CN117303515A - Barium-modified iron oxyhydroxide and preparation method and application thereof - Google Patents

Abstract

The invention is suitable for the technical field of electrocatalytic water splitting, and provides a barium-modified iron oxyhydroxide, and a preparation method and application thereof, wherein the preparation method comprises the following steps: and growing a barium-modified iron oxyhydroxide nano-sheet array on the metal foam substrate with the porous structure by a hydrothermal method. The preparation method comprises the specific steps of placing metal foam with large specific surface area into a polytetrafluoroethylene reaction kettle, adding the metal foam into a mixed solution containing urea, ammonium fluoride, ferric salt and barium salt, and performing hydrothermal reaction to obtain the barium-modified iron oxyhydroxide nano-sheet array. The barium-modified iron oxyhydroxide nano-sheet array is grown on the metal foam substrate by using a one-step hydrothermal method, and the method is simple and efficient; and the barium-modified iron oxyhydroxide nano-sheet array is used as a neutral water oxidation electrode, has rich active sites and unique electronic structures, and shows excellent neutral electrolyzed water catalytic activity and stability.

Description

A barium-modified iron oxyhydroxide and its preparation method and application

Technical field

The invention belongs to the technical field of electrocatalytic water splitting, and in particular relates to a barium-modified iron oxyhydroxide and its preparation method and application.

Background technique

Hydrogen is considered a new energy carrier that can be used to solve the energy crisis and reduce dependence on fossil energy due to its high energy density and zero-carbon combustion products. Currently, most industries use natural gas steam reforming and carbon vaporization reactions to produce hydrogen. During the process, a large amount of greenhouse gases such as CO ₂ are released, thereby exacerbating the greenhouse effect. The electrolysis of water hydrogen production technology can not only prepare high-purity hydrogen, but also directly use electricity generated by renewable energy sources. In recent years, people have been committed to developing high-performance non-precious metal catalysts to improve the efficiency of electrolyzers while controlling production costs, and have made good progress. However, whether it is an acidic electrolyzer based on proton exchange membrane or an alkaline electrolyzer based on anion exchange membrane, it is necessary to use a highly corrosive electrolyte, which not only causes great pollution to the environment, but also causes serious damage to the electrolyzer. . Therefore, the development of water splitting catalysts that can work efficiently under mild conditions is of great significance to the field of hydrogen production from water electrolysis. However, current progress in the field of neutral electrolysis of water is slow. This is mainly due to the low concentration of intermediate reactants in water splitting in a neutral environment, which is not conducive to the adsorption/activation of the reactants by the catalyst. Therefore, rationally designing catalyst components and regulating the electronic structure of the catalyst so that it can be efficiently used in neutral water splitting technology will provide assistance for the large-scale application of electrolyzed water.

The water splitting process consists of two half-reactions: the hydrogen evolution reaction (HER) involving the transfer of two electrons and the oxygen evolution reaction (OER) involving the transfer of four electrons. Since the latter involves more electron transfers, it has a higher reaction energy barrier and is a slower kinetic process. Therefore, the development of efficient catalysts for OER will greatly promote the development of the field of water splitting. In the existing technology, some precious metal catalysts such as iridium oxide (IrO ₂ ) and ruthenium oxide (RuO ₂ ) have achieved good results in neutral OER research. However, the earth's reserves of precious metal elements are low and the cost is high, which is not conducive to electrolysis. Large-scale application of water technology. Therefore, some non-noble metal catalysts, including cobalt-based, nickel-based and manganese-based, have also been proposed and used in pH-neutral OER. However, these catalysts have high overpotential (overpotential at a current density of 10mA/ ^cm2 is higher than 350mV) and poor stability (less than 150 hours), which is still far away from practical applications. Among non-precious metal catalysts, iron-based catalysts are considered to be materials with OER activity comparable to noble metals. However, iron-based catalysts tend to precipitate during the neutral water splitting reaction, resulting in extremely poor stability. This is because the catalyst is resistant to neutral water. Poor adsorption of water decomposition intermediates in the environment causes iron to be easily oxidized into high-valence iron salts, which are then dissolved into the electrolyte. On the other hand, alkaline earth metal elements are usually used to adjust the material's adsorption of small molecules and enhance the hydrophilicity of the material. Therefore, modifying iron-based catalysts with alkaline earth metals to effectively adjust the electronic structure and surface physical and chemical properties of the catalyst is expected to significantly improve the neutral water electrolysis activity of iron-based catalysts and promote the development of neutral water electrolysis anode catalysts.

Contents of the invention

The purpose of the present invention is to provide a barium-modified iron oxyhydroxide and its preparation method and application, aiming to solve the problems raised in the above background technology.

In order to achieve the above objects, the present invention provides the following technical solutions:

A method for preparing barium-modified iron oxyhydroxide, which uses a hydrothermal method to synthesize a barium-modified iron oxyhydroxide nanosheet array grown on a metal foam substrate. In the barium-modified iron oxyhydroxide nanosheet array, iron The atomic content is 10.59-29.33%, and the barium atomic content is 0.86-3.78%.

Further, the specific steps are: place the metal foam in a polytetrafluoroethylene reactor, add urea, ammonium fluoride, iron salt, barium salt and deionized water respectively, and use hydrothermal method to react, and the hydrothermal temperature is 100 -180°C, the hydrothermal time is 4-24 hours. After the reaction is completed, cool to room temperature, take it out, wash it and dry it in an oven to obtain a barium-modified iron oxyhydroxide nanosheet array grown on the metal foam.

Further, the thickness of the barium-modified iron oxyhydroxide nanosheet array is 5-70 nm.

Further, the metal foam is any one of nickel foam, iron foam, nickel-iron foam and copper foam.

Further, the concentration of urea is 0.017-0.167mol/L, and the concentration of ammonium fluoride is 0.083-0.333mol/L.

Further, the iron salt is any one of Fe(NO ₃ ) ₃ , Fe ₂ (SO ₄ ) ₃ and FeCl ₃ , and the concentration of the iron salt is 0.008-0.100 mol/L.

Further, the barium salt is Ba(NO ₃ ) ₂ or BaCl ₂ , and the concentration of the barium salt is 0.008-0.100 mol/L.

A barium-modified iron oxyhydroxide nanosheet array prepared according to the method.

Application of a barium-modified iron oxyhydroxide in electrocatalytic water oxidation reaction.

Further, the specific application method is: placing the barium-modified iron oxyhydroxide nanosheet array in a neutral electrolyte as an oxygen evolution electrode for neutral water oxidation reaction; the neutral electrolyte is phosphate buffer, in The concentration of electrolytes is 1mol/L.

Compared with the prior art, the beneficial effects of the present invention are:

1. The present invention develops a one-step hydrothermal method, introducing the alkaline earth metal barium element during the growth process of iron oxyhydroxide to form an array of barium-modified iron oxyhydroxide nanosheets. The preparation method is simple and efficient; the nanometers grown on the metal foam substrate The chip array can fully expose the active sites. At the same time, the modification of barium is conducive to enhancing the conductivity of iron oxyhydroxide, improving the electron transfer ability, thus promoting the reaction kinetics of the oxygen evolution reaction, and ultimately significantly improving the neutral water oxidation of the electrode. performance.

2. The present invention uses the barium-modified iron oxyhydroxide nanosheet array as a neutral water oxidation electrode, which exhibits excellent catalytic activity and stability. At current densities of 10 and 300 mA/ ^cm , the required OER overpotentials in neutral aqueous solution are as low as 268 and 578 mV, which are much lower than the individual iron oxyhydroxide nanosheet array samples. At the same time, the catalyst can operate for 200 and 50 hours at constant current densities of 10 and 300 mA/ ^cm , respectively, without significant degradation in water oxidation performance. This performance is superior to most non-precious metal catalysts in the existing technology.

Description of the drawings

Figure 1 shows scanning electron microscope (SEM) images at different magnifications of a barium-modified iron oxyhydroxide (denoted as Ba-FeOOH) nanosheet array grown on a nickel foam substrate after hydrothermal reaction.

Figure 2 shows scanning electron microscope (SEM) images at different magnifications of an iron oxyhydroxide (denoted as FeOOH) nanosheet array grown on a nickel foam substrate after hydrothermal reaction.

Figure 3 is a transmission electron microscope (TEM) image energy dispersive spectrum (EDS) element distribution diagram of Fe, Ba and O elements of Ba-FeOOH.

In Figure 4, (a) is the X-ray diffraction pattern (XRD) of FeOOH and Ba-FeOOH; (b) is the Raman spectrum (Raman) comparison chart of FeOOH and Ba-FeOOH; (c) is the comparison pattern of FeOOH and Ba-FeOOH Fe 2p energy level diagram of X-ray photoelectron spectroscopy (XPS); (d) is Ba 3d energy level diagram of Ba-FeOOH XPS.

Figure 5 is a comparison chart of the OER performance of Ba-FeOOH in neutral electrolyte (1mol/L phosphate buffer saline (PBS)) and other samples. Among them, (a) is the linear sweep voltammetry (LSV) curve; (b) is the overpotential comparison chart under different current densities; (c) is the Tafel slope chart; (d) is the electrochemical impedance spectrum (EIS).

In Figure 6, (a) is the voltage stability curve of FeOOH and Ba-FeOOH at low current density in neutral electrolyte (1mol/LPBS); (b) is the voltage stability curve of Ba-FeOOH in neutral electrolyte (1mol/LPBS) Voltage stability curves at medium and high current densities.

Detailed ways

In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention and are not intended to limit the present invention.

The specific implementation of the present invention will be described in detail below with reference to specific embodiments.

A method for preparing barium-modified iron oxyhydroxide, which uses a hydrothermal method to synthesize a barium-modified iron oxyhydroxide nanosheet array grown on a metal foam substrate. In the barium-modified iron oxyhydroxide nanosheet array, iron The atomic content is 10.59-29.33%, the barium atomic content is 0.86-3.78%, and the thickness of the barium-modified iron oxyhydroxide nanosheet array is 5-70nm.

As an embodiment of the present invention, the specific steps are: place the metal foam in a polytetrafluoroethylene reactor, add urea, ammonium fluoride, iron salt, barium salt and deionized water respectively, and perform the reaction using a hydrothermal method , the hydrothermal temperature is 100-180°C, the hydrothermal time is 4-24h, after the reaction is completed, cool to room temperature, take it out, wash it and dry it in an oven to obtain barium-modified iron oxyhydroxide grown on the metal foam. Nanosheet array.

As an embodiment of the present invention, the metal foam is any one of nickel foam, iron foam, nickel-iron foam and copper foam.

As an embodiment of the present invention, the concentration of urea is 0.017-0.167 mol/L, and the concentration of ammonium fluoride is 0.083-0.333 mol/L.

As an embodiment of the present invention, the iron salt is any one of Fe(NO ₃ ) ₃ , Fe ₂ (SO ₄ ) ₃ and FeCl ₃ , and the concentration of the iron salt is 0.008-0.100mol/L. .

As an embodiment of the present invention, the barium salt is Ba(NO ₃ ) ₂ or BaCl ₂ , and the concentration of the barium salt is 0.008-0.100 mol/L.

A barium-modified iron oxyhydroxide nanosheet array prepared according to the method.

Application of a barium-modified iron oxyhydroxide in electrocatalytic water oxidation reaction. The specific application method is: placing the barium-modified iron oxyhydroxide nanosheet array in a neutral electrolyte as an oxygen evolution electrode for neutral water oxidation reaction; the neutral electrolyte is a phosphate buffer, and the neutral electrolyte is The concentration is 1mol/L.

In the embodiment of the present invention, preferably, the barium-modified iron oxyhydroxide nanosheet array is placed in a neutral three-electrode system as an oxygen evolution electrode, the carbon rod is used as the counter electrode, the calomel electrode is used as the reference electrode, and the electrolyte is 0.355 mol/L potassium dihydrogen phosphate and 0.645 mol/L dipotassium hydrogen phosphate, the pH of the solution is 7, and the neutral water oxidation reaction performance test is carried out.

Example 1. The embodiment of the present invention provides a method for preparing a barium-modified iron oxyhydroxide nanosheet array. The steps of the method are as follows: The steps of the method are as follows:

Place 2cm*5cm nickel foam in 3mol/L hydrochloric acid solution, absolute ethanol and deionized water and ultrasonicate for 15mins. Then place the cleaned nickel foam in 60mL containing 0.033mmol/LFe(NO ₃ ) ₃ and 0.033 In a solution of mmol/LBa(NO ₂ ) ₂ , 0.1mmol/L urea and 0.167mmol/L ammonium fluoride, react using hydrothermal method at 140°C for 5 hours. After the reaction is completed and cooled to room temperature, the catalyst is repeatedly rinsed with absolute ethanol and deionized water, and then dried in an oven set at 60°C for 5 hours to obtain a barium-modified iron oxyhydroxide nanosheet array grown on nickel foam. Catalyst (denoted as "Ba-FeOOH").

The embodiment of the present invention provides an application of a barium-modified iron oxyhydroxide nanosheet array. The specific application steps are as follows: use the prepared barium-modified iron oxyhydroxide nanosheet array as a working electrode and a calomel electrode as a reference. The electrode and the graphite rod electrode are the counter electrodes to form a three-electrode system, which is placed in a neutral electrolyte to test its water oxidation performance. The electrolyte is 1 mol/L phosphate buffer. The overpotentials for neutral water oxidation of this sample at current densities of 10 and 300 mA/ ^cm are shown in Table 1.

Figures 1 and 2 are SEM images of the prepared Ba-FeOOH and FeOOH catalysts respectively. The specific steps are: observe the sample morphology of the prepared catalyst on JEOL JSM-7900, and the electron beam intensity is 12.6keV. It can be seen that both have the morphology of nanosheet arrays, and the thickness of Ba-FeOOH nanosheets is 5-70nm. This is because the modification of Ba makes the FeOOH sheets more uniform and dense.

Figure 3 shows the EDS element distribution diagram of the prepared Ba-FeOOH catalyst. The specific steps are: observe the morphology of the prepared catalyst on JEOL 2100F, and use energy dispersive spectroscopy equipped with the QUANTAX 200-TEM model to study the distribution of each element of the catalyst. It can be seen that Fe, Ba and O elements are uniformly distributed on the nanosheets, successfully proving the formation of FeOOH and the incorporation of Ba into the nanosheets.

Figure 4(a) shows the XRD patterns of the prepared FeOOH and Ba-FeOOH catalysts. The specific steps are: collect the XRD patterns of the prepared catalysts on the X'Pert PRO. It can be seen that the characteristic peaks on the XRD spectrum match Ni (PDF#4-850), FeOOH (PDF#01-0662) and Ba-FeO _x (PDF#28-0141), indicating the successful synthesis of iron oxyhydroxide. and the successful incorporation of Ba. Figure 4(b) shows the comparison of the Raman spectra of FeOOH and Ba-FeOOH. The specific steps are: collect the Raman spectrum signal on the HORIBALabRAM, and its laser wavelength is 532nm. It can be found that both samples have characteristic peaks belonging to FeOOH, and after Ba modification, Ba-FeOOH has Ba-O characteristic peaks, indicating the successful introduction of Ba. Figure 4(c) shows the Fe 2p energy level spectrum comparison of XPS of FeOOH and Ba-FeOOH. It can be found that after Ba modification, the Fe ³⁺ peak of the catalyst moves to high energy, representing an increase in the Fe valence state. Figure 4(d) shows the Ba 3d energy level spectrum comparison of XPS of Ba-FeOOH. The 3d splitting peak spacing of Ba is 15.3eV, indicating that the oxidation state of Ba element is +2 valence. The specific steps for XPS spectrum collection are: collect XPS signals on the ESCALAB 250XI (Thermo) system.

Figure 5(a) and Figure 5(b) show the linear scan voltammetry (LSV) curves and detailed OER overpotential comparison diagrams of FeOOH, Ba-FeOOH and IrO ₂ samples in 1 mol/L phosphate buffer solution, respectively. It can be found that the introduction of Ba significantly improves the OER performance of FeOOH. At current densities of 10 and 300 mA/cm ² , the required OER overpotential is only as low as 268 and 578 mV, which is far better than the IrO ₂ sample. The Tafel slope of these samples was further calculated. As shown in Figure 5(c), the Ba-FeOOH sample has a low Tafel slope of 128mV/dec, indicating that Ba modification is beneficial to promote faster OER reaction kinetics. . At the same time, Ba modification is also beneficial to improving the conductivity of FeOOH, thereby promoting rapid electron transfer on the catalyst, as shown in the electrochemical impedance diagram of Figure 5(d), which shows the smaller charge transfer resistance of Ba-FeOOH.

Figure 6(a) shows the stability comparison chart of FeOOH and Ba-FeOOH samples in 1mol/L PBS solution at a current density of 10mA/ ^cm2 . It can be found that the introduction of Ba greatly improves the stability of FeOOH. At a current density of 10mA/ ^cm2 , the Ba-FeOOH sample can operate stably for 200 hours, while the performance of the FeOOH sample gradually decays within 40 hours of operation. Figure 6(b) shows the stability of the Ba-FeOOH sample in 1 mol/LPBS solution at ^a current density of 300 mA/cm. At a high current density of 300mA/ ^cm2 , the Ba-FeOOH sample can operate stably for more than 50h, demonstrating its excellent stability.

Example 2. The embodiment of the present invention provides a method for preparing a barium-modified iron oxyhydroxide nanosheet array. The steps of the method are as follows:

Place 2cm*5cm iron foam in 3mol/L hydrochloric acid solution, absolute ethanol and deionized water and ultrasonicate for 15mins. Then place the cleaned iron foam in 60mL containing 0.008mmol/LFe(NO ₃ ) ₃ and 0.067 In a solution of mmol/LBaCl ₂ , 0.167mmol/L urea and 0.333mmol/L ammonium fluoride, react using hydrothermal method at 120°C for 5 hours. After the reaction is completed and cooled to room temperature, the catalyst is washed repeatedly with absolute ethanol and deionized water, and then dried in an oven set at 60°C for 5 hours to obtain a barium-modified iron oxyhydroxide nanosheet array grown on iron foam. catalyst.

The embodiment of the present invention provides an application of a barium-modified iron oxyhydroxide nanosheet array. The specific application steps are as follows: use the prepared barium-modified iron oxyhydroxide nanosheet array as a working electrode and a calomel electrode as a reference. A three-electrode system consisting of a counter electrode and a graphite rod electrode was placed in a neutral electrolyte to test its water oxidation performance. The electrolyte was 1 mol/L phosphate buffer. The overpotentials for neutral water oxidation of this sample at current densities of 10 and 300 mA/ ^cm are shown in Table 1.

Example 3. The embodiment of the present invention provides a method for preparing a barium-modified iron oxyhydroxide nanosheet array. The steps of the method are as follows:

Place 2cm*5cm nickel foam in 3mol/L hydrochloric acid solution, absolute ethanol and deionized water and ultrasonicate for 15mins, then place the cleaned nickel foam in 60mL containing 0.017mmol/LFe ₂ (SO ₄ ) ₃ , In a solution of 0.008mmol/LBa(NO ₂ ) ₂ , 0.017mmol/L urea and 0.083mmol/L ammonium fluoride, react using hydrothermal method at 100°C for 12h. After the reaction is completed and cooled to room temperature, the catalyst is repeatedly rinsed with absolute ethanol and deionized water, and then dried in an oven set at 60°C for 5 hours to obtain a barium-modified iron oxyhydroxide nanosheet array grown on nickel foam. catalyst.

The embodiment of the present invention provides an application of a barium-modified iron oxyhydroxide nanosheet array. The specific application steps are as follows: use the prepared barium-modified iron oxyhydroxide nanosheet array as a working electrode and a calomel electrode as a reference. A three-electrode system consisting of a counter electrode and a graphite rod electrode was placed in a neutral electrolyte to test its water oxidation performance. The electrolyte was 1 mol/L phosphate buffer. The overpotentials for neutral water oxidation of this sample at current densities of 10 and 300 mA/ ^cm are shown in Table 1.

Example 4. This embodiment of the present invention provides a method for preparing a barium-modified iron oxyhydroxide nanosheet array. The steps of the method are as follows:

Place 4cm*10cm nickel-iron foam in 3mol/L hydrochloric acid solution, absolute ethanol and deionized water and sonicate for 15mins, then place the cleaned nickel-iron foam into 60mL containing 0.100mmol/LFeCl ₃ and 0.033mmol/ In a solution of LBaCl ₂ , 0.067mmol/L urea and 0.250mmol/L ammonium fluoride, react using hydrothermal method at 180°C for 4 hours. After the reaction is completed and cooled to room temperature, the catalyst is washed repeatedly with absolute ethanol and deionized water, and then dried in an oven set at 60°C for 5 hours to obtain barium-modified iron oxyhydroxide nanosheets grown on nickel-iron foam. Array Catalyst.

The embodiment of the present invention provides an application of a barium-modified iron oxyhydroxide nanosheet array. The specific application steps are as follows: use the prepared barium-modified iron oxyhydroxide nanosheet array as a working electrode and a calomel electrode as a reference. A three-electrode system consisting of a counter electrode and a graphite rod electrode was placed in a neutral electrolyte to test its water oxidation performance. The electrolyte was 1 mol/L phosphate buffer. The overpotentials for neutral water oxidation of this sample at current densities of 10 and 300 mA/ ^cm are shown in Table 1.

Example 5. The embodiment of the present invention provides a method for preparing a barium-modified iron oxyhydroxide nanosheet array. The steps of the method are as follows:

Place 3cm*7.5cm nickel foam in 3mol/L hydrochloric acid solution, absolute ethanol and deionized water and ultrasonicate for 15mins, then place the cleaned nickel foam in 60mL containing 0.033mmol/L Fe(NO ₃ ) ₃ , 0.100mmol/LBaCl ₂ , 0.050mmol/L urea and 0.133mmol/L ammonium fluoride solution, using the hydrothermal method to react at 100°C for 16h. After the reaction is completed and cooled to room temperature, the catalyst is repeatedly rinsed with absolute ethanol and deionized water, and then dried in an oven set at 60°C for 5 hours to obtain a barium-modified iron oxyhydroxide nanosheet array grown on nickel foam. catalyst.

The embodiment of the present invention provides an application of a barium-modified iron oxyhydroxide nanosheet array. The specific application steps are as follows: use the prepared barium-modified iron oxyhydroxide nanosheet array as a working electrode and a calomel electrode as a reference. A three-electrode system consisting of a counter electrode and a graphite rod electrode was placed in a neutral electrolyte to test its water oxidation performance. The electrolyte was 1 mol/L phosphate buffer. The overpotentials for neutral water oxidation of this sample at current densities of 10 and 300 mA/ ^cm are shown in Table 1.

Example 6. The embodiment of the present invention provides a method for preparing a barium-modified iron oxyhydroxide nanosheet array. The steps of the method are as follows:

Place 2cm*5cm copper foam in 3mol/L hydrochloric acid solution, absolute ethanol and deionized water and sonicate for 15mins, then place the cleaned copper foam in 60mL containing 0.067mmol/L FeCl ₃ and 0.017mmol/L In a solution of Ba(NO ₂ ) ₂ , 0.133mmol/L urea and 0.333mmol/L ammonium fluoride, react at 160°C for 8 hours using hydrothermal method. After the reaction is completed and cooled to room temperature, the catalyst is washed repeatedly with absolute ethanol and deionized water, and then dried in an oven set at 60°C for 5 hours to obtain a barium-modified iron oxyhydroxide nanosheet array grown on copper foam. catalyst.

The embodiment of the present invention provides an application of a barium-modified iron oxyhydroxide nanosheet array. The specific application steps are as follows: use the prepared barium-modified iron oxyhydroxide nanosheet array as a working electrode and a calomel electrode as a reference. A three-electrode system consisting of a counter electrode and a graphite rod electrode was placed in a neutral electrolyte to test its water oxidation performance. The electrolyte was 1 mol/L phosphate buffer. The overpotentials for neutral water oxidation of this sample at current densities of 10 and 300 mA/ ^cm are shown in Table 1.

Table 1 Summary table of neutral water oxidation performance of Ba-FeOOH samples prepared in different embodiments

In summary, the present invention has developed a one-step hydrothermal method to introduce the alkaline earth metal barium element during the growth process of iron oxyhydroxide to form a barium-modified iron oxyhydroxide nanosheet array. The preparation method is simple and efficient. The nanosheet array grown on the metal foam substrate can fully expose the active sites. At the same time, the modification of barium is beneficial to enhance the conductivity of iron oxyhydroxide, improve the electron transfer ability, thereby promoting the reaction kinetics of the oxygen evolution reaction, and ultimately Significantly improve the neutral water oxidation performance of the electrode.

Barium-modified iron oxyhydroxide nanosheet arrays serve as neutral water oxidation electrodes and exhibit excellent catalytic activity and stability. At current densities of 10 and 300 mA/ ^cm , the required OER overpotentials in neutral aqueous solution are as low as 268 and 578 mV, which are much lower than the individual iron oxyhydroxide nanosheet array samples. At the same time, the catalyst can operate for 200 and 50 hours at constant current densities of 10 and 300 mA/ ^cm , respectively, without significant degradation in water oxidation performance. This performance is superior to most non-precious metal catalysts in the existing technology.

The above are only the preferred embodiments of the present invention. It should be pointed out that those skilled in the art can also make several modifications and improvements without departing from the concept of the present invention, and these should also be regarded as the protection scope of the present invention. , none of these will affect the effect of the present invention and the practicality of the patent.

Claims (10)

1. A method for preparing barium-modified iron oxyhydroxide, characterized in that: a barium-modified iron oxyhydroxide nanosheet array grown on a metal foam substrate is synthesized by a hydrothermal method, and the barium-modified iron oxyhydroxide is synthesized in In the nanosheet array, the iron atomic content is 10.59-29.33%, and the barium atomic content is 0.86-3.78%. 2. The preparation method of barium-modified iron oxyhydroxide according to claim 1, characterized in that the specific steps are: placing the metal foam in a polytetrafluoroethylene reactor, and adding urea, ammonium fluoride and iron salt respectively. , barium salt and deionized water, use hydrothermal method to react. The hydrothermal temperature is 100-180 ℃, and the hydrothermal time is 4-24 h. After the reaction is completed, cool to room temperature, take it out, wash it and dry it in the oven. That is, a barium-modified iron oxyhydroxide nanosheet array grown on metal foam is obtained. 3. The preparation method of barium-modified iron oxyhydroxide according to claim 2, characterized in that the thickness of the barium-modified iron oxyhydroxide nanosheet array is 5-70 nm. 4. The preparation method of barium-modified iron oxyhydroxide according to claim 2, characterized in that the metal foam is any one of nickel foam, iron foam, nickel-iron foam and copper foam. 5. The preparation method of barium-modified iron oxyhydroxide according to claim 2, characterized in that the concentration of the urea is 0.017-0.167 mol/L, and the concentration of the ammonium fluoride is 0.083-0.333 mol/ L. 6. The preparation method of barium-modified iron oxyhydroxide according to claim 2, characterized in that the iron salt is any one of Fe( _NO3 ) ₃ , _Fe2 ( _SO4 ) ₃ and _FeCl3 species, the concentration of the iron salt is 0.008-0.100 mol/L. 7. The preparation method of barium-modified iron oxyhydroxide according to claim 2, characterized in that the barium salt is Ba(NO ₃ ) ₂ or BaCl ₂ , and the concentration of the barium salt is 0.008-0.100 mol. /L. 8. A barium-modified iron oxyhydroxide nanosheet array prepared according to the method of any one of claims 1-7. 9. Application of the barium-modified iron oxyhydroxide according to claim 8 in electrocatalytic water oxidation reaction. 10. The application according to claim 9, characterized in that the specific application method is: placing the barium-modified iron oxyhydroxide nanosheet array in a neutral electrolyte as an oxygen evolution electrode for neutral water oxidation reaction; The neutral electrolyte is phosphate buffer, and the concentration of the neutral electrolyte is 1 mol/L.