Preparation method of iridium-nickel-cobalt-copper-iron high-entropy oxide nanomaterial

Abstract

The application discloses a preparation method of an iridium-nickel-cobalt-copper-iron high-entropy oxide nanomaterial, and the method comprises the following steps: firstly, mixing precursor salts of five elements of iridium, nickel, cobalt, copper and iron, adding the mixed precursor salts into graphene oxide, and preparing a solution, and then performing freeze drying to obtain a precursor powder; secondly, performing high-temperature calcination and decomposition on the precursor powder, and then performing high-energy ball milling to obtain a nanomixture; and thirdly, performing high-temperature calcination and oxidation on the nanomixture in air to obtain the iridium-nickel-cobalt-copper-iron high-entropy oxide nanomaterial. In the application, the precursor salts of the elements are loaded on the graphene oxide, the uniformly mixed precursor powder is obtained by combining freeze drying, the graphene oxide is removed by high-temperature calcination and decomposition, the elements are fully oxidized by ball milling and high-temperature calcination and oxidation, the iridium-nickel-cobalt-copper-iron high-entropy oxide nanomaterial with uniform elements and stability is obtained, the material has a very large specific surface area and a stable high-entropy oxide structure, and has application potential in the field of hydrogen production by water electrolysis.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of nanometer multi-element oxide preparation, and particularly relates to a preparation method of an iridium-nickel-cobalt-copper-iron high-entropy oxide nanomaterial. BACKGROUND

[0002] High-entropy materials are first proposed by Professor Ye Wucheng. People find that high-entropy materials combined with nanoparticles have very excellent physical and chemical properties because of the high-entropy alloy characteristics (high-entropy effect, atomic retardation diffusion effect, severe lattice distortion effect, cocktail effect and high-temperature stability effect) and the nanoparticle characteristics (surface and interface effect, small size effect, quantum size effect and macroscopic quantum tunneling effect).

[0003] Iridium-based high-entropy oxide nanomaterials have the diversity of components, the complexity of surface atomic structure, high mixing entropy and nanoscale effect, and thus exhibit excellent physical and chemical properties, and are expected to be used for water electrolysis hydrogen production anode oxygen evolution catalyst, and are concerned by a large number of researchers. At present, the preparation methods of iridium-based multi-element oxides mainly include powder metallurgy, mechanical alloying and calcination decomposition, and the prepared iridium-based multi-element oxides are limited to three elements, and it is difficult to synthesize iridium-based high-entropy oxide nanomaterials. This is because it is difficult to simultaneously decompose and oxidize more than five elements and form a high-entropy structure, and each element is uniformly distributed in the nanometer structure. Therefore, there are still great challenges in the preparation of iridium-based high-entropy oxide nanomaterials.

[0004] The patent with the publication number CN113430569A discloses an iridium oxide nanowire with a high aspect ratio and a preparation method of a water electrolysis membrane electrode thereof, which comprises the following steps: (1) uniformly mixing and grinding potassium carbonate powder and iridium powder to obtain a mixed powder; (2) heat-treating the mixed powder obtained in step (1) to obtain a black product, and after acid washing and water washing of the black product, an iridium oxide nanowire is obtained. The iridium oxide nanowire prepared by the method has a length of tens to hundreds of microns, is more suitable for a rough porous titanium current collector in a water electrolyzer, and can improve the utilization rate of noble metals of the nanowire electrode and the stability under high current density. Although the method synthesizes an iridium oxide nanowire, the method is not suitable for preparing an iridium-based high-entropy oxide nanomaterial.

[0005] The patent with publication number CN111545767A discloses a preparation method of nanoscale multi-element alloy. The method prepares a series of high-entropy alloy nanoparticles, including the following steps: one, adding the precursor into ultrapure water to prepare a precursor steady-state solution; two, spray drying the precursor steady-state solution to obtain a precursor powder; three, calcining the precursor powder to obtain nanoscale multi-element alloy. The method sprays and calcines the precursor steady-state solution, so that the metals in the nanoparticles are uniformly distributed, forming a single-phase solid solution structure or a two-phase structure, and obtaining nanoscale multi-element alloy or high-entropy alloy nanoparticles composed of fourteen metals in any combination and having a porous structure. Although the method can systematically prepare high-entropy alloy nanoparticles and also contains iridium-based high-entropy alloy, the high-entropy alloy nanoparticles have several structures and do not form a nanoskeleton structure, and the phase of the product is not easy to control. At the same time, it is not suitable for the preparation of iridium-based high-entropy oxide.

[0006] The patent with publication number CN111054378A discloses a high-entropy oxide type electrocatalytic anode oxygen evolution catalyst material and its preparation method, belonging to the field of functional materials. The patent uses an alloying ball milling method to prepare a high-entropy spinel oxide catalyst that can be used for electrocatalytic anode oxygen evolution reaction catalysis. It is a single spinel structure with uniform grain distribution and no second phase. The specific method is as follows: the required raw materials are MnO, CoO, NiO, and Fe3O4 powder. Four kinds of oxide powders are weighed according to the set molar ratio of each element, and the weighed powder is poured into a ball mill tank. After setting the parameters of the ball mill, alloying ball milling is performed to obtain a new high-entropy spinel oxide with a CoFe2O4 spinel structure. Although the method prepares high-entropy oxides, the distribution of each element in the nanomaterial is not uniform due to only ball milling, so the structure of the prepared high-entropy oxides is also diverse. At the same time, this preparation method is not suitable for the preparation of iridium-based high-entropy oxide nanomaterials. SUMMARY

[0007] The technical problem to be solved by the present application is to provide a preparation method of iridium-nickel-cobalt-copper-iron high-entropy oxide nanomaterials to solve the above-mentioned problems of the prior art. The method uses graphene oxide to load precursor salts of each element, combines freeze-drying to obtain a well-mixed precursor powder, then uses high-temperature calcination to decompose and remove graphene oxide, combines ball milling to promote the mixing of each atom, and exposes the unoxidized part, and then realizes full oxidation through high-temperature calcination to obtain an iridium-nickel-cobalt-copper-iron high-entropy oxide nanomaterial with uniform elements and stable structure, solving the preparation problems of iridium-based high-entropy oxide nanomaterials such as uneven composition and difficult to control phase.

[0008] To solve the above technical problems, the technical solution adopted by the present application is: a preparation method of iridium-nickel-cobalt-copper-iron high-entropy oxide nanomaterials, characterized in that the method comprises the following steps:

[0009] Step one, the precursor salt of five elements of iridium, nickel, cobalt, copper, iron is mixed, then graphene oxide is added and prepared into a solution, and then freeze-drying is carried out to obtain a precursor powder;

[0010] Step two, the precursor powder obtained in step one is subjected to high-temperature calcination and decomposition in air to obtain a nano-oxide powder, and then the nano-oxide powder is subjected to high-energy ball milling to obtain a mixed nano-mixture;

[0011] Step three, the nano-mixture obtained in step two is subjected to high-temperature calcination and oxidation in air to obtain an iridium-nickel-cobalt-copper-iron high-entropy oxide nano-material.

[0012] In the present application, the precursor salt of five elements in the target product and graphene oxide are first prepared into a uniform solution. Since the surface of graphene oxide has a large number of oxygen-containing functional groups, it has good hydrophilicity and is easily dispersed in water. By loading and dispersing each precursor salt through highly dispersed graphene oxide, the uniformity of each element in the solution is ensured. Combined with the freeze-drying process, each precursor salt is dried in situ on the surface of graphene oxide, so that each precursor salt is uniformly dispersed on the surface of graphene oxide to obtain a graphene oxide-loaded precursor powder, ensuring the uniform distribution of each element in the precursor powder, which is beneficial to the formation of high-entropy oxides in the later calcination. Then, the graphene oxide-loaded precursor powder is subjected to high-temperature calcination and decomposition in air. The graphene oxide in the powder reacts with air at high temperature to form carbon dioxide and volatilize, forming a nano-particle oxide powder, ensuring the complete removal of carbon materials. The nano-oxide particles are then subjected to high-energy ball milling to ensure the uniform mixing of each atom in the oxide powder and expose the unoxidized part inside. Finally, high-temperature calcination and oxidation are carried out in air to fully oxidize the unoxidized part, obtaining an iridium-nickel-cobalt-copper-iron high-entropy oxide nano-material with uniform elements. The material has a very large specific surface area and a stable high-entropy oxide structure, and has application potential in the field of water electrolysis hydrogen production.

[0013] The above-mentioned preparation method of an iridium-nickel-cobalt-copper-iron high-entropy oxide nano-material, characterized in that, in step one, the atomic ratio of the five elements of iridium, nickel, cobalt, copper and iron is 1:1:1:1:1, the mass of graphene oxide is 30% to 70% of the total mass of the five elements of iridium, nickel, cobalt, copper and iron, and the solution is prepared according to a proportion of 500 mL of water corresponding to 1 g of the total mass of the five elements of iridium, nickel, cobalt, copper and iron. By controlling the mass of graphene oxide and the preparation proportion of the solution, the present application ensures that each precursor salt is uniformly distributed on the surface of graphene oxide, avoiding the aggregation and segregation of nano-particles obtained by subsequent high-temperature calcination and decomposition, and providing a guarantee for the preparation of an iridium-nickel-cobalt-copper-iron high-entropy oxide nano-material.

[0014] The preparation method of the iridium-nickel-cobalt-copper-iron high-entropy oxide nanomaterial has the advantages that: the temperature of the freeze drying in the first step is-15℃ to-30℃, the vacuum degree is 5Pa to 15Pa, and the processing time is 10h to 20h.

[0015] The preparation method of the iridium-nickel-cobalt-copper-iron high-entropy oxide nanomaterial has the advantages that: the temperature of the high-temperature calcination and decomposition in the second step is 600℃ to 900℃, the time is 0.5h to 2h; and the rotation speed of the high-energy ball milling is 300r / min to 600r / min, and the time is 0.5h to 2h.

[0016] The preparation method of the iridium-nickel-cobalt-copper-iron high-entropy oxide nanomaterial has the advantages that: the temperature of the high-temperature calcination and decomposition in the second step is 600℃ to 900℃, the time is 0.5h to 2h; and the rotation speed of the high-energy ball milling is 300r / min to 600r / min, and the time is 0.5h to 2h.

[0017] Compared with the prior art, the present application has the following advantages:

[0018] 1. The present application first uses graphene oxide to load the precursor salts of the elements, combines freeze drying to obtain mixed precursor powder, then removes the graphene oxide by high-temperature calcination and decomposition, combines ball milling to promote the mixing of the atoms and expose the unoxidized parts, and then realizes full oxidation by high-temperature calcination and oxidation to obtain an iridium-nickel-cobalt-copper-iron high-entropy oxide nanomaterial with uniform elements and stability, which has a very large specific surface area and a stable high-entropy oxide structure and has application potential in the field of hydrogen production by water electrolysis.

[0019] 2. The iridium-nickel-cobalt-copper-iron high-entropy oxide nanomaterial prepared by the present application has a high-entropy oxide nanostructure, and the particle size of the nanoparticles is 10nm to 100nm, so that the structure and performance stability are improved.

[0020] 3. The preparation method of the present application is simple, easy to implement, green and environmentally friendly, and suitable for industrial production.

[0021] The technical solutions of the present application will be further described in detail below with reference to the drawings and examples. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 This invention provides a process flow for preparing iridium-nickel-cobalt-copper-iron high-entropy oxide nanomaterials.

[0023] Figure 2 This is a TEM image of the iridium-nickel-cobalt-copper-iron high-entropy oxide nanomaterial prepared in Example 1 of the present invention. Detailed Implementation

[0024] Example 1

[0025] like Figure 1 As shown, this embodiment includes the following steps:

[0026] Step 1: Mix the precursor salts of five elements (iridium, nickel, cobalt, copper, and iron) in an atomic ratio of 1:1:1:1:1. Then add graphene oxide, with the mass of graphene oxide being 70% of the total mass of the five elements. Prepare a solution by mixing 1g of each element with a ratio of 500mL of water. Then freeze-dry the solution at -30℃, under a vacuum of 15Pa, for 10 hours to obtain the precursor powder.

[0027] Step 2: The precursor powder obtained in Step 1 is calcined and decomposed in air at a high temperature of 600℃ for 0.5h to obtain nano-oxide powder. Then, the nano-oxide powder is subjected to high-energy ball milling at a speed of 300r / min for 0.5h to obtain a homogeneous nano-mixture.

[0028] Step 3: The nano-mixture obtained in Step 2 is subjected to high-temperature calcination oxidation in air at a temperature of 400℃ for 0.5h to obtain iridium-nickel-cobalt-copper-iron high-entropy oxide nanomaterials.

[0029] Testing revealed that the iridium-nickel-cobalt-copper-iron high-entropy oxide nanomaterials prepared in this embodiment have a nanostructure, and the particle size of the nanoparticles ranges from 10 nm to 100 nm.

[0030] Figure 2 These are TEM images of the iridium-nickel-cobalt-copper-iron high-entropy oxide nanomaterials prepared in this embodiment. Figure 2 It can be seen that the iridium-nickel-cobalt-copper-iron high-entropy oxide nanomaterial has a nanostructure, and the nanoparticles are no larger than 100 nm.

[0031] Example 2

[0032] like Figure 1 As shown, this embodiment includes the following steps:

[0033] Step one, the precursor salt of five elements of iridium, nickel, cobalt, copper and iron is mixed according to the atomic ratio of five elements of iridium, nickel, cobalt, copper and iron is 1:1:1:1:1, then add graphene oxide, the mass of graphene oxide is 50% of the total mass of five elements of iridium, nickel, cobalt, copper and iron, and prepare a solution according to the proportion of 1g of five elements of iridium, nickel, cobalt, copper and iron corresponding to 500mL water, then freeze-drying, the temperature of freeze-drying is-15℃, the vacuum degree is 5Pa, the processing time is 20h, the precursor powder is obtained;

[0034] Step two, the precursor powder obtained in step one is high-temperature calcined and decomposed in air, the temperature of high-temperature calcination and decomposition is 700℃, the time is 0.5h, the nano-oxide powder is obtained, then the nano-oxide powder is high-energy ball milled, the rotating speed of high-energy ball milling is 300r / min, the time is 0.5h, the mixed nano-mixture is obtained;

[0035] Step three, the nano-mixture obtained in step two is high-temperature calcined and oxidized in air, the temperature of high-temperature calcination and oxidation is 400℃, the time is 0.5h, the iridium-nickel-cobalt-copper-iron high-entropy oxide nano-material is obtained.

[0036] It is detected that the iridium-nickel-cobalt-copper-iron high-entropy oxide nano-material prepared in this embodiment is nano structure, and the particle size of nano-particle is 20nm-80nm.

[0037] Example 3

[0038] As shown in the following steps are included in this embodiment: Figure 1

[0039] Step one, the precursor salt of five elements of iridium, nickel, cobalt, copper and iron is mixed according to the atomic ratio of five elements of iridium, nickel, cobalt, copper and iron is 1:1:1:1:1, then add graphene oxide, the mass of graphene oxide is 30% of the total mass of five elements of iridium, nickel, cobalt, copper and iron, and prepare a solution according to the proportion of 1g of five elements of iridium, nickel, cobalt, copper and iron corresponding to 500mL water, then freeze-drying, the temperature of freeze-drying is-15℃, the vacuum degree is 5Pa, the processing time is 12h, the precursor powder is obtained;

[0040] Step two, the precursor powder obtained in step one is high-temperature calcined and decomposed in air, the temperature of high-temperature calcination and decomposition is 700℃, the time is 1h, the nano-oxide powder is obtained, then the nano-oxide powder is high-energy ball milled, the rotating speed of high-energy ball milling is 400r / min, the time is 1.5h, the mixed nano-mixture is obtained;

[0041] ​Step three, the nanometer mixture obtained in step two is subjected to high-temperature calcination oxidation in air, the temperature of high-temperature calcination oxidation is 500℃, and the time is 0.5h, to obtain the iridium-nickel-cobalt-copper-iron high-entropy oxide nanomaterial.

[0042] It is detected that the iridium-nickel-cobalt-copper-iron high-entropy oxide nanomaterial prepared in the embodiment is of a nano structure, and the particle size of the nanoparticles is 20nm-130nm.

[0043] Embodiment 4

[0044] As shown in the embodiment, the following steps are included: Figure 1

[0045] Step one, precursor salts of iridium, nickel, cobalt, copper and iron are mixed according to the atomic ratio of iridium, nickel, cobalt, copper and iron being 1:1:1:1:1, and graphene oxide is added, the mass of graphene oxide is 50% of the total mass of iridium, nickel, cobalt, copper and iron, and a solution is prepared according to the proportion of 1g of iridium, nickel, cobalt, copper and iron to 500mL of water, and then freeze-drying is performed, the temperature of freeze-drying is-20℃, the vacuum degree is 10Pa, and the processing time is 10h, to obtain a precursor powder;

[0046] Step two, the precursor powder obtained in step one is subjected to high-temperature calcination decomposition in air, the temperature of high-temperature calcination decomposition is 900℃, and the time is 0.5h, to obtain a nanometer oxide powder, and then high-energy ball milling is performed on the nanometer oxide powder, the rotating speed of high-energy ball milling is 600r / min, and the time is 2h, to obtain a mixed nanometer mixture;

[0047] Step three, the nanometer mixture obtained in step two is subjected to high-temperature calcination oxidation in air, the temperature of high-temperature calcination oxidation is 700℃, and the time is 2h, to obtain the iridium-nickel-cobalt-copper-iron high-entropy oxide nanomaterial.

[0048] It is detected that the iridium-nickel-cobalt-copper-iron high-entropy oxide nanomaterial prepared in the embodiment is of a nano structure, and the particle size of the nanoparticles is 50nm-150nm.

[0049] Embodiment 5

[0050] As shown in the embodiment, the following steps are included: Figure 1

[0051] ​​Step one, the precursor salt of five elements of iridium, nickel, cobalt, copper and iron is mixed according to the atomic ratio of the five elements of iridium, nickel, cobalt, copper and iron being 1:1:1:1:1, then graphene oxide is added, the mass of graphene oxide is 70% of the total mass of the five elements of iridium, nickel, cobalt, copper and iron, and the solution is prepared according to the proportion of 1g of the five elements of iridium, nickel, cobalt, copper and iron to 500mL of water, then freeze-drying is carried out, the temperature of freeze-drying is-15℃, the vacuum degree is 14Pa, and the processing time is 15h, to obtain a precursor powder;

[0052] Step two, the precursor powder obtained in step one is subjected to high-temperature calcination and decomposition in air, the temperature of high-temperature calcination and decomposition is 600℃, the time is 2h, to obtain a nano-oxide powder, then the nano-oxide powder is subjected to high-energy ball milling, the rotation speed of high-energy ball milling is 600r / min, the time is 2h, to obtain a mixed nano-mixture;

[0053] Step three, the nano-mixture obtained in step two is subjected to high-temperature calcination and oxidation in air, the temperature of high-temperature calcination and oxidation is 500℃, the time is 0.5h, to obtain an iridium-nickel-cobalt-copper-iron high-entropy oxide nano-material.

[0054] It is detected that the iridium-nickel-cobalt-copper-iron high-entropy oxide nano-material prepared in the embodiment is of nano structure, and the particle size of the nano-particles is 10nm-80nm.

[0055] The above is only a preferred embodiment of the present application, and does not limit the present application. Any simple modification, change and equivalent change made according to the technical essence of the present application to the above embodiment are still within the protection scope of the technical solution of the present application.

Claims

1. A preparation method of an iridium-nickel-cobalt-copper-iron high-entropy oxide nanomaterial, characterized in that, The method comprises the following steps: Step one, mixing the precursor salts of iridium, nickel, cobalt, copper and iron, then adding graphene oxide and preparing a solution, and then freeze-drying to obtain a precursor powder; Step two, high-temperature calcination decomposition of the precursor powder obtained in step one in air to obtain a nano-oxide powder, and then high-energy ball milling of the nano-oxide powder to obtain a uniformly mixed nano-mixture; Step three, high-temperature calcination oxidation of the nano-mixture obtained in step two in air to obtain an iridium-nickel-cobalt-copper-iron high-entropy oxide nano-material.

2. The method for preparing an iridium-nickel-cobalt-copper-iron high-entropy oxide nanomaterial according to claim 1, characterized in that, In step one, the atomic ratio of the five elements of iridium, nickel, cobalt, copper and iron is 1:1:1:1:1, the mass of the graphene oxide is 30% to 70% of the total mass of the five elements of iridium, nickel, cobalt, copper and iron, and the solution is prepared according to a proportion of 500 mL of water corresponding to 1 g of the total mass of the five elements of iridium, nickel, cobalt, copper and iron.

3. The method for preparing an iridium-nickel-cobalt-copper-iron high-entropy oxide nanomaterial according to claim 1, characterized in that, In step one, the temperature of the freeze-drying is -15℃ to -30℃, the vacuum degree is 5Pa to 15Pa, and the processing time is 10h to 20h. 4.The preparation method of the iridium-nickel-cobalt-copper-iron high-entropy oxide nanomaterial according to claim 1, characterized in that, In step two, the high-temperature calcination decomposition temperature is 600℃ to 900℃, the time is 0.5h to 2h, the high-energy ball milling speed is 300r / min to 600r / min, and the time is 0.5h to 2h. 5.The preparation method of the iridium-nickel-cobalt-copper-iron high-entropy oxide nanomaterial according to claim 1, characterized in that, In step three, the high-temperature calcination oxidation temperature is 400℃ to 700℃, and the time is 0.5h to 2h.

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