Preparation methods and applications of amorphous NiFe bimetallic hydroxide / reduced graphene oxide composite materials

Abstract

This invention relates to a method for preparing and applying an amorphous NiFe bimetallic hydroxide / reduced graphene oxide composite material. First, graphene oxide is dispersed in ethylene glycol. Then, ferric chloride and nickel acetate are added to the dispersion, and after stirring, sodium acetate is added to obtain a mixture. The mixture is then placed in a hydrothermal reactor and subjected to a hydrothermal reaction at 190°C. The product is centrifuged and washed, and then freeze-dried to obtain the amorphous NiFe bimetallic hydroxide / reduced graphene oxide composite material. The preparation method of this invention is simple and the process is easy to control. By introducing highly conductive reduced graphene oxide, the conductivity of the material is increased. Furthermore, by self-assembling and growing an amorphous active catalyst on the surface of the reduced graphene oxide, its structural stability is improved, thus solving the problems of poor conductivity, poor structural and chemical stability of amorphous catalysts.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, specifically a method for preparing and applying an amorphous NiFe bimetallic hydroxide / reduced graphene oxide composite material. Background Technology

[0002] Hydrogen, with its high energy density and zero carbon emissions, has gradually attracted widespread attention. Among various hydrogen production methods, water electrolysis is considered the most promising. Water electrolysis involves two reactions: the cathode hydrogen evolution reaction and the anodic oxygen evolution reaction. The anodic oxygen evolution reaction involves the transfer of four electrons, resulting in high energy consumption and slow kinetics, which limits the improvement of hydrogen production efficiency. Commercially available oxygen evolution catalysts for water electrolysis are generally precious metal catalysts, which are expensive and have poor stability. Therefore, the development and design of inexpensive non-precious metal catalysts is essential.

[0003] 3d transition metal compounds have attracted considerable attention due to their relatively superior basic oxygen evolution characteristics. Among them, NiFe hydroxide exhibits relatively high catalytic activity and stability. Furthermore, studies have shown that amorphous catalysts, rich in defects and coordinated unsaturated atoms, possess greater structural variability, facilitating electrolyte diffusion into the material and thus exhibiting higher catalytic activity than catalysts with the same composition and crystalline phase. However, the poor electrical conductivity, structural and chemical stability of amorphous catalysts limit their performance improvement. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a method for preparing and applying an amorphous NiFe bimetallic hydroxide / reduced graphene oxide composite material. By introducing highly conductive reduced graphene oxide to increase the conductivity of the material, and by confining the growth of an amorphous active catalyst on the surface of graphene oxide to improve its structural stability, the problem of poor conductivity, poor structural and chemical stability of amorphous catalysts is solved.

[0005] This invention is specifically achieved through the following technical solution: a method for preparing an amorphous NiFe bimetallic hydroxide / reduced graphene oxide composite material according to this invention includes the following steps:

[0006] (1) Add a certain amount of graphene oxide powder to a certain amount of ethylene glycol solvent, stir and sonicate until the graphene oxide is completely dispersed.

[0007] (2) Add a certain mass of FeCl3·6H2O and Ni(CH3COO)2·4H2O to the dispersion obtained in step (1), stir for 2 hours, add a certain amount of CH3COONa·3H2O, and continue stirring until completely dissolved to obtain a mixture.

[0008] (3) Transfer the prepared mixture in step (2) into the polytetrafluoroethylene inner liner of the hydrothermal reactor, put it into the stainless steel shell, seal it well, and then place it in a constant temperature oven at 190°C for 1 hour.

[0009] (4) After the temperature of the outer shell of the hydrothermal reactor drops to room temperature, remove the polytetrafluoroethylene inner liner, centrifuge the black product in the inner liner, discard the supernatant, add anhydrous ethanol to the precipitate obtained after centrifugation, shake to disperse evenly, and centrifuge again; after centrifugation, discard the supernatant, add deionized water to the precipitate obtained, shake to disperse evenly, and centrifuge again, discard the supernatant after centrifugation; repeat this process of alternating centrifugation and washing with ethanol and deionized water twice each, collect the precipitate after centrifugation, freeze-dry it to obtain the amorphous NiFe bimetallic hydroxide / reduced graphene oxide electrolysis oxygen evolution catalyst.

[0010] Furthermore, in the preparation method, the ratio of the total number of moles of Ni and Fe to the number of moles of graphene oxide is 1:(2-6).

[0011] Furthermore, in the preparation method, the mass of graphene oxide powder added in step (1) is 36mg-108mg, and the mixture is first ultrasonically treated for 5min and then stirred for 1 hour.

[0012] Further, in the preparation method, step (2) involves adding 45 mg FeCl3·6H2O and 70 mg Ni(CH3COO)2·4H2O, stirring for 2 hours, and then adding 350 mg CH3COONa·3H2O.

[0013] Furthermore, in the preparation method, step (4) involves a centrifugation rate of 6000 rpm and a centrifugation time of 8-10 min.

[0014] This invention also provides an application of the obtained amorphous NiFe bimetallic hydroxide / reduced graphene oxide composite material in catalytic water electrolysis for oxygen evolution. The prepared composite material is used to fabricate a working electrode for catalytic water electrolysis for oxygen evolution. Specifically, 10 mg of the amorphous NiFe bimetallic hydroxide / reduced graphene oxide composite material is weighed and added to a mixture of 0.5 ml of anhydrous ethanol and deionized water (volume ratio 1:1). The mixture is ultrasonically dispersed for 0.5 hours, then 30 μl of 5 wt% Nafion solution is added, and ultrasonication continues for another 0.5 hours to obtain a catalyst dispersion slurry. 37.5 μl of this slurry is then uniformly drop-coated onto a hydrophilic carbon cloth, with a coating area of ​​1 × 1 cm. 2 After drying naturally at room temperature, the working electrode is obtained.

[0015] Testing showed that the prepared amorphous NiFe bimetallic hydroxide / reduced graphene oxide composite material, when used for catalytic water electrolysis and oxygen evolution, exhibited good performance at 10 mA cm⁻¹.-2 At this current density, only a potential of 232.7 mV is required for driving, and the Tafel slope is 57.9 mVdec. -1 .

[0016] Compared with existing technologies, this invention has significant advantages and beneficial effects. Through the above technical solution, the preparation method and application of the amorphous NiFe bimetallic hydroxide / reduced graphene oxide composite material of this invention achieve considerable technological advancement and practicality, and have broad application value. It possesses at least the following advantages:

[0017] (1) The amorphous NiFe bimetallic hydroxide / reduced graphene oxide composite catalyst provided by this invention only requires a hydrothermal reactor, a constant temperature oven, and a freeze dryer during preparation. The preparation conditions are simple, the energy consumption is relatively low, the raw materials are inexpensive, the reaction process is easy to control, and the catalytic repeatability is good. Reduced graphene oxide (rGO) serves as the support, and the active catalyst NiFe hydroxide is small in size and uniformly dispersed on the reduced graphene oxide, resulting in high catalyst stability.

[0018] (2) In this invention, sodium acetate is selected as the alkali source to provide OH- for the formation of NiFe hydroxide. - The ethylene glycol used serves not only as a solvent but also as a stabilizer. Ethylene glycol restricts particle growth, slowing down the growth rate of NiFe hydroxide particles. Compared to products prepared with water, NiFe hydroxide particles are smaller, which is more conducive to the catalytic reaction. Simultaneously, the negatively charged functional groups and defect sites on the surface of the graphene oxide support can adsorb Ni... 2+ and Fe 3+ The cations become nucleation sites for the growth of NiFe hydroxide, increasing its structural stability.

[0019] (3) TEM images of the materials show that the size of the amorphous NiFe bimetallic hydroxide in the prepared composite catalyst is less than 100 nm. By comparing the XPS spectra of pure NiFe hydroxide and NiFe hydroxide / rGO composite material, it can be found that the Ni 2p and Fe 2p peaks of the composite catalyst shift when graphene is present, indicating that there is an interaction between NiFe hydroxide and reduced graphene oxide (rGO), that is, NiFe hydroxide is anchored-epitaxically grown on rGO.

[0020] (4) The present invention reacts at 190°C for 1 hour. The relatively high reaction temperature and short reaction time result in rapid material growth, generating a large number of defects and leading to a very low degree of material crystallinity, such as... Figure 3 The HRTEM spectrum shows that the material does not exhibit obvious lattice fringes, and the SAED spectrum in the inset shows that the material is amorphous, indicating that amorphous agents have higher catalytic activity.

[0021] (5) The material prepared by this invention is an amorphous active catalyst with high catalytic activity (10 mA cm⁻¹). -2 At this current density, only a potential of 232.7 mV is required for driving, and the Tafel slope is 57.9 mV dec. -1 It can stably evolve oxygen for 100 hours in 1.0M KOH electrolyte.

[0022] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described in detail below with reference to the accompanying drawings. Attached Figure Description

[0023] Figure 1 This is the XRD diffraction pattern of the 4GNF catalyst obtained in Example 1;

[0024] Figure 2 This is a TEM image of the 4GNF catalyst obtained in Example 1;

[0025] Figure 3 These are the HRTEM and selected area electron diffraction patterns of the 4GNF catalyst obtained in Example 1;

[0026] Figure 4 This is the Raman spectrum of the 4GNF catalyst obtained in Example 1;

[0027] Figure 5 The images show a comparison of the fine spectra of Ni 2p and Fe 2p in the XPS spectra of the materials obtained in Examples 1 and 4. 5(a) and 5(b) are high-resolution XPS spectra of Ni 2p and Fe 2p in the amorphous NiFe hydroxide / rGO composite material (Example 1); 5(c) and 5(d) are high-resolution XPS spectra of Ni 2p and Fe 2p in the amorphous NiFe hydroxide (Example 4).

[0028] Figure 6 The linear sweep voltammetric curves of oxygen evolution catalysis of the materials obtained in Examples 1-4 include linear sweep voltammetric curves of conductive carbon cloth substrate and simple reduced graphene oxide.

[0029] Figure 7 It is the oxygen evolution catalytic Tafel slope of the materials obtained in Examples 1-4, including the Tafel slope of simple reduction of graphene oxide;

[0030] Figure 8 The graph shows the overpotential and Tafel slope of the materials obtained in Examples 1-4, including the overpotential and Tafel slope of simply reduced graphene oxide.

[0031] Figure 9 The curves are the oxygen evolution catalytic chronopotential stability test curves of the material obtained in Example 1. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] Example 1

[0034] This embodiment provides a method for preparing an amorphous NiFe bimetallic hydroxide / reduced graphene oxide composite catalyst, wherein the molar ratio of NiFe metal atoms to graphene is approximately 1:4, denoted as 4GNF, and includes the following steps:

[0035] 72 mg of graphene oxide powder was added to 35 ml of ethylene glycol, sonicated for 5 minutes, and then stirred at 500 rpm for 1 hour until the graphene oxide was completely dispersed into a colloid. 45 mg of FeCl3·6H2O and 70 mg of Ni(CH3COO)2·4H2O were added to the dispersion, and the mixture was stirred for 2 hours. Then, 350 mg of CH3COONa·3H2O (2.5 mmol) was added, and the mixture was stirred until the salt was completely dissolved. The prepared solution was poured into a 100 ml PTFE hydrothermal reactor inner liner. The inner liner was placed inside a stainless steel outer shell, tightened, and placed in a constant temperature oven at 190°C for 1 hour. After the outer shell of the hydrothermal reactor cooled to room temperature, the PTFE inner liner was removed. The black product in the inner liner was poured into two 50 ml centrifuge tubes and centrifuged at 6000 rpm for 8 minutes. The supernatant was discarded. Anhydrous ethanol was added to the precipitate obtained after centrifugation, and the mixture was shaken to disperse evenly. The mixture was then centrifuged at 6000 rpm for 8 minutes. After centrifugation, the supernatant was discarded. Deionized water was added to the precipitate, and the mixture was shaken to disperse evenly. The mixture was then centrifuged at 6000 rpm for 8 minutes. The supernatant was discarded after centrifugation. This process of alternating centrifugation with ethanol and deionized water was repeated twice. After centrifugation, the precipitate was collected and freeze-dried for 24 hours.

[0036] Figure 1 This is the XRD diffraction pattern of the 4GNF composite catalyst prepared in this embodiment. As can be seen from the figure, the 4GNF composite catalyst has poor crystallinity and no sharp diffraction peaks appear.

[0037] Figure 2This is a TEM image of the 4GNF composite catalyst prepared in this embodiment. As can be seen from the image, the size of the NiFe hydroxide in the composite catalyst is less than 100 nanometers.

[0038] Figure 3 These are the HRTEM and selected area electron diffraction patterns of the 4GNF composite catalyst prepared in this embodiment. As can be seen from the figures, the prepared 4GNF composite catalyst does not show obvious lattice fringes. The SAED pattern in the inset shows that the material is amorphous, and amorphous agents have higher catalytic activity.

[0039] Figure 4 This is the Raman spectrum of the 4GNF composite catalyst prepared in this embodiment. As can be seen from the figure, at 1346 cm⁻¹... -1 and 1590cm -1 Two characteristic peaks of graphene, the D peak and the G peak, appeared at the locations.

[0040] Example 2

[0041] In this embodiment, the molar ratio of NiFe metal atoms to graphene is approximately 1:2, denoted as 2GNF, and includes the following steps:

[0042] Add 36 mg of graphene oxide powder to 35 ml of ethylene glycol, sonicate for 5 minutes, and then stir at 500 rpm for 1 hour until the graphene oxide is completely dispersed into a colloid. Add 45 mg of FeCl3·6H2O and 70 mg of Ni(CH3COO)2·4H2O to the dispersion and stir for 2 hours. Then add 350 mg of CH3COONa·3H2O (2.5 mmol) and stir until the salt is completely dissolved. Pour the prepared solution into a 100 ml PTFE hydrothermal reactor inner liner, place the inner liner into a stainless steel outer shell, tighten, and place in a constant temperature oven at 190°C for 1 hour. After the hydrothermal reactor outer shell temperature drops to room temperature, remove the PTFE inner liner. Pour equal amounts of the black product from the inner liner into two 50 ml centrifuge tubes, centrifuge at 6000 rpm for 8 minutes, and discard the supernatant. Anhydrous ethanol was added to the precipitate obtained after centrifugation, and the mixture was shaken to disperse evenly. The mixture was then centrifuged at 6000 rpm for 8 minutes. After centrifugation, the supernatant was discarded. Deionized water was added to the precipitate, and the mixture was shaken to disperse evenly. The mixture was then centrifuged at 6000 rpm for 8 minutes. The supernatant was discarded after centrifugation. This process of alternating centrifugation with ethanol and deionized water was repeated twice. After centrifugation, the precipitate was collected and freeze-dried for 24 hours.

[0043] Example 3

[0044] In this embodiment, the molar ratio of NiFe metal atoms to graphene is approximately 1:6, denoted as 6GNF, and includes the following steps:

[0045] 108 mg of graphene oxide powder was added to 35 ml of ethylene glycol, sonicated for 5 minutes, and then stirred at 500 rpm for 1 hour until the graphene oxide was completely dispersed into a colloid. 45 mg of FeCl3·6H2O and 70 mg of Ni(CH3COO)2·4H2O were added to the dispersion, and the mixture was stirred for 2 hours. Then, 350 mg of CH3COONa·3H2O (2.5 mmol) was added, and the mixture was stirred until the salt was completely dissolved. The prepared solution was poured into a 100 ml PTFE hydrothermal reactor inner liner. The inner liner was placed inside a stainless steel outer shell, tightened, and placed in a constant temperature oven at 190°C for 1 hour. After the temperature of the hydrothermal reactor outer shell cooled to room temperature, the PTFE inner liner was removed. The black product in the inner liner was poured into two 50 ml centrifuge tubes and centrifuged at 6000 rpm for 8 minutes. The supernatant was discarded. Anhydrous ethanol was added to the precipitate obtained after centrifugation, and the mixture was shaken to disperse evenly. The mixture was then centrifuged at 6000 rpm for 8 minutes. After centrifugation, the supernatant was discarded. Deionized water was added to the precipitate, and the mixture was shaken to disperse evenly. The mixture was then centrifuged at 6000 rpm for 8 minutes. The supernatant was discarded after centrifugation. This process of alternating centrifugation with ethanol and deionized water was repeated twice. After centrifugation, the precipitate was collected and freeze-dried for 24 hours.

[0046] Example 4

[0047] In this embodiment, without the addition of graphene oxide, amorphous NiFe hydroxide, denoted as NiFe, is prepared, comprising the following steps:

[0048] Add 45 mg of FeCl3·6H2O and 70 mg of Ni(CH3COO)2·4H2O to 35 ml of ethylene glycol and stir for 2 hours. Then add 350 mg of CH3COONa·3H2O (2.5 mmol) and stir until the salt is completely dissolved. Pour the prepared solution into a 100 ml PTFE hydrothermal reactor inner liner, place the inner liner into a stainless steel outer shell, tighten it, and place it in a constant temperature oven at 190°C for 1 hour. After the temperature of the hydrothermal reactor outer shell has cooled to room temperature, remove the PTFE inner liner. Pour equal amounts of the black product from the inner liner into two 50 ml centrifuge tubes, centrifuge at 6000 rpm for 8 minutes, and discard the supernatant. Anhydrous ethanol was added to the precipitate obtained after centrifugation, and the mixture was shaken to disperse evenly. The mixture was then centrifuged at 6000 rpm for 8 minutes. After centrifugation, the supernatant was discarded. Deionized water was added to the precipitate, and the mixture was shaken to disperse evenly. The mixture was then centrifuged at 6000 rpm for 8 minutes. The supernatant was discarded after centrifugation. This process of alternating centrifugation with ethanol and deionized water was repeated twice. After centrifugation, the precipitate was collected and freeze-dried for 24 hours.

[0049] Preparation of test electrodes:

[0050] 10 mg of the amorphous NiFe bimetallic hydroxide / reduced graphene oxide composite catalyst prepared in Example 1 was weighed and added to 0.5 ml of a mixture of anhydrous ethanol and deionized water (volume ratio 1:1). The mixture was ultrasonically dispersed for 0.5 hours, followed by the addition of 30 μl of Nafion solution (5 wt%). Ultrasonic dispersion was continued for another 0.5 hours to obtain the catalyst slurry. 37.5 μl of the slurry was uniformly drop-coated onto a hydrophilic carbon cloth, covering an area of ​​1 × 1 cm². 2 After natural drying at room temperature, an amorphous NiFe hydroxide / rGO test electrode was obtained, and an oxygen evolution test was performed on the water electrolysis electrode.

[0051] Following the same method, 10 mg of the amorphous NiFe hydroxide prepared in Example 4 was added to 0.5 ml of a mixture of anhydrous ethanol and deionized water (volume ratio 1:1), and ultrasonically dispersed for 0.5 hours. Then, 30 μl of Nafion solution (5 wt%) was added, and ultrasonication was continued for another 0.5 hours to obtain a catalyst dispersion slurry. 37.5 μl of the slurry was uniformly drop-coated onto a hydrophilic carbon cloth, with a coating area of ​​1 × 1 cm. 2 After natural drying at room temperature, a NiFe hydroxide test electrode was obtained, and an oxygen evolution test was performed on the water electrolysis.

[0052] The prepared amorphous NiFe hydroxide / rGO test electrode was used as the working electrode for the water electrolysis oxygen evolution test, Ag / AgCl was used as the reference electrode, a graphite rod was used as the counter electrode, and 1M KOH solution was used as the electrolyte. After passing high-purity O2 through for 30 min, the three electrodes were connected to the corresponding electrodes of the electrochemical workstation for electrochemical testing.

[0053] The same method was used to perform electrochemical tests on the NiFe hydroxide test electrode.

[0054] In a three-electrode system, the electrocatalytic activity of the amorphous NiFe hydroxide / rGO composite catalyst and the NiFe hydroxide material was tested. First, the activation test of cyclic voltammetry was performed. After the working electrode was stabilized, the polarization curve was obtained by linear sweep voltammetry.

[0055] Figure 5 (a) and Figure 5(b) is the XPS high-resolution spectrum of Ni 2p and Fe 2p of the amorphous NiFe hydroxide / rGO composite catalyst (Example 1); 5(c) and 5(d) are the XPS high-resolution spectra of Ni 2p and Fe 2p of NiFe hydroxide (Example 4). It can be seen from the figure that the Ni 2p and Fe 2p peaks of the amorphous bimetallic NiFe hydroxide / rGO composite catalyst are shifted relative to the peaks of the pure amorphous NiFe hydroxide, indicating that there is an interfacial charge transport effect between NiFe hydroxide and the reduced graphene oxide support. The main reason is that NiFe hydroxide is anchored-epitaxically grown on rGO.

[0056] Figure 6 The figures show the linear sweep voltammetric curves of the oxygen evolution catalysis of the materials obtained in Examples 1-4, including the linear sweep voltammetric curves of the conductive carbon cloth substrate and the simple reduced graphene oxide (rGO). As can be seen from the figures, the catalysts obtained in Examples 1-4 have better catalytic performance than the simple conductive carbon cloth substrate and the simple rGO. Among them, the amorphous NiFe hydroxide / rGO composite catalyst (Examples 1-3) has better catalytic performance than the simple NiFe hydroxide (Example 4), and the catalyst has the best catalytic performance when the molar ratio of NiFe metal atoms to graphene is about 1:4 (Example 1).

[0057] Figure 7 The figure shows the Tafel slope of the oxygen evolution catalyst obtained in Examples 1-4, including the Tafel slope of the oxygen evolution catalyst of simply reducing graphene oxide (rGO). As can be seen from the figure, when the molar ratio of NiFe metal atoms to graphene is approximately 1:4 (Example 1), the prepared composite catalyst has a lower Tafel slope, indicating that the composite catalyst prepared in Example 1 has a faster catalytic reaction rate.

[0058] To more clearly compare Examples 1-4 and simply reduced graphene oxide materials at 10 mA / cm² -2 The overpotential and Tafel slope at time, for Figure 6 and Figure 7 The test results were statistically analyzed, such as... Figure 8 As shown: When the molar ratio of NiFe metal atoms to graphene is approximately 1:4 (Example 1), the prepared composite catalyst exhibits a lower overpotential: 10 mA cm⁻¹. -2 At this current density, only a potential of 232.7 mV is required for driving, and the Tafel slope is 57.9 mV dec. -1 .

[0059] The catalytic stability of the composite catalyst obtained in Example 1 was further tested. Specifically, in a three-electrode system, a chronopotential testing program was selected in an electrochemical workstation, and the reaction current density was set to 10 mA / cm².2 Oxygen evolution tests were performed on the materials. The results are as follows: Figure 9 As shown, the electrode material prepared by the composite catalyst obtained in Example 1 can stably catalyze oxygen evolution for 100 hours with an overpotential increase of only 2%, indicating that the composite catalyst prepared in Example 1 has very good stability.

[0060] The above description is merely an embodiment of the present invention and is not intended to limit the present invention in any way. The present invention can also have other embodiments based on the above structure and function, which will not be listed hereafter. Therefore, any simple modifications, equivalent changes, and alterations made by those skilled in the art to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for preparing an amorphous NiFe bimetallic hydroxide / reduced graphene oxide composite material, characterized in that... Includes the following steps: (1) Add 72 mg of graphene oxide powder to 35 ml of ethylene glycol solvent, sonicate for 5 minutes and stir for 1 hour until the graphene oxide is completely dispersed. (2) Add 45 mg of FeCl3⋅6H2O and 70 mg of Ni(CH3COO)2⋅4H2O to the dispersion obtained in step (1), stir for 2 hours, add 350 mg of CH3COONa⋅3H2O, and continue stirring until completely dissolved to obtain a mixture. (3) Transfer the prepared mixture in step (2) into the polytetrafluoroethylene inner liner of the hydrothermal reactor, put it into the stainless steel shell, seal it well, and then place it in a constant temperature oven at 190°C for 1 hour. (4) After the temperature of the outer shell of the hydrothermal reactor drops to room temperature, remove the polytetrafluoroethylene inner liner, centrifuge the black product in the inner liner, discard the supernatant, add anhydrous ethanol to the precipitate obtained after centrifugation, shake to disperse evenly, and centrifuge again; after centrifugation, discard the supernatant, add deionized water to the precipitate obtained, shake to disperse evenly, and centrifuge again, discard the supernatant after centrifugation; use ethanol and deionized water alternately for centrifugation and washing twice each, after centrifugation, collect the precipitate, freeze dry for 24 hours to obtain the amorphous NiFe bimetallic hydroxide / reduced graphene oxide electrolysis oxygen evolution catalyst.

2. The preparation method of the amorphous NiFe bimetallic hydroxide / reduced graphene oxide composite material according to claim 1, characterized in that... In step (4), the centrifugation rate is 6000 rpm and the centrifugation time is 8-10 min.

3. The preparation method of the amorphous NiFe bimetallic hydroxide / reduced graphene oxide composite material according to claim 1, characterized in that... The prepared amorphous NiFe bimetallic hydroxide / reduced graphene oxide catalyst was used as the working electrode for catalytic water electrolysis and oxygen evolution. Specifically, 10 mg of the amorphous NiFe bimetallic hydroxide / reduced graphene oxide composite material was weighed and added to a mixture of 0.5 ml of anhydrous ethanol and deionized water (volume ratio 1:1). The mixture was ultrasonically dispersed for 0.5 hours, followed by the addition of 30 μl of 5 wt% Nafion solution and another 0.5 hours of ultrasonication to obtain a catalyst dispersion slurry. 37.5 μl of the dispersion slurry was then uniformly drop-coated onto a hydrophilic carbon cloth, with a coating area of ​​1 × 1 cm. 2 After drying naturally at room temperature, the working electrode is obtained.

4. The method for preparing the amorphous NiFe bimetallic hydroxide / reduced graphene oxide composite material according to claim 1 or 3, characterized in that... The prepared amorphous NiFe bimetallic hydroxide / reduced graphene oxide electrolysis oxygen evolution catalyst, when used for catalytic water electrolysis oxygen evolution, exhibits performance at 10 mA cm⁻¹. -2 At a current density of only 232.7 mV, a Tafel slope of 57.9 mV dec is required for driving. -1 .

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