Supported nickel-cobalt double-metal hydroxide catalyst as well as preparation method and application thereof

Abstract

The invention provides a supported nickel-cobalt double-metal hydroxide catalyst as well as a preparation method and application thereof, and belongs to the technical field of electrocatalysts and electrochemical organic synthesis. The supported nickel-cobalt double-metal hydroxide catalyst comprises nickel species and cobalt species, the nickel species and the cobalt species are co-crystallized to form layered nanosheets, and the layered nanosheets grow on a porous carrier. The cobalt species are introduced into the nickel hydroxide catalyst, more electrochemical active sites are provided through a layered nanosheet structure formed by the cobalt species and the nickel hydroxide catalyst, when the cobalt species and the nickel hydroxide catalyst are subsequently applied to electro-catalysis preparation of adipic acid, electron transfer between adsorbed cyclohexanone and the catalyst is enhanced, and the conversion rate of the catalyst to cyclohexanone is increased.

Description

Technical Field

[0001] This invention relates to the fields of electrocatalysts and electrochemical organic synthesis technology, and particularly to a supported nickel-cobalt bimetallic hydroxide catalyst, its preparation method, and its applications. Background Technology

[0002] Adipic acid (AA) is an important chemical raw material, mainly used in the production of two major polymers, nylon 66 and polyurethane. In recent years, it has also been used in the production of biodegradable plastics (PBAT), hexanediol, water-based coatings and food additives. It is widely used in the automotive, electronics, daily necessities, textile, pharmaceutical and food industries.

[0003] The related technologies use cyclohexane or cyclohexene as raw materials and nitric acid as an oxidant to prepare adipic acid. The reaction produces acidic waste liquid and the greenhouse gas nitrous oxide (N2O), which causes serious environmental pollution.

[0004] To address the aforementioned problems, green synthetic pathways such as hydrogen peroxide oxidation, biosynthesis, and electrocatalytic oxidation have been proposed. Among these, electrocatalytic oxidation uses electrons as the redox agent, eliminating the need for additional oxidants, operating under mild conditions, and producing no polluting gases. However, existing electrocatalytic synthesis methods for adipic acid suffer from insufficient catalyst conversion rates.

[0005] Therefore, a catalyst is needed that can be used for the electrocatalytic preparation of adipic acid and can improve the conversion rate of adipic acid. Summary of the Invention

[0006] In view of this, in order to at least partially solve the aforementioned technical problems, the present invention provides a supported nickel-cobalt bimetallic hydroxide catalyst, its preparation method, and its application.

[0007] According to one aspect of the present invention, a supported nickel-cobalt bimetallic hydroxide catalyst is provided, wherein the supported nickel-cobalt bimetallic hydroxide catalyst comprises: a nickel species and a cobalt species, wherein the nickel species and the cobalt species are co-crystallized to form layered nanosheets, and grown in the form of layered nanosheets on a porous support.

[0008] In some embodiments, betaine molecules are loaded onto the surface of the layered nanosheets of the nickel-cobalt bimetallic hydroxide catalyst.

[0009] In some embodiments, the porous carrier includes nickel foam.

[0010] In some implementations, the molar ratio of nickel species to cobalt species is (0.8~1.2):1.

[0011] According to another aspect of the present invention, a method for preparing the supported nickel-cobalt bimetallic hydroxide catalyst as described above is provided. The method includes: mixing and stirring cobalt salt or its hydrate, nickel salt or its hydrate, and urea in water to obtain a precursor solution; mixing a porous support and the precursor solution and heating them to carry out a hydrothermal reaction to prepare the supported nickel-cobalt bimetallic hydroxide catalyst.

[0012] In some embodiments, betaine compounds are added during the preparation of the precursor solution.

[0013] In some embodiments, the betaine compounds include at least one of cocamidopropyl betaine, lauryl betaine, and betaine monohydrate.

[0014] In some embodiments, the molar ratio of betaine compound to cobalt salt or its hydrate is 1:(4~6).

[0015] In some embodiments, the cobalt salt or its hydrate includes cobalt nitrate or its hydrate, and the nickel salt or its hydrate includes nickel nitrate or its hydrate.

[0016] In some embodiments, the molar ratio of cobalt salt or its hydrate to nickel salt or its hydrate is (0.8~1.2):1.

[0017] In some embodiments, the molar ratio of urea to cobalt salt or its hydrate is (10~15):1.

[0018] In some embodiments, the hydrothermal reaction temperature is 80~120℃ and the reaction time is 8~12h.

[0019] In some embodiments, the porous support is prepared by sequentially acid washing, water washing, and alcohol washing of the initial porous support to obtain the porous support.

[0020] According to another aspect of the present invention, an application of the supported nickel-cobalt bimetallic hydroxide catalyst as described above in the electrocatalytic preparation of adipic acid is provided.

[0021] According to embodiments of the present invention, the supported nickel-cobalt bimetallic hydroxide catalyst utilizes the similar ionic radii of nickel and cobalt, resulting in a uniform atomic-level mixture of nickel and cobalt ions. These ions co-crystallize to form layered nanosheets, which grow on a porous support. The introduction of cobalt species modulates the electron cloud density of nickel species, making them more readily oxidizable. This enhances the electrochemical activity for subsequent catalytic oxidation to adipic acid, exposing more electrocatalytic active sites. In subsequent electrocatalytic preparation of adipic acid, this strengthens electron transfer between the adsorbed cyclohexanone and the catalyst, improving the intrinsic catalytic activity and ultimately increasing the catalyst's conversion rate of cyclohexanone. Attached Figure Description

[0022] The above and other objects, features and advantages of the present invention will become clearer from the following description of embodiments of the invention with reference to the accompanying drawings.

[0023] Figure 1 The graphs showing the adipic acid yield and Faraday efficiency of the supported catalyst prepared in Example 1 of this invention at different potentials are illustrated.

[0024] Figure 2 The X-ray diffraction patterns of the betaine-modified supported nickel-cobalt bimetallic hydroxide catalyst (CoNi-LDH-BET) prepared in Example 2 of the present invention, and standard Co(OH)2 and standard Ni(OH)2 are shown.

[0025] Figure 3 The image shown is a scanning electron microscope image of CoNi-LDH-BET prepared in Example 2 of the present invention;

[0026] Figure 4 The elemental energy spectrum of CoNi-LDH-BET prepared in Example 2 of this invention is shown.

[0027] Figure 5 The Fourier transform infrared spectrum of CoNi-LDH-BET prepared in Example 2 of this invention is shown.

[0028] Figure 6 The graphs showing the adipic acid yield and Faraday efficiency of CoNi-LDH-BET prepared in Example 2 of this invention at different potentials are illustrated.

[0029] Figure 7 The bar charts showing the yield of adipic acid of the supported catalysts prepared in Examples 2 to 4 of the present invention at an electrode potential of 2.05 V vs. RHE are shown.

[0030] Figure 8 The diagram shows the open-circuit voltage change of the supported catalysts prepared in Examples 1 and 2 of this invention after the addition of cyclohexanone in the electrolytic cell. Detailed Implementation

[0031] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the invention. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of the invention for ease of explanation. However, it will be apparent that one or more embodiments may be practiced without these specific details. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0032] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. The term "comprising" as used herein indicates the presence of features, steps, or operations, but does not exclude the presence or addition of one or more other features.

[0033] Related technologies include the use of sodium alkyl sulfonate (SDS) modified nickel hydroxide as a catalyst (Ni(OH)2-SDS) to catalyze the preparation of adipic acid. However, the intrinsic activity of the catalyst is weak, and due to the oxidation of the catalyst, it exhibits a low adipic acid conversion rate.

[0034] In realizing the concept of this invention, it was discovered that by introducing cobalt species into a nickel hydroxide catalyst through co-crystallization, a layered nanosheet structure of nickel-cobalt bimetallic hydroxide catalyst is formed. Based on the electronic interaction between nickel and cobalt, the introduction of cobalt species reduces the Ni content. 2+ / Ni 3+ The oxidation potential of the adipic acid helps to promote the synergistic catalytic oxidation reaction, accelerates the conversion of the reaction intermediate into adipic acid, and improves the conversion rate of adipic acid.

[0035] Specifically, according to one embodiment of the present invention, a supported nickel-cobalt bimetallic hydroxide catalyst is provided, the nickel-cobalt bimetallic hydroxide catalyst comprising nickel species and cobalt species, the nickel species and cobalt species being co-crystallized to form layered nanosheets, and grown in the form of layered nanosheets on a porous support.

[0036] In this invention, "nickel species" and "cobalt species" can be understood as nickel and cobalt elements existing in ionic form and incorporated into the specific hydroxide crystal structure described above, which can coexist in the layered double hydroxide nanosheets in mixed valence states of +2 and +3, respectively.

[0037] In this invention, "layered nanosheets" can be understood as a two-dimensional, sheet-like stacked structure with nanoscale thickness exhibited by the active component (nickel-cobalt bimetallic hydroxide) of the supported catalyst, wherein nickel and cobalt are uniformly mixed at the atomic level and co-crystallized to form a two-dimensional planar structure. The layered nanosheets are electrostatically balanced and connected through anions and water molecules.

[0038] It is understandable that layered nanosheets, with a thickness between 1 and 100 nm, possess a high specific surface area. The structure of layered nanosheets can be confirmed using scanning electron microscopy images.

[0039] According to embodiments of the present invention, based on the similar ionic radii of nickel and cobalt, the introduction of cobalt can effectively regulate the electron cloud density of adjacent nickel atoms, making them easier to oxidize to a higher valence state. The co-crystallization of nickel and cobalt allows this process to occur at a lower overpotential, reducing the reaction energy barrier. The layered nanosheets expose a relatively large number of unsaturated coordinated metal sites, which is beneficial for the adsorption and activation of reactants. In addition, the direct growth method allows for a strong binding effect between the layered nanosheets and the conductive porous support. When used as a catalyst (i.e., the aforementioned supported nickel-cobalt bimetallic hydroxide catalyst) in the preparation of adipic acid from cyclohexanone, the nickel and cobalt sites have superior affinity and catalytic ability for the cyclohexanol / cyclohexanone catalytic oxidation and CH activation steps in the above process. Moreover, their atomic proximity promotes the rapid transfer and conversion of reaction intermediates between different metal sites, enhances the electron transfer between the adsorbed cyclohexanone and the catalyst, thereby reducing the activation energy of the cyclohexanone electro-oxidation reaction, enhancing the intrinsic catalytic activity of the catalyst, and increasing the conversion rate of cyclohexanone to the target product adipic acid.

[0040] In some embodiments, betaine molecules are loaded onto the surface of the layered nanosheets of the nickel-cobalt bimetallic hydroxide catalyst. Betaine is an amphoteric surfactant; its anionic end binds to the catalyst surface, while its cationic end and hydrophobic segments both repel water molecules and adsorb cyclohexanone. By loading betaine molecules, the enrichment and adsorption of cyclohexanone on the catalyst surface are further enhanced, thereby increasing the yield of subsequent applications in the electrocatalytic oxidation to prepare adipic acid.

[0041] In some embodiments, the porous support includes nickel foam. Nickel foam is a three-dimensional porous metallic material with high porosity. For example, in the electrocatalytic preparation of adipic acid from cyclohexanone, it allows reactants (e.g., cyclohexanone) and products (e.g., adipic acid) to diffuse freely to the inner and outer surfaces of the catalyst with low mass transfer resistance, thereby fully utilizing the active sites and improving catalyst utilization efficiency. Simultaneously, nickel foam has good thermal conductivity, preventing localized overheating. Furthermore, the electrical conductivity of nickel foam promotes rapid electron migration within the catalyst system.

[0042] In some implementations, the molar ratio of nickel to cobalt species is (0.8~1.2):1. This setting helps to enhance the electronic interaction between nickel and cobalt, and the presence of cobalt species can effectively stabilize and promote the interaction of Ni. 2+ Towards more active Ni 3 + / Ni 4+ The transformation requires a low overpotential. If the proportion of nickel species is too high, for example, greater than the upper limit mentioned above, the synergistic effect between the two will be weakened; if the proportion of nickel species is too low, for example, lower than the lower limit mentioned above, it may lead to premature oxidation of the catalyst, which is not conducive to the adsorption and transformation of intermediates.

[0043] Optionally, the molar ratio of nickel species to cobalt species may be, for example, 0.8:1, 0.9:1, 1:1, 1.1:1 or 1.2:1, or a range between any two of the above ratios.

[0044] Preferably, the molar ratio of nickel species to cobalt species is 1:1.

[0045] According to another aspect of the present invention, a method for preparing the supported nickel-cobalt bimetallic hydroxide catalyst as described above is provided, the method comprising steps 1 to 2.

[0046] In step 1, cobalt salt or its hydrate, nickel salt or its hydrate, and urea are mixed and stirred in water to obtain a precursor solution.

[0047] In step 2, the porous support and precursor solution are mixed and heated to carry out a hydrothermal reaction to prepare a supported nickel-cobalt bimetallic hydroxide catalyst.

[0048] According to an embodiment of the present invention, in step 1, the cobalt salt or its hydrate and the nickel salt or its hydrate are mixed to provide a basis for subsequent atomic-level uniform doping, which helps to achieve synergistic dual-site promotion of subsequent electrocatalytic oxidation by cobalt active sites and nickel active sites. Urea slowly hydrolyzes during the hydrothermal reaction, continuously releasing hydroxide ions (OH-). - ) and carbonate ions (CO3) 2- ), where OH - It reacts with cobalt and nickel ions to form hydroxide precipitates, CO3 2- As an anion, it is embedded in the interlayer space of layered bimetallic hydroxides, stabilizing their structure and slowly releasing OH-. - This makes the precipitation process relatively mild, which is conducive to the formation of a layered structure with high crystallinity and uniform morphology. The hydrothermal reaction in step 2 promotes the dissolution and recrystallization of the bimetallic hydroxide, improves the crystallinity of the co-crystallized nickel and cobalt species, and the hydrothermal reaction helps to regulate the morphology of the layered nanosheets, further optimize the specific surface area and pore structure, and further improve the conversion rate of cyclohexanone by the catalyst.

[0049] It is understandable that the hydrothermal reaction in step 2 is carried out by heating in a closed autoclave.

[0050] In some embodiments, betaine compounds are added during the preparation of the precursor solution. It is understood that during surfactant screening, it was found that amino acid surfactants and imidazoline surfactants are thermally unstable and prone to decomposition during synthesis. In contrast, the betaine compounds of this invention maintain their intact structure after the hydrothermal reaction. Furthermore, the betaine compounds are loaded onto the catalyst surface through coordination of the carboxyl terminus with nickel and / or cobalt metal sites, further enhancing the catalyst's enrichment effect on cyclohexanone.

[0051] In some embodiments, the betaine compounds include at least one of cocamidopropyl betaine, lauryl betaine, and betaine monohydrate. During the screening of betaine compounds, it was found that the above compounds showed relatively better enrichment effects on cyclohexanone.

[0052] Preferably, the betaine compound is cocamidopropyl betaine.

[0053] It is understandable that porous supports include nickel foam. This allows the nickel-cobalt bimetallic hydroxide catalyst to grow on the surface of the nickel foam framework and within its three-dimensional channels, increasing the number of active sites and thus enhancing catalytic activity.

[0054] In some embodiments, the molar ratio of betaine compound to cobalt salt or its hydrate is 1:(4~6). This setting allows the betaine compound to balance the dispersion effect of the catalyst and the hydrothermal reaction efficiency, and avoids the increase in system viscosity caused by excessive concentration of betaine compound.

[0055] Optionally, the molar ratio of the betaine compound to the cobalt salt or its hydrate may be, for example, 1:4, 1:5 or 1:6, or a range consisting of any two of the above ratios.

[0056] In some embodiments, the cobalt salt or its hydrate includes cobalt nitrate or its hydrate, and the nickel salt or its hydrate includes nickel nitrate or its hydrate. Cobalt nitrate or its hydrate, and nickel nitrate or its hydrate, have high solubility in water; mixing them helps promote atomic-level homogeneous mixing of cobalt and nickel ions in water, forming a homogeneous precursor solution.

[0057] For example, nickel nitrate or its hydrate can be, for example, nickel nitrate hexahydrate. Cobalt nitrate or its hydrate can be, for example, cobalt nitrate hexahydrate.

[0058] In some embodiments, the molar ratio of cobalt salt or its hydrate to nickel salt or its hydrate is (0.8~1.2):1. This arrangement, as previously mentioned, helps to enhance the electronic interaction between nickel and cobalt, and the presence of cobalt ions effectively stabilizes and promotes Ni… 2+ Towards more active Ni 3+ / Ni 4+ The conversion requires a low overpotential. If the proportion of cobalt salt or its hydrate is too high, for example, above the upper limit mentioned above, the synergistic effect of the two will be weakened; if the proportion of cobalt salt or its hydrate is too low, for example, below the lower limit mentioned above, it may cause premature oxidation of the catalyst, which is not conducive to the adsorption and conversion of intermediates.

[0059] In some embodiments, when the cobalt salt or its hydrate is cobalt nitrate hexahydrate, the molar ratio of urea to the cobalt salt or its hydrate is (10~15):1. This configuration utilizes the alkaline environment provided by urea to create reaction conditions for the co-crystallization of nickel nitrate and cobalt nitrate hexahydrate into nickel and cobalt species, respectively. If there is too little urea, it becomes difficult for nickel and cobalt ions to transform into nickel and cobalt species, respectively; if there is too much urea, it easily produces inactive basic carbonates.

[0060] Optionally, the molar ratio of urea to cobalt salt or its hydrate may be, for example, 10:1, 11:1, 12:1, 13:1, 14:1 or 15:1, or a range consisting of any two of the above ratios.

[0061] In some embodiments, the hydrothermal reaction temperature is 80–120°C, and the reaction time is 8–12 hours. This setup ensures stable hydrolysis of urea, promotes the complete conversion of cobalt salts or their hydrates, and nickel salts or their hydrates into intermediate products such as nickel hydroxide or cobalt hydroxide, and further co-crystallizes under hydrothermal conditions to obtain a nickel-cobalt bimetallic hydroxide catalyst. Furthermore, the aforementioned temperature and time ranges facilitate the nucleation and growth of nickel-cobalt bimetallic hydroxide catalyst crystals.

[0062] Alternatively, the temperature of the hydrothermal reaction can be, for example, 80°C, 100°C, or 120°C, or a range consisting of any two of the above values.

[0063] Alternatively, the hydrothermal reaction time can be, for example, 8h, 10h, or 12h, or a range between any two of the above values.

[0064] In some embodiments, the porous support is prepared by sequentially acid washing, water washing, and alcohol washing of the initial porous support. This arrangement helps to clean and activate the porous support, promoting more uniform and robust growth of the nickel-cobalt bimetallic hydroxide catalyst on the inner and outer surfaces of the porous support, thereby improving the catalyst's cycle life.

[0065] In one specific implementation, the porous support can, for example, be 2 mol·L⁻¹. -1 Ultrasonic cleaning with hydrochloric acid, deionized water and ethanol for 5 minutes.

[0066] According to another aspect of the present invention, an application of the supported nickel-cobalt bimetallic hydroxide catalyst as described above in the electrocatalytic preparation of adipic acid is provided.

[0067] According to an embodiment of the present invention, under the action of the catalyst of the present invention, adipic acid is produced by electrocatalysis using cyclohexanone as the reaction substrate. The catalyst of the present invention is based on the introduction of cobalt species, which together with nickel active sites enhance the intrinsic catalytic activity of the catalyst, improve the conversion rate of cyclohexanone to the catalyst, and improve the yield of adipic acid.

[0068] Furthermore, by loading betaine molecules onto the surface of layered nanosheets, this invention helps to further enhance the enrichment and adsorption of cyclohexanone at nickel and cobalt active sites, thereby further improving the yield of adipic acid.

[0069] In one specific embodiment, the electrocatalytic preparation of adipic acid using cyclohexanone as a substrate by the present invention achieves a yield of 0.931 mmol·h per unit area and per unit time. -1 ·cm -2 This is significantly higher than the product yield of nickel hydroxide modified with sodium alkyl sulfonate in related technologies (under roughly the same electrocatalytic conditions, the product yield is 0.26 mmol·h⁻¹). -1 ·cm -2 This demonstrates that the method of the present invention enables the efficient and highly selective synthesis of adipic acid during the electrocatalytic oxidation of cyclohexanone.

[0070] The present application is further illustrated below through embodiments, accompanying drawings, and related test experiments and results. In the following detailed description, numerous specific details are set forth for ease of explanation to provide a comprehensive understanding of the embodiments of the present application. However, it is apparent that one or more embodiments may be implemented without these specific details. Moreover, the details in the following embodiments can be arbitrarily combined to form other feasible embodiments without conflict.

[0071] It should be noted that the specific embodiments described below are merely illustrative examples, and the scope of protection of this application is not limited thereto. The chemicals and raw materials used in the following embodiments are all commercially available or prepared using recognized processing methods.

[0072] Example 1:

[0073] Preparation of supported nickel-cobalt bimetallic hydroxide catalysts (referred to as supported catalysts):

[0074] Carrier pretreatment: Nickel foam (2cm × 2cm) was sequentially treated with 2 mol·L⁻¹ water. -1 Ultrasonic cleaning with hydrochloric acid, deionized water and ethanol for 5 minutes.

[0075] Precursor solution

[0076] Preparation of precursor solution: Dissolve 300 mg of cobalt nitrate hexahydrate (Co(NO3)2·6H2O), 300 mg of nickel nitrate hexahydrate (Ni(NO3)2·6H2O), and 800 mg of urea (CO(NH2)2) in deionized water, stir and mix to obtain the precursor solution.

[0077] Hydrothermal reaction: The nickel foam and precursor solution were placed in a Teflon-lined autoclave and reacted at 100°C for 10 hours.

[0078] Post-processing: Remove the nickel foam loaded with catalyst, wash and dry it, and cut it into electrodes (1cm×1cm) for later use.

[0079] The supported catalyst prepared in Example 1 was used as the working electrode, graphite or carbon paper as the counter electrode, and an Hg / HgO electrode as the reference electrode, containing 0.4 mol·L⁻¹ -1 1 mol·L of cyclohexanone -1 The KOH solution was used as the electrolyte, and the electrolysis reaction was carried out in a laboratory H-type electrolytic cell.

[0080] The reaction equation for the oxidation of cyclohexanone to adipic acid in an electrolytic cell is shown below:

[0081] .

[0082] The electrolysis reaction was carried out in an H-type electrolytic cell under constant potential, with the potential controlled in the range of 1.75V~2.05V vs. RHE (reversible hydrogen electrode potential). Figure 1 The diagram shows the adipic acid yield and Faradaic efficiency of the supported catalyst prepared in Example 1 of this invention at different potentials, where the bar chart corresponds to the yield and the line graph corresponds to the Faradaic efficiency. Figure 1 As shown, the cyclohexanone substrate is confirmed to be oxidized to adipic acid at the anode, with the relatively optimal conditions being 2.05 V vs. RHE. The Faraday efficiency plot reveals a high electron utilization efficiency for the target product (i.e., adipic acid) in the electrode reaction, indicating that electrons are concentrated in the formation of the target product with fewer side reactions. It is understandable that Faraday efficiency, based on Faraday's law, primarily calculates the ratio of the amount of electricity consumed in the formation of the target product to the total amount of electricity passed. Furthermore, the adipic acid yield at this point is higher than the 0.26 mmol·h⁻¹ yield achieved under similar conditions using a sodium alkyl sulfonate-modified Ni(OH)₂ catalyst (i.e., Ni(OH)₂-SDS). -1 ·cm -2 .

[0083] Example 2:

[0084] The preparation steps of Example 2 are generally the same as those of Example 1. The difference is that cocamidopropyl betaine is added during the preparation of the precursor solution in Example 2, and the molar ratio of the amount of cocamidopropyl betaine added to cobalt nitrate hexahydrate is 1:5, so as to prepare a betaine-modified supported nickel-cobalt bimetallic hydroxide catalyst (designated as CoNi-LDH-BET).

[0085] Example 3:

[0086] The preparation steps of Example 3 are generally the same as those of Example 2, except that cocamidopropyl betaine is replaced with lauryl betaine in Example 3.

[0087] Example 4:

[0088] The preparation steps of Example 4 are generally the same as those of Example 2, except that cocamidopropyl betaine is replaced with betaine monohydrate in Example 4.

[0089] Figure 2 The X-ray diffraction patterns of the betaine-modified supported nickel-cobalt bimetallic hydroxide catalyst (CoNi-LDH-BET) prepared in Example 2 of this invention, and those of standard Co(OH)₂ and standard Ni(OH)₂ are shown. Figure 2 As shown, it can be seen that the peak positions in Example 2 are completely matched with those of standard Co(OH)2 and standard Ni(OH)2, and no other species peaks were observed, indicating that the obtained nickel and cobalt species form a nickel-cobalt bimetallic hydroxide structure through co-crystallization.

[0090] Figure 3 The image shown is a scanning electron microscope image of CoNi-LDH-BET prepared in Example 2 of the present invention. Figure 4 The elemental energy spectrum of CoNi-LDH-BET prepared in Example 2 of this invention is shown. Figure 3 As shown, the CoNi-LDH-BET of Example 2 has a layered nanosheet structure, on which dendrites formed by the action of betaine are present. Figure 4 As can be seen from the diagram, the cobalt species, nickel species, and carbon elements from betaine are all evenly distributed.

[0091] Figure 5 The Fourier transform infrared spectrum of CoNi-LDH-BET prepared in Example 2 of this invention is shown. Figure 5 As shown, it can be seen that CoNi-LDH-BET in Example 2 has a significant betaine absorption peak at 1545 cm⁻¹. -1The characteristic peak at this location corresponds to the stretching vibration of the NH bond on the amide, which is direct evidence of the presence of cocamidopropyl betaine and confirms the loading of betaine on the catalyst surface. Through the above... Figures 2-5 Together, they demonstrated the successful synthesis of CoNi-LDH-BET.

[0092] The electrocatalytic system was constructed using the same method as in Example 1, with the supported catalysts prepared in Examples 2 through 4 used as working electrodes. The electrolysis reaction was carried out in an H-type electrolytic cell using the same method as in Example 1. Figure 6 The diagram shows the adipic acid yield and Faradaic efficiency of CoNi-LDH-BET prepared in Example 2 of this invention at different potentials, where the bar chart corresponds to the yield and the line graph corresponds to the Faradaic efficiency. Figure 6 As shown, the reversible hydrogen electrode potential is preferably 2.05 V vs. RHE, confirming that the cyclohexanone substrate is oxidized to adipic acid at the anode. The Faraday efficiency plot shows that the electron utilization efficiency of the target product (i.e., adipic acid) is high in the electrode reaction, indicating that it is concentrated in the formation of the target product with fewer side reactions. Furthermore, Example 2 exhibits higher reactivity and yield compared to Example 1.

[0093] Figure 7 The bar charts showing the yield of adipic acid of the supported catalysts prepared in Examples 2-4 of this invention at an electrode potential of 2.05 V vs. RHE are illustrated. Figure 7 As shown, Examples 2 through 4 all exhibit significant improvements compared to Example 1. This is due to the introduction of betaine, which further enhances the enrichment and adsorption of the reaction substrate cyclohexanone, increasing the reaction yield and thus promoting the formation of more adipic acid. A comparison of Examples 2 through 4 reveals that the supported catalyst in Example 2 possesses relatively higher catalytic oxidation performance.

[0094] The supported catalysts prepared in Examples 1 and 2 of this invention were then applied to an electrolytic cell for testing. Figure 8 The diagram shows the open-circuit voltage changes of the supported catalysts prepared in Examples 1 and 2 of this invention after the addition of cyclohexanone in an electrolytic cell. Figure 8 As shown, after adding cyclohexanone to the KOH electrolyte, the open-circuit voltage of the catalyst in Example 2 decreased significantly compared to that of the catalyst in Example 1. The open-circuit voltage of Example 2 decreased by 67.4 mV, while that of Example 1 decreased by 57.6 mV. The change in open-circuit voltage of Example 2 was 9.8 mV greater than that of Example 1, indicating that Example 2 more effectively achieved the enrichment of cyclohexanone on the catalyst surface.

[0095] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A supported nickel-cobalt bimetallic hydroxide catalyst, wherein, The nickel-cobalt bimetallic hydroxide catalyst comprises nickel and cobalt species, which are co-crystallized to form layered nanosheets, which are then grown on a porous support in the form of layered nanosheets.

2. The supported nickel-cobalt bimetallic hydroxide catalyst according to claim 1, wherein, The layered nanosheets of the nickel-cobalt bimetallic hydroxide catalyst are loaded with betaine molecules. The porous carrier includes nickel foam.

3. The supported nickel-cobalt bimetallic hydroxide catalyst according to claim 1, wherein, The molar ratio of nickel species to cobalt species is (0.8~1.2):

1.

4. A method for preparing a supported nickel-cobalt bimetallic hydroxide catalyst as described in any one of claims 1 to 3, wherein, The preparation method includes: A precursor solution is obtained by mixing and stirring cobalt salt or its hydrate, nickel salt or its hydrate, and urea in water; The supported nickel-cobalt bimetallic hydroxide catalyst is prepared by mixing and heating the porous support and the precursor solution to carry out a hydrothermal reaction.

5. The preparation method according to claim 4, wherein, In the process of preparing the precursor solution, betaine compounds are also added.

6. The preparation method according to claim 5, wherein, The betaine compounds include at least one of cocamidopropyl betaine, lauryl betaine, and betaine monohydrate; and / or, The molar ratio of the betaine compound to the cobalt salt or its hydrate is 1:(4~6).

7. The preparation method according to claim 4, wherein, The cobalt salt or its hydrate includes cobalt nitrate or its hydrate, and the nickel salt or its hydrate includes nickel nitrate or its hydrate; and / or, The molar ratio of the cobalt salt or its hydrate to the nickel salt or its hydrate is (0.8~1.2):1; and / or, The molar ratio of urea to the cobalt salt or its hydrate is (10~15):

1.

8. The preparation method according to claim 4, wherein, The hydrothermal reaction is carried out at a temperature of 80~120℃ for 8~12h.

9. The preparation method according to claim 4, wherein, The porous support was prepared by the following method; The initial porous support was sequentially subjected to acid washing, water washing, and alcohol washing to obtain the porous support.

10. The application of a supported nickel-cobalt bimetallic hydroxide catalyst as described in any one of claims 1 to 3 in the electrocatalytic preparation of adipic acid.

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