CN116200773A - Transition metal electrocatalyst rich in twin crystal structure, and preparation method and application thereof - Google Patents

Transition metal electrocatalyst rich in twin crystal structure, and preparation method and application thereof Download PDF

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CN116200773A
CN116200773A CN202310209877.0A CN202310209877A CN116200773A CN 116200773 A CN116200773 A CN 116200773A CN 202310209877 A CN202310209877 A CN 202310209877A CN 116200773 A CN116200773 A CN 116200773A
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electrocatalyst
transition metal
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韩朝
李维杰
刘咏
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Central South University
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    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
    • C25B11/04—Electrodes; Manufacture thereof not otherwise provided for characterised by the material
    • C25B11/051—Electrodes formed of electrocatalysts on a substrate or carrier
    • C25B11/073—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material
    • C25B11/091—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material consisting of at least one catalytic element and at least one catalytic compound; consisting of two or more catalytic elements or catalytic compounds
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B1/00—Electrolytic production of inorganic compounds or non-metals
    • C25B1/01—Products
    • C25B1/02—Hydrogen or oxygen
    • C25B1/04—Hydrogen or oxygen by electrolysis of water
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
    • C25B11/04—Electrodes; Manufacture thereof not otherwise provided for characterised by the material
    • C25B11/051—Electrodes formed of electrocatalysts on a substrate or carrier
    • C25B11/055—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the substrate or carrier material
    • C25B11/057—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the substrate or carrier material consisting of a single element or compound
    • C25B11/065—Carbon

Abstract

The invention belongs to the technical field of electrocatalysts, and discloses a preparation method of a transition metal electrocatalyst rich in a twin crystal structure, which comprises the following steps: dissolving water-soluble transition metal salt with a certain component ratio and a certain amount of sodium citrate and polyvinylpyrrolidone in water to form a solution A; dissolving Prussian blue analogues in water to form a solution B; adding the solution B into the solution A under the stirring condition, continuously stirring for a certain time to react, cleaning and drying the precipitate obtained by the reaction, and carbonizing under the protection of inert atmosphere; and (3) pickling the carbonized sample with an acid solution, and centrifuging, cleaning and drying to obtain the transition metal electrocatalyst rich in the twin crystal structure. The electrocatalyst synthesized by the preparation method is a composite of metal and carbonaceous material, has excellent catalytic performance on different reactions such as OER, ORR, HER in alkaline environment, and has good stability.

Description

Transition metal electrocatalyst rich in twin crystal structure, and preparation method and application thereof
Technical Field
The invention relates to the technical field of electrocatalysts, in particular to a transition metal electrocatalyst rich in a twin crystal structure, and a preparation method and application thereof.
Background
Since fossil fuels cause environmental problems (e.g., greenhouse effect) during use, technologies related to the acquisition and utilization of clean energy have been widely paid attention and studied worldwide. Typical examples are metal-air batteries, hydrogen-oxygen fuel cells, water electrolysis hydrogen production technology, and the like. The essence of these techniques is the conversion of electrical and chemical energy by redox reactions utilizing multiple electron transfer, for example, the charge and discharge reactions of large-scale energy-storage metal-air batteries are Oxygen Evolution (OER) and reduction (ORR), respectively; the essence of the fuel cell reaction is the use of oxidation of Hydrogen (HOR) and reduction of Oxygen (ORR) to generate electrical energy; the positive electrode and the negative electrode for preparing hydrogen by electrolyzing water as green high-energy fuel respectively have oxygen precipitation (OER) and hydrogen precipitation (HER) reactions under the action of external voltage. Therefore, the use of the electrocatalyst has an important promoting effect on the oxidation-reduction reaction of the multi-electron transfer, can effectively reduce the overvoltage generated by the reaction, and improves the energy conversion efficiency of the corresponding clean energy device.
However, a common problem faced by the clean energy techniques listed above is the lack of inexpensive, efficient and stable electrocatalysts. For example, the most efficient hydrogen evolution reaction electrocatalyst in the water electrolysis hydrogen production technology is expensive platinum metal, costly and easily poisoned by methanol and CO; the most effective electrocatalysts for OER and ORR reactions are the expensive noble metals Ir/Ru and Pt.
The transition metal-based electrocatalyst has a catalytic performance which is not much different from that of noble metal and has better stability due to the adjustable 3d orbit, so the transition metal-based electrocatalyst becomes an important direction for developing the electrocatalyst. In particular, the multifunctional transition metal-based electrocatalyst may exhibit high electrocatalytic activity for a variety of different redox reactions, such as OER/ORR/HER, etc. Therefore, the catalyst cost can be further reduced, and the popularization and promotion of the clean energy technology are facilitated. There is still a lack of a low cost method for preparing multifunctional transition metal-based electrocatalysts. And the performance of the multifunctional electrocatalyst prepared at present is still far from that of the corresponding noble metal-based electrocatalyst.
For example, CN113388847B discloses a metal sulfide/nitrogen doped carbon electrocatalyst, which is essentially formed by carbonizing a prussian blue homolog, etching with ammonia water and performing weather vulcanization to form a heterostructure, and has stable product activity, but the preparation process is complex, waste water and waste gas pollution are easy to generate, and the product has good catalytic activity only for alkaline medium HER and OER. The electrocatalyst component synthesized by the preparation method is a metal/nitrogen doped carbon electrocatalyst compound, contains rich nano twin crystal structures, is simple and easy to implement in preparation process, has almost no emission, can have excellent catalytic performance on different reactions such as OER, ORR, HER in alkaline environment, and has good stability.
It should be noted that the foregoing description of the background art is only for the purpose of facilitating a clear and complete description of the technical solutions of the present application and for the convenience of understanding by those skilled in the art. The above-described solutions are not considered to be known to the person skilled in the art simply because they are set forth in the background section of the present application.
Disclosure of Invention
In view of the above-mentioned shortcomings existing at present, the present invention provides a transition group metal electrocatalyst rich in twin structures, a preparation method and application thereof, and the present invention provides a transition group metal-based composite electrocatalyst which incorporates dispersed mono/diatomic structures, alloy particles, and most importantly twin structures simultaneously by controlling carbonization in combination with in-situ crystal form transformation. The electrocatalyst synthesized by the preparation method is a composite of metal and carbonaceous material, has excellent catalytic performance on different reactions such as OER, ORR, HER in alkaline environment, and has good stability.
In order to achieve the above object, the present invention provides a method for preparing a transition metal electrocatalyst rich in a twin structure, comprising the steps of:
step 1: dissolving water-soluble transition metal salt with a certain component ratio and a certain amount of sodium citrate and polyvinylpyrrolidone in water to form a solution A; dissolving Prussian blue analogues in water to form a solution B;
step 2: adding the solution B into the solution A under the stirring condition, continuously stirring for a certain time to react, cleaning and drying the precipitate obtained by the reaction, and carbonizing under the protection of inert atmosphere;
step 3: and (3) pickling the carbonized sample with an acid solution, and centrifuging, cleaning and drying to obtain the transition metal electrocatalyst rich in the twin crystal structure.
According to one aspect of the present invention, in step 1, the transition group metal includes two or more metals of Fe, co, and Ni, and the water-soluble transition group metal salt includes any one or more of sulfate, acetate, chloride, and nitrate corresponding to the transition group metal.
According to one aspect of the present invention, the water-soluble transition group metal salt includes a cobalt salt and a nickel salt, and the water-soluble transition group metal salt and the Prussian blue analog as a whole, wherein the ratio of the amounts of substances of cobalt element to nickel element is 7:2.
According to one aspect of the invention, the ratio of the sodium citrate to the amount of total metal ion species in the water-soluble transition metal salt is 0.1-1:1-5; the ratio of the mass of the polyvinylpyrrolidone to the amount of the substance of the total metal ions in the water-soluble transition metal salt is 0.1 to 1:1 to 5 (g/mmol).
According to one aspect of the present invention, in step 1, the prussian blue analog includes K 3 Co(CN) 6 、Na 3 Co(CN) 6 、K 3 Fe(CN) 6 、Na 3 Fe(CN) 6 One or more of the following.
According to one aspect of the invention, in the step 2, the stirring is continued for a certain time to perform the reaction for 1-12 hours; the inert atmosphere is Ar or N 2 The method comprises the steps of carrying out a first treatment on the surface of the The carbonization treatment is specifically to heat up to 500-900 ℃ at a speed of 1-10 ℃/min and preserve heat for 0.5-5 hours.
In accordance with one aspect of the invention, in step 3, H in the acidic solution + The concentration of the ions is 0.1 to 7mol/L.
According to one aspect of the invention, in step 3, the temperature of the acid washing is from room temperature to 100 ℃, and the time of the acid washing is from 0.5 to 72 hours.
Based on the same inventive concept, the invention also provides the transition group metal electrocatalyst rich in twin crystal structure prepared by any one of the preparation methods, wherein the electrocatalyst utilizes carbon cladding and in-situ phase structure transformation to induce a large number of in-crystal twin crystal structures when alloy particles of different components of the transition group metal are carbonized at a certain temperature, and combines nitrogen doped carbon, metal atom doped carbon and alloy particles to form a multistage multi-site catalytic system.
Based on the same inventive concept, the invention also discloses an application of the transition group metal electrocatalyst rich in the twin structure or the transition group metal electrocatalyst rich in the twin structure prepared by any one of the preparation methods, wherein the application of the electrocatalyst is specifically as follows: accelerating the precipitation of oxygen, the reduction of oxygen and the precipitation of hydrogen in alkaline environments.
The mechanism of the invention: the invention takes a Prussian blue analogue of transition group metal as a template, and prepares the transition group metal-carbon composite through a one-step carbonization method. Due to the porous metal-organic framework structure of the Prussian blue analogues, a porous carbon matrix containing a metal-N-C structure can be formed after controlled carbonization; the transition group metals are also converged into metal or alloy nano particles through component design; and the metal/alloy nano particles can be changed from a high-temperature phase to a low-temperature phase after carbonization under proper components and conditions, and the intragranular twin crystals are extremely easy to induce in the phase transition process, so that the catalytic performance can be further modulated; bare metal/alloy particles are washed away by acid washing, eventually leaving behind a carbon-coated metal/alloy nanoparticle structure. The composite electrocatalyst rich in the twin crystal structure has good conductivity and multifunctional catalytic activity, effectively reduces the overpotential of OER, ORR and HER in alkaline environment, and shows excellent long-term stability. The method has important theoretical and practical significance for developing non-noble metal-based multifunctional electrocatalyst and energy conversion and storage devices.
The invention has the beneficial effects that:
the structural morphology of the invention is carbon@alloy containing Co/Ni/N dopingParticles, a composite structure. The invention utilizes the carbon cladding and in-situ phase structure transformation (such as Co) to simultaneously occur when the alloy particles with different components of transition group metals are carbonized at a certain temperature 7 Ni 2 Fcc-hcp phase transformation, which occurs when alloy nanoparticles are carbonized and cooled at 600 ℃, induces the generation of a large number of intragranular twinning structures, combining nitrogen-doped carbon, metal atom-doped carbon, and alloy particles, forming a unique multi-stage multi-site catalytic system. Finally, the multistage composite structure is endowed with high catalytic activity for various reactions (such as OER, ORR, HER and the like) in an alkaline environment, and meanwhile, the multistage composite structure has good stability.
Drawings
FIG. 1 (a) is a morphology of the electrocatalyst according to example 1 of the invention at low transmission comprising nanoparticles and hollow carbon spheres; FIG. 1 (b) is a topography of the hollow carbon sphere of FIG. 1 (a) at high magnification transmission; FIG. 1 (c) is a topography of the hollow carbon sphere of FIG. 1 (a) under high magnification dark field image transmission, with bright spots representing metal atoms doped into the carbon matrix; FIG. 1 (d) is Co of FIG. 1 (a) 7 Ni 2 Topography of the nanoparticle under high magnification transmission; fig. 1 (e) is an IFFT photograph of the square frame region in fig. 1 (d), which clearly shows the twin structure;
FIG. 2 (a) is a topography of the electrocatalyst according to comparative example 1 of the invention at low transmission comprising nanoparticles and hollow carbon spheres; FIG. 2 (b) is a graph of the morphology of the electrocatalyst of FIG. 2 (a) at high transmission, with hollow carbon structures and nanoparticles coexisting; FIG. 2 (c) is a topography of the hollow carbon sphere of FIG. 2 (a) under high magnification dark field image transmission, with bright spots representing metal atoms doped into the carbon matrix; FIG. 2 (d) is Co of FIG. 2 (a) 5 Ni 4 The morphology of the nanoparticle under high-magnification transmission is uniform in structure as pure fcc phase, without lattice distortion and twin structure similar to that of fig. 1 (d);
FIG. 3 (a) is a graph showing the transmission profile of the electrocatalyst hollow carbon structure according to comparative example 2 in high magnification dark field images, wherein the bright spots represent metal atoms doped into the carbon matrix; FIG. 3 (b) is Co of FIG. 3 (a) 6 Ni 3 The shape graph of the nano particles under high resolution transmission has uniform structure of pure fcc phase and no lattice torsionA twinned structure similar to that of fig. 1 (d); FIG. 3 (c) is a graph showing the transmission morphology of the electrocatalyst hollow carbon structure according to comparative example 3 in a high magnification dark field image, where the bright spots represent metal atoms doped into the carbon matrix; FIG. 3 (d) is a topography of the Co-Co nanoparticles of FIG. 3 (c) at high resolution transmission, with a structure that is homogeneous to a pure hcp phase, without lattice distortion and twin structure similar to that of FIG. 1 (d); FIG. 3 (e) is a graph showing the transmission morphology of the electrocatalyst hollow carbon structure according to comparative example 4 in a high magnification dark field image, where the bright spots represent metal atoms doped into the carbon matrix; FIG. 3 (f) is Co of FIG. 3 (e) 3 Ni 6 The morphology of the nanoparticle under high resolution transmission is uniform in structure as pure fcc phase, without lattice distortion and twin structure similar to that of fig. 1 (d);
FIG. 4 (a) is an LSV curve of OER reaction of the electrocatalysts of example 1, comparative examples 1-4 in 1M KOH solution at 1600 revolutions of the rotating disc; FIG. 4 (b) is an LSV plot of HER reactions in 1M KOH solution for the electrocatalysts of example 1, comparative examples 1-4 at 1600 revolutions of the rotating disk; FIG. 4 (c) is an LSV plot of the ORR reaction of the electrocatalysts of example 1, comparative examples 1-4 in 0.1M KOH solution at 1600 rpm of the rotating disc;
FIG. 5 (a) is a schematic view of a zinc-air cell device for electrocatalyst preparation test according to example 1 of the invention; FIG. 5 (b) is a graph showing the discharge voltage-discharge current density and the battery output power density of the electrocatalyst according to example 1 of the invention; FIG. 5 (c) is a graph of the cell cycle of the electrocatalyst according to example 1 of the invention, wherein the blue arrow represents the addition of electrolyte;
FIG. 6 is a graph showing the stability of the electrolytic water cracking test of the electrocatalyst of example 1 of the invention as a positive and negative electrocatalyst, and the internal panels are photographs of the corresponding devices;
FIG. 7 (a) is a graph showing the stability test of the electrocatalyst according to example 1 of the invention at various voltages; FIG. 7 (b) is a high resolution transmission plot of the electrocatalyst according to example 1 of the invention after OER stabilization test, the white arrow identifies the still-present twinning structure; fig. 7 (c) is a high resolution transmission plot of the electrocatalyst according to example 1 of the invention after HER stabilization testing, white arrows identifying the still existing twinning structure; fig. 7 (d) is a high resolution transmission plot of the electrocatalyst according to example 1 of the invention after ORR stabilization test, white arrows identifying the still existing twinning structure.
Detailed Description
In order that the invention may be more readily understood, the invention will be further described with reference to the following examples. It should be understood that these examples are intended to illustrate the invention and not to limit the scope of the invention, and that the described embodiments are merely some, but not all, of the embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention. Unless defined otherwise, the terms of art used hereinafter are consistent with the meanings understood by those skilled in the art; unless otherwise indicated, all the materials and reagents referred to herein are commercially available or may be prepared by well-known methods.
A common problem faced by clean energy technology is the lack of inexpensive, efficient and stable electrocatalysts.
In order to solve the problems, the invention provides a preparation method of a transition metal electrocatalyst rich in a twin crystal structure, which comprises the following steps:
step 1: dissolving water-soluble transition metal salt with a certain component ratio and a certain amount of sodium citrate and polyvinylpyrrolidone in water to form a solution A; dissolving Prussian blue analogues in water to form a solution B;
preferably, in step 1, the transition group metal includes two or more metals of Fe, co, and Ni, and the water-soluble transition group metal salt includes any one or more of sulfate, acetate, chloride, and nitrate corresponding to the transition group metal. Preferably, the water-soluble transition metal salt includes a cobalt salt and a nickel salt, and the water-soluble transition metal salt and the Prussian blue analog as a whole have a mass ratio of cobalt element to nickel element of 7:2. Preferably, the sodium citrate is mixed with the water-soluble transition metal saltThe ratio of the total metal ion substances is 0.1-1:1-5; more preferably, the ratio of the sodium citrate to the amount of total metal ion species in the water-soluble transition metal salt is 1:1; the ratio of the mass of the polyvinylpyrrolidone to the mass of the total metal ion in the water-soluble transition metal salt is 0.1-1:1-5 (g/mmol); more preferably, the ratio of the mass of the polyvinylpyrrolidone to the amount of the substance of the total metal ions in the water-soluble transition metal salt is 1:6 (g/mmol). Preferably, in step 1, the prussian blue analog includes K 3 Co(CN) 6 、Na 3 Co(CN) 6 、K 3 Fe(CN) 6 、Na 3 Fe(CN) 6 One or more of the following.
Step 2: adding the solution B into the solution A under the stirring condition, continuously stirring for a certain time to react, cleaning and drying the precipitate obtained by the reaction, and carbonizing under the protection of inert atmosphere;
preferably, in the step 2, the continuous stirring is carried out for a certain time for 1-12 hours; the inert atmosphere is Ar or N 2 The method comprises the steps of carrying out a first treatment on the surface of the The carbonization treatment is specifically to heat up to 500-900 ℃ at a speed of 1-10 ℃/min and preserve heat for 0.5-5 hours; more preferably, the reaction is carried out for 12 hours after the stirring is continued for a certain time; the inert atmosphere is N 2 The method comprises the steps of carrying out a first treatment on the surface of the The carbonization treatment is specifically to heat up to 600 ℃ at a speed of 5 ℃/min and preserve heat for 1 hour. Preferably, the carbonization treatment is specifically performed in a tube furnace.
Step 3: and (3) pickling the carbonized sample with an acid solution, and centrifuging, cleaning and drying to obtain the transition metal electrocatalyst rich in the twin crystal structure.
Preferably, in step 3, H in the acidic solution + The concentration of the ions is 0.1 to 7mol/L; more preferably, H in the acidic solution + The concentration of the ions is 0.5 to 4mol/L. Preferably, in step 3, the temperature of the acid washing is room temperature to 100 ℃, the time of the acid washing is 0.5 to 72 hours, and the acid solution is preferably hydrochloric acid; more preferably, the temperature of the acid washing is 80 ℃ at room temperatureThe pickling time is 24 hours.
Further details are provided below in connection with specific examples.
Example 1
A preparation method of a transition metal electrocatalyst rich in a twin crystal structure comprises the following steps:
taking 4mmol CoSO 4 ·7H 2 O,2mmol Ni(CH 3 COO) 2 ·4H 2 O,1g polyvinylpyrrolidone (PVP) and 6mmol sodium citrate dihydrate (Na 3 C 6 H 5 O 7 ·2H 2 O) dissolving in 40ml deionized water to form a solution A;3mmol K 3 Co(CN) 6 Likewise dissolved in 40ml deionized water to form solution B. Solution B was slowly added to solution A with stirring at room temperature and stirring was continued for 12 hours, and the resulting precipitate was washed and dried at N 2 Heating to 600 ℃ at a speed of 5 ℃/min under the protection of atmosphere, and preserving heat for 1 hour. Finally, the carbonized sample was stirred in 4M HCl solution at 80℃for 24 hours. And finally, cleaning and drying to obtain a final product. Wherein the total content ratio of Co to Ni is 7 (4 mmol CoSO) 4 +3mmol K 3 Co(CN) 6 ):2. The morphology structure is shown in figure 1.
Comparative example 1
Based on example 1, coSO was used 4 ·7H 2 O and Ni (CH) 3 COO) 2 ·4H 2 O was changed to 2mmol and 4mmol, respectively, and the other preparation methods were exactly the same as in example 1, to obtain comparative example 1. Wherein the total content ratio of Co to Ni is 5 (2 mmol CoSO) 4 +3mmol K 3 Co(CN) 6 ):4. The morphology structure is shown in figure 2.
Comparative example 2
Based on example 1, coSO was used 4 ·7H 2 O and Ni (CH) 3 COO) 2 ·4H 2 O was changed to 3mmol and 3mmol, respectively, and the other preparation methods were exactly the same as in example 1, to obtain comparative example 2. Wherein the total content ratio of Co to Ni is 6 (3 mmol CoSO) 4 +3mmol K 3 Co(CN) 6 ):3. The morphology is shown in fig. 3 (a-b).
Comparative example 3
In the base of example 1On, coSO 4 ·7H 2 O and Ni (CH) 3 COO) 2 ·4H 2 O was changed to 6mmol and 0mmol, respectively, and the other preparation methods were exactly the same as in example 1, to obtain comparative example 3. Wherein the total content ratio of Co to Ni is 9 (6 mmol CoSO) 4 +3mmol K 3 Co(CN) 6 ):0. The morphology is shown in FIG. 3 (c-d).
Comparative example 4
Based on example 1, coSO was used 4 ·7H 2 O and Ni (CH) 3 COO) 2 ·4H 2 O was changed to 0mmol and 6mmol, respectively, and the other preparation methods were exactly the same as in example 1, to obtain comparative example 4. Wherein the total content ratio of Co to Ni is 3 (0 mmol CoSO) 4 +3mmol K 3 Co(CN) 6 ):6. The morphology is shown in FIG. 3 (e-f).
Performance detection and result analysis:
the final products prepared in example 1 and comparative examples 1-4 were ultrasonically mixed with propanol/ethanol/water and Nafion solution and then applied to a glassy carbon electrode by dropping, and then subjected to linear sweep voltammetry test in 0.1-1.0M KOH electrolyte to obtain LSV curves as shown in fig. 4 and electrocatalytic properties as shown in table 1, and as can be seen in fig. 1 and table 1, it can be seen that example 1 significantly reduced oxygen evolution, hydrogen evolution and oxygen reduction overpotential, and exhibits optimal multifunctional catalytic characteristics.
Table 1:
Figure BDA0004112250500000081
in table 1:
a. means that the current density of OER reaction reaches 10mA.cm -2 Overvoltage at the time; the smaller the OER performance is, the better;
b. means that the electrode current density at which HER reaction occurs reaches 10mA.cm -2 Overvoltage at the time; smaller indicates better HER performance;
c.E 1/2 refers to the voltage at which the ORR reaches 1/2 of the saturation current; the higher indicates a smaller ORR overpotential.
As can be seen from fig. 1, 2 and 3, the electrocatalyst structure of the invention contains both the diatomic structure, the alloy particles, and most importantly the twinning structure. As can be seen from fig. 4, the electrocatalyst of the invention has high catalytic activity for Oxygen Evolution (OER), 4-electron oxygen reduction (ORR) and Hydrogen Evolution Reaction (HER) in alkaline environment under the combined action of three possible active sites. As can be seen from fig. 5 to 7, the electrocatalyst of example 1, which is the only catalyst for the actual electrochemical device, has higher catalytic performance and better stability, and improves the energy efficiency of the device.
The foregoing is merely illustrative of the present invention, and the present invention is not limited thereto, and any changes or substitutions easily contemplated by those skilled in the art within the technical scope of the present invention should be included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims (10)

1. A method for preparing a transition metal electrocatalyst rich in twin structures, comprising the steps of:
step 1: dissolving water-soluble transition metal salt with a certain component ratio and a certain amount of sodium citrate and polyvinylpyrrolidone in water to form a solution A; dissolving Prussian blue analogues in water to form a solution B;
step 2: adding the solution B into the solution A under the stirring condition, continuously stirring for a certain time to react, cleaning and drying the precipitate obtained by the reaction, and carbonizing under the protection of inert atmosphere;
step 3: and (3) pickling the carbonized sample with an acid solution, and centrifuging, cleaning and drying to obtain the transition metal electrocatalyst rich in the twin crystal structure.
2. The method for preparing a transition group metal electrocatalyst rich in twin structures according to claim 1, wherein in step 1, the transition group metal comprises two or more metals selected from Fe, co, and Ni, and the water-soluble transition group metal salt comprises any one or more of sulfate, acetate, chloride, and nitrate corresponding to the transition group metal.
3. The method for producing a transition group metal electrocatalyst rich in twin structures according to claim 2, wherein the water-soluble transition group metal salt comprises a cobalt salt and a nickel salt, the water-soluble transition group metal salt and the prussian blue analogue as a whole, wherein the ratio of the amounts of substances of cobalt element and nickel element is 7:2.
4. The method for preparing a transition metal electrocatalyst rich in twin structures according to claim 1, wherein the ratio of the amount of sodium citrate to the total metal ion species in the water-soluble transition metal salt is 0.1 to 1:1 to 5; the ratio of the mass of the polyvinylpyrrolidone to the amount of the substance of the total metal ions in the water-soluble transition metal salt is 0.1 to 1:1 to 5 (g/mmol).
5. The method for preparing a transition metal electrocatalyst rich in twin structure according to claim 1, wherein in step 1, the prussian blue analog comprises K 3 Co(CN) 6 、Na 3 Co(CN) 6 、K 3 Fe(CN) 6 、Na 3 Fe(CN) 6 One or more of the following.
6. The method for preparing a transition metal electrocatalyst rich in twin structures according to claim 1, wherein in step 2, the continuous stirring is performed for a period of time ranging from 1 to 12 hours; the inert atmosphere is Ar or N 2 The method comprises the steps of carrying out a first treatment on the surface of the The carbonization treatment is specifically to heat up to 500-900 ℃ at a speed of 1-10 ℃/min and preserve heat for 0.5-5 hours.
7. The method for preparing a transition metal electrocatalyst rich in twin structures according to claim 1, wherein in step 3, H in the acidic solution + Concentration of ions0.1 to 7mol/L.
8. The method for preparing a transition metal electrocatalyst rich in twin structures according to claim 1, wherein in step 3, the temperature of the acid washing is from room temperature to 100 ℃, and the time of the acid washing is from 0.5 to 72 hours.
9. A transition metal electrocatalyst rich in twin structures prepared by the method of any one of claims 1 to 8, wherein the electrocatalyst uses carbon cladding and in-situ phase structure transformation to induce a large number of intra-crystalline twin structures when alloy particles of different components of the transition metal are carbonized at a certain temperature, and combines nitrogen doped carbon, metal atom doped carbon and alloy particles to form a multi-stage multi-site catalytic system.
10. Use of a transition metal electrocatalyst enriched in twin structures prepared by the method according to any one of claims 1 to 8 or a transition metal electrocatalyst enriched in twin structures according to claim 9, characterized in that the use of the electrocatalyst is in particular: accelerating the precipitation of oxygen, the reduction of oxygen and the precipitation of hydrogen in alkaline environments.
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CN117174884A (en) * 2023-11-02 2023-12-05 宁德时代新能源科技股份有限公司 Composite lithium supplementing material and preparation method thereof, positive electrode plate, battery and power utilization device

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117174884A (en) * 2023-11-02 2023-12-05 宁德时代新能源科技股份有限公司 Composite lithium supplementing material and preparation method thereof, positive electrode plate, battery and power utilization device

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