A porous carbon supported transition metal composite material, a preparation method and application thereof

Abstract

The application belongs to the technical field of battery materials, and discloses a porous carbon loaded transition metal composite material and a preparation method and application thereof. A novel catalyst is manufactured by a simple pyrolysis method, the catalyst comprises atomically dispersed Fe monomers and FeSe nanoparticles which are co-grown on N-doped carbon (nanosheets). Due to the mutual cooperation between the Fe monomers and the FeSe nanoparticles, the catalyst has stronger reactant adsorption capacity and lower dissociation energy barrier, can effectively reduce the adsorption energy and synergistically improve the catalytic activity, has excellent catalytic performance, and is superior to a commonly used Pt / C catalyst on the market in performance.

Description

Technical Field

[0001] This invention belongs to the field of battery materials technology, and specifically relates to a porous carbon-supported transition metal composite material, its preparation method and application. Background Technology

[0002] In recent years, with increasing global attention to climate change and sustainable development, the demand for clean and renewable energy sources has become more urgent. Metal-air batteries, as a highly efficient and green energy conversion technology, directly convert chemical energy into electrical energy through electrochemical pathways, demonstrating unique advantages such as low cost, zero pollution, and high energy density, indicating broad application potential in the field of energy storage. However, the oxygen reduction reaction (ORR), a core step in this technology and fuel cells, suffers from sluggish kinetics, becoming a bottleneck for development. Although platinum-based catalysts are widely used in air electrodes due to their high activity, high temperature resistance, and resistance to oxygen and corrosion, their high cost, resource scarcity, and insufficient durability limit their practicality. Furthermore, traditional catalysts have limitations in terms of atom utilization, activity, and stability. Therefore, developing high-performance, long-term stable, and low-cost transition metal catalysts for metal-air batteries is of great significance. Summary of the Invention

[0003] In order to overcome the shortcomings and deficiencies of the existing technology, the primary objective of this invention is to provide a method for preparing porous carbon-supported transition metal composite materials; the method is simple, low-cost, and the resulting composite material has excellent oxygen reduction electrocatalytic activity.

[0004] Another object of the present invention is to provide a porous carbon-supported transition metal composite material prepared by the above preparation method.

[0005] Another object of the present invention is to provide an application of a porous carbon-supported transition metal composite material.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] A method for preparing a porous carbon-supported transition metal composite material, comprising the following steps:

[0008] Transition metal compounds, coordination regulators, and S-C3N4 precursors were added to an organic solvent and mixed. The mixture was stirred for 6 hours and then heated until the organic solvent evaporated. The resulting reactants were then mixed and ground with diphenyldiselenate. The mixture was preheated and then calcined under nitrogen or an inert gas. The calcined product was ground and acid-washed, and then calcined again under nitrogen or an inert gas to obtain a porous carbon-supported transition metal composite material.

[0009] The process of adding the transition metal compound, coordination regulator, and S-C3N4 precursor to an organic solvent for mixing is specifically carried out as follows: the transition metal compound, coordination regulator, and S-C3N4 precursor are added to the organic solvent respectively to obtain a transition metal compound solution, a coordination regulator solution, and an S-C3N4 precursor solution. Then, the transition metal compound solution and the coordination regulator solution are mixed first, and then the S-C3N4 precursor solution is added and mixed.

[0010] The transition metal element in the transition metal compound is one or both of iron and zinc.

[0011] When the transition metal elements in the transition metal compound are iron and zinc, the molar ratio of iron to zinc is (0.1-5):(0.1-3), preferably 1:2;

[0012] The S-C3N4 precursor is synthesized from melamine and / or L-cysteine;

[0013] The coordination regulator is dimethylimidazole, imidazole, triazole, oxygen-containing ligands, and halogen ligands, preferably dimethylimidazole;

[0014] The organic solvent is one or more of ethanol, methanol and acetone, preferably ethanol.

[0015] The heating is carried out in an oil bath at a temperature of 20–100°C, preferably 80°C; the preheating treatment is performed at 200–400°C for 1–2 hours, preferably at 400°C for 1 hour; the calcination temperature is 600–1100°C for 0.5–3 hours, preferably at 900°C for 2 hours.

[0016] The molar ratio of the transition metal compound, coordination regulator, S-C3N4 precursor and diphenyldiselelenide is (0.1-2):(1-10):(0.01-5):(0.01-0.1), preferably (0.1-0.5):(5-6):(0.5-1.5):(0.05-0.08).

[0017] A porous carbon-supported transition metal composite material prepared by the above preparation method, wherein Fe single atoms and FeSe nanoparticles coexist in the composite material.

[0018] The above-mentioned porous carbon-supported transition metal composite materials are used in metal-air batteries.

[0019] A metal-air battery cathode material comprising the aforementioned porous carbon-supported transition metal composite material.

[0020] The present invention has the following advantages and beneficial effects compared with the prior art:

[0021] (1) The present invention provides a method for preparing a porous carbon-supported transition metal composite material. The preparation method uses a pyrolysis synthesis strategy to form porous doped carbon material supported transition metal nanoparticles and single atoms. The present invention develops an electrocatalyst containing Fe single atoms and FeSe nanoparticles on N-doped porous carbon. Due to the synergistic effect between Fe single atoms and FeSe nanoparticles, it has a stronger reactant adsorption capacity and a lower dissociation energy barrier, which is beneficial to breaking OO bonds and accelerating ORR kinetics. It can effectively reduce adsorption energy and synergistically improve catalytic activity, and has excellent catalytic performance.

[0022] (2) The porous carbon-supported transition metal composite material prepared in this invention exhibits excellent oxygen reduction electrocatalytic activity, comparable to that of Pt / C catalysts in alkaline electrolytes, with a half-wave potential reaching 0.89 V (vs. RHE), and demonstrates higher power density and superior 10 mA cm⁻¹ performance compared to commercial Pt / C. -2 Long-term discharge performance and step discharge performance. Attached Figure Description

[0023] Figure 1 XRD patterns of FeSe / Fe-NSC, Fe-NSeC, Fe3C / Fe-NSC and Fe-NC obtained in Examples 1 to 4 of this invention;

[0024] Figure 2 SEM image of FeSe / Fe-NSC prepared in Example 1 of this invention;

[0025] Figure 3 TEM of FeSe / Fe-NSC prepared in Example 1 of this invention;

[0026] Figure 4 The oxygen reduction activity test graphs are shown for FeSe / Fe-NSC, Fe-NSeC, Fe3C / Fe-NSC and Fe-NC prepared in Examples 1 to 4 of the present invention, as well as commercial Pt / C.

[0027] Figure 5 The graph shows the power test results of the magnesium metal air battery provided in Embodiment 7 of the present invention.

[0028] Figure 6 The 10 mA cm of the magnesium metal-air battery provided in Embodiment 7 of the present invention -2 Graph of constant current discharge test results;

[0029] Figure 7 The figure shows the step discharge test results of the magnesium metal air battery provided in Embodiment 7 of the present invention.

[0030] Figure 8The graph shows the power test results of the zinc metal air battery provided in Embodiment 8 of the present invention;

[0031] Figure 9 The 10 mA cm of the zinc metal air battery provided in Embodiment 8 of the present invention -2 Graph of constant current discharge test results;

[0032] Figure 10 The figure shows the step discharge test results of the zinc metal air battery provided in Embodiment 8 of the present invention. Detailed Implementation

[0033] The following specific embodiments further illustrate the content of the present invention, but should not be construed as limiting the present invention.

[0034] Example 1

[0035] This embodiment describes the preparation of a porous carbon-supported transition metal composite material FeSe / Fe-NSC. The specific preparation steps are as follows:

[0036] 4g of melamine and 1g of L-cysteine ​​were mixed and ground, heated to 600℃ at a heating rate of 2℃ / min, and calcined under N2 atmosphere for 2h to obtain nanosheets; 500mg of the obtained nanosheets were dispersed in 250mL of HNO3 under ultrasonic treatment to form solution A; 3.125mL of graphene oxide dispersion was added to solution A and stirred for 6h to obtain a uniform dispersion; the uniform dispersion was filtered, washed three times with deionized water and three times with ethanol, and freeze-dried for 12h to obtain S-C3N4 precursor;

[0037] Solution B: Dissolve 6 mmol of dimethylimidazole (500 mg) in 20 mL of ethanol to obtain solution B;

[0038] Solution C: Dissolve 0.5 mmol of ferric acetylacetone (176.5 mg) in 20 mL of ethanol to obtain solution C;

[0039] Solution D: Dissolve 1 mmol of zinc nitrate (300 mg) in 20 mL of ethanol to obtain solution D;

[0040] Solution E: Dissolve 1g of the S-C3N4 precursor obtained above in 20mL of ethanol to obtain solution E;

[0041] The solutions B, C, and D obtained above were mixed evenly in sequence and stirred for 6 hours. Then, solution E was added and stirred for another 6 hours. The organic solvent was evaporated by drying in an oil bath at 80°C to obtain the S-C3N4-3 precursor.

[0042] 500 mg of S-C3N4-3 precursor and 24 mg of diphenyldiselenic acid were mixed and ground evenly. The mixture was first kept at 400℃ for 1 h, and then calcined at 900℃ for 2 h with a heating rate of 5℃ / min. After grinding and acid washing, the calcined product was activated a second time. The resulting product was denoted as FeSe / Fe-NSC.

[0043] Example 2

[0044] This embodiment describes the preparation of a porous carbon-supported transition metal composite material, Fe-NSeC. The specific preparation steps are as follows:

[0045] 5g of melamine was heated to 600℃ at a heating rate of 2℃ / min and calcined under a N2 atmosphere for 2h to obtain nanosheets; 500mg of the obtained nanosheets were dispersed in 250mL of HNO3 under ultrasonic treatment to form solution A; 3.125mL of graphene oxide dispersion was added to solution A and stirred for 6h to obtain a uniform dispersion; the obtained uniform dispersion was filtered, washed three times with deionized water and three times with ethanol, and freeze-dried for 12h to obtain g-C3N4 precursor;

[0046] Solution B: Dissolve 6 mmol of dimethylimidazole (500 mg) in 20 mL of ethanol to obtain solution B;

[0047] Solution C: Dissolve 0.5 mmol of ferric acetylacetone (176.5 mg) in 20 mL of ethanol to obtain solution C;

[0048] Solution D: Dissolve 1 mmol of zinc nitrate (300 mg) in 20 mL of ethanol to obtain solution D;

[0049] Solution E: Dissolve 1g of the above-obtained g-C3N4 precursor in 20mL of ethanol to obtain solution E;

[0050] The solutions B, C, and D obtained above were mixed evenly in sequence and stirred for 6 hours. Then, solution E was added and stirred for 6 hours. The organic solvent was evaporated by drying in an oil bath at 80°C to obtain the S-C3N4-3 precursor.

[0051] 500 mg of S-C3N4-3 precursor and 24 mg of diphenyldiselenic acid were mixed and ground evenly. The mixture was first kept at 400℃ for 1 h, and then calcined at 900℃ for 2 h with a heating rate of 5℃ / min. The calcined product was ground, acid-washed, and then activated a second time. The resulting product was denoted as Fe-NSeC.

[0052] Example 3

[0053] This embodiment describes the preparation of a porous carbon-supported transition metal composite material, Fe3C / Fe-NSC. The specific preparation steps are as follows:

[0054] 4g of melamine and 1g of L-cysteine ​​were mixed and ground, heated to 600℃ at a heating rate of 2℃ / min, and calcined under N2 atmosphere for 2h to obtain nanosheets; 500mg of the obtained nanosheets were dispersed in 250mL of HNO3 under ultrasonic treatment to form solution A; 3.125mL of graphene oxide dispersion was added to solution A and stirred for 6h to obtain a uniform dispersion; the obtained uniform dispersion was filtered, washed three times with deionized water and three times with ethanol, and freeze-dried for 12h to obtain S-C3N4 precursor;

[0055] Solution B: Dissolve 6 mmol of dimethylimidazole (500 mg) in 20 mL of ethanol to obtain solution B;

[0056] Solution C: Dissolve 0.5 mmol of ferric acetylacetone (176.5 mg) in 20 mL of ethanol to obtain solution C;

[0057] Solution D: 1 mmol of zinc nitrate (300 mg) was dissolved in 20 mL of ethanol to obtain solution D;

[0058] Solution E: 1g of S-C3N4 is dissolved in 20mL of ethanol to obtain solution E.

[0059] The solutions B, C and D obtained above were mixed evenly in sequence and stirred for 6 hours. Then, solution E was added and stirred for 6 hours. The organic solvent was evaporated by drying in an oil bath at 80°C to obtain the S-C3N4-3 precursor.

[0060] 500 mg of the S-C3N4-3 precursor obtained above was first kept at 400℃ for 1 h, and then calcined at 900℃ for 2 h, with a heating rate of 5℃ / min; after grinding and acid washing, the calcined product was activated a second time, and the resulting product was denoted as Fe3C / Fe-NSC.

[0061] Example 4

[0062] This embodiment describes the preparation of a porous carbon-supported transition metal composite material, Fe-NC. The specific preparation steps are as follows:

[0063] 5g of melamine was heated to 600℃ at a heating rate of 2℃ / min and calcined under a N2 atmosphere for 2h to obtain nanosheets; 500mg of the obtained nanosheets were dispersed in 250mL of HNO3 under ultrasonic treatment to form solution A; 3.125mL of graphene oxide dispersion was added to solution A and stirred for 6h to obtain a uniform dispersion; the uniform dispersion was filtered, washed three times with deionized water and three times with ethanol, and freeze-dried for 12h to obtain g-C3N4 precursor;

[0064] Solution B: Dissolve 6 mmol of dimethylimidazole (500 mg) in 20 mL of ethanol to obtain solution B;

[0065] Solution C: Dissolve 0.5 mmol of ferric acetylacetone (176.5 mg) in 20 mL of ethanol to obtain solution C;

[0066] Solution D: Dissolve 1 mmol of zinc nitrate (300 mg) in 20 mL of ethanol to obtain solution D;

[0067] Solution E: Dissolve 1g of the above-obtained g-C3N4 precursor in 20mL of ethanol to obtain solution E;

[0068] The solutions B, C and D obtained above were mixed evenly in sequence and stirred for 6 hours. Then, solution E was added and stirred for 6 hours. The organic solvent was evaporated by drying in an oil bath at 80°C to obtain the S-C3N4-3 precursor.

[0069] 500 mg of the S-C3N4-3 precursor obtained above was first kept at 400℃ for 1 h, and then calcined at 900℃ for 2 h, with a heating rate of 5℃ / min; after grinding and acid washing, the calcined product was activated a second time, and the resulting product was denoted as Fe-NC.

[0070] Example 5

[0071] 1. The FeSe / Fe-NSC, Fe-NSeC, Fe3C / Fe-NSC, and Fe-NC obtained in Examples 1-4 were characterized by XRD, and the results are shown in the figure. Figure 1 .

[0072] like Figure 1 As shown, Examples 1-4 successfully prepared FeSe / Fe-NSC, Fe-NSeC, Fe3C / Fe-NSC, and Fe-NC. The main phase of FeSe / Fe-NSC is FeSe; the main phases of Fe-NSeC and Fe-NC are carbon, while Fe-NC also contains an additional FeN phase; Fe3C / Fe-NSC mainly exhibits the Fe3C phase.

[0073] 2. The FeSe / Fe-NSC prepared in Example 1 was characterized by SEM and TEM. The results are shown in the figure. Figure 2 and Figure 3 .

[0074] like Figure 2 , Figure 3 As shown, the surface of the FeSe / Fe-NSC material is covered with a uniform porous structure. TEM images further reveal clear lattice fringes, with the lattice spacing of the nanoparticles measured to be 0.35 nm, indicating the high quality and good structural order of the material.

[0075] Example 6

[0076] The oxygen reduction activity of FeSe / Fe-NSC, Fe-NSeC, Fe3C / Fe-NSC, and Fe-NC prepared in Examples 1-4, and commercial Pt / C, was tested. The specific preparation steps are as follows:

[0077] Weigh 8 mg of the products obtained in Examples 1-4 into sample vials, add 1 ml of ethanol, 1 ml of deionized water, and 80 μl of Nafion, and sonicate for 30 minutes. After sonication, pipette 12.5 μL of the resulting solution onto a glassy carbon electrode and dry the water and alcohol with an infrared lamp (catalyst loading: 0.4 mg / cm³). 2 Using a glassy carbon electrode as the working electrode, graphite and Ag / AgCl as the counter and reference electrodes, respectively, and 0.1M KOH solution as the electrolyte, linear voltammetry was performed at a rotation speed of 1600 rpm, with a scan range of 0.2–1.0 V (vs. RHE). The test results are shown in [Figure number missing]. Figure 4 .

[0078] like Figure 4 As shown, in the comparison of oxygen reduction activities of catalysts, FeSe / Fe-NSC, Fe-NSeC, Fe3C / Fe-NSC and Fe-NC all exhibited performance comparable to the standard Pt / C catalyst, among which FeSe / Fe-NSC performed the best, with a half-wave potential as high as 0.89V (vs. RHE).

[0079] Example 7

[0080] The metal-air battery was assembled as follows: 8 mg of the product obtained in Example 1 was weighed and placed into a sample vial, and 1 ml of ethanol, 1 ml of deionized water, and 80 μl of Nafion were added. The sample was then sonicated for 30 minutes. A 6.5*2 cm piece of hydrophilic / hydrophobic carbon cloth was cut, and 562.5 μL of the above-prepared solution was evenly added dropwise to a 1.5*1.5 cm area on the hydrophilic side (carbon cloth catalyst loading: 1 mg / cm³). 2 After drying, an air electrode is obtained. It is then assembled into an air battery using a specific mold, with a magnesium sheet as the negative electrode, coated with 1 mg / cm³ of... 2 FeSe / Fe-NSC and Pt / C carbon cloth are used as positive electrodes, and an appropriate amount of 3.5wt% NaCl is added as the electrolyte.

[0081] The magnesium-air batteries assembled according to the above method were used to perform power tests on FeSe / Fe-NSC and Pt / C batteries. The test results are shown below. Figure 5 .

[0082] like Figure 5 As shown, the maximum power density of FeSe / Fe-NSC is 49.2 mW / cm². -2 24.9 mW cm⁻¹ higher than Pt / C-2 This further demonstrates the excellent oxygen reduction performance of FeSe / Fe-NSC.

[0083] The magnesium-air battery assembled according to the above method was used to test FeSe / Fe-NSC and Pt / C at a current density of 10 mA / cm². -2 Constant current discharge test. The test results are shown below. Figure 6 .

[0084] like Figure 6 As shown, the voltage of FeSe / Fe-NSC stabilizes at 1.31V, which is higher than the 1.22V of commercial Pt / C. The specific capacity of FeSe / Fe-NSC is 1198.4 mAh g. -1 Compared to the 1113.7mAh g of commercial Pt / C -1 high.

[0085] The batteries assembled according to the above method were subjected to step discharge tests on FeSe / Fe-NSC and Pt / C. The test results are shown below. Figure 7 .

[0086] like Figure 7 As shown, FeSe / Fe-NSC at open circuit, 2, 5, and 10 mA cm⁻¹ -2 The voltage values ​​below are all higher than Pt / C.

[0087] Example 8

[0088] The metal-air battery was assembled as follows: 8 mg of the product obtained in Example 1 and Pt / C were weighed into a sample vial, and 1 ml of ethanol, 1 ml of deionized water, and 80 μl of Nafion were added. The mixture was then sonicated for 30 minutes. A 6.5*2 cm piece of hydrophilic / hydrophobic carbon cloth was cut, and 562.5 μL of the above-prepared solution was evenly added dropwise to a 1.5*1.5 cm area on the hydrophilic side (carbon cloth catalyst loading: 1 mg / cm³). 2 After drying, an air electrode is obtained. It is then assembled into an air battery using a specific mold, with a zinc sheet as the negative electrode, coated with 1 mg / cm³ of zinc oxide. 2 FeSe / Fe-NSC and Pt / C carbon cloth are used as positive electrodes, and an appropriate amount of 6M KOH is added as the electrolyte.

[0089] The zinc-air batteries assembled according to the above method were used to perform power tests on FeSe / Fe-NSC and Pt / C batteries. The test results are shown below. Figure 8 .

[0090] like Figure 8 As shown, the maximum power density of FeSe / Fe-NSC is 115.4 mW / cm³. -2 58.4 mW cm⁻¹ higher than Pt / C -2This further demonstrates the excellent oxygen reduction performance of FeSe / Fe-NSC.

[0091] The zinc-air battery assembled according to the above method was used to test FeSe / Fe-NSC and Pt / C at a current density of 10 mA / cm². -2 Constant current discharge test. The test results are shown below. Figure 9 .

[0092] like Figure 9 As shown, the voltage of FeSe / Fe-NSC stabilizes at 1.26V, which is higher than the 1.24V of commercial Pt / C. The specific capacity of FeSe / Fe-NSC is 815.4 mAh g. -1 Compared to the 696.5mAh g of commercial Pt / C -1 high.

[0093] The batteries assembled according to the above method were subjected to step discharge tests on FeSe / Fe-NSC and Pt / C. The test results are shown below. Figure 10 .

[0094] like Figure 10 As shown, FeSe / Fe-NSC exhibits performance at open circuit, 2, 5, 10, 15, and 20 mA / cm². -2 The voltage values ​​below are all higher than Pt / C.

[0095] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a porous carbon-supported transition metal composite material, characterized by According to the following operation steps: The transition metal compound, the coordination control agent and the S-C3N4 precursor are respectively added into an organic solvent to obtain a transition metal compound solution, a coordination control agent solution and an S-C3N4 precursor solution, then the transition metal compound solution is mixed with the coordination control agent solution, and then the S-C3N4 precursor solution is added and mixed, stirred for 6 h, then heated, and after the organic solvent is evaporated, the obtained reaction product is mixed and ground with diphenyl diselenide, preheated, calcined at a temperature of 600-1100℃ for 0.5-3 h under nitrogen or inert gas, and the calcined product is ground and pickled, then subjected to secondary calcination under nitrogen or inert gas to obtain a porous carbon loaded transition metal composite material; The transition metal element in the transition metal compound is iron and zinc; the S-C3N4 precursor is synthesized from melamine and L-cysteine; the coordination control agent is one or more of dimethyl imidazole, imidazole, triazole, oxygen-containing ligand and halogen ligand; and the organic solvent is one or more of ethanol, methanol and acetone. The heating is performed under an oil bath, and the heating temperature is 20-100℃; and the preheating treatment is performed at 200-400℃ for 1-2 h.

2. The method for preparing a porous carbon-supported transition metal composite material according to claim 1, characterized in that: The transition metal element in the transition metal compound is iron and zinc, and the molar ratio of iron element to zinc element is (0.1-5)∶(0.1-3); the coordination control agent is dimethyl imidazole; and the organic solvent is ethanol.

3. The method for preparing a porous carbon-supported transition metal composite material according to claim 1, characterized in that: The heating temperature is 80℃; the preheating treatment is performed at 400℃ for 1 h; and the calcination temperature is 900℃ and the time is 2 h.

4. The method for preparing a porous carbon-supported transition metal composite material according to claim 1, characterized in that: The molar ratio of the transition metal compound, the coordination control agent, the S-C3N4 precursor and the diphenyl diselenide is (0.1-2)∶(1-10)∶(0.01-5)∶(0.01-0.1).

5. The method of claim 4, wherein the porous carbon-supported transition metal composite is prepared by the following steps: (a) mixing a transition metal compound with a carbon precursor to form a mixture; (b) heating the mixture to form a carbon-supported transition metal composite; and (c) washing the carbon-supported transition metal composite with water. The molar ratio of the transition metal compound, the coordination control agent, the S-C3N4 precursor and the diphenyl diselenide is (0.1-0.5)∶(5-6)∶(0.5-1.5)∶(0.05-0.08).

6. The porous carbon supported transition metal composite material prepared by the method of any one of claims 1-5, wherein: The Fe single atom and the FeSe nanoparticle coexist in the composite material.

7. Application of the porous carbon loaded transition metal composite material of claim 6 in a metal-air battery.

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