CN115385392A - A nanoporous perovskite oxide and its preparation method and application - Google Patents

Abstract

The invention belongs to the technical field of nanoporous materials, and in particular relates to a nanoporous perovskite oxide and its preparation method and application. The perovskite oxide described in the present invention includes the following elements: La element, Ca element, M element and O element; wherein, the M element is one or both of Co element and Ni element. On the one hand, it does not contain noble metal elements, so the price is relatively low and the material is easy to obtain; at the same time, the selection of Co and Ni elements to occupy the B site of the perovskite oxide is beneficial to promote the electrochemical performance of the electrocatalytic material. The preparation method of the invention combines the alloy design, the dealloying method and the annealing process, and transforms the bulk alloy into a nano-porous perovskite oxide with a high specific surface area. The method is simple and can effectively prepare the perovskite oxide, which has a nanoporous structure and a large specific surface area.

Description

A nanoporous perovskite oxide and its preparation method and application

technical field

The invention belongs to the technical field of nanoporous materials, and in particular relates to a nanoporous perovskite oxide and its preparation method and application.

Background technique

The implementation of new energy technologies, including electrocatalysis, solar cells, fuel cells, water splitting, and metal-air batteries, is crucial to the sustainable development of society and has received extensive attention in recent years. In these technologies, because multiple reactions involve multilevel electron transfer and proton coupling processes, the proper use of catalysts is an effective way to reduce the reaction overpotential and improve energy conversion efficiency. Currently, noble metal-based electrocatalysts (such as Pt-based, Pd-based, Ir-based, etc.) usually exhibit high catalytic activity in these reactions, however, their scarcity and high cost limit their wide application. To overcome this problem, perovskite-type oxides, which are rich in raw materials, low in cost, wide in variety, and have excellent electrocatalytic properties, have gradually become one of the alternative electrocatalytic materials.

The general structural formula of the perovskite oxide is ABO ₃ (where the A-position ions are usually alkaline earth or rare earth metal ions, and the B-position ions are usually transition metal ions). When all or part of electronegative metal ions are substituted, lattice defects in the form of cation vacancies or oxyanion vacancies are often induced, and the crystal structure will not change significantly (crystal structure stability), but the physical and chemical properties usually occur wonderfully. The change. Moreover, due to the change of ion valence (abnormal atomic valence, mixed atomic valence) and the generation of lattice defects in the form of vacancies, the electrical conductivity and material transport rate of oxides are greatly improved, showing stronger functionality, such as higher catalytic activity, stability, etc.

At present, there are many methods for preparing perovskite materials. For example, a method for hydrothermally synthesizing Ba-doped Sr ₂ Fe _1.5 Mo _0.5 O ₆ double perovskite nanomaterials is disclosed in the prior art. According to the stoichiometry of Sr, Ba, Fe and Mo in the perovskite material, number, the raw materials were added to water in sequence, and then complexing agent citric acid and dispersant polyethylene glycol were added to obtain a precursor solution; then the precursor solution was hydrothermally reacted, centrifuged, washed and dried; finally calcined in the atmosphere , to obtain the nanomaterial. The double perovskite anode material prepared by the invention has good performance as the anode material of solid oxide fuel cell. As another example, the prior art also discloses a method for preparing perovskite material CsPbX ₃ , which adopts a simple microwave heating synthesis process. First, the cesium precursor and the lead precursor are mixed in a microwave bottle at room temperature, and then Add octadecene, polar solvent and surfactant to obtain a mixed solvent; ultrasonically dissolve the mixed solvent at room temperature, place it in a microwave heating device to heat the reaction, stop microwave heating after the reaction and cool it, and then the reaction solution Rapid cooling; finally, adding a cleaning agent to the rapidly cooled reaction liquid, and centrifugal washing to obtain a solid CsPbX ₃ perovskite material. However, facile techniques for direct conversion of bulk alloys into nanoporous perovskite oxides and their application in the field of electrocatalysis have not yet been reported.

Contents of the invention

In order to solve the problems in the above-mentioned prior art, the present invention provides a nanoporous perovskite oxide and its preparation method and application. The (La, Ca)MO ₃ (M=Co, Ni) calcium of the present invention Titanium bifunctional electrocatalytic materials not only have excellent electrocatalytic activity for oxygen evolution reaction (OER), but also have excellent performance and stability for oxygen reduction reaction (ORR).

To achieve the above object, the present invention adopts the following technical solutions:

A nanoporous perovskite-type oxide, the perovskite-type oxide is (La, Ca)MO ₃ (M=Co, Ni); its microscopic appearance is a nanoporous structure, and the pore size of the nanoporous 1-100nm.

The invention also provides a preparation method of the nanoporous perovskite oxide. The preparation method realizes the transformation of the bulk alloy into a nanoporous perovskite oxide with a high specific surface area, the preparation method is simple, the conditions are easy to realize, the cost is low, and it can be produced on a large scale, and has good application prospects.

A preparation method of nanoporous perovskite oxide combines alloy design, dealloying method and annealing process to transform bulk alloy into nanoporous perovskite oxide with high specific surface area.

The preparation method of above-mentioned perovskite oxide comprises the following steps:

(1) In terms of alloy design, select raw metals with a purity greater than 99.9%, and mix according to each atomic ratio; place the configured raw materials in a vacuum electric arc furnace for melting to obtain a uniform alloy ingot; then Alloy ingots were prepared in a vacuum strip machine to obtain alloy strips.

(2) In terms of dealloying, put the alloy strip in step (1) into a certain concentration of corrosion solution, carry out chemical dealloying, and clean to remove corrosion products and impurities, and vacuum the cleaned sample at a certain temperature dry.

(3) In terms of annealing treatment, put the dealloyed sample obtained in step (2) into a muffle furnace, heat up at a certain heating rate, and then perform annealing treatment at a certain temperature. After keeping the heat for several hours, the furnace is cooled. After cooling to room temperature, the nanoporous perovskite oxide can be obtained.

According to the present invention, preferably, the original metal in step (1) is Al element, La element, Ca element, M element; preferably, the M element is one or both of Co element and Ni element.

According to the present invention, preferably, the atomic percentages in step (1) are Al element: 88%, La element: 3%, Ca element: 3%, M element: 6%.

According to the present invention, preferably, the etching solution in step (2) is NaOH solution.

According to the present invention, preferably, the concentration of the etching solution in step (2) is 2M.

According to the present invention, preferably, the vacuum drying temperature in step (2) is 60°C.

According to the present invention, preferably, the heating rate in step (3) is 4° C./min.

According to the present invention, preferably, the annealing temperature in step (3) is 800°C.

According to the present invention, preferably, the annealing holding time in step (3) is 2 hours.

In an optional embodiment, the operation steps of melting each raw material in a vacuum electric arc furnace to obtain a uniform alloy ingot specifically include:

Place the prepared raw materials in the smelting pit of the vacuum electric arc furnace;

Carry out vacuum treatment and fill with high-purity argon;

Under the protection of high-purity argon, the alloy ingot is obtained by repeated melting for many times.

In an optional embodiment, the operation steps of vacuumizing and filling with high-purity argon specifically include:

After rough pumping by mechanical pump and fine pumping by molecular pump, after the vacuum degree of the equipment chamber reaches 3×10 ^-3 Pa, it is filled with high-purity argon gas; after vacuuming again to 3×10 ^-3 Pa, it is filled with high-purity argon again gas.

In an optional embodiment, under the protection of high-purity argon, in the step of repeatedly melting and obtaining alloy ingots:

The number of melting times is 4 to 7 times.

In an optional embodiment, the operation steps of preparing alloy strips by casting alloy ingots in a vacuum strip machine specifically include:

Breaking the alloy ingot, and placing a part of the broken alloy ingot as a master alloy in the quartz tube of the vacuum stripping machine;

After adjusting the vacuum degree of the furnace cavity of the vacuum belt throwing machine to 2×10 ^-3 Pa, start the stepless speed regulation motor, and turn on the induction coil power supply after the copper roller speed reaches the preset speed, so that the master alloy in the quartz tube is completely melted to obtain Alloy melt;

Instantly fill the quartz tube with high-purity argon, so that a preset pressure difference is formed between the inside of the quartz tube and the furnace chamber of the vacuum stripping machine, and the alloy melt is driven to spray from the nozzle of the quartz tube under the action of the preset pressure difference to the surface of the copper roll, and rapidly cooled to form alloy strips.

In an optional embodiment, the preset rotational speed of the copper roller is 2000-3500rpm;

The preset pressure difference formed between the quartz tube and the furnace cavity is 0.03-0.05 MPa.

In an optional embodiment, the operation steps of putting the alloy strip into a 2M NaOH solution to remove the Al component and cleaning to remove impurities specifically include:

Put the alloy strip into a 150mL beaker, then pour 2M NaOH solution, let it stand for a while until no bubbles appear in the beaker, pour out the supernatant, and wash with water and ethanol for 5-6 times to remove impurities .

In an optional embodiment, the cleaned and dried sample is vacuum-dried at 60°C and then annealed to obtain a nanoporous perovskite oxide. The steps include:

Put the cleaned and dried samples into a vacuum drying oven, set the temperature at 60° C., and use a vacuum pump to pump out the air in the vacuum drying oven. The drying time is 11 to 12 hours. Put the dried product into a crucible, heat it in a muffle furnace at a rate of 4°C/min to 800°C for 2h, and then perform a furnace cooling treatment to prepare a nanoporous perovskite oxide.

The invention also discloses the application of the above-mentioned nanoporous perovskite oxide, and the perovskite oxide is used as an electrocatalytic material.

Beneficial effect

A perovskite oxide according to the present invention includes the following elements: La element, Ca element, M element and O element; wherein, the M element is one or both of Co element and Ni element. On the one hand, it does not contain noble metal elements, so the price is relatively low and the material is easy to obtain; at the same time, the selection of Co and Ni elements to occupy the B site of the perovskite oxide is beneficial to promote the electrochemical performance of the electrocatalytic material.

The preparation method of the invention combines alloy design, dealloying method and annealing process to transform bulk alloy into nano-porous perovskite oxide with high specific surface area. It uses a non-consumable vacuum electric arc furnace to obtain alloy ingots with uniform composition, and then obtains alloy strips after vacuum stripping, then removes Al elements by dealloying technology, and then anneals to obtain nanoporous perovskite oxides. The method is simple and can effectively prepare the perovskite oxide, which has a nanoporous structure and a large specific surface area.

Description of drawings:

Fig. 1 is the X-ray diffraction patterns of the dealloyed samples prepared in Example 1 and Comparative Examples 1 and 2 of the present invention.

FIG. 2 is an X-ray diffraction pattern of the perovskite oxide prepared in Example 1 and Comparative Examples 1 and 2 of the present invention.

FIG. 3 is a scanning electron micrograph a of the perovskite oxide electrocatalytic material prepared in Example 1. FIG.

FIG. 4 is a scanning electron micrograph b of the perovskite oxide electrocatalytic material prepared in Example 1. FIG.

Fig. 5 is the ORR polarization curve of the perovskite-type oxide electrocatalytic materials prepared in Example 1 and Comparative Examples 1 and 2 in O ₂ saturated 0.1M KOH solution at a scan rate of 10 mV/s.

Fig. 6 is the OER polarization curve of the perovskite-type oxide electrocatalytic materials prepared in Example 1 and Comparative Examples 1 and 2 in O ₂ saturated 1M KOH solution at a scan rate of 10 mV/s.

Detailed ways

Hereinafter, the present invention will be described in detail. Before proceeding with the description, it should be understood that the terms used in this specification and appended claims should not be construed as limited to ordinary and dictionary meanings, but should be best interpreted while allowing the inventor to properly define the terms On the basis of the principles of the present invention, explanations are made based on meanings and concepts corresponding to the technical aspects of the present invention. Accordingly, the descriptions set forth herein are preferred examples for illustrative purposes only and are not intended to limit the scope of the invention, so that it should be understood that other, etc. price or improvement.

The following examples are only listed as examples of embodiments of the present invention, and do not constitute any limitation to the present invention. Those skilled in the art can understand that modifications within the scope of not departing from the essence and design of the present invention all fall into the protection of the present invention. scope. Unless otherwise specified, the reagents and instruments used in the following examples are all commercially available products.

Terminology Explanation:

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

Example 1

This embodiment provides a perovskite oxide La _0.5 Ca _0.5 Co _0.5 Ni _0.5 O ₃ , which is prepared by the following method:

(1) Raw metals Al, La, Ca, Co and Ni elements with a purity greater than 99.9% are formulated according to the atomic percentage of 88:3:3:3:3;

(2) Smelting the above-mentioned high-purity metals in a vacuum electric arc furnace, specifically including:

Place the prepared raw materials in the smelting pit of the vacuum electric arc furnace;

Through mechanical pump rough pumping and molecular pump fine pumping, after the vacuum degree of the equipment chamber reaches 3× ^{10 -3} Pa, it is filled with high-purity argon gas; pure argon;

Under the protection of high-purity argon, the alloy ingot is repeatedly smelted 4 to 7 times to obtain an alloy ingot with uniform composition.

(3) Alloy ingots are carried out in the vacuum strip machine to get rid of the strips to obtain alloy strips, which specifically include:

The alloy ingot is broken, and a part of the broken alloy ingot is placed as a master alloy in the quartz tube of the vacuum stripping machine (nozzle section is 0.2×3mm ² );

When the vacuum degree of the furnace chamber of the vacuum stripping machine reaches 2×10 ^-3 Pa, start the stepless speed regulation motor, and turn on the power supply of the induction coil after the copper roller speed reaches 3500rpm (the surface line speed is about 35m/s), so that the quartz The master alloy rod in the tube is completely melted;

Then, high-purity argon gas is instantly filled into the quartz tube, and a pressure difference (0.05MPa) is established between the quartz tube and the furnace chamber, driving the alloy melt to be directly sprayed onto the high-speed rotating copper roller, and rapidly cooled to form strips.

(4) Dealloying and annealing the alloy strips to obtain nanoporous perovskite oxides, specifically including:

Put the alloy strips into a 150mL beaker, then pour a sufficient amount of 2M NaOH solution, and let it stand at room temperature for a period of time. When no bubbles appear in the beaker, pour out the supernatant and wash with water and absolute ethanol respectively 5-6 times to remove impurities.

Put the cleaned alloy into a vacuum drying oven, set the temperature at 60° C., and use a vacuum pump to pump out the air in the vacuum drying oven. The drying time is 11 to 12 hours. Put the dried product in a crucible, put the crucible into a muffle furnace, raise the temperature to 800°C at a rate of 4°C/min, keep it warm for 2 hours, and then perform a furnace cooling treatment to prepare a nanoporous perovskite oxide .

After testing, the phase structure of the dealloyed sample in this embodiment is shown in FIG. 1 , and the phase structure of the annealed sample in this embodiment is shown in FIG. 2 . It can be seen from the figure that the main phase after annealing is perovskite structure. The scanning electron microscope images (SEM) of the perovskite-type oxide prepared in this embodiment are shown in FIGS. 3 and 4 . It can be seen from Figures 3 and 4 that the prepared sample has a nanoporous structure, and the nanoporous pore diameter is 1-100 nm. The electrocatalytic properties of the perovskite-type oxides prepared in this example are shown in Figures 5 and 6, and it can be seen from Figures 5 and 6 that the perovskite-type oxides prepared in this example have excellent oxygen reduction (ORR ) and oxygen evolution (OER) performance.

Comparative example 1

This embodiment provides a perovskite oxide La _0.5 Ca _0.5 NiO ₃ , which is prepared by the following method:

(1) Raw metals Al, La, Ca and Ni elements with a purity greater than 99.9% are formulated according to the atomic percentage of 88:3:3:6;

(2) Melting the above-mentioned high-purity metal in a vacuum electric arc furnace;

Wherein, step (2) specifically includes:

Place the prepared raw materials in the smelting pit of the vacuum electric arc furnace;

Through mechanical pump rough pumping and molecular pump fine pumping, after the vacuum degree of the equipment chamber reaches 3× ^{10 -3} Pa, it is filled with high-purity argon gas; pure argon;

Under the protection of high-purity argon, the alloy ingot is repeatedly smelted 4 to 7 times to obtain an alloy ingot with uniform composition.

(3) the alloy ingot is carried out in a vacuum strip machine to throw away the strip to obtain the alloy strip;

Wherein, step (3) specifically includes:

The alloy ingot is broken, and a part of the broken alloy ingot is placed as a master alloy in the quartz tube of the vacuum stripping machine (nozzle section is 0.2×3mm ² );

When the vacuum degree of the furnace chamber of the vacuum stripping machine reaches 2×10 ^-3 Pa, start the stepless speed regulation motor, and turn on the power supply of the induction coil after the copper roller speed reaches 3500rpm (the surface line speed is about 35m/s), so that the quartz The master alloy rod in the tube is completely melted;

Then, high-purity argon gas is instantly filled into the quartz tube, and a pressure difference (0.05MPa) is established between the quartz tube and the furnace chamber, driving the alloy melt to be directly sprayed onto the high-speed rotating copper roller, and rapidly cooled to form strips.

(4) Dealloying and annealing the alloy strips to obtain nanoporous perovskite oxides.

Wherein, step (4) specifically includes:

Put the alloy strips into a 150mL beaker, then pour a sufficient amount of 2M NaOH solution, and let it stand at room temperature for a period of time. When no bubbles appear in the beaker, pour out the supernatant and wash with water and absolute ethanol respectively 5-6 times to remove impurities.

Put the cleaned alloy into a vacuum drying oven, set the temperature at 60° C., and use a vacuum pump to pump out the air in the vacuum drying oven. The drying time is 11 to 12 hours. Put the dried product in a crucible, put the crucible into a muffle furnace, raise the temperature to 800°C at a rate of 4°C/min, keep it warm for 2 hours, and then perform a furnace cooling treatment to prepare a nanoporous perovskite oxide .

After testing, the phase structure of the dealloyed sample in this embodiment is shown in FIG. 1 , and the phase structure of the annealed sample in this embodiment is shown in FIG. 2 . It can be seen from the figure that the main phase after annealing is perovskite structure.

Comparative example 2

This embodiment provides a perovskite oxide La _0.5 Ca _0.5 CoO ₃ , which is prepared by the following method:

(1) Raw metals Al, La, Ca and Co elements with a purity greater than 99.9% are formulated according to the atomic percentage of 88:3:3:6;

(2) Melting the above-mentioned high-purity metal in a vacuum electric arc furnace;

Wherein, step (2) specifically includes:

Place the prepared raw materials in the smelting pit of the vacuum electric arc furnace;

Through mechanical pump rough pumping and molecular pump fine pumping, after the vacuum degree of the equipment chamber reaches 3× ^{10 -3} Pa, it is filled with high-purity argon gas; pure argon;

Under the protection of high-purity argon, the alloy ingot is repeatedly smelted 4 to 7 times to obtain an alloy ingot with uniform composition.

(3) the alloy ingot is carried out in a vacuum strip machine to throw away the strip to obtain the alloy strip;

Wherein, step (3) specifically includes:

The alloy ingot is broken, and a part of the broken alloy ingot is placed as a master alloy in the quartz tube of the vacuum stripping machine (nozzle section is 0.2×3mm ² );

When the vacuum degree of the furnace chamber of the vacuum stripping machine reaches 2×10 ^-3 Pa, start the stepless speed regulation motor, and turn on the power supply of the induction coil after the copper roller speed reaches 3500rpm (the surface line speed is about 35m/s), so that the quartz The master alloy rod in the tube is completely melted;

Then, high-purity argon gas is instantly filled into the quartz tube, and a pressure difference (0.05MPa) is established between the quartz tube and the furnace chamber, driving the alloy melt to be directly sprayed onto the high-speed rotating copper roller, and rapidly cooled to form strips.

(4) Dealloying and annealing the alloy strips to obtain nanoporous perovskite oxides.

Wherein, step (4) specifically includes:

Put the alloy strips into a 150mL beaker, then pour a sufficient amount of 2M NaOH solution, and let it stand at room temperature for a period of time. When no bubbles appear in the beaker, pour out the supernatant and wash with water and absolute ethanol respectively 5-6 times to remove impurities.

Put the cleaned alloy into a vacuum drying oven, set the temperature at 60° C., and use a vacuum pump to pump out the air in the vacuum drying oven. The drying time is 11 to 12 hours. Put the dried product in a crucible, put the crucible into a muffle furnace, raise the temperature to 800°C at a rate of 4°C/min, keep it warm for 2 hours, and then perform a furnace cooling treatment to prepare a nanoporous perovskite oxide .

After testing, the phase structure of the dealloyed sample in this embodiment is shown in FIG. 1 , and the phase structure of the annealed sample in this embodiment is shown in FIG. 2 . It can be seen from the figure that the main phase after annealing is perovskite structure.

Application example 1

The ORR performance test method is as follows: a three-electrode system is used, with the glassy carbon electrode coated with the sample as the working electrode, the platinum wire as the counter electrode, and the Hg/HgO electrode as the reference electrode. The electrolyte used is: 0.1M KOH solution. Oxygen was introduced before the test to saturate the oxygen in the electrolyte. The scanning speed is 10mV/s.

Fig. 5 is the ORR polarization curve of the perovskite electrocatalytic material prepared in Example 1 and Comparative Examples 1 and 2 in O ₂ saturated 0.1M KOH solution with a scan rate of 10 mV/s.

It can be seen from Fig. 5 that the La _0.5 Ca _0.5 Co _0.5 Ni _0.5 O ₃ electrocatalytic material prepared in Example 1 is better than the La _0.5 Ca _0.5 NiO ₃ and La _0.5 Ca _0.5 CoO ₃ perovskite electrocatalytic materials prepared in Comparative Example 1 and 2 There is a larger limiting current density of ORR, which can reach 6mAcm ^-2 , which indicates that it has better electrocatalytic performance for oxygen reduction.

Application example 2

The performance LSV test method of OER is as follows: a three-electrode system is used, the glassy carbon electrode coated with the sample is used as the working electrode, the platinum wire is used as the counter electrode, and the Hg/HgO electrode is used as the reference electrode. The electrolyte used is: 1M KOH solution . Oxygen was introduced before the test to saturate the oxygen in the electrolyte. The scanning speed is 10 mV/s.

Fig. 6 is the OER polarization curve of the perovskite electrocatalytic material prepared in Example 1 and Comparative Examples 1 and 2 in O ₂ saturated 1M KOH solution with a scan rate of 10 mV/s.

It can be seen from Fig. 6 that the La _0.5 Ca _0.5 Co _0.5 Ni _0.5 O ₃ electrocatalytic material prepared in Example 1 is better than the La _0.5 Ca _0.5 NiO ₃ and La _0.5 Ca _0.5 CoO ₃ perovskite electrocatalytic materials prepared in Comparative Example 1 and 2 There is a smaller overpotential, when the current density is 10mA/cm ² , the overpotential is only 330mV.

The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art can still understand the foregoing embodiments. Modifications are made to the technical solutions described, or equivalent replacements are made to some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions claimed in the present invention.

Claims (10)

1. A nano-porous perovskite oxide is characterized in thatThe structural general formula of the perovskite type oxide is (La, ca) MO ₃ M is one or two of Co element and Ni element; the micro-morphology of the perovskite type oxide is a nano porous structure.

2. The nanoporous perovskite oxide according to claim 1, wherein the pores of the nanoporous perovskite oxide are between 1 and 100nm in diameter.

3. The nanoporous perovskite oxide according to claim 1, wherein the preparation method comprises the steps of:

(1) Alloy design: selecting original metals, and batching according to each atomic ratio; smelting the prepared raw materials to obtain uniform and consistent alloy ingots; then processing the alloy ingot to obtain an alloy strip;

(2) Dealloying: putting the alloy strip obtained in the step (1) into a corrosive solution with a certain concentration for chemical dealloying, then cleaning to remove corrosion products and impurities, and carrying out vacuum drying on the cleaned sample at a certain temperature to obtain a dealloyed sample;

(3) Annealing treatment: and (3) annealing the dealloying sample obtained in the step (2) at a certain temperature, keeping the temperature for a plurality of hours, cooling the furnace, and cooling to room temperature to obtain the nano porous perovskite type oxide.

4. The nanoporous perovskite-type oxide according to claim 3, wherein in step (1), the purity of the selected original metal is more than 99.9%, and the original metal is Al element, la element, ca element, M element; the M element is one or two of Co element and Ni element; the atomic percentage is Al element: 88% of La element: 3%, ca element: 3%, M element: 6 percent.

5. The nanoporous perovskite oxide according to claim 3, wherein in step (1), the smelting operation comprises in particular:

placing the prepared raw materials in a smelting pit of a vacuum arc furnace;

carrying out vacuum-pumping treatment, and filling high-purity argon: the vacuum degree of the equipment cavity reaches 3 multiplied by 10 by rough pumping of a mechanical pump and fine pumping of a molecular pump ^-3 After Pa, filling high-purity argon; vacuum pumping is carried out again until the vacuum pressure is 3 multiplied by 10 ^-3 After Pa, high-purity argon is filled again;

repeatedly smelting for many times under the protection of high-purity argon to obtain alloy ingots, wherein the smelting times are 4-7 times.

6. The nanoporous perovskite-type oxide according to claim 3, wherein in step (1), the step of processing the alloy ingot to obtain the alloy strip specifically comprises:

crushing the alloy cast ingot, and placing a part of the crushed alloy cast ingot in a quartz tube of a vacuum melt-spun machine as a master alloy;

adjusting the vacuum degree of the furnace chamber of the vacuum melt-spun machine to 2 multiplied by 10 ^-3 After Pa, starting a stepless speed regulating motor, and switching on a power supply of an induction coil after the rotating speed of the copper roller reaches a preset rotating speed so as to completely melt the master alloy in the quartz tube to obtain an alloy melt; the preset pressure difference formed between the quartz tube and the furnace chamber is 0.03-0.05 MPa;

filling high-purity argon into the quartz tube instantly to form a preset pressure difference between the quartz tube and a furnace chamber of the vacuum melt-throwing belt machine, driving the alloy melt to be sprayed to the surface of the copper roller from a nozzle of the quartz tube under the action of the preset pressure difference, and rapidly cooling to form an alloy strip; the preset rotating speed of the copper roller is 2000-3500 rpm.

7. The nanoporous perovskite-type oxide according to claim 3, wherein in step (2), the etching solution is NaOH solution and the etching solution has a concentration of 2M.

8. The nanoporous perovskite oxide according to claim 7, wherein the step (2) of dealloying specifically comprises:

putting the alloy strip into a container, then pouring 2M NaOH solution, standing for a period of time until no bubbles appear in the container, pouring out supernatant, and respectively cleaning the alloy strip with water and ethanol for 5-6 times to remove impurities;

and (3) putting the cleaned and dried alloy strip into a vacuum drying oven, setting the temperature to be 60 ℃, and pumping out air in the vacuum drying oven by using a vacuum pump, wherein the drying time is 11-12h.

9. The nanoporous perovskite oxide according to claim 3, wherein the annealing treatment of step (3) comprises in particular the following operating steps: and (3) putting the dealloyed sample obtained in the step (2) into a crucible, heating to 800 ℃ at a speed of 4 ℃/min in a muffle furnace, preserving heat for 2 hours, and then carrying out furnace cooling treatment to prepare the nano porous perovskite type oxide.

10. Use of a nanoporous perovskite oxide as defined in any one of claims 1 to 9 as electrocatalytic material.

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