-dried to obtain a nickel-cobalt alloy composite nickel-cobalt oxide powder material (NiCo-NiO-CoO-1).

[0050] The scanning electron microscope photo of the obtained nickel-cobalt alloy composite nickel-cobalt oxide powder material is as follows: Figure 1 As shown; high magnification scanning electron microscope photos as shown Figure 2 As shown, XRD Figure 3 As shown. Figure 1 It can be seen that the nickel-cobalt alloy composite nickel-cobalt oxide powder material prepared by solvent thermal and high-temperature calcination in this embodiment presents a three-dimensional morphology of ultra-thin nanosheet aggregation. Figure 2 High-magnification scanning electron microscopy shows that Figure 1 Small nanosheets grow on the large nanosheets in the sample, with a spacing of about 100-400nm, which helps to increase the specific surface area of ​​the nickel-cobalt alloy composite nickel-cobalt oxide material. Figure 3 As shown, the nickel-cobalt alloy composite nickel-cobalt oxide powder material obtained in this embodiment shows multiple diffraction peaks. By comparing the positions of these peaks with the diffraction peak positions in the standard card, it can be determined that nickel-cobalt elements and nickel-cobalt oxides are present in the sample, indicating the successful synthesis of the nickel-cobalt alloy composite nickel-cobalt oxide material.

[0051] Preparation method of nickel-cobalt alloy composite nickel-cobalt oxide catalyst with conductive substrate:

[0052] Except for step (2): a piece of nickel foam with a size of 6 cm × 10 cm was added to the solution obtained in step (1), the other parameters and steps were exactly the same as the above steps, and finally a nickel-cobalt alloy composite nickel-cobalt oxide material (NiCo-NiO-CoO / NF-1) in situ grown on the surface of nickel foam was obtained, with a loading of 64.31 mg / cm 2 .

[0053] Example 2

[0054] This embodiment provides a method for preparing a nickel-cobalt alloy composite nickel-cobalt oxide material:

[0055] (1) 2.142 g of cobalt chloride hexahydrate (9.0 mmol), 0.357 g of nickel chloride hexahydrate (1.5 mmol), and 3.480 g of terephthalic acid (21 mmol) were dissolved in a mixed solution of 100 ml of deionized water and 300 ml of N,N-dimethylformamide, into which argon was continuously introduced, to form a homogeneous solution;

[0056] (2) The above solution was placed in a 500 ml Teflon-lined autoclave, and the temperature was raised to 120°C at a rate of 5°C / min and maintained for 20 hours for a solvothermal reaction. After the reaction was completed and cooled to room temperature, the solid material was collected, washed three times with ethanol, and then vacuum dried to obtain nickel-doped cobalt terephthalate precursor powder;

[0057] (3) The precursor powder obtained in step (2) was placed in a tube furnace, and the temperature was raised to 300°C at a rate of 5°C / min and maintained for 3 hours. After the high-temperature calcination, it was washed with ethanol and vacuum-dried to obtain a nickel-cobalt alloy composite nickel-cobalt oxide powder material (NiCo-NiO-CoO-2).

[0058] Preparation method of nickel-cobalt alloy composite nickel-cobalt oxide catalyst with conductive substrate:

[0059] Except for step (2): a piece of nickel foam with a size of 6 cm × 10 cm was added to the solution obtained in step (1), the other parameters and steps were exactly the same as the above steps, and finally a nickel-cobalt alloy composite nickel-cobalt oxide material (NiCo-NiO-CoO / NF-2) in situ grown on the surface of nickel foam was obtained, with a loading of 62.83 mg / cm 2 .

[0060] Example 3

[0061] This embodiment provides a method for preparing a nickel-cobalt alloy composite nickel-cobalt oxide material:

[0062] (1) 1.250 g of cobalt chloride hexahydrate (5.25 mmol), 1.250 g of nickel chloride hexahydrate (5.25 mmol), and 0.870 g of terephthalic acid (5.25 mmol) were dissolved in a mixed solution of 80 ml of deionized water and 320 ml of N,N-dimethylformamide, into which nitrogen was continuously bubbled, to form a homogeneous solution;

[0063] (2) The above solution was placed in a 500 ml Teflon-lined autoclave, and the temperature was raised to 120°C at a rate of 5°C / min and maintained for 20 hours for a solvothermal reaction. After the reaction was completed and cooled to room temperature, the solid material was collected, washed three times with ethanol, and dried by air blast to obtain nickel-doped cobalt terephthalate precursor powder.

[0064] (3) The precursor powder obtained in step (2) is placed in a tube furnace, heated to 300°C at a rate of 5°C / min and maintained for 3 hours. After high-temperature calcination, it is washed with ethanol and dried with air to obtain a nickel-cobalt alloy composite nickel-cobalt oxide powder material (NiCo-NiO-CoO-3).

[0065] Preparation method of nickel-cobalt alloy composite nickel-cobalt oxide catalyst with conductive substrate:

[0066] Except for step (2): a piece of nickel foam with a size of 6 cm × 10 cm was added to the solution obtained in step (1), the other parameters and steps were exactly the same as the above steps, and finally a nickel-cobalt alloy composite nickel-cobalt oxide material (NiCo-NiO-CoO / NF-3) in situ grown on the surface of nickel foam was obtained, with a loading of 61.09 mg / cm 2 .

[0067] Example 4

[0068] This embodiment provides a method for preparing a nickel-cobalt alloy composite nickel-cobalt oxide material:

[0069] (1) 1.785 g of cobalt chloride hexahydrate (7.5 mmol), 0.714 g of nickel chloride hexahydrate (3.0 mmol), and 1.740 g of terephthalic acid (10.5 mmol) were dissolved in a mixed solution of 200 ml of deionized water and 200 ml of N,N-dimethylformamide, which was continuously purged with nitrogen, to form a homogeneous solution;

[0070] (2) The above solution was placed in a 500 ml Teflon-lined autoclave, and the temperature was raised to 120°C at a rate of 5°C / min and maintained for 20 hours for a solvothermal reaction. After the reaction was completed and cooled to room temperature, the solid material was collected, washed three times with methanol, and freeze-dried to obtain nickel-doped cobalt terephthalate precursor powder;

[0071] (3) The precursor powder obtained in step (2) was placed in a tube furnace, and the temperature was raised to 300° C. at a rate of 5° C. / min and maintained for 3 hours. After the high-temperature calcination, the precursor powder was washed with methanol and freeze-dried to obtain a nickel-cobalt alloy composite nickel-cobalt oxide powder material (NiCo-NiO-CoO-4).

[0072] Preparation method of nickel-cobalt alloy composite nickel-cobalt oxide catalyst with conductive substrate:

[0073] Except for step (2): a piece of nickel foam with a size of 6 cm × 10 cm was added to the solution obtained in step (1), the other parameters and steps were exactly the same as the above steps, and finally a nickel-cobalt alloy composite nickel-cobalt oxide material (NiCo-NiO-CoO / NF-4) in situ grown on the surface of nickel foam was obtained, with a loading of 65.56 mg / cm 2 .

[0074] Example 5

[0075] This embodiment provides a method for preparing a nickel-cobalt alloy composite nickel-cobalt oxide material:

[0076] (1) 1.785 g of cobalt chloride hexahydrate (7.5 mmol), 0.873 g of nickel nitrate hexahydrate (3.0 mmol), and 1.740 g of terephthalic acid (10.5 mmol) were dissolved in a mixed solution of 100 ml of deionized water and 300 ml of N,N-dimethylformamide, which was continuously purged with nitrogen, to form a homogeneous solution;

[0077] (2) The above solution was placed in a 500 ml Teflon-lined autoclave, and the temperature was raised to 140°C at a rate of 5°C / min and maintained for 20 hours for a solvothermal reaction. After the reaction was completed and cooled to room temperature, the solid material was collected, washed three times with deionized water, and then vacuum dried to obtain nickel-doped cobalt terephthalate precursor powder;

[0078] (3) The precursor powder obtained in step (2) was placed in a tube furnace, and the temperature was raised to 300° C. at a rate of 5° C. / min and maintained for 3 hours. After the high-temperature calcination, it was washed with deionized water and vacuum-dried to obtain a nickel-cobalt alloy composite nickel-cobalt oxide powder material (NiCo-NiO-CoO-5).

[0079] Preparation method of nickel-cobalt alloy composite nickel-cobalt oxide catalyst with conductive substrate:

[0080] Except for step (2): a piece of nickel foam with a size of 6 cm × 10 cm was added to the solution obtained in step (1), the other parameters and steps were exactly the same as the above steps, and finally a nickel-cobalt alloy composite nickel-cobalt oxide material (NiCo-NiO-CoO / NF-5) in situ grown on the surface of nickel foam was obtained, with a loading of 64.32 mg / cm 2 .

[0081] Example 6

[0082] This embodiment provides a method for preparing a nickel-cobalt alloy composite nickel-cobalt oxide material:

[0083] (1) 1.785 g of cobalt chloride hexahydrate (7.5 mmol), 0.714 g of nickel chloride hexahydrate (3.0 mmol), and 1.740 g of terephthalic acid (10.5 mmol) were dissolved in a mixed solution of 100 ml of deionized water and 300 ml of N,N-dimethylformamide, which was continuously purged with nitrogen, to form a homogeneous solution;

[0084] (2) The above solution was placed in a 500 ml Teflon-lined autoclave, and the temperature was raised to 100°C at a rate of 5°C / min and maintained for 20 hours for a solvothermal reaction. After the reaction was completed and cooled to room temperature, the solid material was collected, washed with acetone three times, and vacuum dried to obtain nickel-doped cobalt terephthalate precursor powder.

[0085] (3) The precursor powder obtained in step (2) was placed in a tube furnace, and the temperature was raised to 300° C. at a rate of 5° C. / min and maintained for 3 hours. After the high-temperature calcination, the precursor powder was washed with acetone and vacuum-dried to obtain a nickel-cobalt alloy composite nickel-cobalt oxide powder material (NiCo-NiO-CoO-6).

[0086] Preparation method of nickel-cobalt alloy composite nickel-cobalt oxide catalyst with conductive substrate:

[0087] Except for step (2): a piece of nickel foam with a size of 6 cm × 10 cm was added to the solution obtained in step (1), the other parameters and steps were exactly the same as the above steps, and finally a nickel-cobalt alloy composite nickel-cobalt oxide material (NiCo-NiO-CoO / NF-6) in situ grown on the surface of nickel foam was obtained, with a loading of 67.83 mg / cm 2 .

[0088] Example 7

[0089] This embodiment provides a method for preparing a nickel-cobalt alloy composite nickel-cobalt oxide material:

[0090] (1) 1.785 g of cobalt chloride hexahydrate (7.5 mmol), 0.714 g of nickel chloride hexahydrate (3.0 mmol), and 1.740 g of terephthalic acid (10.5 mmol) were dissolved in a mixed solution of 100 ml of deionized water and 300 ml of N,N-dimethylformamide, which was continuously purged with nitrogen, to form a homogeneous solution;

[0091] (2) The above solution was placed in a 500 ml Teflon-lined autoclave, and the temperature was raised to 120°C at a rate of 5°C / min and maintained for 10 hours for a solvothermal reaction. After the reaction was completed and cooled to room temperature, the solid material was collected, washed three times with isopropanol, and then vacuum-dried to obtain nickel-doped cobalt terephthalate precursor powder;

[0092] (3) The precursor powder obtained in step (2) was placed in a tube furnace, and the temperature was raised to 300°C at a rate of 5°C / min and maintained for 3 hours. After the high-temperature calcination, the powder was washed with isopropyl alcohol and vacuum dried to obtain a nickel-cobalt alloy composite nickel-cobalt oxide powder material (NiCo-NiO-CoO-7).

[0093] Preparation method of nickel-cobalt alloy composite nickel-cobalt oxide catalyst with conductive substrate:

[0094] Except for step (2): a cobalt foil of 6 cm × 10 cm in size was added to the solution obtained in step (1), the other parameters and steps were exactly the same as the above steps, and finally a nickel-cobalt alloy composite nickel-cobalt oxide material (NiCo-NiO-CoO / NF-7) in situ grown on the surface of nickel foam was obtained, with a loading of 66.21 mg / cm 2 .

[0095] Example 8

[0096] This embodiment provides a method for preparing a nickel-cobalt alloy composite nickel-cobalt oxide material:

[0097] (1) 2.182 g of cobalt nitrate hexahydrate (7.5 mmol), 0.714 g of nickel chloride hexahydrate (3.0 mmol), and 1.740 g of terephthalic acid (10.5 mmol) were dissolved in a mixed solution of 100 ml of deionized water and 300 ml of N,N-dimethylformamide, which was continuously purged with nitrogen, to form a homogeneous solution;

[0098] (2) The above solution was placed in a 500 ml Teflon-lined autoclave, and the temperature was raised to 120°C at a rate of 5°C / min and maintained for 30 hours for a solvothermal reaction. After the reaction was completed and cooled to room temperature, the solid material was collected, washed three times with ethanol, and then vacuum dried to obtain nickel-doped cobalt terephthalate precursor powder;

[0099] (3) The precursor powder obtained in step (2) was placed in a tube furnace, and the temperature was raised to 300°C at a rate of 5°C / min and maintained for 3 hours. After the high-temperature calcination, it was washed with ethanol and vacuum-dried to obtain a nickel-cobalt alloy composite nickel-cobalt oxide powder material (NiCo-NiO-CoO-8).

[0100] Preparation method of nickel-cobalt alloy composite nickel-cobalt oxide catalyst with conductive substrate:

[0101] Except for step (2): a nickel foil of size 6 cm × 10 cm was added to the solution obtained in step (1), the other parameters and steps were exactly the same as the above steps, and finally a nickel-cobalt alloy composite nickel-cobalt oxide material (NiCo-NiO-CoO / NF-8) in situ grown on the surface of the nickel foil was obtained, with a loading of 61.56 mg / cm 2 .

[0102] Example 9

[0103] This embodiment provides a method for preparing a nickel-cobalt alloy composite nickel-cobalt oxide material:

[0104] (1) 2.108 g of cobalt sulfate hexahydrate (7.5 mmol), 0.714 g of nickel chloride hexahydrate (3.0 mmol), and 1.740 g of terephthalic acid (10.5 mmol) were dissolved in a mixed solution of 100 ml of deionized water and 300 ml of N,N-dimethylformamide, which was continuously purged with nitrogen, to form a homogeneous solution;

[0105] (2) The above solution was placed in a 500 ml Teflon-lined autoclave, and the temperature was raised to 120°C at a rate of 5°C / min and maintained for 20 hours for a solvothermal reaction. After the reaction was completed and cooled to room temperature, the solid material was collected, washed three times with ethanol, and then vacuum dried to obtain nickel-doped cobalt terephthalate precursor powder;

[0106] (3) The precursor powder obtained in step (2) was placed in a tube furnace, and the temperature was raised to 250°C at a rate of 5°C / min and maintained for 4 hours. After the high-temperature calcination, it was washed with ethanol and vacuum-dried to obtain a nickel-cobalt alloy composite nickel-cobalt oxide powder material (NiCo-NiO-CoO-9).

[0107] Preparation method of nickel-cobalt alloy composite nickel-cobalt oxide catalyst with conductive substrate:

[0108] Except for step (2): a piece of cobalt foam with a size of 6 cm × 10 cm was added to the solution obtained in step (1), the other parameters and steps were exactly the same as the above steps, and finally a nickel-cobalt alloy composite nickel-cobalt oxide material (NiCo-NiO-CoO / CF-9) in situ grown on the surface of cobalt foam was obtained, with a loading of 67.91 mg / cm 2 .

[0109] Example 10

[0110] This embodiment provides a method for preparing a nickel-cobalt alloy composite nickel-cobalt oxide material:

[0111] (1) 1.785 g of cobalt chloride hexahydrate (7.5 mmol), 0.843 g of nickel sulfate hexahydrate (3.0 mmol), and 1.740 g of terephthalic acid (10.5 mmol) were dissolved in a mixed solution of 100 ml of deionized water and 300 ml of N,N-dimethylformamide, which was continuously purged with nitrogen, to form a homogeneous solution;

[0112] (2) The above solution was placed in a 500 ml Teflon-lined autoclave, and the temperature was raised to 120°C at a rate of 5°C / min and maintained for 20 hours for a solvothermal reaction. After the reaction was completed and cooled to room temperature, the solid material was collected, washed three times with ethanol, and then vacuum dried to obtain nickel-doped cobalt terephthalate precursor powder;

[0113] (3) The precursor powder obtained in step (2) was placed in a tube furnace, and the temperature was raised to 350° C. at a heating rate of 5° C. / min and maintained for 2 hours. After the high-temperature calcination, the precursor powder was washed with ethanol and vacuum-dried to obtain a nickel-cobalt alloy composite nickel-cobalt oxide powder material (NiCo-NiO-CoO-10).

[0114] Preparation method of nickel-cobalt alloy composite nickel-cobalt oxide catalyst with conductive substrate:

[0115] Except for step (2): a piece of carbon paper with a size of 6 cm × 10 cm was added to the solution obtained in step (1), the other parameters and steps were exactly the same as the above steps, and finally a nickel-cobalt alloy composite nickel-cobalt oxide material (NiCo-NiO-CoO / CC-10) in situ grown on the carbon paper surface was obtained, with a loading of 60.98 mg / cm 2 .

[0116] Comparative Example 1

[0117] This comparative example provides a method for preparing a cobalt-based composite cobalt oxide (Co-CoO) material:

[0118] (1) 2.499 g of cobalt chloride hexahydrate (10.5 mmol) and 1.740 g of terephthalic acid (10.5 mmol) were dissolved in a mixed solution of 100 ml of deionized water and 300 ml of N,N-dimethylformamide, into which nitrogen was continuously bubbled, to form a homogeneous solution;

[0119] (2) The above solution was placed in a 500 ml Teflon-lined autoclave, and the temperature was raised to 120°C at a rate of 5°C / min and maintained for 20 hours for a solvothermal reaction. After the reaction was completed and cooled to room temperature, the solid material was collected, washed three times with ethanol, and vacuum dried to obtain a cobalt terephthalate precursor powder.

[0120] (3) The precursor powder obtained in step (2) was placed in a tube furnace, and the temperature was raised to 300°C at a rate of 5°C / min and maintained for 3 hours. After the high-temperature calcination, it was washed with ethanol and vacuum-dried to obtain a cobalt-containing composite cobalt oxide powder material (Co-CoO).

[0121] Preparation method of cobalt oxide composite catalyst with conductive substrate added:

[0122] Except for step (2): a piece of cobalt foam with a size of 6 cm × 10 cm was added to the solution obtained in step (1), the other parameters and steps were exactly the same as the above steps, and finally a cobalt element composite cobalt oxide material (Co-CoO / CF) in situ grown on the surface of the cobalt foam was obtained, with a loading of 66.13 mg / cm 2 .

[0123] Comparative Example 2

[0124] This comparative example provides a method for preparing a nickel-based composite nickel oxide Ni-NiO material:

[0125] (1) 2.499 g of nickel chloride hexahydrate (10.5 mmol) and 1.740 g of terephthalic acid (10.5 mmol) were dissolved in a mixed solution of 100 ml of deionized water and 300 ml of N,N-dimethylformamide, into which nitrogen was continuously bubbled, to form a homogeneous solution;

[0126] (2) The above solution was placed in a 500 ml Teflon-lined autoclave, and the temperature was raised to 120°C at a rate of 5°C / min and maintained for 20 hours for a solvothermal reaction. After the reaction was completed and cooled to room temperature, the solid material was collected, washed three times with ethanol, and vacuum dried to obtain nickel terephthalate precursor powder.

[0127] (3) The precursor powder obtained in step (2) was placed in a tube furnace, heated to 300°C at a rate of 5°C / min and maintained for 3 hours. After high-temperature calcination, it was washed with ethanol and vacuum-dried to obtain a nickel-based composite nickel oxide powder material (Ni-NiO).

[0128] Preparation method of nickel-based composite nickel oxide catalyst with conductive substrate:

[0129] Except for step (2): a piece of nickel foam with a size of 6 cm × 10 cm was added to the solution obtained in step (1), the other parameters and steps were exactly the same as the above steps, and finally a nickel single substance composite nickel oxide material (Ni-NiO / NF) in situ grown on the surface of nickel foam was obtained, with a loading of 65.22 mg / cm 2 .

[0130] Comparative Example 3

[0131] This comparative example provides a method for preparing a nickel-doped cobalt terephthalate material (a metal organic framework of Ni and Co):

[0132] (1) 1.785 g of cobalt chloride hexahydrate (7.5 mmol), 0.714 g of nickel chloride hexahydrate (3.0 mmol), and 1.740 g of terephthalic acid (10.5 mmol) were dissolved in a mixed solution of 100 ml of deionized water and 300 ml of N,N-dimethylformamide, into which nitrogen was continuously bubbled, to form a homogeneous solution;

[0133] (2) The above solution was placed in a 500 ml Teflon-lined autoclave and heated to 120°C at a rate of 5°C / min and maintained for 20 hours for a solvothermal reaction. After the reaction was completed and cooled to room temperature, the solid material was collected, washed three times with ethanol, and vacuum dried to obtain nickel-doped cobalt terephthalate powder (NiCoBDC).

[0134] Preparation method of nickel-doped cobalt terephthalate catalyst with conductive substrate:

[0135] Except for step (2): a piece of nickel foam with a size of 6 cm × 10 cm was added to the solution obtained in step (1), the other parameters and steps were exactly the same as the above steps, and finally a nickel-doped cobalt terephthalate material (NiCoBDC / NF) in situ grown on the surface of nickel foam was obtained, with a loading of 67.61 mg / cm 2 .

[0136] Comparative Example 4

[0137] This comparative example provides a method for preparing a cobalt terephthalate material (Co metal organic framework):

[0138] (1) 2.499 g of cobalt chloride hexahydrate (10.5 mmol) and 1.740 g of terephthalic acid (10.5 mmol) were dissolved in a mixed solution of 100 ml of deionized water and 300 ml of N,N-dimethylformamide, into which nitrogen was continuously bubbled, to form a homogeneous solution;

[0139] (2) The above solution was placed in a 500 ml Teflon-lined autoclave and heated to 120°C at a rate of 5°C / min and maintained for 20 hours for a solvothermal reaction. After the reaction was completed and cooled to room temperature, the solid material was collected, washed three times with ethanol, and vacuum dried to obtain cobalt terephthalate powder (CoBDC).

[0140] Preparation method of cobalt terephthalate catalyst with conductive substrate:

[0141] Except for step (2): a piece of cobalt foam with a size of 6 cm × 10 cm was added to the solution obtained in step (1), the other parameters and steps were exactly the same as the above steps, and finally the cobalt terephthalate material (CoBDC / CF) grown in situ on the surface of the cobalt foam was obtained, with a loading of 66.22 mg / cm 2 .

[0142] Comparative Example 5

[0143] This comparative example provides a method for preparing a nickel terephthalate material (Ni metal organic framework):

[0144] (1) 2.499 g of nickel chloride hexahydrate (10.5 mmol) and 1.740 g of terephthalic acid (10.5 mmol) were dissolved in a mixed solution of 100 ml of deionized water and 300 ml of N,N-dimethylformamide, into which nitrogen was continuously bubbled, to form a homogeneous solution;

[0145] (2) The above solution was placed in a 500 ml Teflon-lined autoclave and heated to 120°C at a rate of 5°C / min and maintained for 20 hours for a solvothermal reaction. After the reaction was completed and cooled to room temperature, the solid material was collected, washed three times with ethanol, and vacuum dried to obtain nickel terephthalate powder (NiBDC).

[0146] Preparation method of nickel terephthalate material with conductive substrate added:

[0147] Except for step (2): a piece of nickel foam with a size of 6 cm × 10 cm was added to the solution obtained in step (1), the other parameters and steps were exactly the same as the above steps, and finally the nickel terephthalate material (NiBDC / NF) in situ grown on the surface of cobalt foam was obtained, with a loading of 63.96 mg / cm 2 .

[0148] Comparative Example 6

[0149] This comparative example provides a method for preparing a nickel-cobalt alloy composite nickel-cobalt oxide material:

[0150] (1) 1.785 g of cobalt chloride hexahydrate (7.5 mmol), 0.714 g of nickel chloride hexahydrate (3.0 mmol), and 1.239 g of benzimidazole (10.5 mmol) were dissolved in a mixed solution of 100 ml of deionized water and 300 ml of N,N-dimethylformamide, which was continuously purged with nitrogen, to form a homogeneous solution;

[0151] (2) The above solution was placed in a 500 ml Teflon-lined autoclave, and the temperature was raised to 120°C at a rate of 5°C / min and maintained for 20 hours for a solvothermal reaction. After the reaction was completed and cooled to room temperature, the solid material was collected, washed three times with ethanol, and then vacuum dried to obtain nickel-doped cobalt terephthalate precursor powder;

[0152] (3) The precursor powder obtained in step (2) was placed in a tube furnace, and the temperature was raised to 300°C at a rate of 5°C / min and maintained for 3 hours. After the high-temperature calcination, the powder was washed with ethanol and vacuum-dried to obtain a nickel-cobalt alloy composite nickel-cobalt oxide powder material (NiCo-NiO-CoO-BZ).

[0153] Preparation method of nickel-cobalt alloy composite nickel-cobalt oxide material with conductive substrate:

[0154] Except for step (2): a piece of nickel foam with a size of 6 cm × 10 cm was added to the solution obtained in step (1), the other parameters and steps were exactly the same as the above steps, and finally a nickel-cobalt alloy composite nickel-cobalt oxide powder material (NiCo-NiO-CoO-BZ / NF) in situ grown on the surface of nickel foam was obtained, with a loading of 63.32 mg / cm 2 .

[0155] Comparative Example 7

[0156] This comparative example provides a method for preparing a zinc-cobalt alloy composite zinc-cobalt oxide material:

[0157] (1) 1.785 g of cobalt chloride hexahydrate (7.5 mmol), 0.891 g of zinc nitrate hexahydrate (3.0 mmol), and 1.740 g of terephthalic acid (10.5 mmol) were dissolved in a mixed solution of 100 ml of deionized water and 300 ml of N,N-dimethylformamide, which was continuously purged with nitrogen, to form a homogeneous solution;

[0158] (2) The above solution was placed in a 500 ml Teflon-lined autoclave, and the temperature was raised to 120°C at a rate of 5°C / min and maintained for 20 hours for a solvothermal reaction. After the reaction was completed and cooled to room temperature, the solid material was collected, washed three times with ethanol, and vacuum dried to obtain a zinc-doped cobalt terephthalate precursor powder.

[0159] (3) The precursor powder obtained in step (2) was placed in a tube furnace, and the temperature was raised to 300°C at a rate of 5°C / min and maintained for 3 hours. After the high-temperature calcination, it was washed with ethanol and vacuum-dried to obtain a zinc-cobalt alloy composite zinc-cobalt oxide powder material (ZnCo-ZnO-CoO).

[0160] Preparation method of zinc-cobalt alloy composite zinc-cobalt oxide material with conductive substrate:

[0161] Except for step (2): a piece of nickel foam with a size of 6 cm × 10 cm was added to the solution obtained in step (1), the other parameters and steps were exactly the same as the above steps, and finally a zinc-cobalt alloy composite zinc-cobalt oxide powder material (ZnCo-ZnO-CoO / NF) in situ grown on the surface of nickel foam was obtained, with a loading of 68.14 mg / cm 2 .

[0162] Comparative Example 8

[0163] This comparative example relates to the preparation of a cobalt-loaded nitrogen-doped carbon nanotube composite material, and the specific operations are as follows:

[0164] (1) Zn 0.33 Co 0.67 -Synthesis of MOF crystals

[0165] 1.33 mmol of cobalt nitrate hexahydrate, 0.67 mmol of zinc nitrate hexahydrate, and 2 mmol of benzimidazole were added to 15 mL of a mixed solvent (DMF and H₂O in a 1:1 volume ratio). After thorough stirring, the resulting suspension was transferred to a polytetrafluoroethylene autoclave and heated to 140°C in a programmable temperature-controlled oven at 5°C / min. This temperature was maintained for 2 days, followed by slow cooling to room temperature at 5°C / h. Light purple, square single crystals were collected. After filtering the mother liquor, the crystals were washed several times with anhydrous ethanol and air-dried for 3 hours to enrich the sample. Finally, the powder was dried at 80°C.

[0166] (2) Preparation of ZnCo-NCNT composite materials

[0167] The synthesized ZnCo-MOF precursor sample was transferred to a corundum ark, and then transferred to a program-controlled tube furnace, placed horizontally in the center of the tube furnace, and heated to 1000°C at a heating rate of 5°C / min under the protection of N2 gas flow. The calcination was continued for 3 hours. After the tube furnace was naturally cooled, a black powder material ZnCo-NCNT composite material (ZnCo-NCNT) was obtained.

[0168] Preparation method of cobalt-loaded nitrogen-doped carbon nanotube material added to a conductive substrate:

[0169] 70 mg of ZnCo-NCNT was dispersed in 1 mL of a mixture of (100 μL Nafion and 900 μL CH 3 CH 2 OH) and sonicated for at least 30 min to form a uniform black slurry, which was then dropped onto a carbon cloth (ZnCo-NCNT / CC) with a size of 6 cm × 10 cm.

[0170] Comparative Example 9

[0171] Commercial catalyst PtC (10 wt%), manufacturer Shanghai Xinbo Chemical Technology Co., Ltd., product number LB857378.

[0172] Preparation method of PtC (10 wt%) material with conductive substrate:

[0173] 70 mg of PtC (10 wt %) was dispersed in 1 mL of a mixture of (100 μL Nafion and 900 μL CH 3 CH 2 OH) and sonicated for at least 30 min to form a uniform black slurry, which was then dropped onto a carbon cloth with a size of 6 cm × 10 cm (PtC (10 wt %) / CC).

[0174] The powder materials of Examples 1-10 and Comparative Examples 1-9 were used as electrocatalysts to test their electrocatalytic performance in the cathode hydrogen evolution reaction of electrolysis of water and the cathode deuterium evolution reaction of electrolysis of heavy water. Figure 4 As shown in the figure, the nickel-cobalt alloy composite nickel-cobalt oxide powder material exhibits superior performance, among which NiCo-NiO-CoO-1 has the best catalytic performance, with a current density of 10 mA / cm at an overpotential of 64 mV vs. RHE. 2 , compared with the existing commonly used PtC (10wt%) precious metal-based catalyst with a platinum mass fraction of 10% (overpotential of 63mV vs. RHE and current density of 10mA / cm 2 ) is equivalent. In terms of deuterium deposition at the cathode of heavy water electrolysis, Figure 5 As shown in Figure 2, the nickel-cobalt alloy composite nickel-cobalt oxide powder material exhibits excellent performance, among which NiCo-NiO-CoO-1 is the most outstanding, especially when the overpotential is 111mV vs.RHE, its current density can reach 10mA / cm 2 , compared with the existing commonly used PtC (10wt%) precious metal-based catalyst with a platinum mass fraction of 10% (overpotential of 111mV vs. RHE and current density of 10mA / cm 2 ) is equivalent. Figure 6 and Figure 7 As shown, NiCo-NiO-CoO-1 exhibits superior performance in water / heavy water electrolysis for hydrogen / deuterium evolution compared to single metal elements and oxide composites (Ni-NiO and Co-CoO), demonstrating a synergistic effect between nickel and cobalt bimetallics in water / heavy water electrolysis. Furthermore, NiCo-NiO-CoO-1 also exhibits superior performance in water / heavy water electrolysis for hydrogen / deuterium evolution compared to metal-organic framework precursors (NiCoBDC, CoBDC, and NiBDC), suggesting that nickel / cobalt-based metal-organic frameworks are not ideal for water / heavy water electrolysis. Finally, NiCo-NiO-CoO-1 was compared with NiCo-NiO-CoO-Bz (with organic ligand substitution), ZnCo-ZnO-CoO (with metal cation substitution), and ZnCo-NCNT (cobalt single-atom nitrogen-doped carbon material), revealing that NiCo-NiO-CoO-1 exhibits the best performance in water / heavy water electrolysis for hydrogen / deuterium evolution.

[0175] The nickel-cobalt alloy composite nickel-cobalt oxide material prepared in situ on a nickel foam conductive substrate as prepared in Examples 1-10 and Comparative Examples 1-9 was used as an electrocatalyst to test its electrocatalytic performance in the cathode hydrogen evolution reaction of water electrolysis and the cathode deuterium evolution reaction of heavy water electrolysis. Figure 8It can be seen that the nickel-cobalt alloy composite nickel-cobalt oxide material grown in situ on nickel foam exhibits excellent hydrogen evolution catalytic performance, among which NiCo-NiO-CoO / NF-1 has the best catalytic performance. At overpotentials of 219 and 264 mV, the cathode hydrogen evolution current density of water electrolysis can reach 100 and 250 mA / cm, respectively. 2 .from Figure 9 It can be seen that the nickel-cobalt alloy composite nickel-cobalt oxide material grown in situ on nickel foam exhibits excellent deuterium evolution catalytic performance, among which NiCo-NiO-CoO / NF-1 has the best catalytic performance. At overpotentials of 253 and 300 mV, the cathode deuterium evolution current density in heavy water electrolysis can reach 100 and 250 mA / cm, respectively. 2 .like Figure 10 and Figure 11 As shown, NiCo-NiO-CoO / NF-1 has better performance in water / heavy water electrolysis and hydrogen / deuterium evolution than single metal elements and oxide composites (Ni-NiO / NF and Co-CoO / CF), indicating that the synergistic effect of nickel and cobalt bimetallics in water / heavy water electrolysis is not eliminated by the presence of a conductive substrate. In addition, NiCo-NiO-CoO / NF-1 also performs better in water / heavy water electrolysis and hydrogen / deuterium evolution than metal organic framework precursors (NiCoBDC / NF, CoBDC / CF, and NiBDC / NF), indicating that nickel / cobalt-based metal organic frameworks are not ideal for water / heavy water electrolysis. Finally, NiCo-NiO-CoO / NF-1 was compared with NiCo-NiO-CoO-Bz / NF (with organic ligand replacement), ZnCo-ZnO-CoO / NF (with metal cation replacement), and ZnCo-NCNT / CC (with cobalt single-atom nitrogen-doped carbon). NiCo-NiO-CoO / NF-1 was found to offer the best performance for water / heavy water electrolysis for hydrogen / deuterium evolution. These performance improvements over the conductive substrate-free catalysts of the examples are significantly superior to those of the other metal-based catalysts used in the comparisons, demonstrating that nickel-cobalt alloy composite nickel-cobalt oxide materials can be easily grown in situ on conductive substrates, exhibit superior performance, and possess promising application potential.

[0176] Although the present invention has been described in detail above using general descriptions and specific embodiments, it will be apparent to those skilled in the art that modifications and improvements may be made thereto. Therefore, such modifications and improvements, without departing from the spirit of the present invention, are intended to be within the scope of protection claimed herein.

Claims

1. A method for preparing a nickel-cobalt alloy composite nickel-cobalt oxide material, characterized in that: The method comprises: Step 1: Mixing an inorganic cobalt salt, an inorganic nickel salt, and terephthalic acid in a mixed solution of deionized water and N,N-dimethylformamide into which a protective gas is continuously introduced to form a homogeneous solution; Step 2: placing the homogeneous solution obtained in step 1 alone or together with a conductive substrate in a reactor for a solvothermal reaction; after cooling to room temperature, collecting the solid powder or the in-situ self-grown material on the conductive substrate, washing, and drying the solid powder to obtain a nickel-doped cobalt terephthalate powder precursor or a nickel-doped cobalt terephthalate precursor in-situ grown on a conductive substrate; Step three, pyrolyzing the precursor obtained in step two at high temperature, washing and drying, and finally obtaining a nickel-cobalt alloy composite nickel-cobalt oxide powder material or a nickel-cobalt alloy composite nickel-cobalt oxide material in situ grown on a conductive substrate.

2. The method for preparing a nickel-cobalt alloy composite nickel-cobalt oxide material according to claim 1, characterized in that: In the step 1, the inorganic cobalt salt is one or more of cobalt chloride, cobalt nitrate, and cobalt sulfate; and the inorganic nickel salt is one or more of nickel chloride, nickel nitrate, and nickel sulfate.

3. The method for preparing a nickel-cobalt alloy composite nickel-cobalt oxide material according to claim 1, characterized in that: In the step 1, the molar ratio of the total amount of the inorganic cobalt salt and the inorganic nickel salt to terephthalic acid is 0.5-2:1; the molar ratio of the inorganic cobalt salt to the inorganic nickel salt is 6-1:1; and the molar ratio of deionized water to N,N-dimethylformamide is 1:1-4.

4. The method for preparing a nickel-cobalt alloy composite nickel-cobalt oxide material according to claim 1, characterized in that: In the step 1, the protective gas is nitrogen or argon.

5. The method for preparing a nickel-cobalt alloy composite nickel-cobalt oxide material according to claim 1, characterized in that: In the step 2, the reaction temperature of the solvent thermal reaction is 100-140° C., and the reaction time is 10-30 hours.

6. The method for preparing a nickel-cobalt alloy composite nickel-cobalt oxide material according to claim 1, characterized in that: In the step 3, the reaction temperature of the high temperature pyrolysis is 250-350° C., and the reaction time is 2-4 hours.

7. The method for preparing a nickel-cobalt alloy composite nickel-cobalt oxide material according to claim 1, characterized in that: In the step 3, the washing liquid is one or more of methanol, ethanol, water, acetone or isopropanol; and the drying is air drying, vacuum drying or freeze drying.

8. The preparation method according to claim 1, characterized in that: The conductive substrate is foamed nickel, foamed cobalt, carbon cloth, carbon paper, nickel foil or cobalt foil.

9. A nickel-cobalt alloy composite nickel-cobalt oxide material prepared by the method according to any one of claims 1 to 8, characterized in that: The material is a nanosheet composed of tightly connected nickel-cobalt alloy, nickel oxide and cobalt oxide.

10. Use of the nickel-cobalt alloy composite nickel-cobalt oxide material as claimed in claim 9 in electrocatalysis, characterized in that: The electrocatalyst is used in a hydrogen evolution reaction at a cathode end of water decomposition or a deuterium evolution reaction at a cathode end of heavy water decomposition.

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