CN112023929B

CN112023929B - Preparation method and application of transition metal double hydroxide nano-film and carbon nano-tube composite material

Info

Publication number: CN112023929B
Application number: CN201911159603.5A
Authority: CN
Inventors: 邓意达; 赵君; 王杨; 胡文彬; 张金凤; 韩晓鹏; 钟澄; 邱留喆
Original assignee: Tianjin University
Current assignee: Tianjin University
Priority date: 2019-11-22
Filing date: 2019-11-22
Publication date: 2021-12-03
Anticipated expiration: 2039-11-22
Also published as: CN112023929A

Abstract

The invention discloses a preparation method and application of a transition metal double hydroxide nano film and carbon nano tube composite material, wherein metal salt is weighed, dissolved in saturated oxygen deionized water, uniformly stirred in an oxygen atmosphere, added with carbon nano tubes, continuously stirred uniformly and dispersed, then added with alkali solution, adjusted to increase oxygen gas flow and stirred to obtain a precipitate; and centrifugally cleaning the precipitate by using deionized water and absolute ethyl alcohol, and drying by using a vacuum oven to obtain the nano-scale powder material. The preparation method is simple, is easy and convenient to operate, has low cost and has good industrial application prospect.

Description

Preparation method and application of transition metal double hydroxide nano-film and carbon nano-tube composite material

Technical Field

The invention relates to a preparation method and application of a nano catalytic material in the field of electrocatalysis, in particular to a preparation method and application of a transition metal double hydroxide nano film and carbon nano tube composite material.

Background

Layered metal hydroxides (LDHs) have good application prospects in the fields of energy conversion and energy storage such as electrocatalysis, secondary batteries, super capacitors and the like. The crystal structure is layered, has the lowest lattice energy and lattice positioning effect, and consists of metal hydroxide, the main layer is metal cation, the transition layer is hydroxyl ion, and is easy to adsorb other anions, the components are easy to adjust, and the crystal structure can be compounded with other materials to realize functionalization. The LDHs can provide a large surface area for catalytic reaction as a catalytic material, metal ions are considered as hydroxide electrocatalytic active centers, different single metals have different catalytic reaction activities, and compared with single metal hydroxides, the bimetallic layered double hydroxide can provide two metal active centers which are mutually synergistic for catalytic reaction, so that the layered double hydroxide is considered as an ideal catalytic material.

The LDHs is used for catalyzing oxygen precipitation materials, and has the main defects of layered stacking, insufficient exposure of active sites, relatively poor conductivity and slow electron transmission rate, so that the prepared single-layer or few-layer LDHs is compounded with a high-conductivity material to realize high active site exposure and accelerate electron transmission, and is a promising catalytic material. The carbon nano tube has excellent electronic conduction performance due to the special graphite layer structure, and the formed three-dimensional network structure is beneficial to fully contacting with the LDHs and supporting the LDHs to extend and grow, so that the exposure of surface active sites is improved, the electrical conductivity and the catalytic activity of the material can be improved, the agglomeration of the LDHs in the catalytic process can be avoided, and the structural stability is maintained. The preparation method of the few-layer layered double hydroxide mainly comprises the following steps: hydrothermal method, electrodeposition method and stripping of thick layer of double hydroxide. Wherein the hydrothermal method has a longer preparation period, and the material is easy to agglomerate in a high-temperature and high-pressure preparation environment. The electrodeposition operation is simple, heating and pressurizing are not needed, the experimental conditions are simple, the production period is short, but the electrodeposition method is difficult to obtain few-layer LDHs and cannot realize mass production. The liquid phase method has short synthesis period and high yield, but the prepared LDHs layer sheet is thicker, and if the method is combined with stripping to prepare few layers of LDHs in one step, the short-period and large-scale production can be realized.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provides a preparation method and application of a transition metal double hydroxide nano film and carbon nano tube composite material. According to the technical scheme, oxygen flows in on the basis of a liquid phase method, the layered structure is stripped through oxygen molecules, the thin-layer LDHs is prepared, the method is simple, the prepared transition metal double hydroxide is a graphene-like film nanometer material, the contact area in the electrocatalytic reaction is increased, and the electrical conductivity of the material can be increased by compounding the transition metal double hydroxide with the carbon nano tube. The method can realize high-yield preparation, and has excellent energy storage and conversion application prospects.

The technical purpose of the invention is realized by the following technical scheme.

A preparation method of a transition metal double hydroxide nano-film and carbon nano-tube composite material comprises the following steps:

step 1, weighing two transition metal salts for forming transition metal double hydroxide, dissolving the two transition metal salts in deionized water with saturated oxygen, and stirring and dissolving the two transition metal salts in an oxygen protective atmosphere to form a transparent solution;

step 2, adding the carbon nano tube into the transparent solution obtained in the step 1, and continuously stirring in an oxygen protective atmosphere to form a uniform suspension;

step 3, quickly pouring the alkali solution into the suspension obtained in the step 2, and stirring in an oxygen protective atmosphere to obtain a precipitate;

and 4, washing the precipitate obtained in the step 3 with deionized water and absolute ethyl alcohol in sequence, and drying in a vacuum oven to obtain the transition metal double hydroxide nano film and carbon nano tube composite material.

In step 1, the transition metal salt is cobalt salt, nickel salt, vanadium salt and manganese salt, the cobalt salt is cobalt nitrate, cobalt chloride and cobalt acetate, the nickel salt is nickel nitrate, nickel chloride and nickel acetate, the vanadium salt is vanadium chloride, and the manganese salt is manganese nitrate and manganese acetate.

In the step 1, the total amount of the two transition metals is 3-15 mmol, and the two transition metals are selected from cobalt vanadium (the molar ratio of Co: V is 3:1), cobalt manganese (the molar ratio of Co: Mn is 3:1), cobalt nickel (the molar ratio of Co: Ni is 4:1), nickel vanadium (the molar ratio of Ni: V is 3:1) and nickel manganese (the molar ratio of Ni: Mn is 3: 1).

In the step 1, the flow rate of oxygen is 70-100 mL/min, the stirring speed is 400-500 r/min, and the stirring time is 20-40 min; the flow rate of the oxygen is 80-100 mL/min, the stirring rate is 420-460 r/min, and the stirring time is 20-30 min.

In the step 2, the addition amount of the carbon nano tube is 0.1-0.6 mg; the mass ratio of the sum of the two transition metal salts in the step 1 to the carbon nano tube is (20-45): 1.

in the step 2, the mass sum of transition metal cobalt vanadium, cobalt nitrate and vanadium chloride is selected as follows: the mass ratio of the carbon nano tube is 41.2: 1; selecting the mass sum of transition metal cobalt manganese, cobalt nitrate and manganese acetate: the mass ratio of the carbon nano tube is 43.6: 1; selecting the mass sum of transition metals of cobalt nickel, cobalt nitrate and nickel nitrate: the mass ratio of the carbon nano tube is 21.8: 1; selecting the mass sum of transition metal nickel vanadium, nickel nitrate and vanadium chloride: the mass ratio of the carbon nano tubes is 27.5: 1; selecting the mass sum of transition metal nickel manganese, nickel nitrate and manganese acetate: the ratio of the mass of the carbon nanotubes was 42.3: 1.

In the step 2, the flow rate of the oxygen is 70-100 mL/min, the stirring speed is 400-500 r/min, and the stirring time is 20-40 min; the flow rate of the oxygen is 80-100 mL/min, the stirring rate is 420-460 r/min, and the stirring time is 20-30 min.

In the step 3, the alkali liquor is sodium hydroxide or potassium hydroxide aqueous solution, the concentration is 1-5 mol/L, and the whole reaction system is in an alkaline environment (such as 8-12) after the alkali liquor is added; the flow rate of the oxygen gas is 100-150 mL/min; the stirring speed is 400-500 r/min, the stirring time is 20-150 min, and the preferred oxygen flow is 120-150 mL/min; the stirring speed is 420-460 r/min, and the stirring time is 50-120 min.

In the step 4, the vacuum drying temperature is 25-60 ℃, the vacuum drying time is 10-20 hours, the preferred vacuum drying temperature is 30-50 ℃, and the vacuum drying time is 15-20 hours.

The preparation method of the transition metal double hydroxide nano film and carbon nano tube composite material is applied to the preparation of the transition metal double hydroxide nano film, the thickness of the transition metal double hydroxide nano film is less than 10 nanometers, and the preferable thickness is 3-8 nm; the transition metal double hydroxide nano-film and the carbon nano-tube composite material obtained by the preparation method are applied to electrocatalytic materials.

In the technical scheme of the invention, different from the traditional experimental method in which the introduction of inert protective gas (such as nitrogen, helium and argon) is selected, a liquid phase method for introducing oxygen to strip the layered structure is selected, and in the synthesis process, the continuously supplied oxygen molecules and the continuously stirred experimental environment can realize the stripping of the layered double hydroxide crystal structure, so that the thickness of the material is greatly reduced, and the composite material of the thin film LDHs and the carbon nano tube with stable structure is prepared in one step. The mechanism of the preparation method for simultaneously carrying out precipitation and stripping is as follows: during the stirring process, oxygen molecules can enter into main LDHs layers to promote the interlayer separation and absorb hydroxyl, so that a few-layer structure is formed, the generation of double hydroxide is facilitated, and the nano-scale (such as below 10 nm) is achieved. The method is used for successfully preparing the cobalt-vanadium, cobalt-manganese, cobalt-nickel, nickel-vanadium and nickel-manganese few-layer double metal hydroxide composite carbon fiber material, is applied to electrocatalytic oxygen precipitation, and has good catalytic performance. Compared with the prior art, the invention has the following beneficial effects:

(1) the preparation method of the invention has the advantages of simple equipment conditions, convenient operation and low preparation cost, and is suitable for industrial large-scale production.

(2) The method adopts a one-step liquid phase method to prepare the composite material of the transition metal double hydroxide nanometer film and the carbon nanometer tube by simultaneously flowing oxygen in parallel, has high repeatability, can effectively ensure the shape control of the product, and greatly simplifies the preparation process flow. The prepared composite material of the transition metal double hydroxide nano film and the carbon nano tube has good electrocatalytic oxygen precipitation, hydrogen precipitation and oxygen reduction performances, can be used for the catalysis of working electrodes of electrolytic water and air batteries, and has excellent cycle stability.

Drawings

FIG. 1 is an X-ray diffraction diagram of the cobalt vanadium double hydroxide and carbon nanotube composite material prepared by the method.

FIG. 2 is an X-ray diffraction diagram of the cobalt-manganese double hydroxide and carbon nanotube composite material prepared by the method.

FIG. 3 is an X-ray diffraction diagram of the cobalt-nickel double hydroxide and carbon nanotube composite material prepared by the method.

FIG. 4 is an X-ray diffraction diagram of the composite material of nickel vanadium double hydroxide and carbon nano tube prepared by the method.

FIG. 5 is an X-ray diffraction pattern of the composite material of nickel-manganese double hydroxide and carbon nanotube prepared by the method.

FIG. 6 is a scanning electron microscope photograph of the cobalt vanadium double hydroxide and carbon nanotube composite material prepared by the method.

FIG. 7 is a scanning electron microscope photograph of the composite material of cobalt manganese double hydroxide and carbon nanotube prepared by the method.

FIG. 8 is a scanning electron microscope photograph of the composite material of cobalt-nickel double hydroxide and carbon nanotube prepared by the method.

FIG. 9 is a scanning electron microscope photograph of the composite material of nickel vanadium double hydroxide and carbon nanotube prepared by the method.

FIG. 10 is a scanning electron microscope photograph of the composite material of nickel manganese double hydroxide and carbon nanotube prepared by the method.

FIG. 11 is an atomic force microscope image test result diagram of the cobalt vanadium double hydroxide obtained in the technical scheme of the method.

FIG. 12 is a line-scanning curve diagram of electrocatalytic oxidation of the transition metal double hydroxide and carbon nanotube composite material prepared by the method.

FIG. 13 is a schematic diagram of the steps of the present invention.

Detailed Description

The technical solution of the present invention will be described in detail with reference to specific examples.

Example 1

(1) 3.49g of cobalt nitrate and 0.63g of vanadium chloride are weighed and dissolved in 50mL of deionized water with saturated oxygen, and the mixture is stirred and dissolved in an oxygen protective atmosphere, wherein the oxygen gas flow is 70mL/min, so that a transparent solution is formed.

(2) 0.1g of carbon nano tube is added into the transparent solution, and stirring is continued for 30 minutes under the condition of oxygen introduction, so as to obtain uniform suspension.

(3) And (3) rapidly adding 25mL of 2mol/L sodium hydroxide into the suspension, adjusting the flow rate of the atmospheric oxygen to be 80mL/min, stirring at the rotation speed of 500r/min for 30min, and obtaining brown precipitate.

(4) And sequentially washing the brown precipitate with deionized water and absolute ethyl alcohol for three times respectively, and drying in a vacuum oven at 30 ℃ for 15 hours to obtain the composite material of the nano-film cobalt-vanadium double hydroxide and the carbon nano tube.

FIG. 1 is an X-ray diffraction pattern of the composite material of cobalt vanadium double hydroxide and carbon nanotube prepared in this example, from which it can be seen that the prepared material has very good hydrotalcite structure characteristic peak, and the main phase crystal structure corresponds to a-Co (OH)₂And in addition, the vanadium element is contained, and the atomic content ratio of Co to V is 5.6 to 1 in a spectrum test.

FIG. 6 is a scanning electron micrograph of the material prepared in this example, which shows that the cobalt vanadium double hydroxide is in the form of a thin film, and is uniformly attached and dispersed on the carbon nanotubes.

FIG. 11 is an atomic force microscope picture and a corresponding position thickness analysis picture of the cobalt vanadium double hydroxide and carbon nanotube composite material prepared by the method, a sample with visible flesh eyes is taken and put into a test tube, high-purity alcohol is added for ultrasonic treatment, the ultrasonic treatment time is 1 hour, 10 microliter of dispersion liquid is dripped onto a clean mica sheet, the mica sheet is shaken to enable the dispersion liquid to be uniformly dispersed on the whole mica sheet, and the mica sheet is naturally dried. The adopted atomic force electron microscope testing instrument is Agilent afm5500, the thickness of the cobalt vanadium double hydroxide is about 3nm, and the thickness of the carbon nano tube tested under the same condition is about 4nm indicates the O introduced during the preparation₂Good stripping effect is generated on the cobalt-vanadium double hydroxide.

Dispersing the product in a solution of absolute ethyl alcohol and Nafion binder in a volume ratio of 97:3, uniformly mixing by ultrasonic, coating the mixed slurry on foamed nickel, and placing the foamed nickel in an air drying box with a temperature of 50 ℃ for drying treatment. Finally, electrochemical performance tests were carried out, and oxygen evolution at 60mA/cm is shown in FIG. 12²The overpotential was 370mV under current. The electrochemical oxygen evolution test adopts a three-electrode system test, the foamed nickel coated with the catalyst slurry (namely the composite material prepared by the invention) is used as a working electrode, the calomel electrode is used as a reference electrode, and the graphite carbon rod is used as an auxiliary electrode. The electrolyte is 1.0mol/L KOH aqueous solution, the test is carried out under the condition of room temperature, and an electrochemical workstation is a Netherlands Ivium electrochemical workstation.

Example 2

(1) 3.49g of cobalt nitrate and 0.74g of manganese acetate are weighed and dissolved in 50mL of deionized water with saturated oxygen, and the mixture is stirred and dissolved in an oxygen protective atmosphere, wherein the oxygen gas flow is 70mL/min, so that a transparent solution is formed.

(2) 0.08g of carbon nanotubes was added to the above solution, and stirring was continued for 30 minutes under oxygen-introduced conditions.

(3) And (3) rapidly adding 20mL of 2mol/L sodium hydroxide into the mixed suspension, adjusting the flow rate of the atmospheric oxygen to be 80mL/min, stirring at the rotation speed of 500r/min for 1.5h, and obtaining a dark brown precipitate.

(4) And sequentially washing the brown precipitate with deionized water and absolute ethyl alcohol for three times respectively, and drying in a vacuum oven at 30 ℃ for 15 hours to obtain the composite material of the nano-film cobalt-manganese double hydroxide and the carbon nano tube, wherein the phase and the appearance are shown in figures 2 and 7.

Fig. 2 is an X-ray diffraction pattern of the composite material of cobalt manganese double hydroxide and carbon nanotube prepared in this example, and it can be seen from the pattern that the crystal structure of the main phase of the prepared material corresponds to coo (oh), and the material further contains manganese element, and the atomic content ratio in the energy spectrum test is Co: Mn: 5.7: 1.

FIG. 7 is a scanning electron micrograph of the material prepared in this example, which can be seenThe cobalt-manganese double hydroxide is in a film shape and is uniformly attached and dispersed on the carbon nano tube. Placing a sample visible to the naked eye into a test tube, adding high-purity alcohol for ultrasonic treatment for 1 hour, dripping 10 microliters of dispersion liquid onto a clean mica sheet, shaking the mica sheet to uniformly disperse the dispersion liquid on the whole mica sheet, and naturally drying. The adopted atomic force electron microscope tester is Agilent afm5500, the thickness of the cobalt manganese hydroxide in the cobalt manganese hydroxide and carbon nano tube composite material is about 3nm, the thickness of the carbon nano tube is about 4nm, and the instruction shows that O is introduced in the preparation process₂Good stripping effect is generated on the cobalt-vanadium double hydroxide.

Dispersing the product in a solution of absolute ethyl alcohol and Nafion binder in a volume ratio of 97:3, uniformly mixing by ultrasonic, coating the mixed slurry on foamed nickel, and placing the foamed nickel in an air drying box with a temperature of 50 ℃ for drying treatment. Finally, electrochemical performance tests were carried out, and oxygen evolution at 60mA/cm is shown in FIG. 12²The overpotential was 520mV at current.

Example 3

(1) 3.49g of cobalt nitrate and 0.87g of nickel nitrate are weighed and dissolved in 50mL of deionized water with saturated oxygen, and the mixture is stirred and dissolved in an oxygen protective atmosphere, wherein the oxygen gas flow is 70mL/min, so that a transparent solution is formed.

(2) 0.2g of carbon nanotubes was added to the above solution, and stirring was continued for 60 minutes under oxygen-introduced conditions.

(3) And (3) rapidly adding 20mL of 2mol/L sodium hydroxide into the mixed suspension, adjusting the flow rate of the oxygen to be 100mL/min, stirring at the rotation speed of 600r/min for 0.5h, and obtaining dark green precipitate.

(4) And sequentially washing the dark green precipitate with deionized water and absolute ethyl alcohol for three times respectively, and drying in a vacuum oven at 35 ℃ for 20 hours to obtain the composite material of the nano-film cobalt-nickel double hydroxide and the carbon nano tube, wherein the phase and the appearance are shown in figures 3 and 8.

FIG. 3 is an X-ray diffraction pattern of the composite material of Co-Ni double hydroxide and carbon nanotube, which shows that the crystal structure of the main phase of the prepared material is Co (OH)₂In addition, anotherThe alloy contains nickel element, and the atomic content ratio of Co to Ni is 3.7 to 1 in the energy spectrum test. FIG. 8 is a scanning electron micrograph of the material prepared in this example, which shows that the cobalt-nickel double hydroxide is in the form of a thin film, and is uniformly attached and dispersed on the carbon nanotubes. Placing a sample visible to the naked eye into a test tube, adding high-purity alcohol for ultrasonic treatment for 1 hour, dripping 10 microliters of dispersion liquid onto a clean mica sheet, shaking the mica sheet to uniformly disperse the dispersion liquid on the whole mica sheet, and naturally drying. The adopted atomic force electron microscope tester is Agilent afm5500, the thickness of the cobalt nickel hydroxide in the cobalt nickel hydroxide and carbon nano tube composite material is about 5nm, the thickness of the carbon nano tube is about 4nm, and the O introduced in the preparation process is proved₂Good stripping effect is generated on the cobalt-nickel double hydroxide.

Dispersing the product in a solution of absolute ethyl alcohol and Nafion binder in a volume ratio of 97:3, uniformly mixing by ultrasonic, coating the mixed slurry on foamed nickel, placing the foamed nickel in an air drying box with a temperature of 50 ℃ for drying treatment, dripping the mixed slurry on a rotating disc ring electrode, and drying at room temperature. Finally, electrochemical performance tests were carried out, and as shown in FIG. 12, oxygen evolution was at 60mA/cm²The overpotential was 430mV at current.

Example 4

(1) 3.49g of nickel nitrate and 0.63g of vanadium chloride are weighed and dissolved in 45mL of deionized water with saturated oxygen, and the mixture is stirred and dissolved in an oxygen protective atmosphere, wherein the flow rate of oxygen gas is 70mL/min, so that a transparent solution is formed.

(2) 0.15g of carbon nanotubes was added to the above solution, and stirring was continued for 35 minutes under oxygen-introduced conditions.

(3) And (3) rapidly adding 20mL of 2mol/L sodium hydroxide into the mixed suspension, adjusting the flow rate of the oxygen to be 90mL/min, stirring at the rotating speed of 600r/min for 1h, and obtaining dark green precipitate.

(4) And sequentially washing the brown precipitate with deionized water and absolute ethyl alcohol for three times respectively, and drying in a vacuum oven at 30 ℃ for 16 hours to obtain the composite material of the nano-film nickel-vanadium double hydroxide and the carbon nano tube, wherein the phase and the appearance are shown in figures 4 and 9.

FIG. 4 is an X-ray diffraction pattern of the composite material of Ni-V double hydroxide and carbon nanotube, and it can be seen from the figure that the crystal structure of the main phase of the prepared material corresponds to Ni (OH)₂And the alloy also contains vanadium, and the atomic content ratio of Ni to V is 6.3 to 1 in a spectrum test. FIG. 9 is a scanning electron micrograph of the material prepared in this example, which shows that the Ni-V double hydroxide is in the form of a thin film, and is uniformly attached and dispersed on the carbon nanotubes. Placing a sample visible to the naked eye into a test tube, adding high-purity alcohol for ultrasonic treatment for 1 hour, dripping 10 microliters of dispersion liquid onto a clean mica sheet, shaking the mica sheet to uniformly disperse the dispersion liquid on the whole mica sheet, and naturally drying. The atomic force electron microscope testing instrument adopted is Agilent afm5500, the thickness of the nickel vanadium hydroxide in the nickel vanadium hydroxide and carbon nano tube composite material is about 8nm, the thickness of the carbon nano tube is about 4nm, and the O introduced in the preparation process is proved₂Good stripping effect is generated on the nickel-vanadium double hydroxide.

Dispersing the product in a solution of absolute ethyl alcohol and Nafion binder in a volume ratio of 97:3, uniformly mixing by ultrasonic, coating the mixed slurry on foamed nickel, and placing the foamed nickel in an air drying box with a temperature of 50 ℃ for drying treatment. Finally, electrochemical performance tests were carried out, and oxygen evolution at 60mA/cm is shown in FIG. 12²The overpotential was 410mV at current.

Example 5

(1) 3.49g of nickel nitrate and 0.74g of manganese acetate are weighed and dissolved in 50mL of deionized water with saturated oxygen, and the mixture is stirred and dissolved in an oxygen protective atmosphere, wherein the oxygen gas flow is 90mL/min, so that a transparent solution is formed.

(2) 0.1g of carbon nanotubes was added to the above solution, and stirring was continued for 40 minutes under oxygen-introduced conditions.

(3) And (3) rapidly adding 25mL of 1.6mol/L sodium hydroxide into the mixed suspension, adjusting the flow rate of the oxygen gas to be 100mL/min, stirring at the rotating speed of 600r/min for 2h, and obtaining a dark brown precipitate.

(4) And sequentially washing the brown precipitate with deionized water and absolute ethyl alcohol for three times respectively, and drying in a vacuum oven at 35 ℃ for 14 hours to obtain the composite material of the nano-film cobalt-manganese double hydroxide and the carbon nano tube, wherein the phase and the appearance are shown in figures 5 and 10.

FIG. 5 is an X-ray diffraction pattern of the composite material of Ni-Mn double hydroxide and carbon nanotube, which shows that the main phase crystal structure of the prepared material is Ni (OH)₂And the alloy also contains manganese element, and the atomic content ratio of Ni to Mn is 4.2:1 by a spectrum test. FIG. 10 is a scanning electron micrograph of the material prepared in this example, which shows that the nickel manganese double hydroxide is in the form of a thin film, and is uniformly attached and dispersed on the carbon nanotubes. Placing a sample visible to the naked eye into a test tube, adding high-purity alcohol for ultrasonic treatment for 1 hour, dripping 10 microliters of dispersion liquid onto a clean mica sheet, shaking the mica sheet to uniformly disperse the dispersion liquid on the whole mica sheet, and naturally drying. The adopted atomic force electron microscope testing instrument is Agilent afm5500, the thickness of the nickel-manganese hydroxide in the nickel-manganese hydroxide and carbon nano tube composite material is about 5nm, the thickness of the carbon nano tube is about 4nm, and the O introduced in the preparation process is proved₂Good stripping effect is generated on the nickel-manganese double hydroxide.

Dispersing the product in a solution of absolute ethyl alcohol and Nafion binder in a volume ratio of 97:3, uniformly mixing by ultrasonic, coating the mixed slurry on foamed nickel, and placing the foamed nickel in an air drying box with a temperature of 50 ℃ for drying treatment. Finally, electrochemical performance tests were carried out, and oxygen evolution at 60mA/cm is shown in FIG. 12²The overpotential was 420mV at current.

The preparation of the composite material can be realized by adjusting the process parameters according to the content of the invention, and the composite material shows the performance basically consistent with the invention through tests. The invention has been described in an illustrative manner, and it is to be understood that any simple variations, modifications or other equivalent changes which can be made by one skilled in the art without departing from the spirit of the invention fall within the scope of the invention.

Claims

1. a preparation method for the transition metal double hydroxide nano-film for electrocatalysis and carbon nanotube composite material, is characterized in that, carry out according to the following steps:

Step 1: Weigh the two transition metal salts that form the transition metal double hydroxide, dissolve them in deionized water with saturated oxygen, stir and dissolve in an oxygen protective atmosphere, and form a transparent solution; the transition metal salts are cobalt salts, nickel salts , vanadium salt or manganese salt, cobalt salt is cobalt nitrate, cobalt chloride or cobalt acetate, nickel salt is nickel nitrate, nickel chloride or nickel acetate, vanadium salt is vanadium chloride, manganese salt is manganese nitrate or manganese acetate; oxygen The flow rate is 70～100mL/min, the stirring rate is 400～500r/min, and the stirring time is 20～40min;

In step 2, carbon nanotubes are added to the transparent solution obtained in step 1, and in an oxygen protective atmosphere, stirring is continued to form a uniform suspension; the ratio of the sum of the mass of the two transition metal salts in step 1 to the mass of carbon nanotubes is: (20-45): 1; the oxygen flow rate is 70-100mL/min, the stirring rate is 400-500r/min, and the stirring time is 20-40min;

In step 3, the alkaline solution is quickly poured into the suspension obtained in step 2, and stirred in an oxygen protective atmosphere to obtain a precipitate; the alkaline solution is an aqueous solution of sodium hydroxide or potassium hydroxide, and the entire reaction system is alkaline after adding. environment; the oxygen gas flow rate is 100-150mL/min; the stirring rate is 400-500r/min, and the stirring time is 20-150min;

In step 4, the precipitate obtained in step 3 is sequentially washed with deionized water and absolute ethanol, and dried in a vacuum oven to obtain a composite material of transition metal double hydroxide nano-film and carbon nanotube; the vacuum drying temperature is 25-60° C. , the vacuum drying time is 10 ~ 20h.

2. the preparation method of a kind of transition metal double hydroxide nano film for electrocatalysis and carbon nanotube composite material according to claim 1, is characterized in that, in step 1, two kinds of transition metal total amount are 3～15mmol, two transition metals are selected as cobalt vanadium, wherein Co:V molar ratio is 3:1, cobalt-manganese, wherein Co:Mn molar ratio is 3:1, cobalt-nickel, wherein Co:Ni molar ratio is 4: 1. Nickel vanadium, wherein the molar ratio of Ni:V is 3:1 or nickel-manganese, wherein the molar ratio of Ni:Mn is 3:1.

3. a kind of preparation method of transition metal double hydroxide nano film and carbon nanotube composite material for electrocatalysis according to claim 1, is characterized in that, in step 1, oxygen flow rate is 80～100mL/ min, the stirring rate is 420～460r/min, and the stirring time is 20～30min.

4. the preparation method of a kind of transition metal double hydroxide nano film for electrocatalysis and carbon nanotube composite material according to claim 1, is characterized in that, in step 2, select transition metal cobalt vanadium, nitric acid The sum of the mass of cobalt and vanadium chloride: the mass ratio of carbon nanotubes is 41.2:1; the sum of the mass of transition metal cobalt manganese, cobalt nitrate and manganese acetate: the ratio of carbon nanotube mass is 43.6:1; the transition metal is selected The sum of the mass of cobalt nickel, cobalt nitrate and nickel nitrate: the mass ratio of carbon nanotubes is 21.8:1; the sum of the mass of transition metal nickel vanadium, nickel nitrate and vanadium chloride: the mass ratio of carbon nanotubes is 27.5: 1; Select the transition metal nickel-manganese, the sum of the mass of nickel nitrate and manganese acetate: the ratio of the mass of carbon nanotubes is 42.3:1.

5. a kind of preparation method of transition metal double hydroxide nano film and carbon nanotube composite material for electrocatalysis according to claim 1, is characterized in that, in step 2, oxygen flow rate is 80～100mL/ min, the stirring rate is 420～460r/min, and the stirring time is 20～30min.

6. the preparation method of a kind of transition metal double hydroxide nano film and carbon nanotube composite material for electrocatalysis according to claim 1, is characterized in that, in step 3, described lye is hydroxide Sodium or potassium hydroxide aqueous solution, the concentration is 1-5 mol/L, the whole reaction system is alkaline environment pH is 8-12 after adding lye.

7. The preparation method of a transition metal double hydroxide nano-film for electrocatalysis and a carbon nanotube composite material according to claim 1, wherein in step 3, the oxygen gas flow is 120-150 mL /min; the stirring rate is 420-460 r/min, and the stirring time is 50-120 min.

8 . The method for preparing a transition metal double hydroxide nano-film for electrocatalysis and a carbon nanotube composite material according to claim 1 , wherein, in step 4, the vacuum drying temperature is 30-50 ℃. 9 . ℃, vacuum drying time is 15 ~ 20h.

9. a kind of transition metal double hydroxide nano film and carbon nano-film prepared by the preparation method of a transition metal double hydroxide nano film for electrocatalysis and carbon nanotube composite material as described in one of claims 1-8 The tube composite material is characterized in that the thickness of the transition metal double hydroxide nano film is less than 10 nanometers.

10 . The transition metal double hydroxide nano film and carbon nanotube composite material according to claim 9 , wherein the thickness of the transition metal double hydroxide nano film is 3-8 nm. 11 .

11. The application of the transition metal double hydroxide nanofilm and carbon nanotube composite material as claimed in claim 9 or 10 in an electrocatalytic material.