Electrocatalytic oxygen evolution catalyst and preparation method thereof
1. An electrocatalytic oxygen evolution catalyst, characterized by: comprises a nitrogen-doped carbon hollow polyhedron, wherein cobalt-cobaltous phosphide nano heterogeneous particles are loaded on the surface of the polyhedron.
2. The method of preparing an electrocatalytic oxygen evolution catalyst according to claim 1, characterized by comprising the steps of:
(1) synthesizing ZIF-8 at room temperature by using 2-methylimidazole as a ligand, zinc salt as a metal source and methanol as a solvent;
(2) dispersing ZIF-8 in methanol, adding a methanol solution of 2-methylimidazole and a methanol solution of cobalt salt, and obtaining a [email protected] ZIF-67 zinc-cobalt bimetallic core-shell structure metal organic framework material by an epitaxial growth method;
(3) carrying out heat treatment on the [email protected] ZIF-67 zinc-cobalt bimetal core-shell structure metal organic framework material and a phosphorus source in an inert atmosphere to obtain the nitrogen-doped carbon hollow polyhedral material loaded by cobalt-cobaltous phosphide nano heterogeneous particles.
3. The method for preparing an electrocatalytic oxygen evolution catalyst according to claim 2, characterized in that: in the step (3), the mass ratio of the [email protected] ZIF-67 zinc-cobalt bimetallic core-shell structure metal organic framework material to the phosphorus source is 1: 10-100.
4. The method for preparing an electrocatalytic oxygen evolution catalyst according to claim 2, characterized in that: the zinc salt is any one of zinc nitrate, zinc chloride or zinc sulfate.
5. The method for preparing an electrocatalytic oxygen evolution catalyst according to claim 2, characterized in that: the cobalt salt is any one of cobalt nitrate, cobalt chloride or cobalt sulfate.
6. The method for preparing an electrocatalytic oxygen evolution catalyst according to claim 2, characterized in that: the phosphorus source is triphenylphosphine.
7. The method for preparing an electrocatalytic oxygen evolution catalyst according to claim 2, characterized in that: in the step (3), the heat treatment temperature is 800-1000 ℃, and the heat treatment time is 60-120 min.
8. The method for preparing an electrocatalytic oxygen evolution catalyst according to claim 7, characterized in that: the heating rate is 2-10 ℃/min.
9. The method for preparing an electrocatalytic oxygen evolution catalyst according to claim 2, characterized in that: in the step (1), the molar ratio of the 2-methylimidazole to the zinc salt is 3-5: 1.
10. The method for preparing an electrocatalytic oxygen evolution catalyst according to claim 2, characterized in that: in the step (2), the molar ratio of the 2-methylimidazole to the cobalt salt is 3-5: 1.
Background
Currently, there is an increasing global demand for exploring new energy sources to replace conventional fossil fuels, against the background of excessive consumption of fossil fuels and severe environmental pollution. Oxygen Evolution Reaction (OER) is an important half-reaction in new energy conversion and storage devices such as metal-air batteries, water splitting systems, etc., but the process is slow in kinetics. Currently, some noble metal based catalysts (e.g., IrO)2、RuO2) The catalyst is the best catalyst for preparing oxygen by electrolyzing water, but the defects of high price and limited reserves seriously restrict the large-scale commercial use of the catalyst, and the development of other transition metal catalysts with low price, environmental friendliness and high efficiency is very critical in the long run.
In the face of such problems, transition metal alloys, oxides, nitrides, sulfides, phosphides, etc. are widely studied and applied to electrolytic water oxygen evolution reactions. However, in most conventional synthesis methods, the transition metal phosphide nanoparticles generally have the problems of overgrowth, aggregation, sintering and the like at high temperature, resulting in some disadvantages such as few active sites, low conductivity, poor durability and the like.
Disclosure of Invention
The purpose of the invention is as follows: one of the purposes of the invention is to provide an electrocatalytic oxygen evolution catalyst, wherein a carbon hollow polyhedron has the advantages of optimized surface electronic structure, more active sites, good conductivity, high catalytic activity and the like; the invention also aims to provide a preparation method of the electrocatalytic oxygen evolution catalyst, which is simple to operate and easy for large-scale production.
The technical scheme is as follows: the invention relates to an electrocatalytic oxygen evolution catalyst which comprises a nitrogen-doped carbon hollow polyhedron, wherein cobalt-cobaltous phosphide nano heterogeneous particles are loaded on the surface of the polyhedron.
Preferably, the preparation method of the electrocatalytic oxygen evolution catalyst specifically comprises the following steps:
(1) synthesizing ZIF-8 at room temperature by using 2-methylimidazole as a ligand, zinc salt as a metal source and methanol as a solvent;
(2) dispersing ZIF-8 in methanol, adding a methanol solution of 2-methylimidazole and a methanol solution of cobalt salt, and obtaining a [email protected] ZIF-67 zinc-cobalt bimetallic core-shell structure metal organic framework material by an epitaxial growth method;
(3) carrying out heat treatment on the [email protected] ZIF-67 zinc-cobalt bimetal core-shell structure metal organic framework material and a phosphorus source in an inert atmosphere to obtain the nitrogen-doped carbon hollow polyhedral material loaded by cobalt-cobaltous phosphide nano heterogeneous particles.
The zinc salt is selected from one of zinc nitrate, zinc chloride or zinc sulfate, the cobalt salt is selected from one of cobalt nitrate, cobalt chloride or cobalt sulfate, and the phosphorus source is triphenylphosphine.
In the step (1), the molar ratio of the 2-methylimidazole to the zinc salt is 3-5: 1; for example, when the molar ratio of the two is 15: 4, the concentration of the solution before mixing is 0.5000mol/L and 0.1333mol/L, respectively.
In the step (2), the molar ratio of the 2-methylimidazole to the cobalt salt is 3-5: 1; for example, the molar ratio of the two is 15: 4, and the concentrations in the solution before mixing are 0.5000mol/L and 0.1333mol/L, respectively.
In the step (3), the mass ratio of the [email protected] ZIF-67 zinc-cobalt bimetallic core-shell structure metal organic framework material to the phosphorus source is 1: 10-100; the heat treatment temperature is 800-1000 ℃, the heat treatment time is 60-120 min, specifically, a temperature programming method can be adopted, and the temperature rise rate is 2-10 ℃/min.
The material prepared by the preparation method is a nitrogen-doped carbon hollow polyhedral material loaded by cobalt-cobaltous phosphide nano heterogeneous particles, and the material has excellent application as an electrocatalytic oxygen evolution catalyst.
The invention principle is as follows: according to the preparation method, 2-methylimidazole is used as a ligand, zinc salt is used as a metal source, methanol is used as a solvent to synthesize ZIF-8 at room temperature, then a precursor [email protected] ZIF-67 zinc-cobalt bimetallic core-shell structure metal organic framework material is obtained through an epitaxial growth method, and a pyrolysis-phosphorization strategy is adopted to prepare a nitrogen-doped carbon hollow polyhedron loaded with cobalt-cobalt phosphide nano heterogeneous particles. The catalyst is a hollow dodecahedron and has regular shape. In addition, due to the synergistic effect between the cobalt-cobaltous phosphide nano heterogeneous particles and the hollow polyhedron in the N-doped carbon, the obtained catalyst has higher electrocatalytic activity and stability.
ZIF-67 is a suitable template for making a cobalt-based catalyst with a multi-level structure. In addition, the heterojunction interface engineering can enhance the synergistic effect, accelerate the charge transfer rate, optimize the adsorption and activation energy of the intermediate and form more catalytic active sites on the surface of the catalyst.
Compared with the product obtained by using ZIF-67 as the precursor, the product of the invention has more stable appearance, more obvious cavity and less possibility of agglomeration of particles; with the conventional phosphorous source NaH for synthesizing metal phosphide2PO2In contrast, the phosphating process of the present invention does not involve toxic phosphine gas (pH)3) And without the need for a multi-step process of carbonization or oxidation followed by phosphating.
Further, the nitrogen-doped carbon hollow polyhedron loaded by the cobalt-cobaltous phosphide nano heterogeneous particles prepared by the invention has the following advantages:
1) the hollow dodecahedron structure can provide more active sites, and is favorable for the transmission and diffusion of electrolyte;
2) the carbon material is compounded, so that the conductivity can be enhanced, the stability is improved, the agglomeration can be inhibited, and the active sites can be increased;
3) the catalyst composition is stable; the hollow dodecahedron has stable structure and durability, thereby having better electrochemical stability.
Has the advantages that:
1) according to the invention, a nitrogen-doped carbon hollow polyhedron loaded with cobalt-cobaltous phosphide nano heterogeneous particles is prepared by a pyrolysis-phosphorization [email protected] ZIF-67 precursor strategy which is simple and convenient and can realize large-scale production;
2) the reactants selected in the method are cheap and easy to obtain, the method has simple and feasible process, low cost and simple equipment, and can realize large-scale production;
3) the product obtained by the method has a hollow dodecahedron structure, is regular in shape, has the characteristics of more active sites, high electrocatalytic activity, high stability and the like, is a very potential electrolytic water oxygen evolution catalyst, and has wide application prospects in the future energy industry.
Drawings
Fig. 1 is an SEM image of nitrogen doped carbon hollow polyhedrons supported by cobalt-cobaltous phosphide nano-heterogeneous particles prepared by the method of example 1.
Fig. 2 is a low power TEM spectrum of nitrogen doped carbon hollow polyhedrons supported by cobalt-cobaltous phosphide nano-heterogeneous particles prepared by the method of example 1.
Fig. 3 is a high power TEM image of nitrogen doped carbon hollow polyhedra loaded with cobalt-cobaltous phosphide nano-heterogeneous particles prepared by the method of example 1.
FIG. 4 is the XRD results of example 1 and comparative example 1; fig. (a) is an XRD pattern of the nitrogen-doped carbon hollow polyhedron supported by cobalt-cobaltous phosphide nano-heterogeneous particles prepared by the method of example 1, and fig. (b) is an XRD pattern of the nitrogen-doped carbon hollow polyhedron supported by cobalt nanoparticles prepared by the method of comparative example 1.
Fig. 5 is an alkaline oxygen evolution performance test pattern of the cobalt-cobalt phosphide nano-heterogeneous particle-supported nitrogen-doped carbon hollow polyhedron prepared by the method of example 1 and the cobalt nanoparticle-supported nitrogen-doped carbon hollow polyhedron prepared by the method of comparative example 1.
Fig. 6 is an alkaline oxygen evolution cycle stability test pattern of nitrogen doped carbon hollow polyhedrons loaded with cobalt-cobaltous phosphide nano heterogeneous particles prepared by the method of example 1.
Fig. 7 is an alkaline oxygen evolution timing current test pattern of nitrogen doped carbon hollow polyhedrons loaded with cobalt-cobaltous phosphide nano-heterogeneous particles prepared by the method of example 1.
Detailed Description
The present invention will be described in further detail with reference to examples.
Example 1
A preparation method of a nitrogen-doped carbon hollow polyhedron loaded by cobalt-cobaltous phosphide nano heterogeneous particles comprises the following steps:
1) preparation of ZIF-8: 0.02mol of Zn (NO) is weighed3)2·6H2O and 0.075mol of 2-methylimidazole were dissolved in 150ml of methanol, respectively, sufficiently dissolved, and then 2-methyl group was dissolvedThe imidazole in methanol solution is poured with Zn (NO) dissolved3)2·6H2And stirring the mixture for 24 hours at room temperature in a methanol solution of O, and centrifugally drying to obtain ZIF-8.
2) Preparation of [email protected] ZIF-67: 0.5g of ZIF-8 was weighed out and dissolved in 100ml of methanol, followed by sufficient dissolution. Then 0.02mol Co (NO) is weighed3)2·6H2O and 0.075mol of 2-methylimidazole were dissolved in 150ml of methanol, respectively, and dissolved sufficiently. Will subsequently dissolve Co (NO)3)2·6H2And pouring the methanol solution of O into the methanol solution dissolved with the ZIF-8, pouring the methanol solution dissolved with the 2-methylimidazole into the mixed solution, stirring at room temperature for 24 hours, and centrifugally drying to obtain the [email protected] ZIF-67.
3) Preparing a nitrogen-doped carbon hollow polyhedron loaded by cobalt-cobaltous phosphide nano heterogeneous particles: according to the mass ratio of [email protected] ZIF-67 to triphenylphosphine of 1: 20, uniformly mixing triphenylphosphine and the powder prepared in the step 2), putting the mixture into a porcelain boat, heating to 950 ℃ by a program of 2 ℃/min under an inert atmosphere, carrying out heat treatment, keeping the temperature for 90min, and cooling to obtain a final product.
Example 2
A preparation method of a nitrogen-doped carbon hollow polyhedron loaded by cobalt-cobaltous phosphide nano heterogeneous particles comprises the following steps:
1) preparation of ZIF-8: 0.02mol of Zn (NO) is weighed3)2·6H2O and 0.075mol of 2-methylimidazole were dissolved in 150ml of methanol, respectively, sufficiently dissolved, and then the methanol solution in which 2-methylimidazole was dissolved was poured into a solution in which Zn (NO) was dissolved3)2·6H2And stirring the mixture for 24 hours at room temperature in a methanol solution of O, and centrifugally drying to obtain ZIF-8.
2) Preparation of [email protected] ZIF-67: 0.5g of ZIF-8 was weighed out and dissolved in 100ml of methanol, followed by sufficient dissolution. Then 0.02mol Co (NO) is weighed3)2·6H2O and 0.075mol of 2-methylimidazole were dissolved in 150ml of methanol, respectively, and dissolved sufficiently. Will subsequently dissolve Co (NO)3)2·6H2Pouring the methanol solution of O into the methanol solution dissolved with ZIF-8, and pouring the methanol solution dissolved with 2-methylimidazole into the upper partAnd stirring the mixed solution at room temperature for 24 hours, and centrifugally drying to obtain [email protected] ZIF-67.
3) Preparing a nitrogen-doped carbon hollow polyhedron loaded by cobalt-cobaltous phosphide nano heterogeneous particles: uniformly mixing triphenylphosphine and the powder prepared in the step 2) according to the mass ratio of [email protected] ZIF-67 to triphenylphosphine of 1: 10, placing the mixture in a porcelain boat, heating to 950 ℃ at a temperature of 2 ℃/min under an inert atmosphere for heat treatment, keeping the temperature for 90min, and cooling to obtain a final product.
Example 3
A preparation method of a nitrogen-doped carbon hollow polyhedron loaded by cobalt-cobaltous phosphide nano heterogeneous particles comprises the following steps:
1) preparation of ZIF-8: 0.02mol of Zn (NO) is weighed3)2·6H2O and 0.075mol of 2-methylimidazole were dissolved in 150ml of methanol, respectively, sufficiently dissolved, and then the methanol solution in which 2-methylimidazole was dissolved was poured into a solution in which Zn (NO) was dissolved3)2·6H2And stirring the mixture for 24 hours at room temperature in a methanol solution of O, and centrifugally drying to obtain ZIF-8.
2) Preparation of [email protected] ZIF-67: 0.5g of ZIF-8 was weighed out and dissolved in 100ml of methanol, followed by sufficient dissolution. Then 0.02mol Co (NO) is weighed3)2·6H2O and 0.075mol of 2-methylimidazole were dissolved in 150ml of methanol, respectively, and dissolved sufficiently. Will subsequently dissolve Co (NO)3)2·6H2And pouring the methanol solution of O into the methanol solution dissolved with the ZIF-8, pouring the methanol solution dissolved with the 2-methylimidazole into the mixed solution, stirring at room temperature for 24 hours, and centrifugally drying to obtain the [email protected] ZIF-67.
3) Preparing a nitrogen-doped carbon hollow polyhedron loaded by cobalt-cobaltous phosphide nano heterogeneous particles: uniformly mixing triphenylphosphine and the powder prepared in the step 2) according to the mass ratio of [email protected] ZIF-67 to triphenylphosphine of 1: 50, placing the mixture in a porcelain boat, raising the temperature to 950 ℃ by a program of 2 ℃/min under an inert atmosphere for heat treatment, keeping the temperature for 90min, and then cooling to obtain a final product.
Example 4
A preparation method of a nitrogen-doped carbon hollow polyhedron loaded by cobalt-cobaltous phosphide nano heterogeneous particles comprises the following steps:
1) preparation of ZIF-8: 0.02mol of Zn (NO) is weighed3)2·6H2O and 0.075mol of 2-methylimidazole were dissolved in 150ml of methanol, respectively, sufficiently dissolved, and then the methanol solution in which 2-methylimidazole was dissolved was poured into a solution in which Zn (NO) was dissolved3)2·6H2And stirring the mixture for 24 hours at room temperature in a methanol solution of O, and centrifugally drying to obtain ZIF-8.
2) Preparation of [email protected] ZIF-67: 0.5g of ZIF-8 was weighed out and dissolved in 100ml of methanol, followed by sufficient dissolution. Then 0.02mol Co (NO) is weighed3)2·6H2O and 0.075mol of 2-methylimidazole were dissolved in 150ml of methanol, respectively, and dissolved sufficiently. Will subsequently dissolve Co (NO)3)2·6H2And pouring the methanol solution of O into the methanol solution dissolved with the ZIF-8, pouring the methanol solution dissolved with the 2-methylimidazole into the mixed solution, stirring at room temperature for 24 hours, and centrifugally drying to obtain the [email protected] ZIF-67.
3) Preparing a nitrogen-doped carbon hollow polyhedron loaded by cobalt-cobaltous phosphide nano heterogeneous particles: uniformly mixing triphenylphosphine and the powder prepared in the step 2) according to the mass ratio of [email protected] ZIF-67 to triphenylphosphine of 1: 100, placing the mixture in a porcelain boat, heating to 950 ℃ at a temperature of 2 ℃/min under an inert atmosphere for heat treatment, keeping the temperature for 90min, and cooling to obtain a final product.
Example 5
A preparation method of a nitrogen-doped carbon hollow polyhedron loaded by cobalt-cobaltous phosphide nano heterogeneous particles comprises the following steps:
1) preparation of ZIF-8: 0.02mol of Zn (NO) is weighed3)2·6H2O and 0.075mol of 2-methylimidazole were dissolved in 150ml of methanol, respectively, sufficiently dissolved, and then the methanol solution in which 2-methylimidazole was dissolved was poured into a solution in which Zn (NO) was dissolved3)2·6H2And stirring the mixture for 24 hours at room temperature in a methanol solution of O, and centrifugally drying to obtain ZIF-8.
2) Preparation of [email protected] ZIF-67: 0.5g of ZIF-8 was weighed out and dissolved in 100ml of methanol, followed by sufficient dissolution. Then 0.02mol Co (NO) is weighed3)2·6H2O and 0.075mol of 2-methylimidazole were dissolved in 150ml of methanol, respectively, and dissolved sufficiently. Will subsequently dissolve Co (NO)3)2·6H2And pouring the methanol solution of O into the methanol solution dissolved with the ZIF-8, pouring the methanol solution dissolved with the 2-methylimidazole into the mixed solution, stirring at room temperature for 24 hours, and centrifugally drying to obtain the [email protected] ZIF-67.
3) Preparing a nitrogen-doped carbon hollow polyhedron loaded by cobalt-cobaltous phosphide nano heterogeneous particles: uniformly mixing triphenylphosphine and the powder prepared in the step 2) according to the mass ratio of [email protected] ZIF-67 to triphenylphosphine of 1: 20, placing the mixture in a porcelain boat, raising the temperature to 950 ℃ by a program of 5 ℃/min under an inert atmosphere for heat treatment, keeping the temperature for 90min, and then cooling to obtain a final product.
Example 6
A preparation method of a nitrogen-doped carbon hollow polyhedron loaded by cobalt-cobaltous phosphide nano heterogeneous particles comprises the following steps:
1) preparation of ZIF-8: 0.02mol of Zn (NO) is weighed3)2·6H2O and 0.075mol of 2-methylimidazole were dissolved in 150ml of methanol, respectively, sufficiently dissolved, and then the methanol solution in which 2-methylimidazole was dissolved was poured into a solution in which Zn (NO) was dissolved3)2·6H2And stirring the mixture for 24 hours at room temperature in a methanol solution of O, and centrifugally drying to obtain ZIF-8.
2) Preparation of [email protected] ZIF-67: 0.5g of ZIF-8 was weighed out and dissolved in 100ml of methanol, followed by sufficient dissolution. Then 0.02mol Co (NO) is weighed3)2·6H2O and 0.075mol of 2-methylimidazole were dissolved in 150ml of methanol, respectively, and dissolved sufficiently. Will subsequently dissolve Co (NO)3)2·6H2And pouring the methanol solution of O into the methanol solution dissolved with the ZIF-8, pouring the methanol solution dissolved with the 2-methylimidazole into the mixed solution, stirring at room temperature for 24 hours, and centrifugally drying to obtain the [email protected] ZIF-67.
3) Preparing a nitrogen-doped carbon hollow polyhedron loaded by cobalt-cobaltous phosphide nano heterogeneous particles: uniformly mixing triphenylphosphine and the powder prepared in the step 2) according to the mass ratio of [email protected] ZIF-67 to triphenylphosphine of 1: 20, placing the mixture in a porcelain boat, heating to 950 ℃ at a temperature of 10 ℃/min under an inert atmosphere for heat treatment, keeping the temperature for 90min, and cooling to obtain a final product.
Example 7
A preparation method of a nitrogen-doped carbon hollow polyhedron loaded by cobalt-cobaltous phosphide nano heterogeneous particles comprises the following steps:
1) preparation of ZIF-8: 0.02mol of Zn (NO) is weighed3)2·6H2O and 0.075mol of 2-methylimidazole were dissolved in 150ml of methanol, respectively, sufficiently dissolved, and then the methanol solution in which 2-methylimidazole was dissolved was poured into a solution in which Zn (NO) was dissolved3)2·6H2And stirring the mixture for 24 hours at room temperature in a methanol solution of O, and centrifugally drying to obtain ZIF-8.
2) Preparation of [email protected] ZIF-67: 0.5g of ZIF-8 was weighed out and dissolved in 100ml of methanol, followed by sufficient dissolution. Then 0.02mol Co (NO) is weighed3)2·6H2O and 0.075mol of 2-methylimidazole were dissolved in 150ml of methanol, respectively, and dissolved sufficiently. Will subsequently dissolve Co (NO)3)2·6H2And pouring the methanol solution of O into the methanol solution dissolved with the ZIF-8, pouring the methanol solution dissolved with the 2-methylimidazole into the mixed solution, stirring at room temperature for 24 hours, and centrifugally drying to obtain the [email protected] ZIF-67.
3) Preparing a nitrogen-doped carbon hollow polyhedron loaded by cobalt-cobaltous phosphide nano heterogeneous particles: uniformly mixing triphenylphosphine and the powder prepared in the step 2) according to the mass ratio of [email protected] ZIF-67 to triphenylphosphine of 1: 20, placing the mixture in a porcelain boat, heating to 800 ℃ at a temperature of 2 ℃/min under an inert atmosphere for heat treatment, keeping the temperature for 90min, and cooling to obtain a final product.
Example 8
A preparation method of a nitrogen-doped carbon hollow polyhedron loaded by cobalt-cobaltous phosphide nano heterogeneous particles comprises the following steps:
1) preparation of ZIF-8: 0.02mol of Zn (NO) is weighed3)2·6H2O and 0.075mol of 2-methylimidazole are dissolved in 150ml of methanol respectively and are mixed thoroughlyDissolving, and pouring the methanol solution dissolved with 2-methylimidazole into the solution dissolved with Zn (NO)3)2·6H2And stirring the mixture for 24 hours at room temperature in a methanol solution of O, and centrifugally drying to obtain ZIF-8.
2) Preparation of [email protected] ZIF-67: 0.5g of ZIF-8 was weighed out and dissolved in 100ml of methanol, followed by sufficient dissolution. Then 0.02mol Co (NO) is weighed3)2·6H2O and 0.075mol of 2-methylimidazole were dissolved in 150ml of methanol, respectively, and dissolved sufficiently. Will subsequently dissolve Co (NO)3)2·6H2And pouring the methanol solution of O into the methanol solution dissolved with the ZIF-8, pouring the methanol solution dissolved with the 2-methylimidazole into the mixed solution, stirring at room temperature for 24 hours, and centrifugally drying to obtain the [email protected] ZIF-67.
3) Preparing a nitrogen-doped carbon hollow polyhedron loaded by cobalt-cobaltous phosphide nano heterogeneous particles: uniformly mixing triphenylphosphine and the powder prepared in the step 2) according to the mass ratio of [email protected] ZIF-67 to triphenylphosphine of 1: 20, placing the mixture in a porcelain boat, raising the temperature to 850 ℃ by a program of 2 ℃/min under an inert atmosphere for heat treatment, keeping the temperature for 90min, and then cooling to obtain a final product.
Example 9
A preparation method of a nitrogen-doped carbon hollow polyhedron loaded by cobalt-cobaltous phosphide nano heterogeneous particles comprises the following steps:
1) preparation of ZIF-8: 0.02mol of Zn (NO) is weighed3)2·6H2O and 0.075mol of 2-methylimidazole were dissolved in 150ml of methanol, respectively, sufficiently dissolved, and then the methanol solution in which 2-methylimidazole was dissolved was poured into a solution in which Zn (NO) was dissolved3)2·6H2And stirring the mixture for 24 hours at room temperature in a methanol solution of O, and centrifugally drying to obtain ZIF-8.
2) Preparation of [email protected] ZIF-67: 0.5g of ZIF-8 was weighed out and dissolved in 100ml of methanol, followed by sufficient dissolution. Then 0.02mol Co (NO) is weighed3)2·6H2O and 0.075mol of 2-methylimidazole were dissolved in 150ml of methanol, respectively, and dissolved sufficiently. Will subsequently dissolve Co (NO)3)2·6H2Pouring the methanol solution of O into the methanol solution dissolved with ZIF-8, and dissolving 2-methylAnd pouring the methyl alcohol solution of the imidazole into the mixed solution, stirring for 24 hours at room temperature, and centrifugally drying to obtain the [email protected] ZIF-67.
3) Preparing a nitrogen-doped carbon hollow polyhedron loaded by cobalt-cobaltous phosphide nano heterogeneous particles: uniformly mixing triphenylphosphine and the powder prepared in the step 2) according to the mass ratio of [email protected] ZIF-67 to triphenylphosphine of 1: 20, placing the mixture in a porcelain boat, heating to 900 ℃ at a speed of 2 ℃/min under an inert atmosphere for heat treatment, keeping the temperature for 90min, and cooling to obtain a final product.
Example 10
A preparation method of a nitrogen-doped carbon hollow polyhedron loaded by cobalt-cobaltous phosphide nano heterogeneous particles comprises the following steps:
1) preparation of ZIF-8: 0.02mol of Zn (NO) is weighed3)2·6H2O and 0.075mol of 2-methylimidazole were dissolved in 150ml of methanol, respectively, sufficiently dissolved, and then the methanol solution in which 2-methylimidazole was dissolved was poured into a solution in which Zn (NO) was dissolved3)2·6H2And stirring the mixture for 24 hours at room temperature in a methanol solution of O, and centrifugally drying to obtain ZIF-8.
2) Preparation of [email protected] ZIF-67: 0.5g of ZIF-8 was weighed out and dissolved in 100ml of methanol, followed by sufficient dissolution. Then 0.02mol Co (NO) is weighed3)2·6H2O and 0.075mol of 2-methylimidazole were dissolved in 150ml of methanol, respectively, and dissolved sufficiently. Will subsequently dissolve Co (NO)3)2·6H2And pouring the methanol solution of O into the methanol solution dissolved with the ZIF-8, pouring the methanol solution dissolved with the 2-methylimidazole into the mixed solution, stirring at room temperature for 24 hours, and centrifugally drying to obtain the [email protected] ZIF-67.
3) Preparing a nitrogen-doped carbon hollow polyhedron loaded by cobalt-cobaltous phosphide nano heterogeneous particles: uniformly mixing triphenylphosphine and the powder prepared in the step 2) according to the mass ratio of [email protected] ZIF-67 to triphenylphosphine of 1: 20, placing the mixture in a porcelain boat, heating to 1000 ℃ at a temperature of 2 ℃/min under an inert atmosphere for heat treatment, keeping the temperature for 90min, and cooling to obtain a final product.
Example 11
A preparation method of a nitrogen-doped carbon hollow polyhedron loaded by cobalt-cobaltous phosphide nano heterogeneous particles comprises the following steps:
1) preparation of ZIF-8: 0.02mol of Zn (NO) is weighed3)2·6H2O and 0.075mol of 2-methylimidazole were dissolved in 150ml of methanol, respectively, sufficiently dissolved, and then the methanol solution in which 2-methylimidazole was dissolved was poured into a solution in which Zn (NO) was dissolved3)2·6H2And stirring the mixture for 24 hours at room temperature in a methanol solution of O, and centrifugally drying to obtain ZIF-8.
2) Preparation of [email protected] ZIF-67: 0.5g of ZIF-8 was weighed out and dissolved in 100ml of methanol, followed by sufficient dissolution. Then 0.02mol Co (NO) is weighed3)2·6H2O and 0.075mol of 2-methylimidazole were dissolved in 150ml of methanol, respectively, and dissolved sufficiently. Will subsequently dissolve Co (NO)3)2·6H2And pouring the methanol solution of O into the methanol solution dissolved with the ZIF-8, pouring the methanol solution dissolved with the 2-methylimidazole into the mixed solution, stirring at room temperature for 24 hours, and centrifugally drying to obtain the [email protected] ZIF-67.
3) Preparing a nitrogen-doped carbon hollow polyhedron loaded by cobalt-cobaltous phosphide nano heterogeneous particles: uniformly mixing triphenylphosphine and the powder prepared in the step 2) according to the mass ratio of [email protected] ZIF-67 to triphenylphosphine of 1: 20, placing the mixture in a porcelain boat, heating to 950 ℃ at a temperature of 2 ℃/min under an inert atmosphere for heat treatment, keeping the temperature for 60min, and cooling to obtain a final product.
Example 12
A preparation method of a nitrogen-doped carbon hollow polyhedron loaded by cobalt-cobaltous phosphide nano heterogeneous particles comprises the following steps:
1) preparation of ZIF-8: 0.02mol of Zn (NO) is weighed3)2·6H2O and 0.075mol of 2-methylimidazole were dissolved in 150ml of methanol, respectively, sufficiently dissolved, and then the methanol solution in which 2-methylimidazole was dissolved was poured into a solution in which Zn (NO) was dissolved3)2·6H2And stirring the mixture for 24 hours at room temperature in a methanol solution of O, and centrifugally drying to obtain ZIF-8.
2) Preparation of [email protected] ZIF-67: weighing 0.5g ZIF-8 was dissolved in 100ml methanol and dissolved sufficiently. Then 0.02mol Co (NO) is weighed3)2·6H2O and 0.075mol of 2-methylimidazole were dissolved in 150ml of methanol, respectively, and dissolved sufficiently. Will subsequently dissolve Co (NO)3)2·6H2And pouring the methanol solution of O into the methanol solution dissolved with the ZIF-8, pouring the methanol solution dissolved with the 2-methylimidazole into the mixed solution, stirring at room temperature for 24 hours, and centrifugally drying to obtain the [email protected] ZIF-67.
3) Preparing a nitrogen-doped carbon hollow polyhedron loaded by cobalt-cobaltous phosphide nano heterogeneous particles: uniformly mixing triphenylphosphine and the powder prepared in the step 2) according to the mass ratio of [email protected] ZIF-67 to triphenylphosphine of 1: 20, placing the mixture in a porcelain boat, heating to 950 ℃ at a temperature of 2 ℃/min under an inert atmosphere for heat treatment, keeping the temperature for 120min, and cooling to obtain a final product.
Comparative example 1
[email protected] ZIF-67 was prepared in the same manner as in the first and second steps of example 1, except that the third step of phosphating was not carried out in this example, specifically:
1) preparation of ZIF-8: 0.02mol of Zn (NO) is weighed3)2·6H2O and 0.075mol of 2-methylimidazole were dissolved in 150ml of methanol, respectively, sufficiently dissolved, and then the methanol solution in which 2-methylimidazole was dissolved was poured into a solution in which Zn (NO) was dissolved3)2·6H2And stirring the mixture for 24 hours at room temperature in a methanol solution of O, and centrifugally drying to obtain ZIF-8.
2) Preparation of [email protected] ZIF-67: 0.5g of ZIF-8 was weighed out and dissolved in 100ml of methanol, followed by sufficient dissolution. Then 0.02mol Co (NO) is weighed3)2·6H2O and 0.075mol of 2-methylimidazole were dissolved in 150ml of methanol, respectively, and dissolved sufficiently. Will subsequently dissolve Co (NO)3)2·6H2And pouring the methanol solution of O into the methanol solution dissolved with the ZIF-8, pouring the methanol solution dissolved with the 2-methylimidazole into the mixed solution, stirring at room temperature for 24 hours, and centrifugally drying to obtain the [email protected] ZIF-67.
3) Preparing a nitrogen-doped carbon hollow polyhedron loaded by cobalt nanoparticles: putting the powder prepared in the step 2) into a porcelain boat, heating to 950 ℃ by a program of 2 ℃/min under an inert atmosphere, carrying out heat treatment, keeping the temperature for 90min, and then cooling to obtain the nitrogen-doped carbon hollow polyhedron loaded with the cobalt nanoparticles.
The samples prepared in the above examples and comparative examples are physically characterized by means of TEM, HRTEM, SEM, XRD and the like. From the SEM (fig. 1) and low power TEM (fig. 2) spectra, it can be seen that the cobalt-cobaltous phosphide nano-heterogeneous particle supported nitrogen-doped carbon hollow polyhedral catalyst prepared according to the method described in example 1 is a hollow dodecahedral structure, which can provide more active sites and facilitate electrolyte transport and diffusion. As can be seen from the further enlarged HRTEM (FIG. 3) spectrum, Co-Co2The lattice stripe distances of the N-doped carbon hollow polyhedron loaded by the P nano heterogeneous particles are respectively 0.178nm and 0.271nm, which respectively correspond to the (200) crystal face and the Co crystal face of the Co phase2The (200) crystal plane of the P phase. FIG. 4(a) is a nitrogen doped carbon hollow polyhedron XRD pattern carried by cobalt-cobaltous phosphide nano-heterogeneous particles prepared according to example 1, the diffraction peaks of which are compared with those of Co (JCPDS, 15-0806) and Co (JCPDS, 15-0806) by comparison with a standard pattern2The standard cards of P (JCPDS, 32-0306) are completely coincided, and the successful formation of a cobalt-cobaltous phosphide nano heterogeneous interface is proved; fig. 4(b) is a nitrogen doped carbon hollow polyhedron XRD pattern carried by cobalt nanoparticles prepared according to comparative example 1, which shows a pure Co phase without phosphating. FIG. 5 is Co-Co2P, Co oxygen evolution Performance test, Co-Co2The nitrogen-doped carbon hollow polyhedral catalyst loaded by the P nano heterogeneous particles reaches 10mAcm-2Only 267mV of overpotential is needed, which is obviously superior to the nitrogen-doped carbon hollow polyhedral catalyst loaded by non-phosphorized Co nano particles. FIG. 6 is Co-Co2The result of the cycle stability test of the P nano heterogeneous particle loaded nitrogen-doped carbon hollow polyhedral catalyst shows that the performance of the catalyst is not basically attenuated after 1000 cycles of cycle. FIG. 7 is Co-Co2The timing current test of the P nano heterogeneous particle loaded nitrogen-doped carbon hollow polyhedral catalyst shows that the performance of the catalyst is not substantially attenuated after the timing current test after 10 hours. The results show that the material acts asThe electrolytic water oxygen evolution catalyst has wide application prospect.
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