Preparation and application of mesoporous carbon / Prussian blue phosphide composite electrode

Abstract

The invention relates to preparation and application of a mesoporous carbon / Prussian blue phosphide composite electrode, and belongs to the technical field of preparation of functional materials. A nickel-cobalt Prussian blue analogue electrode material is synthesized by adopting a coprecipitation method, and then an oxide (PBA-O), a sulfide (PBA-S) and a phosphide (PBA-P) derived from a Prussian blue cube are obtained through vulcanization and phosphorization modification. A micro-physical structure of PBA is designed, and the influence of vulcanization and phosphorization on PBA is deeply discussed. In addition, the SAC is doped into the previously prepared PBA, so that the SAC-coated PBA-P composite electrode material with excellent charge storage capacity is successfully prepared. In addition, 0.01 M potassium ferricyanide is added into a 3M KOH electrolyte, so that the coulombic efficiency of the material under the conditions of high current density and long cycle time is remarkably improved. Finally, by using the synthesized SAC coated PBA-P electrode material as a positive electrode material and selecting activated carbon as a negative electrode material, an asymmetric capacitor is successfully constructed. In addition, the potential and possible development prospect of the novel electrode material in future practical application are also discussed, and an innovative solution is expected to be provided for the field of energy storage.

Description

Technical Field

[0001] The invention belongs to the technical field of functional material preparation, and specifically relates to the preparation and application of a mesoporous carbon / Prussian blue phosphide composite electrode. Background Art

[0002] It is particularly important to accelerate the development of clean energy technology, which not only involves the innovation of power generation methods, but also includes the research and development of new energy materials and the improvement of emission reduction technologies. Therefore, the development of efficient and stable energy storage and conversion technologies, as well as equipment that combines these new technologies with clean energy, is of great significance for solving energy transmission problems, improving global energy efficiency, and reducing environmental pollution.

[0003] In the context of capacitive energy storage, it is crucial to maintain high cycling stability while improving energy density and Coulombic efficiency. Among the most widely used metal-organic frameworks, especially in the field of energy storage devices, Prussian blue analogs (PBAs) have attracted considerable attention due to their easy modification of three-dimensional frameworks, high specific surface area, abundant potential active sites and low cost. However, the low conductivity of PBAs limits their further application as capacitive electrodes. How to partially or completely overcome the intrinsic limitations of polycyclic aromatic hydrocarbons by controlling the preparation method has always been a problem that researchers have been working hard to solve. Despite these challenges, PBAs can be modified in various ways due to their excellent cubic structure. For example, the cubic structure of PBA is modified and converted into interesting structures such as hollow cubes and regular polygons.

[0004] In addition, growing PBA on highly conductive materials is also an excellent way to improve performance. For example, materials such as polypyrrole nanotubes (PNTs), carbon nanotubes (CNTs), and carbon cloth (CC) can serve as excellent symbiotic materials. The porous structure of mesoporous carbon (SAC) prepared in some reports is conducive to improving the conduction of electrons and ions on the surface of the material and in the electrolyte during charging and discharging, which can significantly improve the conductivity of the material. However, improving the conductivity of PBA electrode materials by the above methods may not completely solve their inherent defects. With the increase of current density, some PBA-based electrode materials present a higher charging platform and a lower discharge platform, resulting in a significant decrease in their Coulombic efficiency. Summary of the invention

[0005] In view of this, one of the objects of the present invention is to provide a method for preparing and applying a mesoporous carbon / Prussian blue phosphide composite electrode; a second object of the present invention is to provide a method for preparing and applying a mesoporous carbon / Prussian blue phosphide composite electrode; a third object of the present invention is to provide a method for preparing and applying a mesoporous carbon / Prussian blue phosphide composite electrode in electrochemistry.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] 1. A method for preparing and applying a mesoporous carbon / Prussian blue phosphide composite electrode, the preparation method comprising the following steps:

[0008] (1) First, dissolve sodium citrate and nickel nitrate and stir to obtain a uniform solution A. At the same time, dissolve potassium hexacyanocobaltate in deionized water to form a uniform solution B. Mix solution A and solution B, stir continuously for 10 minutes, seal and age at room temperature for 12 hours. Wash with water several times until the upper solution becomes clear and a light blue precipitate is obtained. Finally, dry the precipitate in an oven at 60°C for 12 hours to obtain PBA.

[0009] (2) Synthesis steps of PBA oxide, PBA sulfide and PBA phosphide

[0010] PBA-O powder was prepared by calcination. PBA was heated to 400°C in air and heated at 400°C for 2 hours. PBA-S powder was prepared by hydrothermal method. PBA and sodium sulfate were added to deionized water and stirred magnetically to form a uniform solution. Then, the solution was transferred to a stainless steel autoclave lined with polytetrafluoroethylene and transferred to an oven for heating. After the reaction was completed, it was washed with deionized water and ethanol and dried to obtain PBA-S. PBA-P powder was prepared by calcination. Monohydrate sodium hypophosphite powder and PBA powder were evenly dispersed on a quartz boat and transported to the upstream and downstream sides of the tube furnace respectively. The sample was placed in a nitrogen environment and then calcined at 400°C for 2 hours.

[0011] (3) Synthesis steps of mesoporous carbon-supported NiCo PBA phosphide

[0012] In the process of preparing NiCo PBA, SAC was added when solution A was mixed with solution B, and the other steps remained unchanged, and SAC@PBA was obtained after drying. Similarly, when SAC@PBA-P was prepared by calcination, PBA was replaced by SAC@PBA, and the other preparation conditions were the same as PBA-P.

[0013] Preferably, in step (1), the molar ratio of the raw materials is sodium citrate: nickel nitrate: potassium hexacyanocobaltate = 12-24 mmol: 8-16 mmol: 2-5 mmol.

[0014] Preferably, the solution is sealed and aged at room temperature for 8-16 hours, the obtained solution is washed 2-6 times by centrifugation with water, and finally the precipitate is dried in an oven at 60-80° C. for 12-16 hours to obtain PBA.

[0015] Preferably, the PBA-O powder is prepared by calcination. PBA (100-200 mg) is heated in air at 2-5 °C min-1 Heating to 400-600℃

[0016] Preferably, heating is performed at 400-600° C. for 2-8 hours.

[0017] Preferably, PBA-S powder is prepared by hydrothermal method. PBA (100-200 mg) and 8-12 mmol sodium sulfate (Na 2 S·9H 2 O, ≥99.0%) was added into 100-150 ml of deionized water and stirred magnetically for 5-20 minutes to form a uniform solution.

[0018] Preferably, the solution is transferred to a stainless steel autoclave lined with polytetrafluoroethylene, and then transferred to an oven and heated to 70-90° C. for 1-3 hours.

[0019] Preferably, drying is performed at 60-80° C. for 12-16 hours to obtain PBA-S.

[0020] Preferably, the PBA-P powder is prepared by calcination. 2 H 2 6H 2 O, ≥99.0%) powder (500-800 mg) and PBA powder (100-200 mg) were uniformly dispersed.

[0021] Preferably, the sample is placed in a nitrogen environment and the temperature rise rate is set at 2-5 °C min -1 , and then continue calcining at 400-500°C for 2-5 hours.

[0022] Preferably, in the process of preparing NiCo PBA, 50-100 mg of SAC is added when solution A is mixed with solution B, and the other steps remain unchanged, and SAC@PBA is obtained after drying. Similarly, when preparing SAC@PBA-P by calcination, PBA is replaced with SAC@PBA, and the other preparation conditions are the same as PBA-P.

[0023] The beneficial effects of the present invention are:

[0024] 1. The present invention discloses a method for preparing a nickel mesoporous carbon-loaded NiCo-type Prussian blue phosphide composite electrode material. The preparation method first adjusts the material ratio, temperature, time, etc. to prepare nanoparticles with good dispersibility and uniform particle size, nanosheets and other microscopic electrode materials. Electrode materials with different nano sizes and morphologies are synthesized by introducing Mn, secondary modification and other methods.

[0025] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the following examination and study, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below in conjunction with the accompanying drawings, wherein:

[0027] Figure 1 This is a flow chart for preparing the mesoporous carbon / Prussian blue phosphide composite electrode material of the present invention;

[0028] Figure 2 The SEM images of the mesoporous carbon-modified Prussian blue phosphide composite electrode material prepared in Example 1, where (a) PBA, (b) SAC@PBA-P

[0029] Figure 3 TEM images of the preparation and application of a mesoporous carbon / Prussian blue phosphide composite electrode prepared in Example 1, where (a) PBA, (b) SAC@PBA-P

[0030] Figure 4 (a) Pore distribution diagram and (b) N2 adsorption / desorption isotherms of the mesoporous carbon-modified Prussian blue phosphide composite electrode materials PBA and SAC@PBA-P prepared in Example 1

[0031] Figure 5 The test performance of the mesoporous carbon modified Prussian blue phosphide composite electrode material prepared in Example 1, (a) CC curve (current density is 1A g-1), (b) CV curve (scan rate is 50mV s-1), (c) specific capacitance, (d) impedance diagram. Electrochemical performance of SAC@PBA-P, (e) CV curve, (f) CC curve, (g) cyclic test capacitance retention and CC curve at a current density of 12A g-1, (h) impedance diagram before and after the cyclic test, (i) equivalent circuit diagram DETAILED DESCRIPTION

[0032] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0033] Example 1

[0034] Preparation and application of a mesoporous carbon / Prussian blue phosphide composite electrode, the specific preparation method is as follows:

[0035] (1) First, 12 mmol of sodium citrate (C 6 H 5 O 7 Na 3 ,≥98.0%) and 8mmol nickel nitrate (Ni(NO 3 ) 2 6H 2 O, ≥99.0%) was dissolved in 300 ml of deionized water and stirred magnetically for 5 minutes to obtain a uniform solution A. At the same time, 5 mmol potassium hexacyanocobaltate (C 6 CoK 3 N 6 , ≥99.9%) was dissolved in 200 ml of deionized water to form a uniform solution B, and solution B was slowly poured into solution A while stirring evenly. The mixture of solution A and solution B was continuously stirred at an appropriate rate for 10 minutes, and the obtained solution was sealed and aged at room temperature for 12 hours. The obtained solution was centrifuged with water several times until the upper solution became clear to obtain a light blue precipitate. Finally, the precipitate was dried in an oven at 60°C for 12 hours to obtain PBA.

[0036] (2) Synthesis steps of PBA oxide

[0037] PBA-O powder was prepared by calcination. PBA (100 mg) was heated in air at 2 °C min -1 Heat to 400℃ and heat at 400℃ for 2 hours. After the reaction is completed, wash with deionized water and ethanol and centrifuge several times until the solution in the test tube is clear and precipitated. Finally, dry at 60℃ for 12 hours to obtain PBA-O.

[0038] (3) Synthesis steps of mesoporous / NiCo PBA phosphide

[0039] In the process of preparing NiCo PBA, 50 mg of SAC was added when solution A was mixed with solution B, and the other steps remained unchanged, and SAC@PBA was obtained after drying. Similarly, when SAC@PBA-P was prepared by calcination, PBA was replaced by SAC@PBA, and the other preparation conditions were the same as PBA-P.

[0040] Example 2

[0041] Preparation and application of a mesoporous carbon / Prussian blue phosphide composite electrode, the specific preparation method is as follows:

[0042] (1) First, 12 mmol of sodium citrate (C 6 H 5 O 7 Na 3 ,≥98.0%) and 8mmol nickel nitrate (Ni(NO 3 ) 2 6H 2 O, ≥99.0%) was dissolved in 300 ml of deionized water and stirred magnetically for 5 minutes to obtain a uniform solution A. At the same time, 5 mmol potassium hexacyanocobaltate (C 6 CoK 3 N 6 , ≥99.9%) was dissolved in 200 ml of deionized water to form a uniform solution B, and solution B was slowly poured into solution A while stirring evenly. The mixture of solution A and solution B was continuously stirred at an appropriate rate for 10 minutes, and the obtained solution was sealed and aged at room temperature for 12 hours. The obtained solution was centrifuged with water several times until the upper solution became clear to obtain a light blue precipitate. Finally, the precipitate was dried in an oven at 60°C for 12 hours to obtain PBA.

[0043] (2) Synthesis steps of PBA sulfide

[0044] PBA-S powder was prepared by hydrothermal method. PBA (100 mg) and 8 mmol sodium sulfate (Na 2 S·9H 2 O, ≥99.0%) was added to 100 ml of deionized water and magnetically stirred for 5 minutes to form a uniform solution. Then, the solution was transferred to a stainless steel autoclave lined with polytetrafluoroethylene, transferred to an oven and heated to 90°C for 1 hour. After the reaction was completed, it was washed with deionized water and ethanol and centrifuged several times until the solution in the test tube was clear and precipitated. Finally, it was dried at 60°C for 12 hours to obtain PBA-S.

[0045] (3) Synthesis steps of mesoporous carbon-supported NiCo PBA phosphide

[0046] In the process of preparing NiCo PBA, 50 mg of SAC was added when solution A was mixed with solution B, and the other steps remained unchanged, and SAC@PBA was obtained after drying. Similarly, when SAC@PBA-P was prepared by calcination, PBA was replaced by SAC@PBA, and the other preparation conditions were the same as PBA-P.

[0047] Example 3

[0048] Preparation and application of a mesoporous carbon / Prussian blue phosphide composite electrode, the specific preparation method is as follows:

[0049] (1) First, 12 mmol of sodium citrate (C 6 H5 O 7 Na 3 ,≥98.0%) and 8mmol nickel nitrate (Ni(NO 3 ) 2 6H 2 O, ≥99.0%) was dissolved in 300 ml of deionized water and stirred magnetically for 5 minutes to obtain a uniform solution A. At the same time, 5 mmol potassium hexacyanocobaltate (C 6 CoK 3 N 6 , ≥99.9%) was dissolved in 200 ml of deionized water to form a uniform solution B, and solution B was slowly poured into solution A while stirring evenly. The mixture of solution A and solution B was continuously stirred at an appropriate rate for 10 minutes, and the obtained solution was sealed and aged at room temperature for 12 hours. The obtained solution was centrifuged with water several times until the upper solution became clear to obtain a light blue precipitate. Finally, the precipitate was dried in an oven at 60°C for 12 hours to obtain PBA.

[0050] (2) Synthesis steps of PBA phosphide

[0051] PBA-P powder was prepared by calcination. 2 H 2 6H 2 O, ≥99.0%) powder (500 mg) and PBA powder (100 mg) were evenly dispersed on a quartz boat and transported to the upstream and downstream sides of the tube furnace. The sample was placed in a nitrogen environment and the temperature rise rate was set at 2 °C min -1 , and then calcined at 400°C for 2 hours.

[0052] (3) Synthesis steps of mesoporous carbon-supported NiCo PBA phosphide

[0053] In the process of preparing NiCo PBA, 50 mg of SAC was added when solution A was mixed with solution B, and the other steps remained unchanged, and SAC@PBA was obtained after drying. Similarly, when SAC@PBA-P was prepared by calcination, PBA was replaced by SAC@PBA, and the other preparation conditions were the same as PBA-P.

[0054] Performance Testing

[0055] Figure 1 This is a flow chart for preparing the mesoporous carbon / Prussian blue phosphide composite electrode material of the present invention;

[0056] Figure 2This is the SEM image of the mesoporous carbon-modified Prussian blue phosphide composite electrode material prepared in Example 1, including (a) PBA, (b) SEM images of SAC@PBA-P. The precursor PBA prepared in this experiment has a standard cubic structure, stable structure, smooth surface, no obvious defects, and an average particle size of about 345nm. (b) is the microstructure of SAC@PBA-P, which is similar to the microstructure of PBA at low power. However, by comparison, it can be found that SAC@PBA-P presents an uneven morphology on the original cubic structure, and the overall size is reduced from 345nm to about 150nm. This is due to the decomposition of -CN at 400°C, which causes the occurrence of redox reactions from the outside to the inside, and the continuous consumption of external materials contributes to the formation of this structure.

[0057] Figure 3 TEM images of the preparation and application of a mesoporous carbon / Prussian blue phosphide composite electrode prepared in Example 1, where (a) PBA, (b) SAC@PBA-P, (a) is the cubic structure of PBA, and (b) is the cubic structure of SAC@PBA-P.

[0058] Figure 4 (a) Pore distribution diagram and (b) N2 adsorption / desorption isotherms of the mesoporous carbon-modified Prussian blue phosphide composite electrode materials PBA and SAC@PBA-P prepared in Example 1. The specific surface area of ​​SAC@PBA-P is 63.57 m2 g-1 and the pore volume is 0.106 cm3 g-1, which are lower than 235.58 m2 g-1 and 0.187 cm3 g-1 of PBA.

[0059] Figure 5The test performance of the mesoporous carbon-modified Prussian blue phosphide composite electrode material prepared in Example 1, (a) CC curve (current density is 1Ag-1), (b) CV curve (scan rate is 50mV s-1), (c) specific capacitance, (d) impedance diagram. The electrochemical performance of SAC@PBA-P, (e) CV curve, (f) CC curve, (g) cyclic test capacitance retention and CC curve under the current density set to 12Ag-1, (h) impedance diagram before and after the cyclic test, (i) equivalent circuit diagram, Figure (a) is the CC curve of these electrode materials when the current density is 1A g-1. The specific capacitance of these materials can be obtained by integration: SAC@PBA-P>PBA-P>PBA-S>PBA>PBA-O. In addition, it can be seen that the charging time of PBA-S is significantly longer than that of phosphide, and it is difficult for PBA-S to reach a high potential, which is also the reason why PBA-P doped SAC was finally selected. In Figure (b), all CV curves have obvious redox peaks, and the strong redox peaks undergo deep reactions mainly contributed by multivalent transition metal ions (such as Ni2+ / Ni3+ and Co2+ / Co3+), which illustrates the battery material properties of PBA electrode materials. At a scan rate of 50mV s-1, the CV curves of each sample can be intuitively seen. The CV curves of different materials have different closed areas, and the order of the closed areas is different SAC@PBA-P>PBA-P>PBA-S>PBA>PBA-O. This is consistent with the order of capacitance ratio. Figure (c) shows the comparison of the specific capacitance of all samples at different current densities and shows their multiplication curves. At 1Ag-1, PBA-O is 45.4F g-1, PBA is 184.32F g-1, PBA-S is 741.65F g-1, PBA-P is 855.75F g-1, and SAC@PBA-P is 1097.10F g-1. Different modifications have great improvements. However, the specific capacitance and multiplier performance of PBA-S are significantly lower than those of PBA-P. While maintaining a high multiplier performance, PBA-P improves the specific capacitance performance by about 8 times. Observing the Nyquist curve (d), the Rct values ​​of PBA-P, PBA-S and SAC@PBA-P are all lower than those of PBA. It can be seen from the equivalent circuit diagram of the Nyquist curve (i) that the material resistance can be equivalent to the Rct value in the circuit, and among these samples, the Rct value of PBA-P is the lowest. As shown in Figure (d), the Rct values ​​of PBA, PBA-S, PBA-P and SAC@PBA-P are 14.71, 7.31, 4.13 and 5.33Ω, respectively.

[0060] Figure (ef) shows the 10-50mV s-1CV and 1-5Ag-1 CC curves of SAC@PBA-P. As shown in Figure (e), as the scan rate increases from 10mV s-1 to 50mV s-1, the redox peaks of the CV curve of the material shift to both ends, indicating that the stability of the material decreases at high scan rates. Calculated from Figure (f), the specific capacitance of the material at 1, 2, 3, 4, and 5Ag-1 is 1097.10, 992.49, 885.12, 787.49, and 704.05F g-1, respectively.

[0061] As shown in Figure (g), after 10,000 charge and discharge tests, the capacitance retention rate is still around 47.69%, and the performance degradation is mainly concentrated in the first 2,000 times. As can be seen from Figure (h), after 10,000 cycles, the impedance has only increased slightly and has basically not changed. This proves that the stability of the cubic structure of the material itself is excellent, but the collapse of the agglomerate structure may occur during the charge and discharge process, thereby reducing the effective contact area.

[0062] Similarly, the above-mentioned various performance tests were performed on the mesoporous carbon-modified Prussian blue phosphide composite electrode materials prepared in other embodiments, and the results were similar to the performance of the mesoporous carbon-modified Prussian blue phosphide composite electrode materials prepared in the above Example 3, indicating that the preparation method of the present invention can indeed prepare NiCo-type Prussian blue phosphide composite electrode materials.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the present invention.

Claims

1. A method for preparing and applying a mesoporous carbon / Prussian blue phosphide composite electrode, characterized in that: The preparation method comprises the following steps: (1) First, dissolve sodium citrate and nickel nitrate and stir to obtain a uniform solution A. At the same time, dissolve potassium hexacyanocobaltate in deionized water to form a uniform solution B. Mix solution A and solution B, stir continuously for 10 minutes, seal and age at room temperature for 12 hours. Wash with water several times until the upper solution becomes clear and a light blue precipitate is obtained. Finally, dry the precipitate in an oven at 60°C for 12 hours to obtain PBA. (2) Synthesis steps of PBA oxide, PBA sulfide and PBA phosphide PBA-O powder was prepared by calcination. PBA was heated to 400°C in air and heated at 400°C for 2 hours. PBA-S powder was prepared by hydrothermal method. PBA and sodium sulfate were added to deionized water and stirred magnetically to form a uniform solution. Then, the solution was transferred to a stainless steel autoclave lined with polytetrafluoroethylene and transferred to an oven to be heated. After the reaction was completed, it was washed with deionized water and ethanol and dried to obtain PBA-S. PBA-P powder was prepared by calcination. Monohydrate sodium hypophosphite powder and PBA powder were evenly dispersed on a quartz boat and transported to the upstream and downstream sides of the tube furnace respectively. The sample was placed in a nitrogen environment and then calcined at 400°C for 2 hours. (3) Synthesis steps of mesoporous carbon-supported NiCo PBA phosphide In the process of preparing NiCo PBA, SAC was added when solution A was mixed with solution B, and the other steps remained unchanged, and SAC@PBA was obtained after drying. Similarly, when SAC@PBA-P was prepared by calcination, PBA was replaced by SAC@PBA, and the other preparation conditions were the same as PBA-P.

2. The preparation method according to claim 1, characterized in that: In step (1), the molar ratio of the raw materials is sodium citrate: nickel nitrate: potassium hexacyanocobaltate = 12-24 mmol: 8-16 mmol: 2-5 mmol.

3. The preparation method according to claim 1, characterized in that: In step (1), the solution is sealed and aged at room temperature for 8-16 hours. The obtained solution is washed 2-6 times by centrifugation with water. Finally, the precipitate is dried in an oven at 60-80° C. for 12-16 hours to obtain PBA.

4. PBA-O powder was prepared by calcination. PBA (100-200 mg) was heated in air at 2-5 °C min -1 Heat to 400-600℃, and heat at 400-600℃ for 2-8 hours.

5. PBA-S powder was prepared by a hydrothermal method. PBA (100-200 mg) and 8-12 mmol sodium sulfate (Na2S·9H2O, ≥99.0%) were added to 100-150 ml of deionized water and magnetically stirred for 5-20 minutes to form a uniform solution. Then, the solution was transferred to a stainless steel autoclave lined with polytetrafluoroethylene, transferred to an oven and heated to 70-90°C and maintained for 1-3 hours. After the reaction was completed, it was washed with deionized water and ethanol and centrifuged several times until the solution in the test tube was clear and precipitated. Finally, it was dried at 60-80°C for 12-16 hours to obtain PBA-S.

6. Prepare PBA-P powder by calcination. Disperse monohydrate sodium hypophosphite (NaPO2H2·6H2O, ≥99.0%) powder (500-800 mg) and PBA powder (100-200 mg) evenly on a quartz boat and transport them to the upstream and downstream sides of the tube furnace. Place the sample in a nitrogen environment and set the temperature rise rate to 2-5 °C min -1 , and then continue calcining at 400-500°C for 2-5 hours.

7. In the process of preparing NiCo PBA, 50-100 mg of SAC was added when solution A was mixed with solution B, and the other steps remained unchanged, and SAC@PBA was obtained after drying. Similarly, when SAC@PBA-P was prepared by calcination, PBA was replaced by SAC@PBA, and the other preparation conditions were the same as PBA-P.

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