Bifunctional oer / her water electrolysis catalyst, method of making and use thereof
By loading a NiO@Co3O4 core-shell structure NiO@Co3O4/CF catalyst onto three-dimensional foamed carbon, the problems of high cost of precious metal catalysts and poor activity of single transition metal oxides are solved, and efficient and stable water electrolysis catalytic performance is achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHANGHAI UNIV
- Filing Date
- 2023-06-08
- Publication Date
- 2026-07-03
AI Technical Summary
In the existing technology, noble metal-based catalysts are expensive and scarce, single transition metal oxides perform poorly in catalyzing hydrogen evolution and oxygen evolution reactions, and the stability and activity of OER and HER are mismatched in the same electrolyte solution, resulting in poor performance of the electrolyzer.
By employing solvothermal and heat treatment techniques, NiO@Co3O4 core-shell structures were loaded onto three-dimensional foamed carbon to form a three-dimensional self-supporting hierarchical porous nanocomposite material NiO@Co3O4/CF, which serves as a bifunctional OER/HER water electrolysis catalyst.
Under alkaline conditions, the catalyst exhibits both high hydrogen evolution and oxygen evolution activity, low overpotential, and good stability. It can be used as both anode and cathode in the same electrolyte for water electrolysis, thereby reducing the overall energy consumption of water electrolysis.
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Figure CN116676626B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of nanomaterials and electrochemistry, and relates to a bifunctional OER / HER water electrolysis catalyst for water electrolysis, its preparation method and its application. Background Technology
[0002] Hydrogen energy, with its high calorific value, good combustion performance, clean and pollution-free nature, and diverse production, storage, and utilization methods, is a clean energy source with great development potential and is of great significance for achieving sustainable and coordinated development of energy and the environment. Among the current major hydrogen production methods, water electrolysis, as an important method for producing hydrogen, has attracted much attention due to its advantages such as simple preparation method, wide availability of raw materials, and high product purity. Water electrolysis involves two half-reactions: the hydrogen evolution reaction (HER) at the cathode and the oxygen evolution reaction (OER) at the anode. Because HER and OER have high activation barriers, they are not easily thermodynamically determined. Therefore, under alkaline conditions, water electrolyzers typically require a higher voltage of 1.8-2.0V to operate, while the theoretical limiting voltage for water electrolysis is only 1.23V.
[0003] In existing technologies, noble metal-based catalysts such as RuO2 and Pt / C can effectively catalyze oxygen evolution and hydrogen evolution reactions, respectively, but their high cost and scarcity severely limit their large-scale application and commercial promotion. It is worth noting that generally, good OER catalysts exhibit poor HER activity, and vice versa. Furthermore, in the same electrolyte solution, the pH ranges of the two electrocatalysts used for OER and HER respectively at their stable and most active states often do not match, leading to poor overall performance of the electrolyzer. However, using highly efficient OER / HER bifunctional electrocatalysts can improve the sluggish reaction kinetics and reduce the overpotentials of OER and HER, thereby improving the overall performance of the system. Therefore, in-depth research on non-noble metal OER / HER bifunctional catalysts is of great significance for developing stable and efficient water electrolysis catalysts.
[0004] Transition metals, due to their abundant reserves, low cost, and unique d-electron structure, have become potential alternatives to noble metal catalysts. Compounds based on transition metals, such as oxides, hydroxides, sulfides, phosphides, nitrides, and alloys, have been extensively studied in catalysis of hydrogen evolution and oxygen evolution reactions (HER). Among them, transition metal oxides, with their unique redox properties, diverse structures, and variable valence states, exhibit excellent OER catalytic performance under alkaline conditions. However, single transition metal oxides often exhibit poor HER performance. Therefore, the construction and synthesis of bifunctional catalysts capable of simultaneously and efficiently catalyzing both hydrogen evolution and oxygen evolution reactions is of great significance for water electrolysis applications. Summary of the Invention
[0005] To address the problems existing in the prior art, this invention provides a bifunctional OER / HER water electrolysis catalyst, its preparation method, and its application. Through a novel concept, a three-dimensional self-supporting non-precious metal-based OER / HER water electrolysis catalyst with a core-shell structure, NiO-NS@Co3O4-NW / CF (hereinafter abbreviated as NiO@Co3O4 / CF), is prepared. This catalyst can exhibit both highly efficient hydrogen evolution and oxygen evolution catalytic activity and stability under alkaline conditions.
[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:
[0007] A bifunctional OER / HER water electrolysis catalyst is characterized in that it is a three-dimensional self-supporting transition metal-based OER / HER catalyst, which is composed of two transition metal oxides and a conductive support. The composite metal oxides are in situ loaded onto conductive three-dimensional foam carbon through a solvothermal method and heat treatment to form a core-shell heterostructure three-dimensional self-supporting hierarchical porous nanocomposite material.
[0008] The bifunctional OER / HER water electrolysis catalyst is characterized in that it is a three-dimensional self-supporting NiO@Co3O4 / CF catalyst. This catalyst is a three-dimensional self-supporting hierarchical porous nanocomposite material NiO@Co3O4 / CF obtained by combining a transition metal-based oxide and a core-shell structured NiO@Co3O4 with three-dimensional foamed carbon as a support. The core-shell structured NiO@Co3O4 is obtained by using Co3O4 as the core and forming a shell layer of NiO nanosheets uniformly loaded in situ on the Co3O4, which is then coated with Co3O4 nanowires. This core-shell structure is the active component in the catalyst.
[0009] A method for preparing the bifunctional OER / HER water electrolysis catalyst, characterized by comprising the following steps:
[0010] S1: Preparation of three-dimensional foamed carbon support using carbonized melamine foam: in 100 mL min -1 Under a nitrogen flow, melamine foam (MF) was heated to 700°C and held at that temperature for 1 hour. After cooling to room temperature, black three-dimensional foamed carbon (CF) was obtained.
[0011] S2: Preparation of foam carbon supported on nickel@cobalt precursors: Dissolve appropriate amounts of cobalt salt, urea, and CTAB in water and sonicate for 5-10 minutes to obtain a transparent solution. Measure the foam carbon in size 2×2cm... 2After the foamed carbon is immersed in the solution, it is transferred to the hydrothermal reactor for the first step of hydrothermal reaction to obtain foamed carbon loaded with cobalt precursor. After washing, it is immersed in an ethanol solution containing nickel salt and urea and transferred as a whole to the reactor for the second step of hydrothermal reaction. After cooling to room temperature, the foamed carbon loaded with nickel@cobalt precursor is washed to obtain the foamed carbon.
[0012] S3: Catalyst preparation: Foamed carbon loaded with nickel@cobalt precursor was placed in a tube furnace and calcined at 350°C for 1 hour. After cooling to room temperature, NiO@Co3O4 / CF catalyst was obtained.
[0013] The advantages of this invention are:
[0014] 1. This invention rationally designs the composition and structure of a self-supporting non-precious metal-based catalyst, which is a three-dimensional self-supporting hierarchical porous nanocomposite material. This facilitates electrolyte transport and charge storage during the catalytic process, increasing the catalyst's surface area. Compared to single metal oxides, the synthesized NiO@Co3O4 / CF has abundant oxygen vacancies. The synergistic effect between its Co3O4-NW core layer and NiO-NS shell layer, as well as the interaction between its overall core-shell structure and the three-dimensional foamed carbon, can alter the electronic structure of the catalyst surface, improving its catalytic activity for hydrogen evolution and oxygen evolution. Furthermore, using three-dimensional foamed carbon with high conductivity and porosity as a substrate can enhance electron transfer and promote the release of generated hydrogen and oxygen bubbles.
[0015] 2. This invention employs a two-step hydrothermal method followed by calcination to prepare a core-shell structure (NiO@Co3O4 / CF) of cobalt oxide nanowires@nickel oxide nanosheets grown in situ on three-dimensional carbon foam (CF) as a bifunctional catalyst for water electrolysis under alkaline conditions. The synergistic effect between the NiO-NS shell and the Co3O4-NW core, as well as the interaction with the three-dimensional carbon foam, effectively enhances the catalytic performance for hydrogen evolution and oxygen evolution. The unique core-shell structure and abundant oxygen vacancies of the NiO@Co3O4 composite material facilitate the exposure of more active sites and increase the electrochemical active area. Compared to powdered catalysts, the three-dimensional carbon foam, as a self-supporting catalyst with a conductive substrate, avoids the adverse effects of binders on the catalyst, further improving its catalytic activity and chemical stability. The metal oxide composite material is low-cost, has a simple and feasible synthesis process, and can simultaneously serve as both a cathode and anode in the same electrolyte for water electrolysis.
[0016] 3. The preparation method of this invention is highly operable, and the raw materials are abundant and inexpensive. The method is simple and feasible, and the raw materials are inexpensive and plentiful.
[0017] 4. The catalyst prepared by this invention can efficiently catalyze the hydrogen evolution reaction and oxygen evolution reaction under alkaline medium. It can also simultaneously serve as both anode and cathode in the same electrolyte for water electrolysis, and exhibits good stability.
[0018] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Attached Figure Description
[0019] Figure 1 Images (a) and (b) are scanning electron microscope (SEM) images of NiO@Co3O4 / CF obtained in Example 1 of this invention.
[0020] Figure 2 The images shown are transmission electron microscope (TEM) images (a) and high-resolution transmission electron microscope (HRTEM) images (b) of NiO@Co3O4 / CF obtained in Example 1 of this invention.
[0021] Figure 3 The image shows the X-ray energy dispersive spectroscopy (EDS) of NiO@Co3O4 / CF obtained in Example 1 of this invention.
[0022] Figure 4 (a) is a comparison of the oxygen evolution reaction polarization curves of NiO@Co3O4 / CF obtained in Example 1 of the present invention with those of Comparative Example 1 (Co3O4 / CF), Comparative Example 2 (NiO / CF) and pure nickel foam catalyst under alkaline conditions of 1.0 MKOH.
[0023] Figure 4 (b) is a comparison of the hydrogen evolution reaction polarization curves of NiO@Co3O4 / CF obtained in Example 1 of the present invention with those of Comparative Example 1 (Co3O4 / CF), Comparative Example 2 (NiO / CF) and pure nickel foam catalyst under alkaline conditions of 1.0 MKOH.
[0024] Figure 5 The NiO@Co3O4 / CF electrolysis device obtained in Example 1 of this invention, which simultaneously serves as both cathode and anode, is an example of this invention. (-) / / NiO@Co3O4 / CF (+) The total hydrolysis polarization curve (a) and stability test graph (b) are shown. Detailed Implementation
[0025] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.
[0026] Example
[0027] The bifunctional OER / HER water electrolysis catalyst provided in this embodiment is a three-dimensional self-supporting transition metal-based OER / HER catalyst, which is composed of two transition metal oxides and a conductive support. The composite metal oxides are loaded in situ onto conductive three-dimensional foam carbon through solvothermal method and heat treatment to form a core-shell heterostructure three-dimensional self-supporting hierarchical porous nanocomposite material.
[0028] The aforementioned bifunctional OER / HER water electrolysis catalyst is a three-dimensional self-supporting NiO@Co3O4 / CF catalyst. This catalyst is a three-dimensional self-supporting hierarchical porous nanocomposite material NiO@Co3O4 / CF obtained by combining a transition metal-based oxide and a core-shell structured NiO@Co3O4 with three-dimensional foamed carbon as a support. The core-shell structured NiO@Co3O4 is formed by using Co3O4 as the core and uniformly loading NiO nanosheets on Co3O4 in situ to form a shell layer, which then coats Co3O4 nanowires to obtain the core-shell structured NiO@Co3O4. This core-shell structure is the active component in the catalyst.
[0029] The catalyst is composed of three-dimensional self-supporting foam carbon supported transition metal oxide Co3O4 nanowires@NiO nanosheets, wherein the Co3O4 core layer has a nanowire structure with a length of 3-5 μm and a diameter of 100-200 nm, and is uniformly distributed on the framework of the three-dimensional foam carbon support.
[0030] The NiO shell has a nanosheet morphology with an average size of 200-500 nm and a thickness of 10-50 nm.
[0031] A method for preparing the bifunctional OER / HER water electrolysis catalyst includes the following steps:
[0032] S1: Preparation of three-dimensional foamed carbon support using carbonized melamine foam: in 100 mL min -1 Under a nitrogen flow, melamine foam (MF) was heated to 700°C and held at that temperature for 1 hour. After cooling to room temperature, black three-dimensional foamed carbon (CF) was obtained.
[0033] S2: Preparation of foam carbon supported on nickel@cobalt precursors: Dissolve appropriate amounts of cobalt salt, urea, and CTAB in water and sonicate for 5-10 minutes to obtain a transparent solution. Measure the foam carbon in size 2×2cm... 2 After being immersed in the solution, the foamed carbon was transferred to a hydrothermal reactor for the first hydrothermal reaction to obtain foamed carbon loaded with cobalt precursor. After washing, it was immersed in an ethanol solution containing nickel salt and urea and then transferred as a whole to the reactor for the second hydrothermal reaction. After cooling to room temperature, the foamed carbon loaded with nickel@cobalt precursor was washed to obtain foamed carbon. The cobalt salt was Co(NO3)2·6H2O, and the nickel salt was Ni(NO3)2·6H2O.
[0034] S3: Catalyst Preparation: Foamed carbon loaded with nickel@cobalt precursors was calcined at 350℃ and held at that temperature for 1 hour in a tube furnace. After cooling to room temperature, NiO@Co3O4 / CF catalyst was obtained. The hydrothermal conditions for in-situ growth of cobalt nanowires on foamed carbon were 160℃ for 1 hour. The hydrothermal conditions for the formation of nickel nanosheets were 90℃ for 10 hours.
[0035] An application of the aforementioned bifunctional OER / HER water electrolysis catalyst in the water electrolysis reaction, specifically a three-dimensional self-supporting NiO@Co3O4 / CF catalyst.
[0036] The described three-dimensional self-supporting NiO@Co3O4 / CF catalyst has dual functions in water electrolysis, achieving an oxygen evolution reaction and hydrogen evolution reaction rate of 10 mA / cm² under alkaline conditions. -2 The required overpotentials for the current densities are 195mV and 103mV, respectively.
[0037] The aforementioned three-dimensional self-supporting NiO@Co3O4 / CF catalyst has dual water electrolysis functions. When used as both cathode and anode in the same alkaline electrolysis cell, it can achieve 10 mA / cm² at a voltage of 1.53V. -2 It has a high current density and can operate stably.
[0038] More specifically, a method for preparing the aforementioned bifunctional OER / HER water electrolysis catalyst includes the following steps:
[0039] At 100 mL min -1 Carbon foam (CF) was prepared by carbonizing melamine foam (MF) under a nitrogen flow. Initially, the flow rate was 5°C for 1 minute. -1 The heating rate was such that the temperature was raised to 300°C in a tube furnace and held for 5 minutes, then increased by 1°C per minute. -1 The heating rate was increased further until the temperature reached 400℃ and held for 5 minutes. Finally, the temperature was increased by 2℃ / min. -1 The heating rate was further increased to 700℃ and held for 1 hour to obtain carbonized black three-dimensional foam carbon.
[0040] Add appropriate amounts of Co(NO3)2·6H2O, CO(NH2)2 and CTAB sequentially to 35 mL of deionized water, and sonicate for 5 minutes to obtain a transparent pink solution A.
[0041] Immerse approximately 6 mg of foamed carbon in solution A, then transfer the system to a 50 mL hydrothermal reactor, heat to an appropriate temperature and hold for an appropriate time, then cool to room temperature;
[0042] The obtained foamed carbon-supported Co nanowire precursor was washed with water and ethanol 3-5 times to remove excess surfactants and free ions.
[0043] Add appropriate amounts of Ni(NO3)2·6H2O and CO(NH2)2 sequentially to 35 mL of ethanol solution, and sonicate for 5 minutes to obtain a transparent light green solution B.
[0044] The foamed carbon loaded with Co nanowire precursor was immersed in solution B, the system was transferred to a 50 mL hydrothermal reactor, heated to an appropriate temperature and held for an appropriate time, and then cooled to room temperature.
[0045] The resulting cobalt@nickel loaded foam carbon was washed 3-5 times with water and ethanol, respectively, and then dried in an oven at 60°C.
[0046] The dried foamed carbon loaded with cobalt@nickel was placed in a tube furnace and inert nitrogen gas was introduced, and the furnace was heated at 5°C for 1 minute. -1 The temperature was increased to an appropriate level at a certain heating rate and held for an appropriate time. The system was then cooled to room temperature to obtain the final product, NiO@Co3O4 / CF catalyst.
[0047] Example 1
[0048] See appendix Figure 1-5 Based on the foregoing embodiments, the high-efficiency OER / HER bifunctional water electrolysis catalyst (NiO@Co3O4 / CF) and its preparation method provided in this embodiment are as follows:
[0049] 0.0873 g of Co(NO3)2·6H2O, 0.06 g of CO(NH2)2 and 0.225 g of CTAB were added sequentially to 35 mL of deionized water. After sonication for 5 minutes, a transparent pink solution A was obtained.
[0050] The size is 2×2cm 2 The foamed carbon was immersed in solution A, and then the system was transferred to a 50 mL hydrothermal reactor, heated to 160 °C and held at that temperature for 1 h. The system was then cooled to room temperature.
[0051] The obtained foam carbon loaded with Co nanowire precursor was washed three times with water and ethanol, respectively, to remove excess surfactant and free ions.
[0052] 0.0967g Ni(NO3)2·6H2O and 0.06g CO(NH2)2 were added sequentially to 35mL of ethanol solution, and the solution was sonicated for 5 minutes to obtain a transparent light green solution B.
[0053] The foamed carbon loaded with Co nanowire precursor was immersed in solution B, and then the system was transferred to a 50 mL hydrothermal reactor, heated to 90 °C and held for 10 h, and then the system was cooled to room temperature.
[0054] The obtained foam carbon loaded with cobalt and nickel was washed three times with water and ethanol respectively, and then dried overnight in an oven at 60°C.
[0055] The dried foamed carbon loaded with cobalt and nickel was placed in a tube furnace, and inert nitrogen gas was introduced, and the furnace was heated at 5°C for 1 minute. -1 The temperature was increased to 350℃ and held for 1 hour, and then the system was cooled to room temperature to obtain the final product NiO@Co3O4 / CF.
[0056] The microstructure of the NiO@Co3O4 / CF catalyst prepared in this embodiment based on carbon foam is shown in the attached figure. Figure 1 , 2 As shown.
[0057] From the appendix Figure 1 , 2 It can be seen that a NiO@Co3O4 core-shell structure was successfully and uniformly grown on the framework of three-dimensional carbon foam. (See attached image) Figure 3 The EDS analysis clearly indicates the presence of Co and Ni, with a Co:Ni atomic ratio of 13:5. (Appendix) Figure 4 (a) shows that NiO@Co3O4 / CF catalyzes OER in alkaline media at current densities of 10 and 100 mA / cm². -2 At these times, the overpotentials are as low as 195 and 283 mV, indicating that this catalyst exhibits excellent OER performance. It demonstrates superior OER activity. (See attached image.) Figure 4 Figure (b) shows that when NiO@Co3O4 / CF catalyzes HER in an alkaline medium, at a current density of 10 mA cm⁻¹, -2 At this time, the overpotential was only 103 mV, indicating that this catalyst has excellent HER performance. When the NiO@Co3O4 / CF catalyst is used as both the cathode and anode of a water electrolysis device, it is assembled into NiO@Co3O4 / CF. (-) / / NiO@Co3O4 / CF (+) When using a full hydrolysis electrolytic cell, attached Figure 5 The polarization curve in (a) shows that this full cell requires only 1.53V to achieve 10mA / cm. -2 The current density is high, and it can operate stably for more than 42 hours (see attached image). Figure 5 (b)
[0058] In other embodiments of the present invention, the aforementioned two-step hydrothermal method and subsequent calcination method can also be used to prepare a core-shell structure NiO-NS@Co3O4-NW (abbreviated as NiO@Co3O4 / CF catalyst) of cobalt oxide nanowires@nickel oxide nanosheets grown in situ on three-dimensional carbon foam (CF), which can be used as a bifunctional catalyst for water electrolysis under alkaline conditions.
[0059] Comparative Example 1
[0060] This comparative example prepares a similar Co3O4-NW / CF catalyst and compares it with that of Example 1.
[0061] 0.0873 g of Co(NO3)2·6H2O, 0.06 g of CO(NH2)2 and 0.225 g of CTAB were added sequentially to 35 mL of deionized water. After sonication for 5 minutes, a transparent pink solution A was obtained.
[0062] The size is 2×2cm 2 The foamed carbon was immersed in solution A, and then the system was transferred to a 50 mL hydrothermal reactor, heated to 160 °C and held for 1 h, and then the system was cooled to room temperature.
[0063] The obtained foam carbon loaded with Co nanowire precursor was washed three times with water and ethanol, and then dried overnight in an oven at 60°C.
[0064] The dried carbon foam loaded with cobalt nanowire precursors was placed in a tube furnace, and inert nitrogen gas was introduced, and the mixture was heated at 5°C for 1 minute. -1 The temperature was increased to 350℃ and held for 1 hour. The system was then cooled to room temperature to obtain the final product Co3O4-NW / CF.
[0065] Comparative Example 2
[0066] This comparative example prepares a similar NiO-NS / CF catalyst and compares it with that of Example 1.
[0067] 0.0967g Ni(NO3)2·6H2O and 0.06g CO(NH2)2 were added sequentially to 35mL of ethanol solution, and the solution was sonicated for 5 minutes to obtain a transparent light green solution B.
[0068] The size is 2×2cm 2 The foamed carbon was immersed in solution B, and then the system was transferred to a 50 mL hydrothermal reactor, heated to 90 °C and held for 10 h, and then the system was cooled to room temperature.
[0069] The obtained foam carbon loaded with Ni nanosheet precursor was washed three times with water and ethanol, and then dried overnight in an oven at 60°C.
[0070] The dried carbon foam loaded with Ni nanosheet precursors was placed in a tube furnace, and inert nitrogen gas was introduced, and the mixture was heated at 5°C for 1 minute. -1 The temperature was increased to 350℃ and held for 1 hour. The system was then cooled to room temperature to obtain the final product NiO-NS / CF.
[0071] The bifunctional electrocatalyst prepared in the above embodiments of the present invention consists of a core-shell structure (NiO@Co3O4) of transition metal oxide Co3O4 nanowires@NiO nanosheets supported on highly conductive three-dimensional self-supporting foam carbon. This catalyst material possesses abundant active sites and surface area. The synergistic effect between Co3O4 nanowires and NiO nanosheets, as well as the interaction between the NiO@Co3O4 core-shell structure and the three-dimensional foam carbon support, enable it to exhibit high catalytic activity in both hydrogen evolution and oxygen evolution electrocatalysis. The assembled water electrolysis cell also exhibits low overpotential and high stability. The three-dimensional self-supporting transition metal-based core-shell structure catalyst prepared in this invention provides a new technical approach for designing and synthesizing low-cost, high-activity bifunctional water electrolysis catalysts.
[0072] The present invention provides a bifunctional OER / HER water electrolysis catalyst and its application in the water electrolysis reaction. By combining the structure and components of the bifunctional OER / HER water electrolysis catalyst, it is composed of two transition metal oxides and a conductive support. Through solvothermal method and heat treatment, the composite metal oxides form a core-shell heterostructure, which is in situ supported on conductive three-dimensional foam carbon, so that it has the dual function of catalyzing oxygen evolution reaction and hydrogen evolution reaction in water electrolysis reaction. Specifically, it is a three-dimensional self-supporting NiO@Co3O4 / CF catalyst.
[0073] Through actual testing, the three-dimensional self-supporting NiO@Co3O4 / CF catalyst provided by this invention exhibits dual functionality in catalyzing both oxygen evolution and hydrogen evolution reactions during water electrolysis. Under alkaline conditions, both reactions achieve an amplification rate of 10 mA cm⁻¹. -2 The overpotentials required for the current densities are 195mV and 103mV, respectively. When used as cathode and anode in the same alkaline electrolytic cell for water electrolysis, only 1.53V is needed to achieve 10mA / cm. -2 It has a high current density and can operate stably for more than 42 hours.
[0074] It should be noted that, within the scope described above in this invention, other OER / HER bifunctional water electrolysis catalysts obtained by selecting other components, proportions, and preparation processes can all achieve the technical effects of this invention, and therefore will not be listed one by one.
[0075] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any person skilled in the art can make many possible variations or equivalent embodiments of the present invention within the scope of the present invention without departing from its scope. Therefore, all equivalent modifications made based on the structure, construction, and principles of the present invention without departing from its scope should be covered within the protection scope of the present invention.
Claims
1. A bifunctional OER / HER water electrolysis catalyst, characterized in that, It is a three-dimensional self-supporting transition metal-based OER / HER catalyst, which consists of two transition metal oxides and a conductive support. Through solvothermal method and heat treatment, the composite metal oxides are in-situ loaded on conductive three-dimensional foam carbon to form a three-dimensional self-supporting NiO-NS@Co3O4-NW / CF catalyst, abbreviated as NiO@Co3O4 / CF catalyst. This catalyst is a three-dimensional self-supporting hierarchical porous nanocomposite material NiO@Co3O4 / CF obtained by composite of transition metal-based oxides and core-shell structured NiO@Co3O4 with three-dimensional foam carbon as support. Among them, the core-shell structured NiO@Co3O4 is obtained by using Co3O4 as core and uniformly loading NiO nanosheets in-situ on Co3O4 to form a shell layer, which is then coated with Co3O4 nanowires to obtain the core-shell structured NiO@Co3O4. This core-shell structure is the active component in the catalyst.
2. The bifunctional OER / HER water electrolysis catalyst according to claim 1, characterized in that, The catalyst is composed of three-dimensional self-supporting foam carbon supported transition metal oxide Co3O4 nanowires@NiO nanosheets, wherein the Co3O4 core layer has a nanowire structure with a length of 3-5 μm and a diameter of 100-200 nm, and is uniformly distributed on the framework of the three-dimensional foam carbon support.
3. The bifunctional OER / HER water electrolysis catalyst according to claim 1, characterized in that, The NiO shell has a nanosheet morphology with an average size of 200-500 nm and a thickness of 10-50 nm.
4. A method for preparing a bifunctional OER / HER water electrolysis catalyst according to any one of claims 1 to 3, characterized in that, Includes the following steps: S1: Preparation of three-dimensional foam carbon carrier with melamine carbon foam: under the flow of 100 mL·min -1 nitrogen, melamine foam was heated to 700°C according to the temperature program and kept for 1 hour, and black three-dimensional foam carbon was obtained after cooling to room temperature; S2: Preparation of foam carbon supported on nickel@cobalt precursors: Dissolve appropriate amounts of cobalt salt, urea, and CTAB in water and sonicate for 5-10 minutes to obtain a transparent solution. Measure the size of the foam carbon (2×2 cm). 2 After the foamed carbon is immersed in the solution, it is transferred to the hydrothermal reactor for the first step of hydrothermal reaction to obtain foamed carbon loaded with cobalt precursor. After washing, it is immersed in an ethanol solution containing nickel salt and urea and transferred as a whole to the reactor for the second step of hydrothermal reaction. After cooling to room temperature, the foamed carbon loaded with nickel@cobalt precursor is washed to obtain the foamed carbon. S3: Catalyst preparation: Foamed carbon loaded with nickel@cobalt precursor was placed in a tube furnace and calcined at 350°C for 1 hour. After cooling to room temperature, NiO@Co3O4 / CF catalyst was obtained.
5. The preparation method according to claim 4, characterized in that, The cobalt salt in step S2 is Co(NO3)2·6H2O, and the nickel salt is Ni(NO3)2·6H2O.
6. The application of the bifunctional OER / HER water electrolysis catalyst according to any one of claims 1 to 3 in the water electrolysis reaction, wherein the bifunctional OER / HER water electrolysis catalyst has the dual function of catalyzing the oxygen evolution reaction and the hydrogen evolution reaction in the water electrolysis reaction.
7. The application according to claim 6, characterized in that, The catalyst is a three-dimensional self-supporting NiO@Co3O4 / CF catalyst, which achieves oxygen evolution reaction and hydrogen evolution reaction 10 mA cm⁻¹ under alkaline conditions. −2 The overpotentials required for the current densities are 195 mV and 103 mV, respectively.
8. The application according to claim 7, characterized in that, When the catalyst is used as both cathode and anode in the same alkaline electrolytic cell for water electrolysis, a 10 mA cm⁻¹ solution is obtained at a voltage of 1.53 V. −2 It has a high current density and can operate stably.