Ferrocobalt bimetallic hydrogen evolution catalyst and preparation method and application thereof
By synthesizing Fe@Co-ZIF precursor materials at room temperature and then performing nitrogen doping and high-temperature annealing, a cobalt-iron bimetallic catalyst was prepared, solving the problems of high cost and complex process of water electrolysis hydrogen production catalysts, and achieving low-cost and high-efficiency water electrolysis hydrogen evolution effect.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA PETROLEUM & CHEMICAL CORP
- Filing Date
- 2024-11-11
- Publication Date
- 2026-05-12
AI Technical Summary
Existing catalysts for hydrogen production via water electrolysis are expensive to produce and have complex preparation processes, which limits their development and application in water electrolysis hydrogen production technology.
A non-noble metal cobalt-iron bimetallic catalyst was prepared by synthesizing Fe@Co-ZIF precursor material in a one-step process at room temperature. Fe element was dispersed in the cavity of Co-ZIF material in a free state. Combined with nitrogen doping and high-temperature annealing treatment, the catalyst structure and component ratio were optimized to improve catalytic activity and stability.
The catalyst has achieved low-cost, large-scale production, exhibiting good catalytic activity and cycle stability, excellent hydrogen evolution performance, low overpotential, small decay rate, and low Tafel slope, demonstrating highly efficient hydrogen evolution performance in water electrolysis.
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Figure CN122013227A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of water electrolysis for hydrogen production technology, and more specifically, to a cobalt-iron bimetallic hydrogen evolution catalyst, its preparation method, and its application. Background Technology
[0002] Developing new clean energy sources has become a powerful solution to effectively achieve the above goals. Hydrogen energy, with its characteristics of light weight, high energy density, high calorific value, and environmental friendliness, is a highly promising green energy carrier in the new round of energy revolution. With the advancement of science and technology, various methods for producing hydrogen have been developed. Among them, the water electrolysis method uses water as raw material, produces no pollutants during the electrolysis process, and has a relatively simple production process. Therefore, it is considered an efficient, environmentally friendly, and sustainable hydrogen production technology with broad application prospects.
[0003] Noble metal materials such as Pt / C, RuO2, and IrO2 have demonstrated excellent performance in the field of water electrolysis for hydrogen production, but their high cost limits the industrialization of this technology. Therefore, developing highly active and stable non-precious metal catalysts is essential for the development of this field.
[0004] Bimetallic active sites can enhance catalytic performance through synergistic electron transfer and transport. Furthermore, the content, particle size, and structure of the active components all influence the intrinsic activity of the catalyst. Currently, the synthesis process of ZIF-based Co-Fe bimetallic catalysts is complex, and the Fe component is mostly coated on the surface of Co-ZIF materials as particulate matter, limiting the interaction between the bimetallic sites. Summary of the Invention
[0005] To address the problems existing in current technologies, most water electrolysis hydrogen evolution catalysts currently have high production costs and complex preparation processes, limiting their development and application. This invention provides a cobalt-iron bimetallic hydrogen evolution catalyst, its preparation method, and its application. This invention synthesizes Fe@Co-ZIF precursor materials in a one-step process at room temperature, improving the complex preparation conditions that require high-temperature heating, thus facilitating large-scale production. This invention prepares a non-precious bimetallic catalyst through a simple and feasible synthesis process, effectively reducing production costs. Simultaneously, this catalyst exhibits good catalytic activity and cycling stability.
[0006] One of the objectives of this invention is to provide a cobalt-iron bimetallic hydrogen evolution catalyst.
[0007] The cobalt-iron bimetallic hydrogen evolution catalyst of the present invention comprises:
[0008] Co-ZIF material and Fe element freely dispersed in the cavity of the Co-ZIF material;
[0009] Based on a total catalyst weight of 100%,
[0010] The catalyst contains 32%-50% Co by weight.
[0011] The catalyst contains 1%-12% Fe by weight.
[0012] The type, number, morphology, and particle size of active sites on a catalyst determine its catalytic performance. In the Co-Fe bimetallic catalyst of this invention, Fe exists in a free state, and the Co and Fe bimetals, through synergistic action, can promote the kinetics of the hydrogen evolution reaction in water electrolysis, thereby improving the catalyst's hydrogen evolution performance.
[0013] In a preferred embodiment of the present invention:
[0014] The catalyst contains 37%-45% Co by weight; and / or,
[0015] The catalyst contains 3%-7% Fe by weight.
[0016] In a preferred embodiment of the present invention:
[0017] The Co-ZIF material is a nitrogen-doped Co-ZIF material; preferably,
[0018] The nitrogen-doped Co-ZIF material contains 3.8%-4.8% nitrogen by weight, more preferably 4.1%-4.6%.
[0019] In a preferred embodiment of the present invention:
[0020] The catalyst has a particle size range of 100-500 nm, preferably 180-350 nm.
[0021] A second objective of this invention is to provide a method for preparing a cobalt-iron bimetallic hydrogen evolution catalyst as described in one objective of this invention.
[0022] The preparation method of the cobalt-iron bimetallic hydrogen evolution catalyst of the present invention includes:
[0023] The catalyst was prepared by mixing a cobalt-containing compound dissolved in solvent A and ferric chloride with 2-methylimidazole dissolved in solvent B, stirring and reacting, and then centrifuging and washing.
[0024] In a preferred embodiment of the present invention, the method further includes:
[0025] The catalyst was mixed with a nitrogen-containing compound and then annealed at high temperature under a protective gas atmosphere.
[0026] This invention uses cobalt atoms as metal nodes to coordinate with nitrogen atoms in the organic ligand dimethylimidazole, forming a Co-based ZIF material. Ferric chloride is dispersed in a free state within the cavities of the ZIF material, resulting in a Co-based ZIF material coated with iron. This material is then co-annealed with nitrogen-containing melamine at high temperature under specific conditions to obtain a C / N-doped CoFe bimetallic catalyst for hydrogen evolution in water electrolysis.
[0027] The following solutions can be adopted:
[0028] Preparation of Fe@Co-ZIF materials: Cobalt nitrate hexahydrate and ferric chloride were weighed into a beaker, and then solvent A was added and stirred to dissolve them, obtaining solution A. 2-Methylimidazole was weighed and dissolved in a beaker containing solvent B, and stirred to obtain solution B. Subsequently, under stirring conditions, solution B was added to solution A and mixed thoroughly. The reaction was carried out at room temperature under stirring conditions, centrifuged, and the product was washed three times with anhydrous ethanol to obtain Fe@Co-ZIF nanomaterials, which were then dried for later use.
[0029] Preparation of CoFe-C / N catalyst: Weigh dry Fe@Co-ZIF nanomaterials and melamine, and mix them thoroughly. Under an argon atmosphere, slowly heat to 700-900℃ and maintain at this temperature for 1-8 hours, then allow to cool naturally to room temperature to obtain CoFe-C / N powder catalyst.
[0030] In a preferred embodiment of the present invention:
[0031] The weight ratio of the cobalt-containing compound, ferric chloride, and 2-methylimidazole is 1:(0.01-0.5):(1-10), preferably 1:(0.05-0.3):(2-5); and / or,
[0032] The concentration of the cobalt-containing compound dissolved in solvent A is 0.01-0.2 mol / L, preferably 0.02-0.06 mol / L; and / or,
[0033] The concentration of the 2-methylimidazole dissolved in solvent B is 0.1-1.6 mol / L, preferably 0.2-0.8 mol / L.
[0034] In a preferred embodiment of the present invention:
[0035] The weight ratio of the catalyst to the nitrogen-containing compound is 1:(0.1-2), preferably 1:(0.3-1).
[0036] In a preferred embodiment of the present invention:
[0037] Solvent A is methanol and / or ethanol, preferably methanol; and / or,
[0038] The cobalt-containing compound is cobalt nitrate hexahydrate and / or cobalt chloride hexahydrate; and / or,
[0039] The solvent B is methanol and / or ethanol, preferably methanol.
[0040] In a preferred embodiment of the present invention:
[0041] The nitrogen-containing compound is melamine and / or urea, preferably melamine; and / or,
[0042] The protective gas is argon and / or nitrogen, preferably argon, which is safer than the H2 / Ar gas commonly used in the prior art.
[0043] In a preferred embodiment of the present invention:
[0044] The reaction temperature of the stirring reaction is 10℃-35℃ (room temperature), preferably 20℃-30℃, and / or the reaction time is 8-72 hours, preferably 16-36 hours, and / or the stirring speed is 6000-2000 rpm, preferably 1000-1600 rpm.
[0045] In a preferred embodiment of the present invention:
[0046] The high-temperature annealing is performed at a temperature of 700℃-900℃, preferably 760℃-840℃, and / or at a heating rate of 1-10℃ / min, preferably 3-5℃ / min, and / or at a annealing time of 1-8h, preferably 3-5h.
[0047] The second objective of this invention is to provide an application of a cobalt-iron bimetallic hydrogen evolution catalyst as described in the first objective of this invention, or a cobalt-iron bimetallic hydrogen evolution catalyst prepared by the method described in the second objective of this invention, in the field of hydrogen production by water electrolysis.
[0048] This invention synthesizes a Fe@Co-ZIF catalyst in a one-step process at room temperature, improving upon the complex and high-temperature-required preparation conditions of such materials and facilitating large-scale production. By modifying the reaction conditions, the presence of Co and Fe elements in the catalyst structure is controlled. Adding Fe during precursor synthesis promotes the uniform dispersion of Fe in a free state within the catalyst cavities, thereby enhancing the catalyst's catalytic activity. The free presence of Fe within the Co-ZIF framework facilitates the hydrogen evolution reaction during water electrolysis, resulting in excellent hydrogen evolution activity for this Co / Fe bimetallic catalyst. The introduction of nitrogen-containing compounds increases the nitrogen content of the catalyst, modulating the electron conduction pathway during water electrolysis and effectively enhancing the conductivity of the Co / Fe bimetallic hydrogen evolution catalyst. High-temperature calcination enhances the catalyst's cycle stability. Furthermore, the synergistic effect of the bimetallic active sites improves the hydrogen evolution activity during water electrolysis, promoting electron transfer and resulting in excellent hydrogen evolution performance for the CoFe-C / N catalyst. Under 1M KOH conditions, the current density can reach 10 mA / cm². 2 At that time, the hydrogen evolution overpotential of the working electrode can reach 177mV, the decay rate can reach 1.58% after 12 hours, and the Tafel slope can reach 98mV / dec. Attached Figure Description
[0049] Figure 1 The image shows a SEM image of the Fe@Co-ZIF catalyst prepared in Example 1.
[0050] Figure 2 SEM image of the CoFe-C / N catalyst prepared in Example 1;
[0051] Figure 3 Here is a SEM image of the Co-ZIF nanomaterials prepared in Comparative Example 2;
[0052] Figure 4 Here is a SEM image of the Fe@Co-ZIF nanomaterials prepared in Comparative Example 2;
[0053] Depend on Figure 3 and Figure 4 The comparison shows that the morphology of the Co-ZIF nanomaterials changed significantly after the Fe component was added, indicating that the Fe component in the Fe@Co-ZIF catalyst of Comparative Example 2 was aggregated on the Co-ZIF material and did not exist in the pores of the Co-ZIF framework in a free state.
[0054] Figure 5 The image shows the XRD pattern of the Fe@Co-ZIF catalyst prepared in Example 1.
[0055] Figure 6The XRD pattern of the Co-ZIF nanomaterials prepared in Comparative Example 1 is shown.
[0056] Depend on Figure 5 and Figure 6 The comparison shows that the catalyst framework structure remained intact after the addition of Fe element in Example 1. Combined with elemental analysis, it can be seen that the ferric chloride component exists in a free state in the pores of the framework structure.
[0057] Figure 7 The hydrogen evolution overpotential test results of the Fe@Co-ZIF catalyst prepared in Example 1 are shown in Figure 1.
[0058] Figure 8 The decay rate results of the Fe@Co-ZIF catalyst prepared in Example 1 are shown in the figure.
[0059] Figure 9 Tafel data of the Fe@Co-ZIF catalyst prepared in Example 1. Detailed Implementation
[0060] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.
[0061] The raw materials used in the embodiments and comparative examples of this invention are all conventional commercially available products.
[0062]
Example 1
[0063] (1) Weigh 3g of cobalt nitrate hexahydrate and 0.42g of ferric chloride into a 1L beaker, then add 0.3L of methanol solution and stir to dissolve, obtaining solution A. Weigh 10.15g of 2-methylimidazole and add it to a beaker containing 0.3L of methanol solution, stirring to obtain solution B. Then, under stirring, add solution B to solution A and mix thoroughly. Stir the above solutions at room temperature for 24h, centrifuge, and wash the product three times with anhydrous ethanol to obtain the Fe@Co-ZIF catalyst, which is then dried for later use. The scanning electron microscope image of the Fe@Co-ZIF catalyst is shown below. Figure 1 As shown, the particle size is in the range of 150-200 nm.
[0064] (2) Weigh 1g of the above-mentioned dried Fe@Co-ZIF catalyst and 0.5g of melamine, and mix them thoroughly. Continuously purge with argon gas for about 2 hours to completely remove any remaining gases from the system. Then, under an argon atmosphere, slowly heat to 800℃ at a heating rate of 5℃ / min, maintain this temperature for 4 hours, and allow to cool naturally to room temperature to obtain the powdered CoFe-C / N catalyst. The scanning electron microscope image of the CoFe-C / N catalyst is shown below. Figure 2 As shown in Table 1, the contents of nitrogen, Co, and Fe in the CoFe-C / N catalyst are shown in Table 2, and the particle size is shown in Table 3.
[0065]
Example 2
[0066] The method of Example 1 was followed, except that the ratio of cobalt nitrate hexahydrate and ferric chloride was changed. In step (1), 3g of cobalt nitrate hexahydrate and 0.84g of ferric chloride were weighed into a 1L beaker, and then 0.3L of methanol solution was added and stirred to dissolve them, thus obtaining solution A.
[0067] The contents of nitrogen, Co and Fe in the CoFe-C / N catalyst are shown in Table 1, and the particle size is shown in Table 2.
[0068]
Example 3
[0069] The procedure was carried out according to Example 1, except that the ratio of cobalt nitrate hexahydrate and ferric chloride was changed. In step (1), 3g of cobalt nitrate hexahydrate and 0.24g of ferric chloride were weighed into a 1L beaker, and then 0.3L of methanol solution was added and stirred to dissolve them, resulting in solution A.
[0070] The contents of nitrogen, Co and Fe in the CoFe-C / N catalyst are shown in Table 1, and the particle size is shown in Table 2.
[0071]
Example 4
[0072] The method of Example 1 was followed, except that in step (2), under the condition of continuous argon gas supply, the temperature was slowly heated to 700°C at a heating rate of 5°C / min and maintained at this temperature for 4 hours.
[0073] The contents of nitrogen, Co and Fe in the CoFe-C / N catalyst are shown in Table 1, and the particle size is shown in Table 2.
[0074]
Example 5
[0075] The method of Example 1 was followed, except that in step (2), under the condition of continuous argon gas supply, the temperature was slowly heated to 900°C at a heating rate of 5°C / min and maintained at that temperature for 4 hours.
[0076] The contents of nitrogen, Co and Fe in the CoFe-C / N catalyst are shown in Table 1, and the particle size is shown in Table 2.
[0077]
Example 6
[0078] The method of Example 1 was followed, except that in step (1), 2.5g of cobalt chloride hexahydrate and 0.24g of ferric chloride were weighed into a 1L beaker, and then 0.3L of methanol solution was added and stirred to dissolve them to obtain solution A.
[0079] The contents of nitrogen, Co and Fe in the CoFe-C / N catalyst are shown in Table 1, and the particle size is shown in Table 2.
[0080]
Example 7
[0081] The method was carried out according to Example 1, except that the ratio of cobalt nitrate hexahydrate and ferric chloride was changed. In step (1), 1.2 g of cobalt nitrate hexahydrate and 0.42 g of ferric chloride were weighed into a 1 L beaker, and then 0.3 L of methanol solution was added and stirred to dissolve them, thus obtaining solution A.
[0082] The contents of nitrogen, Co and Fe in the CoFe-C / N catalyst are shown in Table 1, and the particle size is shown in Table 2.
[0083]
Example 8
[0084] The method was carried out according to Example 1, except that the ratio of cobalt nitrate hexahydrate and ferric chloride was changed. In step (1), 10g of cobalt nitrate hexahydrate and 0.42g of ferric chloride were weighed into a 1L beaker, and then 0.3L of methanol solution was added and stirred to dissolve them, thus obtaining solution A.
[0085] The contents of nitrogen, Co and Fe in the CoFe-C / N catalyst are shown in Table 1, and the particle size is shown in Table 2.
[0086]
Example 9
[0087] The method was carried out according to Example 1, except that in step (1), 3.5g of 2-methylimidazole was weighed and added to a beaker containing 0.3L of methanol solution, and stirred to obtain solution B.
[0088] The contents of nitrogen, Co and Fe in the CoFe-C / N catalyst are shown in Table 1, and the particle size is shown in Table 2.
[0089]
Example 10
[0090] The method of Example 1 was followed, except that in step (1), 30g of 2-methylimidazole was weighed and added to a beaker containing 0.3L of methanol solution, and stirred to obtain solution B.
[0091] The contents of nitrogen, Co and Fe in the CoFe-C / N catalyst are shown in Table 1, and the particle size is shown in Table 2.
[0092]
Example 11
[0093] The method of Example 1 was followed, except that in step (2), 1g of the above-mentioned dried Fe@Co-ZIF catalyst was weighed, and 0.2g of melamine was weighed and mixed thoroughly.
[0094] The contents of nitrogen, Co and Fe in the CoFe-C / N catalyst are shown in Table 1, and the particle size is shown in Table 2.
[0095]
Example 12
[0096] The method of Example 1 was followed, except that in step (2), 1g of the above-mentioned dried Fe@Co-ZIF catalyst was weighed, and 2g of melamine was weighed, and the two were mixed thoroughly.
[0097] The contents of nitrogen, Co and Fe in the CoFe-C / N catalyst are shown in Table 1, and the particle size is shown in Table 2.
[0098] Comparative Example 1
[0099] The method was followed according to Example 1, except that in step (1), the reaction raw materials were only cobalt nitrate hexahydrate and 2-methylimidazole, without the addition of ferric chloride. Specifically, 3g of cobalt nitrate hexahydrate was weighed into a 1L beaker, followed by the addition of 0.3L of methanol solution, and stirred to dissolve, yielding solution A. 10.15g of 2-methylimidazole was weighed and added to a beaker containing 0.3L of methanol solution, and stirred to obtain solution B. Subsequently, under stirring conditions, solution B was added to solution A and mixed thoroughly. The above solutions were stirred at room temperature for 24 hours, centrifuged, and the product was washed three times with anhydrous ethanol to obtain Co-ZIF nanomaterials, which were then dried for later use.
[0100] Step (2) is the same as in Example 1. The nitrogen and Co content in the Co-C / N catalyst is shown in Table 1, and the particle size is shown in Table 2.
[0101] Comparative Example 2
[0102] 3g of cobalt nitrate hexahydrate was weighed and added to 0.3L of methanol solution, stirred until dissolved, to obtain solution A. 10.15g of 2-methylimidazole was weighed and added to a beaker containing 0.3L of methanol solution, stirred to obtain solution B. Then, under stirring, solution B was added to solution A and mixed thoroughly. The above solutions were stirred at room temperature for 24 hours, centrifuged, and the product was washed three times with anhydrous ethanol to obtain Co-ZIF nanomaterials, which were then dried for later use. Scanning electron microscopy of the Co-ZIF nanomaterials is shown below. Figure 3 As shown.
[0103] The dried Co-ZIF nanomaterials were dispersed in a mixed solution of ethanol and n-hexane (50 mL each) to obtain suspension C. 0.5 g of ferric chloride was weighed and dissolved in 10 mL of water to obtain solution D. Solution D was added to suspension C, stirred at room temperature for 4 hours, and washed twice each with deionized water and anhydrous ethanol to obtain Fe@Co-ZIF nanomaterials, which were then dried for later use. Scanning electron microscopy of the Fe@Co-ZIF nanomaterials is shown below. Figure 4 As shown.
[0104] Weigh 1g of the dried Fe@Co-ZIF nanomaterials and 0.5g of melamine, and mix them thoroughly. Continuously purge with argon gas for approximately 2 hours to completely remove any remaining gases from the system. Then, under argon atmosphere, slowly heat to 800℃ at a heating rate of 5℃ / min and maintain this temperature for 4 hours. Allow to cool naturally to room temperature to obtain a powdered CoFe-C / N catalyst. The nitrogen, Co, and Fe content of the CoFe-C / N catalyst is shown in Table 1, and the particle size is shown in Table 2.
[0105] Comparative Example 3
[0106] The method of Example 1 was followed, except that in step (2), under the condition of continuous argon gas supply, the temperature was slowly heated to 500°C at a heating rate of 5°C / min and maintained at that temperature for 4 hours.
[0107] The contents of nitrogen, Co and Fe in the CoFe-C / N catalyst are shown in Table 1, and the particle size is shown in Table 2.
[0108] Comparative Example 4
[0109] The method of Example 1 was followed, except that in step (2), under the condition of continuous argon gas supply, the temperature was slowly heated to 1000°C at a heating rate of 5°C / min and maintained at that temperature for 6 hours.
[0110] The contents of nitrogen, Co and Fe in the CoFe-C / N catalyst are shown in Table 1, and the particle size is shown in Table 2.
[0111] Comparative Example 5
[0112] The procedure was carried out according to the method of Example 1, except that melamine was not added in step (2).
[0113] The contents of nitrogen, Co and Fe in the CoFe-C / N catalyst are shown in Table 1, and the particle size is shown in Table 2.
[0114]
Test Example 1
[0115] (1) Preparation of electrode materials: The samples obtained in the examples and comparative examples were thoroughly ground, and 10 mg of each sample was weighed and added to a mixed solution of 1 mL isopropanol and 1 mL ethanol containing Nafion (the volume ratio of Nafion to ethanol was 1:24, the content of perfluorosulfonic acid polymer in the Nafion solution was 5%, and the solvent of the Nafion solution was water and n-propanol). The mixture was ultrasonically dispersed to ensure uniform dispersion. 20 μL of catalyst slurry was measured and added dropwise to a rotating disk electrode in multiple portions. The electrode was then allowed to dry naturally for testing the hydrogen evolution performance of water electrolysis.
[0116] (2) Hydrogen evolution test conditions: The electrochemical tester used was the Shanghai Chenhua 760E electrochemical workstation. The working electrode was the aforementioned rotating disk electrode loaded with catalyst, the counter electrode was a graphite rod, the reference electrode was a standard hydrogen electrode, and the electrolyte was 1 M KOH solution. After the device was assembled, cyclic voltammetry was first performed, with the voltage range set to 0 to 0.5 V (vs. RHE) and the number of scans set to 200 to ensure sufficient activation of the sample and stability of the working electrode. The hydrogen evolution performance of the working electrode was then measured using linear scanning voltammetry, with the voltage range set to 0 to -0.6 V (vs. RHE), the scan rate set to 0.01 mV / s, and the number of test cycles set to 2. The current density was measured to be 10 mA / cm². 2 At that time, the hydrogen evolution overpotential of each catalytic electrode represents the hydrogen evolution activity of the catalyst; the stability of the catalyst is tested by the it curve and expressed as the decay rate after 12 hours; the electrochemical hydrogen evolution reaction kinetics of the catalyst is represented by the Tafel slope calculation, and the data are shown in Table 3.
[0117] Table 1
[0118] Nitrogen element in catalyst Co element in catalyst Fe element in catalyst Example 1 4.36 40.68 4.05 Example 2 4.05 37.41 6.82 Example 3 4.47 44.08 2.77 Example 4 4.58 40.24 3.86 Example 5 4.19 41.07 4.25 Example 6 4.28 40.93 4.11 Example 7 4.41 40.27 4.16 Example 8 4.22 41.39 3.94 Example 9 4.20 41.54 4.09 Example 10 4.56 39.90 4.33 Example 11 4.05 42.17 4.31 Example 12 4.63 39.52 3.89 Comparative Example 1 4.71 44.37 0 Comparative Example 2 4.41 40.36 4.27 Comparative Example 3 4.75 38.21 3.60 Comparative Example 4 4.22 41.64 4.37 Comparative Example 5 3.82 41.57 4.34
[0119] Table 2
[0120] Catalyst particle size (nm) Example 1 200-250 Example 2 300-350 Example 3 200-250 Example 4 180-220 Example 5 290-350 Example 6 200-300 Example 7 150-200 Example 8 200-300 Example 9 150-250 Example 10 300-350 Example 11 250-300 Example 12 300-350 Comparative Example 1 150-200 Comparative Example 2 250-350 Comparative Example 3 170-220 Comparative Example 4 500-600 Comparative Example 5 250-300
[0121] Table 3
[0122] Hydrogen evolution overpotential (mV) Attenuation rate (%) Tafel(mV / dec) Example 1 177 1.58 98 Example 2 186 1.72 106 Example 3 195 1.66 110 Example 4 227 1.98 143 Example 5 213 3.07 136 Example 6 193 1.86 121 Example 7 187 1.74 109 Example 8 182 1.69 105 Example 9 191 1.96 115 Example 10 189 1.93 116 Example 11 227 2.04 138 Example 12 206 1.92 127 Comparative Example 1 251 1.92 157 Comparative Example 2 435 5.72 348 Comparative Example 3 418 4.37 304 Comparative Example 4 341 5.69 272 Comparative Example 5 264 2.43 173
[0123] The test data from Example 1 and Comparative Example 1 show that, under 1M KOH conditions, when the current density reaches 10 mA / cm², 2 At that time, the hydrogen evolution overpotential, 12-hour decay rate and Tafel slope of the working electrode in Example 1 were significantly lower than those in Comparative Example 1, indicating that the presence of Fe element is beneficial to the improvement of catalyst performance.
[0124] The test data from Example 1 and Comparative Examples 1 and 2 show that when the Fe component aggregates on the Co-ZIF material, changing the structure of the Co-ZIF framework, the catalytic activity of the catalyst is lower than that of the catalyst without the Fe component; while when the Fe element exists in a free state, the catalyst has higher catalytic activity.
[0125] The test data from Examples 1, 4, and 5 and Comparative Examples 3 and 4 show that the catalyst has high activity when the calcination temperature is 700-900℃.
[0126] The test data from Example 1 and Comparative Example 5 show that the introduction of nitrogen-containing compounds is beneficial to improving catalyst performance.
Claims
1. A cobalt-iron bimetallic hydrogen evolution catalyst, characterized in that... The catalyst includes: Co-ZIF material and Fe element freely dispersed in the cavity of the Co-ZIF material; Based on a total catalyst weight of 100%, The catalyst contains 32%-50% Co by weight. The catalyst contains 1%-12% Fe by weight.
2. The catalyst according to claim 1, characterized in that: The catalyst contains 37%-45% Co by weight; and / or, The catalyst contains 3%-7% Fe by weight.
3. The catalyst according to claim 1, characterized in that: The Co-ZIF material is a nitrogen-doped Co-ZIF material; preferably, The nitrogen-doped Co-ZIF material contains 3.8%-4.8% nitrogen by weight, more preferably 4.1%-4.6%.
4. The catalyst according to any one of claims 1-3, characterized in that: The catalyst has a particle size range of 100-500 nm, preferably 180-350 nm.
5. A method for preparing a cobalt-iron bimetallic hydrogen evolution catalyst as described in any one of claims 1-4, characterized in that... The method includes: The catalyst was prepared by mixing a cobalt-containing compound dissolved in solvent A and ferric chloride with 2-methylimidazole dissolved in solvent B, stirring and reacting, and then centrifuging and washing.
6. The method according to claim 5, characterized in that... The method further includes: The catalyst was mixed with a nitrogen-containing compound and then annealed at high temperature under a protective gas atmosphere.
7. The method according to claim 5, characterized in that: The weight ratio of the cobalt-containing compound, ferric chloride, and 2-methylimidazole is 1:(0.01-0.5):(1-10), preferably 1:(0.05-0.3):(2-5); and / or, The concentration of the cobalt-containing compound dissolved in solvent A is 0.01-0.2 mol / L, preferably 0.02-0.06 mol / L; and / or, The concentration of the 2-methylimidazole dissolved in solvent B is 0.1-1.6 mol / L, preferably 0.2-0.8 mol / L.
8. The method according to claim 6, characterized in that: The weight ratio of the catalyst to the nitrogen-containing compound is 1:(0.1-2), preferably 1:(0.3-1).
9. The method according to claim 5, characterized in that: Solvent A is methanol and / or ethanol, preferably methanol; and / or, The cobalt-containing compound is cobalt nitrate hexahydrate and / or cobalt chloride hexahydrate; and / or, The solvent B is methanol and / or ethanol, preferably methanol.
10. The method according to claim 6, characterized in that: The nitrogen-containing compound is melamine and / or urea, preferably melamine; and / or, The protective gas is argon and / or nitrogen, preferably argon.
11. The method according to claim 5, characterized in that: The reaction temperature of the stirring reaction is 10℃-35℃, preferably 20℃-30℃, and / or the reaction time is 8-72 hours, preferably 16-36 hours, and / or the stirring speed is 6000-2000 rpm, preferably 1000-1600 rpm.
12. The method according to claim 6, characterized in that: The high-temperature annealing is performed at a temperature of 700℃-900℃, preferably 760℃-840℃, and / or at a heating rate of 1-10℃ / min, preferably 3-5℃ / min, and / or at a annealing time of 1-8h, preferably 3-5h.
13. The application of a cobalt-iron bimetallic hydrogen evolution catalyst as described in any one of claims 1-4 or a cobalt-iron bimetallic hydrogen evolution catalyst prepared by the method as described in any one of claims 5-12 in the field of hydrogen production by water electrolysis.