Preparation method and application of n, p co-doped fe-based electrocatalyst

Abstract

The application relates to a preparation method of an N, P co-doped Fe-based electrocatalyst and application thereof. The preparation method of the embodiment comprises the following steps: preparing a mixture of FeN2P1 metal organic complex, a carbon carrier and dicyanodiamine; and baking the mixture under an inert atmosphere, wherein the baking process comprises the following steps: firstly, heating to 500-550 DEG C and keeping for 1-3 hours, and then heating to 700-900 DEG C and keeping for 1-3 hours, so as to obtain the N, P co-doped Fe-based electrocatalyst. The Fe-based electrocatalyst prepared by the application has excellent catalytic activity and stability for ORR and OER reactions.

Description

Technical Field

[0001] This invention relates to the field of non-precious metal electrocatalysts; more specifically, it relates to a method for preparing an N, P co-doped Fe-based electrocatalyst and its application. Background Technology

[0002] With the global pursuit of alternatives to non-renewable energy sources such as petroleum fossils, clean and sustainable energy conversion devices such as fuel cells and metal-air batteries with high theoretical energy density are considered promising alternatives. The sluggish kinetics of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are bottlenecks that hinder the performance of these batteries, making the development of high-performance ORR and OER catalysts particularly critical.

[0003] Currently, platinum-based catalysts, ruthenium oxide, and iridium oxide, which utilize precious metals, remain the most promising catalysts for commercial applications in ORR and OER. However, the high cost and scarcity of precious metals mean that most of the cost in commercially available batteries is concentrated on precious metal catalysts, severely hindering the commercial development of batteries. Therefore, it is urgent to shift the focus to researching non-precious metal catalysts that are low-cost and naturally abundant.

[0004] Existing research indicates that heteroatom doping, such as with nitrogen (N), sulfur (S), and phosphorus (P), is an effective method to improve the ORR and OER activities of non-noble metal catalysts. However, in current technologies, heteroatom doping typically uses precursors separate from the metal, meaning the metal and heteroatom precursors are independent of each other. For example, in the preparation of Fe-based non-noble metal catalysts, ferric nitrate or ferric chloride are used as the Fe source, triphenylphosphine as the P source, and thiourea as the S source. In these preparation methods, Fe and heteroatoms are not pre-coordinated, resulting in a complex form of Fe. Taking P doping as an example, the final catalyst may contain zero-valent Fe particles, Fe2P, Fe3P, FeP, etc., which not only makes it more difficult to study the structure-activity relationship of the catalytic reaction but also makes it difficult to obtain specific reaction selectivity, leading to more side reactions and thus limiting the improvement of catalytic activity. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the main objective of this invention is to provide a method for preparing N, P co-doped Fe-based electrocatalysts. The catalyst prepared by this method has Fe in a phase that is primarily Fe2P, resulting in catalysts with extremely high ORR and OER catalytic activity and stability.

[0006] To achieve the above-mentioned main objectives, the method for preparing the N, P co-doped Fe-based catalyst provided by this invention includes the following steps:

[0007] A mixture of FeN2P1 organometallic complex, carbon support, and dicyandiamine was prepared.

[0008] The above mixture was calcined under an inert atmosphere. During the calcination process, the temperature was first raised to 500-550℃ and held for 1-3 hours, and then raised to 700-900℃ and held for 1-3 hours to obtain an N, P co-doped Fe-based electrocatalyst.

[0009] The structural formula of the FeN2P1 organometallic complex is as follows:

[0010]

[0011] According to a specific embodiment of the present invention, the above-mentioned FeN2P1 organometallic complex is obtained by the following method:

[0012] Cyclohexanediamine and diphenylphosphine benzaldehyde were added to the reaction vessel in a predetermined molar ratio, and an appropriate amount of anhydrous ethanol was added as a solvent. The mixture was then refluxed under an inert atmosphere at 85–99 °C for 10–24 hours.

[0013] Ferric chloride was added, and the reaction was refluxed for 10–24 hours. Anhydrous ethanol was then removed from the reaction mixture to obtain the FeN2P1 organometallic complex.

[0014] In the above technical solution, the molar ratio of cyclohexanediamine to diphenylphosphine benzaldehyde is preferably greater than or equal to 1, more preferably 1 to 1.5:1, for example 1.2:1.

[0015] In the above technical solution, the molar ratio of ferric chloride and diphenylphosphine benzaldehyde is preferably 1:1.

[0016] According to a specific embodiment of the present invention, FeN2P1 metal-organic complex, carbon support and dicyandiamine are mixed evenly by grinding, and ethanol is added as a dispersant during the grinding process.

[0017] According to one specific embodiment of the present invention, the carbon carrier is carbon black.

[0018] According to a specific embodiment of the present invention, the mass ratio of FeN2P1 organometallic complex, carbon support and dicyandiamine in the mixture is 1-5:5:200-400.

[0019] According to one specific embodiment of the present invention, during the roasting process, the temperature is increased to 500℃ to 550℃ at a heating rate of 2℃ / min to 3℃ / min, and then increased to 700℃ to 900℃ at a heating rate of 5℃ / min to 10℃ / min.

[0020] This invention also relates to the application of the N, P co-doped Fe-based electrocatalyst obtained by the above preparation method in ORR and OER reactions.

[0021] The present invention has the following beneficial effects:

[0022] (1) Metallic Fe and heteroatom P use a common precursor, FeN2P1, a metal-organic complex. The use of this precursor ensures that the Fe phase in the catalyst is basically Fe2P and does not contain elemental Fe, which makes the catalyst have excellent electrocatalytic activity and stability for ORR and OER reactions.

[0023] (2) At a calcination temperature of 500℃~550℃, dicyandiamine decomposes to generate g-C3N4. g-C3N4 contains abundant pyridine-like N atoms and has a strong coordination ability. Therefore, it can coordinate and anchor with Fe in FeN2P1, preventing the migration and aggregation of metallic Fe. This results in Fe2P being evenly distributed on the carbon support, forming more active sites, and further promoting the improvement of catalytic performance.

[0024] (3) During the roasting process, dicyandiamine is used as a nitrogen source to achieve N doping of the carbon support. The synthesis method is simple and has few steps.

[0025] To more clearly illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0026] Figure 1 This is a flowchart of an embodiment of the catalyst preparation method of the present invention;

[0027] Figure 2 The XRD characterization pattern of the FeN2P1 / CN catalyst prepared in Example 1 is shown below.

[0028] Figure 3 The XRD characterization spectra of the Fe / CN catalysts prepared in the comparative proportions are shown below.

[0029] Figure 4 Here is a SEM image of the FeN2P1 / CN catalyst prepared in the examples;

[0030] Figure 5 These are SEM images of the Fe / CN catalysts prepared in the comparative proportions.

[0031] Figure 6 This is a comparison of the linear sweep voltammetric curves (LSV) of the ORR of FeN2P1 / CN catalyst, Fe / CN catalyst, P / CN catalyst, CN catalyst prepared in the examples and comparative examples with those of commercial Pt / C.

[0032] Figure 7This is a comparison of the linear sweep voltammetry (LSV) curves of the OER of the FeN2P1 / CN catalyst prepared in the examples and the Fe / CN catalyst prepared in the comparative examples.

[0033] Figure 8 The image shows the open-circuit voltage measured with a multimeter after the FeN2P1 / CN catalyst prepared in the example was used as an air electrode to assemble a zinc-air battery.

[0034] Figure 9 The graph shows the open-circuit voltage data measured by an electrochemical workstation after the FeN2P1 / CN catalyst prepared in the example was used as an air electrode to assemble a zinc-air battery.

[0035] Figure 10 The charge-discharge curves and power density diagrams were measured after the FeN2P1 / CN catalyst prepared in the examples was used as an air electrode to assemble a zinc-air battery.

[0036] Figure 11 The charge-discharge cycle stability diagram is obtained after assembling a zinc-air battery using the FeN2P1 / CN catalyst prepared in the example as an air electrode.

[0037] Figure 12 This is a comparison chart of ORR LSV of the catalysts prepared in Examples 1-3 and commercial Pt / C catalysts;

[0038] Figure 13 This is a comparison chart of the ORR LSV of the catalysts prepared in Examples 1, 4 and 5. Detailed Implementation

[0039] This invention provides a method for preparing an N, P co-doped Fe-based catalyst, wherein the main Fe phase in the catalyst obtained by this method is Fe₂P. Figure 1 As shown, the preparation method of the embodiment includes the following steps:

[0040] (1) Cyclohexanediamine and diphenylphosphine benzaldehyde were added to a three-necked flask at a molar ratio of 1 to 1.5:1. Anhydrous ethanol was used as the reaction solvent. The mixture was refluxed at 85°C to 99°C for 10 to 24 hours under a nitrogen atmosphere. Then, ferric chloride hexahydrate was added in an equal molar amount to diphenylphosphine benzaldehyde. The mixture was refluxed at 85°C to 99°C for another 10 to 24 hours. After the reaction was completed, the solvent was removed by rotary evaporation to obtain a blood-red solid, which was a FeN2P1 organometallic complex.

[0041] The reaction that occurred in step (1) and the structure of the resulting FeN2P1 organometallic complex are as follows:

[0042]

[0043] (2) The synthesized FeN2P1 organometallic complex, ultra-high conductivity carbon black BP2000, and dicyandiamine are placed in a mortar, and an appropriate amount of ethanol is added as a co-solvent and dispersant. The mixture is then ground evenly to obtain a dark gray solid mixture. The FeN2P1 organometallic complex, carbon black BP2000, and dicyandiamine can be fed in a mass ratio of x:5:y (where x ranges from 1 to 5 and y ranges from 200 to 400).

[0044] (3) The mixture obtained in the previous step is placed in a tube furnace and calcined at high temperature under a nitrogen atmosphere to obtain the catalyst FeN2P1 / CN. The specific heating program is to heat to 500-550℃ at a heating rate of 2℃ / min to 3℃ / min to promote the decomposition of dicyandiamine to generate g-C3N4. After holding at 500-550℃ for 1-3 hours, the temperature is increased to 700-900℃ at a heating rate of 5℃ / min to 10℃ / min and held for 1-3 hours.

[0045] The present invention will now be described in more detail with reference to specific embodiments and comparative examples.

[0046] Example 1 Preparation of FeN2P1 / CN catalyst

[0047] Cyclohexanediamine (3.8 mmol, 422.9 mg) and diphenylphosphine benzaldehyde (3.8 mmol, 1010 mg) were added to a three-necked flask. After purging the air with nitrogen, 120 mL of anhydrous ethanol was added. The mixture was refluxed at 90 °C for 24 hours under a nitrogen atmosphere. Then, ferric chloride hexahydrate (3.8 mmol, 1026 mg) was added, and the mixture was refluxed at 90 °C for another 24 hours. After the reaction was completed, the solvent was removed by rotary evaporation to obtain a blood-red solid, which was a FeN2P1 organometallic complex.

[0048] The FeN2P1 organometallic complex (84 mg) synthesized in the previous step was placed in a mortar with ultra-high conductivity carbon black BP2000 (150 mg) and dicyandiamine (6 g), and 10 mL of ethanol was added as a co-solvent and dispersant. The mixture was ground for 2 hours to obtain a dark gray solid mixture.

[0049] The mixture obtained in the previous step was placed in a tube furnace and heated to 550°C at a heating rate of 2.5°C / min under a nitrogen atmosphere. The temperature was held for 2 hours, and then heated to 800°C at a heating rate of 5°C / min and held for 2 hours to obtain the catalyst FeN2P1 / CN.

[0050] Example 2 Preparation of FeN2P1 / CN-700 catalyst

[0051] Cyclohexanediamine (3.8 mmol, 422.9 mg) and diphenylphosphine benzaldehyde (3.8 mmol, 1010 mg) were added to a three-necked flask. After purging the air with nitrogen, 120 mL of anhydrous ethanol was added. The mixture was refluxed at 90 °C for 24 hours under a nitrogen atmosphere. Then, ferric chloride hexahydrate (3.8 mmol, 1026 mg) was added, and the mixture was refluxed at 90 °C for another 24 hours. After the reaction was completed, the solvent was removed by rotary evaporation to obtain a blood-red solid, which was a FeN2P1 organometallic complex.

[0052] The FeN2P1 organometallic complex (84 mg) synthesized in the previous step was placed in a mortar with ultra-high conductivity carbon black BP2000 (150 mg) and dicyandiamine (6 g), and 10 mL of ethanol was added as a co-solvent and dispersant. The mixture was ground for 2 hours to obtain a dark gray solid mixture.

[0053] The mixture obtained in the previous step was placed in a tube furnace and heated to 550°C at a heating rate of 2.5°C / min under a nitrogen atmosphere. The temperature was held for 2 hours, and then heated to 700°C at a heating rate of 5°C / min and held for 2 hours to obtain the catalyst FeN2P1 / CN-700.

[0054] Example 3 Preparation of FeN2P1 / CN-900 catalyst

[0055] Cyclohexanediamine (3.8 mmol, 422.9 mg) and diphenylphosphine benzaldehyde (3.8 mmol, 1010 mg) were added to a three-necked flask. After purging the air with nitrogen, 120 mL of anhydrous ethanol was added. The mixture was refluxed at 90 °C for 24 hours under a nitrogen atmosphere. Then, ferric chloride hexahydrate (3.8 mmol, 1026 mg) was added, and the mixture was refluxed at 90 °C for another 24 hours. After the reaction was completed, the solvent was removed by rotary evaporation to obtain a blood-red solid, which was a FeN2P1 organometallic complex.

[0056] The FeN2P1 organometallic complex (84 mg) synthesized in the previous step was placed in a mortar with ultra-high conductivity carbon black BP2000 (150 mg) and dicyandiamine (6 g), and 10 mL of ethanol was added as a co-solvent and dispersant. The mixture was ground for 2 hours to obtain a dark gray solid mixture.

[0057] The mixture obtained in the previous step was placed in a tube furnace and heated to 550°C at a heating rate of 2.5°C / min under a nitrogen atmosphere. The temperature was held for 2 hours, and then heated to 900°C at a heating rate of 5°C / min and held for 2 hours to obtain the catalyst FeN2P1 / CN-900.

[0058] Example 4 Preparation of FeN2P1 / CN-2C catalyst

[0059] Cyclohexanediamine (3.8 mmol, 422.9 mg) and diphenylphosphine benzaldehyde (3.8 mmol, 1010 mg) were added to a three-necked flask. After purging the air with nitrogen, 120 mL of anhydrous ethanol was added. The mixture was refluxed at 90 °C for 24 hours under a nitrogen atmosphere. Then, ferric chloride hexahydrate (3.8 mmol, 1026 mg) was added, and the mixture was refluxed at 90 °C for another 24 hours. After the reaction was completed, the solvent was removed by rotary evaporation to obtain a blood-red solid, which was a FeN2P1 organometallic complex.

[0060] The FeN2P1 organometallic complex (84 mg) synthesized in the previous step was placed in a mortar with BP2000 (300 mg) of ultra-high conductivity carbon black and dicyandiamine (6 g), 10 mL of ethanol was added as a co-solvent and dispersant, and the mixture was ground for 2 hours to obtain a dark gray solid mixture.

[0061] The mixture obtained in the previous step was placed in a tube furnace and heated to 550°C at a heating rate of 2.5°C / min under a nitrogen atmosphere. The temperature was held for 2 hours, and then heated to 800°C at a heating rate of 5°C / min and held for 2 hours to obtain the catalyst FeN2P1 / CN-2C.

[0062] Example 5 Preparation of FeN2P1 / CN-2N catalyst

[0063] Cyclohexanediamine (3.8 mmol, 422.9 mg) and diphenylphosphine benzaldehyde (3.8 mmol, 1010 mg) were added to a three-necked flask. After purging the air with nitrogen, 120 mL of anhydrous ethanol was added. The mixture was refluxed at 90 °C for 24 hours under a nitrogen atmosphere. Then, ferric chloride hexahydrate (3.8 mmol, 1026 mg) was added, and the mixture was refluxed at 90 °C for another 24 hours. After the reaction was completed, the solvent was removed by rotary evaporation to obtain a blood-red solid, which was a FeN2P1 organometallic complex.

[0064] The FeN2P1 organometallic complex (84 mg) synthesized in the previous step was placed in a mortar with ultra-high conductivity carbon black BP2000 (150 mg) and dicyandiamine (12 g), and 10 mL of ethanol was added as a co-solvent and dispersant. The mixture was ground for 2 hours to obtain a dark gray solid mixture.

[0065] The mixture obtained in the previous step was placed in a tube furnace and heated to 550°C at a heating rate of 2.5°C / min under a nitrogen atmosphere. The temperature was held for 2 hours, and then heated to 800°C at a heating rate of 5°C / min and held for 2 hours to obtain the catalyst FeN2P1 / CN-2N.

[0066] Comparative Example 1: Preparation of Fe / CN catalyst

[0067] The difference between this comparative example and Example 1 is that the Fe source used in this comparative example is FeCl3·6H2O, which does not contain P. Therefore, the catalyst in this comparative example is not doped with P. The specific steps are as follows:

[0068] FeCl3·6H2O (42 mg), ultra-high conductivity carbon black BP2000 (150 mg), and dicyandiamine (6000 mg) were placed in a mortar, and 10 mL of ethanol was added as a co-solvent and dispersant. The mixture was ground for 2 hours to obtain a dark gray solid mixture.

[0069] The mixture obtained in the previous step was placed in a tube furnace and heated to 550°C at a heating rate of 2.5°C / min under a nitrogen atmosphere. The temperature was held for 2 hours, and then heated to 800°C at a heating rate of 5°C / min and held for 2 hours to obtain the comparative Fe / CN catalyst.

[0070] Comparative Example 2: Preparation of P / CN Catalyst

[0071] The difference between Comparative Example 2 and Example 1 is that no Fe source was used. The specific steps are as follows:

[0072] Triphenylphosphine benzaldehyde (45 mg), ultra-high conductivity carbon black BP2000 (150 mg), and dicyandiamine (6000 mg) were placed in a mortar, and 10 mL of ethanol was added as a co-solvent and dispersant. The mixture was ground for 2 hours to obtain a dark gray solid mixture.

[0073] The mixture obtained in the previous step was placed in a tube furnace and heated to 550°C at a heating rate of 2.5°C / min under a nitrogen atmosphere. The temperature was held for 2 hours, and then heated to 800°C at a heating rate of 5°C / min and held for 2 hours to obtain the control sample P / CN catalyst.

[0074] Comparative Example 3: Preparation of CN catalyst

[0075] The difference between Comparative Example 3 and Example 1 is that Fe and P sources were not used. The specific steps are as follows:

[0076] BP2000 ultra-high conductivity carbon black (150 mg) and dicyandiamine (6000 mg) were placed in a mortar, and 10 mL of ethanol was added as a co-solvent and dispersant. The mixture was ground for 2 hours to obtain a dark gray solid mixture.

[0077] The mixture obtained in the previous step was placed in a tube furnace and heated to 550°C at a heating rate of 2.5°C / min under a nitrogen atmosphere. The temperature was held for 2 hours, and then heated to 800°C at a heating rate of 5°C / min and held for 2 hours to obtain the comparative CN catalyst.

[0078] Phase and morphology analysis of the examples and comparative examples

[0079] Figure 2 The image shows the XRD pattern of the FeN2P1 / CN catalyst prepared in Example 1. By comparing it with the PDF card, it can be seen that the Fe phase in this catalyst is basically Fe2P. Figure 3 The XRD pattern of the Fe / CN catalyst prepared in Comparative Example 1 is shown. By comparing with the PDF card, it can be seen that the main Fe phases in this catalyst are Alpha-Fe and Gamma-Fe. Figure 4 The image shows the FE-SEM image of the FeN2P1 / CN catalyst prepared in Example 1. As can be seen from the image, the catalyst has a particulate structure with carbon microspheres having a particle size of less than 100 nm. Figure 5 The image shows a SEM image of the Fe / CN catalyst prepared in Comparative Example 1. As can be seen from the image, the structure of this catalyst is significantly different from that of the catalyst in the example, and this catalyst has a large number of carbon nanotubes.

[0080] Studies have shown that the presence of elemental Fe promotes the Fenton effect, leading not only to increased hydrogen peroxide yield and decreased oxygen reduction electron transfer efficiency, but also to the formation of harmful peroxide intermediates, which etch carbon materials and reduce catalyst stability. In the catalyst prepared in this invention, the Fe phase is primarily Fe₂P, without elemental Fe, resulting in excellent electrocatalytic activity and stability for both ORR and OER reactions. In contrast, if different precursors are used for Fe and P according to existing technologies, calcination inevitably leads to the formation of elemental Fe, which degrades catalytic performance.

[0081] Catalytic performance test of the example

[0082] ORR testing conditions: A rotating disk electrode was used at a speed of 1600 rpm, and the catalyst loading was 0.6 mg / cm³. -2 The test was conducted using a three-electrode system in an O2-saturated 0.1 mol / L KOH solution; the reference electrode was an Ag / AgCl electrode, and the counter electrode was a platinum electrode.

[0083] OER testing conditions: The working electrode was prepared by dropping catalyst ink onto a 1*1 cm nickel foam, with a catalyst loading of 0.6 mg / cm³. -2 The test was conducted in a 1.0 mol / L KOH solution using a three-electrode system; the reference electrode was an Ag / AgCl electrode, and the counter electrode was a platinum electrode.

[0084] Zinc-air battery test: using a zinc sheet as the anode, loaded with 0.6 mg cm⁻¹ -2The catalyst uses carbon paper as the air cathode, and the electrolyte is a mixture of 6.0 mol / L KOH and 0.2 mol / L ZnAc.

[0085] in, Figure 6 and 7 All potentials in the diagram are the converted standard hydrogen electrode potentials.

[0086] Figure 6 This is a comparison of the ORR linear sweep voltammetry (LSV) curves of the FeN2P1 / CN catalyst, Fe / CN catalyst, P / CN catalyst, and CN catalyst prepared in Example 1 and the comparative examples. Figure 6 It can be intuitively seen that the onset potential and half-wave potential of the FeN2P1 / CN catalyst in the examples are significantly higher than those of the comparative catalyst and the commercial Pt / C, indicating the excellent ORR performance of the FeN2P1 / CN catalyst.

[0087] Figure 7 This is a comparison of the OER linear sweep voltammetry (LSV) curves of the FeN2P1 / CN catalyst prepared in Example 1 and the Fe / CN catalyst prepared in Comparative Example 1. From... Figure 7 It can be visually observed that the FeN2P1 / CN catalyst of Example 1 exhibits better performance at 50 mA cm⁻¹. -2 The potential at the current density was 1.551V, which was 67mV lower than the 1.618V of the Fe / CN catalyst prepared in the comparative example, indicating the excellent OER performance of the FeN2P1 / CN catalyst.

[0088] Figure 8 and Figure 9 The images show optical images of the open-circuit voltage measured with a multimeter and data graphs of the open-circuit voltage measured with an electrochemical workstation after the FeN2P1 / CN catalyst prepared in Example 1 was assembled into a zinc-air battery using an air electrode. As can be seen from the figures, the open-circuit voltage of the assembled battery is 1.5V, which is close to the theoretical open-circuit voltage, indicating that the battery has good reversibility. This further indicates that the FeN2P1 / CN catalyst has good bifunctional electrocatalytic activity.

[0089] Figure 10 The graph shows the charge-discharge curves and power density of a zinc-air battery assembled using the FeN2P1 / CN catalyst prepared in Example 1 as an air electrode. The graph shows that the peak power density of the battery is 112 mW / cm². -2 .

[0090] Figure 11The figure shows the charge-discharge cycle stability of a zinc-air battery assembled using the FeN2P1 / CN catalyst prepared in Example 1 as an air electrode. As can be seen from the figure, the battery exhibits excellent stability, with no performance degradation even after 37 hours of cycling. This indicates that the FeN2P1 / CN catalyst has promising application prospects in zinc-air batteries.

[0091] Figure 12 This is a comparison of the ORR LSV of the catalysts prepared in Examples 1-3 with those of commercial Pt / C. As can be seen from the figure, the catalysts prepared in Examples 1-3 all exhibit superior catalytic performance compared to commercial Pt / C, with the catalyst in Example 1 showing the best performance, indicating that a calcination temperature of 800℃ is the optimal synthesis condition.

[0092] Figure 13 This is a comparison graph of the ORR LSV of the catalysts prepared in Examples 1, 4, and 5. As can be seen from the graph, adjusting the amount of BP2000 or dicyandiamide within an appropriate range has almost no impact on the performance of the catalyst.

[0093] The commercial Pt / C catalyst used as a comparative object in this invention was purchased from Johnson Matthey.

[0094] Although the present invention has been described above through specific embodiments, it should be understood that any equivalent improvements made by those skilled in the art in accordance with the present invention without departing from the scope of the present invention should be covered by the protection scope of the present invention.

Claims

1. A method for preparing an N, P co-doped Fe-based electrocatalyst, comprising the following steps: A mixture of FeN2P1 organometallic complex, carbon support, and dicyandiamine was prepared. The mixture was calcined under an inert atmosphere. During the calcination process, the temperature was first raised to 500-550°C and held for 1-3 hours, and then raised to 700-900°C and held for 1-3 hours to obtain an N, P co-doped Fe-based electrocatalyst. in, The structural formula of the FeN2P1 organometallic complex is as follows:

2. The preparation method according to claim 1, wherein, The FeN2P1 organometallic complex was obtained by the following method: Cyclohexanediamine and diphenylphosphine benzaldehyde were added to the reaction vessel in a predetermined molar ratio, and an appropriate amount of anhydrous ethanol was added as a solvent. The mixture was then refluxed under an inert atmosphere at 85–99 °C for 10–24 hours. Ferric chloride was added, and the reaction was refluxed for 10–24 hours. Anhydrous ethanol was then removed from the reaction mixture to obtain the FeN2P1 organometallic complex.

3. The preparation method according to claim 2, wherein, The molar ratio of the cyclohexanediamine to the diphenylphosphine benzaldehyde is 1 to 1.5:

1.

4. The preparation method according to claim 2, wherein, The molar ratio of ferric chloride to diphenylphosphine benzaldehyde is 1:

1.

5. The preparation method according to claim 1, wherein, The FeN2P1 metal-organic complex, the carbon support, and the dicyandiamine were mixed evenly using a grinding method, with ethanol added as a dispersant during the grinding process.

6. The preparation method according to claim 1, wherein, The carbon carrier is carbon black.

7. The preparation method according to claim 1, wherein, The mass ratio of FeN2P1 organometallic complex, carbon support, and dicyandiamine in the mixture is 1–5:5:200–400.

8. The preparation method according to claim 1, wherein, During the roasting process, the temperature is increased to 500℃ to 550℃ at a heating rate of 2℃ / min to 3℃ / min, and then increased to 700℃ to 900℃ at a heating rate of 5℃ / min to 10℃ / min.

9. The application of the N, P co-doped Fe-based electrocatalyst obtained by any one of claims 1 to 8 in the ORR reaction.

10. The application of the N, P co-doped Fe-based electrocatalyst obtained by any one of claims 1 to 8 in the OER reaction.

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