NiFe / INF catalyst, preparation method and application

Abstract

The invention relates to the technical field of catalyst preparation, and provides a NiFe / INF catalyst and a preparation method and application thereof.The preparation method of the NiFe / INF catalyst comprises the steps that S1, a precursor solution is prepared, and the precursor solution comprises nickel salt and iron salt; s2, foam ferronickel is soaked in the precursor solution; and S3, carrying out heat treatment to prepare the NiFe / INF catalyst. According to the preparation method of the NiFe / INF catalyst, the prepared catalyst has multiple active components, all the components are tightly combined to form a unique pore channel structure, more active sites are exposed, the conductivity is improved, and the high-strength stability is achieved; besides, through the synergistic effect of different metals, the adsorption Gibbs free energy of an intermediate product can be remarkably reduced, so that the catalytic activity of the catalyst is improved, and the catalyst shows excellent OER activity and stability in alkaline electrolyzed water under the industrial-grade current density.

Description

Technical Field

[0001] The present invention relates to the technical field of catalyst preparation, and in particular to a NiFe / INF catalyst, a preparation method and an application thereof. Background Art

[0002] In the process of global energy transformation, hydrogen energy, as one of the carriers supporting energy transformation and green transformation of materials, plays an irreplaceable and important role. my country has a good hydrogen production foundation and a large-scale application market, and the hydrogen energy industry is showing a positive development trend. The technology of using renewable energy to generate electricity for alkaline water electrolysis to produce hydrogen is considered to be the most likely way to become an economical green hydrogen production method, and it is also one of the large-scale and efficient electrochemical energy storage technologies.

[0003] The main technical bottleneck of the current alkaline water electrolysis hydrogen production technology is how to reduce the energy consumption of the electrolysis process and meet the requirements of wide power fluctuations of renewable energy power supply. Among them, in the process of alkaline water electrolysis hydrogen production, the oxygen evolution reaction (OER) involving multiple proton-coupled electron transfer steps has slow kinetics and high overpotential, which has always been a problem that has plagued the field of alkaline water electrolysis hydrogen production. In addition, the OER process is also one of the key reactions in new energy technologies such as fuel cells, rechargeable metal-air batteries, and photocatalytic water splitting. The development of efficient and inexpensive anode oxygen evolution catalysts is of great significance for the large-scale application of energy conversion technologies. Among them, RuO2 and IrO2 are commonly used OER electrocatalysts, but their scarcity, high cost, and poor stability in alkaline media limit their widespread use. At present, in order to reduce the manufacturing cost of electrode materials, commercially, low-priced, large-surface-area, and stable foamed Ni and NiMo alloys are mainly used as oxygen evolution catalysts for alkaline water electrolysis hydrogen production; however, due to their low catalytic intrinsic activity, they are not very effective at high current densities (500 mA cm -2 ) requires a high overpotential (about 500 mV), resulting in excessive power consumption. Therefore, the key to achieving large-scale production of green hydrogen is to develop high-performance, low-cost, and highly active non-precious metal catalysts that can operate stably at high current density for oxygen evolution reaction, thereby reducing the power consumption and equipment cost of water electrolysis to produce hydrogen.

[0004] Currently, NiFe compounds have a suitable OER reaction energy barrier in alkaline electrolytes and are considered to be ideal alternative materials for precious metal catalysts. However, due to the serious Fe segregation problem, NiFe catalysts have poor activity and stability at high current density.

[0005] In view of this, the present invention is proposed. Summary of the invention

[0006] The purpose of the present invention is to provide a NiFe / INF catalyst, a preparation method and an application thereof, so as to solve the problem in the prior art that the NiFe catalyst has poor activity and stability at high current density due to the serious Fe segregation problem.

[0007] To achieve the above object, the technical solution of the present invention is achieved as follows: A method for preparing a NiFe / INF catalyst, comprising the following steps: S1. preparing a precursor solution, wherein the precursor solution comprises a nickel salt and an iron salt; S2, soaking the nickel iron foam in the precursor solution; S3. Heat treatment to obtain NiFe / INF catalyst.

[0008] The method for preparing the NiFe / INF catalyst of the present invention provides a catalyst having multiple active components, each of which is tightly combined to form a unique pore structure, exposing more active sites, improving electrical conductivity, and having high-strength stability; in addition, through the synergistic effect between different metals, the adsorption Gibbs free energy of the intermediate product can be significantly reduced, thereby improving the catalytic activity of the catalyst, so that the catalyst exhibits excellent OER activity and stability in alkaline electrolyzed water at industrial-grade current density.

[0009] Further, in step S2, the nickel content in the nickel-iron foam is X, the iron content in the nickel-iron foam is Y, and X:Y=1:0.43~2.33.

[0010] Further, in step S1, the nickel salt is at least one of nickel sulfate, nickel nitrate, nickel chloride, nickel acetate, and nickel sulfite. Furthermore, in step S1, the iron salt is at least one of ferric sulfate, ferrous sulfate, ferric nitrate, ferric chloride and ferrous chloride.

[0011] Furthermore, in step S1, the solvent used to prepare the precursor solution is at least one of deionized water, methanol, ethanol, and ethylene glycol.

[0012] Furthermore, in step S1, the concentration of the nickel salt in the precursor solution is 0.01-5.0 mol / L, and the concentration of the iron salt in the precursor solution is 0.01-5.0 mol / L.

[0013] Furthermore, in step S2, the nickel iron foam is immersed in the precursor solution for 0.2 to 2 hours.

[0014] Furthermore, in step S3, the heat treatment temperature is 2500-3000° C., and the heat treatment time is 10-60 s.

[0015] The second aspect of the present invention provides a catalyst prepared using any one of the above-mentioned methods for preparing a NiFe / INF catalyst.

[0016] The third aspect of the present invention provides an application of a catalyst prepared by any one of the above-mentioned methods for preparing a NiFe / INF catalyst in the field of oxygen evolution reaction by electrolysis of water.

[0017] The present invention proposes a NiFe / INF catalyst, a preparation method and an application. Compared with the prior art, the NiFe / INF catalyst, the preparation method and the application of the present invention have the following beneficial effects: 1. The NiFe / INF catalyst, preparation method and application described in the present invention use a three-dimensional porous nickel-iron foam as a substrate, and prepare a NiFe / INF catalyst composed of nanosheets with rich pores by immersing the catalyst in the precursor solution to deposit nickel salt and iron salt and combining it with a one-step rapid heat treatment method. The catalyst has multiple active components, and the components are closely combined to form a unique pore structure, exposing more active sites, improving conductivity and having high-strength stability.

[0018] 2. The NiFe / INF catalyst, preparation method and application of the present invention can significantly reduce the adsorption Gibbs free energy of the intermediate product through the synergistic effect between different metals, thereby improving the catalytic activity of the catalyst, so that it exhibits excellent OER activity and stability in alkaline electrolysis of water at an industrial current density. The NiFe / INF catalyst has a high OER activity and stability at a current density of 1000 mA cm -2 The required OER overpotential is only 197 mV, and it can operate stably for more than 800 hours, which is far superior to commercial RuO2 catalysts and has good oxygen evolution reaction stability.

[0019] 3. The NiFe / INF catalyst, preparation method and application described in the present invention have a simple preparation method, readily available raw materials, low cost, and are easy to scale up, and are expected to be applied in large-scale alkaline water electrolysis to produce hydrogen. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a SEM image of a catalyst prepared using the method for preparing a NiFe / INF catalyst described in Example 1 of the present invention; Figure 2 The XRD spectrum of the catalyst prepared by the preparation method of a NiFe / INF catalyst described in Example 1 of the present invention; Figure 3 The electrochemical performance diagram (LSV) of the oxygen evolution reaction of the catalyst prepared by the preparation method of a NiFe / INF catalyst described in the embodiment of the present invention and the comparative example; Figure 4 This is a stability test chart of the oxygen evolution reaction of the catalyst prepared by the preparation method of a NiFe / INF catalyst described in Example 1 of the present invention. DETAILED DESCRIPTION

[0021] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The descriptions of "first", "second", etc. mentioned in the embodiments of the present invention are only for descriptive purposes, and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0022] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0023] In the prior art, due to the serious Fe segregation problem, the activity and stability of NiFe catalysts at high current density are poor.

[0024] In order to solve the above technical problems, the applicant believes that alleviating the Fe segregation problem through structural optimization and active composition design is the key to improving the activity and stability of NiFe catalysts at high current density.

[0025] like Figures 1 to 4 As shown, the applicant proposes a method for preparing a NiFe / INF catalyst, and the method for preparing the NiFe / INF catalyst comprises the following steps: S1. preparing a precursor solution, wherein the precursor solution comprises a nickel salt and an iron salt; S2, soaking the nickel iron foam in the precursor solution; S3. Heat treatment to obtain NiFe / INF catalyst.

[0026] Compared with the prior art, the preparation method of a NiFe / INF catalyst described in the present invention has the following beneficial effects: The present invention discloses a method for preparing a NiFe / INF catalyst. Firstly, a three-dimensional porous nickel-iron foam is used as a substrate. A NiFe / INF catalyst composed of nanosheets with rich pores is prepared by depositing nickel salt and iron salt and combining with a one-step rapid heat treatment method. The catalyst has multiple active components. The components are tightly combined to form a unique pore structure, which exposes more active sites, improves the conductivity and has high-strength stability. Secondly, through the synergistic effect between different metals, the adsorption Gibbs free energy of the intermediate product can be significantly reduced, thereby improving the catalytic activity of the catalyst, so that the catalyst exhibits excellent OER activity and stability in alkaline electrolysis of water at an industrial-grade current density. The NiFe / INF catalyst has excellent OER activity and stability at a current density of 1000 mA cm -2 The required OER overpotential is only 197 mV, and it can operate stably for more than 800 hours, which is far superior to commercial RuO2 catalysts and has good oxygen evolution reaction stability; third, the preparation method is simple, the raw materials are easily available, the cost is low, and it is easy to scale up, and it is expected to be applied in large-scale alkaline water electrolysis to produce hydrogen.

[0027] Specifically, in step S2, the nickel content in the nickel-iron foam is X, the iron content in the nickel-iron foam is Y, and X:Y=1:0.43~2.33. When the nickel-iron content ratio is within this range, the catalyst can exhibit excellent OER activity and stability in alkaline electrolyzed water at industrial-grade current density.

[0028] Preferably, X:Y = 1:0.82-1.22. When the nickel-iron content ratio is within this range, the catalyst can exhibit excellent OER activity and stability in alkaline electrolyzed water at industrial-grade current density.

[0029] Specifically, in step S1, the nickel salt is at least one of nickel sulfate, nickel nitrate, nickel chloride, nickel acetate, and nickel sulfite.

[0030] Specifically, in step S1, the iron salt is at least one of ferric sulfate, ferrous sulfate, ferric nitrate, ferric chloride and ferrous chloride.

[0031] Specifically, in step S1, the solvent used to prepare the precursor solution is at least one of deionized water, methanol, ethanol, and ethylene glycol.

[0032] Specifically, in step S1, the concentration of the nickel salt in the precursor solution is 0.01-5.0 mol / L, and the concentration of the iron salt in the precursor solution is 0.01-5.0 mol / L.

[0033] Preferably, the concentration of nickel salt in the precursor solution is 0.5-1.5 mol / L, and the concentration of iron salt in the precursor solution is 0.5-1.5 mol / L. When the concentrations of nickel salt and iron salt in the precursor solution are within this range, the catalyst can exhibit excellent OER activity and stability in alkaline electrolyzed water at industrial-grade current density.

[0034] Specifically, in step S2, the nickel-iron foam is immersed in the precursor solution for 0.2 to 2 hours.

[0035] Specifically, in step S3, the heat treatment temperature is 2500-3000° C., and the heat treatment time is 10-60 seconds. When the heat treatment temperature and time are within this range, the catalyst can exhibit excellent OER activity and stability in alkaline electrolyzed water at industrial-grade current density.

[0036] The second aspect of the present invention provides a catalyst prepared using any one of the above-mentioned methods for preparing a NiFe / INF catalyst.

[0037] The third aspect of the present invention provides an application of a catalyst prepared by any one of the above-mentioned methods for preparing a NiFe / INF catalyst in the field of oxygen evolution reaction by electrolysis of water. Example 1

[0038] This embodiment provides a method for preparing a NiFe / INF catalyst, comprising the following steps: S1. preparing a precursor solution, wherein the precursor solution comprises a nickel salt and an iron salt; S2, soaking the nickel iron foam in the precursor solution; S3. Heat treatment to obtain NiFe / INF catalyst.

[0039] Specifically, in step S2, the nickel content in the nickel-iron foam is X, the iron content in the nickel-iron foam is Y, and X:Y=1:1.

[0040] Specifically, in step S1, the nickel salt is nickel sulfate, and the iron salt is iron sulfate.

[0041] Specifically, in step S1, the solvent used to prepare the precursor solution is deionized water.

[0042] Specifically, in step S1, the concentration of the nickel salt in the precursor solution is 1.0 mol / L, and the concentration of the iron salt in the precursor solution is 1.0 mol / L.

[0043] Specifically, step S1 is as follows: 0.1 mol of nickel sulfate and 0.1 mol of iron sulfate are added into 100 mL of deionized water and ultrasonicated for 30 minutes.

[0044] Specifically, in step S2, the nickel-iron foam is immersed in the precursor solution for 0.5 h.

[0045] Specifically, in step S3, the nickel-iron foam is placed in a pulse electric flash reactor for heat treatment, the heat treatment temperature is 3000° C., and the heat treatment time is 10 s. Example 2

[0046] In this embodiment, different from the embodiment 1, In step S2, the nickel content in the nickel-iron foam is X, the iron content in the nickel-iron foam is Y, and X:Y=1:0.82.

[0047] Specifically, in step S1, the nickel salt is nickel chloride, and the iron salt is ferric chloride.

[0048] Specifically, in step S1, the solvent used to prepare the precursor solution containing nickel salt and iron salt is methanol.

[0049] Specifically, in step S1, the concentration of nickel salt in the precursor solution is 0.5 mol / L, and the concentration of iron salt in the precursor solution is 0.5 mol / L.

[0050] Specifically, in step S2, the nickel iron foam is immersed in the precursor solution containing nickel salt and iron salt for 2 hours.

[0051] In step S3, the heat treatment temperature is 2500° C. and the heat treatment time is 60 s. Example 3

[0052] In this embodiment, different from Embodiment 1, in step S1, the solvents used to prepare the precursor solution containing nickel salt and iron salt are ethanol and ethylene glycol.

[0053] Specifically, in step S1, the nickel salt is nickel nitrate.

[0054] Specifically, in step S1, the iron salt is ferric nitrate.

[0055] Specifically, in step S1, the concentration of nickel salt in the precursor solution is 1.5 mol / L, and the concentration of iron salt in the precursor solution is 1.5 mol / L.

[0056] In step S2, the nickel content in the nickel-iron foam is X, the iron content in the nickel-iron foam is Y, and X:Y=1:1.22.

[0057] Specifically, in step S2, the nickel iron foam is immersed in the precursor solution containing nickel salt and iron salt for 0.2 h.

[0058] In step S3, the heat treatment temperature is 2800° C. and the heat treatment time is 30 s. Comparative Example 1

[0059] In this comparative example, different from Example 1, in step S1, the precursor solution only contains nickel salt, and the nickel salt is nickel sulfate solution. Comparative Example 2

[0060] In this comparative example, different from Example 1, in step S1, the precursor solution only contains iron salt, and the iron salt is ferric sulfate solution. Performance Testing

[0061] 1. The NiFe / INF catalyst prepared in Example 1 was analyzed by scanning electron microscope (SEM). Figure 1 .

[0062] like Figure 1 As shown, the morphology of the NiFe / INF catalyst is composed of undulating NiFe sheets, which is conducive to better penetration of the electrolyte into the electrode, improving the conductivity and high-strength stability.

[0063] 2. X-ray diffraction (XRD) analysis was performed on the NiFe / INF catalyst prepared in Example 1. The results are shown in Figure 2 .

[0064] like Figure 2 As shown, the NiFe / INF catalyst has a diffraction peak at 51.9˚, which matches the (012) crystal plane of Ni(OH)2; there are two diffraction peaks at 44.6˚ and 76.3˚, which match the (260) and (228) crystal planes of Fe2O3. The results show that Ni(OH)2 and Fe2O3 exist in the NiFe / INF catalyst, and the strong interaction between Ni(OH)2 and Fe2O3 helps to regulate the electronic structure of the catalyst, synergistically enhance the conductivity of the catalyst, promote charge transfer and accelerate the reaction rate, thereby improving the OER catalytic performance of the catalyst.

[0065] 3. The traditional three-electrode system was selected to measure the oxygen evolution reaction (OER) performance of the electrocatalysts prepared in Examples 1 to 3 and Comparative Examples 1 to 2. 1.0 M KOH solution was used as the electrolyte, the electrocatalysts prepared in Examples 1 to 3 and Comparative Examples 1 to 2 were used as the working electrode, the carbon rod electrode was used as the counter electrode, and the Hg / HgO electrode was used as the reference electrode. The electrochemical performance of the material was measured by linear voltammetry (LSV). The results are shown in Figure 3and Table 1, Figure 3 is the electrochemical performance diagram (LSV) of the oxygen evolution reaction; and the stability of the electrocatalysts prepared in Examples 1 to 3 and Comparative Examples 1 to 2 was tested by chronoamperometry. The results are shown in Figure 4 .

[0066] Table 1 Catalysts of Examples 1-3 and Comparative Examples 1-2 at 500 mA cm -2 and 1000 mA cm -2 Required OER overpotential at current density

[0067] like Figure 3 As shown in Table 1, at 500 mA cm -2 and 1000 mA cm -2 At the current density of 500 mA cm, the OER overpotential required for the NiFe / INF catalytic material prepared in Example 1 is only 183 mV and 197 mV, respectively. -2 and 1000 mA cm -2 The required overpotentials at the current density of 335 mV and 417 mV are respectively required. The Fe / INF electrode obtained in Comparative Example 2 has a current density of 500 mA cm -2 and 1000 mA cm -2 The required overpotentials are 285 mV and 333 mV at current densities of .

[0068] like Figure 4 As shown, the NiFe / INF catalyst can operate stably for more than 800 hours and has good oxygen evolution reaction stability.

[0069] The catalysts prepared in Comparative Examples 1 and 2 were -2 The stable operation of current density does not exceed 50h. The catalysts prepared in Comparative Examples 1 and 2 show poor stability compared with Example 1.

[0070] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. A method for preparing a NiFe / INF catalyst, characterized in that: The preparation method of the NiFe / INF catalyst comprises the following steps: S1. preparing a precursor solution, wherein the precursor solution comprises a nickel salt and an iron salt; S2, soaking the nickel iron foam in the precursor solution; S3. Heat treatment to obtain NiFe / INF catalyst.

2. The method for preparing a NiFe / INF catalyst according to claim 1, characterized in that: In step S2, the nickel content in the nickel-iron foam is X, the iron content in the nickel-iron foam is Y, and X:Y=1:0.43~2.

33.

3. The method for preparing a NiFe / INF catalyst according to claim 1, characterized in that: In step S1, the nickel salt is at least one of nickel sulfate, nickel nitrate, nickel chloride, nickel acetate, and nickel sulfite.

4. The method for preparing a NiFe / INF catalyst according to claim 1, characterized in that: In step S1, the iron salt is at least one of ferric sulfate, ferrous sulfate, ferric nitrate, ferric chloride and ferrous chloride.

5. The method for preparing a NiFe / INF catalyst according to claim 1, characterized in that: In step S1, the solvent used to prepare the precursor solution is at least one of deionized water, methanol, ethanol, and ethylene glycol.

6. The method for preparing a NiFe / INF catalyst according to claim 1, characterized in that: In step S1, the concentration of the nickel salt in the precursor solution is 0.01-5.0 mol / L, and the concentration of the iron salt in the precursor solution is 0.01-5.0 mol / L.

7. The method for preparing a NiFe / INF catalyst according to claim 1, characterized in that: In step S2, the nickel iron foam is immersed in the precursor solution for 0.2 to 2 hours.

8. The method for preparing a NiFe / INF catalyst according to claim 1, characterized in that: In step S3, the heat treatment temperature is 2500-3000°C, and the heat treatment time is 10-60s.

9. A catalyst prepared using the method for preparing a NiFe / INF catalyst according to any one of claims 1 to 8.

10. Use of a catalyst prepared by the method for preparing a NiFe / INF catalyst according to any one of claims 1 to 8 in the field of oxygen evolution reaction by electrolysis of water.

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