CN108585054B - VO (volatile organic compound)2(M)-CoFe2O4Composite material and preparation method thereof - Google Patents
VO (volatile organic compound)2(M)-CoFe2O4Composite material and preparation method thereof Download PDFInfo
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Abstract
The invention discloses a VO2(M)‑CoFe2O4The composite material comprises monoclinic phase VO2And CoFe of spinel structure2O4And the monoclinic phase VO2And CoFe of the spinel structure2O4All are nanospheres with a particle size of 30-90 nm. The preparation method is that CoFe is mixed2O4Dissolving vanadium pentoxide, hydrogen peroxide and polyvinylpyrrolidone into deionized water to prepare a reaction precursor solution; and then heating the reaction precursor solution to 180-250 ℃, preserving the heat for 1-4 days, cooling to room temperature, performing solid-liquid separation, cleaning and drying, and then placing in a vacuum annealing furnace for calcination. The invention has simple preparation method and low cost, can realize lower phase transition temperature, and simultaneously obtains visible light transmittance higher than 40% and solar energy regulation and control amplitude larger than 10%.
Description
Technical Field
The invention relates to the field of vanadium dioxide composite nano materials, in particular to VO2(M)-CoFe2O4Composite materials and methods for making the same.
Background
Vanadium dioxide (VO)2) There are six common crystal structures: VO (vacuum vapor volume)2(R)、VO2(M)、VO2(T)、VO2(A)、VO2(B) And VO2(C) In that respect Rutile type VO2(R) is a thermodynamically stable structure with a space group of P4/mmm. Metastable VO2(B) Has a laminated structure. VO (vacuum vapor volume)2(T) is a triclinic system. VO (vacuum vapor volume)2(M) is a monoclinic system, space group is P21/c, and lattice constant isβ -122.60 °. atomic coordinates V (0.2420.9750.025), O1 (0.10.210.20), and O2 (0.390.690.29).
Monoclinic phase vanadium dioxide (VO)2) Is a typical thermotropic phase change material. Conventional VO2The phase change from an insulator to metal can occur when the temperature of the material is raised to about 68 ℃, the phase change time is very short and is close to nanosecond level, parameters such as resistivity, infrared transmittance and the like before and after the phase change can all change remarkably, and the characteristic enables VO (volatile organic compounds)2The application of the intelligent window (the intelligent window is a light-adjusting functional device composed of a substrate such as glass or transparent plastic and a light-adjusting material, and the device can change the transparency or the color of the device under certain physical conditions (such as an electric field and temperature), so that the external heat radiation can be selectively absorbed and reflected, the internal heat diffusion can be prevented, and the purpose of adjusting the light intensity or the indoor temperature can be achieved). But currently VO will be2practical application to intelligent windows has at least the following difficulty that how to synthesize monoclinic phase VO at low cost2the method comprises the steps of firstly, controlling the phase change temperature to be close to the room temperature, and secondly, simultaneously obtaining the visible light transmittance higher than 40% and the solar energy regulation and control amplitude larger than 10%.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides a VO2(M)-CoFe2O4The composite material and the preparation method thereof have the advantages of simple preparation method, low cost, adjustable components and easiness in realization of large-scale production, can reduce the phase transition temperature, and greatly improve the visible light transmittance under the condition of not remarkably reducing the solar energy regulation and control amplitude, thereby realizing lower phase transition temperature and simultaneously obtaining the visible light transmittance higher than 40% and the solar energy regulation and control amplitude larger than 10%.
The purpose of the invention is realized by the following technical scheme:
VO (volatile organic compound)2(M)-CoFe2O4The composite material comprises monoclinic phase VO2And CoFe of spinel structure2O4And the monoclinic phase VO2And CoFe of the spinel structure2O4All are nanospheres with a particle size of 30-90 nm.
Preferably, the monoclinic phase VO2And CoFe of the spinel structure2O4Are all nanospheres with an average particle size of 70 nm.
Preferably, the monoclinic phase VO2And CoFe of the spinel structure2O4The molar ratio of (A) to (B) is 1-0.1: 0.01-1.
VO (volatile organic compound)2(M)-CoFe2O4The preparation method of the composite material comprises the following steps:
step A, according to CoFe2O4Vanadium pentoxide, hydrogen peroxide, polyvinylpyrrolidone and deionized water in a molar ratio of 0.01-1: 1-0.1: 0.02-0.4: 0.2-1: 30-100, and adding CoFe2O4Dissolving vanadium pentoxide, hydrogen peroxide and polyvinylpyrrolidone into deionized water, and mixing together to obtain a reaction precursor solution;
step B, placing the reaction precursor solution into an autoclave with a polytetrafluoroethylene inner container, placing the autoclave in an oven, heating the autoclave from room temperature to 180-250 ℃, preserving heat for 1-4 days, cooling the autoclave to room temperature, performing solid-liquid separation on substances in the autoclave, sequentially performing cleaning treatment and drying treatment on solids obtained by the solid-liquid separation, placing the autoclave in a vacuum annealing furnace for calcination at 250-500 ℃ for 1-2 hours, and thus obtaining the VO2(M)-CoFe2O4A composite material.
Preferably, the CoFe2O4The preparation method comprises the following steps: dissolving cobalt nitrate, ferric nitrate and polyethylene glycol into an alcohol solvent according to a molar ratio of 0.2-1: 0.4-2: 0.2-10: 200-1000, performing magnetic stirring, and then dropwise adding nitric acid into the stirred mixed solution until the pH value of the mixed solution is 1.5-2, so as to obtain a cobalt ferrite reaction precursor; stirring the cobalt ferrite reaction precursor at 60-120 ℃ until sol is formed; placing the sol in air until an orange gel is formed; drying the orange gel to form dry gel, calcining the dry gel at 400-900 ℃ for 2 hours, and grinding the dry gel into powderThereby producing CoFe2O4And (3) powder.
Preferably, the stirring speed of the magnetic stirring is 100-300 rpm/min, and the stirring time is 10-30 min.
Preferably, the solid-liquid separation is centrifugal separation, the rotating speed of the centrifugal separation is 7000-10000 r/min, and the centrifugal separation time is 3-10 min.
Preferably, the cleaning treatment is to alternately clean the solid obtained by solid-liquid separation for 7-9 times by using deionized water and ethanol or distilled water and ethanol.
Preferably, the drying treatment is to heat the solid object after the cleaning treatment at 50-80 ℃ for 3-4 hours.
VO (volatile organic compound)2(M)-CoFe2O4The application of the composite material is to use the VO2(M)-CoFe2O4Composite materials are used for "smart windows".
It can be seen from the above technical solutions provided by the present invention that the VO provided by the present invention2(M)-CoFe2O4The composite material is CoFe mixed according to a specific molar ratio2O4The vanadium pentoxide and vanadium pentoxide are used as raw materials, a hydrothermal method is adopted for reaction at 180-250 ℃, and then the reaction product is obtained by calcining at 250-500 ℃; the VO2(M)-CoFe2O4The composition of the composite material comprises monoclinic phase VO2And CoFe of spinel structure2O4And the monoclinic phase VO2And CoFe of the spinel structure2O4All the nanospheres are nanospheres with the particle size of 30-90 nm, and the average particle size of the nanospheres is 70 nm; such CoFe in the present invention2O4Has the characteristics of mild saturation magnetization, higher coercive force, large magnetic anisotropy constant, high thermal stability, chemical stability and the like, and CoFe2O4The wide bandgap semiconductor and VO2(M) compounding while simultaneously reacting on VO2The (M) material is subjected to controllable doping and defect modulation, and VO can be realized2The (M) base film forbidden band width can be regulated and controlled in a large range, the phase transition temperature can be reduced, and the regulation and control range of solar energy is not obviously reducedUnder the condition, the transmittance of visible light is greatly improved, so that the lower phase transition temperature can be realized, and meanwhile, the visible light transmittance higher than 40% and the solar energy regulation and control amplitude larger than 10% are obtained.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on the drawings without creative efforts.
FIG. 1 shows VO in comparative example 12(M) nanopowder and VO in examples 1-2 of the present invention2(M)-CoFe2O4X-ray diffraction pattern of the composite.
FIG. 2 shows VO in comparative example 12(M) nanopowder and VO in inventive example 12(M)-CoFe2O4Scanning electron micrographs (FESEM images) of the composite.
FIG. 3 shows VO in comparative example 1 by differential scanning calorimetry2(M) nanopowder and VO in examples 1-2 of the present invention2(M)-CoFe2O4And detecting the composite material to obtain a DSC curve comparison graph.
Detailed Description
The technical solutions in the embodiments of the present invention are clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without making any creative effort, shall fall within the protection scope of the present invention.
VO provided by the invention2(M)-CoFe2O4The composite material and the method for preparing the same are described in detail. Details which are not described in detail in the embodiments of the invention belong to the prior art which is known to the person skilled in the art.
VO (volatile organic compound)2(M)-CoFe2O4The composite material comprises monoclinic phase VO2And CoFe of spinel structure2O4And the monoclinic phase VO2And CoFe of the spinel structure2O4The molar ratio of (A) to (B) is 1-0.1: 0.01-1; the monoclinic phase VO2And CoFe of the spinel structure2O4All are nanospheres with the particle size of 30-90 nm, and the average particle size of the nanospheres is 70 nm. The VO2(M)-CoFe2O4The composite material can be used in the fields of intelligent windows, sensors, memory devices and the like.
Wherein the monoclinic phase VO2And CoFe of the spinel structure2O4The molar ratio of (A) to (B) is adjustable within the range of 1-0.1: 0.01-1.
In particular, the VO2(M)-CoFe2O4The preparation method of the composite material can firstly adopt a sol-gel method to prepare CoFe2O4The powder is prepared by a hydrothermal method and later-stage heat treatment; the method specifically comprises the following steps:
step a, according to cobalt nitrate (Co (NO)3)2·6H2O) iron nitrate (Fe (NO)3)3·9H2Dissolving cobalt nitrate, ferric nitrate and polyethylene glycol into the same alcohol solvent according to the molar ratio of 0.2-1: 0.4-2: 0.2-10: 200-1000, and performing magnetic stirring at the stirring speed of 100-300 rpm/min for 10-30 min to obtain a clear mixed solution; then, dropwise adding nitric acid into the stirred mixed solution until the pH value of the mixed solution is 1.5-2, thereby obtaining a cobalt ferrite reaction precursor; stirring the cobalt ferrite reaction precursor for 6 hours at the temperature of 60-120 ℃ until sol is formed; allowing the sol to stand in air for several days until an orange gel is formed; drying the orange gel to form dry glue (for example, drying the orange gel at 60 ℃ for 4 hours to form dry glue), then calcining the dry glue at 400-900 ℃ for 2 hours, and grinding the calcined glue into powder to obtain the CoFe2O4And (3) powder.
Step b, according to CoFe2O4Vanadium pentoxide (V)2O5) Hydrogen peroxide (H)2O2) Polyvinylpyrrolidone (PVP), deionized water (0.01-1: 1-0.1: 0.02-0.4: 0.2-1: 30-100) and CoFe2O4Vanadium pentoxide, hydrogen peroxide and polyvinylpyrrolidone are dissolved in deionized water and subjected to ultrasonic treatment to be mixed together, so that a reaction precursor solution is obtained.
Step c, placing the reaction precursor solution in an autoclave with a polytetrafluoroethylene inner container, screwing the autoclave, placing the autoclave in an oven, heating the autoclave from room temperature to 180-250 ℃, keeping the temperature for 1-4 days, then closing the power supply of the oven, naturally cooling the autoclave to room temperature, performing solid-liquid separation on substances in the autoclave (for example, the solid-liquid separation can adopt centrifugal separation, the rotating speed of the centrifugal separation is 7000-10000 r/min, and the centrifugal separation time is 3-10 min), sequentially performing cleaning treatment on solids obtained by the solid-liquid separation (for example, the cleaning treatment adopts deionized water and ethanol or distilled water and ethanol to perform 7-9 times of alternate cleaning on the solids obtained by the solid-liquid separation) and drying treatment (for example, the drying treatment adopts the solid obtained by the cleaning treatment to be placed at 50-80 ℃ for heating for 3-4 hours), then placing the mixture in a vacuum annealing furnace for calcination at the temperature of 250-500 ℃ for 1-2 hours to obtain the VO2(M)-CoFe2O4A composite material.
Compared with the prior art, the VO provided by the invention2(M)-CoFe2O4The composite material and the preparation method thereof have at least the following advantages:
(1) VO provided by the invention2(M)-CoFe2O4The composition of the composite material comprises monoclinic phase VO2And CoFe of spinel structure2O4And the monoclinic phase VO2And CoFe of the spinel structure2O4All are nanospheres with a particle size of 30-90 nm, and the nanospheres with a particle average size of 70 nm. CoFe in the invention2O4With mild saturation magnetizationBy using CoFe with high strength, high coercive force, large magnetic anisotropy constant, high thermal stability and chemical stability2O4The wide bandgap semiconductor and VO2(M) is compounded and regulated to realize VO2The (M) wide range regulation of the forbidden band width of the base film greatly improves the transmittance of visible light under the condition of not obviously reducing the regulation amplitude of solar energy, thereby realizing lower phase transition temperature and simultaneously obtaining the visible light transmittance higher than 40% and the regulation amplitude of solar energy larger than 10%.
(2) VO provided by the invention2(M)-CoFe2O4In the composite material, monoclinic phase VO2And CoFe of spinel structure2O4The molar ratio of (a) to (b) is adjustable within the range of 1-0.1: 0.01-1 and is accompanied by CoFe2O4The VO is increased2(M)-CoFe2O4The phase change endothermic peak of the composite material moves to low temperature, namely VO provided by the invention2(M)-CoFe2O4The composite material can reduce VO2The phase transition temperature of (a).
(3) VO provided by the invention2(M)-CoFe2O4The preparation method of the composite material has the advantages of simple process, easy operation, low cost and high yield, and is not only suitable for industrial large-scale production, but also easy for commercial application.
In conclusion, the embodiment of the invention has the advantages of simple preparation method, low cost, adjustable components and easy realization of large-scale production, can reduce the phase transition temperature, and can greatly improve the visible light transmittance under the condition of not remarkably reducing the solar energy regulation amplitude, thereby realizing lower phase transition temperature and simultaneously obtaining the visible light transmittance higher than 40% and the solar energy regulation amplitude larger than 10%.
In order to more clearly show the technical solutions and the technical effects provided by the present invention, the following embodiments are specific examples of the VO provided by the embodiments of the present invention2(M)-CoFe2O4The composite material and the method for preparing the same are described in detail.
Comparative example 1
VO (volatile organic compound)2The preparation method of the (M) nano powder can comprise the following steps:
step A1' according to vanadium pentoxide (V)2O5) Hydrogen peroxide (H)2O2) Dissolving vanadium pentoxide, hydrogen peroxide and polyvinylpyrrolidone into deionized water according to the molar ratio of 1:0.4:1:50 of polyvinylpyrrolidone (PVP) to deionized water, and carrying out ultrasonic treatment for 30min to mix the materials together, thereby obtaining a reaction precursor solution.
Step B1', placing the reaction precursor solution into an autoclave with a polytetrafluoroethylene inner container, screwing the autoclave tightly, placing the autoclave into an oven, heating the autoclave from room temperature to 219 ℃, preserving heat for 1 day, then closing the power supply of the oven, naturally cooling the autoclave to room temperature, performing centrifugal separation on substances in the autoclave, cleaning the solids obtained by the centrifugal separation, then placing the cleaned solids into the oven to dry for 3 hours at 60 ℃, and then placing the solids into a vacuum annealing furnace to calcine for 2 hours at 400 ℃, thereby obtaining VO2(M) a nano-powder.
Comparative example 2
VO (volatile organic compound)2The preparation method of the (M) nano powder can comprise the following steps:
step A2' according to vanadium pentoxide (V)2O5) Hydrogen peroxide (H)2O2) Dissolving vanadium pentoxide, hydrogen peroxide and polyvinylpyrrolidone into deionized water according to the molar ratio of 1:0.1:1:50 of polyvinylpyrrolidone (PVP) to deionized water, and carrying out ultrasonic treatment for 30min to mix the materials together, thereby obtaining a reaction precursor solution.
Step B2', placing the reaction precursor solution in an autoclave with a polytetrafluoroethylene inner container, screwing the autoclave, placing the autoclave in an oven, heating the autoclave from room temperature to 210 ℃, preserving heat for 2 days, then closing the power supply of the oven, naturally cooling the autoclave to room temperature, performing centrifugal separation on substances in the autoclave, cleaning the solids obtained by the centrifugal separation, placing the cleaned solids in a drying oven to dry for 4 hours at 60 ℃, and then placing the solids in a vacuum annealing furnace to 400 DEG CCalcining for 2 hours to prepare VO2(M) a nano-powder.
Comparative example 3
VO (volatile organic compound)2The preparation method of the (M) nano powder can comprise the following steps:
step A3' according to vanadium pentoxide (V)2O5) Hydrogen peroxide (H)2O2) Dissolving vanadium pentoxide, hydrogen peroxide and polyvinylpyrrolidone into deionized water according to the molar ratio of 1:0.05:1:50 of polyvinylpyrrolidone (PVP) to deionized water, and carrying out ultrasonic treatment for 10-30 min to mix the materials together, thereby obtaining a reaction precursor solution.
Step B3', placing the reaction precursor solution into an autoclave with a polytetrafluoroethylene inner container, screwing the autoclave tightly, placing the autoclave into an oven, heating the autoclave from room temperature to 198 ℃, preserving heat for 3 days, then closing the power supply of the oven, naturally cooling the autoclave to room temperature, carrying out centrifugal separation on substances in the autoclave, cleaning the solid obtained by centrifugal separation, placing the solid obtained after cleaning into a drying oven, drying the solid for 4 hours at 60 ℃, and then placing the solid into a vacuum annealing furnace, calcining the solid for 2 hours at 400 ℃, thereby obtaining VO2(M) a nano-powder.
Comparative example 4
VO (volatile organic compound)2The preparation method of the (M) nano powder can comprise the following steps:
step A4' according to vanadium pentoxide (V)2O5) Hydrogen peroxide (H)2O2) Dissolving vanadium pentoxide, hydrogen peroxide and polyvinylpyrrolidone into deionized water according to the molar ratio of 1:0.02:1:50 of polyvinylpyrrolidone (PVP) to deionized water, and carrying out ultrasonic treatment for 10-30 min to mix the materials together, thereby obtaining a reaction precursor solution.
Step B4', placing the reaction precursor solution in an autoclave with a polytetrafluoroethylene inner container, screwing the autoclave, placing the autoclave in an oven, heating the autoclave from room temperature to 180 ℃, preserving the heat for 4 days, then closing the power supply of the oven, naturally cooling the autoclave to room temperature, centrifugally separating the substances in the autoclave, and cleaning the solids obtained by centrifugal separationTreating, drying the solid matter in a drying oven at 60 deg.C for 4 hr, calcining in a vacuum annealing furnace at 400 deg.C for 2 hr to obtain VO2(M) a nano-powder.
Example 1
VO (volatile organic compound)2(M)-CoFe2O4The preparation method of the composite material can comprise the following steps:
step a1, according to cobalt nitrate (Co (NO)3)2·6H2O) iron nitrate (Fe (NO)3)3·9H2Dissolving cobalt nitrate, ferric nitrate and polyethylene glycol in the same alcohol solvent at a molar ratio of 0.2:0.4:1:300, and magnetically stirring for 30min to obtain a clear mixed solution; then, dropwise adding nitric acid into the stirred mixed solution until the pH value of the mixed solution is 2.0, thereby obtaining a cobalt ferrite reaction precursor; stirring the cobalt ferrite reaction precursor for 6 hours at 80 ℃ until sol is formed; allowing the sol to stand in air for several days until an orange gel is formed; the orange gel was dried at 60 ℃ for 4 hours to form a dry gel, and the dry gel was calcined at 700 ℃ for 2 hours and ground to a powder to produce CoFe2O4And (3) powder.
Step b1 according to CoFe2O4Vanadium pentoxide (V)2O5) Hydrogen peroxide (H)2O2) Polyvinylpyrrolidone (PVP) deionized water at a molar ratio of 0.5:1:0.1:1:50, CoFe2O4Dissolving the powder, vanadium pentoxide, hydrogen peroxide and polyvinylpyrrolidone into deionized water, and carrying out ultrasonic treatment for 30min to mix the materials together, thereby obtaining a reaction precursor solution.
Step c1, placing the reaction precursor solution in an autoclave with a polytetrafluoroethylene inner container, screwing the autoclave, placing the autoclave in an oven, heating the autoclave from room temperature to 220 ℃, preserving the heat for 2 days, then closing the power supply of the oven, naturally cooling the autoclave to room temperature, performing centrifugal separation on substances in the autoclave, cleaning the solids obtained by the centrifugal separation, and then placing the cleaned solids in a dry stateDrying at 60 deg.C for 4 hr in drying oven, and calcining at 400 deg.C for 1 hr in vacuum annealing furnace to obtain VO2(M)-CoFe2O4A composite material.
Example 2
VO (volatile organic compound)2(M)-CoFe2O4The preparation method of the composite material can comprise the following steps:
step a2, according to cobalt nitrate (Co (NO)3)2·6H2O) iron nitrate (Fe (NO)3)3·9H2Dissolving cobalt nitrate, ferric nitrate and polyethylene glycol in the same alcohol solvent according to the molar ratio of 1:2:10:600, and magnetically stirring for 30min to obtain a clear mixed solution; then, dropwise adding nitric acid into the stirred mixed solution until the pH value of the mixed solution is 1.5, thereby obtaining a cobalt ferrite reaction precursor; stirring the cobalt ferrite reaction precursor for 6 hours at 80 ℃ until sol is formed; allowing the sol to stand in air for several days until an orange gel is formed; the orange gel was dried at 60 ℃ for 4 hours to form a dry gel, and the dry gel was calcined at 700 ℃ for 2 hours and ground to a powder to produce CoFe2O4And (3) powder.
Step b2 according to CoFe2O4Vanadium pentoxide (V)2O5) Hydrogen peroxide (H)2O2) Polyvinylpyrrolidone (PVP) deionized water at a molar ratio of 1:0.5:0.1:1:50, CoFe2O4Dissolving the powder, vanadium pentoxide, hydrogen peroxide and polyvinylpyrrolidone into deionized water, and carrying out ultrasonic treatment for 30min to mix the materials together, thereby obtaining a reaction precursor solution.
Step c2, placing the reaction precursor solution in an autoclave with a polytetrafluoroethylene inner container, screwing the autoclave tightly, placing the autoclave in an oven, heating the autoclave from room temperature to 220 ℃, preserving the heat for 2 days, then closing the power supply of the oven, naturally cooling the autoclave to room temperature, carrying out centrifugal separation on substances in the autoclave, cleaning the solids obtained by the centrifugal separation, and then placing the cleaned solids in the oven at 60 DEG CDrying for 4 hours, and calcining for 1 hour at 400 ℃ in a vacuum annealing furnace to prepare the VO2(M)-CoFe2O4A composite material.
Morphology and Performance detection
The following morphology and performance tests were performed on comparative example 1 and inventive examples 1-2, respectively:
(1) VO in comparative example 1 was subjected to X-ray diffraction (XRD) measurement2(M) nanopowder and VO in examples 1 to 2 of the present invention2(M)-CoFe2O4The composite was examined to obtain an X-ray diffraction pattern as shown in figure 1. Wherein, the ordinate in fig. 1 is relative intensity, and the abscissa is diffraction angle; curve (1) in FIG. 1 represents VO in comparative example 1 described above2(M) nanopowders (i.e., without CoFe addition)2O4) Curve (2) in fig. 1 represents VO in example 1 of the present invention2(M)-CoFe2O4Composite materials (i.e. CoFe)2O4And V2O5Composite material obtained at a molar ratio of 1: 2), and curve (3) in fig. 1 represents VO in example 2 of the present invention2(M)-CoFe2O4Composite materials (i.e. CoFe)2O4And V2O5The molar ratio of (1) to (2) of the obtained composite material. As can be seen from fig. 1: comparative example 1 with no CoFe addition2O4All diffraction peaks of the finally prepared product can be calibrated to be monoclinic phase VO2And can be well matched with the data reported by JCPDS card (No.44-0252), and no diffraction characteristic peak of other impurities is found; in example 1 of the present invention, CoFe2O4And V2O5At a molar ratio of 1:2, and CoFe in example 2 of the present invention2O4And V2O5The molar ratio of (1) to (2) can calibrate CoFe for all diffraction peaks of the finally prepared product2O4And VO2A complex and wherein VO2Is a monoclinic phase, the diffraction peak of which can be well matched with the data reported by JCPDS card (No.44-0252), CoFe2O4Has a spinel structure, and the diffraction peak of the spinel structure can be well matched with the data reported by JCPDS cards (No. 22-1086); further comparison shows that: with CoFe2O4Increase in the content, VO2(M)-CoFe2O4The intensity of the diffraction peak of the composite material decreases.
(2) VO in comparative example 1 was individually subjected to a field emission scanning electron microscope of Sirion 200 type in the United states2(M) nanopowder and VO in inventive example 12(M)-CoFe2O4The composite material was examined to obtain a scanning electron micrograph (FESEM image) as shown in fig. 2. Wherein FIG. 2(a) is VO in comparative example 1 described above2(M) nanopowders (i.e., without CoFe addition)2O4) Scanning Electron micrograph (FESEM image) of (1), FIG. 2(b) is VO in example 1 of the present invention2(M)-CoFe2O4Composite materials (i.e. CoFe)2O4And V2O5Composite material prepared at a molar ratio of 1: 2) was obtained. As can be seen from fig. 2: VO in example 1 of the present invention2(M)-CoFe2O4The majority of the composite material is spherical or spherical-like nano particles, and the yield is high; with CoFe2O4Increased content of VO2(M)-CoFe2O4The particle size of the composite material tends to decrease slightly.
(3) VO in the above comparative example 1 was subjected to differential scanning calorimeter (Netzsch DSC-4000)2(M) nanopowder and VO in examples 1 to 2 of the present invention2(M)-CoFe2O4The composite material is detected under the protection of high-purity nitrogen, so that a DSC curve comparison graph shown in figure 3 is obtained. Wherein the abscissa in fig. 3 is temperature and the ordinate is heat; curve (1) in FIG. 3 represents VO in comparative example 1 described above2(M) nanopowders (i.e., without CoFe addition)2O4) Curve (2) in fig. 3 represents VO in example 1 of the present invention2(M)-CoFe2O4Composite materials (i.e. CoFe)2O4And V2O5In a molar ratio of1: 2) and curve (3) in FIG. 3 represents VO in example 2 of the present invention2(M)-CoFe2O4Composite materials (i.e. CoFe)2O4And V2O5A 2:1 molar ratio) of the obtained composite material). As can be seen from fig. 3: with the rise of the temperature, an obvious endothermic peak appears, and the temperature corresponding to the endothermic peak is VO2A phase transition temperature of (M); during the temperature rise, CoFe is not added2O4Pure VO of2The phase transition temperature of (M) is 76.7 ℃ with CoFe2O4Increased content of VO2(M)-CoFe2O4The phase transition temperature of the composite material gradually decreases.
In conclusion, the embodiment of the invention has the advantages of simple preparation method, low cost, adjustable components and easy realization of large-scale production, can reduce the phase transition temperature, and can greatly improve the visible light transmittance under the condition of not remarkably reducing the solar energy regulation amplitude, thereby realizing lower phase transition temperature and simultaneously obtaining the visible light transmittance higher than 40% and the solar energy regulation amplitude larger than 10%.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are 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. VO (volatile organic compound)2(M)-CoFe2O4The composite material is characterized in that the composition of the composite material comprises monoclinic phase VO2And CoFe of spinel structure2O4And the monoclinic phase VO2And CoFe of the spinel structure2O4All are nanospheres with a particle size of 30-90 nm.
2. VO according to claim 12(M)-CoFe2O4Composite material, characterized in that the monoclinic phase VO2And CoFe of the spinel structure2O4Are all nanospheres with an average particle size of 70 nm.
3. VO according to claim 1 or 22(M)-CoFe2O4Composite material, characterized in that the monoclinic phase VO2And CoFe of the spinel structure2O4The molar ratio of (A) to (B) is 1-0.1: 0.01-1.
4. VO (volatile organic compound)2(M)-CoFe2O4The preparation method of the composite material is characterized by comprising the following steps:
step A, according to CoFe2O4Vanadium pentoxide, hydrogen peroxide, polyvinylpyrrolidone and deionized water in a molar ratio of 0.01-1: 1-0.1: 0.02-0.4: 0.2-1: 30-100, and adding CoFe2O4Dissolving vanadium pentoxide, hydrogen peroxide and polyvinylpyrrolidone into deionized water, and mixing together to obtain a reaction precursor solution;
step B, placing the reaction precursor solution into an autoclave with a polytetrafluoroethylene inner container, placing the autoclave in an oven, heating the autoclave from room temperature to 180-250 ℃, preserving heat for 1-4 days, cooling the autoclave to room temperature, performing solid-liquid separation on substances in the autoclave, sequentially performing cleaning treatment and drying treatment on solids obtained by the solid-liquid separation, placing the autoclave in a vacuum annealing furnace for calcination at 250-500 ℃ for 1-2 hours, and thus obtaining the VO of any one of claims 1-32(M)-CoFe2O4A composite material.
5. VO according to claim 42(M)-CoFe2O4A method for producing a composite material, characterized in that the CoFe2O4The preparation method comprises the following steps: dissolving cobalt nitrate, ferric nitrate and polyethylene glycol into wine according to the molar ratio of cobalt nitrate, ferric nitrate, polyethylene glycol and alcohol of 0.2-1: 0.4-2: 0.2-10: 200-1000Performing magnetic stirring in the refined solvent, and then dropwise adding nitric acid into the stirred mixed solution until the pH value of the mixed solution is 1.5-2, so as to obtain a cobalt ferrite reaction precursor; stirring the cobalt ferrite reaction precursor at 60-120 ℃ until sol is formed; placing the sol in air until an orange gel is formed; drying the orange gel to form dry gel, calcining the dry gel at 400-900 ℃ for 2 hours, and grinding the dry gel into powder to obtain CoFe2O4And (3) powder.
6. VO according to claim 52(M)-CoFe2O4The preparation method of the composite material is characterized in that the stirring speed of the magnetic stirring is 100-300 rpm/min, and the stirring time is 10-30 min.
7. VO according to claim 4 or 5 or 62(M)-CoFe2O4The preparation method of the composite material is characterized in that the solid-liquid separation is centrifugal separation, the rotating speed of the centrifugal separation is 7000-10000 r/min, and the centrifugal separation time is 3-10 min.
8. VO according to claim 4 or 5 or 62(M)-CoFe2O4The preparation method of the composite material is characterized in that the cleaning treatment is to alternately clean the solid obtained by solid-liquid separation for 7-9 times by using deionized water and ethanol or distilled water and ethanol.
9. VO according to claim 4 or 5 or 62(M)-CoFe2O4The preparation method of the composite material is characterized in that the drying treatment is to heat the cleaned solid object at 50-80 ℃ for 3-4 hours.
10. VO (volatile organic compound)2(M)-CoFe2O4Use of a composite material of VO according to any of the preceding claims 1 to 3, characterised in that2(M)-CoFe2O4Composite materials are used for "smart windows".
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