Monatomic metal doped defect Co3O4 material as well as preparation method and application thereof

Abstract

The invention relates to a monatomic metal doped defect Co3O4 material as well as a preparation method and application thereof. The preparation method of the monatomic metal doped defect Co3O4 material comprises the following steps: carrying out ball milling and separation on Co3O4 and a metal sheet to obtain the monatomic metal doped defect Co3O4 material, the metal sheet is a molybdenum sheet or a combination of the molybdenum sheet, a nickel sheet, an iron sheet, a tantalum sheet and a tungsten sheet; the ball milling time is 0.8-2.5 hours, and the rotating speed is 300-400 rpm (revolutions per minute). According to the preparation method, Co3O4 and a specific metal sheet are subjected to ball milling, meanwhile, the ball milling time and the rotating speed are regulated and controlled, and the obtained monatomic metal doped defect Co3O4 material has good OER catalytic performance.

Description

Technical Field

[0001] The present invention relates to the field of catalyst technology, and more specifically, to a single-atom metal-doped defect Co3O4 material and a preparation method and application thereof. Background Art

[0002] As people's demand for energy continues to increase, in order to prevent the further deterioration of climate problems, it is imperative to use renewable energy to reduce dependence on traditional fossil energy and reduce carbon emissions. H2 has the advantages of environmental friendliness and high energy density. It can be used as an ideal new energy carrier to replace fossil fuels and can be produced by water electrolysis. Using electricity to decompose water into hydrogen and oxygen is one of the most promising methods for preparing H2. The process of water electrolysis includes two parts: cathode hydrogen evolution reaction (HER) and anode oxygen evolution reaction (OER). The development of efficient oxygen evolution reaction catalysts is crucial to improving the efficiency of hydrogen production by water electrolysis.

[0003] At present, the materials with excellent OER electrocatalytic activity mainly include precious metal materials such as IrO2 and RuO2. For example, a Chinese patent entitled "Ru / RuO2 / MoO2 composite material and its preparation method and application" uses precious metal materials. However, these materials are expensive, and Ru 4+ Easily oxidized to Ru at high anodic potential 8+ , poor stability.

[0004] As a special oxide with AB2O4 structure, spinel not only has the advantages of low cost and environmental friendliness, but also has the characteristics of flexible composition and valence state and stable existence in alkaline solution. Co3O4 is the easiest Co-based spinel to synthesize, which has certain electrocatalytic OER potential. However, studies have shown that the OER electrocatalytic activity of pure Co3O4 is poor, which limits its application in oxygen evolution reaction in water electrolysis.

[0005] The above-mentioned, it is of great significance to develop new technologies to improve the OER electrocatalytic activity of Co3O4 materials so that they can be widely used in oxygen evolution in water electrolysis. Summary of the invention

[0006] The primary purpose of the present invention is to overcome the poor OER electrocatalytic activity of the existing pure Co3O4 and provide a method for preparing a single-atom metal-doped Co3O4 material. The preparation method ball-mills Co3O4 and a specific metal sheet while regulating the ball-milling time and speed, and the obtained single-atom metal-doped Co3O4 material has good OER catalytic performance.

[0007] A further object of the present invention is to provide a single-atom metal-doped defect Co3O4 material.

[0008] A further object of the present invention is to provide the use of the above-mentioned single-atom metal-doped defect Co3O4 material as a catalyst in the oxygen evolution reaction of water electrolysis.

[0009] The above-mentioned object of the present invention is achieved by the following technical solutions:

[0010] A method for preparing a single-atom metal-doped defective Co3O4 material comprises the following steps:

[0011] Ball milling and separation of Co3O4 and metal sheets are performed to obtain the single-atom metal-doped defective Co3O4 material;

[0012] The metal sheet is a molybdenum sheet, or a combination of a molybdenum sheet, a nickel sheet, an iron sheet, a tantalum sheet and a tungsten sheet;

[0013] The ball milling time is 0.8 to 2.5 hours, and the rotation speed is 300 to 400 rpm.

[0014] The inventors of the present invention have found that by ball milling Co3O4 and a specific metal sheet together, and regulating the time and speed of ball milling, the single-atom metal-doped defect Co3O4 material obtained has good OER catalytic performance, which is specifically manifested as: having a high current peak in the cyclic voltammetry test and a small impedance value in the electrochemical impedance spectrum. The reason is: on the one hand, the mechanical force of ball milling causes the surface of Co3O4 to deform significantly, forming a large number of vacancy defect sites; on the other hand, the metal single atoms worn off the molybdenum sheet (when the metal sheet is a molybdenum sheet) during the ball milling process occupy the vacancy defect sites, forming single-atom doping; the combined effect of the two aspects obtains the single-atom metal-doped defect Co3O4 material, and due to the doping of the single-atom metal, the material has good OER catalytic performance. In addition, the formation of a large number of vacancy defect sites leads to the increase of the interlayer spacing, and the abundant vacancies generated during the ball milling process will cause the electrons between neighboring atoms to be rearranged, thereby improving the conductivity of the material.

[0015] In addition, when the metal sheet is a combination of molybdenum, nickel, iron, tantalum and tungsten sheets, metal single atoms can also occupy vacancy defect sites to form single atom doping, and the result is a high-entropy single atom metal-doped defect Co3O4 material.

[0016] The selection of a specific type of metal flake is critical, as it not only facilitates the separation of samples after ball milling (after ball milling, the single-atom metal-doped defective Co3O4 material is in powder form, while the metal flake still exists in a flake form, so it is easy to separate the powdered sample and the metal flake, thereby obtaining the single-atom metal-doped defective Co3O4 material), but also prevents the metal flake from producing metal element powders due to ball milling, thereby preventing the metal element powders from being mixed into the single-atom metal-doped defective Co3O4 material by physical mixing, thereby ensuring the catalytic performance of the material. If metal powders are added instead of metal flakes, the single-atom metal-doped defective Co3O4 material after ball milling separation will be mixed with metal element powders that are difficult to obtain, which will cause the catalytic performance of the material to deteriorate; if the type of metal flake selected is not appropriate, metal element powders may be produced during the ball milling process, thereby being mixed into the Co3O4 material, causing the catalytic performance of the material to deteriorate.

[0017] Preferably, the mass fraction of the single-atom metal in the single-atom metal-doped defective Co3O4 material is 0.8-1.2%, and specifically can be 0.80%, 0.82%, 0.85%, 0.88%, 0.90%, 0.95%, 0.98%, 1.00%, 1.05%, 1.10%, 1.15% or 1.20%.

[0018] More preferably, the monatomic metal is monatomic molybdenum and monatomic iron, or monatomic molybdenum, monatomic nickel, monatomic iron, monatomic tantalum and monatomic tungsten.

[0019] When the monatomic metals are monatomic molybdenum and monatomic iron, the mass ratio of monatomic molybdenum to monatomic iron is 1:(1.5-4).

[0020] When the monatomic metal is monatomic molybdenum, monatomic nickel, monatomic iron, monatomic tantalum and monatomic tungsten, the mass ratio of monatomic molybdenum, monatomic nickel, monatomic iron, monatomic tantalum and monatomic tungsten is 1:(1.6~4.2):(1.5~4):(2~5):(2~5).

[0021] Preferably, the Co3O4 is powdered Co3O4.

[0022] Preferably, the ball milling is carried out in a ball milling tank of a ball mill.

[0023] The key to the present invention is that the molybdenum metal single atoms of the molybdenum sheet are doped into Co3O4 during the ball milling process, so Co3O4 needs to contact the molybdenum sheet during the ball milling process. The material of the surrounding inner wall of the ball milling jar and the ball milling beads is usually iron, so the iron metal single atoms are inevitably doped during the ball milling process. Co3O4 can contact the surrounding inner wall of the ball milling jar or not.

[0024] More preferably, during the ball milling process, Co3O4 is in contact with the metal sheet.

[0025] Further preferably, during the ball milling process, Co3O4 does not contact the inner walls of the ball mill.

[0026] Further preferably, the metal sheet surrounds the inner wall of the ball mill.

[0027] In order to reduce the doping of single iron metal atoms as much as possible, metal sheets can be placed around the inner walls of the ball mill so that Co3O4 does not contact the inner walls of the ball mill.

[0028] Preferably, the ball milling beads used in the ball milling are iron balls.

[0029] Further preferably, the amount of Co3O4 used is 3 to 5 g.

[0030] Preferably, the separation further includes the steps of filtration and drying.

[0031] Preferably, the ball milling is dry ball milling or wet ball milling.

[0032] More preferably, the ball milling is dry ball milling.

[0033] Preferably, the ball milling time is 0.8 to 2 hours.

[0034] Preferably, the ball milling time is 0.8 to 1 hour. By adjusting the ball milling time within this range, the agglomeration of the Co3O4 material caused by a longer ball milling time can be reduced, thereby improving the catalytic performance of the Co3O4 material.

[0035] Preferably, the rotation speed of the ball mill is 300 to 320 rpm. By adjusting the rotation speed of the ball mill within a suitable range, the crushing and squeezing effect of the ball mill on Co3O4 can be further improved, which is more conducive to the formation of metal single atom doped vacancy defects and further improves the catalytic performance.

[0036] Preferably, the thickness of the metal sheet is 0.2-2 mm.

[0037] When the metal sheet is a combination of molybdenum sheet, nickel sheet, iron sheet, tantalum sheet and tungsten sheet, the area ratio of the molybdenum sheet, nickel sheet, iron sheet, tantalum sheet and tungsten sheet is 1:1:1:1:1, and Co3O4 is in direct contact with each metal sheet but not with the inner wall around the ball mill. In this case, a high-entropy single-atom metal-doped defect Co3O4 material can be obtained.

[0038] Preferably, the metal sheet is a molybdenum sheet. Only molybdenum sheets are selected, so that the single-atom metal of the single-atom metal-doped defective Co3O4 material obtained is mainly molybdenum, and the catalytic performance of the material is better. Specifically, only molybdenum sheets are selected, and the current peak value of the single-atom metal-doped defective Co3O4 material obtained in the cyclic voltammetry test is about 0.12A, which is about 3 times that of pure Co3O4.

[0039] Preferably, after ball milling and before separation, a calcination step is also included. The calcination treatment can further disperse the atoms of the atomic metal-doped defective Co3O4 material, and the metal single atom sites can form a more stable coordination structure after high-temperature calcination, while eliminating other non-coordinated heteroatoms, and the catalytic performance of the material is better.

[0040] More preferably, the burning temperature is 680-720° C. and the burning time is 0.8-1.2 h.

[0041] A single-atom metal-doped defect Co3O4 material is prepared by the above preparation method.

[0042] The use of the above-mentioned single-atom metal-doped defective Co3O4 material as a catalyst in the oxygen evolution reaction of water electrolysis is also within the protection scope of the present invention.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] The preparation method of the present invention ball-mills Co3O4 and a specific metal sheet, and simultaneously regulates the time and rotation speed of the ball milling to obtain a single-atom metal-doped defect Co3O4 material, which has good OER catalytic performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 Schematic diagram of the placement of metal molybdenum sheets in a ball mill according to the preparation method of Example 1.

[0046] Figure 2 The X-ray diffraction test results of the samples of Example 1 and Comparative Example 1 are shown.

[0047] Figure 3 The scanning electron microscope images of the samples of Example 1, Example 4 and Comparative Example 2 are shown.

[0048] Figure 4 Transmission electron microscope images of the samples of Example 1 and Example 4.

[0049] Figure 5 This is the element distribution diagram of the sample of Example 4.

[0050] Figure 6It is the line distribution curve of the element content change of the sample of Example 4.

[0051] Figure 7 This is the element distribution diagram of the sample of Example 1.

[0052] Figure 8 This is the line distribution curve of the element content change of the sample in Example 1.

[0053] Fig. 9 This is the EPR diagram of the sample of Example 1.

[0054] Fig.10 This is the EPR diagram of the sample of Example 5.

[0055] Fig.11 This is the EPR diagram of the sample of Example 6.

[0056] Fig.12 This is the EPR diagram of the sample of Comparative Example 1.

[0057] Fig.13 This is the EPR diagram of the sample of Comparative Example 2.

[0058] Fig.14 This is the cyclic voltammogram of the sample of Example 1.

[0059] Fig.15 This is the cyclic voltammogram of the sample of Example 5.

[0060] Fig.16 This is the cyclic voltammogram of the sample of Example 6.

[0061] Fig.17 This is the cyclic voltammogram of the sample of Comparative Example 1.

[0062] Fig.18 This is the cyclic voltammogram of the sample of Comparative Example 2.

[0063] Fig.19 The flow impedance spectrum test result diagram of the samples of Example 1, Example 5, Example 6, Comparative Example 1 and Comparative Example 2 is shown. DETAILED DESCRIPTION

[0064] In order to more clearly and completely describe the technical solution of the present invention, the present invention is further described in detail through specific embodiments below. It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention. Various changes can be made within the scope of the rights of the present invention.

[0065] Example 1

[0066] This embodiment provides a method for preparing a single-atom metal-doped defective Co3O4 material, comprising the following steps:

[0067] 3g of cobalt trioxide (Aladdin, AR, the same below), metal molybdenum flakes and iron balls (5 large balls, diameter d=1.5cm; 20 medium balls, diameter d=1cm; 50 small balls, diameter d=5mm) were placed in a ball mill (planetary ball mill, Hunan Changsha Miqi MITR Instrument Co., Ltd.), wherein the metal molybdenum flakes were surrounded by the inner wall of the ball mill so that the cobalt trioxide and the iron balls were in contact with the metal molybdenum flakes, but not with the inner wall of the ball mill body. Figure 1 As shown; dry grinding was performed at 300 rpm for 1 hour, and then the ball mill was rinsed with distilled water, filtered and dried to obtain a powdered sample, thereby obtaining a single-atom metal-doped defect Co3O4 material.

[0068] Example 2

[0069] This embodiment provides a method for preparing a single-atom metal-doped defective Co3O4 material, comprising the following steps:

[0070] 3g of cobalt trioxide, metal molybdenum sheet and iron balls (5 large balls with d=1.5cm, 20 medium balls with d=1cm, 50 small balls with d=5mm) were placed in a ball mill, wherein the metal molybdenum sheet was surrounded by the inner wall of the ball mill so that the cobalt trioxide and the iron balls were in contact with the metal molybdenum sheet but not with the inner wall of the ball mill. Dry milling was performed at 300rpm for 2 hours, and then the ball mill was rinsed with distilled water, filtered and dried to obtain a powdered sample, i.e., a single-atom metal-doped defect Co3O4 material was obtained.

[0071] Example 3

[0072] This embodiment provides a method for preparing a single-atom metal-doped defective Co3O4 material, comprising the following steps:

[0073] 3g of cobalt tetraoxide, metal molybdenum flakes and iron balls (5 large balls with d=1.5cm, 20 medium balls with d=1cm, 50 small balls with d=5mm) were placed in a ball mill, wherein the metal molybdenum flakes were surrounded by the inner wall of the ball mill so that the cobalt tetraoxide and the iron balls were in contact with the metal molybdenum flakes, but not with the inner wall of the ball mill. Dry milling was performed at 400rpm for 1 hour, and then the ball mill was rinsed with distilled water, filtered and dried to obtain a powdered sample, that is, a single-atom metal-doped defect Co3O4 material was obtained.

[0074] Example 4

[0075] This embodiment provides a method for preparing a single-atom metal-doped defective Co3O4 material, comprising the following steps:

[0076] 3g of cobalt tetraoxide, metal molybdenum sheet and iron balls (5 large balls with d=1.5cm, 20 medium balls with d=1cm, 50 small balls with d=5mm) were placed in a ball mill, wherein the metal molybdenum sheet surrounded the inner wall of the ball mill so that the cobalt tetraoxide and the iron balls were in contact with the metal molybdenum sheet, but not with the inner wall of the ball mill. Distilled water was added to the ball mill until the iron balls were covered, and then a small amount of ethanol was added, and wet milled at 300rpm for 1 hour, and then the ball mill was rinsed with distilled water, filtered and dried to obtain a powdered sample, that is, a single-atom metal-doped defect Co3O4 material was obtained.

[0077] Example 5

[0078] This embodiment provides a method for preparing a single-atom metal-doped defective Co3O4 material, comprising the following steps:

[0079] 3g of cobalt tetraoxide, metal molybdenum sheet, nickel sheet, iron sheet, tantalum sheet, tungsten sheet and iron balls (5 large balls with d=1.5cm, 20 medium balls with d=1cm, 50 small balls with d=5mm) are placed in a ball mill, wherein the metal molybdenum sheet, nickel sheet, iron sheet, tantalum sheet and tungsten sheet are cut to an area ratio of about 1:1:1:1:1, spliced ​​together to form a metal sheet and closely attached to the inner wall of the ball mill, so that the cobalt tetraoxide and the iron ball are in contact with the metal sheet, but not with the inner wall of the ball mill. Distilled water is added to the ball mill until the iron ball is submerged, and then a small amount of ethanol is added, and then wet-milled at 300rpm for 2 hours, and then the ball mill is rinsed with distilled water, filtered and dried to obtain a powdered sample, that is, a single-atom metal-doped defect Co3O4 material is obtained.

[0080] Example 6

[0081] This embodiment provides a method for preparing a single-atom metal-doped defective Co3O4 material, which is basically the same as that of Embodiment 5, except that after obtaining the powdered sample, the powdered sample is calcined in an air atmosphere at 700°C for 1 hour.

[0082] Comparative Example 1

[0083] This comparative example provides a method for preparing a Co3O4 material, which is basically the same as Example 1, except that no molybdenum sheet is added.

[0084] Comparative Example 2

[0085] This comparative example provides pure cobalt tetroxide without any treatment, that is, the cobalt tetroxide in Example 1 before being put into the ball mill.

[0086] Sample characterization

[0087] 1. XRD characterization analysis

[0088] The product samples of Example 1 (Co3O4+Mo dry grinding for 1h) and Comparative Example 1 (Co3O4 dry grinding for 1h) were subjected to X-ray diffraction test. The results are as follows: Figure 2 As shown. Figure 2 It can be seen that the sample of Example 1 has characteristic diffraction peaks at 31.3° and 36.9°. The appearance of these two diffraction peaks shows that the single-atom metal-doped defect Co3O4 material prepared in Example 1 still has the original phase structure, indicating that ball milling has not changed the original crystal structure of Co3O4.

[0089] 2. SEM characterization analysis

[0090] The product samples of Example 1, Example 4 and Comparative Example 2 were scanned by scanning electron microscope. The results are as follows: Figure 3 As shown, Figure 3 A to C are high-magnification photos. Figure 3 D to F are low-magnification photos. Figure 3 A and Figure 3 Sample D is comparative example 2, Figure 3 B and Figure 3 The sample of E is Example 4, Figure 3 C and Figure 3 The sample of F is Example 1. Figure 3 It can be seen that the samples of Example 1 and Example 4 have a lamellar structure, which can expose specific index crystal planes and have a large surface area, and can provide more reactive sites and shorter ion diffusion channels, thereby enhancing the adsorption of active substances; at high magnification, it can be observed that their morphology is as loose as cotton candy, and there are also some pores with smaller pore sizes that penetrate the lamellar layers.

[0091] 3. TEM characterization analysis

[0092] The product samples of Example 1 and Example 4 were scanned by transmission electron microscope, and the results were as follows: Figure 4 As shown, Figure 4 A and Figure 4 C is the TEM image of the sample of Example 4 at different magnifications, Figure 4 B and Figure 4 D is a TEM image of the sample of Example 1 at different magnifications. Figure 4 It can be seen that the single-atom metal-doped defect Co3O4 material has a flake structure, which indicates that after ball milling, Co3O4 is well exfoliated.

[0093] 4. EDS characterization analysis

[0094] The product samples of Example 1 and Example 4 were tested by SEM-EDS. The results are as follows: Figures 5 to 8 As shown, Figure 5 is the element distribution diagram of the sample of Example 4, Figure 6 is the line distribution curve of the element content change of the sample of Example 4, Figure 7 is the element distribution diagram of the sample of Example 1, Figure 8 This is a line distribution curve of the element content change of the sample of Example 1.

[0095] The element mass contents of the samples of Example 1 and Example 4 are shown in Table 1.

[0096] Table 1

[0097] element Co Fe Mo O Example 1 content / % 68.34 0.71 0.45 30.50 Example 4 content / % 70.43 0.67 0.18 28.72

[0098] from Figures 5 to 8 As shown in Table 1, the unit metal Mo has been successfully doped into the Co3O4 material, which improves the catalytic performance of the material. Since iron balls are used in the ball milling process, iron elements also enter the Co3O4 material after ball milling.

[0099] 5. EPR characterization analysis

[0100] The samples of Example 1, Example 5, Example 6, Comparative Example 1 and Comparative Example 2 were subjected to EPR characterization analysis. The results are as follows: Figures 9 to 13 As shown, Fig. 9 is the EPR diagram of Example 1, Fig.10 is the EPR diagram of Example 5, Fig.11 is the EPR diagram of Example 6, Fig.12 is the EPR diagram of Comparative Example 1, Fig.13 This is the EPR diagram of Comparative Example 2. Fig. 9 and Fig.13 The intensity of the peak shows that Mo atoms can occupy oxygen vacancies, resulting in a reduction in oxygen vacancies and the formation of single-atom metal doping; Fig.10 and Fig.11 From the intensity of the peak, we can know that high-temperature calcination can increase the number of oxygen vacancies in the material and provide more active sites for the doping of single-atom metals.

[0101] Performance Testing

[0102] The samples of the embodiments and comparative examples were measured using an electrochemical workstation, and the process was as follows:

[0103] 1) Treat the nickel foam with appropriate amounts of anhydrous ethanol, sulfuric acid and distilled water (put the nickel foam and the cleaning solution used into a beaker and put it into an ultrasonic cleaning machine), take out the nickel foam after cleaning for 20 minutes and dry it.

[0104] 2) Take 0.005 g of sample in a test tube, add 100 μmL of Nafion water and 900 μmL of anhydrous ethanol, and ultrasonicate for 20 min to obtain a sample dispersion.

[0105] 3) Use a syringe to take 0.1 mL of sample dispersion and drop it on the nickel foam and then dry it.

[0106] 4) Connect the mercury-mercury oxide electrode, carbon rod, and working electrode (with nickel foam) to the electrochemical workstation (the electrolyte is KOH solution) and determine its CV5 and EIS curves after activation. (CV5 is the cyclic voltammogram with a scanning rate of 5mV / s).

[0107] The above method was used to test the samples of Example 1 (Co3O4+Mo dry grinding for 1 h), Example 5 (high entropy / Co3O4 wet grinding for 2 h), Example 6 (high entropy / Co3O4 wet grinding for 2 h followed by high temperature calcination treatment), Comparative Example 1 (Co3O4 dry grinding for 1 h) and Comparative Example 2 (pure Co3O4), and the results were as follows: Figures 14 to 18 As shown. Fig.14 , Fig.17 and Fig.18 It can be seen that after single-atom Mo doping, the current peak value of the material is significantly increased (the current peak value of Example 1 is 0.1197A), that is, the OER catalytic performance is significantly improved; Fig.15 and Fig.16 It can be seen that after high-temperature calcination, the current peak of the material is significantly increased, indicating that high-temperature calcination can improve the OER catalytic performance.

[0108] Electrochemical impedance spectroscopy (EIS) is also called electrochemical impedance spectroscopy. It measures the change of impedance with the frequency of a sine wave, and then analyzes the electrode process kinetics and diffusion mechanisms. The EIS results of the samples of Example 1, Example 5, Example 6, Comparative Example 1 and Comparative Example 2 are as follows: Fig.19 As shown. Fig.19 It can be seen that the impedance values ​​of each embodiment are small, indicating the conductivity of the single-atom metal-doped defect Co3O4 material of the present invention; among them, the impedance value of the sample of Example 1 is the smallest, indicating that its conductivity is the best. The impedance values ​​of the samples of Comparative Examples 1 and 2 are relatively large.

[0109] The single-atom metal-doped defect Co3O4 materials of Examples 2 and 3 also have good OER catalytic performance, and compared with Examples 2 and 3, the OER catalytic performance of Example 1 is better.

[0110] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A method for preparing a single-atom metal-doped defective Co3O4 material, characterized in that: The steps include: Ball milling and separation of Co3O4 and metal sheets are performed to obtain the single-atom metal-doped defective Co3O4 material; The metal sheet is a molybdenum sheet, or a combination of a molybdenum sheet, a nickel sheet, an iron sheet, a tantalum sheet and a tungsten sheet; The ball milling time is 0.8 to 2.5 hours, and the rotation speed is 300 to 400 rpm.

2. The preparation method according to claim 1, characterized in that: The ball milling is carried out in a ball milling jar.

3. The preparation method according to claim 3, characterized in that: The metal sheets surround the inner walls of the ball mill.

4. The preparation method according to claim 1, characterized in that: The separation further includes the steps of suction filtration and drying.

5. The preparation method according to claim 1, characterized in that: The ball milling is dry ball milling or wet ball milling.

6. The preparation method according to claim 1, characterized in that: The metal sheet is a molybdenum sheet.

7. The preparation method according to claim 1, characterized in that: After the ball milling and before the separation, a burning step is also included.

8. The preparation method according to claim 7, characterized in that: The burning temperature is 680-720° C. and the burning time is 0.8-1.2 h.

9. A single-atom metal-doped defective Co3O4 material, characterized in that: It is prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the single-atom metal-doped defect Co3O4 material according to claim 9 as a catalyst in the oxygen evolution reaction of water electrolysis.

Images