Oxygen evolution catalyst for anion exchange membrane water electrolysis hydrogen production as well as preparation method and application of oxygen evolution catalyst

Abstract

The invention provides an oxygen evolution catalyst for anion exchange membrane water electrolysis hydrogen production as well as a preparation method and application of the oxygen evolution catalyst. The oxygen evolution catalyst is prepared from the following raw materials: ferric salt, nickel salt and an interlayer modifier, the interlayer modifier is urea. According to the invention, specific types of interlayer catalysts are adopted, so that the oxygen evolution catalyst has high specific surface area and more catalytic active sites, and the catalytic activity and stability of the oxygen evolution catalyst are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of catalysts, and in particular relates to an oxygen evolution catalyst for anion exchange membrane water electrolysis to produce hydrogen, and a preparation method and application thereof. Background Art

[0002] AEM (anion exchange membrane) water electrolysis technology is one of the current research hotspots in the field of green energy. It provides a clean energy conversion pathway for achieving a hydrogen economy by producing hydrogen through water electrolysis. In this process, the anode catalyst is an important part of decomposing water into oxygen and hydrogen. Traditional anode catalysts are mostly precious metal oxides, such as iridium (Ir) and ruthenium (Ru) oxides, which perform well in water electrolysis reactions due to their high activity and stability. However, precious metal resources are scarce and expensive, which limits their widespread application, especially in large-scale industrial production.

[0003] To overcome this problem, researchers have begun to focus on non-precious metal catalysts, such as transition metal oxides and hydroxides. These materials are not only low-cost, but also abundant in resources and have the potential to replace precious metal catalysts. At present, the research focus of non-precious metal catalysts is on improving the activity and stability of catalysts, as well as improving their corrosion resistance in electrolytic water. Strategies such as heterogeneous catalyst design, single-atom catalyst preparation, and the use of carbon materials or conductive polymers as catalyst supports are widely adopted. These methods aim to improve the specific surface area, dispersibility and conductivity of catalysts. Despite this, there are still challenges in the stability of non-precious metal catalysts in long-term operation, corrosion resistance under alkaline conditions, and cost control. Summary of the invention

[0004] In view of this, the object of the present invention is to provide an oxygen evolution catalyst for anion exchange membrane water electrolysis to produce hydrogen and a preparation method and application thereof, wherein the oxygen evolution catalyst has a high specific surface area, many catalytic active sites and good stability.

[0005] The present invention provides an oxygen evolution catalyst for producing hydrogen by electrolysis of water using an anion exchange membrane. The raw materials for preparing the catalyst include:

[0006] Iron salts, nickel salts and interlayer modifiers;

[0007] The interlayer modifier is urea.

[0008] Preferably, the total amount of iron ions in the iron salt and nickel ions in the nickel salt to the amount of the interlayer modifier is 1:5.8-6.2.

[0009] Preferably, the molar ratio of the iron salt to the nickel salt is 1:2.6-3.5.

[0010] Preferably, the iron salt is selected from ferric nitrate and / or ferric chloride;

[0011] The nickel salt is selected from nickel nitrate.

[0012] The present invention provides a method for preparing an oxygen evolution catalyst for anion exchange membrane water electrolysis to produce hydrogen as described in the above technical solution, comprising the following steps:

[0013] Dissolving iron salt and nickel salt in water and mixing them evenly to obtain an iron-nickel precursor solution;

[0014] Mixing the iron-nickel precursor solution and the interlayer modifier to obtain a mixed solution;

[0015] subjecting the mixed solution to a hydrothermal reaction to obtain a reaction product;

[0016] After the reaction product is cooled, the obtained precipitate is washed and dried to obtain an oxygen evolution catalyst for hydrogen production by anion exchange membrane water electrolysis.

[0017] Preferably, the hydrothermal reaction is first carried out at 115 to 125° C. for 115 to 125 minutes;

[0018] Then react at 145-155°C for 230-250 minutes.

[0019] The present invention provides a FeNi-LDH / nickel felt anode, and the raw materials for preparing the anode include:

[0020] The oxygen evolution catalyst for producing hydrogen by electrolysis of water using anion exchange membrane as described in the above technical solution;

[0021] Conductive agent, dispersant, binder and water.

[0022] Preferably, the mass ratio of the dispersant, water, binder, oxygen evolution catalyst and conductive agent is (420-430):(34-38):(22-26):(4.6-5.0):1.

[0023] Preferably, the dispersant is isopropanol and / or acetone;

[0024] The conductive agent is carbon powder;

[0025] The binder is nafion ionomer or Fuma ionomer.

[0026] The present invention provides a method for preparing the FeNi-LDH / nickel felt anode described in the above technical solution, comprising the following steps:

[0027] The FeNi-LDH catalyst powder, a conductive agent, a dispersant, a binder and water are mixed to obtain a slurry;

[0028] The slurry is sprayed on the pretreated surface of the nickel felt to obtain a FeNi-LDH / nickel felt anode.

[0029] The present invention provides an oxygen evolution catalyst for hydrogen production by water electrolysis using anion exchange membrane, wherein the raw materials for preparation include: iron salt, nickel salt and interlayer modifier; the interlayer modifier is urea. The present invention adopts a specific type of interlayer catalyst, so that the oxygen evolution catalyst has a high specific surface area and more catalytic active sites, thereby improving its catalytic activity and stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic diagram of the process of preparing a FeNi-LDH / nickel felt anode in a specific embodiment of the present invention;

[0031] Figure 2 This is a SEM image of the oxygen evolution catalyst for hydrogen production by electrolysis of water using an anion exchange membrane prepared in Example 1 of the present invention;

[0032] Figure 3 This is the BET diagram of the FeNi-LDH powder prepared in Example 1 of the present invention;

[0033] Figure 4 is the BET diagram of commercial NiFeMo;

[0034] Figure 5 This is a curve diagram showing the change of voltage versus current at a constant temperature for the electrode prepared in Example 1 of the present invention;

[0035] Figure 6 The stability test results of the electrode prepared in Example 1 of the present invention;

[0036] Figure 7 The stability test results of the electrode prepared in Example 2 of the present invention;

[0037] Figure 8 The stability test results of the electrode prepared in Comparative Example 1 of the present invention;

[0038] Fig. 9 This is a stability test diagram of the electrode prepared in Comparative Example 2 of the present invention. DETAILED DESCRIPTION

[0039] The present invention provides an oxygen evolution catalyst for producing hydrogen by electrolysis of water using an anion exchange membrane. The raw materials for preparing the catalyst include:

[0040] Iron salts, nickel salts and interlayer modifiers;

[0041] The interlayer modifier is urea.

[0042] The oxygen evolution catalyst provided by the present invention has a higher specific surface area and more catalytic active sites. When used in the anode, the voltage required for the obtained battery to reach a current density of 2A is smaller, and the performance is better; it has smaller voltage attenuation and better stability.

[0043] The raw materials for preparing the oxygen evolution catalyst for hydrogen production by anion exchange membrane water electrolysis provided by the present invention include iron salt; the iron salt is selected from iron nitrate and / or iron chloride;

[0044] The raw materials for preparing the oxygen evolution catalyst for producing hydrogen through water electrolysis by anion exchange membrane provided by the present invention include nickel salt; the nickel salt is selected from nickel nitrate.

[0045] The raw materials for preparing the oxygen evolution catalyst for producing hydrogen by electrolysis of water using an anion exchange membrane provided by the present invention include an interlayer modifier; the interlayer modifier is urea.

[0046] The molar ratio of the total amount of iron ions in the iron salt and the nickel ions in the nickel salt to the interlayer modifier of the present invention is 1:5.8-6.2, specifically 1:5.8, 1:5.9, 1:6.0, 1:6.1 or 1:6.2; in a specific embodiment, the molar ratio of the total amount of iron ions in the iron salt and the nickel ions in the nickel salt to the interlayer modifier is 1:6.

[0047] The present invention provides a method for preparing an oxygen evolution catalyst for anion exchange membrane water electrolysis to produce hydrogen as described in the above technical solution, comprising the following steps:

[0048] Dissolving iron salt and nickel salt in water and mixing them evenly to obtain an iron-nickel precursor solution;

[0049] Mixing the iron-nickel precursor solution and the interlayer modifier to obtain a mixed solution;

[0050] subjecting the mixed solution to a hydrothermal reaction to obtain a reaction product;

[0051] After the reaction product is cooled, the obtained precipitate is washed and dried to obtain an oxygen evolution catalyst for hydrogen production by anion exchange membrane water electrolysis.

[0052] The present invention dissolves an iron salt and a nickel salt in water, mixes them evenly, and obtains an iron-nickel precursor solution. The present invention uniformly mixes the iron salt and the nickel salt in water by ultrasound and stirring. The molar ratio of the iron salt to the nickel salt is 1:2.6 to 3.5, specifically 1:2.6, 1:2.7, 1:2.8, 1:2.9, 1:3.0, 1:3.1, 1:3.2, 1:3.3, 1:3.4 or 1:3.5; in a specific embodiment, the molar ratio of the iron salt to the nickel salt is 1:2.8 or 1:3.5.

[0053] The present invention mixes the iron-nickel precursor solution and the interlayer modifier to obtain a mixed solution. The interlayer modifier is urea. The total amount of iron ions in the iron salt and nickel ions in the nickel salt to the amount of the interlayer modifier is 1:5.8 to 6.2, specifically 1:5.8, 1:5.9, 1:6.0, 1:6.1 or 1:6.2; in a specific embodiment, the total amount of iron ions in the iron salt and nickel ions in the nickel salt to the amount of the interlayer modifier is 1:6.

[0054] The present invention conducts a hydrothermal reaction on the mixed solution to obtain a reaction product. The present invention can control the growth process of the layered hydroxide by controlling the temperature and time of the hydrothermal reaction, so as to improve the activity and stability of the catalyst. The temperature of the hydrothermal reaction is 115-155°C, and the time is 5.5-6.5h; the hydrothermal reaction is preferably first reacted at 115-125°C for 115-125min; and then reacted at 145-155°C for 230-250min. In a specific embodiment, the hydrothermal reaction is first reacted at 120°C for 120min, and then reacted at 150°C for 240min; or reacted at 150°C for 6h.

[0055] The present invention provides a FeNi-LDH / nickel felt anode, and the raw materials for preparing the anode include:

[0056] The oxygen evolution catalyst for hydrogen production by water electrolysis using anion exchange membrane as described in the above technical solution;

[0057] Conductive agent, dispersant, binder and water.

[0058] In the present invention, the conductive agent is selected from carbon powder; the dispersant is selected from ethanol and / or isopropanol; the adhesive is selected from nafion ionomer or Fuma ionomer; in a specific embodiment, the adhesive is nafion ionomer D-520, with a resin content of 5wt.%.

[0059] The mass ratio of the dispersant, water, binder, oxygen evolution catalyst and conductive agent in the present invention is (420-430): (34-38): (22-26): (4.6-5.0): 1, and more preferably (424-427): (35-37): (23-25): (4.7-4.9): 1; in a specific embodiment, the mass ratio of isopropanol, water, nafion, oxygen evolution catalyst and conductive agent is 425:36:24:4.8:1.

[0060] The FeNi-LDH / nickel felt anode provided by the present invention is easy to prepare, can be expanded for production, has high performance in electrocatalytic water decomposition, has a small voltage decay amplitude, and has good electrode stability. Under constant current conditions, the amplitude of voltage decay (ΔV) directly reflects the polarization degree of the electrochemical system, and polarization is the core source of energy loss and performance degradation. Simply put, the smaller the voltage decay amplitude, the better the stability of the electrode.

[0061] The present invention provides a method for preparing the FeNi-LDH / nickel felt anode described in the above technical solution, comprising the following steps:

[0062] The FeNi-LDH catalyst powder, a conductive agent, a dispersant, a binder and water are mixed to obtain a slurry;

[0063] The slurry is sprayed on the pretreated surface of the nickel felt to obtain a FeNi-LDH / nickel felt anode.

[0064] The present invention preferably adopts ultrasonic mixing to uniformly mix the FeNi-LDH catalyst powder, the conductive agent, the dispersant, the adhesive and the water.

[0065] After obtaining the slurry, the present invention evenly sprays the slurry on the surface of the pretreated nickel felt through an ultrasonic sprayer; the pretreated nickel felt is cleaned by alcohol and hydrochloric acid in sequence, and then hot-pressed and flattened at 100° C. and a force of 2 tons. The present invention calculates the loading amount of the catalyst according to the mass before and after spraying, and the ultrasonic sprayer has a heating function and does not need to be dried.

[0066] The electrode material provided by the present invention is easy to recoat and regenerate, can reduce maintenance costs and downtime, and improve the service life and economic benefits of the electrode. The present invention can improve the mechanical strength and flexibility of the electrode material, making it more suitable for various electrolyzer designs, especially in the assembly process of AEM electrolyzers that require uniform thickness.

[0067] Figure 1The process of preparing the FeNi-LDH / nickel felt anode according to the embodiment of the present invention comprises: S1, dissolving a certain proportion of iron salt and nickel salt in deionized water, and obtaining a uniform nickel-iron precursor solution by ultrasound and stirring; S2, adding a precipitant and an interlayer modifier to the nickel-iron precursor solution, performing secondary ultrasound and stirring treatment, and obtaining a mixed solution; S3, adding the mixed solution to a hydrothermal reactor, and setting conditions such as the hydrothermal reaction temperature and reaction time; S4, after the hydrothermal reaction is completed, the reactor is cooled to room temperature, and a turbid liquid is obtained. After the supernatant is poured out, the remaining particle layer is washed with water / alcohol for multiple times, and the FeNi-LDH catalyst powder is obtained after vacuum drying; S5, the FeNi-LDH catalyst powder, a conductive agent, a dispersant, a binder and deionized water are mixed and ultrasonically homogenized for a long time to obtain a uniform slurry; S6, the dispersed slurry is evenly sprayed on the surface of the pretreated nickel felt by ultrasound to obtain a FeNi-LDH / nickel felt anode.

[0068] The process provided by the present invention is simple, the preparation cost is low, and it is convenient for large-scale production; the content and distribution of the powdered material in the electrode can be adjusted as needed, which provides greater flexibility for electrode design; the powdered material has better dispersibility and is more uniform after spraying, which can have better contact with the membrane, reduce contact resistance, and ensure the overall uniformity of the electrolytic cell.

[0069] To further illustrate the present invention, an oxygen evolution catalyst for producing hydrogen by electrolysis of water using an anion exchange membrane and its preparation method and application provided by the present invention are described in detail below in conjunction with embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0070] Example 1

[0071] Dissolving iron nitrate and nickel nitrate in deionized water at a molar ratio of 1:2.8, and obtaining a uniform iron-nickel precursor solution by ultrasonication and stirring;

[0072] Adding urea to the iron-nickel precursor solution, with the molar ratio of metal ions to urea being 1:6, and performing secondary ultrasonic and stirring treatment to obtain a mixed solution;

[0073] The mixed solution is added to a hydrothermal reactor, and the reaction is first carried out at 120° C. for 2 hours, and then at 150° C. for 4 hours. After the hydrothermal reaction is completed, the reactor is cooled to room temperature to obtain a turbid liquid. After the upper clear liquid is poured out, the remaining particle layer is alternately washed with deionized water and ethanol for multiple times, and vacuum dried to obtain FeNi-LDH catalyst powder as an oxygen evolution catalyst;

[0074] The FeNi-LDH catalyst powder, conductive agent (carbon powder), dispersant (isopropanol), binder (nafion solution) and deionized water were mixed and homogenized by ultrasonic for 1 hour to obtain a uniform slurry; the mass ratio of isopropanol, water, nafion ionomer, oxygen evolution catalyst and conductive agent was 425:36:24:4.8:1;

[0075] The nickel felt was cleaned in turn with alcohol and hydrochloric acid, and then hot pressed and flattened at 100°C and a force of 2t to obtain a pretreated nickel felt; the dispersed slurry was evenly sprayed on the surface of the pretreated nickel felt by an ultrasonic sprayer to obtain a FeNi-LDH / nickel felt anode.

[0076] Figure 2 The SEM image of the FeNi-LDH catalyst powder prepared in Example 1 of the present invention; Figure 2 It can be seen that a small part of them presents two-dimensional nanosheets, while most of them are stacked with bent nanorods to form a layered structure.

[0077] Figure 3 This is the BET diagram of the FeNi-LDH powder prepared in Example 1 of the present invention; Figure 4 This is the BET diagram of commercial NiFeMo. It can be seen that the specific surface area of ​​FeNi-LDH powder is 51.189m 2 g -1 ; The specific surface area of ​​commercial NiFeMo is 2.554m 2 g -1 .

[0078] The present invention adopts a constant current electrolysis method to test the voltage required to achieve a current density of 2A.

[0079] Using commercial NiFeMo as a control, the results are shown in Figure 5 It can be seen that the catalyst prepared by the present invention requires a smaller voltage of only 1.84V to reach 2A under the same spraying conditions, and has better performance.

[0080] The present invention adopts a constant current electrolysis method to test the stability of the catalyst on the AEM water electrolysis test instrument of Xiamen Ludao Hydrogen Energy.

[0081] Figure 6 The stability test results of the electrode prepared in Example 1 were tested for 72 hours at a test current of 1A. It was found that the NiFe-LDH-nickel felt anode voltage finally stabilized between 1.78V-1.8V, with a voltage attenuation degree ΔV of 0.53mV / h, and better stability. The NiFeMo-nickel felt anode voltage finally stabilized between 1.8V-2.1V, with a voltage attenuation degree ΔV of 2.4mV / h.

[0082] Example 2

[0083] Dissolve iron nitrate and nickel nitrate in deionized water at a molar ratio of 1:3.5, and obtain a uniform iron-nickel precursor solution by ultrasonication and stirring;

[0084] Adding urea to the iron-nickel precursor solution, with the molar ratio of metal ions to urea being 1:6, and performing secondary ultrasonic and stirring treatment to obtain a mixed solution;

[0085] The mixed solution was added to a hydrothermal reactor and reacted at 150° C. for 6 hours. After the hydrothermal reaction was completed, a turbid liquid was obtained after the reactor was cooled to room temperature. After the upper clear liquid was poured out, the remaining particle layer was washed alternately with deionized water and ethanol for multiple times, and then vacuum dried to obtain FeNi-LDH-2 catalyst powder.

[0086] The FeNi-LDH-2 catalyst powder, conductive agent (carbon powder), dispersant, binder (nafion solution D520) and organic solvent (isopropanol) were mixed and homogenized by ultrasonic for 1 hour to obtain a uniform slurry; the mass ratio of isopropanol, water, nafion ionomer, oxygen evolution catalyst and conductive agent was 425:36:24:4.8:1;

[0087] The nickel felt was cleaned in turn with alcohol and hydrochloric acid, and then hot-pressed and flattened at 100°C and a force of 2t to obtain a pretreated nickel felt; the dispersed slurry was evenly sprayed on the surface of the pretreated nickel felt by an ultrasonic sprayer to obtain a FeNi-LDH-2 / nickel felt anode.

[0088] Figure 7 The stability test results of the FeNi-LDH-2 / nickel felt anode prepared in Example 2 of the present invention, the test time is 50h, the test current is 1A; Figure 7 It can be seen that the catalyst prepared by the present invention has a smaller voltage decay, which is stable between 2.0-2.2V, and the voltage decay degree ΔV is 4.4mV / h, and the stability is good.

[0089] Comparative Example 1

[0090] On the basis of Example 1, urea was replaced by ammonium fluoride, the molar ratio of metal ion to ammonium fluoride was 1:6, and other parameters remained unchanged. The prepared electrode was recorded as FeNi-LDH-3 / nickel felt anode.

[0091] Figure 8 The stability test results of the FeNi-LDH-3 / nickel felt anode prepared in Comparative Example 1 of the present invention are shown in FIG. 1 , wherein the test time is 30 hours and the test current is 1A; Figure 8It can be seen that the catalyst prepared with ammonium fluoride as the interlayer modifier has a voltage stable at 2.2V at a constant current density of 1A, a voltage attenuation degree ΔV of 7mV / h, and a significantly attenuated water electrolysis performance compared to Example 1.

[0092] Comparative Example 2

[0093] On the basis of the unchanged molar ratio of nickel and iron metals in Example 1, 10%, 18% and 20% of cobalt nitrate were added respectively, and the other conditions remained unchanged.

[0094] The stability test results of the prepared electrodes are shown in Fig. 9 .Depend on Fig. 9 It can be seen that under the condition of constant current 1A, the stability of the three NiFeCo-LDH catalysts varies: NiFeCo-LDH (10% Co) initially drops in voltage, then enters a stable stage, with small fluctuations in the middle stage; NiFeCo-LDH (18% Co) initially fluctuates in voltage, tends to stabilize after 2 hours, and then rises again in the later stage; NiFeCo-LDH (20% Co) voltage continues to rise over time, especially after 5 hours, the rise accelerates. In general, NiFeCo-LDH (10% Co) and (18% Co) have better stability in some periods, among which 10% Co has a longer stable period, while 20% Co has the worst stability and more significant performance attenuation: NiFe-LDH (10% Co)-nickel felt anode voltage attenuation degree ΔV is 1.25mV / h, NiFe-LDH (18% Co)-nickel felt anode voltage attenuation degree ΔV is 2.5mV / h, and NiFe-LDH (20% Co)-nickel felt anode voltage attenuation degree ΔV is 5mV / h. However, compared with NiFe-LDH, its long-term stability is poorer, and the voltage is higher under constant current 1A conditions.

[0095] As can be seen from the above embodiments, the present invention provides an oxygen evolution catalyst for hydrogen production by water electrolysis using anion exchange membrane, the preparation raw materials comprising: iron salt, nickel salt and interlayer modifier; the interlayer modifier is urea. The present invention adopts a specific type of interlayer catalyst, so that the oxygen evolution catalyst has a high specific surface area and more catalytic active sites, thereby improving its catalytic activity and stability.

[0096] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. An oxygen evolution catalyst for anion exchange membrane water electrolysis hydrogen production, the preparation raw materials comprising: Iron salts, nickel salts and interlayer modifiers; The interlayer modifier is urea.

2. The oxygen evolution catalyst for producing hydrogen by anion exchange membrane water electrolysis according to claim 1, characterized in that: The total amount ratio of the iron ions in the iron salt and the nickel ions in the nickel salt to the amount of the interlayer modifier is 1:5.8-6.

2.

3. The oxygen evolution catalyst for producing hydrogen by anion exchange membrane water electrolysis according to claim 1, characterized in that: The molar ratio of the iron salt to the nickel salt is 1:2.6-3.

5.

4. The oxygen evolution catalyst for producing hydrogen by anion exchange membrane water electrolysis according to claim 1, characterized in that: The iron salt is selected from ferric nitrate and / or ferric chloride; The nickel salt is selected from nickel nitrate.

5. A method for preparing the oxygen evolution catalyst for hydrogen production by anion exchange membrane water electrolysis according to claim 1, comprising the following steps: Dissolving iron salt and nickel salt in water and mixing them evenly to obtain an iron-nickel precursor solution; Mixing the iron-nickel precursor solution and the interlayer modifier to obtain a mixed solution; subjecting the mixed solution to a hydrothermal reaction to obtain a reaction product; After the reaction product is cooled, the obtained precipitate is washed and dried to obtain an oxygen evolution catalyst for hydrogen production by anion exchange membrane water electrolysis.

6. The preparation method according to claim 4, characterized in that: The hydrothermal reaction is first carried out at 115-125° C. for 115-125 minutes; Then react at 145-155°C for 230-250 minutes.

7. A FeNi-LDH / nickel felt anode, the raw materials for preparation comprising: The oxygen evolution catalyst for hydrogen production by anion exchange membrane water electrolysis according to any one of claims 1 to 3; Conductive agent, dispersant, binder and water.

8. The FeNi-LDH / nickel felt anode according to claim 7, characterized in that: The mass ratio of the dispersant, water, adhesive, oxygen evolution catalyst and conductive agent is (420-430):(34-38):(22-26):(4.6-5.0):

1.

9. The FeNi-LDH / nickel felt anode according to claim 7, characterized in that: The dispersant is isopropyl alcohol and / or acetone; The conductive agent is carbon powder; The binder is nafion ionomer or Fuma ionomer.

10. A method for preparing the FeNi-LDH / nickel felt anode according to claim 7, comprising the following steps: The FeNi-LDH catalyst powder, a conductive agent, a dispersant, a binder and water are mixed to obtain a slurry; The slurry is sprayed on the pretreated surface of the nickel felt to obtain a FeNi-LDH / nickel felt anode.

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