CN112299496B

CN112299496B - Method for regulating and controlling anion and cation defects on surface of spinel type metal oxide by dielectric barrier discharge

Info

Publication number: CN112299496B
Application number: CN202011277040.2A
Authority: CN
Inventors: 王召; 郑静轩; 侯宝红; 尹秋响; 龚俊波; 郝红勋
Original assignee: Tianjin University
Current assignee: Tianjin University
Priority date: 2020-11-16
Filing date: 2020-11-16
Publication date: 2022-01-18
Anticipated expiration: 2040-11-16
Also published as: CN112299496A

Abstract

The invention provides a method for regulating and controlling anion and cation defects on the surface of spinel type metal oxide by dielectric barrier discharge, which comprises the following steps: mixing reaction reagents and placing the mixture into a plasma reaction kettle; placing the reaction kettle between plasma generating electrodes; introducing plasma generation gas into the reaction kettle; adjusting the working voltage of the plasma generating device, generating the working voltage and the working current on the working electrode, puncturing the plasma generating gas, generating plasma, and acting on a reaction reagent; the resulting product was washed and dried. The concentration of the anion and cation defects on the surface of the spinel type metal oxide is regulated and controlled by adjusting at least one parameter of the kind of the reaction reagent, the kind of the plasma generation gas, the treatment power or the treatment time. The method has the beneficial effects that the surface of the spinel metal oxide can be directly modified, the defect of anions and cations with controllable target concentration is introduced, the electrochemical catalytic activity of the spinel is obviously improved, and the method is simple to operate, short in time, efficient and environment-friendly.

Description

Method for regulating and controlling anion and cation defects on surface of spinel type metal oxide by dielectric barrier discharge

Technical Field

The invention belongs to the technical field of electrochemical performance optimization of spinel type metal oxide, and particularly relates to a method for regulating and controlling anion and cation defects on the surface of spinel type metal oxide through dielectric barrier discharge and application of the method.

Background

Spinel type metal oxide (structural general formula: AB2O4) is considered to be an electrochemical catalyst with prospect because of the advantages of rich cation valence, adjustable metal composition, low cost, stable structure and the like. But the further popularization and application of the material are limited due to the defects of poor conductivity, slow kinetics and the like. Currently, scholars generally adopt a method of compounding with a carrier or regulating surface defects of the carrier to strengthen the electrochemical activity of the carrier.

At present, defect engineering receives extensive attention because the electronic structure on the surface of the spinel can be fundamentally adjusted, the energy band structure is optimized, and a target active site is exposed. For cationic and anionic defects in metal oxides, oxygen defects and metal defects are generally referred to, respectively. For example CN110534346A, CN111569859A and CN1316427A, introduce oxygen defects and metal defects on the metal oxide. However, the conventional methods often require high-temperature calcination, long-time hydrothermal treatment and the like, so that the temperature requirement is severe, the preparation process is complex, the energy consumption is high, the time is consumed, agglomeration is easily caused, and further large-scale industrial application is difficult.

CN111013560A discloses a method for introducing oxygen vacancies on the surface of titanium dioxide by using cold plasma, but the method needs to use hydrogen and the oxygen defect concentration is not controllable. At present, no patent report of introducing oxygen defects and metal defects on the surface of spinel by using cold plasma exists.

Disclosure of Invention

In order to overcome the defects in the prior art, the invention provides a method for regulating and controlling the anion and cation defects on the surface of spinel type metal oxide by dielectric barrier discharge, which comprises the following steps:

(1) mixing the reaction reagents and placing the mixture into a plasma reaction kettle;

(2) placing the reaction kettle between the plasma generating electrodes;

(3) introducing plasma generation gas into the reaction kettle;

(4) adjusting the working voltage of the plasma generating device, generating the working voltage and the working current on the working electrode, puncturing the plasma generating gas, generating plasma, and acting on a reaction reagent;

(5) washing and drying the obtained product;

wherein, the concentration of the anion defect and/or the cation defect on the surface of the spinel type metal oxide is regulated and controlled by adjusting at least one parameter of the kind of the reaction reagent, the kind of the plasma generating gas, the treatment power or the treatment time, and the reaction reagent comprises the spinel type metal oxide.

The spinel metal oxides of the present invention also include spinel metal oxide precursors that have not been subjected to high temperature processing.

And the processing power is the power acted by the working voltage and the working current generated on the working electrode in the step 4, and the processing power is adjusted by adjusting the working voltage and/or the working current. The processing power is the product of the working current and the working voltage, the processing power is increased, and the defects formed on the surface of the spinel type metal oxide are increased.

The processing time is the reaction time under the action of the working voltage and the working current generated on the working electrode in the step 4. The extended reaction time favors the formation of surface defects of the spinel metal oxide.

The dielectric barrier discharge method of the present invention is quite different from the conventional method. The dielectric barrier discharge plasma is a non-equilibrium plasma with a low bulk temperature and a high electron temperature. According to the method, high-energy electrons in plasma bombard metal or oxygen in spinel crystal lattices, so that the metal or oxygen escapes from the crystal lattices, oxygen defects or metal defects are formed on the surface, and charges are coated on the surfaces of particles, so that the particles are prevented from being agglomerated in the treatment process.

The spinel type metal oxide anion defect is an oxygen defect, and the spinel type metal oxide cation defect is a metal defect. Unless otherwise stated, the metal defects or cation defects of the present invention are spinel-type metal oxide metal defects or spinel-type metal oxide cation defects, and the oxygen defects or anion defects are spinel-type metal oxide oxygen defects or spinel-type metal oxide anion defects.

Any one of the above is preferably a spinel-type metal oxide composed of one or more metal elements selected from nickel, cobalt, aluminum, manganese and iron. It is further preferred that the metal elements in the spinel-type metal oxide include at least cobalt, and the cobalt forms a weaker chemical bond with oxygen, which is more favorable for forming metal defects under the action of plasma, thereby obtaining high catalytic activity. In another preferred embodiment of the present invention, the metal element in the spinel-type metal oxide includes at least one of iron or manganese, and the weak metal bond between iron or manganese and oxygen is favorable for obtaining the metal defect of the spinel metal oxide by the method provided by the present invention.

Preferably, the spinel-type metal oxide is in a powder or granular form, preferably a powder spinel-type metal oxide, having a larger reaction area.

Preferably, in any one of the above steps 1, the reaction reagent further comprises a basic compound. Experiments prove that by using the method provided by the invention, basic compounds are necessary to participate in generating the metal defects on the surface of the spinel metal oxide. This has not been reported in the prior art. The alkaline compound of the present invention is a substance which is soluble in water and can be ionized to generate hydroxide ions and has a pH of more than 7. The basic compound is preferably a strong base, which in the present invention means a basic compound capable of complete ionization, which has no ionization constant, or an infinite ionization constant. Further, the basic compound is preferably at least one of sodium hydroxide, lithium hydroxide, potassium hydroxide, ammonia water, rubidium hydroxide, calcium hydroxide, strontium hydroxide, barium hydroxide, radium hydroxide, aluminum hydroxide, magnesium hydroxide, and the like. The amount of the basic compound added is 1 to 100%, preferably 1%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100% of the molar number of the spinel-type metal oxide. The alkaline compound is solid or liquid, and sodium hydroxide, lithium hydroxide, potassium hydroxide, rubidium hydroxide, calcium hydroxide, strontium hydroxide, barium hydroxide, radium hydroxide, aluminum hydroxide and magnesium hydroxide are preferably solid. In a preferred embodiment of the present invention, sodium hydroxide and/or potassium hydroxide are used, and further experiments of specific examples prove that the sodium hydroxide and/or potassium hydroxide is beneficial to the formation of spinel-type metal oxide metal defects, and the concentration regulation of spinel-type metal oxide anion defects and/or cation defects is realized by adding the sodium hydroxide and/or potassium hydroxide.

In any of the above cases, in step 3, the plasma generating gas is one or more of argon, oxygen, air and nitrogen. The plasma generating gas is the atmosphere of the sample. The higher the oxygen content of the atmosphere in which the sample is placed, the more likely metal defects and the less likely oxygen defects will be generated. When the plasma generating gas is argon or nitrogen, oxygen defects are mainly generated; when the plasma generating gas is oxygen, metal defects are mainly generated; when the plasma generating gas is air, the defect of anion and cation mixed type is generated. The adjustment of the concentration of the spinel type metal oxide anion and cation defect is realized by adjusting the type of the plasma generating gas and the gas concentration. Accordingly, the present invention defines oxygen as a metal-deficient plasma generating gas, argon, nitrogen or a mixture thereof as an oxygen-deficient plasma generating gas, and air as a mixed type plasma generating gas. Preferably, the plasma generating gas is a combination of oxygen-deficient plasma generating gas and/or mixed plasma generating gas and metal-deficient plasma generating gas, by adjusting-oxygen-deficient plasma generating gas and/or mixed plasma generating gas: the concentration ratio of the metal-deficient plasma generated gas regulates and controls the concentration of spinel type metal oxide anion and/or cation defects in the reaction product. In the preferred embodiment, sodium hydroxide and potassium hydroxide are added to produce metal defects regardless of the atmosphere. Among them, metal defects contribute to OER reaction, and oxygen defects contribute to ORR. The detection method, the apparatus and the reagent for OER and ORR reactions adopted in the invention are all conventional methods and apparatus and reagents in the field, are described in published documents, and are not detailed herein. Wherein, OER (oxygen evolution reaction) is an oxygen evolution reaction and is used for evaluating the change of metal defects on the surface of spinel metal oxide in a reaction product; ORR (oxygen reduction reaction) is an oxygen reduction reaction, and the method is used for evaluating the change of oxygen defects on the surface of the spinel metal oxide in a reaction product. Specifically, the concentration of metal defects and/or oxygen defects on the surface of the spinel metal oxide in the reaction product is evaluated by comparing the current density at 1.2V (vs. Hg/HgO) at OER 1600r/min and the current density at 1.2V (vs. Hg/HgO) at ORR 1600r/min of the sample before and after the dielectric barrier discharge plasma treatment.

Any one of the above is preferable, in the step 4, the plasma is applied to the reactive agent for a time of 15s to 30 min.

Any one of the above preferable conditions is that in the step 4, the working voltage is 200-1000V, and the working current is 1-4A.

Any one of the above is preferable, in step 5, the washing is performed at least 6 times by using absolute ethanol and ultrapure water.

Any one of the above is preferable, in the step 5, the drying temperature is 60 ℃ and the drying time is 6 to 12 hours.

Any one of the above is preferably a plate type or a tube type reactor.

In any of the above cases, it is preferable that the operation temperature in step 4 is normal temperature and the operation pressure is normal pressure.

In any of the above cases, the drying is preferably performed by using a vacuum drying oven or an air drying oven.

The method provided by the invention overcomes the problems of long process period, complex equipment operation, strong reagent pollution and difficult introduction of metal defects in the prior art.

The invention has the following beneficial effects:

1. the method for regulating and controlling the anion and cation defects on the surface of the spinel metal oxide by using dielectric barrier discharge can directly modify the surface of the spinel metal oxide, introduce the anion and cation defects with target concentration, and remarkably improve the electrochemical catalytic activity of the spinel.

2. By adjusting the discharge gas and the processing power, the oxygen defect with controllable concentration can be obtained.

3. In the invention, metal defects can be introduced only by simply mixing the reaction reagents and carrying out plasma treatment for a short time.

4. In the invention, the metal defects with controllable concentration can be obtained by adjusting the reaction reagent and the treatment time.

5. In the invention, the whole process is carried out at room temperature by adopting the method for regulating and controlling the surface defects of the spinel metal oxide by dielectric barrier discharge, so that the agglomeration or the deterioration of the metal material can be effectively prevented.

6. The method can directly treat the spinel powder at room temperature and normal pressure, is environment-friendly, does not generate harmful substances, and is green and energy-saving.

Drawings

FIG. 1X-ray powder diffraction patterns of original spinel metal oxide and oxygen defect introduced by dielectric barrier discharge treatment under different gases in preferred embodiments 6, 7 and 8 of the present application.

FIG. 2 enlarged X-ray powder diffraction pattern of original spinel metal oxide and (311) crystal face after oxygen defect introduction by dielectric barrier discharge treatment under different gases in preferred embodiments 6, 7 and 8 of the present application.

FIG. 3 is a summary spectrum of X-ray photoelectron spectroscopy after introducing Co defects by treating the original spinel metal oxide with oxygen using dielectric barrier discharge in the preferred embodiment 7 of the present application.

FIG. 4 fine Co 2p spectrum of X-ray photoelectron spectroscopy after introducing Co defects by treating original spinel metal oxide with dielectric barrier discharge under oxygen in the preferred embodiment 7 of the present application.

FIG. 5 oxygen desorption curves of the original spinel metal oxide and the oxygen defect introduced by the dielectric barrier discharge treatment under different gases in the preferred embodiments 6, 7 and 8 of the present application.

FIG. 6 comparison of ORR performance of pristine spinel metal oxides in preferred examples 6, 7, 8 of the present application with oxygen defects introduced by treatment with dielectric barrier discharge in a blind atmosphere (1600 r/min).

FIG. 7 comparison of OER performance of pristine spinel metal oxides in the preferred embodiment 7 of the present application with metal defects introduced by treatment with dielectric barrier discharge in oxygen atmosphere (1600 r/min).

Detailed Description

The present invention will be more clearly and completely described in the following embodiments, but the described embodiments are only a part of the embodiments of the present invention, and not all of them. The examples are provided to aid understanding of the present invention and should not be construed to limit the scope of the present invention.

Example 1

Putting a nickel-cobalt spinel oxide sample in a plate-type plasma reaction kettle, introducing argon gas as discharge gas at normal temperature, turning on a power supply of a plasma generating device, adjusting the working voltage to be 100V and the working current to be 1.5A, carrying out power-on treatment for 30min at room temperature, analyzing the obtained product by XRD, XPS, O2-TPD and RDE, and proving that the nickel-cobalt spinel oxide sample rich in oxygen defects is obtained, the ORR performance is obviously improved, and the current density at 0.2V (vs. RHE) under 1600r/min is improved by 10.8%.

Example 2

Mixing nickel cobalt aluminum spinel oxide and sodium hydroxide, placing the mixture in a plate type plasma reaction kettle, introducing oxygen as discharge gas at normal temperature, turning on a power supply of a plasma generating device, adjusting the working voltage to be 100V and the working current to be 2A, and conducting electricity treatment for 6min at room temperature, wherein the obtained product is analyzed by XRD, XPS and RDE, so that a nickel cobalt spinel oxide sample rich in metal defects is obtained, the OER performance is obviously improved, and the current density at 1.2V (vs. Hg/HgO) at 1600r/min is improved by 2203.7%.

Example 3

Mixing nickel-cobalt spinel oxide and sodium hydroxide, placing the mixture in a plate type plasma reaction kettle, introducing oxygen as discharge gas at normal temperature, turning on a power supply of a plasma generating device, adjusting the working voltage to be 100V and the working current to be 2A, carrying out power-on treatment for 1min at room temperature, and analyzing the obtained product by XRD, XPS and RDE, wherein the metal defects and the oxygen defects of the obtained nickel-cobalt spinel oxide sample are improved to a certain extent, the ORR performance is improved, the ORR performance is obviously improved, the current density at 0.2V (vs. RHE) under 1600r/min is improved by 15.6%, the OER performance is also improved, and the current density at 1.2V (vs. Hg/HgO) under 1600r/min is improved by 100.6%.

Example 4

Mixing nickel cobalt aluminum spinel oxide and potassium hydroxide, placing the mixture in a plate type plasma reaction kettle, introducing air at normal temperature as discharge gas, turning on a power supply of a plasma generating device, adjusting the working voltage to be 100V and the working current to be 2A, and electrifying the mixture at room temperature for 3min, wherein the obtained product is analyzed by XRD, XPS and RDE, so that a nickel cobalt spinel oxide sample rich in metal defects is obtained, the OER performance is obviously improved, and the current density at 1.2V (vs. Hg/HgO) at 1600r/min is improved by 1501.3%.

Example 5

Putting a nickel-cobalt spinel oxide sample in a tubular plasma reaction kettle, introducing air as discharge gas at normal temperature, turning on a power supply of a plasma generating device, adjusting the working voltage to 200V and the working current to 1A, and electrifying at room temperature for 30min, wherein the obtained product is analyzed by XRD, XPS, O2-TPD and RDE, so that the nickel-cobalt spinel oxide sample rich in oxygen defects is obtained, the ORR performance is obviously improved, and the current density at 0.2V (vs. RHE) at 1600r/min is improved by 15.6%.

Example 6

Putting a nickel-cobalt spinel oxide sample in a tubular plasma reaction kettle, introducing argon gas as discharge gas at normal temperature, turning on a power supply of a plasma generating device, adjusting the working voltage to be 1000V and the working current to be 4A, electrifying for 3min at room temperature, washing the sample with ethanol for 7 times, drying at 60 ℃ for 12 hours, and analyzing the obtained product with XRD, XPS, O2-TPD and RDE to prove that the nickel-cobalt spinel oxide sample rich in oxygen defects is obtained, the ORR performance is obviously improved, and the current density at 0.2V (vs. RHE) at 1600r/min is improved by 100.8%. As shown in figure 1, the original spinel metal oxide and the X-ray powder diffraction spectrum after oxygen defects are introduced by processing under different gases by using dielectric barrier discharge, and the crystal structure of the spinel is not changed by introducing oxygen vacancies. As shown in fig. 2, the original spinel metal oxide and the (311) crystal plane after oxygen defect introduction are treated under different gases by dielectric barrier discharge to enlarge the X-ray powder diffraction spectrum, and the introduction of oxygen vacancy causes lattice expansion, thereby shifting the diffraction peak to a low angle. As shown in fig. 5, the oxygen desorption curve of the original spinel metal oxide and the oxygen-induced defect treated by the dielectric barrier discharge under different gases makes the spinel have stronger chemisorption performance to oxygen due to the oxygen-induced defect. As shown in fig. 6, the ORR performance of the pristine spinel metal oxide was compared (1600r/min) with oxygen defects introduced by treatment with dielectric barrier discharge under different atmospheres.

Compared with example 1, in example 6, the current density at 0.2V (vs. RHE) of the obtained oxygen defect-rich nickel-cobalt spinel oxide sample 1600r/min is improved remarkably by adjusting the working voltage and the reaction time and processing power.

Example 7

Mixing a nickel-cobalt spinel oxide sample with potassium hydroxide, placing the mixture in a tubular plasma reaction kettle, introducing oxygen as discharge gas at normal temperature, turning on a power supply of a plasma generating device, adjusting the working voltage to 1000V and the working current to 4A, performing electrification treatment for 6min at room temperature, washing the sample with ethanol for 7 times, drying the sample at 60 ℃ for 12 hours, and analyzing the obtained product by XRD, XPS, O2-TPD and RDE to prove that the nickel-cobalt spinel oxide sample rich in metal defects and a small amount of oxygen defects is obtained, the OER performance is obviously improved, and the current density at 1.2V (vs. Hg/HgO) at 1600r/min is improved by 2203.7%. As shown in figure 1, the original spinel metal oxide and the X-ray powder diffraction spectrum after oxygen defects are introduced by processing under different gases by using dielectric barrier discharge, and the crystal structure of the spinel is not changed by introducing oxygen vacancies. As shown in fig. 2, the original spinel metal oxide and the (311) crystal plane after oxygen defect introduction are treated under different gases by dielectric barrier discharge to enlarge the X-ray powder diffraction spectrum, and the introduction of oxygen vacancy causes lattice expansion, thereby shifting the diffraction peak to a low angle. As shown in fig. 5, the oxygen desorption curve of the original spinel metal oxide and the oxygen-induced defect treated by the dielectric barrier discharge under different gases makes the spinel have stronger chemisorption performance to oxygen due to the oxygen-induced defect. As shown in fig. 6, the ORR performance of the pristine spinel metal oxide was compared (1600r/min) with oxygen defects introduced by treatment with dielectric barrier discharge under different atmospheres. As shown in fig. 3, it is the general spectrum of X-ray photoelectron spectrum after introducing Co defects by treating original spinel metal oxide with dielectric barrier discharge under oxygen. As shown in fig. 4, the original spinel metal oxide and the X-ray photoelectron spectrum Co 2p fine spectrum obtained after Co defect is introduced by treatment under oxygen through dielectric barrier discharge lead to the increase of the corresponding metal valence due to the introduction of metal defect. As shown in fig. 7, the OER performance of the pristine spinel metal oxide was compared (1600r/min) with that of the metal defect introduced by treatment with a dielectric barrier discharge under an oxygen atmosphere.

Compared with the embodiment 6, the concentration of metal defects and oxygen defects in the product is adjusted by adjusting the reaction reagent and the plasma generation gas, and the current density is obviously improved.

Compared with embodiment 3, the OER performance is significantly improved by adjusting the operating voltage, current, processing time, and processing power.

Example 8

Putting a nickel-cobalt spinel oxide sample potassium hydroxide into a tubular plasma reaction kettle, introducing air as a discharge gas at normal temperature, turning on a power supply of a plasma generating device, adjusting the working voltage to 1000V and the working current to 4A, electrifying for 3min at room temperature, washing the sample for 7 times by using ethanol, drying for 12 hours at 60 ℃, analyzing the obtained product by XRD, XPS, O2-TPD and RDE, and proving that the obtained nickel-cobalt spinel oxide sample has certain improvement on metal defects and oxygen defects, the ORR performance is improved obviously, the current density at 0.2V (vs. RHE) at 1600r/min is improved by 15.6%, the OER performance is also improved, and the current density at 1.2V (vs. Hg/HgO) at 1600r/min is improved by 100.6%. As shown in fig. 2, the original spinel metal oxide and the (311) crystal plane after oxygen defect introduction are treated under different gases by dielectric barrier discharge to enlarge the X-ray powder diffraction spectrum, and the introduction of oxygen vacancy causes lattice expansion, thereby shifting the diffraction peak to a low angle. As shown in fig. 5, the oxygen desorption curve of the original spinel metal oxide and the oxygen-induced defect treated by the dielectric barrier discharge under different gases makes the spinel have stronger chemisorption performance to oxygen due to the oxygen-induced defect. As shown in fig. 6, the ORR performance of the pristine spinel metal oxide was compared (1600r/min) with oxygen defects introduced by treatment with dielectric barrier discharge under different atmospheres.

Compared with the embodiment 7, the concentration of metal defects and oxygen defects in the product is adjusted by adjusting the plasma generation gas, and the ORR and OER performance is improved. As shown in figure 1, the original spinel metal oxide and the X-ray powder diffraction spectrum after oxygen defects are introduced by processing under different gases by using dielectric barrier discharge, and the crystal structure of the spinel is not changed by introducing oxygen vacancies.

Example 9

Mixing a nickel-cobalt spinel oxide sample with potassium hydroxide, placing the mixture in a tubular plasma reaction kettle, introducing a mixed gas of argon and oxygen as a discharge gas at normal temperature, turning on a power supply of a plasma generation device, adjusting a working voltage to be 1000V and a working current to be 4A, carrying out electrification treatment for 3min at room temperature, washing the sample with ethanol for 7 times, drying the sample at 60 ℃ for 12 hours, and analyzing the obtained product with XRD, XPS, O2-TPD and RDE to prove that the metal defects and the oxygen defects of the obtained nickel-cobalt spinel oxide sample are improved to a certain extent, the ORR performance is improved, the ORR performance is obviously improved, the current density at 0.2V (vs. RHE) at 1600r/min is improved by 35%, the OER performance is also improved, and the current density at 1.2V (vs. Hg/HgO) at 1600r/min is improved by 500.6%.

Compared with the embodiment 7 or 8, the concentration of metal defects and oxygen defects in the product is adjusted by adjusting the plasma generation gas, and the ORR and OER performance is improved.

Example 10

Mixing a nickel-cobalt spinel oxide sample with potassium hydroxide, placing the mixture in a tubular plasma reaction kettle, introducing nitrogen as discharge gas at normal temperature, turning on a power supply of a plasma generating device, adjusting the working voltage to 1000V and the working current to 4A, performing electrification treatment for 3min at room temperature, washing the sample with ethanol for 7 times, drying the sample at 60 ℃ for 12 hours, and analyzing the obtained product by XRD, XPS, O2-TPD and RDE to prove that the nickel-cobalt spinel oxide sample rich in metal defects is obtained, the OER performance is obviously improved, and the current density at 1.2V (vs. Hg/HgO) at 1600r/min is improved by 1000.3%.

By adjusting the plasma generation gas, the concentrations of metal defects and oxygen defects in the product were adjusted and the OER performance was improved as compared with examples 7 to 9.

Example 11

Putting the manganese cobalt spinel oxide into a plate type plasma reaction kettle, introducing oxygen as discharge gas at normal temperature, turning on a power supply of a plasma generating device, adjusting the working voltage to be 200V and the working current to be 1A, electrifying for 30min at room temperature, washing a sample for 6 times by using water, drying for 6 hours at 60 ℃, analyzing the obtained product by XRD, XPS and RDE, wherein the metal defects of the manganese cobalt spinel oxide before and after treatment are not increased, and the electrochemical activity is not changed compared with that of the sample which is not treated by the plasma.

Example 12

The preparation method comprises the steps of mixing manganese cobalt spinel oxide with sodium hydroxide (or potassium hydroxide), placing the mixture in a plate type plasma reaction kettle, introducing oxygen as discharge gas at normal temperature, turning on a power supply of a plasma generation device, adjusting the working voltage to 200V and the working current to 1A, conducting electricity treatment for 30min at room temperature, washing a sample for 6 times with water, drying the sample for 6 hours at 60 ℃, and analyzing the obtained product by XRD, XPS and RDE to prove that a nickel cobalt spinel oxide sample rich in metal defects is obtained, the OER performance is obviously improved, and the current density at 1.2V (vs. Hg/HgO) at 1600r/min is improved by 1501.3%.

Compared with the embodiment 11, the types and the compositions of the reactants are further adjusted, and the concentration of the nickel-cobalt spinel oxide with metal defects is obviously improved and the OER performance is obviously improved by adding the sodium hydroxide. The invention shows that the sodium hydroxide and the potassium hydroxide have the function of regulating and controlling the anion and cation defects on the surface of the spinel metal oxide by using dielectric barrier discharge, help to realize the escape of metal atoms in the reaction process and improve the concentration of the metal defects in the product.

Example 13

Example 13 is the same as the specific operation method of examples 1 to 12, except that the strong base is lithium hydroxide, ammonia water, rubidium hydroxide, calcium hydroxide, strontium hydroxide, barium hydroxide, radium hydroxide, aluminum hydroxide, and magnesium hydroxide, and the results show that the current density at 1.2V (vs. hg/HgO) at OER 1600r/min is increased by mixing the strong base with one of nickel-cobalt spinel oxide, manganese-cobalt spinel oxide, aluminum-cobalt spinel oxide, nickel-iron spinel oxide, or hercynite oxide, and the OER performance of the obtained reaction product is significantly improved, which indicates that the surface metal defect concentration of the spinel metal oxide is improved.

Example 14

Example 14 the same procedure as in the previous examples was followed except that in the mixed reactant of nickel cobalt spinel metal oxide and sodium hydroxide or potassium hydroxide, the sodium hydroxide or potassium hydroxide was 1%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100% of the nickel cobalt spinel metal oxide. Experiments prove that the spinel metal oxide product obtained by the method according to the reaction mixture added according to the molar ratio has the advantages that the current density at 1.2V (vs. Hg/HgO) under OER 1600r/min is increased, the OER performance is obviously improved, and the concentration of metal defects on the surface of the spinel metal oxide is improved.

Example 15

Example 15 is the same as the above example except that nickel cobalt aluminate spinel oxide is mixed as a reactant with one of sodium hydroxide, lithium hydroxide, potassium hydroxide, rubidium hydroxide, calcium hydroxide, strontium hydroxide, barium hydroxide, radium hydroxide, aluminum hydroxide, magnesium hydroxide, respectively, wherein the preferred basic compound is 1%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100% of the spinel metal oxide. Experiments prove that the spinel metal oxide product obtained by the method according to the reaction mixture added according to the molar ratio has the advantages that the current density at 1.2V (vs. Hg/HgO) under OER 1600r/min is increased, the OER performance is obviously improved, and the concentration of metal defects on the surface of the spinel metal oxide is improved.

Example 16

Example 16 was conducted in the same manner as in the above examples except that the amount of ammonia added to the reactants of nickel cobalt spinel oxide or manganese cobalt spinel oxide, respectively, was 1%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100% of the spinel metal oxide. Experiments prove that the spinel metal oxide product obtained by the method according to the reaction mixture added according to the molar ratio has the advantages that the current density at 1.2V (vs. Hg/HgO) under OER 1600r/min is increased, the OER performance is obviously improved, and the concentration of metal defects on the surface of the spinel metal oxide is improved.

Claims

1. A method for regulating and controlling anion and cation defects on the surface of spinel type metal oxide by dielectric barrier discharge comprises the following steps:

(2) placing the reaction kettle between the plasma generating electrodes;

(3) introducing plasma generation gas into the reaction kettle;

(5) washing and drying the obtained product;

the method is characterized in that the concentration of anion defects and/or cation defects on the surface of the spinel-type metal oxide is regulated and controlled by adjusting at least one parameter of the type of a reaction reagent, the type and composition of plasma generation gas, treatment power and treatment time, wherein the reaction reagent comprises the spinel-type metal oxide and a basic compound, and the basic compound is a substance which is dissolved in water, can ionize hydroxide ions and has a pH value of more than 7.

2. The method of claim 1, wherein: in step 1, the spinel type metal oxide is a spinel type metal oxide composed of one or more metal elements of nickel, cobalt, aluminum, manganese and iron.

3. The method of claim 1, wherein: in the step 3, the plasma generating gas is one or more of argon, oxygen, air and nitrogen.

4. The method of claim 1, wherein: in the step 4, the time of the plasma acting on the reaction reagent is 15s-30 min.

5. The method of claim 1, wherein: in the step 4, the working voltage is 200-1000V, and the working current is 1-4A.

6. The method of claim 1, wherein: in the step 5, the washing is carried out for at least 6 times by adopting absolute ethyl alcohol and ultrapure water.

7. The method of claim 1, wherein: in the step 5, the drying temperature is 60 ℃, and the drying time is 6-12 hours.

8. The method according to any one of claims 1 to 7, wherein: the plasma reaction kettle adopts a plate type or tubular type reaction kettle.

9. The method of claim 1, wherein: in the step 4, the operation temperature is normal temperature, and the operation pressure is normal pressure.