阅读说明：本技术 一种利用废弃三元镍钴锰酸锂制备高活性三元金属氧化物析氧催化剂的方法 (Method for preparing high-activity ternary metal oxide oxygen evolution catalyst by utilizing waste ternary nickel cobalt lithium manganate ) 是由 李虎林 李毅 蔡建荣 杜佳 郑成 王宇 魏海滨 杨霄 于 2020-12-29 设计创作，主要内容包括：本发明公开了一种利用废弃三元镍钴锰酸锂制备高活性三元金属氧化物析氧催化剂的方法,(1)将废弃三元镍钴锰酸锂正极材料过筛后筛下物磨成粉,放入稀盐酸中浸泡,取上清液记为A；(2)向A加入NaOH溶液,至溶液中性止,得B；(3)向B中加入十六烷基三甲基溴化铵,得C；(4)向C放入泡沫铜,以泡沫铜为工作电极,C为反应溶液,将泡沫铜侵泡在C溶液表面,氧气气氛下对泡沫铜等离子体放电,使其在表面快速发生化学反应；(5)将上述自支撑电极洗涤后干燥,即获得了高活性三元金属氧化物析氧催化剂。本发明方法简单,条件温和,可实现快速制备高活性析氧催化剂,制备的催化剂由纳米棒交错组成的三维网络状结构,催化剂性能稳定。(The invention discloses a method for preparing a high-activity ternary metal oxide oxygen evolution catalyst by utilizing waste ternary nickel cobalt lithium manganate, which comprises the following steps of (1) sieving a waste ternary nickel cobalt lithium manganate positive electrode material, grinding undersize into powder, soaking the powder in dilute hydrochloric acid, and taking supernatant liquid as A; (2) adding NaOH solution into the solution A until the solution is neutral to obtain B; (3) adding hexadecyl trimethyl ammonium bromide into the B to obtain C; (4) placing the foamy copper into the solution C, soaking the foamy copper on the surface of the solution C by taking the foamy copper as a working electrode and the solution C as a reaction solution, and discharging the foamy copper plasma in an oxygen atmosphere to enable the foamy copper plasma to rapidly generate a chemical reaction on the surface; (5) and washing and drying the self-supporting electrode to obtain the high-activity ternary metal oxide oxygen evolution catalyst. The method is simple, the conditions are mild, the high-activity oxygen evolution catalyst can be rapidly prepared, the prepared catalyst is in a three-dimensional network structure formed by the staggered nanorods, and the performance of the catalyst is stable.)

1. The method for preparing the high-activity ternary metal oxide oxygen evolution catalyst by utilizing the waste ternary nickel cobalt lithium manganate is characterized by sequentially carrying out the following steps:

(1) crushing and sieving the waste ternary nickel cobalt lithium manganate positive electrode material, taking undersize, grinding the undersize into powder, soaking the powder in dilute hydrochloric acid, and taking supernatant A;

(2) adding sodium hydroxide solution into the solution A until the pH value of the solution is 7 to obtain B;

(3) adding hexadecyl trimethyl ammonium bromide into the B to obtain C;

(4) placing foam copper with the diameter of 1cm multiplied by 1cm into the C, taking the foam copper as a working electrode and the C as a reaction solution, soaking the foam copper on the surface of the C solution, and simultaneously carrying out plasma discharge on the foam copper in an oxygen atmosphere to enable the surface of the foam copper to quickly and efficiently carry out chemical reaction;

(5) and (3) washing the self-supporting electrode for 3-6 times by using absolute ethyl alcohol and deionized water in sequence, and drying in vacuum to obtain the high-activity ternary metal oxide oxygen evolution catalyst.

2. The method for preparing the high-activity ternary metal oxide oxygen evolution catalyst by using the waste ternary nickel cobalt lithium manganate as claimed in claim 1, wherein in the step (1), the undersize is ground into powder with a particle size of 400 meshes.

3. The method for preparing the high-activity ternary metal oxide oxygen evolution catalyst by using the waste ternary nickel cobalt lithium manganate as claimed in claim 1, wherein in the step (1), the concentration of the dilute hydrochloric acid is 3-6M, and the soaking time is 10-15 h.

4. The method for preparing the high-activity ternary metal oxide oxygen evolution catalyst by using the waste ternary nickel cobalt lithium manganate as claimed in claim 1, wherein in the step (3), the concentration of the hexadecyl trimethyl ammonium bromide is 8-16 g/L.

5. The method for preparing a high-activity ternary metal oxide oxygen evolution catalyst by using waste ternary nickel cobalt lithium manganate as claimed in claim 1, wherein in the step (4), the plasma discharge voltage is 150V, and the reaction time is 180-300 s.

6. The method for preparing the high-activity ternary metal oxide oxygen evolution catalyst by using the waste ternary nickel cobalt lithium manganate as claimed in claim 1, wherein in the step (5), the drying temperature is 60-100 ℃, and the drying time is 6-12 h.

7. The method for preparing the high-activity ternary metal oxide oxygen evolution catalyst by using the waste ternary nickel cobalt lithium manganate as claimed in claim 1, wherein in the step (4), the thickness of the copper foam is 0.01 cm.

8. The method for preparing the high-activity ternary metal oxide oxygen evolution catalyst by using the waste ternary nickel cobalt lithium manganate as claimed in any one of claims 1 to 7, wherein the high-activity ternary metal oxide oxygen evolution catalyst is a three-dimensional network structure formed by the staggered nanorods, and the diameter of the nanorods is 100-200 nm.

Technical Field

The invention belongs to the field of waste resource utilization and catalytic chemistry, relates to a preparation method of a high-activity ternary metal oxide oxygen evolution catalyst applied to electrolyzed water, and particularly relates to a method for preparing the high-activity ternary metal oxide oxygen evolution catalyst by using waste ternary nickel cobalt lithium manganate.

Background

The electrolytic water reaction has important significance in the preparation of clean energy. In recent years, as a half reaction of the electrolytic water reaction, the Hydrogen Evolution Reaction (HER) has been developed rapidly; however, the slow kinetics of the other half-reaction, the Oxygen Evolution Reaction (OER), due to its complex four-electron process, is a bottleneck that limits the overall efficiency of the electrolytic water reaction. Electrocatalysts of high oxygen evolution activity have long been generally noble metals Ir, Ru-based materials. However, the rarity of these two elements determines the urgency to develop a rich-reserve transition group OER highly active catalyst. To this end, catalysts for OER reactions have undergone extensive research, such as oxides, hydroxides, phosphides, nitrides, and chalcogenides, to address these challenges. Therefore, the design of a non-noble metal catalyst with abundant resources and low cost is urgently needed.

The ternary nickel cobalt lithium manganate is a widely applied anode material of the lithium ion battery, and has higher specific capacity and lower cost than a unit anode material. However, with the large amount of use and the limited service life, the lithium ion battery after being retired is bound to be subjected to recycling. In order to recycle and utilize the waste resource, simple treatment according to hazardous waste is avoided. The method has the advantages that the metals in the waste ternary cathode material are effectively recycled and secondarily utilized, namely the three metals of cobalt, nickel and manganese in the waste ternary cathode material are subjected to resource treatment by a coupling method, so that the value-added utilization of the metals is realized, and the method has very important economic value and environmental protection significance.

Disclosure of Invention

In order to overcome the defects in the prior art, the invention provides a method for preparing a high-activity ternary metal oxide oxygen evolution catalyst by utilizing waste ternary nickel cobalt lithium manganate.

The technical scheme provided by the invention is as follows:

a method for preparing a high-activity ternary metal oxide oxygen evolution catalyst by utilizing waste ternary nickel cobalt lithium manganate sequentially comprises the following steps:

(1) crushing and sieving the waste ternary nickel cobalt lithium manganate positive electrode material, taking undersize, grinding the undersize into powder, soaking the powder in dilute hydrochloric acid, and taking supernatant A;

(2) adding sodium hydroxide solution into the solution A until the pH value of the solution is 7 to obtain B;

in the step, the pH value of the solution B needs to be controlled to be 7, namely the solution is neutral, the concentration of three metal ions in the solution is adjusted by sodium hydroxide, so that the concentration of nickel, cobalt and manganese ions in the solution adapts to the subsequent plasma discharge reaction process, the pH value at the position is closely related to the concentration of the three metal ions in the solution, the ion concentrations of the three metals influence the in-situ reaction of the subsequent plasma discharge process, each element has a competitive reaction in the plasma discharge reaction, meanwhile, the plasma discharge reaction also influences the distribution of each metal atom, even if the plasma discharge is ensured, each element is easy to capture, the discharge process cannot lead the in-situ reaction to be carried out too fast, the amount of the three metal elements contained in the catalyst material is related to the active site, the shape and the final catalytic performance of the catalyst, and each element exerts a synergistic effect to improve the catalytic performance of the catalyst, therefore, the ion content needs to be controlled within a certain range, and the pH of the solution is less than 7 or more than 7, so that the catalyst of the invention cannot be prepared;

(3) adding hexadecyl trimethyl ammonium bromide into the B to obtain C;

in the step, the hexadecyl trimethyl ammonium bromide is added for blending the reaction solution to enable the reaction solution to reach a uniform and stable state, so that the concentration of three metal ions in the subsequent plasma discharge reaction can reach the optimal reaction effect, and the phenomenon that the local concentration is too high to influence the reaction stability in the ion discharge process and further influence the catalytic stability of the prepared catalyst is avoided; on the other hand, the method can also prevent the reduction of the capture rate of three metal atoms in the ion discharge process caused by the non-uniform ions in the solution, so that the electrocatalyst prepared in the subsequent plasma discharge reaction process is a non-ternary electrocatalyst;

(4) placing foam copper with the diameter of 1cm multiplied by 1cm into the C, taking the foam copper as a working electrode and the C as a reaction solution, soaking the foam copper on the surface of the C solution, and simultaneously carrying out plasma discharge on the foam copper in an oxygen atmosphere to enable the surface of the foam copper to quickly and efficiently carry out chemical reaction;

in the step, a large amount of electron energy is generated by oxygen in the plasma discharging process, metal ions around the foam copper can be activated to react with the oxygen, and then Co-Ni-Mn ternary metal oxide with a regular shape is quickly formed;

(5) and (3) washing the self-supporting electrode for 3-6 times by using absolute ethyl alcohol and deionized water in sequence, and drying in vacuum to obtain the high-activity ternary metal oxide oxygen evolution catalyst.

As a limitation of the present invention:

in the step (1), the undersize is ground into powder with the particle size of 400 meshes.

In the step (1), the concentration of the dilute hydrochloric acid is 3-6M, and the soaking time is 10-15 h.

In the third step (3), the concentration of the hexadecyl trimethyl ammonium bromide is 8-16 g/L;

in the step, when the concentration of hexadecyl trimethyl ammonium bromide added into the solution B is less than 8g/L, the concentration of nickel, cobalt and manganese ions in the solution is uneven, and when plasma discharges, the effect of trapping metal atoms is poor, so that an electrocatalyst prepared in the subsequent plasma reaction process is a non-ternary metal oxygen evolution catalyst, the atom utilization rate of the reaction is reduced, and the catalytic activity of the electrocatalyst is influenced; when the concentration of the hexadecyl trimethyl ammonium bromide added into the solution B is more than 16g/L, the concentration of nickel, cobalt and manganese ions in the solution is locally too high, so that the ternary metal oxygen evolution catalyst prepared in the subsequent plasma reaction process is unstable, and the stability effect of electrocatalysis influenced;

in the step (4), the plasma discharge voltage is 150V, and the reaction time is 180-300 s;

in the step, the plasma discharge voltage and the discharge time have important influence on the appearance and the particle size of a final product, and when the discharge voltage is less than 150V, insufficient reaction of metal ions on the foam copper can occur, so that the self-supporting electrode has poor cohesiveness, the electrocatalyst is easy to fall off in the electrocatalysis process, and the catalysis effect is influenced; when the discharge voltage is more than 150V, more nano particles can be rapidly generated in the discharge process, and the nano particles are easy to agglomerate, so that the transmission of electrolyte ions and electrons among the nano particles is weakened, and the electro-catalysis performance is reduced;

when the plasma discharge time is less than 180s, the density of nano particles generated in the discharge process is low, so that the electro-catalysis performance of the nano particles is reduced; when the plasma discharge time is longer than 300s, more nano particles are generated in the discharge process, so that the transmission of electrolyte ions and electrons among the nano particles is weakened, and the electro-catalysis performance is reduced;

and (V) in the step (5), the drying temperature is 60-100 ℃, and the drying time is 6-12 h.

And (sixthly), in the step (4), the thickness of the copper foam is 0.01 cm.

The invention also has a limitation that the high-activity ternary metal oxide oxygen evolution catalyst is a three-dimensional network structure formed by the staggered nano-rods, and the diameter of each nano-rod is 100-200 nm;

as is well known, the morphology structure of the catalyst is closely related to the catalytic performance of the catalyst, in the application, the three-dimensional network structure formed by the staggered nanorods has the diameter of 100-200nm, and the structure lays a foundation for the large specific surface area and a large number of active sites of the nanorods, and meanwhile, the existence of hexadecyl trimethyl ammonium bromide in the reaction process of the invention and the in-situ reaction of oxygen in the plasma discharge process are important for preparing the catalyst with the morphology structure.

The above-described preparation process as a whole for preparing the catalyst of the invention is associated with the fact that the individual steps are not readily cleavable.

Compared with the prior art, the invention has the following advantages:

1. the method adopts the waste ternary nickel-cobalt-manganese cathode material as the raw material, obtains cobalt ions, nickel ions and manganese ions by a chemical dissolution method, has mild reaction conditions, realizes the maximum recovery of metal ions, and has low cost.

2. The hexadecyl trimethyl ammonium bromide is added in the preparation process to lay a foundation for the plasma reaction process, the waste ternary nickel-cobalt-manganese cathode material is recycled through the plasma in-situ reaction, the atom utilization rate of the reaction is high, the production process is simple, the process is controllable, and the method is suitable for large-scale industrial production.

3. Oxygen atoms are introduced in situ in the plasma discharge process, so that the prepared ternary metal oxide has more active sites, the oxygen evolution catalytic performance is greatly improved, and meanwhile, the catalyst has better catalytic activity and stability due to the synergistic catalysis of the ternary metal oxide in the catalytic process, and the catalytic performance of the catalyst is basically kept unchanged after 1000 cycles.

4. Realizes the recycling of waste, can realize large-scale production and realizes industrialization.

The method is suitable for recycling the ternary nickel cobalt lithium manganate cathode material in the waste lithium ion battery and further preparing the high-activity ternary metal oxide oxygen evolution catalyst.

Drawings

FIG. 1 is a TEM image of a sample prepared in example 1 of the present invention;

FIG. 2 is a graph of electrocatalytic LSV of a sample made in example 2 of the present invention;

FIG. 3 is a high-power TEM image of a sample prepared in example 3 of the present invention;

FIG. 4 is a graph of the electrocatalytic cycle stability of samples made in example 4 of the present invention;

FIG. 5 is an elemental analysis chart of a sample obtained in example 5 of the present invention;

FIG. 6 is a transmission electron microscope photograph of a sample obtained in example 6 of the present invention;

FIG. 7 is a graph comparing the current density at 300mV overpotential for samples prepared in examples 4, 5, and 6 of the present invention.

Detailed Description

The reagents used in the following examples are commercially available reagents unless otherwise specified, and the preparation methods and detection methods used therefor are well known in the art.

Example 1

A method for preparing a high-activity ternary metal oxide oxygen evolution catalyst by utilizing waste ternary nickel cobalt lithium manganate sequentially comprises the following steps:

(11) crushing and sieving a ternary nickel cobalt lithium manganate positive electrode material (containing nickel, cobalt and manganese) in the waste lithium ion battery, taking undersize, grinding the undersize into powder, sieving with a 400-mesh sieve, soaking in 3M dilute hydrochloric acid for 10 hours, and taking the supernatant as A;

(12) adding a certain amount of sodium hydroxide solution into the solution A until the pH value of the solution is 7 to obtain a solution B;

(13) adding 8g/L of hexadecyl trimethyl ammonium bromide into the B to obtain C;

(14) placing foam copper (the thickness is 0.01cm) with the diameter of 1cm multiplied by 1cm into the C, taking the foam copper as a working electrode and the C as a reaction solution, soaking the foam copper on the surface of the C solution, and simultaneously carrying out plasma discharge on the foam copper for 180s under the voltage of 150V in an oxygen atmosphere so as to enable the foam copper to quickly and efficiently generate chemical reaction on the surface of the foam copper;

(15) and (3) washing the self-supporting electrode for 3 times by using absolute ethyl alcohol and deionized water in sequence, and drying the self-supporting electrode for 6 hours in vacuum at the temperature of 60 ℃ to obtain the high-activity ternary metal oxide oxygen evolution catalyst.

The above prepared product was tested, and fig. 1 is a transmission electron microscope image of the sample prepared in example 1 of the present invention, from which it can be seen that the material is a three-dimensional network structure formed by a plurality of nanorods interlaced together, and the interlaced structure is favorable for the transmission of electrolyte ions and electrons.

Example 2

A method for preparing a high-activity ternary metal oxide oxygen evolution catalyst by utilizing waste ternary nickel cobalt lithium manganate sequentially comprises the following steps:

(21) crushing and sieving the waste ternary nickel cobalt lithium manganate positive electrode material, taking undersize, grinding the undersize into powder, sieving the powder with a 400-mesh sieve, soaking the powder in 4M dilute hydrochloric acid for 15 hours, and taking supernatant A;

(22) adding a certain amount of sodium hydroxide solution into the solution A until the pH value of the solution is 7 to obtain a solution B;

(23) adding 16g/L of hexadecyl trimethyl ammonium bromide into the B to obtain C;

(24) placing foam copper (the thickness is 0.01cm) with the diameter of 1cm multiplied by 1cm into the C, taking the foam copper as a working electrode and the C as a reaction solution, soaking the foam copper on the surface of the C solution, and simultaneously carrying out plasma discharge on the foam copper for 300s under the voltage of 150V in an oxygen atmosphere so as to enable the foam copper to quickly and efficiently generate chemical reaction on the surface of the foam copper;

(25) and (3) washing the self-supporting electrode for 6 times by using absolute ethyl alcohol and deionized water in sequence, and drying the self-supporting electrode for 12 hours in vacuum at the temperature of 100 ℃ to obtain the high-activity ternary metal oxide oxygen evolution catalyst.

FIG. 2 is a graph of the cycle stability test of the sample prepared in example 2 of the present invention, and the results show that the catalytic performance of the catalyst remains unchanged after the catalytic cycle lasts 10000s, and the catalyst has good cycle stability.

Example 3

A method for preparing a high-activity ternary metal oxide electrocatalyst by using waste ternary nickel cobalt lithium manganate sequentially comprises the following steps:

(31) crushing and sieving the waste ternary nickel cobalt lithium manganate positive electrode material, taking undersize, grinding the undersize into powder, sieving the powder with a 400-mesh sieve, soaking the powder in 6M dilute hydrochloric acid for 12 hours, and taking supernatant A;

(32) adding a certain amount of sodium hydroxide solution into the solution A until the pH value of the solution is 7 to obtain a solution B;

(33) adding 10g/L of hexadecyl trimethyl ammonium bromide into the B to obtain C;

(34) placing foam copper (the thickness is 0.01cm) with the diameter of 1cm multiplied by 1cm into the C, taking the foam copper as a working electrode and the C as a reaction solution, soaking the foam copper on the surface of the C solution, and simultaneously carrying out plasma discharge on the foam copper for 250s under the voltage of 150V in an oxygen atmosphere so as to enable the foam copper to quickly and efficiently generate chemical reaction on the surface of the foam copper;

(35) and (3) washing the self-supporting electrode for 5 times by using absolute ethyl alcohol and deionized water in sequence, and drying the self-supporting electrode for 10 hours in vacuum at the temperature of 80 ℃ to obtain the high-activity ternary metal oxide oxygen evolution catalyst.

FIG. 3 is a transmission electron microscope image of the sample prepared in example 3 of the present invention under high magnification, from which it can be seen that the sample is composed of many staggered nanorods with a diameter of 100-200 nm. The three-dimensional structure has large specific surface area and active sites, so that the electrocatalytic oxygen evolution activity is high and the catalytic performance is good. The obtained sample is also subjected to a cycle stability test (not shown), and the result shows that the catalytic performance of the catalyst is basically unchanged after the catalytic cycle is 10000s, and the catalyst has good cycle stability.

Example 4

A method for preparing a high-activity ternary metal oxide electrocatalyst by using waste ternary nickel cobalt lithium manganate sequentially comprises the following steps:

(41) crushing and sieving the waste ternary nickel cobalt lithium manganate positive electrode material, taking undersize, grinding the undersize into powder, sieving the powder with a 400-mesh sieve, and soaking the powder in 5M dilute hydrochloric acid for 13 hours; taking the supernatant as A;

(42) adding a certain amount of sodium hydroxide solution into the solution A until the pH value of the solution is 7 to obtain a solution B;

(43) adding 12g/L of hexadecyl trimethyl ammonium bromide into the B to obtain C;

(44) placing foam copper (the thickness is 0.01cm) with the diameter of 1cm multiplied by 1cm into the C, taking the foam copper as a working electrode and the C as a reaction solution, soaking the foam copper on the surface of the C solution, and simultaneously carrying out plasma discharge on the foam copper for 200s under the voltage of 150V in an oxygen atmosphere so as to enable the foam copper to quickly and efficiently generate chemical reaction on the surface of the foam copper;

(45) and (3) washing the self-supporting electrode for 5 times by using absolute ethyl alcohol and deionized water in sequence, and drying the self-supporting electrode for 8 hours in vacuum at 70 ℃ to obtain the high-activity ternary metal oxide oxygen evolution catalyst.

FIG. 4 is a chart of the cycle stability test of the sample prepared in example 4 of the present invention, and the results show that the catalytic performance of the catalyst is substantially unchanged after 1000 cycles of catalytic cycle, and the catalyst has good cycle stability.

Example 5 comparative example

This example is a method for preparing an oxygen evolution electrocatalyst using waste nickel cobalt lithium manganate, and is similar to the preparation steps of example 4, except that: plasma discharge is not adopted in the preparation process.

The specific steps are carried out in sequence as follows:

(51) crushing and sieving the waste ternary nickel cobalt lithium manganate positive electrode material, taking undersize, grinding the undersize into powder, sieving the powder with a 400-mesh sieve, soaking the powder in 5M dilute hydrochloric acid for 13 hours, and taking supernatant A;

(52) adding a certain amount of sodium hydroxide solution into the solution A until the pH value of the solution is 7 to obtain a solution B;

(53) respectively adding 12g/L of hexadecyl trimethyl ammonium bromide into the B to obtain C;

(54) placing foam copper (the thickness is 0.01cm) with the diameter of 1cm multiplied by 1cm into the solution C, taking the foam copper as a working electrode and the solution C as a reaction solution, and soaking the foam copper on the surface of the solution C to enable the surface of the solution C to generate chemical reaction;

(55) and (3) washing the self-supporting electrode for 5 times by using absolute ethyl alcohol and deionized water in sequence, and drying the self-supporting electrode for 8 hours in vacuum at 70 ℃ to obtain a sample.

Fig. 5 is an elemental analysis diagram of a sample prepared in example 5 of the present invention, from which it can be seen that the material is a single metal oxide of Cu, which proves that cobalt ions, nickel ions, and manganese ions in the waste ternary lithium nickel cobalt manganese oxide positive electrode material do not undergo chemical reaction in the absence of plasma voltage, so that the catalytic activity of the catalyst is very poor.

Example 6 comparative example

This example is a method for preparing an oxygen evolution catalyst using waste nickel cobalt lithium manganate, and is similar to the preparation steps of example 4, except that: cetyl trimethyl ammonium bromide is not added in the preparation process.

The specific steps are carried out in sequence as follows:

(61) crushing and sieving the waste ternary nickel cobalt lithium manganate positive electrode material, taking undersize, grinding the undersize into powder, sieving the powder with a 400-mesh sieve, soaking the powder in 5M dilute hydrochloric acid for 13 hours, and taking supernatant A;

(62) adding a certain amount of sodium hydroxide solution into the solution A until the pH value of the solution is 7 to obtain a solution B;

(63) placing foam copper (the thickness is 0.01cm) with the diameter of 1cm multiplied by 1cm into the B, taking the foam copper as a working electrode and the B as a reaction solution, soaking the foam copper on the surface of the solution B, and simultaneously carrying out plasma discharge on the foam copper for 200s under the voltage of 150V in the oxygen atmosphere to enable the foam copper to generate chemical reaction;

(64) and (3) washing the self-supporting electrode for 5 times by using absolute ethyl alcohol and deionized water in sequence, and drying the self-supporting electrode for 8 hours in vacuum at 70 ℃ to obtain the multi-element metal oxide oxygen evolution catalyst.

FIG. 6 is a TEM image of a sample prepared in example 6 of the present invention. As can be seen from the figure, cetyl trimethyl ammonium bromide is not added into the reaction solution, the nanorod catalysts synthesized in the plasma discharge reaction process are agglomerated together, the specific surface area is greatly reduced, and simultaneously, the nanorod catalysts are easy to fall off in the catalysis process, the catalysis stability is reduced, and the catalysis effect of the electrocatalyst is greatly reduced.

FIG. 7 is a graph comparing the current densities of samples prepared in example 4, example 5 and example 6 of the present invention. As can be seen, the catalytic activity of the oxygen evolution catalyst prepared in example 4 under the combined action of plasma discharge conditions and cetyltrimethylammonium bromide was 80 and 6 times higher than that of examples 5 and 6, respectively, at a voltage of 300 mV. The result shows that the method of plasma discharge reaction and the addition of cetyl trimethyl ammonium bromide play an important role in preparing the Co-Ni-Mn ternary metal oxygen evolution catalyst with high activity, in the preparation process, metal ions in the solution are uniformly distributed under the action of the cetyl trimethyl ammonium bromide, so that oxygen atoms can rapidly react with three ions of Co, Ni and Mn in the plasma discharge process, and then ternary metal oxide can be formed, the mutually crosslinked three-dimensional nanorod morphology is formed, and in the catalytic oxygen evolution process, the three metals of Co, Ni and Mn and oxygen are subjected to synergistic catalysis to form a composite active center beneficial to the electrocatalytic reaction, so that the synergistic catalytic effect is achieved.

Finally, it should be noted that: the above-mentioned embodiments are only used for illustrating the technical solution of the present invention, and not for limiting the same; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.