Preparation method of high-entropy composite oxygen carriers for hydrogen production by chemical looping gasification

Abstract

The application provides a preparation method of a high-entropy composite oxygen carrier for hydrogen production by chemical looping gasification. The method combines low-temperature ultrasonic mixing, electrochemical activation, and low-temperature calcination processes to prepare a high-entropy composite oxygen carrier with excellent oxygen release performance and high stability. The specific steps include: dissolving nitrate salts of Fe, Co, Ni, Cu, and Mn in deionized water at a molar ratio of 1:1:1:1:1, adding sodium chloride (NaCl) and polyvinylpyrrolidone (PVP) to adjust the solution properties, and forming a uniform sol; obtaining anhydrous gel powder by low-temperature freeze drying; then performing electrochemical activation and graphene compounding; finally, low-temperature calcination at 300-500 DEG C, washing and drying to obtain a high-entropy composite oxygen carrier. The oxygen carrier has a high specific surface area (> 50 m 2 / g), excellent pore size distribution (2-50 nm), good crystal structure (cubic system), and more than 100 redox cycle stabilities, with an oxygen transmission rate increase of 50%, an anti-sintering ability enhancement of more than 40%, significantly improved oxygen release performance and catalytic activity, while avoiding the sintering problem caused by traditional high-temperature calcination, reducing energy consumption, and being suitable for efficient and stable hydrogen production by chemical looping gasification.

Description

Technical Field

[0001] This invention relates to a method for preparing a high-entropy composite oxygen carrier, particularly for the preparation of a high-entropy oxygen carrier in chemical looping gasification hydrogen production. This invention is widely applicable to chemical looping gasification hydrogen production, chemical looping reforming, and other clean energy technology fields, and has significant industrial application value. Background Technology

[0002] With increasing global energy demand and a growing focus on sustainable energy solutions, the potential of hydrogen as a clean energy source is gaining increasing attention. In the field of hydrogen production, chemical looping gasification technology has become a research hotspot due to its high efficiency and low energy consumption. In this technology, the oxygen carrier is a key material responsible for providing oxygen to promote the gasification reaction. While traditional high-entropy oxygen carriers exhibit good performance in catalysis and oxygen release, existing preparation methods often rely on high-temperature calcination, which easily leads to sintering of the oxygen carrier and loss of catalytic activity under high-temperature conditions, and also results in high energy consumption.

[0003] Several studies have proposed different methods for preparing high-entropy oxygen supports. For example, patent CN 118988338A (A high-entropy oxide and its preparation method and application) uses a combination of PVP template method and freeze-drying technology to prepare a high-entropy oxide with good catalytic activity. Another patent CN 116654993 A (A high-entropy oxide oxygen support and its preparation method and application) uses the citric acid sol-gel method combined with a mixed solution of polyethylene glycol and water to prepare a high-entropy oxide with good oxygen release performance. In addition, patent CN 117019168A (A highly stable transition metal high-entropy oxygen carrier and its preparation method and application) proposes a highly stable high-entropy oxygen carrier by combining different transition metals with non-transition metals, and has applied it in chemical looping gasification.

[0004] Although the above technologies have made some progress in improving the catalytic performance and stability of high-entropy oxygen supports, they still face the following challenges:

[0005] (1) Existing methods for preparing high-entropy oxygen carriers often rely on high-temperature calcination, which can lead to sintering and loss of activity of the oxygen carrier;

[0006] (2) Existing preparation methods are generally inefficient and have high energy consumption;

[0007] (3) Most methods cannot maintain the stability and catalytic activity of the oxygen carrier in complex atmospheres for a long time.

[0008] Therefore, this invention proposes an innovative method for preparing high-entropy composite oxygen carriers. By combining low-temperature ultrasonic-assisted mixing, electrochemical activation, and low-temperature calcination, the oxygen release capacity and stability can be significantly improved.

[0009] It combines high efficiency and catalytic activity, while avoiding the sintering problems of traditional methods, reducing energy consumption, and meeting the demand for efficient and stable oxygen carriers in chemical looping gasification hydrogen production. Summary of the Invention

[0010] To achieve the above objectives, this invention provides a method for preparing a high-entropy composite oxygen carrier (FeCoNiCuMnOx high-entropy oxygen carrier), comprising the following steps:

[0011] S1: Preparation and mixing of metal salt solutions;

[0012] S2: Add electrolytes and gelling agents to a metal salt solution to form a stable metal complex sol;

[0013] S3: Freeze-dry the sol at low temperature to obtain anhydrous gel powder;

[0014] S4: Electrochemical activation and compounding of freeze-dried powder;

[0015] S5: After the composite material is calcined at low temperature, it undergoes post-processing steps such as sieving and washing to obtain a high-entropy composite oxygen carrier.

[0016] The metal salt dissolving elements mentioned in step S1 are selected as iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), and manganese (Mn) as the main metal elements, and the preferred molar ratio is Fe:Co:Ni:Cu:Mn = 1:1:1:1:1.

[0017] Further, at room temperature (approximately 25°C), the nitrates of the above metals (Fe(NO3)3·9H2O, Co(NO3)2·6H2O, Ni(NO3)2·6H2O, Cu(NO3)2·5H2O, Mn(NO3)2·4H2O) were weighed out according to the above proportions and added one by one to deionized water. The mixture was stirred at 300 rpm using a magnetic stirrer until all the metal salts were completely dissolved to form a homogeneous solution, thus preparing a mixed metal salt solution with a concentration of 0.1 mol / L.

[0018] The ultrasonic wave mentioned in step S1 is an ultrasonic cleaner with a power of 500W and a frequency of 20kHz.

[0019] Furthermore, the above-mentioned metal salt solution is placed in an ultrasonic cleaner and subjected to ultrasonic treatment for 30 minutes, with intermittent operation (5 minutes of ultrasonic treatment followed by 2 minutes of rest) to prevent overheating.

[0020] The electrolyte mentioned in step S2 is a sodium chloride (NaCl) solution.

[0021] Further, sodium chloride (NaCl) is added to the metal salt solution prepared in step S1, and the mixture is stirred continuously at room temperature until the sodium chloride is completely dissolved, so that its concentration reaches 0.05 mol / L.

[0022] The gelling agent mentioned in step S2 is polyvinylpyrrolidone (PVP).

[0023] Further, PVP is dissolved in a small amount of deionized water to prepare a PVP solution with a concentration of 0.5%-2%, which is then slowly added to the metal salt solution prepared in step S1 and stirred continuously for 30 minutes until a uniform sol is formed.

[0024] The freeze-drying described in step S3 is performed using a freeze dryer.

[0025] Further, the sol prepared in step S2 is placed in a refrigerator at -10 to -30°C for 2 hours to pre-cool until the surface begins to freeze.

[0026] Further, the pre-cooled sol was transferred to a freeze dryer, with the temperature set at -40 to -60°C, the pressure at 0.05 mbar to 0.1 mbar, and the drying time at 24 hours, until an anhydrous gel was obtained.

[0027] The electrochemical electrolyte solution mentioned in step S4 is a 0.1 mol / L sodium sulfate (Na2SO4) solution.

[0028] Furthermore, the lyophilized powder material was placed together with a platinum electrode in an electrochemical cell, using an Ag / AgCl electrode as a reference electrode.

[0029] Step S4 electrochemical activation parameters are: at room temperature, apply a voltage of 1-3V, and set the activation time to 1-3h, and perform cyclic voltammetry scans at a scan rate of 5mV / s.

[0030] The composite material described in step S4 uses an oxygen carrier:graphene ratio of 1:0.05-0.1 by mass.

[0031] Furthermore, under the aforementioned electrochemical activation conditions, electrochemical deposition was performed for 1 hour to ensure good composite formation of graphene and oxygen carrier.

[0032] The low-temperature calcination described in step S5 is carried out in a Marfé furnace.

[0033] The calcination atmosphere described in step S5 can be air, nitrogen, or hydrogen.

[0034] Furthermore, the calcination temperature in step S5 is 300-450℃, the calcination time is 3-6h, and the heating rate is 1-4℃ / min.

[0035] Furthermore, the calcined material is washed with deionized water until the pH of the washing solution is close to neutral.

[0036] Furthermore, the washed material is dried at 60°C for 12 hours until constant weight is achieved, thus obtaining the final high-entropy composite oxygen carrier.

[0037] The high-entropy composite oxygen carrier prepared by the above steps in this invention has the following significant advantages:

[0038] (1) High oxygen release capacity: The combination of low-temperature ultrasonic-assisted mixing and electrochemical activation technology can significantly improve the oxygen release rate and efficiency of the oxygen carrier under high temperature environment.

[0039] (2) Excellent catalytic performance: The introduction of composite materials improves the catalytic activity and selectivity of the oxygen carrier, making it suitable for chemical looping gasification to produce hydrogen and other catalytic reactions.

[0040] (3) High stability and cycle performance: The low-temperature calcination process avoids the sintering problem in the traditional high-temperature calcination process, and the oxygen carrier maintains high stability and cycle performance during long-term reaction.

[0041] (4) Energy saving and environmental protection: This method reduces energy consumption through low-temperature synthesis and electrochemical activation processes, and avoids pollution generated during traditional high-temperature calcination. Attached Figure Description

[0042] Figure 1 Flowchart of a preparation process for a high-entropy composite oxygen carrier for chemical looping gasification hydrogen production Detailed Implementation

[0043] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in this technical field.

[0044] Example 1: Preparation of high-entropy composite oxygen carrier FeCoNiCuMn at 500℃

[0045] (1) Preparation and mixing of metal salt solution: Weigh metal nitrates in a molar ratio of Fe:Co:Ni:Cu:Mn = 1:1:1:1:1 and dissolve them in deionized water to prepare a mixed solution with a concentration of 0.1 mol / L.

[0046] (2) Add electrolytes and gelling agents: Add 0.05 mol / L NaCl solution and 1% PVP solution to the above solution, stir for 30 minutes to form a uniform sol.

[0047] (3) Low-temperature freeze drying: The sol was pre-cooled to -20℃ and then freeze-dried at -50℃ and 0.1mbar for 24 hours to obtain anhydrous gel powder.

[0048] (4) Electrochemical activation and recombination: The lyophilized powder and platinum electrode were placed in a 0.1 mol / L Na2SO4 solution, and a voltage of 1.5 V was applied for activation for 2 hours. Then, graphene with a mass ratio of 1:0.05 was added, and electrochemical deposition was continued for 1 hour to complete the recombination process.

[0049] (5) Low-temperature calcination and post-treatment: The composite material was placed in a muffle furnace and heated to 500℃ at a heating rate of 2℃ / min, held for 4 hours, and then naturally cooled to room temperature. After removal, it was washed with deionized water until the pH of the washing solution was close to neutral, and dried at 60℃ for 12 hours to obtain FeCoNiCuMnOx high-entropy composite oxygen carrier, denoted as FeCoNiCuMn-500℃.

[0050] The high-entropy composite oxygen carrier prepared by the above steps has a specific surface area of ​​60 m². 2 / g, with a pore size distribution between 2-50nm, a cubic crystal structure, an oxygen transport rate increased by 50%, an anti-sintering ability increased by more than 40%, and a redox cycle stability of more than 100 cycles, significantly improving oxygen release performance and catalytic activity.

[0051] Using pine wood powder as raw material, chemical looping gasification hydrogen production was tested at 800℃. The reduction time was 35 min, the syngas yield was 0.98 Nm3 / h, the syngas selectivity was 75%, and the hydrogen purity was 99.1%. After 100 cycles, the performance decreased by 3.1%, showing good reaction characteristics.

[0052] Example 2: Preparation of high-entropy composite oxygen carrier FeCoNiCuMn - 450℃

[0053] (1) Preparation and mixing of metal salt solution: Weigh metal nitrates in a molar ratio of Fe:Co:Ni:Cu:Mn = 1:1:1:1:1 and dissolve them in deionized water to prepare a mixed solution with a concentration of 0.1 mol / L.

[0054] (2) Adding electrolytes and gelling agents: Add 0.05 mol / L NaCl solution and a gelling agent to the above solution.

[0055] A 1.5% PVP solution was stirred for 30 minutes to form a homogeneous sol.

[0056] (3) Low-temperature freeze drying: The sol was pre-cooled to -15℃ and then freeze-dried at -45℃ and 0.08mbar for 24 hours to obtain anhydrous gel powder.

[0057] (4) Electrochemical activation and recombination: The lyophilized powder and platinum electrode were placed in a 0.1 mol / L Na2SO4 solution, and a voltage of 1.2 V was applied for activation for 2 hours. Then, graphene with a mass ratio of 1:0.07 was added, and electrochemical deposition was continued for 1 hour to complete the recombination process.

[0058] (5) Low-temperature calcination and post-treatment: The composite material was placed in a muffle furnace and heated to 450℃ at a heating rate of 2℃ / min, held for 3 hours, and then naturally cooled to room temperature. After removal, it was washed with deionized water until the pH of the washing solution was close to neutral, and dried at 60℃ for 12 hours to obtain the high-entropy composite oxygen carrier, denoted as FeCoNiCuMn-450℃.

[0059] The high-entropy composite oxygen carrier prepared by the above steps has a specific surface area of ​​58 m². 2 / g, with a pore size distribution between 3-45nm, a cubic crystal structure, an oxygen transport rate increased by 48%, an anti-sintering ability increased by more than 38%, and a redox cycle stability of more than 100 cycles.

[0060] Using pine wood powder as raw material, chemical looping gasification hydrogen production was tested at 800℃. The reduction time was 35 min, the syngas yield was 0.97 Nm3 / h, the syngas selectivity was 77%, and the hydrogen purity was 99.2%. After 100 cycles, the performance decreased by 3.3%, showing good reaction characteristics.

[0061] Example 3: Preparation of high-entropy composite oxygen carrier FeCoNiCuMn - 400℃

[0062] (1) Preparation and mixing of metal salt solution: Weigh metal nitrates in a molar ratio of Fe:Co:Ni:Cu:Mn = 1:1:1:1:1 and dissolve them in deionized water to prepare a mixed solution with a concentration of 0.1 mol / L.

[0063] (2) Add electrolytes and gelling agents: Add 0.05 mol / L NaCl solution and 2% PVP solution to the above solution, stir for 30 minutes to form a uniform sol.

[0064] (3) Low-temperature freeze drying: The sol was pre-cooled to -25℃ and then freeze-dried at -55℃ and 0.1mbar for 24 hours to obtain anhydrous gel powder.

[0065] (4) Electrochemical activation and recombination: The lyophilized powder and platinum electrode were placed in a 0.1 mol / L Na2SO4 solution, and a voltage of 1.8 V was applied for activation for 1.5 hours. Then, graphene with a mass ratio of 1:0.08 was added, and electrochemical deposition was continued for 1 hour to complete the recombination process.

[0066] (5) Low-temperature calcination and post-treatment: The composite material was placed in a muffle furnace and heated to 400℃ at a heating rate of 2℃ / min, held for 5 hours, and then naturally cooled to room temperature. After removal, it was washed with deionized water until the pH of the washing solution was close to neutral, and dried at 60℃ for 12 hours to obtain the high-entropy composite oxygen carrier, denoted as FeCoNiCuMn-400℃.

[0067] The high-entropy composite oxygen carrier prepared by the above steps has a specific surface area of ​​55 m². 2 / g, with pore size distribution between 2-50nm, cubic crystal structure, oxygen transport rate increased by 45%, anti-sintering ability increased by more than 35%, and redox cycle stability exceeding 100 cycles.

[0068] Using pine wood powder as raw material, chemical looping gasification hydrogen production was tested at 800℃. The reduction time was 35 min, the syngas yield was 0.96 Nm3 / h, the syngas selectivity was 78%, and the hydrogen purity was 99.4%. After 100 cycles, the performance decreased by 3.5%, showing good reaction characteristics.

[0069] Example 4: Preparation of high-entropy composite oxygen carrier FeCoNiCuMn - 350℃

[0070] (1) Preparation and mixing of metal salt solution: Weigh metal nitrates in a molar ratio of Fe:Co:Ni:Cu:Mn = 1:1:1:1:1 and dissolve them in deionized water to prepare a mixed solution with a concentration of 0.1 mol / L.

[0071] (2) Add electrolyte and gelling agent: Add 0.05 mol / L NaCl solution and 0.5% PVP solution to the above solution, stir for 30 minutes to form a uniform sol.

[0072] (3) Low-temperature freeze drying: The sol was pre-cooled to -10℃ and then freeze-dried at -40℃ and 0.05mbar for 24 hours to obtain anhydrous gel powder.

[0073] (4) Electrochemical activation and recombination: The lyophilized powder and platinum electrode were placed in a 0.1 mol / L Na2SO4 solution, and a voltage of 1.5 V was applied for activation for 2 hours. Then, graphene with a mass ratio of 1:0.06 was added, and electrochemical deposition was continued for 1 hour to complete the recombination process.

[0074] (5) Low-temperature calcination and post-treatment: The composite material was placed in a muffle furnace and heated to 350℃ at a heating rate of 2℃ / min, held for 6 hours, and then naturally cooled to room temperature. After removal, it was washed with deionized water until the pH of the washing solution was close to neutral, and dried at 60℃ for 12 hours to obtain the high-entropy composite oxygen carrier, denoted as FeCoNiCuMn-350℃.

[0075] The high-entropy composite oxygen carrier prepared by the above steps has a specific surface area of ​​52 m². 2 / g, with a pore size distribution between 2-40nm, a cubic crystal structure, an oxygen transport rate increased by 42%, an anti-sintering ability increased by more than 32%, and a redox cycle stability of more than 100 cycles.

[0076] Using pine wood powder as raw material, chemical looping gasification hydrogen production was tested at 800℃. The reduction time was 35 min, the syngas yield was 0.95 Nm3 / h, the syngas selectivity was 74%, and the hydrogen purity was 99.5%. After 100 cycles, the performance decreased by 3.6%, showing good reaction characteristics.

[0077] Example 5: Preparation of high-entropy composite oxygen carrier FeCoNiCuMn - 500℃ - high graphene content

[0078] (1) Preparation and mixing of metal salt solution: Weigh metal nitrates in a molar ratio of Fe:Co:Ni:Cu:Mn = 1:1:1:1:1 and dissolve them in deionized water to prepare a mixed solution with a concentration of 0.1 mol / L.

[0079] (2) Add electrolyte and gelling agent: Add 0.05 mol / L NaCl solution and 1.2% PVP solution to the above solution, stir for 30 minutes to form a uniform sol.

[0080] (3) Low-temperature freeze drying: The sol was pre-cooled to -20℃ and then freeze-dried at -50℃ and 0.1mbar for 24 hours to obtain anhydrous gel powder.

[0081] (4) Electrochemical activation and recombination: The lyophilized powder and platinum electrode were placed in a 0.1 mol / L Na2SO4 solution, and a voltage of 1.0 V was applied for activation for 3 hours. Then, graphene with a mass ratio of 1:0.09 was added, and electrochemical deposition was continued for 1 hour to complete the recombination process.

[0082] (5) Low-temperature calcination and post-treatment: The composite material was placed in a muffle furnace and heated to 500℃ at a heating rate of 2℃ / min, held for 4 hours, and then naturally cooled to room temperature. After removal, it was washed with deionized water until the pH of the washing solution was close to neutral, and dried at 60℃ for 12 hours to obtain a high-entropy composite oxygen carrier, denoted as FeCoNiCuMn-500℃-high graphene content.

[0083] The high-entropy composite oxygen carrier prepared by the above steps has a specific surface area of ​​62 m². 2 / g, with a pore size distribution between 2-50nm, a cubic crystal structure, an oxygen transport rate increased by 52%, an anti-sintering ability increased by more than 42%, and a redox cycle stability of more than 100 cycles.

[0084] Using pine wood powder as raw material, chemical looping gasification hydrogen production was tested at 800℃. The reduction time was 35 min, the syngas yield was 0.98 Nm3 / h, the syngas selectivity was 80%, and the hydrogen purity was 99.6%. After 100 cycles, the performance decreased by 3.2%, showing good reaction characteristics.

[0085] Example 6: Preparation of high-entropy composite oxygen carrier FeCoNiCuMn - 400℃ - high graphene content

[0086] (1) Preparation and mixing of metal salt solution: Weigh metal nitrates in a molar ratio of Fe:Co:Ni:Cu:Mn = 1:1:1:1:1 and dissolve them in deionized water to prepare a mixed solution with a concentration of 0.1 mol / L.

[0087] (2) Add electrolyte and gelling agent: Add 0.05 mol / L NaCl solution and 1.8% PVP solution to the above solution, stir for 30 minutes to form a uniform sol.

[0088] (3) Low-temperature freeze drying: The sol was pre-cooled to -20℃ and then freeze-dried at -50℃ and 0.1mbar for 24 hours to obtain anhydrous gel powder.

[0089] (4) Electrochemical activation and recombination: The lyophilized powder and platinum electrode were placed in a 0.1 mol / L Na2SO4 solution, and a voltage of 2.0 V was applied for activation for 1 hour. Then, graphene with a mass ratio of 1:0.1 was added, and electrochemical deposition was continued for 1 hour to complete the recombination process.

[0090] (5) Low-temperature calcination and post-treatment: The composite material was placed in a muffle furnace and heated to 400℃ at a heating rate of 2℃ / min, held for 4 hours, and then naturally cooled to room temperature. After removal, it was washed with deionized water until the pH of the washing solution was close to neutral, and dried at 60℃ for 12 hours to obtain a high-entropy composite oxygen carrier, denoted as FeCoNiCuMn-400℃-high graphene content.

[0091] The high-entropy composite oxygen carrier prepared by the above steps has a specific surface area of ​​56 m². 2 / g, with pore size distribution between 2-50nm, cubic crystal structure, oxygen transport rate increased by 46%, anti-sintering ability increased by more than 36%, and redox cycle stability exceeding 100 cycles.

[0092] Using pine wood powder as raw material, chemical looping gasification for hydrogen production was tested at 800℃. The reduction time was 35 min, the syngas yield was 0.97 Nm3 / h, the syngas selectivity was 81%, and the hydrogen purity was 99.3%. After 100 cycles, the performance decreased by 3.5%, showing good reaction characteristics.

[0093] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0094] The oxygen carrier preparation parameters for the above embodiments are shown in Table 1:

[0095] Table 1

[0096]

[0097] The test results of the high-entropy composite oxygen carrier prepared in the examples during chemical looping gasification are shown in Table 2.

[0098] Table 2

[0099]

Claims

1. A method for preparing a high-entropy composite oxygen carrier, characterized in that, Includes the following steps: S1. Preparation and mixing of metal salt solutions: Weigh out the nitrates of iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), and manganese (Mn) in a molar ratio of Fe:Co:Ni:Cu:Mn = 1:1:1:1:1, dissolve them in deionized water, and prepare a mixed metal salt solution with a concentration of 0.1 mol / L. S2. Add electrolytes and gelling agents: Add a 0.05 mol / L sodium chloride (NaCl) solution and a 0.5%-2% polyvinylpyrrolidone (PVP) solution to the above solution to adjust the ionic strength and viscosity of the solution and form a uniform sol. S3. Low-temperature freeze drying: Pre-cool the sol to -20℃, then freeze-dry at -50℃. Freeze-dry at 0.1 mbar for 24 hours to obtain anhydrous gel powder; S4. Electrochemical activation and recombination: The lyophilized powder and platinum electrode were placed in a 0.1 mol / L sodium sulfate solution, and a voltage of 1.5 V was applied for 2 hours for electrochemical activation. Then, graphene was added, and the mass ratio of graphene to oxygen carrier was 1:0.

05. Electrochemical deposition was continued for 1 hour to complete the recombination process. S5. Low-temperature calcination and post-treatment: The composite material was placed in a muffle furnace and heated to 500°C at a heating rate of 2°C / min, held for 4 hours, and then naturally cooled to room temperature; after removal, it was washed with deionized water and dried for 12 hours to obtain a high-entropy composite oxygen carrier.

2. The method according to claim 1, wherein, The low-temperature calcination process is carried out in an atmosphere of air, nitrogen, or hydrogen.

3. According to the method of claim 1, after the low-temperature calcination, the composite material is washed in deionized water until the pH of the washing solution is close to neutral; then, it is dried at 60°C for 12 hours until constant weight is obtained to obtain a high-entropy composite oxygen carrier.

4. The method according to claim 1, wherein, The high-entropy composite oxygen carrier has a specific surface area greater than 50 m². 2 / g, with pore size distribution between 2nm and 50nm, cubic crystal structure, and redox cycle stability exceeding 100 cycles.

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