CN112536055A - Nitrogen-doped carbon-coated cobaltosic oxide nanowire monolithic catalyst and preparation method thereof - Google Patents
Nitrogen-doped carbon-coated cobaltosic oxide nanowire monolithic catalyst and preparation method thereof Download PDFInfo
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- UBEWDCMIDFGDOO-UHFFFAOYSA-N cobalt(2+);cobalt(3+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[O-2].[Co+2].[Co+3].[Co+3] UBEWDCMIDFGDOO-UHFFFAOYSA-N 0.000 title claims abstract description 105
- 239000003054 catalyst Substances 0.000 title claims abstract description 70
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims abstract description 69
- 229910052799 carbon Inorganic materials 0.000 title claims abstract description 69
- 239000002070 nanowire Substances 0.000 title claims abstract description 42
- 238000002360 preparation method Methods 0.000 title abstract description 13
- 239000013543 active substance Substances 0.000 claims abstract description 16
- 239000002245 particle Substances 0.000 claims abstract description 10
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 44
- 238000010438 heat treatment Methods 0.000 claims description 29
- 229910052757 nitrogen Inorganic materials 0.000 claims description 22
- 229910017052 cobalt Inorganic materials 0.000 claims description 21
- 239000010941 cobalt Substances 0.000 claims description 21
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 claims description 21
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 21
- 238000006243 chemical reaction Methods 0.000 claims description 20
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- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 16
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- UFMZWBIQTDUYBN-UHFFFAOYSA-N cobalt dinitrate Chemical compound [Co+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O UFMZWBIQTDUYBN-UHFFFAOYSA-N 0.000 claims description 4
- XFLNVMPCPRLYBE-UHFFFAOYSA-J tetrasodium;2-[2-[bis(carboxylatomethyl)amino]ethyl-(carboxylatomethyl)amino]acetate;tetrahydrate Chemical compound O.O.O.O.[Na+].[Na+].[Na+].[Na+].[O-]C(=O)CN(CC([O-])=O)CCN(CC([O-])=O)CC([O-])=O XFLNVMPCPRLYBE-UHFFFAOYSA-J 0.000 claims description 4
- 229910052734 helium Inorganic materials 0.000 claims description 3
- 239000001307 helium Substances 0.000 claims description 3
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- 238000011065 in-situ storage Methods 0.000 claims description 3
- GPKIXZRJUHCCKX-UHFFFAOYSA-N 2-[(5-methyl-2-propan-2-ylphenoxy)methyl]oxirane Chemical compound CC(C)C1=CC=C(C)C=C1OCC1OC1 GPKIXZRJUHCCKX-UHFFFAOYSA-N 0.000 claims description 2
- 229910019131 CoBr2 Inorganic materials 0.000 claims description 2
- 229910021580 Cobalt(II) chloride Inorganic materials 0.000 claims description 2
- 229910021582 Cobalt(II) fluoride Inorganic materials 0.000 claims description 2
- 229910021584 Cobalt(II) iodide Inorganic materials 0.000 claims description 2
- ZJRWDIJRKKXMNW-UHFFFAOYSA-N carbonic acid;cobalt Chemical compound [Co].OC(O)=O ZJRWDIJRKKXMNW-UHFFFAOYSA-N 0.000 claims description 2
- AVWLPUQJODERGA-UHFFFAOYSA-L cobalt(2+);diiodide Chemical compound [Co+2].[I-].[I-] AVWLPUQJODERGA-UHFFFAOYSA-L 0.000 claims description 2
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- 239000011149 active material Substances 0.000 abstract description 2
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- 238000004458 analytical method Methods 0.000 description 4
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- 229910021641 deionized water Inorganic materials 0.000 description 4
- 238000001027 hydrothermal synthesis Methods 0.000 description 4
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- 239000000843 powder Substances 0.000 description 4
- 239000010453 quartz Substances 0.000 description 4
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 4
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- UEUXEKPTXMALOB-UHFFFAOYSA-J tetrasodium;2-[2-[bis(carboxylatomethyl)amino]ethyl-(carboxylatomethyl)amino]acetate Chemical compound [Na+].[Na+].[Na+].[Na+].[O-]C(=O)CN(CC([O-])=O)CCN(CC([O-])=O)CC([O-])=O UEUXEKPTXMALOB-UHFFFAOYSA-J 0.000 description 3
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- 238000003917 TEM image Methods 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
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- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 2
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- 241000018646 Pinus brutia Species 0.000 description 1
- KJTLSVCANCCWHF-UHFFFAOYSA-N Ruthenium Chemical compound [Ru] KJTLSVCANCCWHF-UHFFFAOYSA-N 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
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- 230000009471 action Effects 0.000 description 1
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- 238000010981 drying operation Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- 238000002354 inductively-coupled plasma atomic emission spectroscopy Methods 0.000 description 1
- 229910052741 iridium Inorganic materials 0.000 description 1
- GKOZUEZYRPOHIO-UHFFFAOYSA-N iridium atom Chemical compound [Ir] GKOZUEZYRPOHIO-UHFFFAOYSA-N 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 239000002086 nanomaterial Substances 0.000 description 1
- 239000002105 nanoparticle Substances 0.000 description 1
- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen group Chemical group [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 0.000 description 1
- -1 nitrogen-containing compound Chemical class 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
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- 239000000758 substrate Substances 0.000 description 1
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Images
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J27/00—Catalysts comprising the elements or compounds of halogens, sulfur, selenium, tellurium, phosphorus or nitrogen; Catalysts comprising carbon compounds
- B01J27/24—Nitrogen compounds
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
- B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
- B01J23/74—Iron group metals
- B01J23/75—Cobalt
-
- B01J35/398—
Abstract
Disclosed is a monolithic catalyst comprising a carrier and an active material supported on the carrier; the active substance comprises nitrogen-doped carbon nanowires wrapping cobaltosic oxide particles. The application also discloses a preparation method of the monolithic catalyst. The cobaltosic oxide nanowire in the monolithic catalyst is wrapped by the nitrogen-doped carbon layer, so that the monolithic catalyst is good in product quality, high in conductivity and long in service life.
Description
Technical Field
The application relates to an integral catalyst and a preparation method of the integral nitrogen-doped carbon-coated cobaltosic oxide nanowire catalyst, belonging to the field of material preparation.
Background
Cobalt is a common transition metal, and compared with precious metals such as gold, platinum, ruthenium, iridium and the like, the cobalt has the advantages of richer reserves, lower price and certain catalytic performance, so that the cobalt becomes a popular material in the field of catalysis. However, pure metallic cobalt has low catalytic efficiency, catalytic performance is downstream in known materials, and cobaltosic oxide in a high oxidation state shows excellent catalytic activity in a plurality of catalytic reactions. Researches show that the surface defects, charge distribution and microscopic morphology of the cobaltosic oxide are regulated and controlled by doping modification, coating a shell or preparing a nano material, so that the catalytic efficiency of the cobaltosic oxide can be further improved, the stability of the cobaltosic oxide in a catalytic reaction is enhanced, and the service life of the catalyst is prolonged.
At present, most of cobaltosic oxide catalysts are in powder or nanoparticle structures, and the cobaltosic oxide catalysts are used directly as catalysts and have the problems of difficult dispersion and separation, uneven mass transfer and contact in the catalytic reaction process and the like; adding a binder to form a bulk material would increase cost and decrease catalytic activity. Therefore, the cobaltosic oxide active structure with controllable components and morphology directly grows on the catalyst carrier, and has important theoretical and practical significance.
Disclosure of Invention
According to one aspect of the present application, a monolithic catalyst is provided.
The monolithic catalyst is characterized by comprising a carrier and an active substance loaded on the carrier;
the active substance comprises nitrogen-doped carbon nanowires wrapping cobaltosic oxide particles.
Optionally, the active substance is grown in situ on the carrier surface.
Optionally, the morphology of the active substance is dendritic formed by nitrogen-doped carbon nanowires wrapping cobaltosic oxide particles.
Optionally, the carrier is selected from at least one of foamed metal, foamed carbon and carbon fiber cloth;
the particle size of the cobaltosic oxide particles is 3-10 nm;
the diameter of the nanowire is 40-60 nm;
the length of the nanowire is 500-2000 nm;
the molar content of nitrogen element in the active substance is 0.5-2%; the molar content of carbon element in the active substance is 20-40%; the molar content of the cobalt element in the active substance is 5-10%.
Optionally, the upper limit of the molar content of nitrogen element in the active substance is selected from 1%, 1.5% or 2%; the lower limit is selected from 0.5%, 1% or 1.5%.
Optionally, the upper limit of the molar content of cobalt element in the active material is selected from 6%, 7%, 8%, 9% or 10%; the lower limit is selected from 5%, 6%, 7%, 8% or 9%.
On the other hand, the application provides a preparation method of the monolithic nitrogen-doped carbon-coated cobaltosic oxide nanowire catalyst which is grown in situ on the carrier, is simple to prepare, low in cost, strong in catalytic performance, long in service life and easy to separate.
The preparation method of the monolithic catalyst is characterized by comprising the following steps of:
s100: obtaining an aqueous solution containing a cobalt source, a nitrogen source and a carbon source;
s200: immersing the carrier in the aqueous solution, and heating for reaction to obtain a precursor;
s300: and heating the precursor in the atmosphere of protective gas for reaction to obtain the monolithic catalyst.
Optionally, in the step S100, the molar ratio of cobalt in the cobalt source, nitrogen in the nitrogen source, and carbon in the carbon source to water in the aqueous solution is 1: 3-10: 1.5-50: 600 to 1200.
Optionally, the cobalt source is selected from CoF2、CoCl2、CoBr2、CoI2、CoCO3、Co(NO3)2、CoSO4At least one of;
the nitrogen source is at least one selected from urea and ethylene diamine tetraacetic acid tetrasodium;
the carbon source is at least one of urea and ethylene diamine tetraacetic acid tetrasodium.
Optionally, the temperature of the heating reaction in the step S200 is 110 ℃ to 160 ℃, and the time of the heating reaction is 8 to 24 hours;
step S200 is: immersing the carrier in the aqueous solution, heating for reaction, washing and drying to obtain a precursor;
the washing is as follows: washing with water and ethanol for 2-3 times in sequence;
the drying conditions are as follows: drying for 8-12 h at 60-80 ℃.
Optionally, the protective gas in step S300 is at least one selected from nitrogen, argon and helium;
the flow rate of the protective gas is 100 mL/min-180 mL/min.
Optionally, the temperature of the heating reaction in step S300 is 300 ℃ to 400 ℃, and the time of the heating reaction is 0.5h to 1 h.
Alternatively, the conditions of the heating reaction in step S300 are: heating from room temperature to 300-400 ℃ at the speed of 4-8 ℃/min, keeping the temperature for 0.5-1 h, and cooling to room temperature at the speed of 2-3 ℃/min.
The beneficial effects that this application can produce include:
1) the preparation method of the monolithic catalyst provided by the application is simple, the raw materials are easy to obtain, the yield is high, and the requirements on equipment and technology are low.
2) The application provides an integral catalyst, integral nitrogen-doped carbon parcel cobaltosic oxide nanowire catalyst have macroscopic view and hierarchical structure, can provide the intensity and the effective mass transfer passageway of reactant that are fit for practical application, and carbon cladding design can obstruct acid-base to the corruption that exposes the metal, prolongs the life of catalyst, constructs the confinement space simultaneously, and nitrogen-doped can promote carbon surface local electron cloud density, promotes the catalytic performance. Compared with cobalt-based powder catalyst, the catalyst is easier to separate after use.
3) According to the preparation method of the integral nitrogen-doped carbon-coated cobaltosic oxide nanowire catalyst, the catalyst prepared by the method is high in catalysis efficiency, strong in catalysis stability, long in service life and easy to separate from a product after being used.
Drawings
Fig. 1 is an XRD spectrum of the monolithic nitrogen-doped carbon-coated cobaltosic oxide nanowire catalyst and its surface exfoliation components, prepared in example 1 of the present application;
fig. 2 is a scanning electron microscope image of the monolithic nitrogen-doped carbon-coated cobaltosic oxide nanowire catalyst prepared in example 1 of the present application; wherein, (a) is 5 μm in scale bar, (b) is 500 μm in scale bar, and (c) is 50 μm in scale bar;
FIG. 3 is a transmission electron microscope image of the surface exfoliation of the monolithic nitrogen-doped carbon-coated cobaltosic oxide nanowire catalyst prepared in example 1 of the present application; wherein (a) is 0.2 μm in scale bar, (b) is 100nm in scale bar, and (c) is 5nm in scale bar;
FIG. 4 is an X photoelectron spectrum of the monolithic nitrogen-doped carbon-coated cobaltosic oxide nanowire catalyst prepared in example 1 of the present application;
fig. 5 is a STEM element distribution diagram of the monolithic nitrogen-doped carbon-coated tricobalt tetraoxide nanowire catalyst prepared in example 1 of the present application; wherein, (a) is carbon element, (b) is nitrogen element, (c) is oxygen element, and (d) is cobalt element.
Detailed Description
The present application will be described in detail with reference to examples, but the present application is not limited to these examples.
Unless otherwise specified, the raw materials and catalysts in the examples of the present application were all purchased commercially.
The analysis method in the examples of the present application is as follows:
XRD analysis was performed using a Bruker D8 DISCOVER X-ray diffractometer with Cu as the target.
SEM analysis was performed using a HITACHI S-4800 scanning electron microscope at 8.0 kV.
TEM analysis was performed using a FEI F20 transmission electron microscope at 200 kV.
Using Kratos AXIS ULTRADLDThe device uses Al as a target material to carry out X photoelectron spectroscopy analysis.
ICP analysis was performed using a SPECTRA ARCOS ICP-OES instrument.
The monolithic catalyst comprises a carrier and an active substance loaded on the carrier;
the active substance comprises nitrogen-doped carbon nanowires wrapping cobaltosic oxide particles.
The preparation method of the monolithic catalyst comprises the following steps:
s100, preparing a solution: mixing Co (NO)3)2Mixing with nitrogen-carbon compound in a certain proportion, adding water to prepareA solution; wherein said Co (NO)3)2The mol ratio of the nitrogen-containing compound to the carbon-containing compound is 1: 1.5-1: 5. Preferably, as an implementation mode, the nitrogen-containing and carbon-containing compound is one or two of urea and ethylenediaminetetraacetic acid tetrasodium salt.
In the present application, the concentration of the prepared solution is not particularly limited. In order to prepare the integral nitrogen-doped carbon-coated cobaltosic oxide nanowire catalyst with excellent performance, enhance the catalytic stability and prolong the service life, preferably Co (NO)3)2The molar ratio of the water to the water is 1: 600-1: 1200.
S200, hydrothermal reaction: and (4) placing the solution obtained in the step (S100) into a reaction kettle, adding carriers such as foam metal or foam carbon or carbon fiber cloth and the like, preserving the temperature for 8-24 h at 110-160 ℃, washing and drying to obtain a precursor.
In step S200, the carrier such as metal foam, carbon foam, or carbon fiber cloth is not particularly limited. In order to prepare a uniform catalyst and improve the catalytic efficiency, the specification of the carrier such as foamed metal or foamed carbon or carbon fiber cloth is preferably satisfied to be immersed in the solution.
In the step, a precursor is obtained through hydrothermal reaction, wherein the hydrothermal temperature is 110-160 ℃, and the heating time is 8-24 h.
The surface of the precursor obtained by the reaction is covered with a small amount of precipitate, and in order to remove the precipitate, a washing operation is required, preferably, the washing method comprises the following steps: and washing the precursor for 2-3 times by using water and ethanol in sequence.
After the precursor is washed, drying operation is needed to remove residual water and ethanol. Preferably, the drying conditions are: drying for 8-12 h at 60-80 ℃.
S300, carbonizing: and (4) placing the precursor obtained in the step (S200) in a heating furnace, introducing protective gas, preserving the temperature for 0.5-1 h at the temperature of 300-400 ℃, and cooling to obtain the integral nitrogen-doped carbon-coated cobaltosic oxide nanowire catalyst.
The target integral nitrogen-doped carbon-coated cobaltosic oxide nanowire catalyst is obtained through a carbonization process, wherein in order to facilitate the introduction of protective gas, the heating furnace is preferably a tubular furnace with a built-in quartz tube or corundum tube, and the protective gas is preferably one or more of nitrogen, argon and helium. The flow rate of the shielding gas is not excessively large, and the flow rate is preferably 100mL/min to 180 mL/min. Under the flow, the ablation of the product can be prevented, the purity of the product can be ensured, and the physical and chemical properties of the product are improved.
In step S300, the heating mode is a one-step heating mode, and in order to ensure the product quality, the heating speed should not be too fast, and preferably, the temperature control process of the heating furnace is as follows: heating from room temperature to 300-400 ℃ at the speed of 4-8 ℃/min, keeping the temperature for 0.5-1 h, and cooling to room temperature at the speed of 2-3 ℃/min.
In the application, the nitrogen and carbon-containing compound has the effects of simultaneously providing an N source and a C source, forming a nitrogen-doped carbon wrapping layer, reducing the corrosion of acid and alkali to cobalt and prolonging the service life of the catalyst.
It should be noted that, in the finally obtained monolithic nitrogen-doped carbon-coated cobaltosic oxide nanowire catalyst, the loading amount of the Co element and the doping concentration of the N atom can be regulated and controlled by the proportion of the raw materials at the beginning.
The preparation method of the integral nitrogen-doped carbon-coated cobaltosic oxide nanowire catalyst adopts a simple operation method, has low requirements on equipment and technology, uses common chemical raw materials as raw materials, and has low cost; the catalyst obtained by the method has uniform N atom distribution, and the Co element loading capacity and the N atom doping concentration are adjustable, so that the catalyst can meet the application under different conditions; the integral nitrogen-doped carbon-coated cobaltosic oxide nanowire catalyst obtained by the invention has high content of doped carbon with good conductivity, and has combined action with the cobaltosic oxide nanowire, so that the catalyst has high conductivity and long service life; in addition, compared with the nano powder catalyst, the monolithic catalyst prepared by the method has more mass transfer pore channels and is easier to separate from a catalytic product after being used.
Example 1
(1) 0.584g of Co (NO) was added to the beaker3)2·6H2O, 0.6g of urea, 36mL of deionized water,stirring at room temperature. Wherein, Co (NO)3)2In a molar ratio of 1:5 with urea, Co (NO)3)2The molar ratio to water was 1: 1000.
(2) And (2) transferring the solution prepared in the step (1) to a 100mL reaction kettle, adding a foamed nickel carrier, immersing the foamed nickel carrier in the solution, putting the solution into an oven to react for 8h at 120 ℃, taking out the solution, sequentially washing the solution with water and ethanol for 2 times, putting the solution into a beaker, and putting the beaker into the oven to dry the solution for 12h at 60 ℃ to obtain a precursor.
(3) Placing the precursor obtained in the step (2) in a quartz boat of a tube furnace, sealing, and introducing high-purity nitrogen as a whole-process protective gas, wherein the flow rate of the nitrogen is 150 mL/min; and (3) ventilating for 30min, heating to 350 ℃ at the speed of 5 ℃/min, preserving the heat for 0.5h, cooling to room temperature at the speed of 3 ℃/min, and obtaining the product, namely the integral nitrogen-doped carbon-coated cobaltosic oxide nanowire catalyst grown on the foamed nickel, which is marked as sample 1.
Example 2
(1) 0.584g of Co (NO) was added to the beaker3)2·6H2O, 0.2g of urea and 36mL of deionized water, and stirring the mixture evenly at room temperature. Wherein, Co (NO)3)2In a molar ratio of 1:1.67 to urea, Co (NO)3)2The molar ratio to water was 1: 1000.
(2) Same as example 1
(3) The sample obtained is designated sample 2 in the same manner as in example 1.
Compared with the example 1, the quality of the urea in the raw materials used in the example is changed, the other preparation conditions are not changed, and the nitrogen-doped carbon coating layer of the finally obtained catalyst becomes thinner and the nitrogen doping amount is reduced along with the reduction of the quality of the urea.
Example 3
(1) Same as example 1
(2) And (2) transferring the solution prepared in the step (1) to a 100mL reaction kettle, adding a foamed nickel carrier, immersing the foamed nickel carrier in the solution, putting the solution into an oven to react for 8h at 140 ℃, taking out the solution, sequentially washing the solution for 2 times by using water and ethanol, putting the solution into a beaker, and putting the beaker into the oven to dry for 12h at 60 ℃ to obtain a precursor.
(3) The sample obtained is designated sample 3 in the same manner as in example 1.
Compared with the example 1, the temperature of the hydrothermal reaction used in the present example is changed, the other preparation conditions are not changed, and the diameter of the finally obtained nitrogen-doped carbon-coated cobaltosic oxide nanowire catalyst nanowire is increased with the increase of the temperature of the hydrothermal reaction.
Example 4
(1) 0.3g Co (NO) was added to the beaker3)2·6H2O, 0.124g of urea and 20mL of deionized water, and stirring the mixture uniformly at room temperature. Wherein, Co (NO)3)2In a 1:2 molar ratio with urea, Co (NO)3)2The molar ratio to water was 1: 1078.
(2) And (2) transferring the solution prepared in the step (1) to a 100mL reaction kettle, adding carbon fiber cloth, immersing the carbon fiber cloth in the solution, putting the solution into an oven to react for 12h at 120 ℃, taking out the solution, sequentially washing the solution for 2 times by using water and ethanol, putting the solution into a beaker, and putting the beaker into the oven to dry for 12h at 60 ℃ to obtain a precursor.
(3) Placing the precursor obtained in the step (2) in a quartz boat of a tube furnace, sealing, and introducing high-purity argon as a whole-process protective gas, wherein the flow rate of nitrogen is 120 mL/min; and (3) ventilating for 40min, heating to 350 ℃ at the speed of 5 ℃/min, preserving the heat for 0.5h, cooling to room temperature at the speed of 2 ℃/min, and obtaining an integral nitrogen-doped carbon-coated cobaltosic oxide nanowire catalyst growing on the carbon fiber cloth, wherein the product is marked as a sample 4.
Example 5
(1) 0.584g of Co (NO) was added to the beaker3)2·6H2O、0.8g Na4EDTA·4H2O, 36mL of deionized water, and stirring at room temperature. Wherein Co (NO)3)2With Na4EDTA·4H2O molar ratio of 1:1.77, Co (NO)3)2The molar ratio to water was 1: 1000.
(2) And (2) transferring the solution prepared in the step (1) to a 100mL reaction kettle, adding a carbon foam carrier, immersing the carbon foam carrier in the solution, putting the solution into an oven to react for 8h at 130 ℃, taking out the solution, sequentially washing the solution for 2 times by using water and ethanol, putting the solution into a beaker, and putting the beaker into the oven to dry for 12h at 60 ℃ to obtain a precursor.
(3) Placing the precursor obtained in the step (2) in a quartz boat of a tube furnace, sealing, and introducing high-purity argon as a whole-process protective gas, wherein the flow rate of nitrogen is 140 mL/min; and ventilating for 30min, heating to 400 ℃ at the speed of 5 ℃/min, preserving the heat for 0.5h, cooling to room temperature at the speed of 3 ℃/min, and obtaining the product, namely the integral nitrogen-doped carbon-coated cobaltosic oxide nanowire catalyst growing on the foam carbon, which is marked as sample 5.
Example 6
XRD test is carried out on the samples 1-5 and the nitrogen-doped carbon-coated cobaltosic oxide nano powder mechanically stripped from the carrier. Fig. 1 is an XRD spectrogram of sample 1, nitrogen-doped carbon-coated cobaltosic oxide nanowire powder mechanically stripped from nickel foam, and a sample before stripping, and it can be seen from the XRD spectrogram that the stripped powder sample has distinct diffraction peaks at 2-Theta angles of 31.27 (220), 36.85 (311), 44.81 (400), 59.36 (511), and 65.24 (440), and is attributed to characteristic peaks of cobaltosic oxide, while the un-stripped sample is entirely reflected as a nickel foam signal because XRD signals of the nitrogen-doped carbon-coated cobaltosic oxide nanowire layer grown on nickel foam are far less than the signal intensity of the substrate metal nickel, and only has a weak signal at 2-Theta 36.85.
XRD tests on samples 2-3 and the nitrogen-doped carbon-coated cobaltosic oxide nano powder mechanically stripped from the foamed nickel show only the difference of peak intensity and uniform characteristic peaks compared with the sample shown in figure 1.
Sample 4 and the nitrogen-doped carbon-coated cobaltosic oxide nano powder mechanically stripped from the carbon fiber cloth are subjected to XRD test, and the stripped nitrogen-doped carbon-coated cobaltosic oxide nano powder in the figure 1 only have the difference of peak intensity, and the characteristic peaks are uniform.
Sample 5 and the nitrogen-doped carbon-coated cobaltosic oxide nano powder mechanically stripped from the foam carbon are subjected to XRD test, and the stripped nitrogen-doped carbon-coated cobaltosic oxide nano powder in the figure 1 only have the difference of peak intensity, and the characteristic peaks are uniform.
Example 7
And performing SEM and TEM tests on the samples 1-5 and the nitrogen-doped carbon-coated cobaltosic oxide nano powder mechanically stripped from the carrier. Fig. 2 is a scanning electron microscope image of the monolithic nitrogen-doped carbon-coated cobaltosic oxide nanowire catalyst grown on the foamed nickel obtained in example 1, and it can be seen from the image that the microstructure of the catalyst is in a shape of a pine branch. Fig. 3 is a transmission electron microscope image of the mechanically exfoliated nitrogen-doped carbon-coated cobaltosic oxide nanowire catalyst obtained in the example, wherein the diameter of the catalyst nanowire is about 50nm, and the length of the catalyst nanowire is more than 500 nm.
SEM images and TEM images of samples 2 to 3 and nitrogen-doped carbon-coated cobaltosic oxide nano powder mechanically stripped from a carrier are similar to those of sample 1, and only the diameters of the nanowires are different.
SEM images and TEM images of samples 4-5 and nitrogen-doped carbon-coated cobaltosic oxide nano powder mechanically stripped from the carrier are similar to those of sample 1, and only the difference of the carrier is different from that of the diameter of the nanowire.
Example 8
And (3) carrying out X photoelectron spectroscopy test on the nitrogen-doped carbon-coated cobaltosic oxide nano powder mechanically stripped from the carrier by the samples 1 to 5. FIG. 4 is an X photoelectron spectrum of sample 1 in example 1, and the results show that the percentage contents of the elements on the surface of the catalyst are respectively C (37.65 at%), N (1.08 at%), Co (7.27 at%) and carrier nickel element, and the total cobalt content measured by ICP (inductively coupled plasma mass spectrometer) is 20.1 at%, thus proving that cobalt is actually Co3O4The form is wrapped by a nitrogen-doped carbon layer.
And (3) mechanically stripping the samples 1-5 from the carrier, and carrying out STEM test on the nitrogen-doped carbon-coated cobaltosic oxide nano powder to obtain a STEM element distribution diagram. FIG. 5 is a STEM element distribution diagram of sample 1 in example 1, showing that carbon element, nitrogen element, oxygen element and cobalt element are uniformly distributed.
Although the present application has been described with reference to a few embodiments, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the application as defined by the appended claims.
Claims (10)
1. A monolithic catalyst, characterized in that the monolithic catalyst comprises a carrier and an active substance supported on the carrier;
the active substance comprises nitrogen-doped carbon nanowires wrapping cobaltosic oxide particles.
2. The monolithic catalyst according to claim 1, wherein the active species is grown in situ on the support surface.
3. The monolithic catalyst of claim 1, wherein the morphology of the active species is dendritic from nitrogen-doped carbon nanowires encapsulating the tricobalt tetraoxide particles.
4. The monolithic catalyst according to claim 1, wherein the support is selected from at least one of a metal foam, a carbon fiber cloth;
the particle size of the cobaltosic oxide particles is 3-10 nm;
the diameter of the nanowire is 40-60 nm;
the length of the nanowire is 500-2000 nm;
the molar content of nitrogen element in the active substance is 0.5-2%; the molar content of carbon element in the active substance is 20-40%; the molar content of the cobalt element in the active substance is 5-10%.
5. A method for preparing a monolithic catalyst, comprising the steps of:
s100: obtaining an aqueous solution containing a cobalt source, a nitrogen source and a carbon source;
s200: immersing the carrier in the aqueous solution, and heating for reaction to obtain a precursor;
s300: and heating the precursor in the atmosphere of protective gas for reaction to obtain the monolithic catalyst.
6. The process for preparing a monolithic catalyst according to claim 5,
in the step S100, the molar ratio of cobalt element in the cobalt source, nitrogen element in the nitrogen source, carbon element in the carbon source and water in the aqueous solution is 1: 3-10: 1.5-50: 600 to 1200.
7. The process for preparing a monolithic catalyst according to claim 5,
the cobalt source is selected from CoF2、CoCl2、CoBr2、CoI2、CoCO3、Co(NO3)2、CoSO4At least one of;
the nitrogen source is at least one selected from urea and ethylene diamine tetraacetic acid tetrasodium;
the carbon source is at least one of urea and ethylene diamine tetraacetic acid tetrasodium.
8. The process for preparing a monolithic catalyst according to claim 5,
the heating reaction temperature in the step S200 is 110-160 ℃, and the heating reaction time is 8-24 h;
step S200 is: immersing the carrier in the aqueous solution, heating for reaction, washing and drying to obtain a precursor;
the washing is as follows: washing with water and ethanol for 2-3 times in sequence;
the drying conditions are as follows: drying for 8-12 h at 60-80 ℃.
9. The process for preparing a monolithic catalyst according to claim 5,
in the step S300, the protective gas is at least one selected from nitrogen, argon and helium;
the flow rate of the protective gas is 100 mL/min-180 mL/min;
in the step S300, the heating reaction temperature is 300-400 ℃, and the heating reaction time is 0.5-1 h.
10. The process for preparing a monolithic catalyst according to claim 5,
the conditions of the heating reaction in step S300 are: heating from room temperature to 300-400 ℃ at the speed of 4-8 ℃/min, keeping the temperature for 0.5-1 h, and cooling to room temperature at the speed of 2-3 ℃/min.
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| CN114105217B (en) * | 2021-10-28 | 2023-11-03 | 合肥国轩高科动力能源有限公司 | Carbon-coated cobaltosic oxide negative electrode material and preparation method and application thereof |
| CN115041189B (en) * | 2022-05-09 | 2024-03-01 | 山西潞宝兴海新材料有限公司 | Ruthenium-cobalt alloy ammonia synthesis catalyst with mesoporous carbon confinement, and preparation method and application thereof |
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