Preparation method of cobalt-based lattice strain oxygen evolution reaction catalyst
By combining gas-phase phosphating and electrochemical oxidation, the lattice strain of cobalt-based catalysts was controlled to form CoOOH nanosheets, which solved the problem of insufficient oxygen evolution reaction activity of cobalt-based catalysts in alkaline media and achieved highly efficient electrocatalytic water splitting and energy conversion.
Patent Information
- Application Number
- CN202411039122.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-31
- Publication Date
- 2025-10-28
- Estimated Expiration
- 2044-07-31
AI Technical Summary
In the prior art, cobalt-based catalysts have insufficient catalytic activity in the oxygen evolution reaction in alkaline media, and conventional lattice strain engineering is complex to operate and easily introduces unnecessary components, making it difficult to effectively control the electronic structure of the catalyst active sites.
By combining gas-phase phosphating and electrochemical oxidation, the lattice strain of the pre-catalyst CoP nanorods is modulated through the Kirkendall effect to form CoOOH nanosheets, thereby achieving in-situ reconstruction of the catalyst and regulating the electronic structure of the catalytic active sites.
It reduces the overpotential of the oxygen evolution reaction, improves the efficiency of hydrogen production from electrocatalytic water splitting, simplifies the operation process, and enhances the energy conversion efficiency of hydrogen production from water electrolysis by regulating the Co-O bond length and the valence state of active sites.
Smart Images
Figure CN118957634B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of oxygen evolution reaction catalyst preparation technology, specifically a method for preparing a cobalt-based lattice strain oxygen evolution reaction catalyst. Background Technology
[0002] Hydrogen is expected to replace fossil fuels as the carrier of future energy. In recent years, cobalt-based transition metal catalysts, such as oxides, nitrides, phosphides, sulfides, and selenides, have been widely reported as catalysts for the oxygen evolution reaction (OER) in alkaline media. However, in alkaline media, OER catalysts undergo phase reconstruction, and compared to directly synthesized hydroxyoxides, hydroxyoxides formed by in-situ reconstruction from pre-catalysts often exhibit stronger catalytic activity.
[0003] Lattice strain engineering, which induces changes in interatomic spacing, is a highly effective strategy for controlling the electronic structure and local coordination environment of catalyst active sites, and has remarkable potential to overcome the limitations of compositional adjustment. Conventional methods of induced strain include heat treatment, morphology design, core-shell structure, alloying, and doping. However, these methods require stringent experimental conditions, involve complex procedures, or often introduce unnecessary components, making practical experimental operations difficult. Therefore, developing new lattice strain-induced strategies to control the electronic structure of catalyst active sites has become a challenge in the development of advanced catalysts.
[0004] Therefore, it is necessary to design a cobalt-based catalyst with lattice strain to regulate the oxygen evolution reaction performance by the degree of strain, and to conduct in-depth research on the "structure-activity relationship" between material structure and catalytic activity. Summary of the Invention
[0005] The purpose of this invention is to provide a method for preparing a cobalt-based lattice strain oxygen evolution reaction catalyst to solve the problems in the prior art.
[0006] The objective of this invention can be achieved through the following technical solutions:
[0007] A method for preparing a cobalt-based lattice-strained oxygen evolution reaction catalyst, the method comprising the following steps:
[0008] S1. Weigh out the mixture of Co(NO3)2·6H2O and CO(NH2)2 dissolved in a beaker, and stir at room temperature to obtain solution A;
[0009] S2. Transfer solution A to a stainless steel reactor with a polytetrafluoroethylene liner, separate the intermediate product by vacuum filtration, and wash and dry to obtain solid powder B.
[0010] S3. After grinding the solid powder B obtained in S2, place it in a ceramic boat for annealing to obtain solid powder C;
[0011] S4. Weigh solid powders C and NaH2PO2·H2O separately and place them in different ceramic boats. Place the ceramic boats in a tube furnace for annealing to obtain the precatalyst CoPxNR.
[0012] S5. Weigh the precatalyst solid powder obtained in S4 and disperse it in the mixture in a centrifuge tube. Ultrasonicate at room temperature to obtain a precatalyst slurry. Take the slurry and drop it onto hydrophilic carbon paper and dry it.
[0013] S6. The pre-catalyst supported on carbon paper is oxidized for 10 hours, then washed and dried to obtain the oxygen evolution reaction catalyst CoOOHx NS supported on carbon paper.
[0014] Furthermore, the beaker mixture in S1 is a mixture of 15 mL of deionized water and 15 mL of anhydrous ethanol, and the stirring time is 10-15 min.
[0015] Further, the specific operation in S2 includes placing the reactor in an oven to carry out a hydrothermal reaction, maintaining it at 100°C for 10 hours, and after the reaction is completed and the reactor is naturally cooled to room temperature, the reactor is taken out to obtain a solid-liquid mixture, which is then washed with deionized water 3-5 times, and finally dried in a vacuum environment at 60°C for 8-12 hours to obtain solid powder B.
[0016] Furthermore, the grinding time in S3 is 5-10 min, and the annealing conditions in the tube furnace are: an air atmosphere at a temperature of 350℃ and an annealing time of 2 h.
[0017] Further, the specific operation in S4 is as follows: weigh 50mg of solid powder C and place it in the ceramic boat;
[0018] Weigh out 500-2000 mg of NaH2PO2·H2O and place it in the ceramic ark II;
[0019] Ceramic Ark 1 was placed downstream of the gas flow in a tube furnace, and Ceramic Ark 2 was placed upstream of the gas flow in a tube furnace, with a distance of 2-4 cm between them. The tube furnace was annealed for 2 hours under an argon atmosphere at 350°C to obtain the pre-catalyst CoPxNR, i.e., cobalt phosphide nanorods.
[0020] Further, the specific operation in S5 is as follows: weigh 5 mg of pre-catalyst solid powder and disperse it in a centrifuge tube in a mixture of 30 μL of Nafion solution, 250 μL of deionized water and 750 μL of anhydrous ethanol, and sonicate at room temperature for 1-2 h to obtain a pre-catalyst slurry.
[0021] Under infrared drying, use a pipette to take 200 μL of slurry in small, multiple applications and evenly drop it onto one side of the surface to a depth of 1 cm. 2 On hydrophilic carbon paper.
[0022] Further, the specific operation in S6 is as follows: using the prepared carbon paper with the pre-catalyst as the working electrode, the carbon rod as the counter electrode, Hg|HgO as the reference electrode, and 1M KOH as the electrolyte, a typical three-electrode system is formed. A 10 mA·cm⁻¹ electrochemical workstation is used to apply the electrolyte using a chronopotentiometric method. -2 The current was used to oxidize the pre-catalyst loaded on carbon paper for 10 hours;
[0023] The oxidized carbon paper was washed with deionized water 3-5 times and dried in a vacuum environment at 60℃ for 8-12 hours to obtain the oxygen evolution reaction catalyst CoOOHxNS, namely cobalt hydroxyl oxide nanosheets.
[0024] Furthermore, the raw material mass ratio required for preparing the cobalt-based lattice strain oxygen evolution reaction catalyst by the preparation method is as follows: 163.7-164 mg of Co(NO3)2·6H2O, 135-135.2 mg of CO(NH2)2, and 500-2000 mg of NaH2PO2·H2O.
[0025] The beneficial effects of this invention are:
[0026] 1. The preparation method of this invention regulates the lattice strain of the pre-catalyst CoP nanorods through the Kirkendall effect during the gas-phase phosphating process of the pre-catalyst. With the help of an electrochemical oxidation process under preferred conditions, the pre-catalyst is completely reconstructed into CoOOH nanosheets, which are the actual active material for the oxygen evolution reaction, thereby achieving the regulation of the lattice strain of the CoP nanorods on the CoOOH nanosheets. Compared with conventional lattice strain engineering that directly acts on hydroxyl oxides, the in-situ derivatization of the pre-catalyst can reduce the overpotential of the actual catalyst oxygen evolution reaction without introducing external components, promote the occurrence of the oxygen evolution reaction on the anode side of the electrocatalytic water splitting to produce hydrogen, and reduce the energy consumption of the energy conversion device.
[0027] 2. The preparation method of this invention is not only simple and easy to operate, but also adjusts the lattice strain degree and local coordination environment of the pre-catalyst by changing the amount of phosphorus source in the gas-phase phosphating process. The synthesized in-situ catalyst material derived from the lattice strain of the pre-catalyst has tunable Co-O bond length and Co active site valence state, which can regulate the electronic structure of Co active sites, thereby exhibiting different electrocatalytic oxygen evolution reaction performance and improving the energy conversion efficiency of water electrolysis to hydrogen production. Attached Figure Description
[0028] The invention will now be further described with reference to the accompanying drawings.
[0029] Figure 1 This is the XRD pattern of the lattice strain precatalyst of this invention;
[0030] Figure 2 This is a locally magnified XRD pattern of the lattice strain precatalyst of this invention;
[0031] Figure 3 This is the FT-EXAFS image of the lattice strain precatalyst of this invention;
[0032] Figure 4 This is a SEM image of the lattice strain precatalyst of this invention;
[0033] Figure 5 This is a TEM image of the lattice strain precatalyst of this invention;
[0034] Figure 6 This is a SEM image of the lattice strain catalyst derived in situ according to the present invention;
[0035] Figure 7 This is a TEM image of the lattice strain catalyst derived in situ according to the present invention;
[0036] Figure 8 This is the XANES diagram of the lattice strain catalyst derived in situ according to the present invention;
[0037] Figure 9 This is a fitting diagram of the valence state of lattice strain catalysis derived in situ according to the present invention;
[0038] Figure 10 This is the FT-EXAFS image of the lattice strain catalyst derived in situ according to this invention;
[0039] Figure 11 This is a performance diagram of the lattice strain catalyst derived in situ according to the present invention. Detailed Implementation
[0040] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0041] A method for preparing a cobalt-based lattice strain oxygen evolution reaction catalyst, wherein the raw materials required for the preparation of the cobalt-based lattice strain oxygen evolution reaction catalyst are as follows: cobalt nitrate hexahydrate Co(NO3)2·6H2O, urea CO(NH2)2, deionized water, anhydrous ethanol, sodium hypophosphite monohydrate NaH2PO2·H2O, and Nafion solution.
[0042] A method for preparing a cobalt-based lattice-strained oxygen evolution reaction catalyst, the method comprising the following steps:
[0043] S1. Take 15 mL of deionized water and 15 mL of anhydrous ethanol and mix them in a beaker. Weigh 163.7-164 mg of Co(NO3)2·6H2O and 135-135.2 mg of CO(NH2)2 and dissolve them in the mixture in the beaker. Stir at room temperature for 10-15 min to obtain solution A.
[0044] S2. Transfer solution A to a stainless steel reactor with a polytetrafluoroethylene liner. Then, place the reactor in an oven for hydrothermal reaction and maintain it at 100°C for 10 hours. After the reaction is completed and the mixture is naturally cooled to room temperature, remove the reactor to obtain a solid-liquid mixture. Separate the intermediate product by vacuum filtration and wash it with deionized water 3-5 times. Finally, dry it in a vacuum environment at 60°C for 8-12 hours to obtain solid powder B.
[0045] S3. After grinding the solid powder B obtained in S2 for 5-10 minutes, place it in a ceramic boat and anneal it in an air atmosphere at 350°C for 2 hours in a tube furnace to obtain solid powder C.
[0046] S4. Weigh 50 mg of the obtained solid powder C and place it in a ceramic ark.
[0047] Weigh out 500-2000 mg of NaH2PO2·H2O and place it in the ceramic ark II;
[0048] Ceramic Ark 1 was placed downstream of the gas flow in a tube furnace, and Ceramic Ark 2 was placed upstream of the gas flow in a tube furnace, with a distance of 2-4 cm between them. The tube furnace was annealed for 2 hours under an argon atmosphere at 350°C to obtain the pre-catalyst CoPxNR, i.e., cobalt phosphide nanorods.
[0049] S5. Weigh 5 mg of the precatalyst solid powder CoPx NR obtained in S4 and disperse it in a centrifuge tube containing a mixture of 30 μL Nafion solution, 250 μL deionized water and 750 μL anhydrous ethanol. Sonicate at room temperature for 1-2 h to obtain a precatalyst slurry.
[0050] Under infrared drying, use a pipette to take 200 μL of slurry in small, multiple applications and evenly drop it onto one side of the surface to a depth of 1 cm. 2 On hydrophilic carbon paper.
[0051] S6. In a typical three-electrode system, the carbon paper with the pre-catalyst prepared in S5 is used as the working electrode, the carbon rod is used as the counter electrode, Hg|HgO is used as the reference electrode, and 1M KOH is used as the electrolyte.
[0052] The electrochemical workstation applied 10 mA·cm using a chronopotentiometric method. -2 The current was used to oxidize the pre-catalyst loaded on carbon paper for 10 hours;
[0053] Finally, the oxidized carbon paper was washed with deionized water 3-5 times and dried in a vacuum environment at 60℃ for 8-12 hours to obtain the oxygen evolution reaction catalyst CoOOHxNS, i.e., cobalt hydroxyl oxide nanosheets, supported on the carbon paper.
[0054] Example 1
[0055] A method for preparing a cobalt-based lattice-strained oxygen evolution reaction catalyst, the method comprising the following steps:
[0056] S1. Take 15 mL of deionized water and 15 mL of anhydrous ethanol and mix them in a beaker. Weigh 163.7 mg of Co(NO3)2·6H2O and 135.2 mg of CO(NH2)2 and dissolve them in the mixture in the beaker. Stir at room temperature for 10 min to obtain solution A.
[0057] S2. Transfer solution A to a stainless steel reactor with a polytetrafluoroethylene liner. Then, place the reactor in an oven for hydrothermal reaction and maintain it at 100°C for 10 hours. After the reaction is completed and the mixture is naturally cooled to room temperature, remove the reactor to obtain a solid-liquid mixture. Separate the intermediate product by vacuum filtration and wash it three times with deionized water. Finally, dry it in a vacuum environment at 60°C for 8 hours to obtain solid powder B.
[0058] S3. After grinding the solid powder B obtained in S2 for 5 minutes, place it in a ceramic boat and anneal it in an air atmosphere at 350°C for 2 hours in a tube furnace to obtain solid powder C.
[0059] S4. Weigh 50 mg of the obtained solid powder C and place it in a ceramic ark.
[0060] Weigh out another 500 mg of NaH2PO2·H2O and place it in the ceramic ark II;
[0061] Ceramic Ark 1 was placed downstream of the gas flow in a tube furnace, and Ceramic Ark 2 was placed upstream of the gas flow in a tube furnace, with a distance of 2 cm between them. The tube furnace was annealed for 2 hours under an argon atmosphere at 350°C to obtain the pre-catalyst CoP10 NR, i.e., cobalt phosphide nanorods.
[0062] S5. Weigh 5 mg of the precatalyst solid powder CoP10NR obtained in S4 and disperse it in a centrifuge tube containing a mixture of 30 μL Nafion solution, 250 μL deionized water and 750 μL anhydrous ethanol. Sonicate at room temperature for 1 h to obtain a precatalyst slurry.
[0063] Under infrared drying, use a pipette to take 200 μL of slurry in small, multiple applications and evenly drop it onto one side of the surface to a depth of 1 cm. 2 On hydrophilic carbon paper.
[0064] S6. In a typical three-electrode system, the carbon paper with the pre-catalyst prepared in S5 is used as the working electrode, the carbon rod is used as the counter electrode, Hg|HgO is used as the reference electrode, and 1M KOH is used as the electrolyte.
[0065] The electrochemical workstation applied 10 mA·cm using a chronopotentiometric method. -2 The current was used to oxidize the pre-catalyst loaded on carbon paper for 10 hours;
[0066] Finally, the oxidized carbon paper was washed three times with deionized water and dried in a vacuum environment at 60°C for 8 hours to obtain the oxygen evolution reaction catalyst CoOOH10NS, i.e., cobalt hydroxyl oxide nanosheets, supported on the carbon paper.
[0067] Example 2
[0068] A method for preparing a cobalt-based lattice-strained oxygen evolution reaction catalyst, the method comprising the following steps:
[0069] S1. Take 15 mL of deionized water and 15 mL of anhydrous ethanol and mix them in a beaker. Weigh 163.8 mg of Co(NO3)2·6H2O and 135.1 mg of CO(NH2)2 and dissolve them in the mixture in the beaker. Stir at room temperature for 13 min to obtain solution A.
[0070] S2. Transfer solution A to a stainless steel reactor with a polytetrafluoroethylene liner. Then, place the reactor in an oven for hydrothermal reaction and maintain it at 100°C for 10 hours. After the reaction is completed and the mixture is naturally cooled to room temperature, remove the reactor to obtain a solid-liquid mixture. Separate the intermediate product by vacuum filtration and wash it four times with deionized water. Finally, dry it in a vacuum environment at 60°C for 10 hours to obtain solid powder B.
[0071] S3. After grinding the solid powder B obtained in S2 for 7 minutes, place it in a ceramic boat and anneal it in an air atmosphere at 350°C for 2 hours in a tube furnace to obtain solid powder C.
[0072] S4. Weigh 50 mg of the obtained solid powder C and place it in a ceramic ark.
[0073] Weigh out another 1000 mg of NaH2PO2·H2O and place it in the ceramic ark II;
[0074] Ceramic Ark 1 was placed downstream of the gas flow in a tube furnace, and Ceramic Ark 2 was placed upstream of the gas flow in a tube furnace, with a distance of 3 cm between them. The tube furnace was annealed for 2 hours under an argon atmosphere at 350°C to obtain the pre-catalyst CoP20 NR, i.e., cobalt phosphide nanorods.
[0075] S5. Weigh 5 mg of the precatalyst solid powder CoP20NR obtained in S4 and disperse it in a centrifuge tube containing a mixture of 30 μL Nafion solution, 250 μL deionized water and 750 μL anhydrous ethanol. Sonicate at room temperature for 1.5 h to obtain a precatalyst slurry.
[0076] Under infrared drying, use a pipette to take 200 μL of slurry in small, multiple applications and evenly drop it onto one side of the surface to a depth of 1 cm. 2 On hydrophilic carbon paper.
[0077] S6. In a typical three-electrode system, the carbon paper with the pre-catalyst prepared in S5 is used as the working electrode, the carbon rod is used as the counter electrode, Hg|HgO is used as the reference electrode, and 1M KOH is used as the electrolyte.
[0078] The electrochemical workstation applied 10 mA·cm using a chronopotentiometric method. -2 The current was used to oxidize the pre-catalyst loaded on carbon paper for 10 hours;
[0079] Finally, the oxidized carbon paper was washed four times with deionized water and dried in a vacuum environment at 60°C for 10 hours to obtain the oxygen evolution reaction catalyst CoOOH20NS, i.e., cobalt hydroxyl oxide nanosheets, supported on the carbon paper.
[0080] Example 3
[0081] A method for preparing a cobalt-based lattice-strained oxygen evolution reaction catalyst, the method comprising the following steps:
[0082] S1. Take 15 mL of deionized water and 15 mL of anhydrous ethanol and mix them in a beaker. Weigh 164 mg of Co(NO3)2·6H2O and 135 mg of CO(NH2)2 and dissolve them in the mixture in the beaker. Stir at room temperature for 15 min to obtain solution A.
[0083] S2. Transfer solution A to a stainless steel reactor with a polytetrafluoroethylene liner. Then, place the reactor in an oven for hydrothermal reaction and maintain it at 100°C for 10 hours. After the reaction is completed and the mixture is naturally cooled to room temperature, remove the reactor to obtain a solid-liquid mixture. Separate the intermediate product by vacuum filtration and wash it 5 times with deionized water. Finally, dry it in a vacuum environment at 60°C for 12 hours to obtain solid powder B.
[0084] S3. After grinding the solid powder B obtained in S2 for 10 min, place it in a ceramic boat and anneal it in an air atmosphere at 350℃ for 2 h in a tube furnace to obtain solid powder C.
[0085] S4. Weigh 50 mg of the obtained solid powder C and place it in a ceramic ark.
[0086] Weigh out another 2000 mg of NaH2PO2·H2O and place it in the ceramic ark II;
[0087] Ceramic Ark 1 was placed downstream of the gas flow in a tube furnace, and Ceramic Ark 2 was placed upstream of the gas flow in a tube furnace, with a distance of 4 cm between them. The tube furnace was annealed for 2 hours under an argon atmosphere at 350°C to obtain the pre-catalyst CoP40 NR, i.e., cobalt phosphide nanorods.
[0088] S5. Weigh 5 mg of the precatalyst solid powder CoP40 NR obtained in S4 and disperse it in a centrifuge tube containing a mixture of 30 μL Nafion solution, 250 μL deionized water and 750 μL anhydrous ethanol. Sonicate at room temperature for 2 h to obtain a precatalyst slurry.
[0089] Under infrared drying, use a pipette to take 200 μL of slurry in small, multiple applications and evenly drop it onto one side of the surface to a depth of 1 cm. 2 On hydrophilic carbon paper.
[0090] S6. In a typical three-electrode system, the carbon paper with the pre-catalyst prepared in S5 is used as the working electrode, the carbon rod is used as the counter electrode, Hg|HgO is used as the reference electrode, and 1M KOH is used as the electrolyte.
[0091] The electrochemical workstation applied 10 mA·cm using a chronopotentiometric method. -2 The current was used to oxidize the pre-catalyst loaded on carbon paper for 10 hours;
[0092] Finally, the oxidized carbon paper was washed five times with deionized water and dried in a vacuum environment at 60°C for 12 hours to obtain the oxygen evolution reaction catalyst CoOOH40 NS, i.e., cobalt hydroxyl oxide nanosheets, which are supported on the carbon paper.
[0093] The performance of the in-situ derived lattice-strained oxygen evolution reaction catalyst was tested, and the test data are as follows:
[0094] like Figure 1-3 As shown, the XRD and Co K-edge FT-XAFS images of the precatalyst CoP nanorods prepared by the gas-phase phosphating process indicate that the tube furnace gas-phase phosphating can prepare precatalysts with a defined phase, and the lattice strain degree and local coordination environment of the precatalyst can be controlled by changing the amount of phosphorus source.
[0095] like Figure 4 , Figure 5 As shown, SEM and TEM images of the precatalyst CoP nanorods prepared by the gas-phase phosphating process reveal that the precatalyst has a rod-like morphology and contains circular cavities, indicating that the gas-phase phosphating process is affected by the Kirkendall effect.
[0096] like Figure 6 , Figure 7 As shown, SEM and TEM images of the CoOOH nanosheets, which are oxygen evolution reaction catalysts formed by electrochemical oxidation reconstruction of the precatalyst, reveal that the hydroxyl oxides derived in situ from the precatalyst have a regular hexagonal morphology.
[0097] like Figure 8-10 As shown, XANES, valence state fitting and FT-EXAFS plots of CoOOH nanosheets Co K-edges formed by electrochemical oxidation reconstruction of the precatalyst reveal that the in-situ derived hydroxy oxides of the precatalyst with different lattice strains have different local coordination environments and valence states of metal active sites.
[0098] like Figure 11 As shown, the oxygen evolution reaction (OER) performance of catalysts with different lattice strains was tested using a typical three-electrode system. It was found that CoOOH20NS, with the longest Co-O bond length and higher valence state of the Co active site, exhibited the best OER performance, showing the lowest reaction potential in 1M KOH solution, and continuously driving a 10 mA cm⁻¹ electrode for up to 10 h. -2 Oxygen evolution reaction at current density.
[0099] Compared with related technologies, the cobalt-based lattice strain oxygen evolution reaction catalyst preparation method provided by the present invention has the following beneficial effects:
[0100] I. By controlling the lattice strain of the precatalyst CoP nanorods during the gas-phase phosphating process of the precatalyst through the Kirkendall effect, and by using an electrochemical oxidation process under optimized conditions, the precatalyst is completely reconstructed into CoOOH nanosheets, which are the real active material for the oxygen evolution reaction, so as to achieve the control of the lattice strain of the catalyst CoOOH nanosheets by the precatalyst CoP nanorods.
[0101] Compared to conventional lattice strain engineering that directly acts on hydroxyl oxides, in-situ derivatization of pre-catalysts can reduce the overpotential of the actual catalyst oxygen evolution reaction without introducing foreign components, promote the occurrence of oxygen evolution reaction on the anode side of electrocatalytic water splitting to produce hydrogen, and reduce the energy consumption of the energy conversion device.
[0102] Second, its preparation process is not only simple and easy to operate, but also adjusts the lattice strain degree and local coordination environment of the pre-catalyst by changing the amount of phosphorus source in the gas phase phosphating process. The synthesized in-situ catalyst material derived from the lattice strain of the pre-catalyst has tunable Co-O bond length and Co active site valence state, which can regulate the electronic structure of Co active sites, thereby exhibiting different electrocatalytic oxygen evolution reaction performance and improving the energy conversion efficiency of water electrolysis to hydrogen production.
[0103] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.
Claims
1. A method for preparing a cobalt-based lattice-strained oxygen evolution reaction catalyst, characterized in that, The preparation method includes the following steps: S1. Weigh out the mixture of Co(NO3)2·6H2O and CO(NH2)2 dissolved in a beaker, and stir at room temperature to obtain solution A; S2. Transfer solution A to a stainless steel reactor with a polytetrafluoroethylene liner. Place the reactor in an oven for hydrothermal reaction and maintain it at 100°C for 10 hours. After the reaction is completed and the mixture is naturally cooled to room temperature, remove the reactor to obtain a solid-liquid mixture. Separate the intermediate product by vacuum filtration and wash it with deionized water 3-5 times. Finally, dry it in a vacuum environment at 60°C for 8-12 hours to obtain solid powder B. S3. After grinding the solid powder B obtained in S2, place it in a ceramic boat for annealing to obtain solid powder C; S4. Weigh solid powders C and NaH2PO2·H2O separately and place them in different ceramic boats. Anneal the ceramic boats in a tube furnace to obtain the pre-catalyst CoP. x NR; S5. Weigh the precatalyst solid powder obtained in S4 and disperse it in the mixture in a centrifuge tube. Ultrasonicate at room temperature to obtain a precatalyst slurry. Take the slurry and drop it onto hydrophilic carbon paper and dry it. S6. Using the prepared carbon paper with the pre-catalyst as the working electrode, a carbon rod as the counter electrode, Hg|HgO as the reference electrode, and 1M KOH as the electrolyte, a typical three-electrode system was formed. A current of 10 mA·cm⁻² was applied using a chronopotential method on an electrochemical workstation to oxidize the pre-catalyst on the carbon paper for 10 h. After washing and drying, the oxygen evolution reaction catalyst CoOOH on the carbon paper was obtained. x NS; The mixed solution in the beaker in S1 is a mixture of 15 mL of deionized water and 15 mL of anhydrous ethanol, and the stirring time is 10-15 min.
2. The method for preparing a cobalt-based lattice-strained oxygen evolution reaction catalyst according to claim 1, characterized in that, The grinding time in S3 is 5-10 min, and the annealing conditions in the tube furnace are: air atmosphere at 350°C and annealing time of 2 h.
3. The method for preparing a cobalt-based lattice-strained oxygen evolution reaction catalyst according to claim 1, characterized in that, The specific operation in S4 is as follows: Weigh 50mg of solid powder C and place it in ceramic boat one; Weigh out 500-2000 mg of NaH2PO2·H2O and place it in the ceramic ark II; Ceramic boat one was placed downstream of the gas flow in a tube furnace, and ceramic boat two was placed upstream of the gas flow, with a distance of 2-4 cm between them. Annealing was performed in the tube furnace at 350°C under an argon atmosphere for 2 hours to obtain the pre-catalyst CoP. x NR stands for cobalt phosphide nanorods.
4. The method for preparing a cobalt-based lattice-strained oxygen evolution reaction catalyst according to claim 3, characterized in that, The specific operation in S5 is as follows: Weigh 5 mg of pre-catalyst solid powder and disperse it in a centrifuge tube in a mixture of 30 μL of Nafion solution, 250 μL of deionized water and 750 μL of anhydrous ethanol, and sonicate at room temperature for 1-2 hours to obtain a pre-catalyst slurry. Under infrared drying, 200 μL of slurry was taken in small amounts and repeatedly and evenly dripped onto a 1 cm² hydrophilic carbon paper using a pipette.
5. The method for preparing a cobalt-based lattice-strained oxygen evolution reaction catalyst according to claim 4, characterized in that, The specific operation in S6 is as follows: the oxidized carbon paper is washed with deionized water 3-5 times, and dried in a vacuum environment at 60°C for 8-12 hours to obtain the oxygen evolution reaction catalyst CoOOH on the carbon paper. x NS stands for cobalt hydroxyoxide nanosheets.
6. The method for preparing a cobalt-based lattice-strained oxygen evolution reaction catalyst according to claim 1, characterized in that, The preparation method requires the following raw material mass ratios for preparing the cobalt-based lattice strain oxygen evolution reaction catalyst: 163.7-164 mg of Co(NO3)2·6H2O, 135-135.2 mg of CO(NH2)2, and 500-2000 mg of NaH2PO2·H2O.