Spongy V2O5 composite Fe intercalation graphite nitrogen N-V2O5 coated FeC and preparation method and application thereof

Abstract

The invention discloses spongy V2O5 composite Fe intercalated graphite nitrogen N-V2O5-coated FeC and a preparation method and application thereof, FeCl3 / KCl and graphite powder are uniformly mixed through ball milling, and Fe intercalated graphite is realized through hot melting at 250 DEG C, so that high-conductivity Fe intercalated graphite FeC is obtained. Then, NH4VO3 and melamine are introduced into the Fe intercalated graphite FeC for secondary ball milling, and the spongy V2O5 composite Fe intercalated graphite nitrogen material is successfully prepared through two-stage heat treatment. The spongy porous structure greatly increases exposure of active sites, and meanwhile, Fe intercalation induced graphite edge defects and Fe-O-V bonds jointly improve the density of the active sites of the V2O5 composite material, so that the activity of the catalyst is enhanced. And secondly, the nitrogen-doped carbon network improves the electron transmission performance and promotes the charge transfer resistance of the catalyst to be reduced to 19.9 ohm. In addition, due to a dual stable mechanism of a Fe-O-V stable structure and V-O-C bond chemical anchoring, the material shows good structural stability under an alkaline condition, and shows excellent electrochemical performance in OER.

Description

Technical Field

[0001] This invention relates to the field of water electrolysis catalyst technology, specifically to a sponge-like V2O5 composite Fe intercalated graphite nitrogen N-V2O5@FeC and its preparation method and application. Background Technology

[0002] With the continuous growth of global energy demand and the increasing prominence of environmental problems, the development of efficient and clean energy conversion materials is urgently needed. Water electrolysis is one of the most promising green energy technologies, using electricity to split water into hydrogen and oxygen. The core reactions in water electrolysis include the oxygen evolution reaction (OER) at the anode and the hydrogen evolution reaction (HER) at the cathode. Thermodynamically, the theoretical equilibrium potential of OER is 1.23 V (vs. HER). However, practical OER often requires higher overpotentials to overcome the reaction energy barrier due to the complex tetraproton coupling electron transfer steps and the formation of multiple oxygen-containing intermediates (OH*, O*, OOH*). Its slow kinetics greatly limit the development of water electrolysis technology. Currently, noble metal OER catalysts (IrO2 and RuO2) are recognized as benchmark materials, but their insufficient stability, high cost, and resource scarcity limit their widespread application. Therefore, developing OER catalysts with high activity and stability is of great significance for energy conversion.

[0003] Vanadium-based materials (such as V₂O₅) are characterized by their rich valence state changes (V₂O₅). 3+ / V 4+ / V 5+ V₂O₅, with its tunable electronic structure, shows great potential in OER (Optical Emission Reduction). However, the poor intrinsic conductivity and insufficient structural stability of V₂O₅ limit its catalytic activity and cycle life. Studies have shown that coupling the active component with a carbon substrate is an effective way to reduce costs and improve catalyst utilization. Typically, the carbon substrate determines the electrochemical active area, particle size distribution, and electron transport of the catalyst. The highly conductive network of the carbon matrix in the composite system can compensate for the insufficient intrinsic conductivity of V-based oxides. Specifically, NC-Co₂V₂O₇, prepared using melamine and glucose as NC (carbon nitride) precursors, exhibits 313.8 mV@10 mA cm⁻¹ in 1 M KOH. -2 (The Tafel slope is 86 mV dec) -1 The V2O5-Fe3O4 / rGO composite material, synthesized via a solvothermal method, exhibits high OER activity and strong stability at 10 mA cm⁻¹. -2 The catalyst exhibits an OER overpotential of 458 mV at a given current density. The VO2 / CFP catalyst, obtained by integrating nanoparticles onto conductive carbon fiber paper (CFP) using vacuum annealing, possesses an OER overpotential of 350 mV and a decimation potential of 46 mV.-1 The Tafel slope. In conclusion, V₂O₅ composite carbon is a potential electrocatalytic material.

[0004] However, V₂O₅ composite carbon materials still have the following drawbacks: 1) Low activity: The carbon material itself lacks effective OER active sites, and the density of active sites on the V₂O₅ surface is insufficient, resulting in poor OER activity of the V₂O₅ composite carbon materials. 2) Poor stability: When V₂O₅ and carbon are composited, the interaction between them is weak, and V₂O₅ is easily peeled off, aggregated, and dissolved from the carbon support. Therefore, there is an urgent need to develop catalyst supports with good stability and highly dispersed active sites. Summary of the Invention

[0005] To address the problems existing in V2O5, the purpose of this invention is to provide a sponge-like V2O5 composite Fe intercalated graphite nitrogen N-V2O5@FeC, its preparation method, and its application.

[0006] To address the problems in the existing technology, the technical solution adopted by this invention is as follows: A method for preparing sponge-like V₂O₅ composite Fe intercalated graphitic nitrogen N-V₂O₅@FeC involves a stepwise synthesis via molten salt-mediated ball milling and pyrolysis, specifically including the following steps: S1: Add graphite powder, FeCl3 and KCl to a ball mill jar, ball mill until uniformly mixed, and transfer to a tube furnace for annealing under an argon atmosphere to obtain FeCl3 intercalated graphite FeC; S2: Add the FeCl3 intercalated graphite FeC, ammonium metavanadate and melamine prepared in step S1 into a ball mill jar, ball mill until uniformly mixed, and transfer to a tube furnace for annealing under an argon atmosphere. S3: The mixture prepared in step S2 was washed several times with hydrochloric acid, deionized water and anhydrous ethanol, and then dried under vacuum to obtain N-V2O5@FeC with a sponge-like structure.

[0007] Preferably, in step S1, the mass of graphite powder is 0.3 g; the mass of FeCl3 is 6 g; and the mass of KCl is 2 g.

[0008] Preferably, in step S1, the ball milling speed is 250 rpm to 350 rpm, and the processing time is 20 min to 40 min.

[0009] Preferably, in step S1, the annealing treatment is carried out in argon gas at 250 ºC ± 20 ºC for 2 h, with a heating rate of 4 ℃ / min. -1 .

[0010] Preferably, in step S2, the masses of ammonium metavanadate and melamine are 0.3 g and 4 g, respectively. It is necessary to control the amount of melamine added during this process; adding too little or too much melamine will result in poor electrochemical performance and structural stability of the composite.

[0011] Preferably, in step S2, the ball milling speed is 250 rpm to 350 rpm, and the processing time is 20 min to 40 min.

[0012] Preferably, in step S2, the mixture is heated at 250 ± 20 °C for 2 h in argon atmosphere to allow FeCl3-KCl to co-melt, and then heated to 500 ± 50 °C for 3 h, with a heating rate of 4 °C / min. -1 .

[0013] Preferably, in step S3, the concentration of hydrochloric acid used is 1 mol / L. -1 .

[0014] Preferably, in step S3, the vacuum drying temperature is 60 °C and the time is 6 h to 8 h.

[0015] The sponge-like V₂O₅ composite Fe-intercalated graphitic nitrogen N-V₂O₅@FeC prepared by any of the above preparation methods has an Fe-intercalated graphite structure, is a sponge-like porous structure, and contains OVO, VO, V=O and VO-Fe groups, V₆O 13 The interplanar spacing is 0.26 nm, and the material also contains lattice defects and amorphous carbon nitride. Its electrochemical specific surface area is 2.94 cm². -2 .

[0016] The above-mentioned spongy V2O5 composite Fe intercalated graphite nitrogen N-V2O5@FeC is used as a catalyst in the electrolysis of water to produce oxygen.

[0017] Preferably, the N-V₂O₅@FeC catalyst exhibits good activity in 1.0 M KOH. η 10 =299 mV, Tafel slope is 53.0 mV dec -1 It has excellent conductivity, a charge transfer resistance of 19.8 Ω, and a stability of 50 h. Beneficial effects

[0018] Compared with existing technologies, this invention provides a sponge-like V₂O₅ composite Fe-intercalated graphite nitrogen material (N-V₂O₅@FeC), its preparation method, and its application. The method involves ball milling to achieve uniform mixing of FeCl₃ / KCl and graphite powder, followed by hot melting at 250 °C to achieve Fe intercalation into graphite, resulting in highly conductive Fe intercalated graphite FeC. Subsequently, NH₄VO₃ and melamine are introduced into the Fe intercalated graphite FeC for secondary ball milling, followed by a two-stage heat treatment to successfully prepare the sponge-like V₂O₅ composite Fe intercalated graphite nitrogen material (N-V₂O₅@FeC) as an OER catalyst. This invention offers the following advantages: (1) The molten salt method, which is used as a liquid-phase synthesis route in this invention, shows significant advantages in the preparation of FeCl3 / KCl intercalated graphite. The addition of KCl lowers the eutectic temperature to 250 °C and promotes the uniform dispersion of FeCl3 between graphite layers. The chemical stability and high fluidity of the molten salt medium provide an ideal mass transfer environment for the intercalation reaction. The resulting Fe intercalated graphite induces electron delocalization to form a built-in electric field, i.e., a unique interlayer electronic structure. In addition, the N doping introduced by melamine improves the conductivity of the material.

[0019] (2) In this invention, the release of NH3 during the pyrolysis of melamine forms bubbles inside the material, promoting the formation of a sponge-like porous structure. This sponge-like porous structure significantly increases the exposure of active sites. Simultaneously, the graphite edge defects induced by Fe intercalation and the Fe-OV bonds jointly enhance the active site density of the V2O5 composite material, thereby strengthening the catalyst activity. Furthermore, the lattice stabilizing effect of the Fe-OV bonds and the strong coordination anchoring effect of the VOC bonds jointly inhibit the dissolution and aggregation of V2O5, thus enhancing stability.

[0020] (3) The sponge-like V2O5 composite Fe intercalated graphite nitrogen N-V2O5@FeC of this invention is used as an OER catalyst. The advantages of N-V2O5@FeC are: 1) High catalytic activity: Fe intercalation-induced graphite edge defect sites provide additional active sites. Secondly, Fe... 3+ The Fe-OV formation with the V2O5 lattice not only introduces new active centers but also inhibits V2O5 aggregation, thus enhancing the catalytic activity of the material. Furthermore, the large active surface area of ​​the sponge-like porous structure provides more active sites for OER, improving the contact efficiency between the catalyst and reactants and further enhancing catalytic activity. 2) Good electrical conductivity: Fe intercalation into graphite induces electron delocalization, forming a built-in electric field that reduces charge transfer resistance. Simultaneously, the NH3 released during the thermal decomposition of melamine partially displaces the Fe... 3+ Reduced to Fe 2+ The Fe formed 3+ / Fe 2+Redox pairs couple electronically with V₂O₅, improving conductivity. Furthermore, the N doping introduced by melamine also enhances the material's conductivity. 3) Strong stability: The introduction of Fe forms a stable lattice structure through Fe-OV chemical bonds, effectively mitigating V₂O₅ aggregation and dissolution. Simultaneously, the nitrided graphite coating provides more stable carbon layer protection by anchoring the active center through VOC bonds, thereby improving the stability of V₂O₅ under alkaline conditions. Based on these advantages, N-V₂O₅@FeC exhibits excellent electrochemical performance in the oxygen evolution reaction. Attached Figure Description

[0021] Figure 1 This is a scanning electron microscope (SEM) image of N-V2O5@FeC synthesized in Example 1.

[0022] Figure 2 This is a transmission electron microscope (TEM) image of N-V2O5@FeC synthesized in Example 1.

[0023] Figure 3 This is a high-magnification transmission electron microscope (HRTEM) image of N-V2O5@FeC synthesized in Example 1.

[0024] Figure 4 Mapping diagram of N-V2O5@FeC synthesized in Example 1.

[0025] Figure 5 The energy dispersive spectrum (EDS) of N-V2O5@FeC synthesized in Example 1 is shown.

[0026] Figure 6 This is a scanning electron microscope image of V2O5 synthesized in Comparative Example 1.

[0027] Figure 7 The image shown is a scanning electron microscope image of V2O5@C synthesized in Comparative Example 2.

[0028] Figure 8 The image shows a scanning electron microscope (SEM) image of V2O5@FeC synthesized in Comparative Example 3.

[0029] Figure 9 The Fourier transform infrared (FT-IR) spectra of Examples 1 and Comparative Examples 1-3 are shown.

[0030] Figure 10 The images show the Raman spectra of Examples 1 and Comparative Examples 1-3.

[0031] Figure 11 The X-ray diffraction (XRD) patterns are for Example 1 and Comparative Examples 1-3.

[0032] Figure 12 Electron paramagnetic (EPR) diagrams for Example 1 and Comparative Examples 1-3.

[0033] Figure 13 This is the X-ray photoelectron spectroscopy (XPS) spectrum of Example 1.

[0034] Figure 14 The oxygen evolution reaction polarization curves (LSV) of the catalysts prepared in Example 1 and Comparative Examples 1-3 are shown.

[0035] Figure 15 The image shows the Tafel slope diagrams of the oxygen evolution reaction of the catalysts prepared in Example 1 and Comparative Examples 1-3.

[0036] Figure 16 The above are the electrochemical impedance spectroscopy (EIS) spectra of the oxygen evolution reaction of the catalysts prepared in Example 1 and Comparative Examples 1-3.

[0037] Figure 17 The image shows the electrochemical active surface area (ECSA) of the catalysts prepared in Example 1 and Comparative Examples 1-3.

[0038] Figure 18 This is a stability test diagram of the catalyst prepared in Example 1. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in detail below with reference to the embodiments.

[0040] This invention discloses a method for preparing sponge-like V₂O₅ composite Fe intercalated graphite nitrogen N-V₂O₅@FeC, the specific steps of which are as follows: 1) Add 0.3 g graphite powder, 6 g FeCl3 and 2 g KCl to a ball mill jar and ball mill for 20 min to 40 min (250 rpm to 350 rpm) until uniformly mixed. Then, heat the mixture in a tube furnace under an argon atmosphere at a heating rate of 4 °C / min. -1 Heating to 250 ℃±20 ºC for 2 h yielded FeCl3 intercalated graphite FeC; 2) Add (2 mmol) NH4VO3 and (4 g) melamine to the mixture and ball mill for 30 min to ensure uniform mixing. Transfer the mixture to a tube furnace and heat at a rate of 4 °C min under an argon atmosphere. -1 The temperature was increased to 250 ℃±20 ºC and held for 2 h to allow FeCl3-KCl to co-melt, and then the temperature was increased to 500 ℃±50 ºC and held for 3 h. 3) The product was washed twice with 1 M HCl to remove free Fe, and then washed with deionized water and anhydrous ethanol respectively. It was then vacuum dried at 60 °C for 6 h to obtain sponge-like N-V2O5@FeC.

[0041] Example 1

[0042] 1) Weigh 0.3 g of graphite powder, 6 g of FeCl3, and 2 g of KCl into a ball mill jar, and ball mill at 300 rpm for 30 min to mix evenly. Transfer the mixture to a tube furnace and mill at 4 °C for 1 min under an argon atmosphere. -1 The temperature was increased to 250 °C and held for 2 h to obtain FeCl3 intercalated graphite FeC; 2) Weigh 0.234 g (2 mmol) NH4VO3 and 4 g melamine and add them to FeC. Ball mill at 300 rpm for 30 min to mix them evenly. Transfer the mixture to a tube furnace and keep it at 250 ℃ for 2 h under an argon atmosphere. Then raise the temperature to 500 ℃ and keep it for 3 h. 3) The product was washed twice with 1 M HCl to remove free Fe, and then washed with deionized water and anhydrous ethanol respectively. It was then vacuum dried at 60 °C for 6 h to obtain sponge-like N-V2O5@FeC.

[0043] Figure 1 SEM image of N-V2O5@FeC synthesized in this embodiment. A sponge-like porous structure with uniform pores can be observed.

[0044] Figure 2 This is a TEM image of the synthesized N-V2O5@FeC in this embodiment. It can be observed that the NH3 gas generated by the pyrolysis of melamine forms a sponge-like porous structure on the soft template, increasing the specific surface area of ​​the material.

[0045] Figure 3 This is an HRTEM image of the N-V₂O₅@FeC catalyst synthesized in this example. V₆O₅ can be observed. 13 The interplanar spacing is 0.26 nm. Additionally, the material contains lattice defects (marked by yellow dashed circles) and amorphous carbon nitride (marked by red dashed circles).

[0046] Figure 4 The mapping diagram of N-V2O5@FeC synthesized in this embodiment is shown. As can be seen from the figure, C, N, O, V and Fe elements are distributed on the material surface, indicating that C, N, O and V elements are uniformly distributed in N-V2O5@FeC, while Fe has a sparse distribution in the C-rich region, indicating that Fe preferentially inserts into graphite edge defects in the molten salt.

[0047] Figure 5 The image shows the EDS spectrum of the N-V2O5@FeC synthesized in this embodiment. As can be seen from the image, it contains Cu, C, N, O, V, and Fe elements, with the Cu element derived from the copper mesh. Therefore, the material contains C, N, O, V, and Ni elements, with mass contents of 28.48%, 3.90%, 23.57%, 35.77%, and 8.26%, respectively.

[0048] Figure 9 The infrared spectrum of N-V2O5@FeC synthesized in this embodiment is shown. As can be seen from the figure, the prepared N-V2O5@FeC has abundant functional groups (C=C, OVO and Fe-OV).

[0049] Figure 10 The image shows the Raman spectroscopy diagram of the synthesized N-V₂O₅@FeC in this embodiment. As can be seen from the diagram, the prepared N-V₂O₅@FeC contains OVO, VO, V=O, and VO-Fe groups.

[0050] Figure 11 XRD pattern of N-V₂O₅@FeC synthesized for this embodiment. (From...) Figure 11 Characteristic peaks at 25.3 °, 26.9 °, 30.1 °, 33.5 °, 37.0 °, 42.1 °, 45.6 °, 49.5 °, 55.6 °, 62.5 °, and 64.0 ° are observed, corresponding to V6O, respectively. 13 (PDF#89-0612) phases (110), (003), (-401), (310), (311), (204), (005), (-603), (006), (-713), and (-207). NH4VO3 and NH3 produced by the thermal decomposition of melamine partially reduce V. 5 .

[0051] Figure 12 The figure shows the EPR spectrum of N-V₂O₅@FeC synthesized in this embodiment. The strong EPR signal response with a g value of 1.9826 indicates that V in the material... 4+ The ion concentration is high. The electron delocalization effect induced by nitrogen atoms alters the spin density distribution, while the dynamic Jahn-Teller effect and Fe-V spin coupling together lead to a significant broadening of the spectral lines.

[0052] Figure 13 XPS elemental electron spectra of the N-V₂O₅@FeC catalyst prepared in this embodiment. As can be seen from the figure, the prepared material is mainly composed of C, N, O, V and Fe elements.

[0053] Comparative Example 1: Weigh 0.234 g (2 mmol) of NH4VO3 and transfer it to a tube furnace. Heat at a rate of 4 °C min under an argon atmosphere. -1 The temperature was raised to 250 °C and held for 2 h, then raised to 500 °C and held for 3 h to obtain V2O5.

[0054] Figure 6 The SEM image of this embodiment shows that V2O5 exhibits a stacked, sheet-like structure that is relatively aggregated.

[0055] Comparative Example 2: Weigh 0.3 g of graphite powder and 0.234 g (2 mmol) of NH4VO3 and add them to a ball mill jar. Ball mill at 300 rpm for 30 min to mix them evenly. Transfer the mixture to a tube furnace and heat at 4 °C / min under an argon atmosphere. -1 The temperature was raised to 250 °C and heated for 2 hours, then raised to 500 °C and heated for 3 hours to obtain V2O5@C.

[0056] Figure 7 In the SEM image of this embodiment, V2O5@C is a uniformly loaded sheet structure, but its interlayer spacing is still relatively small.

[0057] Comparative Example 3: 1) Weigh 0.3 g of graphite powder, 6 g of FeCl3, and 2 g of KCl into a ball mill jar, and ball mill at 300 rpm for 30 min to mix evenly. Transfer the mixture to a tube furnace and mill at 4 °C for 1 min under an argon atmosphere. -1 The temperature was increased to 250 °C and held for 2 h to obtain FeCl3 intercalated graphite FeC; 2) Weigh 0.234 g (2 mmol) NH4VO3 and 4 g melamine and add them to FeC. Ball mill at 300 rpm for 30 min to mix evenly. Transfer to a tube furnace and keep at 250 ℃ for 2 h under argon atmosphere. Then raise the temperature to 500 ℃ and keep for 3 h to obtain V2O5@FeC.

[0058] Figure 8 In the SEM image of this embodiment, the V2O5@FeC surface is smooth and flat, and no stacking phenomenon was observed.

[0059] Example 2: Parallel experiments were conducted using the electrode material prepared in Example 1: Electrolysis of water: Electrochemical performance tests were performed in a typical three-electrode system at room temperature (approximately 25°C). A glassy carbon electrode (GCE, diameter: 3 mm, area: 0.07 cm²) was used. 2 The electrochemical performance of the oxygen evolution reaction was tested using a graphite rod as the working electrode, a graphite rod as the counter electrode, and Hg / HgO as the reference electrode. All reported potentials were converted to the reversible hydrogen electrode (RHE) potential using the following formula: E (RHE) = E (Hg / HgO) +0.0591*pH +0.098 V. All electrochemical tests were performed on a CHI660E electrochemical workstation (Shanghai).

[0060] The glassy carbon electrode was coated with a catalyst. Specifically, 5 mg of catalyst and 0.625 mg of Supercarbon were uniformly dispersed in a mixed solution of 950 μL anhydrous ethanol and 50 μL Nafion solution (5 wt%). Then, 5 μL of catalyst was dropped onto the surface of the glassy carbon electrode to serve as the working electrode. Before conducting the electrochemical experiment, the electrolyte was purified with pure nitrogen for 30 minutes, and then the coated working electrode was immersed in the electrolyte for operation.

[0061] Figure 14 The graph shows the LSV curves of the oxygen evolution reaction of the catalysts prepared in Example 1 and Comparative Examples 1-3. As can be seen from the graph, with V₂O₅ (411 mV @ 10 mA cm⁻¹), the reaction proceeds as follows: -2 ), V2O5@C (366 mV@10 mA cm -2 ), V2O5@FeC (334 mV@10 mA cm -2 In comparison, the N-V2O5@FeC prepared in Example 1 only requires 299 mV to reach 10 mA cm⁻¹. -2 Current density.

[0062] Figure 15 This is a Tafel slope diagram of the catalysts prepared in Example 1 and Comparative Examples 1-3. As can be seen from the diagram: with V₂O₅ (150.3 mV dec... -1 ), V2O5@C (119.1 mV dec) -1 ) and V2O5@FeC (93.5 mV dec -1 Compared to the N-V2O5@FeC (53.0 mV dec) prepared in Example 1, -1 The small Tafel slope indicates that its catalyst has high OER activity.

[0063] Figure 16 The EIS diagrams of the catalysts prepared in Example 1 and Comparative Examples 1-3 are shown. As can be seen from the diagrams, compared with V2O5 (130.6 Ω), V2O5@C (76.5 Ω), and V2O5@FeC (56.8 Ω), N-V2O5@FeC (19.9 Ω) has a lower charge transfer resistance, indicating that the N-V2O5@FeC catalyst has high conductivity.

[0064] Figure 17 The image shows the ECSA diagrams of the catalysts prepared in Example 1 and Comparative Examples 1-3. As can be seen from the diagrams: [The text abruptly shifts to a different topic] ...with V₂O₅ (1.77 cm⁻¹) -2 ), V2O5@C (2.22 cm) -2 ) and V2O5@FeC (2.54 cm -2 Compared to N-V2O5@FeC (2.94 cm),-2 The large electrochemically active specific surface area indicates that N-V2O5@FeC has better catalytic activity.

[0065] Figure 18 The chronoamperometry (It) of N-V₂O₅@FeC prepared in Example 1 is shown in the figure. As can be seen from the figure, N-V₂O₅@FeC exhibits chronoamperometry at 10 mA cm⁻¹. -2 The fluctuations in current density indicate good long-term stability.

[0066] In summary, this invention successfully prepared a sponge-like V₂O₅ composite material N-V₂O₅@FeC using a molten salt-mediated ball milling-pyrolysis method, which exhibited excellent electrochemical performance in OER (Organic Emission Reduction). This invention optimizes the electronic structure of the active center by forming Fe-OV bonds through molten Fe intercalation in graphite. Simultaneously, the NH₃ released during the thermal decomposition of melamine serves as a soft template to form a sponge-like porous structure, providing more active sites for OER and thus improving catalytic activity. The electron delocalization effect of Fe intercalation in graphite, together with the nitrogen-doped carbon network, enhances the material's conductivity. The lattice stabilizing effect of Fe-OV bonds and the strong coordination anchoring effect of VOC bonds jointly inhibit the dissolution and aggregation of V₂O₅, thereby enhancing stability. Based on these advantages, the N-V₂O₅@FeC catalyst exhibits good activity in 1.0 M KOH (…). η 10 =299 mV, Tafel slope is 53.0 mV dec -1 ), conductivity (19.8 Ω) and stability (50 h).

Claims

1. A method for preparing a sponge-like V2O5 composite Fe intercalated graphite nitrogen N-V2O5@FeC, characterized in that, Synthesized by a method of molten salt mediated ball milling and pyrolysis step-by-step treatment, specifically comprising the following steps: S1: adding graphite powder, FeCl3 and KCl into a ball milling tank, ball milling until mixed uniformly, and transferring into a tube furnace to perform annealing treatment under argon atmosphere to obtain FeCl3 intercalated graphite FeC; S2: adding the FeCl3 intercalated graphite FeC prepared in step S1, ammonium metavanadate and melamine into a ball milling tank, ball milling until mixed uniformly, and transferring into a tube furnace to perform annealing treatment under argon atmosphere; S3: sequentially washing the mixture prepared in step S2 with hydrochloric acid, deionized water and anhydrous ethanol for several times, and vacuum drying to obtain N-V2O5@FeC with a sponge-like structure.

2. The production method according to claim 1, characterized by, In step S1, the mass of graphite powder is 0.3 g; the mass of FeCl3 is 6 g; and the mass of KCl is 2 g.

3. The production method according to claim 1, characterized by, In step S1, the rotation speed of the ball milling treatment is 250 rpm to 350 rpm, and the treatment time is 20 min to 40 min; the annealing treatment is performed in argon at 250 °C ± 20 °C for 2 h, and the heating rate is 4 °C min -1 .

4. The production method according to claim 1, characterized by, In step S2, the mass of ammonium metavanadate and melamine is 0.3 g and 4 g respectively.

5. The production method according to claim 1, characterized by, In step S2, the rotation speed of the ball milling treatment is 250 rpm to 350 rpm, and the treatment time is 20 min to 40 min; heating at 250 ± 20℃ for 2 h in argon, co-melting of FeCl3-KCl, and then heating at 500 ± 50℃ for 3 h, with a heating rate of 4℃ / min -1 .

6. The production method according to claim 1, characterized by, In step S3, the concentration of the hydrochloric acid used is 1 mol L -1 .

7. The production method according to claim 1, characterized by, In step S3, the temperature during vacuum drying is 60 ℃, and the time is 6 h-8 h.

8. The sponge-like V2O5 composite Fe intercalated graphite nitrogen N-V2O5@FeC prepared based on the preparation method of any one of claims 1-7, characterized in that, The sponge-like V2O5 composite Fe intercalated graphite nitrogen N-V2O5@FeC has a Fe intercalated graphite structure, is a sponge-like porous structure, has O-V-O, V-O, V=O and V-O-Fe groups, V6O 13 The interplanar spacing of the crystal face is 0.26 nm, and there are also crystal lattice defects and amorphous carbon nitride in the material, and the electrochemical specific surface area is 2.94 cm -2 .

9. Use of the sponge-like V2O5 composite Fe intercalated graphite nitrogen N-V2O5@FeC as a catalyst for electrolysis of water to produce oxygen according to claim 8.

10. Use according to claim 9, characterized in that, The N-V2O5@FeC catalyst exhibits good activity in 1.0 M KOH, η 10 = 299 mV, and the Tafel slope is 53.0 mV dec -1 , has good conductivity, the charge transfer resistance is 19.8 Ω, and the stability reaches 50 h.

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