KR102201079B1 - The method of generating oxygen vacancies in nickel-iron oxide catalyst for oxygen evolution reaction and the nickel-iron oxide catalyst manufactured thereby - Google Patents

Abstract

The present invention synthesizes nickel-iron oxide having good activity as an electrochemical catalyst using a hydrothermal synthesis method, and then performs a partial reduction reaction in a mixed gas atmosphere in which hydrogen and argon gas are mixed at a certain ratio to A method for producing a nickel-iron oxide catalyst in which oxygen depletion occurs to enhance the activity of an oxygen evolution reaction, and a nickel-iron oxide catalyst according to the method are provided.
According to the present invention, oxygen deficiency can be generated even at a low temperature, and in this other method, the synthesized nickel-iron oxide with oxygen-deficiency defects is more capable of adsorbing hydroxyl groups on the catalyst surface than the conventional nickel-iron oxide. As a result, the electrochemical activity increases, and it is useful as a catalyst for oxygen reduction.

Description

The method of generating oxygen vacancies in nickel-iron oxide catalyst for oxygen evolution reaction and the nickel-iron oxide catalyst manufactured thereby}

The present invention relates to a method for inducing oxygen starvation in a nickel-iron oxide structure for generating oxygen, and more particularly, to generate oxygen starvation inside or on the surface of nickel-iron oxide by performing a partial reduction reaction of the nickel-iron oxide structure. Thus, the present invention relates to a method for producing a catalyst having a high oxygen generation activity, and a nickel-iron oxide catalyst thereby.

Recently, fossil fuel resource depletion and environmental pollution are serious, and many studies in energy related fields are being conducted to solve this problem. Among them, metal-air cells, fuel cells, and water electrolyzers are attracting attention as future energy devices due to their various advantages. The common point of the above energy devices is that they include a series of processes of reducing or generating oxygen molecules. Since the process of generating such reduction is a sluggish reaction requiring a high voltage, an efficient catalyst is required.

On the other hand, hydrogen energy attracts the most attention in that it uses water, the most abundant material on the planet, as a raw material, is a clean energy source that does not generate pollutants during hydrogen combustion, and also functions as an energy storage medium. Hydrogen can itself be a clean fuel as described above, and is required in many chemical reactions and processes.

In addition, in recent years, hydrogen energy is more needed as a clean fuel. Hydrogen energy is an energy source that is in the spotlight as the next-generation energy because it is environmentally friendly and there is no limit in the amount of mining and local ubiquity. Among them, the hydrogen station method, which directly generates and supplies hydrogen by electrolyzing water, provides the advantage of producing high-purity hydrogen without environmental damage.

The electrolysis reaction of water can be divided into a hydrogen evolution reaction (HER) reaction that occurs in a reduction electrode and an oxygen evolution reaction (OER) that occurs in an oxidation electrode.

-Reduction electrode _{(cathode): 4H 2 O +} 4e - → 2H 2 + 4OH -

- oxidation electrode ^{(anode): 4OH - → O} 2 + 2H 2 O + 4e -

The oxygen evolution reaction that takes place at the anode is the step that determines the most important rate for hydrogen evolution among the total electrolysis reaction. This is because the oxygen evolution reaction (OER) requires energy to break O-H bonds and form O-O bonds, so the rate is much slower compared to the hydrogen evolution reaction at the cathode. For this reason, there is a problem in that a high additional voltage (overvoltage) and energy must be injected in oxygen generation.

Ruthenium (Ru), which is most widely known as such an electrode material for generating oxygen, is expensive and has a problem in that it elutes because it is vulnerable to an acidic atmosphere, and studies to replace it with a low-cost transition metal oxide catalyst are actively being conducted. In general, metal oxides based on transition metals have various oxidation values and are very advantageous for redox reactions and are used as catalyst materials for energy conversion reactions.

Among the transition metals, spinel-type oxides composed of two metals exhibit high activity in electrochemical reactions, and the initiation potential through various synthesis methods and doping to synthesize them, and formation of a complex with carbon materials. Attempts to develop a cathode catalyst having a higher activity by lowering and increasing the current density are being conducted.

Korean Patent Registration No. 10-1774154 (announcement date: 2017.09.13) discloses a method of preparing an oxygen generation or oxygen reduction catalyst containing a spinel crystalline material and a perovskite crystalline material in which oxygen deficiency exists, Korean Patent Publication No. 10-2018-0012468 (published date: 2018.02.06.) describes a technology for preparing a catalyst for oxygen generation reaction including a metal oxide nanostructure doped by a transition metal cation.

However, despite the attempts of various types of methods for preparing electrochemical catalysts in the prior art including the prior art, the need for the development of more improved catalysts for generating oxygen is continuously required.

Korean Patent Registration No. 10-1774154 (announcement date: 2017.09.13.) Korean Patent Publication No. 10-2018-0012468 (Publication date: 2018.02.06.)

The main object of the present invention is to solve the above-described problems, by performing a partial reduction reaction in a mixed gas atmosphere including a certain ratio of hydrogen gas in nickel-iron oxide, and oxygen atom depletion inside or on the surface of nickel-iron oxide. It is to provide a method for producing a catalyst having improved oxygen generation reaction activity by generating and a catalyst thereby.

In order to achieve the above technical problem, an embodiment of the present invention, (a) dissolving a nickel precursor and an iron precursor in distilled water to prepare an aqueous precursor solution; (b) adding a basic solution to the precursor solution to adjust the pH to prepare a basic aqueous precursor solution; (c) hydrothermal synthesis of the basic aqueous precursor solution; (d) washing and drying the resultant product synthesized by the hydrothermal synthesis method; (e) generating oxygen deficiency in the nickel-iron oxide by performing a partial reduction reaction under a mixed gas atmosphere of hydrogen (H ₂ ) gas and an inert gas; and, step (e) includes 8 to 15 vol It provides a method for producing a catalyst for generating oxygen, characterized in that performing a partial reduction reaction at a temperature range of 80 ~ 150 ℃ in a mixed gas atmosphere containing% of hydrogen (H ₂ ) gas.

In a preferred embodiment of the present invention, the nickel precursor in step (a) is nickel (II) nitrate hexahydrate, nickel (II) chloride hexahydrate (Nickel Chloride Hexahydrate), nickel (II) acetate It may be at least one selected from the group consisting of tetrahydrate (Nickel Acetate Tetrahydrate) and nickel (II) bromide hydrate (Nickel Bromide Hydrate).

In a preferred embodiment of the present invention, the iron precursor in step (a) is iron (III) nitrate nonahydrate, iron (III) chloride hexahydrate (Iron Chloride Hexahydrate), iron (II) acetate It may be one or more selected from the group consisting of tetrahydrate (Iron Acetate Tetrahydrate) and iron (II) bromide hydrate (Iron bromide Hydrate).

In a preferred embodiment of the present invention, the basic material in the basic solution in step (b) is potassium hydroxide (KOH), sodium hydroxide (NaOH), calcium hydroxide (Ca(OH) ₂ ), barium hydroxide (Ba(OH) ₂ ) It may be one or a mixture of one or more selected from ammonium hydroxide (NH ₄ OH).

In a preferred embodiment of the present invention, the pH range in step (b) may be 12 to 14.

In a preferred embodiment of the present invention, the temperature for hydrothermal synthesis in step (c) may be 100 to 250°C.

In a preferred embodiment of the present invention, the inert gas in step (e) may be argon gas.

In addition, in another embodiment of the present invention, the present invention provides a catalyst for generating oxygen including nickel-iron oxide prepared by any one of the above methods and having oxygen deficiency on the surface.

In addition, in another embodiment of the present invention, the present invention provides an electrochemical water decomposition apparatus including the catalyst for generating oxygen.

If the partial reduction reaction is performed according to the partial reduction reaction conditions of the present invention, the partial reduction reaction proceeds easily even at a low temperature, and the nickel-iron oxide catalyst produced through the partial reduction reaction has high electrical conductivity and a lower initiation potential and It shows a high current density and shows high activity as a catalyst for oxygen evolution.

1 is a photograph of a nickel-iron oxide having a spinel structure prepared according to Example 1 and Comparative Examples 1 to 4 according to the present invention as an X-ray diffraction pattern (XRD).
FIG. 2 is a photograph of a nickel-iron oxide having a spinel structure prepared according to Example 1 and Comparative Examples 1 to 4 according to the present invention, observed with an X-ray diffraction pattern (XRD) magnified at a specific angle.
3 is a photograph showing a result of a photoelectron analyzer (XPS) of nickel-iron oxide having a spinel structure prepared according to Example 1 and Comparative Examples 1 to 4 according to the present invention.
4 is a graph showing the results of a linear scanning voltage method of nickel-iron oxide having a spinel structure prepared according to Example 1 and Comparative Examples 1 to 4 according to the present invention.
5 is a graph showing a current density plot result according to a scanning speed of a spinel structure of nickel-iron oxide prepared according to Example 1 and Comparative Examples 1 to 4 according to the present invention.
6 is a graph showing the results of the linear scanning voltage method of nickel-iron oxide having a spinel structure prepared according to Example 1 and Comparative Examples 6 to 7 according to the present invention.

Hereinafter, with reference to the accompanying drawings, to describe in detail a preferred embodiment of a method for producing a catalyst for oxygen evolution according to the present invention so that those skilled in the art can easily carry out the present invention. do.

In describing the principles of the preferred embodiments of the present invention in detail, when it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

In addition, the embodiments described in the present specification and the configurations shown in the drawings are only the most preferred embodiment of the present invention, and do not represent all the technical spirit of the present invention, so various alternatives that can be replaced at the time of application It should be understood that there may be equivalents and variations.

The present invention relates to a method for producing a catalyst for oxygen generation reaction that exhibits more excellent electrical activity with lower overvoltage and higher limiting current density than conventional nickel-iron oxide through partial reduction reaction in a mixed gas atmosphere containing hydrogen gas and inert gas. Specifically, (a) dissolving a nickel precursor and an iron precursor in distilled water to prepare an aqueous precursor solution; (b) adding a basic solution to the precursor solution to adjust the pH to prepare a basic aqueous precursor solution; (c) hydrothermal synthesis of the basic aqueous precursor solution; (d) washing and drying the resultant product synthesized by the hydrothermal synthesis method; (e) generating oxygen deficiency in the nickel-iron oxide by performing a partial reduction reaction under a mixed gas atmosphere of hydrogen (H ₂ ) gas and an inert gas; and, step (e) includes 8 to 15 vol It provides a method for producing a catalyst for generating oxygen, characterized in that performing a partial reduction reaction at a temperature range of 80 ~ 150 ℃ in a mixed gas atmosphere containing% of hydrogen (H ₂ ) gas.

Hereinafter, a method for producing a nickel-iron oxide having oxygen deficiency according to the present invention will be described in detail for each step.

To explain step (a), first, a nickel precursor and an iron precursor are dissolved in distilled water in an appropriate ratio, for example, 1:2 to prepare an aqueous precursor solution.

As the nickel precursor, the nickel compound is nickel (II) nitrate hexahydrate, nickel (II) chloride hexahydrate, nickel (II) acetate tetrahydrate (Nickel Acetate Tetrahydrate) and nickel (II) ) It is preferably at least one selected from the group consisting of bromide hydrate, and it is more preferable to use nickel (II) chloride hexahydrate, but the scope of the present invention is not limited thereto. .

Iron (III) nitrate nonahydrate (Iron Nitrate Nonahydrate), iron (III) chloride hexahydrate (Iron Chloride Hexahydrate), iron (II) acetate tetrahydrate (Iron Acetate Tetrahydrate) and iron (II) as the iron precursor iron compound ) It is preferably at least one selected from the group consisting of bromide hydrate, and it is more preferable to use iron (III) chloride hexahydrate, but the scope of the present invention is not limited thereto. .

Subsequently, step (b) is a step of preparing a basic aqueous precursor solution by adding a basic solution to the aqueous precursor solution prepared in step (a) to adjust the pH of the aqueous precursor solution.

To describe the steps (a) and (b) in more detail, first, an aqueous precursor solution is prepared by dissolving a nickel precursor and an iron precursor in distilled water. Then, a basic aqueous solution in which a basic substance is dissolved in distilled water is added to the precursor aqueous solution to adjust the pH of the precursor aqueous solution. At this time, the pH must be adjusted until the color of the reactant formed by precipitation turns blue. After that, the solution in which the blue reactant has precipitated is dispersed by vigorous stirring for 2 hours or more so that it can be well dispersed and synthesized. At this time, the pH range is preferably 12 to 14.

The basic material in the basic solution in step (b) is not particularly limited, and may be selected from organic and inorganic basic materials. The basic material is one or more mixtures selected from potassium hydroxide (KOH), sodium hydroxide (NaOH), calcium hydroxide (Ca(OH) ₂ ), barium hydroxide (Ba(OH) ₂ ) and ammonium hydroxide (NH ₄ OH) It may be used, but is not limited thereto. These basic substances are added to the precursor solution in an aqueous solution to adjust the pH of the precursor solution.

In addition, the step (c) is a step of hydrothermally synthesizing the basic aqueous precursor solution prepared in step (b), and specifically, the basic aqueous precursor solution is put into an autoclave to 100 to 250° C., preferably 150 The reaction is performed at ~ 250° C. for 4 hours to 24 hours, preferably for 8 to 16 hours. Such control of temperature and time prevents the agglomeration of particles and induces the synthesis to be evenly dispersed. After the reaction time has ended, remove the autoclave from the oven and let it cool to its natural state.

Subsequently, step (d) is a process of washing and drying the resultant product synthesized in step (c). The result of hydrothermal synthesis in step (c) is a process for removing impurities such as sodium and chlorine because impurities such as sodium and chlorine are mixed. Specifically, centrifugation is performed 5 times at 8000 rpm using distilled water. After centrifugation, the precipitated product is dried at 60° C. for preferably 12 to 24 hours, more preferably 20 to 24 hours to obtain nickel-iron oxide in a state in which impurities are removed.

In addition, the step (e) is a step of generating oxygen deficiency through a partial reduction reaction in order to increase the activity of the nickel-iron oxide obtained in step (d) as an electrochemical catalyst.

Specifically, first, an inert gas is flowed into the tube furnace for 20 to 40 minutes to saturate the inside of the furnace with an inert gas, thereby making it a state in which no additional reaction occurs. Then, the temperature is raised to the target temperature to be changed, and the temperature is raised at a rate of 5 to 20 ℃/min. When the temperature rises to the target, hydrogen (H ₂ ) gas is mixed with an inert gas in a certain volume ratio and flowed to perform a partial reduction reaction to create oxygen deficiency on the inside or surface of the nickel-iron oxide structure. .

In addition, in step (e), the hydrogen (H ₂ ) gas in the mixed gas is preferably added in an amount of 8 to 15 vol% based on the total mixed gas. When the hydrogen (H ₂ ) gas exceeds 15 vol% of the total mixed gas, the amount of oxygen depletion may be excessively formed, resulting in a decrease in electrochemical activity due to the formation of amorphous and the collapse of the lattice, and hydrogen (H ₂ ) When the gas is added in less than 8 vol% of the total gas mixture, it requires a lot of energy to introduce oxygen deficiency inside or on the surface of nickel-iron oxide.

In addition, the partial reduction temperature in step (e) is preferably in the range of 80 to 150° C. in terms of effectively generating oxygen deficiency on the inside or the surface of the nickel-iron oxide structure.

When the partial reduction temperature is less than 80°C, the energy to break the bond between the metal atom and the oxygen atom in the nickel-iron oxide is insufficient, and the generation of oxygen deficiency inside or on the nickel-iron oxide is insufficient, and the partial reduction temperature is When it exceeds 150° C., there is a possibility that the phase of the material of some or all of the nickel-iron oxide generated by oxygen deficiency through partial reduction is changed to nickel metal, and the electrochemical activity of the nickel-iron oxide structure is lost.

During the partial reduction reaction in step (e), the temperature and gas atmosphere inside the tube furnace are always kept constant, and the partial reduction reaction is preferably performed for 2 to 10 hours.

In addition, the present invention provides a catalyst for an oxygen evolution reaction comprising a nickel-iron oxide prepared by any one of the above methods and having oxygen deficiency on the surface.

In addition, the present invention provides an electrochemical water decomposition apparatus including the catalyst for oxygen generation reaction.

The present invention as described above is described in detail based on the following examples, and the present invention is not limited by the following examples.

Hereinafter, the present invention will be described in more detail with reference to preferred embodiments. However, these examples are for explaining the present invention in more detail, and it will be apparent to those of ordinary skill in the art that the scope of the present invention is not limited thereto.

Example 1

Step (a): 0.3 g of NiCl _{2 and} 0.6 g of FeCl ₃ were quantified in 60 ml distilled water, put into a beaker, and stirred for about 30 minutes to prepare a precursor solution.

Step (b): A 1 M sodium hydroxide solution is prepared, 15 ml of 1 M sodium hydroxide is mixed with the precursor solution prepared in step (a), followed by stirring to prepare a basic precursor solution.

Step (c): The basic precursor solution prepared in step (b) is put into an autoclave and heated at 200° C. for 12 hours to react.

Step (d): After filtering the resultant obtained in step (c), a washing process is performed using a centrifuge to obtain powder.

Step (e): Put the washing product obtained in step (d) into a tube furnace and perform partial reduction reaction at 100°C for about 5 hours to obtain a spinel structure nickel-iron oxide having oxygen defects. Was prepared. At this time, the rate of heating up to the target temperature was 10°C/min, and the mixing ratio of hydrogen gas and argon gas during the partial reduction reaction was maintained at 1:9.

Comparative Example 1

It is the same as in Example 1, except that the partial reduction reaction was performed at 200°C in step (e) of Example 1 above.

Comparative Example 2

It is the same as in Example 1, except that the partial reduction reaction was performed at 300°C in step (e) of Example 1 above.

Comparative Example 3

It is the same as in Example 1, except that the partial reduction reaction was performed at a temperature of 50 °C in step (e) of Example 1 above.

Comparative Example 4

It is the same as Example 1, except that the partial reduction reaction of step (e) of Example 1 was not performed.

Comparative Example 5

It is the same as in Example 1, except that in step (e) of Example 1, a partial reduction reaction was performed in an air atmosphere instead of a mixed gas atmosphere of hydrogen and argon gas.

Comparative Example 6

It is the same as in Example 1, except that in step (e) of Example 1, the volume ratio of hydrogen and argon gas was injected at 5:95.

Comparative Example 7

It is the same as in Example 1, except that in step (e) of Example 1, a volume ratio of hydrogen and argon gas was injected at a volume ratio of 2:8.

In addition, the partial reduction conditions in Comparative Examples 1 to 3, Comparative Examples 5 to 7, and Example 1 are summarized and shown in Table 1 below.

Partial reduction condition Hydrogen: argon ratio Temperature(℃) Example 1 10: 90 100 Comparative Example 1 10: 90 200 Comparative Example 2 10: 90 300 Comparative Example 3 10: 90 50 Comparative Example 5 Air atmosphere 100 Comparative Example 6 5: 95 100 Comparative Example 7 20: 80 100

Experimental Example 1. X-ray diffraction analysis of spinel structure oxide

In order to examine the characteristics of the spinel structure oxides prepared according to Example 1 and Comparative Examples 1 to 4, an X-ray diffraction analyzer (Rigaku, Mini flex) was used to analyze the results, and the results are shown in FIGS. 1 and 2.

1 shows an X-ray diffraction pattern (XRD) of the spinel structure oxides prepared in Example 1 and Comparative Examples 1 to 4 above. Referring to FIG. 1, it can be seen that a spinel structure oxide peak appears in both Example 1 and Comparative Examples 1 to 4. This means that the produced spinel structure maintains the spinel structure without changing the crystal structure even after additional heat treatment in a hydrogen atmosphere.

FIG. 2 shows an X-ray diffraction pattern (XRD) of the spinel structure oxides prepared in Example 1 and Comparative Examples 1 to 4 in an enlarged range from 32 to 39 degrees from the result of FIG. 1. 2, it can be seen that the peak of the spinel structure oxide prepared in Example 1 shifted. This indicates that the spinel structure contracted due to structural defects.

Experimental Example 2. Analysis of oxidation state of spinel structure oxide

In order to investigate the oxidation state of the spinel structure oxides prepared according to Example 1 and Comparative Examples 1 to 4, it was analyzed using an X-ray photoelectron spectroscopy (SPECS, EA200). The results are shown in FIG. 3.

3 shows the oxygen spectrum of the spinel structure oxides prepared according to Example 1 and Comparative Examples 1 to 4, respectively. According to Figure 3, the oxygen peak (peak) is separated into a total of four bonds, from a low section, the bond between the oxygen element and the metal element (O _M ), the bond of the hydroxyl group inside the oxygen element (O _OH ), oxygen deficiency ( It is divided into a peak due to O _V ) and chemical bonding with moisture in the air (O _C ). At this time, in Example 1 according to the present invention, as the area ratio of the peak due to oxygen deficiency (O _V ) increases, it can be seen that oxygen depletion occurs through partial reduction. The values were measured and shown in Table 2.

O _M O _OH O _V O _C Example 1 37.9 36.7 17.1 8.3 Comparative Example 1 51.1 25.4 16.5 7 Comparative Example 2 45.8 31.8 16.2 6.2 Comparative Example 3 57.8 27.4 8.9 5.9 Comparative Example 4 59.9 27.8 8.3 4 Comparative Example 5 45.5 28.5 16.1 9.9 Comparative Example 6 35.5 33.7 16.6 14.2 Comparative Example 7 52.6 22.1 20.5 4.8

As shown in Table 2, when comparing the area ratio of the peak due to oxygen deficiency (O _V ) in the oxygen peaks of Example 1 and Comparative Examples 6 and 7, it was found that the higher the ratio of hydrogen, the greater the amount of oxygen deficiency. I can confirm.

In comparison between Example 1 and Comparative Examples 1 to 3, in Comparative Example 3 having a partial reduction reaction temperature of 50°C, oxygen deficiency did not occur very much, and the reaction temperature was maximum at 100°C and 200°C or 300°C. It can be seen that the amount of oxygen deficiency is rather reduced when is increased.

Experimental Example 3. Electrochemical Activity Analysis of Spinel Structure Oxide

In order to compare and analyze the performance of the spinel structure oxides prepared according to Example 1 and Comparative Examples 1 to 7 as an electrode catalyst for oxygen generation reaction, the following experiment was conducted.

In order to investigate the electrochemical properties of the spinel structure oxides prepared according to Example 1 and Comparative Examples 1 to 7, 5 mV/s in 1 mol of KOH electrolyte using a potentiostat (Princeton Applied Research, VSP). The linear voltammetry was analyzed at the scanning speed of. The results are shown in FIG. 4. The high measured current density means that the electrochemical reaction is active, and thus the activity of the oxygen generating reaction is high.

As shown in FIG. 4, the spinel structure oxide of Example 1 of the present invention exhibits the highest current density per unit area, and thus, when used as an electrode catalyst material for oxygen generation reaction, it is higher than that of the spinel structure oxide with less oxygen defects. It was found that it has electrochemical activity.

비교예 7

비교예 6 > 비교예 2 > 비교예 3

비교예 4 의 순으로 나타나고 있어, 산소 결핍의 정도의 순인 비교예 7 > 실시예 1 > 비교예 6

비교예 1 > 비교예 2

비교예 5 > 비교예 3 > 비교예 4와 대비하여 보면, 대체적으로 산소 결핍의 정도가 클수록 한계전류밀도 역시 증가되기는 하나, 완전히 일치하지는 않음을 알 수 있다.The order of the limiting current density is shown in Fig. 4, Example 1> Comparative Example 1> Comparative Example 5

Comparative Example 7

Comparative Example 6> Comparative Example 2> Comparative Example 3

It is shown in the order of Comparative Example 4, in order of the degree of oxygen deficiency Comparative Example 7> Example 1> Comparative Example 6

Comparative Example 1> Comparative Example 2

Comparative Example 5> Comparative Example 3> Compared with Comparative Example 4, it can be seen that although the limiting current density also increases as the degree of oxygen deficiency increases, it is not completely consistent.

In the case of Comparative Example 2, the oxygen deficiency was greater than that of Comparative Example 5, but the limiting current density was lower. In particular, the limiting current density was not higher than that of Comparative Example 1 even though Comparative Example 7 had the largest oxygen deficiency value.

From this, it can be seen that in addition to the factor of oxygen deficiency, other factors affect the limiting current density.

Experimental Example 4. Evaluation of electrochemical area through cyclic voltammetry

In order to compare and analyze the performance of the spinel structure oxides prepared according to Example 1 and Comparative Examples 1 to 4 as an electrode catalyst for oxygen generation reaction, the following experiment was conducted.

In order to examine the electrochemical properties of the spinel-structured oxides prepared in Example 1 and Comparative Examples 1 to 4, 10, 20, in 1 mol of KOH electrolyte using a potentiostat (Princeton Applied Research, VSP). Graphs were obtained through cyclic voltammetry at scan rates of 30, 40, 50, 60, 70, 80, 90 and 100 mV/s, and then plotted for the current density at 0.95 V at each scan rate. The results are shown in FIG. 5.

5, it was confirmed that the spinel structure oxide of Example 1 of the present invention had the highest double-layer capacitance in a linear plot. The significantly high capacitance of Example 1 indicates a high electrochemical surface area and a high surface roughness. When the electrochemical surface area is high, it indicates that the catalyst is easy for the electrochemical reaction, and thus the value of Example 1 shows the highest double-layer capacitance, which is consistent with the result of the limiting current density.

As the specific parts of the present invention have been described in detail above, it will be apparent to those of ordinary skill in the art that these specific descriptions are only preferred embodiments, and the scope of the present invention is not limited thereby. will be. Accordingly, it will be said that the substantial scope of the present invention is defined by the appended claims and their equivalents.

Claims (8)

In the production method of the catalyst for oxygen evolution,
(a) dissolving nickel (II) chloride (NiCl ₂ ) and iron (III) chloride (FeCl ₃ ) in distilled water to prepare an aqueous precursor solution;
(b) adding a basic solution to the precursor solution until a blue precipitate is obtained to prepare an aqueous basic precursor solution to adjust the pH in the range of 12 to 14;
(c) hydrothermal synthesis of the basic aqueous precursor solution at a temperature of 150 to 250°C;
(d) washing and drying the resultant product synthesized by the hydrothermal synthesis method;
(e) performing a partial reduction reaction in a mixed gas atmosphere of hydrogen (H ₂ ) gas and an inert gas to generate oxygen deficiency in the nickel-iron oxide; and,
In the step (e), by performing a partial reduction reaction for 2 to 10 hours at a temperature range of 80 to 150° C. in a mixed gas atmosphere containing 8 to 15 vol% of hydrogen (H ₂ ) gas, oxygen as a catalyst for generating oxygen A method for producing a catalyst for oxygen evolution, characterized in that to obtain a nickel-iron oxide having a spinel structure having a defect. delete delete The method of claim 1,
The basic substances in the basic solution in the step (b) are potassium hydroxide (KOH), sodium hydroxide (NaOH), calcium hydroxide (Ca(OH) ₂ ), barium hydroxide (Ba(OH) ₂ ) and ammonium hydroxide (NH ₄ OH). ). Method for producing a catalyst for oxygen evolution, characterized in that one or a mixture of one or more selected from. delete delete The method of claim 1,
In the step (e), the inert gas is argon gas. delete

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