CN109112341B - Preparation method of hierarchical porous nickel-cobalt alloy-carbon composite block material with electromagnetic wave absorption performance - Google Patents
Preparation method of hierarchical porous nickel-cobalt alloy-carbon composite block material with electromagnetic wave absorption performance Download PDFInfo
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Abstract
The invention discloses a preparation method of a hierarchical porous nickel-cobalt alloy-carbon composite block material with electromagnetic wave absorption performance, which comprises the following steps: uniformly mixing deionized water and glycerol, adding polyacrylic acid, fully stirring until the polyacrylic acid is completely dispersed and dissolved, adding a nickel source and a cobalt source which are used as precursors, hydrolyzing, adding a gel accelerator, and stirring; and sealing the obtained sol, performing gelation treatment, drying the obtained block gel, placing the obtained block xerogel in an inert atmosphere tube furnace, heating to 400-1000 ℃, and preserving the temperature for 100-300 min to obtain the hierarchical porous nickel-cobalt alloy-carbon composite block material. The hierarchical porous nickel-cobalt alloy-carbon composite block material prepared by the method has stable wave-absorbing performance.
Description
Technical Field
The invention relates to a preparation method of a hierarchical porous nickel-cobalt alloy-carbon composite block material with electromagnetic wave absorption performance.
Background
In the process of human progress and social development, along with the development of electronic information technology and the popularization and application of electronic products, the living standard of human beings is greatly improved, and the living quality is obviously improved. The electronic products bring great convenience to daily life of people and bring great troubles. This is because, with the wide application of electronic products and electrical appliances such as mobile phones and computers, we can be subjected to the radiation of electromagnetic waves of various frequencies and energies in the ordinary living environment. Too high a level of electromagnetic radiation can exceed the levels that the body and environment can withstand, creating electromagnetic pollution. Electromagnetic pollution has become an emerging source of pollution threatening human life due to its severity. A large number of medical cases show that excessive electromagnetic wave radiation threatens human health and influences the normal operation of the nervous system, the endocrine system and the self-circulation system of people. Therefore, materials capable of absorbing electromagnetic waves in a frequency range that they come into contact with in the daily life are being developed for wide use in the civil field. The wave-absorbing material can efficiently absorb electromagnetic radiation and has the characteristics of higher efficiency and universality compared with an electromagnetic shielding material, so that the wave-absorbing material becomes a main means for preventing and treating electromagnetic pollution.
The nano nickel-cobalt alloy material has special surface magnetism and catalytic performance, and has wide application in the fields of high-density magnetic storage materials, high-quality magnetic fluid materials, electromagnetic shielding, wave-absorbing materials and the like.
The wave absorbing performance of the nickel-cobalt alloy is closely related to the chemical composition, the tissue structure, the granularity and the shape of the nickel-cobalt alloy. The smaller the particle size of the material crystal grain, the larger the specific surface area, and the higher the absorption of electromagnetic wave.
The traditional method for preparing the nickel-cobalt alloy mainly comprises the methods of a mechanical alloy method, an oxalate pyrolysis method, an ultrasonic radiation method, a hydrothermal reduction method, electrodeposition and the like, and the nickel-cobalt alloy prepared by the traditional preparation method has large particle size, more impurities, difficult stable control of morphology and difficult solution of wave absorption stability.
Disclosure of Invention
The invention aims to provide a preparation method of a hierarchical porous nickel-cobalt alloy-carbon composite block material with electromagnetic wave absorption performance, which can be used in the field of wave absorption.
In order to solve the technical problem, the invention provides a preparation method of a hierarchical porous nickel-cobalt alloy-carbon composite block material with electromagnetic wave absorption performance, which comprises the following steps:
A) weighing 1.0-4.0 mL of deionized water, adding into 1.0-3.0 mL of glycerol, and magnetically stirring until the mixture is uniformly mixed;
B) adding 1.0-4.0 g of polyacrylic acid into the solution obtained in the step A), and fully stirring until the polyacrylic acid is completely dispersed and dissolved;
C) adding 0.5-3.0 g of nickel source as precursor and 0.5-4.0 g of cobalt source as precursor into the homogeneous solution obtained in the step B), and hydrolyzing for 3-5 h under stirring (at this time, the precursor can be completely hydrolyzed to generate hydroxide corresponding to the precursor);
D) adding 1.0-2.5 ml of gel accelerator into the liquid (clear transparent solution) obtained in the step C), and stirring for 20-30 min;
E) sealing the sol obtained in the step D), and then placing the sol in a drying oven at 40-60 ℃ for gelation for 48 +/-2 hours;
F) drying the block gel obtained in the step E) for 48 +/-2 hours at 50-60 ℃ (in an oven);
G) and F) placing the block xerogel obtained in the step F) in an inert atmosphere tube furnace, heating to 400-1000 ℃ at a heating rate of 0.5-5 ℃/min, and preserving heat for 100-300 min to obtain the hierarchical porous nickel-cobalt alloy-carbon composite block material.
The improvement of the preparation method of the hierarchical porous nickel-cobalt alloy-carbon composite block material of the invention comprises the following steps:
the molecular weight of polyacrylic acid adopted in the step B) is 3000, 5000, 50000 and 10000;
the nickel source of the step C) is NiCl2·6H2O、Ni(NO3)2·6H2O, cobalt source is CoCl2·6H2O、Co(NO3)2·6H2O；
The gel accelerator used in step D) is propylene oxide, formamide.
The preparation method of the hierarchical porous nickel-cobalt alloy-carbon composite block material is further improved as follows: in the step D), the gel accelerator is added in a dropwise manner, and the temperature of the system is controlled not to exceed 60 ℃ in the dropwise adding process.
The method prepares a porous block of nickel-cobalt composite hydroxide by synthesizing raw materials such as a phase separating agent (polyacrylic acid), a solvent (deionized water and glycerol), a precursor, a gel promoter and the like; and (3) performing heat treatment in an inert atmosphere, decomposing the organic matter into carbon under the action of high temperature, reducing the carbon formed by cracking the hydroxide into metal, and finally obtaining the hierarchical porous nickel-cobalt alloy-carbon composite block material.
Compared with the prior art, the invention has the following technical advantages:
1) the phase separation agent is introduced into the micron-sized macropores, so that the nickel-cobalt alloy can keep a certain appearance size and is convenient to store and transport; the gel accelerator can slowly increase the pH value of the system and control the formation of the skeleton;
2) on the premise of ensuring the alloy block, the component change of nickel and cobalt in any proportion can be realized;
3) the particle size of the alloy can be reasonably controlled by heat treatment at different temperatures in inert atmosphere;
4) the micropores formed after the heat treatment and the mesopores are combined with a macroporous structure generated by phase separation to form a macroporous-mesopore-micropore hierarchical porous nickel-cobalt alloy block material;
5) the production process and equipment are simple, and industrialization is easy to realize;
6) no harmful substance is produced in the production process.
In conclusion, the sol-gel and phase separation-accompanied wet chemical method is adopted in the invention to ensure the uniformity of the nickel-cobalt alloy material, the size of the nickel-cobalt alloy can be controlled by the heat treatment temperature, and the pore size distribution and the specific surface area depend on the proportion of the starting raw materials. Therefore, the prepared nickel-cobalt alloy has stable wave-absorbing performance.
Drawings
The following describes embodiments of the present invention in further detail with reference to the accompanying drawings.
FIG. 1 is a physical appearance diagram (a) and scanning electron micrographs (b-f) of the porous silica bulk aerogel prepared in example 1; (b) the pictures of scanning electron microscope (50000 times lower) after the porous nickel-cobalt alloy block is heat treated at 400 ℃, 500 ℃, 600 ℃, 800 ℃ and 1000 ℃ can see that the block has continuous through macropores (about 1 μm).
FIG. 2 shows the wave-absorbing properties of the porous Ni-Co alloy prepared in example 1, wherein the wave-absorbing properties are the best when the heat treatment is carried out at 800 degrees, the minimum reflection loss is-19 dB, and the effective absorption (dB is less than-10 dB) bandwidth reaches 2 GHz.
FIG. 3 shows the nitrogen adsorption/desorption curve (upper graph) and BJH pore size of the porous Ni-Co alloy block prepared in example 2Distribution curve (lower panel). The BET calculation result shows that the specific surface area of the porous nickel-cobalt alloy block body subjected to heat treatment at the temperature of 600 ℃ can reach 167m2·g-1。
Fig. 4 is an XRD pattern of the porous nickel-cobalt alloy bulk prepared in example 3, with the peak position of the (111) crystal plane of the nickel-cobalt alloy between that of pure cobalt and pure nickel, indicating that the nickel-cobalt alloy can be formed under heat treatment at 800 ℃. In the figure, pure Co, Ni-Co, and pure Ni are shown in this order from top to bottom.
Detailed Description
The invention will be further described with reference to specific examples, but the scope of the invention is not limited thereto.
In step D) of the following cases, propylene oxide was added in the form of dropwise addition, and the temperature of the system was controlled not to exceed 60 ℃ during the dropwise addition.
Example 1, a method for preparing a hierarchical porous nickel-cobalt alloy-carbon composite block material sequentially includes the following steps:
A) weighing 1.2mL of deionized water, adding into 2.4mL of glycerol, and magnetically stirring until 2 are completely and uniformly mixed;
B) adding 4.0g of polyacrylic acid (50000) into the solution obtained in the step A), and fully stirring until the polyacrylic acid is completely dispersed and dissolved;
C) adding a nickel source (NiCl) serving as a precursor into the uniform solution obtained in the step B)2·6H2O)0.713g, cobalt source (CoCl)2·6H2O)1.426g, and the hydrolysis was carried out for 5 hours with stirring, at which time the precursor was completely hydrolyzed.
D) Adding 1.76ml of propylene oxide into the clear transparent solution obtained in the step C), and stirring for 20-30 min;
E) sealing the sol obtained in the step D) and placing the sol in an oven at the temperature of 40-60 ℃ for gelling for 48 hours;
F) drying the block gel obtained in the step E) in an oven at 50-60 ℃ for 48 hours;
G) and F) placing the block xerogel obtained in the step F) in an inert atmosphere tube furnace, and respectively heating to the following 5 temperature points at the heating rate of 2.5 ℃/min: preserving the heat at 400 ℃, 500 ℃, 600 ℃, 800 ℃ or 1000 ℃ for 100min, thus correspondingly preparing the 5 kinds of hierarchical porous nickel-cobalt alloy-carbon composite material.
A) weighing 2.4mL of deionized water, adding into 1.2mL of glycerol, and magnetically stirring until the solution is completely and uniformly mixed;
B) adding 4.0g of polyacrylic acid (50000) into the liquid obtained in the step A), and fully stirring until the polyacrylic acid is completely dispersed and dissolved;
C) adding a precursor nickel source (NiCl) into the uniform solution obtained in the step B)2·6H2O)0.713g, cobalt source (CoCl)2·6H2O)1.426g, stirring for 5h until the precursor is completely hydrolyzed;
D) adding 1.76ml of propylene oxide into the clear transparent solution obtained in the step C), and stirring for 20-30 min;
E) sealing the sol obtained in the step D) and placing the sol in an oven at the temperature of 40-60 ℃ for gelling for 48 hours;
F) drying the block gel obtained in the step E) in an oven at 50-60 ℃ for 48 hours;
G) and F) placing the block xerogel obtained in the step F) into an inert atmosphere tubular furnace, and heating to the following 4 temperature points at the heating rate of 2.5 ℃/min: and preserving the heat at 400 ℃, 600 ℃, 800 ℃ or 1000 ℃ for 100min to correspondingly prepare 4 hierarchical porous nickel-cobalt alloy-carbon composite materials.
A) weighing 1.2mL of deionized water, adding the deionized water into 2.4mL of glycerol, and magnetically stirring until the solution is completely and uniformly mixed;
B) adding 4.0g of polyacrylic acid (50000) into the liquid obtained in the step A), and fully stirring until the polyacrylic acid is completely dispersed and dissolved;
C) adding a precursor nickel source (NiCl) into the uniform solution obtained in the step B)2·6H2O)2.16g, nickel source (NiCl)2·6H2O)0.713g, cobalt source (CoCl)2·6H2O)1.426g, cobalt source (Co)Cl2·6H2O)2.16g is stirred for 5 hours until the precursor is completely hydrolyzed;
D) adding 1.76ml of propylene oxide into the clear transparent solution obtained in the step C), and stirring for 20-30 min;
E) sealing the sol obtained in the step D) and placing the sol in an oven at the temperature of 40-60 ℃ for gelling for 48 hours;
F) drying the block gel obtained in the step E) in an oven at 50-60 ℃ for 48 hours;
G) and F) placing the block xerogel obtained in the step F) into an inert atmosphere tubular furnace, heating to 800 ℃ at the heating rate of 2.5 ℃/min, and preserving the temperature for 100min to obtain the hierarchical porous nickel-cobalt alloy-carbon composite material.
Finally, it is also noted that the above-mentioned lists merely illustrate a few specific embodiments of the invention. It is obvious that the invention is not limited to the above embodiments, but that many variations are possible. All modifications which can be derived or suggested by a person skilled in the art from the disclosure of the present invention are to be considered within the scope of the invention.
Claims (5)
1. The preparation method of the hierarchical porous nickel-cobalt alloy-carbon composite block material with electromagnetic wave absorption performance is characterized by comprising the following steps:
A) weighing 1.0-4.0 mL of deionized water, adding into 1.0-3.0 mL of glycerol, and magnetically stirring until the mixture is uniformly mixed;
B) adding 1.0-4.0 g of polyacrylic acid into the solution obtained in the step A), and fully stirring until the polyacrylic acid is completely dispersed and dissolved;
C) adding 0.5-3 g of nickel source serving as a precursor and 0.5-4.0 g of cobalt source serving as a precursor into the uniform solution obtained in the step B), and hydrolyzing for 3-5 h under stirring;
D) adding 1.0-2.5 ml of gel accelerator into the solution obtained in the step C), and stirring for 20-30 min;
E) sealing the sol obtained in the step D), and then gelatinizing the sol at the temperature of 40-60 ℃ for 48 +/-2 hours;
F) drying the block gel obtained in the step E) at 50-60 ℃ for 48 +/-2 hours;
G) and F) placing the block xerogel obtained in the step F) in an inert atmosphere tube furnace, heating to 400-1000 ℃ at a heating rate of 0.5-5 ℃/min, and preserving heat for 100-300 min to obtain the hierarchical porous nickel-cobalt alloy-carbon composite block material.
2. The method of making a hierarchical porous nickel-cobalt alloy-carbon composite bulk material of claim 1, wherein: the molecular weight of polyacrylic acid adopted in the step B) is 3000, 5000, 50000 and 10000.
3. The method of making a hierarchical porous nickel-cobalt alloy-carbon composite bulk material of claim 2, wherein: the nickel source of the step C) is NiCl2·6H2O、Ni(NO3)2·6H2O, cobalt source is CoCl2·6H2O、Co(NO3)2·6H2O。
4. The method of making a hierarchical porous nickel-cobalt alloy-carbon composite bulk material of claim 3, wherein: the gel accelerator used in step D) is propylene oxide, formamide.
5. The method of making a hierarchical porous nickel-cobalt alloy-carbon composite bulk material of claim 4, wherein: in the step D), the gel accelerator is added in a dropwise manner, and the temperature of the system is controlled not to exceed 60 ℃ in the dropwise adding process.
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| CN105665027A (en) * | 2015-12-29 | 2016-06-15 | 四川大学 | Preparation method of high-dispersing supported metal nano catalyst |
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