阅读说明：本技术 基于过渡金属盐的析氧电催化材料、其制备方法及应用 (Oxygen evolution electrocatalytic material based on transition metal salt, preparation method and application thereof ) 是由 刘守清 周漪雯 于 2021-07-09 设计创作，主要内容包括：本发明公开了一种基于过渡金属盐的析氧电催化材料、其制备方法及应用。所述析氧电催化材料可以通过采用钴离子作为中心离子,掺杂一定量镍离子,以钾离子或钠离子为电荷平衡离子,以氟离子为配体,通过钴离子与配体在溶剂中的配位反应制得。并且所述析氧电催化材料在应用于电解水制氢时的析氧过电位明显低于铱电极,表现出优异的析氧电催化性能和电催化稳定性,有望在新能源领域得到广泛应用。(The invention discloses an oxygen evolution electrocatalytic material based on transition metal salt, and a preparation method and application thereof. The oxygen evolution electrocatalytic material can be prepared by adopting cobalt ions as central ions, doping a certain amount of nickel ions, taking potassium ions or sodium ions as charge balance ions, taking fluorine ions as ligands and carrying out coordination reaction on the cobalt ions and the ligands in a solvent. And the oxygen evolution over-potential of the oxygen evolution electrocatalytic material is obviously lower than that of an iridium electrode when the material is applied to hydrogen production by water electrolysis, the material shows excellent oxygen evolution electrocatalytic performance and electrocatalytic stability, and is expected to be widely applied in the field of new energy.)

1. A preparation method of an oxygen evolution electrocatalytic material based on transition metal salt is characterized by comprising the following steps: reacting a uniform liquid phase mixed reaction system containing hydrogen fluoride, hydroxide, cobalt salt and nickel salt at-2-99 ℃ for 0.5-2h under the protection of nitrogen to obtain the oxygen evolution electrocatalytic material based on the transition metal salt, wherein the chemical formula of the material is MCo_(1-x)Ni_xF₃M represents a charge-balancing ion, 0 < x < 1.

2. The production method according to claim 1, characterized by comprising: introducing nitrogen into the uniform liquid phase mixed reaction system to remove oxygen for more than 20 minutes; and/or, M comprises potassium and/or sodium ions.

3. The method according to claim 1, comprising:

adding electrolyte into the mixed solution of hydrogen fluoride and hydroxide, and controlling the temperature of the mixed solution to be below-2 ℃;

and mixing and grinding cobalt salt and nickel salt, directly adding the mixture into the mixed solution, carrying out ultrasonic oscillation, heating to 85-99 ℃, and continuing to react for 0.5-2h to obtain the oxygen evolution electro-catalytic material based on the transition metal salt.

4. The method of claim 1, wherein: the electrolyte comprises any one or the combination of more than two of potassium sulfate, sodium sulfate, potassium nitrate, sodium nitrate, potassium chloride, sodium chloride, calcium chloride and glucose; and/or the time of the ultrasonic oscillation is less than 10 h.

5. The production method according to claim 3, characterized by comprising: the hydroxide comprises potassium hydroxide and/or sodium hydroxide.

6. The method of claim 1, wherein: the molar ratio of the nickel salt to the cobalt salt is y: 1, wherein y > 0, preferably 0 < y < 1; and/or the cobalt salt comprises any one or the combination of more than two of cobalt sulfate, cobalt chloride and cobalt nitrate; and/or the nickel salt comprises any one or the combination of more than two of nickel sulfate, nickel chloride and nickel nitrate.

7. The method of claim 1, further comprising: and after the reaction is finished, standing for layering, separating out solids, washing and drying to obtain the oxygen evolution electrocatalytic material based on the transition metal salt.

8. Transition metal salt-based oxygen evolution electrocatalytic material prepared by the method of any one of claims 1-7, having a crystal structure of perovskite type cubic system with a space group of P_m3_mSpace group with chemical formula of MCo_(1-x)Ni_xF₃M represents a charge-balancing ion, 0 < x < 1, preferably M comprises potassium and/or sodium ions.

9. Use of the transition metal salt based oxygen evolution electrocatalytic material as defined in claim 8 as an oxygen evolution electrocatalyst for the electrolysis of water for hydrogen production.

10. A method for producing hydrogen by electrolyzing water is characterized by comprising the following steps:

forming the transition metal salt based oxygen evolution electrocatalytic material of claim 8 into a carbon paste electrode or a metal-based electrode;

the carbon paste electrode or the metal-based electrode is used as an oxygen evolution electrode, the nickel is used as a hydrogen evolution electrode, the carbon paste electrode or the metal-based electrode is matched with an alkaline aqueous solution to form a water electrolysis hydrogen production system, and the water electrolysis hydrogen production is realized by electrifying the oxygen evolution electrode and the hydrogen evolution electrode.

Technical Field

The invention relates to an electrocatalytic oxygen evolution material, in particular to a preparation method of an oxygen evolution electrocatalytic material based on transition metal salt by taking cobalt ions as coordination center ions and fluorine ions as ligands, and application thereof in electrocatalytic oxygen evolution in hydrogen production by water electrolysis, belonging to the technical field of renewable energy materials.

Background

At present, photovoltaic power generation, wind power generation and hydroelectric power generation are utilized, and then water electrolysis and hydrogen evolution are effective ways for realizing carbon peak-reaching carbon neutralization. Most of the existing methods for separating hydrogen by electrolyzing water need to adopt noble metals such as ruthenium, iridium and oxides thereof as oxygen-separating electrocatalysts, and although the noble metals have excellent oxygen-separating performance, the noble metals are expensive and have limited reserves, so the method is difficult to be applied on a large scale. For a long time, the industry is keenly to develop cheap and efficient non-noble metal electrocatalysts to realize low-cost hydrogen production by water electrolysis.

Although researchers propose that some transition metal oxides or hydroxides are expected to be used as oxygen evolution electrocatalytic materials, the oxygen evolution overpotential of the transition metal oxides or hydroxides is too large, and excessive hydrogen ions generated by oxygen evolution can generate local dissolution effect on the transition metal oxide or hydroxide electrodes, so that the electrolysis efficiency and the service life of the transition metal oxide or hydroxide electrodes are influenced, and the requirements of practical application cannot be met.

Disclosure of Invention

In order to overcome the defects of the existing water electrolysis oxygen evolution electrocatalyst, reduce energy consumption and improve current efficiency, the invention aims to design a novel transition metal salt-based oxygen evolution electrocatalytic material, a preparation method thereof and application in the aspect of water electrolysis hydrogen production.

In order to achieve the purpose, the technical scheme adopted by the invention comprises the following steps:

the embodiment of the invention provides a preparation method of an oxygen evolution electrocatalytic material based on transition metal salt, which comprises the following steps: reacting a uniform liquid phase mixed reaction system containing hydrogen fluoride, hydroxide, cobalt salt and nickel salt at-2-99 ℃ for 0.5-2h under the protection of nitrogen to obtain the oxygen evolution electrocatalytic material based on the transition metal salt, wherein the chemical formula of the material is MCo_(1-x)Ni_xF₃M represents a charge-balancing ion, 0 < x < 1.

In some embodiments, the preparation method specifically comprises:

adding electrolyte into the mixed solution of hydrogen fluoride and hydroxide, and controlling the temperature of the mixed solution to be below-2 ℃;

and mixing and grinding cobalt salt and nickel salt, directly adding the mixture into the mixed solution, carrying out ultrasonic oscillation, heating to 85-99 ℃, and continuing to react for 0.5-2h to obtain the oxygen evolution electro-catalytic material based on the transition metal salt.

In some embodiments, the molar ratio of nickel salt to cobalt salt is y: 1, wherein y > 0, preferably 0 < y < 1.

The embodiment of the invention also provides the oxygen evolution electrocatalytic material based on the transition metal salt prepared by the method, the crystal structure of the material is a perovskite type cubic crystal system, and the space group is P_m3_mSpace group with chemical formula of MCo_(1-x)Ni_xF₃M represents a charge-balancing ion, 0 < x < 1.

The embodiment of the invention also provides application of the transition metal salt-based oxygen evolution electro-catalytic material as an oxygen evolution electro-catalyst in hydrogen production by water electrolysis.

Correspondingly, the embodiment of the invention also provides a method for producing hydrogen by electrolyzing water, which comprises the following steps:

preparing the oxygen evolution electrocatalytic material based on the transition metal salt into a carbon paste electrode or a metal-based electrode;

the carbon paste electrode or the metal-based electrode is used as an oxygen evolution electrode, the nickel is used as a hydrogen evolution electrode, the carbon paste electrode or the metal-based electrode is matched with an alkaline aqueous solution to form a water electrolysis hydrogen production system, and the water electrolysis hydrogen production is realized by electrifying the oxygen evolution electrode and the hydrogen evolution electrode.

Compared with the prior art, the oxygen evolution electrocatalytic material based on the transition metal salt is generated by adopting cobalt ions as central ions, doping a certain amount of nickel ions, adopting potassium ions or sodium ions as charge balance ions and adopting fluorine ions as ligands through the coordination reaction of the cobalt ions and the ligands in a solvent, has an oxygen evolution overpotential obviously lower than that of an iridium electrode when being applied to hydrogen production by water electrolysis, shows excellent oxygen evolution electrocatalytic performance and electrocatalytic stability, and is expected to be widely applied in the field of new energy.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments described in the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 shows KNiF in an exemplary embodiment of the invention₃、KCoF₃、KCo_0.75Ni_0.25F₃X-ray powder diffractogram of;

FIG. 2A is KCo in an exemplary embodiment of the invention_0.75Ni_0.25F₃Transmission electron microscopy images of;

FIG. 2B is KCo in an exemplary embodiment of the invention_0.75Ni_0.25F₃Electron diffraction pattern of (3);

FIG. 2C is KCo in an exemplary embodiment of the invention_0.75Ni_0.25F₃High power transmission electron micrographs of;

FIG. 2D shows KNiF in an exemplary embodiment of the invention₃Transmission electron microscopy images of;

FIG. 2E shows KNiF in an exemplary embodiment of the invention₃Electron diffraction pattern of (3);

FIG. 2F shows KNiF in an exemplary embodiment of the invention₃High power transmission electron micrographs of;

FIG. 2G is a KCoF in an exemplary embodiment of the invention₃Transmission electron microscopy images of;

FIG. 2H shows KCoF in an exemplary embodiment of the invention₃Electron diffraction pattern of (3);

FIG. 2I is a KCoF in an exemplary embodiment of the invention₃High power transmission electron micrographs of;

FIG. 3 is a KCo in an exemplary embodiment of the invention_0.7sNi_0.25F₃EDX energy spectrum of (a);

FIG. 4 shows a graphite, KNiF, example of an exemplary embodiment of the present invention₃、KCo_0.5Ni_0.5F₃、IrO₂、KCoF₃、KCo_0.2sNi_0.75F₃、KCo_0.75Ni_0.25F₃Wherein curve a represents graphite and curve b represents KNiF₃Curve c represents KCo_0.5Ni_0.5F₃Curve d represents IrO₂Curve e represents KCoF₃Curve f represents KCo_0.25Ni_0.75F₃Curve g represents KCo_0.75Ni_0.25F₃；

FIG. 5 is a KCo in an exemplary embodiment of the invention_0.75Ni_0.25F₃Graph of oxygen evolution i-t.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention are described in detail below with reference to the accompanying drawings. Examples of these preferred embodiments are illustrated in the accompanying drawings. The embodiments of the invention shown in the drawings and described in accordance with the drawings are exemplary only, and the invention is not limited to these embodiments.

It should be noted that, in order to avoid obscuring the present invention with unnecessary details, only the structures and/or processing steps that are closely related to the solution according to the present invention are shown in the drawings, and other details that are not so relevant to the present invention are omitted.

One aspect of the embodiment of the invention provides a preparation method of a novel transition metal salt-based oxygen evolution electrocatalytic material and application of the material in hydrogen production by water electrolysis. The preparation method adopts cobalt ions as central ions, a certain amount of nickel ions are doped, potassium ions or sodium ions are used as charge balance ions, fluorine ions are used as ligands, and the novel oxygen evolution electrocatalytic material based on transition metal salt is generated through the coordination reaction of the cobalt ions and the ligands in a solvent.

In some exemplary embodiments, the preparation method comprises: reacting a uniform liquid phase mixed reaction system containing hydrogen fluoride, hydroxide, cobalt salt and nickel salt at-2-99 ℃ for 0.5-2h under the protection of nitrogen to obtain the oxygen evolution electrocatalytic material based on the transition metal salt, wherein the chemical formula of the material is MCo_(1-x)Fe_xF₃M represents a charge-balancing ion, 0 < x < 1.

Further, M includes potassium ion, sodium ion, etc., but is not limited thereto.

In some exemplary embodiments, the preparation method further comprises: and introducing nitrogen into the uniform liquid phase mixed reaction system to remove oxygen for more than 20 minutes.

In some exemplary embodiments, the preparation method specifically includes:

adding electrolyte into the mixed solution of hydrogen fluoride and hydroxide, introducing nitrogen to remove oxygen for more than 20 minutes, and controlling the temperature of the mixed solution to be below-2 ℃;

and grinding cobalt salt and nickel salt, directly adding the ground cobalt salt and nickel salt into the mixed solution which is introduced with nitrogen and deaerated, carrying out ultrasonic oscillation, then heating to 85-99 ℃, and continuing to react for 0.5-2h to obtain the oxygen evolution electrocatalytic material based on the transition metal salt.

In other exemplary embodiments, the preparation method may further include: directly taking fluoride solution, introducing nitrogen to remove oxygen for more than 20 minutes, and controlling the temperature of the solution to be-2 ℃ in order to prevent metal ions from hydrolysis. To reach-2 ℃, electrolyte was added according to the principle of colligative properties.

Further, the fluoride used in the present invention includes potassium fluoride, sodium fluoride, etc., but is not limited thereto.

Further, the electrolyte includes any one or a combination of two or more of calcium chloride, potassium sulfate, sodium sulfate, potassium nitrate, sodium nitrate, potassium chloride, sodium chloride, glucose, and the like, but is not limited thereto.

Further, the time of the ultrasonic oscillation is below 10 h.

In some exemplary embodiments, the preparation method specifically includes: and mixing hydrofluoric acid and a hydroxide solution to prepare the fluoride solution, wherein the hydroxide solution comprises a potassium hydroxide solution and/or a sodium hydroxide solution and the like.

In some exemplary embodiments, the molar ratio of nickel salt to cobalt salt is y: 1, wherein y > 0, preferably 0 < y < 1.

In some exemplary embodiments, the cobalt salt includes, but is not limited to, cobalt sulfate (CoSO)₄) Cobalt chloride (CoCl)₂) Cobalt nitrate Co (NO)₃)₂And the like, or a combination of two or more thereof.

In some exemplary embodiments, the nickel salt includes, but is not limited to, nickel sulfate (NiSO)₄) Nickel chloride (NiCl)₂) Nickel nitrate (Ni)(NO₃)2) and the like, or a combination of two or more thereof.

In some exemplary embodiments, the preparation method further comprises: and after the reaction is finished, standing for layering, separating out solids, washing and drying to obtain the oxygen evolution electrocatalytic material based on the transition metal salt.

In some more specific exemplary embodiments, the method for preparing the transition metal salt-based oxygen evolution electrocatalytic material specifically comprises the following steps:

(1) taking 50mL of 3mol/L KF, and controlling the temperature of the solution to be minus 2 ℃ below zero to prevent metal ions from being hydrolyzed;

(2) in order to reach-2 ℃, a certain amount of electrolyte is added according to the colligative principle, so that the temperature of the solution can be reduced to-2 ℃; and then 0.05mol of cobalt salt is taken, a certain amount of Ni (II) salt is added into the cobalt salt, the molar ratio of Ni (II) to Co can be (0-1) to 1, and even the molar amount of Ni (II) can be more than that of Co. The XRD diffraction peak of the alloy is shifted according to the content of the added Ni (II);

(3) the electrolyte added according to the principle of colligative property includes, but is not limited to, calcium chloride, potassium sulfate, sodium sulfate, potassium nitrate, sodium nitrate, potassium chloride, sodium chloride, and even glucose and other substances with colligative property capable of reducing temperature;

(4) grinding cobalt salt and Ni (II) salt, directly adding into the KF solution, and ultrasonically stirring for 0.0-10.0 h; and then raising the temperature to 85-99 ℃, and continuing to react to obtain a product. Standing for layering, separating out solid, washing and drying to obtain the nickel-doped trifluoro cobaltate oxygen evolution electrocatalyst.

Another aspect of an embodiment of the present invention provides a transition metal salt-based oxygen evolution electrocatalytic material prepared by the foregoing method, which has a perovskite-type cubic crystal system crystal structure and a space group of P_m3_mSpace group with chemical formula of MCo_(1-x)Ni_xF₃M represents a charge-balancing ion, 0 < x < 1.

Further, M includes potassium ion, sodium ion, etc., but is not limited thereto.

Another aspect of an embodiment of the present invention provides an application of the transition metal salt-based oxygen evolution electrocatalytic material as an oxygen evolution electrocatalyst in hydrogen production by water electrolysis.

Accordingly, another aspect of the embodiments of the present invention also provides a method for producing hydrogen by electrolyzing water, which includes:

preparing the oxygen evolution electrocatalytic material based on the transition metal salt into a carbon paste electrode or a metal-based electrode;

with said transition metal salt based oxygen evolution electrocatalytic material (MCo)_(1-x)Ni_xF₃) The prepared carbon paste electrode or metal-based electrode is an oxygen evolution electrode, nickel is used as a hydrogen evolution electrode, and is matched with an alkaline aqueous solution to form a water electrolysis hydrogen production system, and the water electrolysis hydrogen production is realized by electrifying the oxygen evolution electrode and the hydrogen evolution electrode.

By the technical scheme, cobalt ions are used as central ions, a certain amount of nickel ions are doped, potassium ions or sodium ions are used as charge balance ions, fluorine ions are used as ligands, a novel electro-catalytic oxygen evolution material is generated through coordination reaction of the cobalt ions and the ligands in a solvent, the oxygen evolution overpotential of the oxygen evolution electro-catalytic material is obviously lower than that of an iridium electrode when the oxygen evolution material is applied to hydrogen production by water electrolysis, excellent oxygen evolution electro-catalytic performance and electro-catalytic stability are shown, and the novel electro-catalytic oxygen evolution material is expected to be widely applied to the field of new energy.

The technical solutions of the present invention will be described in further detail below with reference to several preferred embodiments and accompanying drawings, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. It is to be noted that the following examples are intended to facilitate the understanding of the present invention, and do not set forth any limitation thereto. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention. The experimental procedures, in which specific conditions are not noted in the following examples, are generally carried out under conventional conditions or conditions recommended by the manufacturers.

Comparative example 1

Potassium trifluoro cobaltate KCoF₃The preparation of (1): taking 3mol/LKF 50mL to preventMetal ions are hydrolyzed, and the temperature of the solution is controlled to be minus 2 ℃. In order to reach-2 ℃, solid NaCl is added to saturate according to the colligative principle; taking 0.05mol of cobalt salt, grinding, directly adding into the KF solution, and ultrasonically oscillating for 0.0-10.0 h; then keeping the heating rate at 1 ℃/min to 85 ℃, and continuing to react for 0.5 to 2 hours to obtain the product. Standing for layering, separating out solids, washing and drying to obtain the oxygen evolution electrocatalyst KCoF₃The X-ray powder diffraction spectrum is shown as curve a in figure 1 and is consistent with the diffraction pattern corresponding to the standard card number JCPDS 18-1006.

Comparative example 2

Similarly, potassium trifluoroacetate KNiF₃As comparative example 2, the diffraction pattern obtained is shown in FIG. 1 as curve b.

Comparative example 3

Taking 0.15mmol of KF or NH₄And F, taking 0.0375mol of cobalt chloride, then taking 0.0125mol of nickel chloride, grinding and mixing, putting into a tube furnace, heating to 350 ℃ under the protection of nitrogen airflow, keeping the temperature for 2-5 h, collecting the obtained product, and measuring XRD diffraction data of the product, wherein the diffraction pattern of the product is similar to the curve a in the figure 1.

Example 1

KCo_0.75Ni_0.25F₃The preparation of (1): taking 50mL of 3mol/L hydrofluoric acid, adding 55mL of 3mol/L KOH, introducing nitrogen, and deoxidizing for 20 minutes; then 0.0375mol of cobalt sulfate and 0.0125mol of nickel sulfate are taken, mixed and ground, and then directly added into the solution, and the temperature is kept at 95 ℃ under the ultrasonic oscillation condition, and the reaction is carried out for 1 hour, thus obtaining the product. Standing for layering, separating out solids, washing and drying to obtain the oxygen evolution electrocatalyst KCo_0.75Fe_0.25F₃The XRD diffractogram is shown as curve c in FIG. 1.

Example 2

KCo_0.5Ni_0.5F₃The preparation of (1): taking 50mL of 3mol/L KF, introducing nitrogen to remove oxygen for 25 minutes; in order to prevent the metal ions from hydrolysis, the temperature of the solution is controlled at-2 ℃. In order to reach-2 ℃, solid NaCl is added to saturate according to the colligative principle; grinding 0.025mol of cobalt chloride and 0.025mol of nickel sulfate, directly adding into the solution, and ultrasonically oscillating for 0.0-10.0 h; then the temperature is increased to 99 ℃, followed byThe reaction is continued for 0.5h to obtain the product. Standing for layering, separating out solids, washing and drying to obtain the oxygen evolution electrocatalyst KCo_0.5Ni_0.5F₃The XRD diffractogram is similar to curve c in FIG. 1.

Example 3

KCo_0.6Ni₀₄F₃The preparation of (1): taking 50mL of 3mol/L KF, introducing nitrogen to remove oxygen for 30 minutes; in order to prevent the metal ions from hydrolysis, the temperature of the solution is controlled at-2 ℃. In order to reach-2 ℃, solid NaCl is added to saturate according to the colligative principle; taking 0.03mol of cobalt nitrate and 0.02mol of nickel sulfate, grinding, directly adding into the solution, and ultrasonically oscillating for 0.0-10.0 h; then raising the temperature to 85 ℃, and continuing to react for 2h to obtain the product. Standing for layering, separating out solids, washing and drying to obtain the oxygen evolution electrocatalyst KCo_0.6Ni_0.4F₃The XRD diffractogram is similar to curve c in FIG. 1.

Hereinafter, the present inventors also compared KCoF of comparative example 1₃KFeF of comparative example 2₃And KCo obtained in example 1_0.75Fe_0.25F₃The characterization and the test of each performance are carried out, and the results are as follows:

first, in example 1 of the present invention, a certain amount of Ni (II) salt is added to cobalt salt, the molar ratio of Ni (II) to Co can be (0-1) to 1, even the molar amount of Ni (II) can be larger than that of Co. The XRD diffraction peak shifts according to the content of Ni (II) added. Please refer to fig. 1, which shows KCoF₃、KNiF₃And KCo_0.75Ni_0.25F₃XRD pattern of the sample. From the diffraction pattern, KCoF₃The diffraction peaks of the electrocatalyst at 2 theta 21.842 deg., 31.064 deg., 38.285 deg. correspond to KCoF₃(100), (110) and (111) indices of the crystal planes of (JCPDS18-1006), KNiF₃Diffraction peaks of the sample at 2 θ 22.143 °, 31.484 °, 38.806 ° correspond to KNiF, respectively₃The (100), (110) and (111) crystal plane indices (JCPDS 72-0112). Nickel doped fluoride KCo_0.75Ni_0.25F₃The diffraction angle and interplanar spacing at 2 theta 21.982 deg., 31.264 deg., 38.506 deg. are both between those of the monometallic fluoride KCoF₃And KNiF₃In between, showThe bimetal of Co and Ni changes the unit cell size.

Secondly, the inventors also compared KCoF of comparative example 1₃KNiF of comparative example 2₃And KCo obtained in example 1_0.75Ni_0.25F₃The results of transmission electron microscope tests show that KCo_0.75Ni_0.25F₃The morphology, diffraction spots and interplanar spacings of (A) are shown in FIGS. 2A-2C, KNiF₃The morphology, diffraction spots and interplanar spacing of (A) are shown in FIGS. 2D-2F, KCoF₃The morphology, diffraction spots and interplanar spacings of (a) are shown in FIGS. 2G-2I. The results of the surface spacing were consistent with those of the powder diffraction, further showing that the resulting product was a perovskite fluoride.

Third, the inventor of the present invention is on KCo_0.75Ni_0.25F₃EDX spectroscopy was performed as shown in fig. 3A and 3B. FIG. 3A shows that the synthesized sample contains four elements of K, Co, Ni and F (Cu comes from the carrier copper net). The elemental contents of the spectra were plotted to obtain FIG. 3B, in which the atomic percentage of Co was 14.43%, the atomic percentage of Ni was 3.53%, and the ratio of Co to Ni was 4.1: 1, indicating that Ni replaced some of the Co. The atomic percent of F was 63.37% and the atomic percent of K was 18.65%, again demonstrating the synthesis of KCo_0.75Ni_0.25F₃。

Fourthly, the inventors also compared KCoF of comparative example 1₃KNiF of comparative example 2₃And KCo obtained in example 1_0.75Ni_0.25F₃The inventor synthesizes a series of KCo by performing oxygen evolution performance tests_(1-x)Ni_xF₃Electrocatalyst, 0.15g KCo is weighed_(1-x)Ni_xF₃The linear scanning curve of the catalyst prepared into a carbon paste electrode in 1.0mol/LKOH is shown in FIG. 4, wherein curve a represents graphite, curve b represents KNiF₃Curve c represents KCo_0.5Ni_0.5F₃Curve d represents IrO₂Curve e represents KCoF₃Curve f represents KCo_0.25Ni_0.75F₃Curve g represents KCo_0.75Ni_0.25F₃。KCoF₃And nickel-doped IIIThe oxygen evolution overpotential of the potassium fluocobaltate is lower than that of the noble metal iridium. The oxygen evolution parameters for each electrode material at a current density of 30 milliamps per square centimeter are shown in table 1. KCo_(1-x)Ni_xF₃(x is less than 1.0) overpotential ratio of oxygen evolution of electrocatalyst₂Also has low cost, shows excellent oxygen evolution performance and can effectively reduce the energy consumption of the electrolyzed water.

TABLE 1 KCo_(1-x)NI_xF₃Electrochemical parameters

*η₃₀The current density is 30mV/cm²The overpotential of time.

Fifth, the present inventors also performed on the synthesized KCo_0.75Ni_0.25F₃The stability of the electrocatalyst was tested

For testing KCo_0.75Ni_0.25F₃The i-t curve of the electrode at 0.6V (vs. SCE) is shown in FIG. 5. The current of the electrolyzed water for 16 hours is 28mA/cm²The current density of the electrode is substantially unchanged at the end.

Example 4

Taking a series of KCo prepared by the invention_(1-x)Ni_xF₃0.15g of the raw materials are added into 0.45 g of graphite powder, the mixture is ground by a mortar, and a proper amount of silica gel oil is added and mixed evenly to obtain the carbon paste. Injecting carbon paste into 3mm diameter polytetrafluoroethylene tube, compacting, and forming KCo-containing copper wire_(1-x)Ni_xF₃A carbon paste electrode of an oxygen evolution electrocatalyst. The carbon paste electrode is used as an oxygen evolution electrocatalyst, the nickel foam is used as a hydrogen evolution electrode, water is electrolyzed in 1.0mol/LKOH alkaline solution under the bath pressure of 1.6 volts, oxygen can be observed to be separated out at the anode, and hydrogen can be observed to be separated out at the cathode.

In conclusion, the novel oxygen evolution electrocatalytic material based on the transition metal salt is generated by adopting cobalt ions as central ions, doping a certain amount of nickel ions, adopting potassium ions or sodium ions as charge balance ions and adopting fluorine ions as ligands through the coordination reaction of the cobalt ions and the ligands in a solvent, and the nickel doped oxygen evolution material has more excellent oxygen evolution performance and stable electrocatalytic performance.

It should be understood that the above-mentioned embodiments are merely illustrative of the technical concepts and features of the present invention, which are intended to enable those skilled in the art to understand the contents of the present invention and implement the present invention, and therefore, the protection scope of the present invention is not limited thereby. All equivalent changes and modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.