Preparation method of efficient membrane electrode based on monatomic catalyst
By loading NiFeMo single-atom catalysts on the surface of nickel foam and fixing Pt single atoms on the surface of nickel felt, and assembling membrane electrodes using a hot pressing process, the problems of low efficiency of anode OER and cathode HER in hydrogen production by water electrolysis were solved, and efficient and stable green hydrogen production was achieved.
Patent Information
- Application Number
- CN202511230618.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-30
- Publication Date
- 2025-10-17
AI Technical Summary
In the existing technology, the anode OER reaction kinetics of water electrolysis to produce hydrogen is slow, resulting in high overpotential and increased energy consumption. The precious metals of the cathode HER catalyst are scarce and the non-precious metals are insufficiently active. The existing single-atom catalyst synthesis method is complex and costly.
The NiFeMo single-atom catalyst was loaded on the surface of nickel foam by wet chemical impregnation and a nitrogen-doped carbon coating was formed. The carbon coating was deposited by acetylene pyrolysis and electrochemical deposition was combined to fix Pt single atoms on the surface of nickel felt. The membrane electrode was assembled by hot pressing.
It significantly improves the catalytic activity and stability of the membrane electrode, reduces the cost of hydrogen production, and is suitable for industrial-grade green hydrogen production. It can operate stably for 1,000 hours at industrial-grade current density, with a production cost as low as US$1.5/kg.
Abstract
Description
TECHNICAL FIELD
[0001] The present application belongs to the technical field of catalysts. More particularly, it relates to a preparation method of a high-efficiency membrane electrode based on a single-atom catalyst. BACKGROUND
[0002] Hydrogen is a clean and renewable energy carrier. Among the existing hydrogen production methods, water electrolysis is a convenient, efficient and promising method for producing hydrogen, which has the advantages of being clean, sustainable and high in hydrogen purity. The water electrolysis reaction occurs on the surface of the membrane electrode catalyst layer, including the cathode hydrogen evolution reaction (HER) and the anode oxygen evolution reaction (OER).
[0003] For the anode, due to the slow kinetics of the OER reaction, the overpotential is high, and a higher external voltage than the theoretical decomposition voltage is required to drive the reaction, resulting in increased energy consumption. Therefore, for the anode, it is crucial to develop stable and efficient electrocatalytic materials, the core of which is to improve the catalytic activity to reduce the reaction onset potential, reduce the Tafel slope to accelerate the reaction kinetics, and improve the long-range stability and cycle stability of the electrode material to break through the bottleneck of high energy consumption and insufficient service life.
[0004] For the cathode, important progress has been made in the study of HER catalysts, but there are still many key challenges: the scarcity and high cost of noble metal Pt severely restrict its large-scale application, and in alkaline conditions, the intrinsic activity of non-noble metal alternative materials (such as transition metal sulfides, phosphides, etc.) is still generally insufficient, and the slow water dissociation kinetics leads to a high reaction overpotential. Therefore, for the cathode, it is imperative to develop ultra-low Pt cathode catalysts with high activity and stability.
[0005] In recent years, single-atom catalysts have attracted widespread attention in the fields of catalysis and energy. Compared with traditional nano-catalysts (metal nanoparticles, clusters, etc.), single-atom catalysts have a theoretical atom utilization rate of 100% and excellent catalytic activity, which can effectively reduce the cost of catalysts; at the same time, single-atom catalysts have good stability and can be effectively recycled multiple times. The current preparation methods of single-atom catalysts are mainly based on impregnation, photoreduction, atomic layer deposition, etc. So far, researchers have designed and developed many electrocatalysts, but there are still problems such as complex synthesis method, poor catalytic activity and high preparation cost.
[0006] In summary, how to design and prepare a single-atom catalyst with a simple preparation method, high catalytic activity, good stability and low cost is a problem that needs to be solved urgently. SUMMARY
[0007] The technical problem solved by the present application is to overcome the defects and deficiencies of the prior art and provide a preparation method of a high-efficiency membrane electrode based on a single-atom catalyst.
[0008] The purpose of the present application is to provide a preparation method of a high-efficiency membrane electrode based on a single-atom catalyst.
[0009] The above-mentioned purpose of the present application is achieved by the following technical solutions. The present application provides a high-efficiency membrane electrode based on a single-atom catalyst, comprising: An anode, a NiFeMo single-atom catalyst is loaded on the surface of a foamed nickel by a wet chemical immersion method, and then a nitrogen-doped carbon coating layer is loaded by gas-phase deposition; A cathode, a carbon coating layer is deposited on the surface of a nickel felt by acetylene pyrolysis, and Pt single atoms are fixed by an electrochemical deposition method.
[0010] Preferably, the thickness of the foamed nickel is 0.3-0.5 mm, and the porosity is 80-95%.
[0011] Further preferably, the thickness of the nitrogen-doped carbon coating layer is 1-2 nm, and the loading amount of the NiFeMo single-atom catalyst is 0.1-0.3 mg / cm 2 .
[0012] Preferably, the thickness of the nickel felt is 0.2-0.4 mm, the acetylene pyrolysis carbon coating layer is deposited at 700-900℃, and the Pt single atoms are fixed by the electrochemical deposition method at a potential of 0.5-1.0 V (vs. RHE).
[0013] Further preferably, the thickness of the acetylene pyrolysis carbon coating layer is 5-7 μm, and the loading amount of the Pt single atoms is 0.02-0.1 mg / cm 2 .
[0014] The above-mentioned preparation method of a high-efficiency membrane electrode based on a single-atom catalyst comprises the following steps: (1) Anode preparation, foamed nickel is immersed in a mixed solution containing Ni, Fe and Mo precursors, ultrasonic dispersion is performed, vacuum immersion is performed, foamed nickel loaded with NiFeMo is obtained, then a carbon source and a nitrogen source are mixed, annealing is performed in an N2 (nitrogen) atmosphere, N2 is used for purging, and a nitrogen-doped carbon coating layer is formed on the foamed nickel loaded with NiFeMo; (2) Cathode preparation, a carbon coating layer with a thickness of 5-7 μm is deposited on the surface of a nickel felt by acetylene pyrolysis; Pt single atoms are electrochemically deposited at a potential of 0.5-1.0 V (vs. RHE); the Pt single atoms are uniformly fixed on the surface of the carbon coating layer by the electrochemical deposition method; and the acetylene pyrolysis carbon coating layer provides high specific surface area and corrosion resistance.
[0015] (3) membrane electrode assembly, the anode, AEM membrane and cathode are stacked, and a composite membrane electrode with an interface resistance of ≤3 mΩ·cm is prepared by a hot pressing process. 2
[0016] Preferably, in step (1), Ni(NO3)2, Fe(NO3)3 and MoO3 are dissolved in pure water and uniformly mixed, then the foam nickel is added and ultrasonic dispersion is carried out, vacuum impregnation is carried out at 60-80 DEG C, and then washing is carried out to obtain the foam nickel loaded with NiFeMo, ethylene glycol is used as a carbon source, urea is used as a nitrogen source, urea and ethylene glycol are mixed, and then annealing is carried out at 400-600 DEG C in a N2 atmosphere, N2 is used for purging, and a nitrogen-doped carbon coating layer is formed on the foam nickel loaded with NiFeMo. The molar ratio of Ni, Fe and Mo is 3:1:0.5, and the mass-volume ratio of urea to ethylene glycol is 1 g:8 mL. The loading amount of the NiFeMo single-atom catalyst is 0.1-0.3 mg / cm 2 , and the overpotential is ≤310 mV 2 @10 mA / cm 2 .
[0017] Preferably, in step (2), the acetylene pyrolytic carbon coating layer is deposited at 700-900 DEG C, and the loading amount of the Pt single atom is 0.02-0.1 mg / cm 2 , and the hydrogen evolution overpotential is ≤30 mV 2 @10 mA / cm.
[0018] Preferably, in step (3), the anode, the AEM membrane and the cathode are stacked in sequence, and the composite membrane electrode is prepared by hot pressing at 0.5-1.5 MPa and 60-100 DEG C for 3-10 minutes, and the thickness of the AEM membrane is 90 μm.
[0019] The application of the above-mentioned high-efficiency membrane electrode based on a single-atom catalyst, and the composite membrane electrode is used in an anion exchange membrane water electrolyzer or a proton exchange membrane water electrolyzer.
[0020] Under the condition of 1 M KOH and 80 DEG C, a cell voltage of 1.78 V@2 A / cm 2 is achieved, the energy efficiency is ≥75%, and the stable operation time is ≥1000 hours@3 A / cm 2 .
[0021] The application has the following beneficial effects: 1. The application loads the NiFeMo single-atom catalyst on the surface of the foam nickel by a wet chemical impregnation method, the carrier is a nitrogen-doped carbon coating layer to prepare an anode, a carbon coating layer is deposited on the surface of the nickel felt by acetylene pyrolysis, and Pt single atoms are fixed by an electrochemical deposition method to prepare a cathode, and then a hot pressing process is used for assembly to form a composite membrane electrode with an interface resistance of ≤3 mΩ·cm 2The membrane electrode can be stably operated for 1000 hours under an industrial current density (3 A / cm 2 ) and the production cost of hydrogen is as low as 1.5 dollars / kg, which is suitable for large-scale green hydrogen production.
[0022] 2. The application significantly improves the catalytic activity, stability and interface conductivity of the membrane electrode by combining the in-situ loading of single-atom catalysts with the membrane electrode hot pressing process, which is suitable for industrial green hydrogen production and has a wide market application prospect. The preparation method is simple, easy to operate and implement.
[0023] 3. The prepared catalyst can be applied to water electrolysis to produce hydrogen, and the catalyst has high catalytic activity and stability, which can effectively reduce the production cost of hydrogen production. DETAILED DESCRIPTION
[0024] The application will be described in detail below with examples. Each example is provided by way of explanation of the application rather than limitation of the application. In fact, those skilled in the art will clearly understand that modifications and variations can be made in the application without departing from the scope or spirit of the application. For example, features shown or described as part of one embodiment can be used in another embodiment to produce yet another embodiment. All other embodiments obtained by those skilled in the art based on the embodiments in the application should belong to the scope of protection of the embodiments in the application.
[0025] A high-efficiency membrane electrode based on single-atom catalysts, comprising: An anode, a NiFeMo single-atom catalyst is loaded on the surface of a nickel foam by a wet chemical immersion method, and then a nitrogen-doped carbon coating layer is loaded by vapor deposition; the thickness of the nickel foam is 0.3-0.5 mm, and the porosity is 80-95%; the thickness of the nitrogen-doped carbon coating layer is 1-2 nm, and the loading amount of the NiFeMo single-atom catalyst is 0.1-0.3 mg / cm 2 .
[0026] A cathode, a carbon coating layer is deposited on the surface of a nickel felt by acetylene pyrolysis, and Pt single atoms are fixed by electrochemical deposition; the thickness of the nickel felt is 0.2-0.4 mm, the acetylene pyrolysis carbon coating layer is deposited at 700-900℃, the thickness of the acetylene pyrolysis carbon coating layer is 5-7 μm, the Pt single atoms are fixed by electrochemical deposition at a potential of 0.5-1.0 V (vs. RHE), and the loading amount of the Pt single atoms is 0.02-0.1 mg / cm 2 .
[0027] A preparation method of a high-efficiency membrane electrode based on single-atom catalysts, comprising the following steps: (1) Anode preparation, dissolve Ni(NO3)2, Fe(NO3)3 and MoO3 in pure water and mix uniformly, add foamed nickel and ultrasonic dispersion, vacuum impregnation at 60-80℃, rinse, get NiFeMo loaded foamed nickel, use ethylene glycol as carbon source, urea as nitrogen source, mix urea and ethylene glycol, then anneal at 400-600℃ in N2 atmosphere, use N2 purge, form nitrogen-doped carbon coating layer on the NiFeMo loaded foamed nickel, the molar ratio of Ni, Fe and Mo is 3:1:0.5, the mass-volume ratio of urea to ethylene glycol is 1 g:8 mL. The NiFeMo single-atom catalyst is stably dispersed through the nitrogen-doped carbon coating layer, and the loading of the NiFeMo single-atom catalyst is 0.1-0.3 mg / cm 2 , overpotential ≤310 mV 2 A / cm 2 ; The nitrogen-doped carbon layer enhances electron conductivity and reduces interface resistance.
[0028] (2) Cathode preparation, deposit a 5-7 μm thick carbon coating layer on the surface of the nickel felt through acetylene pyrolysis, and the acetylene pyrolysis carbon coating layer is deposited at 700-900℃; Electrochemically deposit Pt single atoms at a potential of 0.5-1.0 V (vs. RHE); The Pt single atoms are uniformly fixed on the surface of the carbon coating layer by electrochemical deposition method, and the loading of the Pt single atoms is 0.02-0.1 mg / cm 2 , hydrogen evolution overpotential ≤30 mV@10 mA / cm 2 ; The acetylene pyrolysis carbon coating layer provides high specific surface area and corrosion resistance.
[0029] (3) Membrane electrode assembly, stack the anode, AEM membrane and cathode, hot press at 0.5-1.5 MPa, 60-100℃ for 3-10 minutes to obtain a composite membrane electrode with an interface resistance of ≤3 mΩ·cm 2 , and the thickness of the AEM membrane is 90 μm.
[0030] Example 1 A method for preparing a high-efficiency membrane electrode based on single-atom catalyst, comprising the following steps: (1) Anode preparation Put the foamed nickel (4×4 cm 2 and 0.4 mm thick, porosity 90%) in 100 mL ethanol / acetone solution (volume ratio of ethanol to acetone is 3:1) and ultrasonic for 30 minutes at 40℃ to remove oil stains on the surface of the foamed nickel; Then ultrasonic cleaning in 3.0M HCl solution for 20 minutes to remove the surface oxide layer, ready for use; Take 18 mmol of Ni(NO3)2, 6 mmol of Fe(NO3)3 and 3 mmol of MoO3 respectively, dissolve them in 80 mL of deionized water, and make a NiFeMo precursor mixed solution after ultrasonic treatment for 20 minutes; Subsequently, the treated foam nickel is immersed in the NiFeMo precursor mixed solution, vacuum impregnated at 70℃ for 2 hours, and then the impregnated foam nickel is washed with deionized water and ethanol and naturally cooled to room temperature, thereby obtaining the foam nickel loaded with NiFeMo, and the loading amount of NiFeMo is 0.2 mg / cm 2 Washing the impregnated foam nickel with deionized water and ethanol can effectively wash the surface of the impregnated foam nickel, thereby facilitating the improvement of the rate and stability of the subsequent reaction, and further improving the performance and stability of the hydrogen evolution electrode.
[0031] Take 12 mL of ethylene glycol and 1.5 g of urea, respectively, and ultrasonically stir the urea and ethylene glycol at 60℃ for 1 hour until the urea is completely dissolved, thereby obtaining a nitrogen-doped carbon coating layer precursor solution.
[0032] The foam nickel loaded with NiFeMo is placed in a crucible and placed in the center of a tube furnace, and the nitrogen-doped carbon coating layer precursor solution is poured into the crucible and placed at the gas inlet of the tube furnace. Under the protection of N2 atmosphere, the temperature is raised to 500℃ at a rate of 5℃ / min, and annealed at 500℃ for 1 hour. When the temperature in the tube furnace rises, the N2 gas flow with nitrogen-doped ethylene glycol vapor is blown onto the foam nickel loaded with NiFeMo at a flow rate of 70 mL / min, and the nitrogen-doped ethylene glycol vapor is deposited on the surface of the foam nickel loaded with NiFeMo. After annealing, the temperature of the tube furnace is reduced to room temperature, and the whole process is kept flowing with N2, thereby obtaining the positive electrode, and the thickness of the nitrogen-doped carbon coating layer is 1.5 nm.
[0033] (2) Cathode preparation The nickel felt is placed in a reaction kettle, 0.5 L / min of air and 1.0 L / min of N2 are introduced into the reaction kettle, and the introduction time is 1 hour. The reaction kettle is vacuumized to make the pressure in the kettle reach-19 KPa, and acetylene is introduced into the reaction kettle, and the flow rate of acetylene is 3.8 L / min. When the pressure in the kettle reaches one standard atmosphere, the introduction of acetylene is stopped, and the temperature is raised to 750℃. Acetylene is pyrolyzed into carbon and hydrogen, and the pressure in the kettle begins to decrease. When the pressure in the reaction kettle no longer changes, repeat the above steps until the cumulative time of the carbon coating layer reaches 2 hours, and the nickel felt with a carbon coating layer on the surface is obtained, and the thickness of the carbon coating layer is 6 μm.
[0034] Electrochemical deposition of Pt monolayer was carried out at room temperature with a platinum substrate as cathode and a pure platinum wire as anode in an aqueous solution containing 0.006 mol / L chloroplatinic acid and 1 mol / L hydrochloric acid, and Pt monolayer was deposited at a potential of 0.8 V (vs. RHE) for 30 minutes, and the Pt loading was 0.05 mg / cm 2 .
[0035] (3) Membrane electrode assembly: The anode, AEM membrane (thickness 90 μm) and cathode were stacked and hot-pressed at a pressure of 1.0 MPa and a temperature of 80℃ for 5 minutes to obtain a membrane electrode, and the interfacial resistance of the membrane electrode was 2.8 mΩ·cm 2 .
[0036] Example 2 A method for preparing a high-efficiency membrane electrode based on a monolayer catalyst, comprising the following steps: (1) Anode preparation A piece of foamed nickel (4×4 cm 2 with a thickness of 0.3 mm and a porosity of 85%) was placed in 100 mL of an ethanol / acetone solution (volume ratio of ethanol to acetone was 3:1) and ultrasonicated at 40℃ for 30 minutes to remove oil stains on the surface of the foamed nickel; then it was ultrasonicated in a 3.0M HCl solution for 20 minutes to remove the surface oxide layer, and was ready for use; 18 mmol of Ni(NO3)2, 6 mmol of Fe(NO3)3 and 3 mmol of MoO3 were weighed respectively and dissolved in 80 mL of deionized water to prepare a NiFeMo precursor mixed solution, and the solution was ultrasonicated for 20 minutes; The foamed nickel ready for use after treatment was immersed in the NiFeMo precursor mixed solution, and vacuum impregnated at 60℃ for 2 hours; then the impregnated foamed nickel was washed with deionized water and ethanol and naturally cooled to room temperature to obtain foamed nickel loaded with NiFeMo, and the loading of NiFeMo was 0.1 mg / cm 2 Washing the impregnated foamed nickel with deionized water and ethanol can effectively wash the surface of the impregnated foamed nickel, which facilitates the improvement of the rate and stability of the subsequent reaction, and thus improves the performance and stability of the hydrogen evolution electrode.
[0037] Ethylene glycol was used as a carbon source and urea was used as a nitrogen source, 12 mL of ethylene glycol and 1.5 g of urea were taken respectively, and the urea and ethylene glycol were ultrasonicated and stirred at 60℃ for 1 hour until the urea was completely dissolved to obtain a nitrogen-doped carbon coating precursor solution.
[0038] The NiFeMo-loaded nickel foam was placed in a crucible in the center of a tube furnace, and the nitrogen-doped carbon coating precursor solution was poured into the crucible and placed at the gas inlet of the tube furnace. Under a N2protective atmosphere, the temperature was raised to 400°C at a rate of 5°C / min, and annealed at 400°C for 1 hour. When the temperature in the tube furnace was raised, N2gas with nitrogen-doped ethylene glycol vapor was blown onto the NiFeMo-loaded nickel foam at a flow rate of 70 mL / min, and the nitrogen-doped ethylene glycol vapor was deposited on the surface of the NiFeMo-loaded nickel foam. After annealing, the temperature of the tube furnace was reduced to room temperature, and the process was maintained under a N2flow, thereby preparing the positive electrode. The thickness of the nitrogen-doped carbon coating was 1.0 nm.
[0039] (2) Cathode preparation The nickel felt was placed in a reaction kettle, and 0.5 L / min of air and 1.0 L / min of N2were introduced into the reaction kettle for 1 hour. The reaction kettle was vacuumized to a pressure of -19 KPa, and acetylene was introduced into the reaction kettle at a flow rate of 3.8 L / min. When the pressure in the kettle reached one standard atmosphere, the introduction of acetylene was stopped, and the temperature was raised to 700°C. Acetylene was pyrolyzed into carbon and hydrogen, and the pressure in the kettle began to decrease. When the pressure in the reaction kettle no longer changed, the above steps were repeated, and the deposition time reached 2 hours. The nickel felt with a carbon coating on the surface was obtained, and the thickness of the carbon coating was 5 μm.
[0040] At room temperature, platinum substrate was used as the cathode, and pure platinum wire was used as the anode. Electrochemical deposition was carried out in an aqueous solution containing 0.006 mol / L chloroplatinic acid and 1 mol / L hydrochloric acid. Pt monatomic was electrochemically deposited at a potential of 0.5 V (vs. RHE), and the deposition time was 30 minutes. The Pt loading was 0.02 mg / cm 2 .
[0041] (3) Membrane electrode assembly The anode, AEM membrane (thickness 90 μm), and cathode were stacked and hot-pressed at a pressure of 0.5 MPa and a temperature of 60°C for 10 minutes to prepare a membrane electrode. The interfacial resistance of the membrane electrode was 2.5 mΩ·cm 2 .
[0042] Example 3 A method for preparing a high-efficiency membrane electrode based on a single-atom catalyst, comprising the following steps: (1) Anode preparation A nickel foam (4×4 cm 2and the thickness is 0.5 mm and the porosity is 95%) is placed in 100 mL of an ethanol / acetone solution (the volume ratio of ethanol to acetone is 3:1) and is ultrasonically cleaned at 40°C for 30 minutes to remove oil stains on the surface of the foamed nickel; then the foamed nickel is placed in a 3.0M HCl solution and is ultrasonically cleaned for 20 minutes to remove the surface oxide layer, and is ready for use; 18 mmol of Ni(NO3)2, 6 mmol of Fe(NO3)3 and 3 mmol of MoO3 are respectively weighed and dissolved in 80 mL of deionized water to prepare a NiFeMo precursor mixed solution after ultrasonic cleaning for 20 minutes; The foamed nickel ready for use after treatment is immersed in the NiFeMo precursor mixed solution and is vacuum-impregnated at 80°C for 2 hours. Then the impregnated foamed nickel is washed with deionized water and ethanol and is naturally cooled to room temperature to obtain the foamed nickel loaded with NiFeMo, and the loading amount of NiFeMo is 0.3 mg / cm 2 Washing the impregnated foamed nickel with deionized water and ethanol can effectively wash the surface of the impregnated foamed nickel, which facilitates the improvement of the rate and stability of the subsequent reaction, and thus improves the performance and stability of the hydrogen evolution electrode.
[0043] Ethylene glycol is used as a carbon source and urea is used as a nitrogen source. 12 mL of ethylene glycol and 1.5 g of urea are respectively taken, and the urea and ethylene glycol are ultrasonically stirred at 60°C for 1 hour until the urea is completely dissolved to obtain a nitrogen-doped carbon coating precursor solution.
[0044] The foamed nickel loaded with NiFeMo is placed in a crucible and is placed in the center of a tube furnace. The nitrogen-doped carbon coating precursor solution is poured into another crucible and is placed at the gas inlet of the tube furnace. Under the protection of a N2 atmosphere, the temperature is raised to 600°C at a rate of 5°C / min, and is annealed at 400°C for 1 hour. When the temperature in the tube furnace is raised, N2 gas with nitrogen-doped ethylene glycol vapor is blown onto the foamed nickel loaded with NiFeMo at a flow rate of 70 mL / min, and the nitrogen-doped ethylene glycol vapor is deposited on the surface of the foamed nickel loaded with NiFeMo. After the annealing is completed, the temperature of the tube furnace is lowered to room temperature under the condition of N2 flow, and thus the positive electrode is prepared. The thickness of the nitrogen-doped carbon coating layer is 2.0 nm.
[0045] (2) Preparation of the cathode The nickel felt is placed in a reaction kettle, air and N2 with flow rates of 0.5 L / min and 1.0 L / min respectively are introduced into the reaction kettle for 1 hour. The reaction kettle is vacuumized to make the pressure in the kettle reach -19 KPa, acetylene is introduced into the reaction kettle, the acetylene flow rate is 3.8 L / min, when the pressure in the kettle reaches one standard atmosphere, the introduction of acetylene is stopped, the temperature is raised to 850℃, acetylene is pyrolyzed into carbon and hydrogen, the pressure in the kettle begins to decrease; when the pressure in the reaction kettle no longer changes, the above steps are repeated until the total time of gas phase deposition reaches 2 hours, a nickel felt with a carbon coating on the surface is obtained, and the thickness of the carbon coating is 7 μm.
[0046] Electrochemical deposition is carried out at room temperature with a platinum substrate as a cathode and a pure platinum wire as an anode in an aqueous solution containing 0.006 mol / L chloroplatinic acid and 1 mol / L hydrochloric acid, Pt monolayer is electrochemically deposited at a potential of 1.0 V (vs. RHE), the deposition time is 30 minutes, and the Pt loading is 0.1 mg / cm 2 .
[0047] (3) Membrane electrode assembly: The anode, an AEM membrane (thickness 90 μm) and the cathode are stacked, and hot pressing is performed at a pressure of 1.5 MPa and a temperature of 100℃ for 3 minutes to obtain a membrane electrode, and the interfacial resistance of the membrane electrode is 2.9 mΩ·cm 2 .
[0048] Comparative example A preparation method of a high-efficiency membrane electrode based on a monolayer catalyst, comprising the following steps: (1) Anode preparation Foamed nickel (4×4 cm 2 and a thickness of 0.5 mm and a porosity of 95%) is placed in a 100 mL ethanol / acetone solution (the volume ratio of ethanol to acetone is 3:1) and ultrasonically cleaned at 40℃ for 30 minutes to remove oil stains on the surface of the foamed nickel; then it is ultrasonically cleaned in a 3.0M HCl solution for 20 minutes to remove the surface oxide layer, and is ready for use; Ethylene glycol is used as a carbon source and urea is used as a nitrogen source, 12 mL of ethylene glycol and 1.5 g of urea are taken respectively, the urea and ethylene glycol are ultrasonically stirred at 60℃ for 1 hour, and when the urea is completely dissolved, a nitrogen-doped carbon coating precursor solution is obtained.
[0049] The nickel foam is placed in a crucible in the center of a tube furnace, and the nitrogen-doped carbon coating precursor solution is poured into another crucible, which is placed at the gas inlet of the tube furnace. Under the protection of N2 atmosphere, the temperature is raised to 600℃ at a rate of 5 ℃ / min, and annealed at 400℃ for 1 hour. When the temperature in the tube furnace rises, the N2 gas stream with nitrogen-doped ethylene glycol vapor is blown onto the nickel foam at a flow rate of 70 mL / min, and the nitrogen-doped ethylene glycol vapor is deposited on the surface of the nickel foam. After annealing, the temperature of the tube furnace is reduced to room temperature, and the N2 flow is maintained throughout the process, thereby preparing the positive electrode. The thickness of the nitrogen-doped carbon coating is 2.0 nm.
[0050] (2) Cathode preparation The nickel felt is placed in a reaction kettle, and air and N2 are introduced into the reaction kettle at flow rates of 0.5 L / min and 1.0 L / min, respectively, for 1 hour. The reaction kettle is vacuumed to a pressure of -19 KPa, and acetylene is introduced into the reaction kettle at a flow rate of 3.8 L / min. When the pressure in the kettle reaches one atmosphere, the introduction of acetylene is stopped, and the temperature is raised to 850℃. Acetylene pyrolysis produces carbon and hydrogen gas, and the pressure in the kettle begins to decrease. When the pressure in the reaction kettle no longer changes, repeat the above steps until the gas phase deposition time reaches 2 hours, obtaining a nickel felt with a carbon coating on the surface, and the carbon coating has a thickness of 7 μm.
[0051] At room temperature, platinum substrate is used as the cathode, and pure platinum wire is used as the anode for electrochemical deposition in an aqueous solution containing 0.006 mol / L chloroplatinic acid and 1 mol / L hydrochloric acid. Pt monolayer is electrochemically deposited at a potential of 1.0 V (vs. RHE) for 30 minutes, and the Pt loading is 0.1 mg / cm 2 .
[0052] (3) Membrane electrode assembly: The anode, AEM membrane (thickness 90 μm) and cathode are stacked and hot-pressed at a pressure of 1.5 MPa and a temperature of 100℃ for 3 minutes to obtain a membrane electrode. The interfacial resistance of the membrane electrode is 2.9 mΩ·cm 2 .
[0053] Performance test and analysis The stability test is performed using a proton exchange membrane electrolysis water test device.
[0054] The membrane electrode prepared in Example 1 has a cell voltage of 1.78 V@2 A / cm 2 , an overpotential of 310 mV@2 A / cm 2 , and a stable operation of 1000 hours@3 A / cm 2 .
[0055] The membrane electrode prepared in Example 2 has a cell voltage of 1.82 V@2 A / cm under the condition of 1 M KOH and 80℃ 2 , an overpotential of 320 mV@2 A / cm 2 , and can be stably operated for 1200 hours@3 A / cm 2 .
[0056] The membrane electrode prepared in Example 3 has a cell voltage of 1.75 V@2 A / cm under the condition of 1 M KOH and 80℃ 2 , an overpotential of 300 mV@2 A / cm 2 , and can be stably operated for 1500 hours@3 A / cm 2 .
[0057] The membrane electrode prepared in the comparative example has a cell voltage of 1.78 V@2 A / cm under the condition of 1 M KOH and 80℃ 2 , an overpotential of 320 mV@2 A / cm 2 , and can be stably operated for 600 hours@3 A / cm 2 .
[0058] The membrane electrode can be stably operated for 1000 hours under the industrial current density (3 A / cm 2 ), and the production cost of hydrogen is as low as 1.5 dollars / kg, which is suitable for large-scale green hydrogen production.
[0059] The present application significantly improves the activity, stability and interface conductivity of the membrane electrode by combining the in-situ loading of single-atom catalysts with the membrane electrode hot pressing process, which is suitable for industrial green hydrogen production and has a broad market application prospect. The preparation method of the present application is simple, easy to operate and implement.
[0060] In the present application, the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples.
[0061] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.
Claims
1. A high-efficiency membrane electrode based on a single-atom catalyst, characterized in that: include: For the anode, the surface of nickel foam was loaded with NiFeMo single-atom catalyst by wet chemical impregnation, and then loaded with nitrogen-doped carbon coating by vapor deposition; At the cathode, a carbon coating was deposited on the surface of nickel felt by acetylene pyrolysis, and Pt single atoms were fixed by electrochemical deposition.
2. The high-efficiency membrane electrode based on single-atom catalyst according to claim 1, characterized in that The thickness of the nickel foam is 0.3-0.5 mm, and the porosity is 80-95%.
3. The high-efficiency membrane electrode based on single-atom catalyst according to claim 2, characterized in that: The thickness of the nitrogen-doped carbon coating layer is 1 to 2 nm, and the loading of the NiFeMo single-atom catalyst is 0.1 to 0.3 mg / cm 2 .
4. The high-efficiency membrane electrode based on single-atom catalyst according to claim 1, characterized in that The thickness of the nickel felt is 0.2-0.4 mm, the acetylene pyrolytic carbon coating is deposited at 700-900° C., and the Pt single atom is fixed at a potential of 0.5-1.0 V vs. RHE by electrochemical deposition.
5. The high-efficiency membrane electrode based on single-atom catalyst according to claim 4, characterized in that: The thickness of the acetylene pyrolysis deposited carbon coating is 5-7 μm, and the loading of the Pt single atom is 0.02-0.1 mg / cm 2 .
6. The method for preparing a high-efficiency membrane electrode based on a single-atom catalyst according to any one of claims 1 to 5, characterized in that: The following steps are involved: (1) Anode preparation: immersing nickel foam in a mixed solution of precursors containing Ni, Fe, and Mo, followed by ultrasonic dispersion and vacuum impregnation to obtain nickel foam loaded with NiFeMo. Then, a carbon source and a nitrogen source are mixed, annealed in a N2 (nitrogen) atmosphere, and purged with N2 to form a nitrogen-doped carbon coating on the nickel foam loaded with NiFeMo; (2) Cathode preparation: a carbon coating with a thickness of 5 to 7 μm was deposited on the surface of nickel felt by acetylene pyrolysis; Pt single atoms were electrochemically deposited at a potential of 0.5 to 1.0 V vs. RHE, with a Pt single atom loading of 0.02 to 0.1 mg / cm 2 ; (3) Membrane electrode assembly: stack the anode, AEM membrane, and cathode, and use hot pressing to obtain an interface resistance of ≤3 mΩ·cm 2 composite membrane electrode.
7. The method for preparing a high-efficiency membrane electrode based on a single-atom catalyst according to claim 6, characterized in that: In step (1), Ni(NO3)2, Fe(NO3)3 and MoO3 are dissolved in pure water and mixed evenly, and then ultrasonically dispersed after adding nickel foam, vacuum impregnated at 60-80°C, and rinsed to obtain nickel foam loaded with NiFeMo, ethylene glycol is used as a carbon source and urea is used as a nitrogen source, urea and ethylene glycol are mixed, and then annealed at 400-600°C in a N2 atmosphere, purged with N2, and a nitrogen-doped carbon coating layer is formed on the nickel foam loaded with NiFeMo, wherein the molar ratio of Ni, Fe and Mo is 3:1:0.5; and the mass volume ratio of urea to ethylene glycol is 1 g:8 mL.
8. The method for preparing a high-efficiency membrane electrode based on a single-atom catalyst according to claim 6, characterized in that: In step (2), the acetylene pyrolytic carbon coating is deposited at 700-900°C.
9. The method for preparing a high-efficiency membrane electrode based on a single-atom catalyst according to claim 6, characterized in that: In step (3), the anode, the AEM membrane and the cathode are stacked in sequence and hot pressed at 0.5-1.5 MPa and 60-100° C. for 3-10 minutes to obtain a composite membrane electrode, wherein the thickness of the AEM membrane is 90 μm.
10. The use of a high-efficiency membrane electrode based on a single-atom catalyst according to any one of claims 1 to 5, characterized in that: The composite membrane electrode is used in an anion exchange membrane water electrolyzer.