All-transition-metal-based oxygen evolution electrocatalyst and preparation method and application thereof

Abstract

The application belongs to the technical field of electrocatalysis, and discloses a full-transition-metal-based oxygen evolution electrocatalyst and a preparation method and application thereof; the preparation method comprises the following steps: placing NiPS3 nanosheets into a mixed aqueous solution of a cobalt metal salt and an iron metal salt, uniformly mixing, and then performing centrifugal treatment to obtain a precipitate; under stirring conditions, dispersing the obtained precipitate in water to obtain a mixed aqueous solution of the precipitate; under a temperature condition below room temperature, adding a reducing agent containing element B into the mixed aqueous solution of the precipitate, performing reaction under stirring conditions, and performing centrifugal treatment, washing and drying to prepare a CoFeB / NiPS3 heterostructure. The full-transition-metal-based oxygen evolution catalyst prepared by the application has the advantage of low cost compared with a noble metal catalyst, and can match the noble metal catalyst in terms of catalytic performance and stability.

Description

Technical Field

[0001] This invention belongs to the field of electrocatalysis technology, and specifically relates to a fully transition metal-based oxygen evolution electrocatalyst, its preparation method, and its application. Background Technology

[0002] Environmental pollution and energy issues have become two of the most serious problems restricting the development of human society. Developing green and clean energy is of paramount importance; among them, hydrogen energy is known as the most promising clean energy source of the 21st century due to its advantages such as high calorific value, being green and pollution-free, and having wide availability.

[0003] Electrolysis of water to produce hydrogen (explained as 2H₂O → O₂ + 2H₂) has advantages such as high product purity and simple process, making it the most efficient method for hydrogen production. However, the efficiency of water electrolysis is largely limited by the slow oxygen evolution reaction (OER) at the anode. Currently, the most advanced OER catalysts are precious metals such as IrO₂ / RuO₂, whose high price limits large-scale application. Therefore, developing inexpensive and efficient non-precious metal OER catalysts has become an important problem to be solved in green hydrogen production.

[0004] In recent years, MPS3 (M = Ni, Co, Fe) has emerged as a novel two-dimensional (2D) material, bringing new opportunities to the field of electrocatalytic decomposition. Compared with other materials, it exhibits high anisotropy. Taking NiPS3 as an example, it can form P and S-doped NiOOH substances in situ in a "one-step" process during OER, and is considered to be the true active material for OER; however, bulk NiPS3 has low intrinsic activity.

[0005] In existing research, NiPS3 has been improved by forming heterostructures through composites with transition metal-based phosphides, sulfides, and redox graphene. However, the preparation process of the above composite materials is complex, and the catalytic performance of the prepared composite materials is still far from that of industrial applications. Summary of the Invention

[0006] The purpose of this invention is to provide a fully transition metal-based oxygen evolution electrocatalyst, its preparation method, and its applications, in order to solve one or more of the aforementioned technical problems. The technical solution provided by this invention has the advantages of a simple preparation process, high yield, and low time cost; the prepared fully transition metal-based oxygen evolution catalyst has the advantage of low cost compared to noble metal catalysts, and its catalytic performance and stability are comparable to those of noble metal catalysts.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] In a first aspect, this invention provides a method for preparing an all-transition metal-based oxygen evolution electrocatalyst, comprising:

[0009] NiPS3 nanosheets were placed in a mixed aqueous solution of cobalt metal salt and iron metal salt, mixed evenly, and then centrifuged to obtain a precipitate.

[0010] Under stirring conditions, the obtained precipitate is dispersed in water to obtain a mixed aqueous solution of the precipitate;

[0011] A reducing agent containing element B was added to the mixed aqueous solution of the precipitate at a temperature below room temperature. The reaction was carried out under stirring, followed by centrifugation, washing, and drying to prepare the CoFeB / NiPS3 heterostructure.

[0012] A further improvement to the preparation method of the present invention is that,

[0013] In the mixed aqueous solution of cobalt metal salt and iron metal salt, the molar ratio of cobalt metal salt to iron metal salt is (0.5-4):1.

[0014] A further improvement to the preparation method of the present invention is that,

[0015] The solvent used in the mixed aqueous solution of the cobalt metal salt and the iron metal salt, as well as the mixed aqueous solution of the precipitate, is nitrogen-saturated deionized water.

[0016] A further improvement to the preparation method of the present invention is that,

[0017] The cobalt metal salt is one or more of cobalt nitrate, cobalt acetate, cobalt chloride, and cobalt sulfate;

[0018] The iron metal salt is one or more of ferrous sulfate and ferrous chloride.

[0019] A further improvement to the preparation method of the present invention is that,

[0020] The reducing agent containing element B is sodium borohydride or potassium borohydride.

[0021] A further improvement to the preparation method of the present invention is that the step of adding a reducing agent containing element B to the mixed aqueous solution of the precipitate is as follows:

[0022] An aqueous solution containing a reducing agent of element B is added to the mixed aqueous solution of the precipitate at a preset flow rate to avoid the aggregation of the reducing agent;

[0023] The solvent in the aqueous solution of the reducing agent containing element B is nitrogen-saturated deionized water.

[0024] A further improvement to the preparation method of the present invention is that the temperature condition below room temperature is specifically as follows:

[0025] Temperature conditions of 8℃~15℃.

[0026] A further improvement to the preparation method of the present invention is that the preparation method of the NiPS3 nanosheets includes:

[0027] The anode with platinum wire and the cathode with NiPS3 bulk were inserted into an electrolytic cell, and an electrochemical cathode stripping was performed by applying a voltage of 5V to 10V. After stripping, the cathode was subjected to ultrasonication, centrifugation and washing to obtain NiPS3 nanosheets.

[0028] The solvent in the electrolytic cell is N,N-dimethylformamide, and the solute is tetrahexylammonium bromide.

[0029] In a second aspect, the present invention provides a fully transition metal-based oxygen evolution electrocatalyst prepared by the preparation method described in any one of the first aspects of the present invention.

[0030] The fully transition metal-based oxygen evolution electrocatalyst has a CoFeB / NiPS3 heterostructure.

[0031] The transition metals in the CoFeB / NiPS3 heterostructure are cobalt, iron, and nickel, and the heterostructure exhibits a 2D / 2D vertical growth microstructure.

[0032] In a third aspect of the present invention, an application of the fully transition metal-based oxygen evolution electrocatalyst described in the second aspect of the present invention is provided, wherein the fully transition metal-based oxygen evolution electrocatalyst is used as an anodic oxygen evolution reaction catalyst in the process of water electrolysis.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] The method for preparing the all-transition metal-based electrocatalyst provided by this invention involves transferring NiPS3 nanosheets into a mixed aqueous solution containing cobalt and iron metal salts, then transferring the precipitate obtained by centrifugation to deionized water, and adding a reducing agent to prepare an oxygen evolution electrocatalyst with excellent oxygen evolution performance and good stability. Explainingly, current methods for preparing NiPS3-based electrocatalysts include hydrothermal methods and oil-phase methods. These methods typically require extremely high reaction temperatures, harsh reaction conditions, low yields, and complex preparation processes. In contrast, the preparation method provided by this invention has a simple reaction process, with the key step being the reduction step. The reaction temperature is below room temperature, resulting in high yields. Furthermore, the time cost required for the reaction is low, and it does not involve the heating and cooling processes of traditional reactions. Therefore, the preparation method provided by this invention has the advantages of a simple preparation process, high yield, and low time cost.

[0035] The fully transition metal-based oxygen evolution electrocatalyst prepared in this invention exhibits superior oxygen evolution performance and stability compared to currently commercially available ruthenium dioxide, while also possessing lower cost, making it promising for industrial application. Further specifically, the fully transition metal-based electrocatalyst prepared in this invention achieves oxygen evolution performance at 50 mA cm⁻¹.-2 At a current density of 20 mA / cm², its overpotential is 285 mV, which is significantly better than that of the commercial catalyst ruthenium dioxide at 20 mA / cm². -2 The overpotential at the current density is 400mV. In addition, the microstructure of the CoFeB / NiPS3 heterostructure prepared by this invention exhibits a 2D / 2D vertically grown heterostructure with a large number of exposed surface active sites, providing a new approach for the preparation of advanced two-dimensional materials. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art are briefly introduced below; obviously, the drawings described below are some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0037] Figure 1 This is a side view of a NiPS3 block in an embodiment of the present invention;

[0038] Figure 2 This is a schematic diagram of NiPS3 nanosheets obtained by the electrochemical cathode exfoliation method in Example 1 of the present invention; wherein, Figure 2 Image (a) is a scanning electron microscope (SEM) image. Figure 2 Image (b) is a transmission electron microscope (TEM) image; Figure 2 (c) is the elemental energy spectrum obtained by transmission electron microscopy; Figure 2 In the middle (d), (e), and (f), the peak diagrams of Ni, P, and S elements in the X-ray photoelectron spectroscopy (XPS) diagrams are shown respectively.

[0039] Figure 3 This is a schematic diagram of the CoFeB / NiPS3 heterostructure prepared in Example 1 of the present invention; wherein, Figure 3 Image (a) is a scanning electron microscope (SEM) image. Figure 3 Image (b) is a transmission electron microscope (TEM) image; Figure 3 (c) is the elemental energy spectrum obtained by transmission electron microscopy; Figure 3 In the image, (d), (e), (f), (g), (h), and (i) are the peak diagrams of Co, Fe, B, Ni, P, and S elements in the X-ray photoelectron spectroscopy (XPS) diagram, respectively.

[0040] Figure 4 This is a schematic diagram of the oxygen evolution performance of the composite material CoFeB / NiPS3 in 1M KOH solution in Examples 1, 2, 3 and 4 of the present invention;

[0041] Figure 5 These are the XRD patterns of the CoFeB / NiPS3 composite material in Examples 1, 2, 3, and 4 of this invention;

[0042] Figure 6 This is a schematic diagram illustrating the oxygen evolution reaction stability of the CoFeB / NiPS3 heterostructure prepared in Example 1 of this invention. Detailed Implementation

[0043] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the present invention.

[0044] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0045] It should be noted that the process equipment or apparatus not specifically mentioned in the following embodiments are all conventional equipment or apparatus in the art.

[0046] Furthermore, it should be understood that the existence of other method steps before or after the combined steps, or the insertion of other method steps between these explicitly mentioned steps, does not preclude the existence of other method steps before or after the combined steps, or the insertion of other method steps between these explicitly mentioned steps, unless otherwise stated. It should also be understood that the combined connection relationship between one or more devices / apparatus mentioned in this invention does not preclude the existence of other devices / apparatus before or after the combined devices / apparatus, or the insertion of other devices / apparatus between these explicitly mentioned devices / apparatus, unless otherwise stated. Moreover, unless otherwise stated, the numbering of each method step is merely a convenient tool for identifying each method step, and not for limiting the order of the method steps or limiting the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention.

[0047] The present invention provides a method for preparing a fully transition metal-based oxygen evolution electrocatalyst, comprising the following steps:

[0048] NiPS3 nanosheets were placed in a mixed aqueous solution of cobalt and iron metal salts, mixed thoroughly, and then centrifuged to obtain a precipitate; ultrasonic mixing can be used to achieve uniform mixing.

[0049] Under stirring conditions, the obtained precipitate is dispersed in water to obtain a mixed aqueous solution of the precipitate;

[0050] A reducing agent containing element B was added to the mixed aqueous solution of the precipitate at a temperature below room temperature. The reaction was carried out under stirring, followed by centrifugation, washing, and drying to prepare the CoFeB / NiPS3 heterostructure.

[0051] The preparation method provided in this invention has the advantages of simple preparation process, high yield and low time cost; the prepared all-transition metal-based oxygen evolution catalyst has the advantage of low cost compared with noble metal catalysts, and its catalytic performance and stability are comparable to those of noble metal catalysts.

[0052] In a specific exemplary embodiment of the present invention, the preparation steps of NiPS3 nanosheets include: inserting an anode with a platinum wire and a cathode with a NiPS3 block into an electrolytic cell, applying a preset voltage for electrochemical cathode stripping, and after stripping, performing ultrasonication, centrifugation, and washing to obtain NiPS3 nanosheets; wherein, the solvent in the electrolytic cell is N,N-dimethylformamide, and the solute is tetrahexylammonium bromide; in a further preferred embodiment, the NiPS3 block is placed in a titanium mesh connected to the cathode; during washing, it is washed multiple times sequentially with deionized water and ethanol; in a further preferred embodiment, every 30 mg of NiPS3 block corresponds to 0.45 g to 0.50 g of tetrahexylammonium bromide and 20 ml of N,N-dimethylformamide; in addition, the preset voltage is 5V to 10V.

[0053] In a further preferred embodiment of the present invention, the molar ratio of cobalt metal salt to iron metal salt in the mixed aqueous solution of the cobalt metal salt and iron metal salt is (0.5-4):1. This embodiment further limits the molar ratio of cobalt metal salt and iron metal salt, which can further promote the generation of 2D / 2D vertically grown heterostructures. Specifically, the cobalt metal salt is one or more of cobalt nitrate, cobalt acetate, cobalt chloride, and cobalt sulfate; the iron metal salt is one or two of ferrous sulfate and ferrous chloride.

[0054] In a further preferred embodiment of the present invention, the solvent used in the mixed aqueous solution of the cobalt metal salt and the iron metal salt, as well as the mixed aqueous solution of the precipitate, is nitrogen-saturated deionized water. This embodiment further specifies nitrogen-saturated deionized water as the solvent to prevent the generated transition metal borides from being rapidly oxidized, thus avoiding the formation of boron oxides and affecting the oxygen evolution performance and microstructure of the electrocatalyst. Specifically, 0.002345 mol of Co can be added to every 35 ml of nitrogen-saturated deionized water. 2+ and 0.001173 mol of Fe 2+ .

[0055] In a further preferred embodiment of the present invention, an aqueous solution containing a reducing agent of element B is added to the mixed aqueous solution of the precipitate at a preset flow rate to avoid aggregation of the reducing agent; wherein, the solvent of the aqueous solution containing the reducing agent of element B is nitrogen-saturated deionized water, and the solute is sodium borohydride or potassium borohydride. Specifically, the flow rate can be 0.5–1 ml / min; wherein, for every 0.002345 mol of Co 2+ and 0.001173 mol of Fe 2+ For 0.003 mol of sodium borohydride, adding a reducing agent containing element B dropwise at a set flow rate ensures a complete reaction between the reducing agent and the substances in the solution, preventing the reducing agent from agglomerating. Furthermore, limiting the reaction temperature to 8℃~15℃ further promotes the formation of 2D / 2D vertically growing heterostructures. For example, stirring can be performed during the reaction, and washing can be done repeatedly with deionized water and ethanol sequentially.

[0056] The fully transition metal-based oxygen evolution catalyst prepared by the method provided in this invention is used as an anodic oxygen evolution reaction catalyst in the water electrolysis process. Explanatoryly, the fully transition metal-based oxygen evolution reaction electrocatalyst has a CoFeB / NiPS3 heterostructure, wherein the transition metals are cobalt, iron, and nickel.

[0057] The CoFeB / NiPS3 heterostructure prepared in the embodiments of the present invention exhibits a 2D / 2D vertically grown heterostructure with a large number of exposed surface active sites; the prepared fully transition metal-based oxygen evolution electrocatalyst is a low-cost, efficient and stable electrocatalyst with excellent oxygen evolution performance and stability.

[0058] Example 1

[0059] Please see Figures 1 to 6 The present invention provides a method for preparing an all-transition metal-based oxygen evolution reaction electrocatalyst, which uses an electrochemical cathode exfoliation method to prepare sheet-like NiPS3, introduces Co and Fe ions, and adds sodium borohydride as a reducing agent to obtain a CoFeB / NiPS3 heterostructure.

[0060] Specifically, the 30mg NiPS3 bulk material is wrapped with platinum wire at the anode and titanium mesh at the cathode. Please refer to the microscopic side view of the bulk material. Figure 1 The anode and cathode were inserted into an electrolytic cell containing 20 ml of N,N-dimethylformamide and 435 mg of tetrahexylammonium bromide. An electrochemical cathode stripping method was performed by applying a preset voltage of 10 V. After stripping, the nanosheets were ultrasonicated, centrifuged, and washed repeatedly with deionized water and ethanol to obtain NiPS3 nanosheets. For the microstructure, please refer to [reference needed]. Figure 2 ;

[0061] Prepare a 35 ml mixed aqueous solution containing 1318 mg cobalt sulfate and 642 mg ferrous sulfate. Place the NiPS3 nanosheets obtained by the electrochemical cathode exfoliation method into the mixed aqueous solution of cobalt salt and iron salt, sonicate until uniformly mixed, and centrifuge to obtain the precipitate.

[0062] Under stirring conditions, the obtained precipitate was redispersed in 35 ml of nitrogen-saturated deionized water. Under ice bath conditions, 5 ml of an aqueous solution containing 227 mg of sodium borohydride was added dropwise to the mixed aqueous solution at a flow rate of 1 ml / min. After stirring for 1 hour, the precipitate was obtained by centrifugation and washed repeatedly with deionized water and ethanol, and then dried to obtain the CoFeB / NiPS3 heterostructure. Please refer to the scanning electron microscope image for details. Figure 3 (a) Figure 3 Images (b)-(c) show high-resolution transmission images and elemental distribution diagrams. As can be seen, the CoFeB / NiPS3 prepared in Example 1 of this invention exhibits a 2D / 2D vertical heterostructure with uniform elemental distribution. CoFeB is amorphous, while NiPS3 is crystalline. For detailed elemental spectra, please refer to [link to detailed spectra diagrams]. Figure 3 (d)-(i); Please refer to the X-ray diffraction patterns. Figure 5 .

[0063] The all-transition metal-based heterostructure prepared in this invention can serve as a highly efficient and stable electrocatalyst for the oxygen evolution reaction (OER). The OER performance of this material was tested as follows: 4 mg of the electrocatalyst prepared in this invention was mixed and ground with 1 mg of acetylene black. 450 μL of ethanol, 30 μL of deionized water, and 20 μL of Nafion were added. The mixture was ultrasonicated until homogeneous. 10 μL of the homogeneous suspension was then pipetted onto a glassy carbon electrode (3 mm in diameter) in several portions. After drying, this electrode was used as the working electrode, a carbon rod as the counter electrode, and an Ag / AgCl electrode as the reference electrode. The OER performance was tested using an electrochemical workstation (Autolab) in an alkaline solution (1 M KOH). The test results are available in the [reference needed]. Figure 4 .

[0064] Tests have shown that the oxygen evolution performance and stability of the fully transition metal-based heterostructure of this invention are superior to those of the commercial catalyst ruthenium dioxide. Please refer to [link / reference]. Figure 4 and Figure 6 The CoFeB / NiPS3 heterostructure prepared in this embodiment of the invention has a 50 mA / cm² thickness. -2 At a current density of 20 mA / cm², its overpotential is 285 mV, which is significantly better than that of the commercial catalyst ruthenium dioxide at 20 mA / cm². -2 The overpotential at the current density is 400 mV. Simultaneously, this heterostructure exhibits superior stability compared to commercial catalysts within 24 hours.

[0065] Example 2

[0066] This invention provides a method for preparing a fully transition metal-based oxygen evolution reaction electrocatalyst, wherein the fully transition metal-based oxygen evolution reaction electrocatalyst has a CoFeB / NiPS3 heterostructure, and the specific steps include:

[0067] A 30mg NiPS3 bulk material, encased in a platinum wire anode and a titanium mesh cathode, is shown in the microscopic side view of the bulk material. Figure 1 The anode and cathode were inserted into an electrolytic cell containing 20 ml of N,N-dimethylformamide and 435 mg of tetrahexylammonium bromide. An electrochemical cathode stripping method was performed by applying a preset voltage of 10 V. After stripping, the nanosheets were ultrasonicated, centrifuged, and washed repeatedly with deionized water and ethanol to obtain NiPS3 nanosheets. (See [link to relevant documentation]). Figure 2 Prepare a 35 ml mixed aqueous solution containing 330 mg cobalt sulfate and 161 mg ferrous sulfate. Place NiPS3 nanosheets obtained by the electrochemical cathode exfoliation method into the mixed aqueous solution of cobalt and iron salts. Sonicate until homogeneous, then centrifuge to obtain a precipitate. Subsequently, under stirring, redisperse the precipitate in 35 ml of nitrogen-saturated deionized water. Under ice bath conditions, add 5 ml of sodium borohydride aqueous solution containing 57 mg dropwise to the mixed aqueous solution at a flow rate of 1 ml / min. After stirring for 1 hour, centrifuge to obtain the precipitate, wash repeatedly with deionized water and ethanol, and then dry to obtain the CoFeB / NiPS3 heterostructure. See the X-ray diffraction pattern for details. Figure 5 .

[0068] The oxygen evolution performance of the fully transition metal-based heterostructure of this invention is superior to that of the commercial catalyst ruthenium dioxide. Please refer to [link / reference]. Figure 4 The CoFeB / NiPS3 heterostructure prepared in this embodiment of the invention has a 50 mA cm⁻¹ diameter. -2 At a current density of 20 mA / cm², its overpotential is 308 mV, which is significantly better than that of the commercial catalyst ruthenium dioxide at 20 mA / cm². -2 The overpotential at the current density is 400mV.

[0069] Example 3

[0070] This invention provides a method for preparing a fully transition metal-based oxygen evolution reaction electrocatalyst, wherein the fully transition metal-based oxygen evolution reaction electrocatalyst has a CoFeB / NiPS3 heterostructure, and the specific steps include:

[0071] A 30mg NiPS3 bulk material, encased in a platinum wire anode and a titanium mesh cathode, is shown in the microscopic side view of the bulk material. Figure 1The anode and cathode were inserted into an electrolytic cell containing 20 ml of N,N-dimethylformamide and 435 mg of tetrahexylammonium bromide. An electrochemical cathode stripping method was performed by applying a preset voltage of 10 V. After stripping, the nanosheets were ultrasonicated, centrifuged, and washed repeatedly with deionized water and ethanol to obtain NiPS3 nanosheets. (See [link to relevant documentation]). Figure 2 Prepare a 35 ml mixed aqueous solution containing 659 mg cobalt sulfate and 321 mg ferrous sulfate. Place NiPS3 nanosheets obtained by the electrochemical cathode exfoliation method into the mixed aqueous solution of cobalt and ferrous salts. Sonicate until homogeneous, then centrifuge to obtain a precipitate. Subsequently, under stirring, redisperse the precipitate in 35 ml of nitrogen-saturated deionized water. Under ice bath conditions, add 5 ml of sodium borohydride aqueous solution containing 113 mg dropwise to the mixed aqueous solution at a flow rate of 1 ml / min. After stirring for 1 hour, centrifuge to obtain the precipitate, wash repeatedly with deionized water and ethanol, and then dry to obtain the CoFeB / NiPS3 heterostructure. See the X-ray diffraction pattern for details. Figure 5 .

[0072] The oxygen evolution performance of the fully transition metal-based heterostructure of this invention is superior to that of the commercial catalyst ruthenium dioxide. Please refer to [link / reference]. Figure 4 The prepared CoFeB / NiPS3 heterostructure has a 50 mA cm⁻¹ diameter. -2 At a current density of 20 mA / cm², its overpotential is 305 mV, which is significantly better than that of the commercial catalyst ruthenium dioxide at 20 mA / cm². -2 The overpotential at the current density is 400mV.

[0073] Example 4

[0074] This invention discloses a method for preparing a fully transition metal-based oxygen evolution reaction (OER) electrocatalyst, wherein the fully transition metal-based OER electrocatalyst is a CoFeB / NiPS3 heterostructure. The specific steps include: a platinum wire sandwiched at the anode, and a 30mg NiPS3 bulk material wrapped with a titanium mesh sandwiched at the cathode. A microscopic side view of the bulk material can be found in the provided text. Figure 1 The anode and cathode were inserted into an electrolytic cell containing 20 ml of N,N-dimethylformamide and 435 mg of tetrahexylammonium bromide. An electrochemical cathode stripping method was performed by applying a preset voltage of 10 V. After stripping, the nanosheets were ultrasonicated, centrifuged, and washed repeatedly with deionized water and ethanol to obtain NiPS3 nanosheets. (See [link to relevant documentation]). Figure 2Prepare a 35 ml mixed aqueous solution containing 2637 mg cobalt sulfate and 1284 mg ferrous sulfate. Place NiPS3 nanosheets obtained by the electrochemical cathode exfoliation method into the mixed aqueous solution of cobalt and iron salts. Sonicate until homogeneous, then centrifuge to obtain a precipitate. Subsequently, under stirring, redisperse the precipitate in 35 ml of nitrogen-saturated deionized water. Under ice bath conditions, add 5 ml of an aqueous solution containing 454 mg sodium borohydride dropwise to the mixed aqueous solution at a flow rate of 1 ml / min. After stirring for 1 hour, centrifuge to obtain the precipitate, wash repeatedly with deionized water and ethanol, and then dry to obtain the CoFeB / NiPS3 heterostructure. See [reference needed for X-ray diffraction pattern] for its X-ray diffraction pattern. Figure 5 .

[0075] The oxygen evolution performance of the fully transition metal-based heterostructure of this invention is superior to that of the commercial catalyst ruthenium dioxide. Please refer to [link / reference]. Figure 4 The prepared CoFeB / NiPS3 heterostructure has a 50 mA cm⁻¹ diameter. -2 At a current density of 20 mA / cm², its overpotential is 315 mV, which is significantly better than that of the commercial catalyst ruthenium dioxide at 20 mA / cm². -2 The overpotential at the current density is 400mV.

[0076] Example 5

[0077] This invention provides a method for preparing a fully transition metal-based oxygen evolution electrocatalyst, comprising:

[0078] NiPS3 nanosheets were placed in a mixed aqueous solution of cobalt metal salt and iron metal salt, mixed thoroughly, and then centrifuged to obtain a precipitate. The molar ratio of cobalt metal salt to iron metal salt was 0.5:1, and the solvent of the mixed aqueous solution was nitrogen-saturated deionized water. The cobalt metal salt was cobalt nitrate, and the iron metal salt was ferrous sulfate.

[0079] Under stirring conditions, the obtained precipitate is dispersed in water to obtain a mixed aqueous solution of the precipitate; wherein the solvent of the mixed aqueous solution is nitrogen-saturated deionized water;

[0080] Under conditions below room temperature, a reducing agent containing element B is added to the mixed aqueous solution of the precipitate, and the reaction is carried out under stirring. After centrifugation, washing, and drying, a CoFeB / NiPS3 heterostructure is obtained. Specifically, the reaction temperature is 8°C. The step of adding the reducing agent containing element B to the mixed aqueous solution of the precipitate is to add the aqueous solution of the reducing agent containing element B to the mixed aqueous solution of the precipitate at a preset flow rate to avoid the aggregation of the reducing agent. The solvent of the aqueous solution of the reducing agent containing element B is nitrogen-saturated deionized water, and the solute is sodium borohydride.

[0081] Example 6

[0082] This invention provides a method for preparing a fully transition metal-based oxygen evolution electrocatalyst, comprising:

[0083] NiPS3 nanosheets were placed in a mixed aqueous solution of cobalt and iron metal salts, mixed thoroughly, and then centrifuged to obtain a precipitate. The molar ratio of cobalt metal salt to iron metal salt was 2:1, and the solvent of the mixed aqueous solution was nitrogen-saturated deionized water. The cobalt metal salt was cobalt sulfate, and the iron metal salt was ferrous chloride.

[0084] Under stirring conditions, the obtained precipitate is dispersed in water to obtain a mixed aqueous solution of the precipitate; wherein the solvent of the mixed aqueous solution is nitrogen-saturated deionized water;

[0085] Under conditions below room temperature, a reducing agent containing element B is added to the mixed aqueous solution of the precipitate, and the reaction is carried out under stirring. After centrifugation, washing, and drying, a CoFeB / NiPS3 heterostructure is obtained. Specifically, the reaction temperature is 10°C. The step of adding the reducing agent containing element B to the mixed aqueous solution of the precipitate is to add the aqueous solution of the reducing agent containing element B to the mixed aqueous solution of the precipitate at a preset flow rate to avoid the aggregation of the reducing agent. The solvent of the aqueous solution of the reducing agent containing element B is nitrogen-saturated deionized water, and the solute is potassium borohydride.

[0086] Example 7

[0087] This invention provides a method for preparing a fully transition metal-based oxygen evolution electrocatalyst, comprising:

[0088] NiPS3 nanosheets were placed in a mixed aqueous solution of cobalt and iron metal salts, mixed thoroughly, and then centrifuged to obtain a precipitate. The molar ratio of cobalt metal salt to iron metal salt was 4:1, and the solvent of the mixed aqueous solution was nitrogen-saturated deionized water. The cobalt metal salt was a mixture of cobalt nitrate, cobalt acetate, cobalt chloride, and cobalt sulfate. The iron metal salt was a mixture of ferrous sulfate and ferrous chloride.

[0089] Under stirring conditions, the obtained precipitate is dispersed in water to obtain a mixed aqueous solution of the precipitate; wherein the solvent of the mixed aqueous solution is nitrogen-saturated deionized water;

[0090] Under conditions below room temperature, a reducing agent containing element B is added to the mixed aqueous solution of the precipitate, and the reaction is carried out under stirring. After centrifugation, washing, and drying, a CoFeB / NiPS3 heterostructure is obtained. Specifically, the reaction temperature is 15°C. The step of adding the reducing agent containing element B to the mixed aqueous solution of the precipitate is to add the aqueous solution of the reducing agent containing element B to the mixed aqueous solution of the precipitate at a preset flow rate to avoid the aggregation of the reducing agent. The solvent of the aqueous solution of the reducing agent containing element B is nitrogen-saturated deionized water, and the solute is a mixture of sodium borohydride and potassium borohydride.

[0091] In summary, this invention discloses a method for preparing a fully transition metal-based oxygen evolution reaction (OER) electrocatalyst. NiPS3 nanosheets are used, and Co and Fe ions are introduced. Sodium borohydride is added dropwise as a reducing agent to obtain a CoFeB / NiPS3 heterostructure. The prepared fully transition metal-based OER electrocatalyst, a CoFeB / NiPS3 heterostructure, is a low-cost, highly efficient, and stable electrocatalyst with excellent OER performance and stability, suitable for industrial applications, and achieving full utilization of resources and energy. It is important to emphasize that the fully transition metal-based phosphorus sulfide catalyst prepared by this invention has the advantage of low cost compared to noble metal catalysts, while its catalytic performance and stability are comparable to those of noble metal catalysts.

[0092] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a fully transition metal-based oxygen evolution electrocatalyst, characterized in that, include: NiPS3 nanosheets were placed in a mixed aqueous solution of cobalt metal salt and iron metal salt, mixed evenly, and then centrifuged to obtain a precipitate. Under stirring conditions, the obtained precipitate is dispersed in water to obtain a mixed aqueous solution of the precipitate; A reducing agent containing element B was added to the mixed aqueous solution of the precipitate at a temperature below room temperature. The reaction was carried out under stirring, followed by centrifugation, washing, and drying to prepare the CoFeB / NiPS3 heterostructure.

2. The method for preparing a fully transition metal-based oxygen evolution electrocatalyst according to claim 1, characterized in that, In the mixed aqueous solution of cobalt metal salt and iron metal salt, the molar ratio of cobalt metal salt to iron metal salt is (0.5-4):

1.

3. The method for preparing a fully transition metal-based oxygen evolution electrocatalyst according to claim 1, characterized in that, The solvent used in the mixed aqueous solution of the cobalt metal salt and the iron metal salt, as well as the mixed aqueous solution of the precipitate, is nitrogen-saturated deionized water.

4. The method for preparing a fully transition metal-based oxygen evolution electrocatalyst according to claim 1, characterized in that, The cobalt metal salt is one or more of cobalt nitrate, cobalt acetate, cobalt chloride, and cobalt sulfate; The iron metal salt is one or more of ferrous sulfate and ferrous chloride.

5. The method for preparing a fully transition metal-based oxygen evolution electrocatalyst according to claim 1, characterized in that, The reducing agent containing element B is sodium borohydride or potassium borohydride.

6. The method for preparing a fully transition metal-based oxygen evolution electrocatalyst according to claim 5, characterized in that, The step of adding a reducing agent containing element B to the mixed aqueous solution of the precipitate is as follows: An aqueous solution containing a reducing agent of element B is added to the mixed aqueous solution of the precipitate at a preset flow rate to avoid the aggregation of the reducing agent; The solvent in the aqueous solution of the reducing agent containing element B is nitrogen-saturated deionized water.

7. The method for preparing a fully transition metal-based oxygen evolution electrocatalyst according to claim 1, characterized in that, The temperature conditions below room temperature are specifically as follows: Temperature conditions of 8℃~15℃.

8. The method for preparing a fully transition metal-based oxygen evolution electrocatalyst according to claim 1, characterized in that, The method for preparing the NiPS3 nanosheets includes: The anode with platinum wire and the cathode with NiPS3 bulk were inserted into an electrolytic cell, and an electrochemical cathode stripping was performed by applying a voltage of 5V to 10V. After stripping, the cathode was subjected to ultrasonication, centrifugation and washing to obtain NiPS3 nanosheets. The solvent in the electrolytic cell is N,N-dimethylformamide, and the solute is tetrahexylammonium bromide.

9. A fully transition metal-based oxygen evolution electrocatalyst prepared by the method according to any one of claims 1 to 8, characterized in that, The fully transition metal-based oxygen evolution electrocatalyst has a CoFeB / NiPS3 heterostructure. The transition metals in the CoFeB / NiPS3 heterostructure are cobalt, iron, and nickel, and the heterostructure exhibits a 2D / 2D vertical growth microstructure.

10. The application of the all-transition metal-based oxygen evolution electrocatalyst according to claim 9, characterized in that, The fully transition metal-based oxygen evolution electrocatalyst is used as an anodic oxygen evolution reaction catalyst in the water electrolysis process.

Images