A Fe-Al single-atom-cluster electrocatalyst, its preparation method and application

Abstract

This invention relates to a Fe-Al single-atom-cluster electrocatalyst, its preparation method, and its application, belonging to the field of electrochemical catalysis technology. The invention uses ferric nitrate as the iron source, sodium aluminate as the aluminum source, and ammonia as the nitrogen source, combining hydrothermal synthesis and chemical vapor deposition (CVD) techniques to prepare a Fe-Al₂O₃ single-atom-cluster catalyst. During the CVD process, ammonia readily decomposes to generate N radicals with lone pairs of electrons, which can efficiently coordinate with Fe ions. The FeN₄ structure and Al₂O₃ clusters are stably connected through oxygen bridges, thereby synthesizing a Fe-Al₂O₃ single-atom-cluster catalyst suitable for alkaline oxygen reduction reactions, possessing low cost, high catalytic activity, and high stability.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical catalysis technology, and specifically relates to a Fe-Al single-atom-cluster electrocatalyst, its preparation method, and its application. Background Technology

[0002] Catalytic reactions are widely used in energy conversion, environmental remediation, and other fields, such as oxygen reduction, CO2 hydrogenation, and methane cracking. Their efficiency and stability directly determine the upper limit of the development of related industries. Currently, traditional precious metal catalysts are difficult to apply on a large scale due to their high cost and scarce resources. Non-precious metal catalysts have become a research focus, among which iron-based catalysts have attracted widespread attention due to their abundant reserves and excellent catalytic activity.

[0003] Pure Fe-based single-atom catalysts have significant application bottlenecks: single-atom Fe active sites are prone to migration and aggregation, leading to the loss of active centers and a significant decrease in catalytic stability; at the same time, the electronic structure of a single Fe active site is difficult to precisely control, resulting in insufficient adsorption-desorption capacity for oxygen-containing intermediates in catalytic reactions, which limits further improvement in catalytic activity and makes it difficult to meet the requirements of high performance and long lifespan for catalysts in practical industrial applications. Summary of the Invention

[0004] The purpose of this invention is to provide a Fe-Al single-atom-cluster electrocatalyst, its preparation method and application, which can solve the technical problem of the difficulty in controlling the coordination structure of single-atom-cluster catalysts;

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A method for preparing a Fe-Al single-atom-cluster electrocatalyst includes the following steps:

[0007] S1. After mixing and stirring the ferric nitrate solution and sodium aluminate solution, the complex solution is mixed with the graphene oxide solution and sonicated using an ultrasonic disperser to obtain a precursor solution; the precursor solution is subjected to a hydrothermal reaction to obtain a black columnar reaction product, wherein the stirring time is 40-60 min and the sonication time is 30-60 min.

[0008] S2. The reaction product was freeze-dried and then subjected to high-temperature nitriding using chemical vapor deposition to obtain an iron-aluminum single-atom-cluster electrocatalyst.

[0009] Preferably, the iron content in the ferric nitrate solution accounts for 3-9% of the mass of graphene oxide in the graphene oxide solution; and the aluminum content in the sodium aluminate solution accounts for 2-6% of the mass of graphene oxide in the graphene oxide solution. The ferric nitrate solution and the sodium aluminate solution are dissolved in deionized water.

[0010] Preferably, the graphene oxide solution is prepared by dispersing graphene oxide solid in deionized water and sonicating for 6-8 h to obtain a graphene oxide solution; the concentration of the graphene oxide solution is 1-6 mg mL-1.

[0011] Preferably, in step S1, the temperature of the hydrothermal reaction is 160-200℃, and the time of the hydrothermal reaction is 10-15h.

[0012] Preferably, in step S2, the freeze-drying process takes 6-15 hours.

[0013] Preferably, in step S2, the high-temperature nitriding using chemical vapor deposition includes the following steps: nitriding is carried out in a mixed atmosphere of argon and ammonia, with a reaction temperature of 800-950 ℃, a reaction time of 1-3 h, an argon flow rate of 100±10 sccm, and an ammonia flow rate of 50±10 sccm.

[0014] In another aspect, the present invention provides an iron-aluminum single-atom-cluster electrocatalyst, which is prepared by the preparation method described above.

[0015] In another aspect, the present invention provides the application of the aforementioned iron-aluminum single-atom-cluster electrocatalyst as a catalyst for the four-electron oxygen reduction reaction to produce water.

[0016] In another aspect, the present invention provides the application of the aforementioned iron-aluminum single-atom-cluster electrocatalyst as a cathode catalyst in a zinc-air battery.

[0017] This invention utilizes ferric nitrate (Fe(NO3)3) as the iron source, sodium aluminate (NaAlO2) as the aluminum source, and ammonia (NH3) as the nitrogen source to synthesize iron-aluminum single-atom-cluster electrocatalysts using a hydrothermal method and chemical vapor deposition (CVD).

[0018] This invention uses graphene oxide as a substrate, and thoroughly stirs and complexes iron ions with aluminate ions to form a stable positively charged complex precursor. After hydrothermal treatment, the iron-aluminum composite structure can be precisely anchored to the defect sites of deprotonated graphene oxide. Then, chemical vapor deposition (CVD) technology is used to control the atomic coordination environment, ultimately preparing iron-aluminum single-atom-cluster electrocatalytic materials. Compared with pure graphene, graphene oxide has more structural defects, which can provide sufficient anchoring sites for metal atoms, effectively inhibiting metal atom aggregation and nanoparticle formation, ensuring the uniform distribution and long-term structural stability of single-atom-cluster active sites. In addition, the precursor formed by metal ions through complexation has good stability. After hydrothermal reaction and high-temperature nitriding treatment, the iron and aluminum bimetals are stably confined on the graphene substrate surface, successfully constructing a stable single-atom-cluster active structure.

[0019] This preparation process is simple and time-efficient, using inexpensive and widely available raw materials. A simple route combining hydrothermal reaction and vapor deposition allows for the efficient preparation of the target catalyst. The resulting iron-aluminum single-atom-cluster catalyst exhibits ideal four-electron oxygen reduction reaction characteristics in an alkaline system, possessing excellent catalytic activity, reaction selectivity, and cycle stability. Its overall catalytic performance is significantly superior to commercial Pt / C catalysts. When applied to zinc-air battery cathode catalytic materials, it can significantly improve the device's power output and cycle life, demonstrating promising prospects for practical industrial applications. Attached Figure Description

[0020] Figure 1 The XRD pattern of the iron-aluminum single-atom-cluster electrocatalyst prepared in Example 1 is shown below.

[0021] Figure 2 The Raman spectrum of the iron-aluminum single-atom-cluster electrocatalyst prepared in Example 1 is shown below.

[0022] Figure 3 The infrared spectrum of the iron-aluminum single-atom-cluster electrocatalyst prepared in Example 1;

[0023] Figure 4 The XRD pattern of the iron-aluminum single-atom-cluster electrocatalyst prepared in Example 2 is shown below.

[0024] Figure 5 The Raman spectrum of the iron-aluminum single-atom-cluster electrocatalyst prepared in Example 2 is shown below.

[0025] Figure 6 The infrared spectrum of the iron-aluminum single-atom-cluster electrocatalyst prepared in Example 2;

[0026] Figure 7 The image shows a TEM image of the iron-aluminum single-atom-cluster electrocatalyst prepared in Example 1, where a-50 nm and b-10 nm are the electrons and aluminum atoms and clusters, respectively.

[0027] Figure 8 XPS fine structure peaks of N 1s and Fe 2p of the iron-aluminum single-atom-cluster electrocatalyst prepared in Example 1, wherein: a-Fe 2p, b-Al 2p, cN 1s, dO 1s;

[0028] Figure 9 The iron-aluminum single-atom-cluster electrocatalyst prepared in Example 1 was used in an alkaline 4e... - The performance of ORR, including: a-polarization curve, b-number of transferred electrons and H2O2 selectivity;

[0029] Figure 10The iron-aluminum single-atom-cluster electrocatalyst prepared in Example 1 was used in an alkaline 4e... - ORR performance, where: a- Tafel slope plot, b- stability curve;

[0030] Figure 11 The discharge polarization curves and power density diagrams of the iron-aluminum single-atom-cluster electrocatalyst prepared in Example 1 are shown in a zinc-air battery device. Detailed Implementation

[0031] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0032] The following examples use the modified Hummers method to prepare graphene oxide. The specific operation includes the following steps: place a three-necked flask in a cold water bath environment, add 3 g of graphite powder and a mixture of concentrated sulfuric acid and phosphoric acid with a volume ratio of 9:1 in sequence, and slowly add 18 g of potassium permanganate at a stirring speed of 200-350 rpm.

[0033] The system was heated to 50 °C and stirred at a constant speed for 12 h. After the reaction, it was cooled to room temperature, and the mixture was slowly poured into 400 mL of pre-cooled deionized water while stirring continuously. Hydrogen peroxide was then slowly added dropwise in portions while stirring until the system turned a stable bright yellow. Subsequently, the system was washed repeatedly with 30% hydrochloric acid, deionized water, anhydrous ethanol, and diethyl ether to remove impurities and residual reagents. Finally, it was dried under vacuum at room temperature for 48 h to obtain pale yellow graphene oxide powder.

[0034] Example 1:

[0035] A method for preparing a Fe-Al2O3 single-atom-cluster catalyst includes the following steps:

[0036] Add 0.16 g of graphene oxide solid to 80 ml of deionized water, sonicate for 6 h, then add a mixture of 6 mL of ferric nitrate nonahydrate solution and 1 mL of sodium aluminate solution to the graphene oxide solution. The iron and aluminum elements account for 6% and 2% of the mass of graphene oxide, respectively. After sonication for 40-60 min, a uniformly dispersed precursor solution is obtained.

[0037] The precursor solution was transferred into the reactor liner, and the hydrothermal temperature was set to 180 °C for 12 h.

[0038] After freeze-drying the hydrothermal product for 12 h, the resulting product was placed in a CVD furnace and subjected to a high-temperature nitridation reaction using chemical vapor deposition in a mixed atmosphere of Ar and NH3. The reaction parameters were set as follows: temperature: 900℃, gas flow rate: NH3: 50 sccm, Ar: 100 sccm, nitridation time: 2 h. A Fe-Al2O3 single-atom-cluster catalyst (Fe-Al2O3-NC-1) was obtained.

[0039] Example 2:

[0040] A method for preparing a Fe-Al2O3 single-atom-cluster catalyst includes the following steps:

[0041] Add 0.16 g of graphene oxide solid to 80 ml of deionized water, sonicate for 6 h, then add a mixture of 3 mL of ferric nitrate nonahydrate solution and 1 mL of sodium aluminate solution to the graphene oxide solution. The mass of iron and aluminum elements account for 3% and 2% of the mass of graphene oxide, respectively. After sonication for 40-60 min, a uniformly dispersed precursor solution is obtained.

[0042] The precursor solution was transferred into the reactor liner, and the hydrothermal temperature was set to 180 °C for 12 h.

[0043] After freeze-drying the hydrothermal product for 12 h, the resulting product was placed in a CVD furnace and subjected to a high-temperature nitridation reaction using chemical vapor deposition in a mixed atmosphere of Ar and NH3. The reaction parameters were set as follows: temperature: 900 ℃, gas flow rate: NH3: 50 sccm, Ar: 100 sccm, nitridation time: 2 h. A Fe-Al2O3 single-atom-cluster catalyst (Fe-Al2O3-NC-2) was obtained.

[0044] Example 3:

[0045] A method for preparing a Fe-Al2O3 single-atom-cluster catalyst includes the following steps:

[0046] Add 0.16 g of graphene oxide solid to 80 ml of deionized water, sonicate for 6 h, then add a mixture of 9 mL of ferric nitrate nonahydrate solution and 1 mL of sodium aluminate solution to the graphene oxide solution. The iron and aluminum elements account for 9% and 2% of the mass of graphene oxide, respectively. After sonication for 40-60 min, a uniformly dispersed precursor solution is obtained.

[0047] The precursor solution was transferred into the reactor liner, and the hydrothermal temperature was set to 180 °C for 12 h.

[0048] After freeze-drying the hydrothermal product for 12 h, the resulting product was placed in a CVD furnace and subjected to a high-temperature nitridation reaction using chemical vapor deposition in a mixed atmosphere of Ar and NH3. The reaction parameters were set as follows: temperature: 900 ℃, gas flow rate: NH3: 50 sccm, Ar: 100 sccm, nitridation time: 2 h. A Fe-Al2O3 single-atom-cluster catalyst (Fe-Al2O3-NC-3) was obtained.

[0049] Example 4:

[0050] A method for preparing a Fe-Al2O3 single-atom-cluster catalyst includes the following steps:

[0051] Add 0.16 g of graphene oxide solid to 80 ml of deionized water, sonicate for 6 h, then add a mixture of 6 mL of ferric nitrate nonahydrate solution and 2 mL of sodium aluminate solution to the graphene oxide solution. The iron and aluminum elements account for 6% and 4% of the mass of graphene oxide, respectively. After sonication for 40-60 min, a uniformly dispersed precursor solution is obtained.

[0052] The precursor solution was transferred into the reactor liner, and the hydrothermal temperature was set to 180 °C for 12 h.

[0053] After freeze-drying the hydrothermal product for 12 h, the resulting product was placed in a CVD furnace and subjected to a high-temperature nitridation reaction using chemical vapor deposition in a mixed atmosphere of Ar and NH3. The reaction parameters were set as follows: temperature: 900 ℃, gas flow rate: NH3: 50 sccm, Ar: 100 sccm, nitridation time: 1.5 h. A Fe-Al2O3 single-atom-cluster catalyst (Fe-Al2O3-NC-4) was obtained.

[0054] Example 5:

[0055] A method for preparing a Fe-Al2O3 single-atom-cluster catalyst includes the following steps:

[0056] Add 0.16 g of graphene oxide solid to 80 ml of deionized water, sonicate for 6 h, then add a mixture of 6 mL of ferric nitrate nonahydrate solution and 3 mL of sodium aluminate solution to the graphene oxide solution. The mass of iron and aluminum elements account for 6% and 6% of the mass of graphene oxide, respectively. After sonication for 40-60 min, a uniformly dispersed precursor solution is obtained.

[0057] The precursor solution was transferred into the reactor liner, and the hydrothermal temperature was set to 180 °C for 12 h.

[0058] After freeze-drying the hydrothermal product for 12 h, the resulting product was placed in a CVD furnace and subjected to a high-temperature nitridation reaction using chemical vapor deposition in a mixed atmosphere of Ar and NH3. The reaction parameters were set as follows: temperature: 900 ℃, gas flow rate: NH3: 50 sccm, Ar: 100 sccm, nitridation time: 2 h. A Fe-Al2O3 single-atom-cluster catalyst (Fe-Al2O3-NC-5) was obtained.

[0059] Example 6:

[0060] A method for preparing a Fe-Al2O3 single-atom-cluster catalyst includes the following steps:

[0061] Add 0.16 g of graphene oxide solid to 80 ml of deionized water, sonicate for 6 h, and then add 6 mL of ferric nitrate nonahydrate solution and 1 mL of sodium aluminate solution to the graphene oxide solution. The iron and aluminum elements account for 6% and 2% of the mass of graphene oxide, respectively. After sonication for 40-60 min, a uniformly dispersed precursor solution is obtained.

[0062] The precursor solution was transferred into the reactor liner, and the hydrothermal temperature was set to 180 °C for 12 h.

[0063] After freeze-drying the hydrothermal product for 12 h, the resulting product was placed in a CVD furnace and subjected to a high-temperature nitridation reaction using chemical vapor deposition in a mixed atmosphere of Ar and NH3. The reaction parameters were set as follows: temperature: 800 ℃, gas flow rate: NH3: 50 sccm, Ar: 100 sccm, nitridation time: 2 h. A Fe-Al2O3 single-atom-cluster catalyst (Fe-Al2O3-NC-6) was obtained.

[0064] Example 7:

[0065] A method for preparing a Fe-Al2O3 single-atom-cluster catalyst includes the following steps:

[0066] Add 0.16 g of graphene oxide solid to 80 ml of deionized water, sonicate for 6 h, and then add 6 mL of ferric nitrate nonahydrate solution and 1 mL of sodium aluminate solution to the graphene oxide solution. The iron and aluminum elements account for 6% and 2% of the mass of graphene oxide, respectively. After sonication for 40-60 min, a uniformly dispersed precursor solution is obtained.

[0067] The precursor solution was transferred into the reactor liner, and the hydrothermal temperature was set to 180 °C for 12 h.

[0068] After freeze-drying the hydrothermal product for 12 h, the resulting product was placed in a CVD furnace and subjected to a high-temperature nitridation reaction using chemical vapor deposition in a mixed atmosphere of Ar and NH3. The reaction parameters were set as follows: temperature: 850 ℃, gas flow rate: NH3: 50 sccm, Ar: 100 sccm, nitridation time: 2 h. A Fe-Al2O3 single-atom-cluster catalyst (Fe-Al2O3-NC-7) was obtained.

[0069] The catalyst performance was evaluated and characterized in the following examples:

[0070] Iron-aluminum single-atom-cluster electrocatalysts were used as catalytic materials for the four-electron oxygen reduction reaction to produce water. Related electrochemical tests were performed using a Pine rotating disk electrode device (including a rotating disk electrode RDE and a rotating ring disk electrode RRDE, electrode model AFE6R2), combined with zinc-air batteries (ZABs).

[0071] The dispersion was prepared as follows: 1 mg of catalyst solid was weighed, and 100 μL of deionized water, 100 μL of anhydrous ethanol, and 20 μL of Nafion solution were added. After mixing thoroughly, the mixture was sonicated for 1 h. 2.5 μL of this dispersion was then drop-coated onto a disk electrode (where the disk area of ​​the RDE is 0.196 cm²). 2 The disk area of ​​RRDE is 0.2376 cm². 2 The area of ​​the matching platinum ring is 0.2356 cm². 2 After the first-coated dispersion has dried, 2.5 μL of the dispersion is then used for a second coating, controlling the areal mass loading of the electrocatalyst to be 0.12 mg cm⁻¹. -2 (RDE) or 0.10 mg cm -2 (RRDE), after natural drying for 12 h, subsequent experimental tests were conducted. A three-electrode system was used: a platinum wire electrode as the counter electrode, an Ag / AgCl electrode with a 3 M potassium chloride solution as the salt bridge as the reference electrode, and a disk electrode or ring-disk electrode coated with an oxygen-bridged iron-aluminum single-atom-cluster electrocatalyst as the working electrode. Before the experiment, nitrogen or oxygen was bubbled into the electrolyte until saturation. The appropriate pH value of the electrolyte was selected according to the experimental requirements (0.1 M KOH for alkaline electrolytes); the initial test was conducted at 100 mV s. -1 The catalyst was activated for about 45 minutes by cyclic voltammetry (CV) at a scan rate of 225-2025 rpm in an oxygen-saturated electrolyte, and linear voltammetry (LSV) was performed at a scan rate of 5 mV s⁻¹ within a voltage range of 0.2-1.1 V.

[0072] The assembly and testing procedures for the zinc-air battery are as follows: For cathode electrode preparation, weigh 5 mg of iron-aluminum single-atom-cluster catalyst and 5 mg of carbon black powder, add 50 μL of isopropanol, 25 μL of polytetrafluoroethylene (PTFE) solution, and 0.95 mL of deionized water, and sonicate for 3-5 hours to ensure uniform dispersion; then drop the resulting dispersion onto a 2.5 × 2.5 cm plate. 2 On hydrophilic carbon paper, the drop coating area was controlled to be 1×1 cm. 2 To ensure that the catalyst loading reaches 1.0 mg cm⁻¹ -2 The anode electrode is a zinc plate. Its surface is first polished clean, then ultrasonically cleaned for 30 minutes each with anhydrous ethanol and acetone to remove surface impurities and oxide layers. The electrolyte used in the battery is a mixed solution of 6 M KOH and 0.2 M ZnCl2.

[0073] Electrochemical tests showed that the catalyst exhibited excellent four-electron oxygen reduction performance under alkaline conditions. The half-wave potential reached 0.870 V, and the current density was 4.62 mA cm⁻¹. -2 It also exhibits good stability and extremely low H2O2 selectivity, fully demonstrating its highly efficient 4-electron ORR catalytic performance.

[0074] Figure 1 The XRD pattern of the iron-aluminum single-atom-cluster electrocatalyst prepared in Example 1 shows that only two characteristic diffraction peaks appear, located near 25° and 44°, corresponding to the (002) and (001) crystal planes of graphene carbon, respectively. No characteristic diffraction peaks of any elemental metal or its compounds were detected in the pattern. This result clearly indicates that the iron and aluminum elements in the catalyst do not form nanoparticles or other aggregated structures, but are uniformly anchored on the graphene substrate surface in the form of single atoms or clusters.

[0075] Figure 2 The image shows the Raman spectrum of the iron-aluminum single-atom-cluster electrocatalyst prepared in Example 1. The D peak (1350 cm⁻¹) is clearly visible in the image. -1 (around) stronger than peak G (1580 cm) -1 (left and right), and the intensity ratio of peak D to peak G (I D / I G The value reached 1.14, which fully demonstrates that the prepared iron-aluminum single-atom-cluster electrocatalyst has abundant structural defects on its surface, exhibiting a significant characteristic of defect enrichment.

[0076] Figure 3 The image shows the infrared spectrum of the iron-aluminum single-atom-cluster electrocatalyst prepared in Example 1. As can be seen from the image, the iron-aluminum single-atom-cluster electrocatalyst has abundant oxygen functional groups.

[0077] Figure 4 The image shows the XRD pattern of the iron-aluminum single-atom-cluster electrocatalyst prepared in Example 2. Only the (002) and (100) crystal planes of graphene were observed, and there were no diffraction peaks of other metals and their compounds. This indicates that after changing the Fe loading, iron and aluminum are still anchored on graphene in the form of single atoms or clusters.

[0078] Figure 5 The image shows the Raman spectrum of the iron-aluminum single-atom-cluster electrocatalyst prepared in Example 2. The intensity ratio of the D peak to the G peak (I) is shown. D / I G The value reached 1.08, indicating that the prepared iron-aluminum single-atom-cluster electrocatalyst was defect-enriched, and the degree of defect increased with increasing iron content.

[0079] Figure 6 The infrared spectrum of the iron-aluminum single-atom-cluster electrocatalyst prepared in Example 2 is shown, which also illustrates that the catalyst has abundant oxygen-containing functional groups.

[0080] Figure 7 a and Figure 7 b are low-magnification and high-magnification TEM images of the iron-aluminum single-atom-cluster electrocatalyst prepared in Example 1, respectively. It can be clearly seen from the two images that the prepared iron-aluminum single-atom-cluster electrocatalyst has a large number of rich wrinkled structures on its surface. These wrinkled structures can effectively increase the specific surface area of ​​the catalyst, which is beneficial for exposing more catalytic active sites, thus providing favorable conditions for the smooth progress of the electrochemical reaction.

[0081] Figure 8 The image shown is the XPS plot of the oxygen-bridged iron-aluminum single-atom-cluster electrocatalyst prepared in Example 1, wherein... Figure 8 The Fe 2p spectrum of a shows that Fe in the iron-aluminum single-atom-cluster electrocatalyst... 2+ with Fe 3+ Mixed existence, Figure 8 b represents the Al 2p orbital in the iron-aluminum single-atom-cluster electrocatalyst. Figure 8 The N 1s spectrum of c shows characteristic peaks near 398.2, 399.4, 400.2, 401.5, and 403.5 eV, which are attributed to pyridine nitrogen, iron nitrogen, pyrrole nitrogen, graphitic nitrogen, and nitrogen oxide components, respectively; among them, pyridine nitrogen and iron nitrogen components favor 4e... – The ORR reaction proceeds. Figure 8 In the fine 1s spectrum of d, characteristic peaks near 530.1-530.9, 531.5, 533.4 and 533.9 eV can be identified as Fe-O / Al-O, C=O, CO and C-OH, respectively.

[0082] Figure 9 The image shows the iron-aluminum single-atom-cluster electrocatalyst prepared in Example 1 under alkaline 4e conditions. - ORR performance, among which Figure 9 a and Figure 9 b are polarization curves in 0.1 M KOH electrolyte, where the catalyst has a high half-wave potential (E0). 1 / 2 0.870 V) and limiting current density (J D 4.62 mA cm -2 The electron transfer number (n) was 3.92 and the H2O2 selectivity was 5.6%, both of which indicate that the catalyst is an ideal four-electron transfer pathway under alkaline conditions.

[0083] Figure 10 The image shows the iron-aluminum single-atom-cluster electrocatalyst prepared in Example 1 under alkaline 4e conditions. - ORR performance, among which Figure 10 a and Figure 10 b represents the Tafel slope and stability curve in 0.1 M KOH electrolyte, respectively. The calculated Tafel slope is 109 mV dec. -1 This indicates that the catalyst possesses superior kinetic performance and maintains high stability during continuous operation for up to 25 hours, with no significant decrease in current density (93%). In summary, the iron-aluminum single-atom-cluster electrocatalyst exhibits excellent 4e-ion conductivity under alkaline conditions. - ORR activity and stability.

[0084] Figure 11 The figure shows the discharge polarization curve and power density diagram of the iron-aluminum single-atom-cluster electrocatalyst prepared in Example 1 under a zinc-air battery device, which can reach 135 mW cm⁻¹. -2 Peak power density, with superior power density and stability.

Claims

1. A method for preparing a Fe-Al single-atom-cluster electrocatalyst, characterized in that, Includes the following steps: S1. After stirring the iron source and aluminum source, mix the mixed solution with the graphene oxide solution and sonicate to obtain the precursor solution; The precursor solution was subjected to a hydrothermal reaction to obtain the reaction product; S2. The reaction product was freeze-dried and then subjected to high-temperature nitriding using chemical vapor deposition to obtain an iron-aluminum single-atom-cluster electrocatalyst.

2. The preparation method according to claim 1, characterized in that, The percentage of iron in the iron source relative to the mass of graphene oxide in the graphene oxide solution is 3-9%; the percentage of aluminum in the aluminum source relative to the mass of graphene oxide in the graphene oxide solution is 2-6%.

3. The preparation method according to claim 1 or 2, characterized in that, The iron source is ferric nitrate; the aluminum source is sodium aluminate.

4. The preparation method according to claim 1, characterized in that, In step S1, the graphene oxide solution is prepared by dispersing solid graphene oxide in deionized water and sonicating for 6-8 hours to obtain a graphene oxide solution; the concentration of the graphene oxide solution is 1-6 mg / mL. -1 .

5. The preparation method according to claim 1, characterized in that, In step S1, the temperature of the hydrothermal reaction is 160-200℃, and the reaction time is 10-15 h.

6. The preparation method according to claim 1, characterized in that, In step S2, the freeze-drying process takes 6-15 hours.

7. The preparation method according to claim 1, characterized in that, In step S2, the high-temperature nitriding using chemical vapor deposition includes the following steps: nitriding is carried out in a mixed atmosphere of argon and ammonia, with a reaction temperature of 800-950℃, a reaction time of 1-3 h, an argon flow rate of 100±10 sccm, and an ammonia flow rate of 50±10 sccm.

8. A Fe-Al single-atom-cluster electrocatalyst, prepared by the preparation method according to any one of claims 1-7.

9. The application of the Fe-Al single-atom-cluster electrocatalyst according to claim 8 as a catalyst for the four-electron oxygen reduction reaction to produce water.

10. The application of the Fe-Al single-atom-cluster electrocatalyst according to claim 8 as a cathode catalyst in a zinc-air battery.

Images