Iron-nickel-molybdenum trimetal-based oxide electrocatalyst and preparation method and application thereof

Abstract

The invention relates to an iron-nickel-molybdenum trimetal-based oxide electrocatalyst and a preparation method and application thereof, and the method comprises the following steps: carrying out ultrasonic treatment on a carrier, and drying to obtain a treated carrier; dissolving a nickel source, an iron source and a molybdenum source in water and mixing to obtain a mixed solution; performing solvothermal reaction on the treated carrier and the mixed solution, and obtaining a crude product after the reaction is completed; and cooling, washing and drying the crude product to obtain the iron-nickel-molybdenum trimetal-based oxide electrocatalyst. Compared with the prior art, the preparation method has the advantages of simple preparation process, fast reaction kinetics and good oxygen evolution reaction activity and stability.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrocatalysts, and relates to a ternary metal-based iron-nickel-molybdenum oxide electrocatalyst, a preparation method thereof, and an application thereof. Background Art

[0002] The problems of energy shortage and air pollution have become urgent concerns for people. Solar and wind power generation can replace traditional fossil fuels, but solar and wind energies have problems such as intermittency, low efficiency, and waste. As one of the most promising alternative energy sources in the 21st century, hydrogen energy is increasingly attracting people's attention in replacing fossil fuels and reducing environmental pollution. Hydrogen production by water electrolysis has broad prospects. The electrolysis of water to produce hydrogen and oxygen is one of the most promising methods for generating clean and sustainable fuels using intermittent renewable energy. As two crucial processes in electrocatalytic water splitting, the oxygen evolution reaction and the hydrogen evolution reaction are affected by complex electron transfer steps, including four-electron and two-electron transfers. These multi-step reactions result in problems such as high reaction overpotential and poor kinetic properties of electrocatalysts. These steps play a crucial role in determining the overall rate of the water electrolysis process. In addition, the scarcity of noble metal resources, small specific surface area, insufficient active sites, and too strong or too weak surface adsorption energy also limit the electrocatalytic activity. Therefore, in order to improve the efficiency of electrocatalytic water splitting, it is necessary to find suitable catalysts to achieve low reaction overpotential, excellent kinetic properties, high current density, etc. to promote large-scale production.

[0003] Patent CN116970975A discloses a preparation method and application of a NiMo-based bimetallic oxide electrocatalyst. The specific preparation steps are as follows: S1. Take nickel foam and perform ultrasonic treatment successively with hydrochloric acid, deionized water, and absolute ethanol, and dry it in a vacuum furnace; S2. Dissolve Ni(NO3)2·6H2O powder and (NH4)6Mo7O 24 ·4H2O powder separately in deionized water, and then mix and stir; S3. Place the mixed solution prepared in S2 and the nickel foam treated in S1 into a container for solvothermal reaction, and take out the crude product after the reaction is completed; S4. Take thioacetamide and dissolve it in ethylene glycol, and then place the crude product obtained in S3 into a container for solvothermal reaction, and take out the crude product after the reaction is completed; S5. Wash and dry the crude product prepared in S4, and perform a calcination reaction in a specific atmosphere. Although the electrocatalyst prepared by the two-step hydrothermal and calcination methods in this patent has achieved good results, the preparation method of this patent is cumbersome and difficult for large-scale production.

[0004] Patent CN108796535A discloses a trimetallic copper-cobalt-molybdenum / nickel foam porous electrode material and its preparation method and application. The method includes: (1) First, use an organic solution and acid to remove the oil stain and oxide layer on the surface of nickel foam; (2) Place the copper, cobalt, and molybdenum salt compound precursors and nickel foam in a autoclave for a sealed reaction, then wash and dry to obtain nickel foam with a hydrothermal synthesis product grown on its surface; (3) Calcinate the nickel foam obtained in step (2) at a high temperature in a hydrogen atmosphere, and then naturally cool to obtain a trimetallic copper-cobalt-molybdenum / nickel foam porous electrolytic water catalyst. However, the stacking structure of this patent results in insufficient active sites and it is difficult to perform long-term electrocatalysis.

[0005] Patent CN113430553A discloses a bifunctional catalytic electrode based on a transition metal heterolayered structure and its preparation method. A layered composite structure material is synthesized by stepwise growth of a transition metal alloy with hydrogen evolution reaction catalytic performance and a transition metal hydroxide with oxygen evolution reaction catalytic performance. Using nickel foam loaded with a transition metal alloy as a carrier, the transition metal hydroxide is controlled to grow in-situ on the surface of the carrier to form an alkaline electrolytic water catalytic electrode with dual catalytic functions. However, the reaction kinetics of this patent is relatively slow, and the overpotential required at a current density of 10 mA·cm -2 is still relatively large. Summary of the Invention

[0006] The purpose of the present invention is to overcome at least one defect of the above-mentioned existing technologies, such as the cumbersome preparation process leading to difficulty in large-scale production, slow reaction kinetics, affecting the improvement of catalyst performance and stability, etc. A trimetallic iron-nickel-molybdenum-based oxide electrocatalyst, its preparation method and application are provided. The present invention has a simple preparation process, fast reaction kinetics, good oxygen evolution reaction activity and stability.

[0007] The purpose of the present invention can be achieved through the following technical solutions:

[0008] One of the technical solutions of the present invention lies in providing a preparation method of a trimetallic iron-nickel-molybdenum-based oxide electrocatalyst, which includes the following steps:

[0009] S1. Ultrasonically treat the carrier and dry it to obtain a treated carrier;

[0010] S2. Dissolve a nickel source, an iron source, and a molybdenum source in water and mix them to obtain a mixed solution;

[0011] S3. Perform a solvothermal reaction on the treated carrier and the mixed solution, and obtain a crude product after the reaction is completed;

[0012] S4. Cool, wash, and dry the crude product to obtain a trimetallic iron-nickel-molybdenum-based oxide electrocatalyst.

[0013] Further, in step S1, the carrier includes nickel foam or carbon cloth;

[0014] In step S2, the nickel source includes nickel chloride (NiCl2) or nickel nitrate (Ni(NO3)2), the iron source includes iron chloride (FeCl3) or iron nitrate (Fe(NO3)3), and the molybdenum source uses sodium molybdate (Na2MoO4).

[0015] Further, the area / mole / volume ratio of the carrier in step S1 to the nickel source, iron source, molybdenum source, and water in step S2 is (2 - 4 cm 2 ):(2 - 3 mmol):(2 - 3 mmol):(4 - 6 mmol):(25 - 40 mL).

[0016] Further, the reagent for ultrasonic treatment in step S1 is selected from one or more of hydrochloric acid, water, and ethanol, and the concentration of hydrochloric acid is 0.5 - 1.5 mol / L.

[0017] Further, the frequency of ultrasonic treatment in step S1 is 80 - 120 kHz, and the time is 20 - 25 min;

[0018] The drying temperature is 65 - 75 °C, and the time is 1 - 3 h.

[0019] Further, the mixing temperature in step S2 is room temperature, and the time is 15 - 25 min.

[0020] Further, the reaction temperature in step S3 is 155 - 165 °C, and the time is 6.5 - 7.5 h.

[0021] Further, the reagent for washing in step S4 is selected from one or more of water and ethanol;

[0022] The drying temperature is 75 - 85 °C, and the time is 13 - 15 h.

[0023] As a preferred technical solution, it is cooled to room temperature in step S4.

[0024] One of the technical solutions of the present invention is to provide an iron-nickel-molybdenum trimetal-based oxide electrocatalyst prepared by the said method.

[0025] One of the technical solutions of the present invention is to provide an application of the said iron-nickel-molybdenum trimetal-based oxide electrocatalyst, and the electrocatalyst is applied to the oxygen evolution reaction (OER) of water electrolysis.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] (1) In the iron-nickel-molybdenum trimetal-based oxide electrocatalyst of the present invention, the electron synergistic effect between multi-metal atoms has a very suitable adsorption energy for hydroxide ions;

[0028] (2) The addition of iron in the present invention can form a flaky sphere structure, which has a large surface area and increases the active sites of the electrocatalyst;

[0029] (3) The nickel-molybdenum-based catalyst of the present invention has good electron transport characteristics and appropriate adsorption energy, which is beneficial to enhancing the oxygen evolution reaction activity. Only a overpotential of 223 mV is required to drive a current density of 10 mA·cm -2 ;

[0030] (4) The present invention has a simple preparation process, fast electrocatalytic reaction kinetics, good oxygen evolution reaction activity and long-term stability. It has better performance than the existing commercial electrocatalysts at a current density of 10 mA·cm -2 and has good application in electrolyzing water as an electrode material in large-scale energy storage. Description of the Drawings

[0031] Figure 1 is a scanning electron microscope (SEM) image of the iron-nickel-molybdenum trimetal-based oxide electrocatalyst in the embodiment of the present invention;

[0032] Figure 2 is an energy dispersive spectroscopy (EDS) image of iron element of the iron-nickel-molybdenum trimetal-based oxide electrocatalyst in the embodiment of the present invention;

[0033] Figure 3 is an EDS image of nickel element of the iron-nickel-molybdenum trimetal-based oxide electrocatalyst in the embodiment of the present invention;

[0034] Figure 4 is an EDS image of molybdenum element of the iron-nickel-molybdenum trimetal-based oxide electrocatalyst in the embodiment of the present invention;

[0035] Figure 5 is an EDS image of oxygen element of the iron-nickel-molybdenum trimetal-based oxide electrocatalyst in the embodiment of the present invention;

[0036] Figure 6 is a linear sweep polarization curve graph of the electrocatalyst in the embodiment of the present invention and the comparative example;

[0037] Figure 7 is a graph of the relationship between the current density and time of the iron-nickel-molybdenum trimetal-based oxide electrocatalyst in the embodiment of the present invention. Detailed Embodiments

[0038] The present invention will be described in detail below with reference to specific embodiments. These embodiments are implemented on the premise of the technical solution of the present invention, and detailed implementation methods and specific operation processes are given. However, the protection scope of the present invention is not limited to the following embodiments.

[0039] Unless otherwise specified, the equipment used in the following examples is a conventional equipment in the art; unless otherwise specified, the reagents used are commercially available products or prepared by conventional methods in the art. Those not described in detail in the following examples can be achieved by conventional experimental means in the art.

[0040] The following raw materials were all purchased from Shanghai Titan Scientific Co., Ltd. All chemicals were of analytical grade and were not further purified.

[0041] Example:

[0042] A ternary iron-nickel-molybdenum-based oxide electrocatalyst and its preparation method are as follows:

[0043] S1. Take nickel foam with an area of 1×3 cm 2 and place it in a beaker. Successively perform ultrasonic treatment at 100 kHz for 22 min with 1 mol / L hydrochloric acid, deionized water, and absolute ethanol, and then put it into a vacuum furnace at 70 °C for drying for 2 h to obtain treated nickel foam.

[0044] S2. Take 2.5 mmol of nickel chloride hexahydrate (NiCl2·6H2O) powder, 2.5 mmol of ferric chloride hexahydrate (FeCl3·6H2O) powder, and 5 mmol of sodium molybdate dihydrate (Na2MoO4·2H2O) powder, respectively add them to 35 mL of deionized water to dissolve and then mix at room temperature, and perform magnetic stirring for 20 min to obtain a mixed solution.

[0045] S3. Perform a solvothermal reaction on the treated nickel foam and the mixed solution in a polytetrafluoroethylene reaction kettle. The reaction temperature is 160 °C and the time is 7 h. After the reaction is completed, a crude product is obtained.

[0046] S4. Cool the crude product to room temperature, wash it with deionized water and absolute ethanol, and dry it in a vacuum drying oven at 80 °C for 14 h to obtain a ternary iron-nickel-molybdenum-based oxide electrocatalyst.

[0047] As Figure 1 shown, it can be seen that the example has a flaky spherical morphology, which increases the surface area and is conducive to increasing the active sites.

[0048] As Figures 2 to 5 shown, it can be seen that the surface of the example contains iron, nickel, molybdenum, and oxygen elements, and it can be judged that the electrocatalyst is successfully prepared.

[0049] Comparative example:

[0050] An electrocatalyst and its preparation method. Take 5 mg of commercial benchmark ruthenium dioxide (RuO2) electrocatalyst, add 25 μL of Nafion, 780 μL of isopropanol, and 295 μL of deionized water, and ultrasonically treat it for 30 min at 60 kHz to obtain the electrocatalyst.

[0051] The electrochemical performance test of the above electrocatalyst is as follows:

[0052] Use a Chenhua CHI 660E electrochemical workstation for testing. The test temperature is room temperature, and the electrolyte is 1 mol / L potassium hydroxide (KOH) solution. Among them, a platinum sheet electrode is selected as the counter electrode, a Hg / HgO electrode is selected as the reference electrode, and the above electrocatalyst is selected as the working electrode. Correct the voltage loss iR compensation caused by the electrolyte solution between the working electrode and the reference electrode by 95%;

[0053] In the voltage window of 1.1 - 1.8 V (vs. RHE), select a reverse scan operation and obtain a linear sweep polarization (LSV) curve at a scan rate of 5 mV / s.

[0054] As Figure 6 shown, it can be seen that at a current density greater than 2 mA·cm -2 , the iron-nickel-molybdenum trimetal-based oxide electrocatalyst of the example has a smaller overpotential compared to the RuO2 electrocatalyst of the comparative example. For example, at 10 mA·cm - 2, the example only requires an overpotential of 223 mV, and the activity is much higher than the 307 mV shown by the comparative example. Therefore, the iron-nickel-molybdenum trimetal-based oxide electrocatalyst of the example has more excellent kinetic characteristics than the commercial electrocatalyst at high current densities.

[0055] As Figure 7 shown, it can be seen that the example basically maintains a current density of 10 mA·cm -2 for nearly 20 h, and the iron-nickel-molybdenum trimetal-based oxide electrocatalyst of the example shows good electrochemical stability.

[0056] The present invention provides a preparation method of an iron-nickel-molybdenum trimetal-based oxide electrocatalyst. The iron-nickel-molybdenum trimetal-based oxide electrocatalyst is synthesized by one-step solvothermal method, with much higher activity than commercial catalysts, improved double-layer capacitance, more active sites, and faster reaction kinetics of the oxygen evolution reaction (OER). These advantages make the iron-nickel-molybdenum trimetal-based oxide electrocatalyst have a very broad application prospect and application potential as an electrode material for electrolyzing water in large-scale energy storage.

[0057] The above description of the embodiments is provided to enable those of ordinary skill in the art to understand and use the invention. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative efforts. Therefore, the present invention is not limited to the above embodiments, and the improvements and modifications made by those skilled in the art without departing from the scope of the present invention according to the disclosure of the present invention should be within the protection scope of the present invention.

Claims

1. A preparation method of an iron-nickel-molybdenum trimetal-based oxide electrocatalyst, characterized in that, The method comprises the following steps: S1. Ultrasonically treating the carrier and drying it to obtain a treated carrier; S2. Dissolving a nickel source, an iron source and a molybdenum source in water and mixing them to obtain a mixed solution; S3. Subjecting the treated carrier and the mixed solution to a solvothermal reaction, and obtaining a crude product after the reaction is completed; S4. Cooling, washing and drying the crude product to obtain an iron-nickel-molybdenum trimetal-based oxide electrocatalyst.

2. The preparation method of an iron-nickel-molybdenum trimetal-based oxide electrocatalyst according to claim 1, wherein In step S1, the carrier includes nickel foam or carbon cloth; In step S2, the nickel source includes nickel chloride or nickel nitrate, the iron source includes iron chloride or iron nitrate, and the molybdenum source is sodium molybdate.

3. The preparation method of a nickel-iron-molybdenum trimetal-based oxide electrocatalyst according to claim 1, wherein, In step S1, the area / mole / volume ratio of the carrier to the nickel source, iron source, molybdenum source, and water in step S2 is (2 - 4 cm 2 ):(2 - 3 mmol):(2 - 3 mmol):(4 - 6 mmol):(25 - 40 mL).

4. The preparation method of a nickel-iron-molybdenum trimetal-based oxide electrocatalyst according to claim 1, characterized in that, In step S1, the reagent for ultrasonic treatment is selected from one or more of hydrochloric acid, water, and ethanol, and the concentration of hydrochloric acid is 0.5 - 1.5 mol / L.

5. The preparation method of a ternary iron-nickel-molybdenum-based oxide electrocatalyst according to claim 1, characterized in that, In step S1, the ultrasonic frequency is 80 - 120 kHz and the time is 20 - 25 min; The drying temperature is 65 - 75 °C and the time is 1 - 3 h.

6. The preparation method of an iron-nickel-molybdenum trimetal-based oxide electrocatalyst according to claim 1, characterized in that, In step S2, the mixing temperature is room temperature and the time is 15 - 25 min.

7. The preparation method of a ternary iron-nickel-molybdenum-based oxide electrocatalyst according to claim 1, characterized in that, In step S3, the reaction temperature is 155 - 165 °C and the time is 6.5 - 7.5 h.

8. The preparation method of a ternary iron-nickel-molybdenum-based oxide electrocatalyst according to claim 1, wherein, In step S4, the washing reagent is selected from one or more of water and ethanol; The drying temperature is 75 - 85 °C and the time is 13 - 15 h.

9. An iron-nickel-molybdenum trimetal-based oxide electrocatalyst prepared by the method according to any one of claims 1 to 8.

10. Use of the iron-nickel-molybdenum trimetal-based oxide electrocatalyst as described in claim 9, characterized in that, The electrocatalyst is applied to the oxygen evolution reaction of electrolyzing water.

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