CN115995568A

CN115995568A - Carbon nano tube supported nickel-molybdenum alloy catalyst, preparation method and application thereof

Info

Publication number: CN115995568A
Application number: CN202310126426.0A
Authority: CN
Inventors: 高敏锐; 廖洁; 高飞跃; 杨宇; 王业华
Original assignee: University of Science and Technology of China USTC
Current assignee: University of Science and Technology of China USTC
Priority date: 2023-02-07
Filing date: 2023-02-07
Publication date: 2023-04-21

Abstract

The invention provides a preparation method of a carbon nano tube supported nickel-molybdenum alloy catalyst, which comprises the following steps: a) Treating the carbon nanotubes by using a Hummers method to obtain treated carbon nanotubes; b) Mixing the treated carbon nano tube, polyvinylpyrrolidone, nickel salt, molybdate, alcohol and water, then dropwise adding ammonia water, reacting for 10-30 min, and performing hydrothermal reaction; c) And drying the product of the hydrothermal reaction, and calcining at high temperature in a hydrogen-containing atmosphere to obtain the carbon nano tube supported nickel-molybdenum alloy catalyst. The invention also provides a carbon nano tube supported nickel-molybdenum alloy catalyst and application thereof.

Description

Carbon nano tube supported nickel-molybdenum alloy catalyst, preparation method and application thereof

Technical Field

The invention belongs to the technical field of electrocatalysis, and particularly relates to a carbon nano tube supported nickel-molybdenum alloy catalyst, a preparation method and application thereof.

Background

Finding new energy sources that are green and clean is one of the important ways to reduce carbon emissions. The hydrogen energy is an energy source with zero carbon emission, high heat value and wide sources, and can be directly converted into electric energy through the fuel cell. The development of fuel cells with high power density and good durability is an important way to efficiently utilize hydrogen energy.

Proton exchange membrane fuel cells have evolved into maturity over the last thirty years, but their price remains high. The cost of the noble metal platinum-based catalyst accounts for 20% of the total cost of the electric pile, and the marketability and the scale of the fuel cell are seriously restricted. Therefore, it is desirable to use non-noble metal-based catalysts that are earth-rich to drive down costs, but the problem of catalyst instability caused by the acidic environment of proton exchange membrane fuel cells makes this strategy difficult to advance. Moreover, the acidic environment severely corrodes bipolar plates of the galvanic pile, reducing safety. For this reason, anion exchange membrane fuel cells are increasingly coming into the field of research. The alkaline environment of the anion exchange membrane fuel cell is mild, and the anion exchange membrane fuel cell is suitable for using a non-noble metal catalyst. In an effort, hydrogen oxidation catalysts based on nickel-based materials have been reported frequently in recent years, and the activity of some materials has reached a higher level.

For example, wang Deli et al (Angew.chem.int.ed.2022, 61, e 202206588) calcine nickel hydroxide with an ammonia atmosphere at 300℃to obtain nickel nitride rich in nickel vacancies. Nickel vacancies promote the delocalization of the valence electrons in the OH adsorption center, resulting in enhanced OH adsorption; meanwhile, the H adsorption center valence electron is deleted, so that the H binding strength is weakened. Therefore, compared with nickel nitride with fewer nickel vacancies, the material has 15 times of alkaline hydrogen oxidation reaction mass activity.

However, the activity and stability of the nickel-based non-noble metal catalyst still have a large improvement space at present, and the application in the anion exchange membrane fuel cell is not fully studied and improved.

Disclosure of Invention

The invention aims to provide a carbon nano tube supported nickel-molybdenum alloy catalyst, a preparation method and application thereof.

The invention provides a preparation method of a carbon nano tube supported nickel-molybdenum alloy catalyst, which comprises the following steps:

a) Treating the carbon nanotubes by using a Hummers method to obtain treated carbon nanotubes;

b) Mixing the treated carbon nano tube, polyvinylpyrrolidone, nickel salt, molybdate, alcohol and water, then dropwise adding ammonia water, reacting for 10-30 min, and performing hydrothermal reaction;

c) And drying the product of the hydrothermal reaction, and calcining at high temperature in a hydrogen-containing atmosphere to obtain the carbon nano tube supported nickel-molybdenum alloy catalyst.

Preferably, the carbon nanotubes are treated using the Hummers method according to the following steps:

mixing the carbon nano tube with concentrated sulfuric acid, stirring for 5-15 hours, then sequentially adding sodium nitrate and potassium permanganate under the heating condition of 35-45 ℃, continuously stirring for 0.5-2 hours, slowly adding deionized water for dilution, then adding hydrogen peroxide solution, washing and freeze-drying to obtain the treated carbon nano tube.

Preferably, the carbon nanotubes are multi-walled carbon nanotubes, the inner diameter is 3-5 nm, the outer diameter is 8-15 nm, and the length is 45-55 μm.

Preferably, the volume ratio of water to alcohol is 1: (3-6); the mass ratio of the polyvinylpyrrolidone to the treated carbon nano tube is (11-17): 10.

preferably, the molar ratio of the nickel salt to the molybdate is (5-6): 1, a step of;

the mass ratio of the treated carbon nano tube to the nickel salt is 1: (3-12); the mass ratio of the treated carbon nano tube to the molybdate is 1: (0.3-1.2).

Preferably, the concentration of the ammonia water is 25-28%;

the ratio of the volume of ammonia water to the amount of nickel salt material was 1mL: (2-3) mol.

Preferably, the temperature of the hydrothermal reaction is 180-220 ℃; the hydrothermal reaction time is 1-3 hours.

Preferably, the hydrogen-containing atmosphere is an argon atmosphere containing 4 to 6 percent of hydrogen; the high-temperature calcination temperature is 300-500 ℃, and the high-temperature calcination heat preservation time is 0.5-2 hours.

The invention provides the carbon nano tube supported nickel-molybdenum alloy catalyst prepared by the preparation method, and the nickel-molybdenum alloy loading capacity is 55% -85%.

The present invention provides the use of a carbon nanotube supported nickel molybdenum alloy catalyst as described above as an anode catalyst in an anion exchange membrane fuel cell.

The invention provides a preparation method of a carbon nano tube supported nickel-molybdenum alloy catalyst, which comprises the following steps: a) Treating the carbon nanotubes by using a Hummers method to obtain treated carbon nanotubes; b) Mixing the treated carbon nano tube, polyvinylpyrrolidone, nickel salt, molybdate, alcohol and water, then dropwise adding ammonia water, reacting for 10-30 min, and performing hydrothermal reaction; c) And drying the product of the hydrothermal reaction, and calcining at high temperature in a hydrogen-containing atmosphere to obtain the carbon nano tube supported nickel-molybdenum alloy catalyst.

Compared with the prior art, the preparation method of the NiMo/CNT catalyst provided by the invention has the following advantages and positive effects:

(1) The preparation of the complete non-noble metal alkaline hydrogen oxidation catalyst is realized, the material sources are wide, the cost is low, and the environmental pollution is small;

(2) The electrochemical active area is increased by the carbon nano tube substrate load, and the exchange current density and the kinetic current density of the electrocatalytic alkaline hydrogen oxidation reaction are higher and are respectively 3.52mA/cm ² 、8.46mA/cm ² (overpotential 30 mV). The method comprises the steps of carrying out a first treatment on the surface of the

(3) Realize higher power density operation of the anion exchange membrane fuel cell with low noble metal loading, and peak power density is 436.24mW/cm ² 。

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are required to be used in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only embodiments of the present invention, and that other drawings can be obtained according to the provided drawings without inventive effort for a person skilled in the art.

FIG. 1 is an X-ray crystal diffraction pattern of a NiMo/CNT catalyst prepared in example 1 of the present invention;

FIG. 2 is a transmission electron micrograph of a NiMo/CNT catalyst prepared in example 1 of the present invention;

FIG. 3 is a graph showing the elemental distribution of a NiMo/CNT catalyst prepared in example 1 of this invention;

FIG. 4A is a graph showing the polarization curves of alkaline hydrogen oxidation reactions for the NiMo/CNT catalyst prepared in example 1 of the present invention, the nickel-molybdenum alloy materials obtained in comparative examples 1-3, and commercial 20% Pt/C; wherein, the current density refers to the geometric area current density of the rotary disk electrode, and the RHE refers to the reversible hydrogen electrode;

FIG. 4B shows the kinetic current density and exchange current density of the NiMo/CNT catalyst prepared in example 1 of the present invention, the nickel-molybdenum alloy material obtained in comparative example 1 and commercial 20% Pt/C;

FIG. 5 shows polarization curves of alkaline hydrogen oxidation reaction of the NiMo/CNT catalyst prepared in example 1 of the present invention and the nickel-molybdenum alloy material prepared in comparative example 1 before the accelerated durability test and after different cycles;

FIG. 6 is a graph showing the polarization curves of an anion exchange membrane fuel cell of the NiMo/CNT catalyst obtained in example 1 of the present invention and the nickel-molybdenum alloy material obtained in comparative example 1;

FIG. 7 is an X-ray crystal diffraction chart of NiMo/CNT catalysts obtained in examples 2 to 5 of the present invention;

FIG. 8 is a transmission electron micrograph of the NiMo/CNT catalysts obtained in examples 2-5 of this invention;

FIG. 9 is a graph showing the polarization of alkaline hydrogen oxidation reactions for NiMo/CNT catalysts obtained in examples 2-5 of this invention;

FIG. 10 is an X-ray crystal diffraction chart of NiMo/CNT catalysts obtained in examples 6 to 7 of the present invention;

FIG. 11 is a transmission electron micrograph of the NiMo/CNT catalysts obtained in examples 6-7 of this invention;

FIG. 12 is a graph showing the polarization of alkaline hydrogen oxidation reactions for NiMo/CNT catalysts obtained in examples 6 through 7 of this invention;

FIG. 13 is an X-ray crystal diffraction chart of a nickel-molybdenum alloy material obtained in comparative example 1 of the present invention;

FIG. 14 is a transmission electron micrograph of a nickel-molybdenum alloy material obtained in comparative example 1 of the present invention;

FIG. 15 is an X-ray crystal diffraction chart of a NiMo/CNT material obtained in comparative example 2 of the present invention;

FIG. 16 is a transmission electron micrograph of a NiMo/CNT material obtained in comparative example 2 of the present invention;

FIG. 17 is an X-ray crystal diffraction chart of a NiMo/CNT material obtained in comparative example 3 of the present invention;

FIG. 18 is a transmission electron micrograph of a NiMo/CNT material obtained in comparative example 3 of the present invention.

Detailed Description

The invention firstly adopts Hummers method to pretreat the carbon nano tube, oxidizes the surface of the carbon nano tube to form oxygen-containing groups (-OH, -COOH) with higher coverage, is beneficial to the dispersion in a reaction solvent and the adsorption of ions, further strengthens the interaction between NiMo particles and a carrier, and is more beneficial to the synthesis and catalytic stability of materials. The method comprises the following specific steps:

Preferably, the carbon nanotubes are added into concentrated sulfuric acid, stirred for 12 hours, sodium nitrate and potassium permanganate are added successively under the heating condition of an oil bath at 40 ℃, stirring is continued for 1 hour, deionized water is slowly added for dilution, then 30% hydrogen peroxide solution is added dropwise, later centrifugation and washing with 5% hydrochloric acid and deionized water are performed, and finally freeze drying is performed.

In the present invention, the carbon nanotubes are preferably multi-walled carbon nanotubes, the inner diameter of the carbon nanotubes is preferably 3 to 5nm, the outer diameter is preferably 8 to 15nm, the length is preferably 45 to 55 μm, and more preferably 50 μm; the mass ratio of the carbon nano tube to the concentrated sulfuric acid is preferably 1: (40 to 45), more preferably 1: (41 to 44), most preferably 1: (42-43); the mass ratio of the carbon nano tube to the sodium nitrate is (3-6): 1, more preferably (4 to 5): 1, a step of; the mass ratio of the carbon nano tube to the potassium permanganate is 1: (0.9 to 1.1), more preferably 1:1.

After the treated carbon nano tube is obtained, the treated carbon nano tube, polyvinylpyrrolidone, nickel salt and molybdate are added into a reaction device, and then alcohol and water are added for dispersion and dissolution under the stirring condition to obtain a mixed solution.

In the invention, the mass ratio of the carbon nano tube to the polyvinylpyrrolidone after the treatment is 10 (11-17), more preferably 10 (12-16), such as 10:12, 10:13, 10:14, 10:15, 10:16, preferably the range value with any value as the upper limit or the lower limit; the alcohol is preferably ethylene glycol, and the volume ratio of water to alcohol is preferably 1: (3-6), more preferably 1: (4-5); specifically, in the embodiment of the invention, the ratio of the water, the alcohol, the polyvinylpyrrolidone and the treated carbon nanotubes is preferably 1mL (3-6 mL) (11-17 mg) (9-10 mg), more preferably 1mL (4-5 mL) (12-16 mg:10mg.

The nickel salt is preferably nickel nitrate hexahydrate (Ni (NO ₃ ) ₂ ·6H ₂ O); the molybdate is preferably ammonium molybdate tetrahydrate ((NH) ₄ ) ₆ Mo ₇ O ₂₄ ·4H ₂ O), the mass ratio of the treated carbon nanotubes to the nickel salt is 1: (3-12), more preferably 1: (5-10), such as 1:3,1:4,1:5,1:6,1:7,1:8,1:9,1:10,1:11,1:12, preferably a range value having any of the above values as an upper limit or a lower limit; the mass ratio of the treated carbon nano tube to the molybdate is 1: (0.3 to 1.2), preferably 1: (0.5-1),the method comprises the following steps: 0.3,1:0.4,1:0.5,1:0.6,1:0.7,1:0.8,1:0.9,1:1,1:1.1,1:1.2, preferably a range value having any of the above values as an upper or lower limit; the molar ratio of the nickel salt to the molybdate is preferably (5-6): 1, such as 5:1,5.1:1,5.2:1,5.3:1,5.4:1,5.5:1,5.6:1,5.7:1,5.8:1,5.9:1,6:1, preferably a range value having any of the above values as an upper limit or a lower limit.

In the present invention, the concentration of the nickel salt in the mixed solution is preferably 20 to 60mmol/L, more preferably 30 to 50mmol/L, such as 20mmol/L,25mmol/L,30mmol/L,35mmol/L,40mmol/L,45mmol/L,50mmol/L,55mmol/L,60mmol/L, preferably a range value in which any of the above values is the upper limit or the lower limit; in the mixed solution, the concentration of the molybdate is preferably 0.52 to 1.55mmol/L, more preferably 0.8 to 1.2mmol/L, such as 0.52mmol/L,0.55mmol/L,0.6mmol/L,0.7mmol/L,0.8mmol/L,0.9mmol/L,1mmol/L,1.1mmol/L,1.2mmol/L,1.3mmol/L,1.4mmol/L,1.5mmol/L,1.55mmol/L, preferably a range having any of the above-mentioned values as an upper limit or a lower limit.

The application introduces polyvinylpyrrolidone and water in the synthesis process, and has promotion effect on the loading of nano particles. In one aspect, polyvinylpyrrolidone is a surfactant that serves as a bridge for the connection between the carbon nanotubes and metal ions to enhance adsorption of substrate ions. On the other hand, in view of the extremely small solubility of ammonium molybdate in alcohol, the process adds a small amount of water to promote the dissolution of the ammonium molybdate, which is beneficial to Ni ²⁺ 、Mo ₇ O ₂₄ ^6- Is mixed uniformly.

After stirring for 24 hours, ammonia water is added dropwise into the obtained mixed solution for reaction for 10-30 min, preferably 15-20 min, and then the solution is transferred to a hydrothermal kettle for hydrothermal reaction.

In the present invention, the concentration of the ammonia water is preferably 25 to 28%, more preferably 26 to 27%, and the ratio of the volume of the ammonia water to the amount of the substance of the nickel salt is preferably 1mL: (2-3) mol, more preferably 1mL: (2.2-2.8) mol, such as 1mL:2mol,1mL:2.1mol,2.2mol,1mL:2.3mol,1mL:2.4mol,1mL:2.5mol,1mL:2.6mol,1mL:2.7mol,1mL:2.8mol,1mL:2.9mol,1mL:3mol, preferably a range having any of the above values as an upper limit or a lower limit.

In the present invention, the temperature of the hydrothermal reaction is preferably 180 to 220 ℃, more preferably 190 to 210 ℃, such as 180 ℃,185 ℃,190 ℃,195 ℃,200 ℃,205 ℃,210 ℃,215 ℃,220 ℃, preferably a range value with any of the above values as an upper limit or a lower limit; the time of the hydrothermal reaction is preferably 1 to 3 hours, more preferably 2 to 3 hours.

After the hydrothermal reaction is finished, the precursor is obtained by cooling and centrifuging, washing with deionized water and ethanol and finally vacuum drying.

The precursor is subjected to high-temperature calcination in a hydrogen-containing atmosphere to obtain the carbon nano tube supported nickel-molybdenum alloy catalyst NiMo/CNT.

In the present invention, the hydrogen-containing atmosphere is preferably a mixture of hydrogen and argon, wherein the volume fraction of hydrogen is preferably 4 to 6%, more preferably 5 to 6%, and calcination in the hydrogen-containing atmosphere can reduce nickel-molybdenum hydroxide in the precursor to nickel-molybdenum alloy particles, and calcination reduction is performed at a relatively low temperature (400 ℃) to prevent the sintering of the nanoparticles from becoming large due to an excessive temperature.

The temperature of the high-temperature calcination is preferably 300 to 500 ℃, more preferably 350 to 450 ℃, such as 300 ℃,350 ℃,400 ℃,450 ℃,500 ℃, preferably a range value with any of the above values as an upper limit or a lower limit; the heating rate is preferably 1 to 5 ℃/min, more preferably 2 to 3 ℃/min, and the heat-preserving time of the high-temperature calcination is preferably 0.5 to 2 hours, more preferably 1 to 1.5 hours.

The invention realizes the load of nickel-molybdenum hydroxide on the carbon nano tube by using a common hydrothermal method, the high-pressure environment created by the hydrothermal kettle is beneficial to the formation and uniform distribution of hydroxide, and the temperature control can be realized accurately, and the method is simple and the equipment is simple.

The invention also provides a carbon nano tube supported nickel-molybdenum alloy catalyst, which is prepared according to the preparation method, wherein the carbon nano tube supported nickel-molybdenum alloy catalyst NiMo/CNT is of a nano tube morphology with embedded particles about 10nm, the particles are uniformly distributed, the loading capacity of the nickel-molybdenum alloy is preferably 55% -85%, such as 55%,60%,65%,70%,75%,80%,85%, and preferably the range value with any value as the upper limit or the lower limit.

The invention also provides application of the carbon nano tube supported nickel-molybdenum alloy catalyst as an anode catalyst in an anion exchange membrane fuel cell.

In the present invention, the catalyst is preferably used in an amount of 1mg/cm on the rotating disk electrode ² The amount to be used on the membrane electrode is preferably 12mg/cm ² 。

In order to further illustrate the present invention, the following examples are provided to describe in detail a carbon nanotube supported nickel-molybdenum alloy catalyst, its preparation method and application, but they should not be construed as limiting the scope of the present invention.

The chemical reagent used in the invention has no special requirement and is commercially available; the ionomer is Alkymer I-250, the anion exchange membrane is Alkymer W-25, and the ionomer is produced by Huizhou Yi Lai energy Co Ltd; the carbon paper model used was Sigracet SGL 29BC.

Examples 1 to 7 and comparative examples 1 and 3 were prepared by treating carbon nanotubes as follows:

1g of carbon nanotubes was added to 23mL of concentrated sulfuric acid and stirred for 12 hours. 200mg of sodium nitrate was added under heating in an oil bath at 40℃and after 5min 1g of potassium permanganate was slowly added and stirring was continued for 1 hour. Then 3mL of deionized water is slowly added, after 5min, 3mL of deionized water is slowly added, then 40mL of deionized water is poured over 5min, the oil bath is removed, and 140mL of deionized water is poured. 10mL of 30% hydrogen peroxide solution was added dropwise and stirred for 5min. The above process requires that the temperature be kept below 45 ℃ at all times. The dispersion was centrifuged, washed 2 times with 5% hydrochloric acid, several times with deionized water until the supernatant was neutral, and finally freeze-dried.

Example 1

70mg of polyvinylpyrrolidone and 50mg of the treated carbon nanotube were added to a beaker, 0.436g of nickel nitrate hexahydrate and 0.048g of ammonium molybdate tetrahydrate were further added, and the mixture was sonicated with 25mL of ethylene glycol and 5mL of deionized water for 1 hour to perform dispersion dissolution, and stirred for 24 hours. Slowly dropwise adding 0.625mL of ammonia water, reacting for 20min, transferring to a hydrothermal kettle, heating at 200 ℃ for 2 hours, cooling and centrifuging. Washing with deionized water for 3 times, washing with ethanol for 2 times, and finally vacuum drying to obtain the precursor. Placing the precursor in a porcelain boat, placing in a tube furnace, and continuously introducing 5% H ₂ Ar is heated to 400 ℃ at the speed of 3 ℃/min, and is naturally cooled after heat preservation for 1 hour, thus obtaining the product NiMo/CNT.

The NiMo/CNT prepared in example 1 was analyzed by X-ray diffraction to obtain an X-ray crystal diffraction pattern thereof, as shown in fig. 1.

The NiMo/CNT prepared in example 1 was analyzed by transmission electron microscopy to obtain a transmission electron micrograph thereof, as shown in fig. 2.

The NiMo/CNT prepared in example 1 was analyzed by transmission electron microscopy and X-ray spectroscopy to obtain its elemental distribution, as shown in fig. 3.

5mg of NiMo/CNT is weighed, 20 mu L of 5% Nafion solution and 480 mu L of isopropanol are added, and the catalyst is uniformly dispersed by ultrasonic treatment for 30 min. 20. Mu.L of the dispersion was applied dropwise to the rotating disk electrode. The rotary disk electrode is used as a working electrode, ag/AgCl is used as a reference electrode, a carbon rod is used as a counter electrode, 0.1mol/L KOH aqueous solution is used as electrolyte solution, hydrogen is bubbled into the electrolyte solution until the electrolyte solution is saturated, and alkaline hydrogen oxidation reaction test is carried out at the rotating speed of 160 r.p.m. As shown in fig. 4A and 4B, the NiMo/CNT current density is higher and reaches the diffusion limited current density plateau faster in example 1; analytical calculation, the exchange current density of NiMo/CNT in example 1 was 3.52mA/cm ^-2 Kinetic current density at 30mV overpotential was 8.46mA/cm ^-2 . As a result of the accelerated durability test in the 0.05-0.15V region, the activity loss of NiMo/CNT in example 1 was small after 12000 cycles as shown in FIG. 5.

60mg of NiMo/CNT is reacted with 300. Mu.L of ionomer,Mixing 4mL of ethanol, and performing ultrasonic treatment to form a dispersion liquid 1; 5mg of 40% Pt/C was mixed with 25. Mu.L of ionomer, 1mL of ethanol and sonicated to form dispersion 2. Spraying the dispersion 1 and the dispersion 2 on 5cm ² The anion exchange membrane of (2) is further immersed in a 1mol/L NaOH solution at 60 ℃ for 12 hours. Then the catalyst coated membrane is sandwiched between carbon papers and assembled with bipolar plate gas flow channels to form a single cell with NiMo/CNT side as anode and Pt/C side as cathode. The cell was heated to 95℃and 80% humidity hydrogen was fed to the anode at a flow rate of 0.8L/min, 100% humidity oxygen was fed to the cathode at a flow rate of 1.6L/min, and a 200kPa back pressure was applied to the gas outlet. The cell was tested for polarization curve with a fuel cell workstation as shown in FIG. 6, with a maximum power density of 436.24mW/cm ² 。

Example 2

70mg of polyvinylpyrrolidone and 50mg of the treated carbon nanotube were added to a beaker, 0.174g of nickel nitrate hexahydrate and 0.019g of ammonium molybdate tetrahydrate were further added, and the mixture was sonicated with 25mL of ethylene glycol and 5mL of deionized water for 1 hour to perform dispersion dissolution, and stirred for 24 hours. Slowly dropwise adding 0.250mL of ammonia water, reacting for 20min, transferring to a hydrothermal kettle, heating at 200 ℃ for 2 hours, cooling and centrifuging. Washing with deionized water for 3 times, washing with ethanol for 2 times, and finally vacuum drying to obtain the precursor. Placing the precursor in a porcelain boat, placing in a tube furnace, and continuously introducing 5% H ₂ Ar is heated to 400 ℃ at the speed of 3 ℃/min, and is naturally cooled after heat preservation for 1 hour, thus obtaining the product NiMo/CNT.

The NiMo/CNT prepared in example 2 was analyzed by X-ray diffraction to obtain an X-ray crystal diffraction pattern thereof, as shown in fig. 7.

The NiMo/CNT prepared in example 2 was analyzed by transmission electron microscopy to obtain a transmission electron micrograph thereof, as shown in fig. 8.

The NiMo/CNT prepared in example 2 was tested using a rotating disk electrode to obtain its alkaline hydrogen oxidation polarization curve as shown in fig. 9.

Example 3

70mg of polyvinylpyrrolidone and 50mg of the treated carbon nanotubes were added to a beaker, followed by 0.262g of nickel nitrate hexahydrate and 0.029g of tetrahydrateAmmonium molybdate hydrate was dissolved by ultrasonic treatment with 25mL of ethylene glycol and 5mL of deionized water for 1 hour, and stirred for 24 hours. Slowly dropwise adding 0.375mL of ammonia water, reacting for 20min, transferring to a hydrothermal kettle, heating at 200 ℃ for 2 hours, cooling and centrifuging. Washing with deionized water for 3 times, washing with ethanol for 2 times, and finally vacuum drying to obtain the precursor. Placing the precursor in a porcelain boat, placing in a tube furnace, and continuously introducing 5% H ₂ Ar is heated to 400 ℃ at the speed of 3 ℃/min, and is naturally cooled after heat preservation for 1 hour, thus obtaining the product NiMo/CNT.

The NiMo/CNT prepared in example 3 was analyzed by X-ray diffraction to obtain an X-ray crystal diffraction pattern thereof, as shown in fig. 7.

The NiMo/CNT prepared in example 3 was analyzed by transmission electron microscopy to obtain a transmission electron micrograph thereof, as shown in fig. 8.

The NiMo/CNT prepared in example 3 was tested using a rotating disk electrode to obtain its alkaline hydrogen oxidation polarization curve as shown in fig. 9.

Example 4

70mg of polyvinylpyrrolidone and 50mg of the treated carbon nanotube were added to a beaker, 0.349g of nickel nitrate hexahydrate and 0.038g of ammonium molybdate tetrahydrate were further added, and the mixture was sonicated with 25mL of ethylene glycol and 5mL of deionized water for 1 hour to disperse and dissolve, and stirred for 24 hours. Slowly dropwise adding 0.500mL of ammonia water, reacting for 20min, transferring to a hydrothermal kettle, heating at 200 ℃ for 2 hours, cooling and centrifuging. Washing with deionized water for 3 times, washing with ethanol for 2 times, and finally vacuum drying to obtain the precursor. Placing the precursor in a porcelain boat, placing in a tube furnace, and continuously introducing 5% H ₂ Ar is heated to 400 ℃ at the speed of 3 ℃/min, and is naturally cooled after heat preservation for 1 hour, thus obtaining the product NiMo/CNT.

The NiMo/CNT prepared in example 4 was analyzed by X-ray diffraction to obtain an X-ray crystal diffraction pattern thereof, as shown in fig. 7.

The NiMo/CNT prepared in example 4 was analyzed by transmission electron microscopy to obtain a transmission electron micrograph thereof, as shown in fig. 8.

The NiMo/CNT prepared in example 4 was tested using a rotating disk electrode to obtain its alkaline hydrogen oxidation polarization curve as shown in fig. 9.

Example 5

70mg of polyvinylpyrrolidone and 50mg of the treated carbon nanotube were added to a beaker, 0.523g of nickel nitrate hexahydrate and 0.058g of ammonium molybdate tetrahydrate were further added, and the mixture was sonicated with 25mL of ethylene glycol and 5mL of deionized water for 1 hour to perform dispersion dissolution, and stirred for 24 hours. Slowly dropwise adding 0.750mL of ammonia water, reacting for 20min, transferring to a hydrothermal kettle, heating at 200 ℃ for 2 hours, cooling and centrifuging. Washing with deionized water for 3 times, washing with ethanol for 2 times, and finally vacuum drying to obtain the precursor. Placing the precursor in a porcelain boat, placing in a tube furnace, and continuously introducing 5% H ₂ Ar is heated to 400 ℃ at the speed of 3 ℃/min, and is naturally cooled after heat preservation for 1 hour, thus obtaining the product NiMo/CNT.

The NiMo/CNT prepared in example 5 was analyzed by X-ray diffraction to obtain an X-ray crystal diffraction pattern thereof, as shown in fig. 7.

The NiMo/CNT prepared in example 5 was analyzed by transmission electron microscopy to obtain a transmission electron micrograph thereof, as shown in fig. 8.

The NiMo/CNT prepared in example 5 was tested using a rotating disk electrode to obtain its alkaline hydrogen oxidation polarization curve as shown in fig. 9.

Example 6

70mg of polyvinylpyrrolidone and 50mg of the treated carbon nanotube were added to a beaker, 0.436g of nickel nitrate hexahydrate and 0.048g of ammonium molybdate tetrahydrate were further added, and the mixture was sonicated with 25mL of ethylene glycol and 5mL of deionized water for 1 hour to perform dispersion dissolution, and stirred for 24 hours. Slowly dropwise adding 0.625mL of ammonia water, reacting for 20min, transferring to a hydrothermal kettle, heating at 200 ℃ for 2 hours, cooling and centrifuging. Washing with deionized water for 3 times, washing with ethanol for 2 times, and finally vacuum drying to obtain the precursor. Placing the precursor in a porcelain boat, placing in a tube furnace, and continuously introducing 5% H ₂ Ar is heated to 300 ℃ at the speed of 3 ℃/min, and is naturally cooled after heat preservation for 1 hour, thus obtaining the product NiMo/CNT.

The NiMo/CNT prepared in example 6 was analyzed by X-ray diffraction to obtain an X-ray crystal diffraction pattern thereof, as shown in fig. 10.

The NiMo/CNT prepared in example 6 was analyzed by transmission electron microscopy to obtain a transmission electron micrograph thereof, as shown in fig. 11.

The NiMo/CNT prepared in example 6 was tested using a rotating disk electrode to obtain its alkaline hydrogen oxidation polarization curve as shown in fig. 12.

Example 7

70mg of polyvinylpyrrolidone and 50mg of the treated carbon nanotube were added to a beaker, 0.436g of nickel nitrate hexahydrate and 0.048g of ammonium molybdate tetrahydrate were further added, and the mixture was sonicated with 25mL of ethylene glycol and 5mL of deionized water for 1 hour to perform dispersion dissolution, and stirred for 24 hours. Slowly dropwise adding 0.625mL of ammonia water, reacting for 20min, transferring to a hydrothermal kettle, heating at 200 ℃ for 2 hours, cooling and centrifuging. Washing with deionized water for 3 times, washing with ethanol for 2 times, and finally vacuum drying to obtain the precursor. Placing the precursor in a porcelain boat, placing in a tube furnace, and continuously introducing 5% H ₂ Ar is heated to 500 ℃ at the speed of 3 ℃/min, and is naturally cooled after heat preservation for 1 hour, thus obtaining the product NiMo/CNT.

The NiMo/CNT prepared in example 7 was analyzed by X-ray diffraction to obtain an X-ray crystal diffraction pattern thereof, as shown in fig. 10.

The NiMo/CNT prepared in example 7 was analyzed by transmission electron microscopy to obtain a transmission electron micrograph thereof, as shown in fig. 11.

The diffraction peak of NiMo/CNT prepared in example 7 became sharper than that of other examples, and it was confirmed that the reason for this was that the alloy particle size became large and the crystallinity increased due to the higher calcination temperature in combination with the transmission electron micrograph.

The NiMo/CNT prepared in example 7 was tested using a rotating disk electrode to obtain its alkaline hydrogen oxidation polarization curve as shown in fig. 12.

Comparative example 1

70mg of polyvinylpyrrolidone was added to the beaker, followed by 0.436g of nickel nitrate hexahydrate and 0.048g of ammonium molybdate tetrahydrate, and the mixture was sonicated with 25mL of ethylene glycol and 5mL of deionized water for 1 hour to perform dispersion dissolution. Slowly dropwise adding 0.625mL of ammonia water under stirring, reacting for 20min, transferring to a hydrothermal kettle, heating at 200 ℃ for 2 hours, cooling, and separatingAnd (5) a heart. Washing with deionized water for 3 times, washing with ethanol for 2 times, and finally vacuum drying to obtain the precursor. Placing the precursor in a porcelain boat, placing in a tube furnace, and continuously introducing 5%H ₂ Ar is heated to 400 ℃ at the speed of 3 ℃/min, and is naturally cooled after heat preservation for 1 hour, thus obtaining the product NiMo.

The NiMo prepared in comparative example 1 was analyzed by X-ray diffraction to obtain an X-ray crystal diffraction pattern thereof, as shown in fig. 13.

The NiMo prepared in comparative example 1 was analyzed by a transmission electron microscope to obtain a transmission electron micrograph thereof, as shown in fig. 14. The particles of the material are larger, interlinked, compared to the examples, and do not facilitate the exposure of the active sites.

5mg of NiMo was weighed, 20. Mu.L of 5% Nafion solution and 480. Mu.L of isopropyl alcohol were added, and the catalyst was uniformly dispersed by sonication for 30 min. 20. Mu.L of the dispersion was applied dropwise to the rotating disk electrode. The alkaline hydrogen oxidation activity was subsequently tested according to the method in example 1. As shown in FIG. 4, the exchange current density of NiMo prepared in comparative example 1 was 2.93mA/cm ^-2 Kinetic current density at 30mV overpotential was 7.43mA/cm ^-2 Are lower than in the examples. As a result of the accelerated durability test in the range of 0.05 to 0.15V, as shown in FIG. 5, the activity loss of NiMo prepared in comparative example 1 was large and the stability was significantly weaker than that of example 1 after 12000 cycles.

48mg of NiMo, 12mg of conductive carbon black and 300 mu L of ionomer and 4mL of ethanol are mixed and ultrasonic formed into a dispersion liquid 1; 5mg of 40% Pt/C was mixed with 25. Mu.L of ionomer, 1mL of ethanol and sonicated to form dispersion 2. A membrane electrode assembly was subsequently prepared and tested for anion exchange membrane fuel cell performance in accordance with the method in example 1. As shown in FIG. 6, the maximum power density is 260.06mW/cm ² Only 0.6 times that of the examples.

Comparative example 2

Unlike examples 1 to 7 and comparative examples 1 and 3, comparative example 2 uses piranha solution (concentrated sulfuric acid and hydrogen peroxide mixed solution) to treat carbon nanotubes, specifically as follows: 56mL of 98% concentrated sulfuric acid was added to 24mL of 30% hydrogen peroxide solution, and 80mL piranha solution was prepared. 1g of carbon nanotube is placed in a 250mL flask, 80mL piranha solution is added, 100mL deionized water is added for dilution after stirring for 5 hours, then the mixture is centrifuged, the mixture is washed with deionized water for a plurality of times until the supernatant is neutral, then ethanol is used for washing for 1 time, and finally the mixture is dried in vacuum at 50 ℃.

The NiMo/CNT prepared in comparative example 2 was analyzed by X-ray diffraction to obtain an X-ray crystal diffraction pattern thereof, as shown in fig. 15.

The NiMo/CNT prepared in comparative example 2 was analyzed by transmission electron microscopy to obtain a transmission electron micrograph thereof, as shown in fig. 16.

The NiMo/CNT prepared in comparative example 2 was tested using a rotating disk electrode to obtain its alkaline hydrogen oxidation polarization curve as shown in fig. 1.

It can be seen that NiMo/CNT prepared from carbon nanotubes treated with piranha solution had non-uniform distribution of alloy particles and less particle loading, resulting in lower catalytic activity.

Comparative example 3

Unlike examples 1 to 7 and comparative examples 1 and 2, the surfactant used in comparative example 3 was cetyltrimethylammonium bromide, not polyvinylpyrrolidone. 230mg of cetyltrimethylammonium bromide and 50mg of the treated carbon nanotubes (treatment method was the same as in examples 1 to 7 and comparative example 1) were added to a beaker, 0.436g of nickel nitrate hexahydrate and 0.048g of ammonium molybdate tetrahydrate were further added, and the mixture was sonicated with 25mL of ethylene glycol and 5mL of deionized water for 1 hour to disperse and dissolve, and stirred for 24 hours.Slowly dropwise adding 0.625mL of ammonia water, reacting for 20min, transferring to a hydrothermal kettle, heating at 200 ℃ for 2 hours, cooling and centrifuging. Washing with deionized water for 3 times, washing with ethanol for 2 times, and finally vacuum drying to obtain the precursor. Placing the precursor in a porcelain boat, placing in a tube furnace, and continuously introducing 5% H ₂ Ar is heated to 400 ℃ at the speed of 3 ℃/min, and is naturally cooled after heat preservation for 1 hour, thus obtaining the product NiMo/CNT.

The NiMo/CNT prepared in comparative example 3 was analyzed by X-ray diffraction to obtain an X-ray crystal diffraction pattern thereof, as shown in fig. 17.

The NiMo/CNT prepared in comparative example 3 was analyzed by a transmission electron microscope to obtain a transmission electron micrograph thereof, as shown in fig. 18.

The NiMo/CNT prepared in comparative example 3 was tested using a rotating disk electrode to obtain its alkaline hydrogen oxidation polarization curve as shown in fig. 1.

As can be seen from sharper diffraction peaks and electron micrographs, the NiMo/CNT prepared in comparative example 3 has the problems of larger particle size, uneven particle adhesion and the like, and is unfavorable for exposure of active sites, which indicates that the adsorption effect of hexadecyl trimethyl ammonium bromide on metal ions in the synthesis process is inferior to that of polyvinylpyrrolidone in the example.

The foregoing is merely a preferred embodiment of the present invention and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the present invention, which are intended to be comprehended within the scope of the present invention.

Claims

1. The preparation method of the carbon nano tube supported nickel-molybdenum alloy catalyst comprises the following steps:

2. The method of claim 1, wherein the carbon nanotubes are treated by Hummers method according to the steps of:

3. The method according to claim 1, wherein the carbon nanotubes are multi-walled carbon nanotubes having an inner diameter of 3 to 5nm, an outer diameter of 8 to 15nm, and a length of 45 to 55 μm.

4. The method according to claim 1, wherein the volume ratio of water to alcohol is 1: (3-6); the mass ratio of the polyvinylpyrrolidone to the treated carbon nano tube is (11-17): 10.

5. the method of claim 1, wherein the molar ratio of nickel salt to molybdate is (5 to 6): 1, a step of;

6. The method according to claim 1, wherein the concentration of the aqueous ammonia is 25 to 28%;

7. The method of claim 1, wherein the hydrothermal reaction is at a temperature of 180-220 ℃; the hydrothermal reaction time is 1-3 hours.

8. The method according to claim 1, wherein the hydrogen-containing atmosphere is an argon atmosphere containing 4 to 6% of hydrogen; the high-temperature calcination temperature is 300-500 ℃, and the high-temperature calcination heat preservation time is 0.5-2 hours.

9. The preparation method of any one of claims 1-8, wherein the carbon nanotube supported nickel-molybdenum alloy catalyst has a nickel-molybdenum alloy loading of 55% -85%.

10. The use of the carbon nanotube-supported nickel-molybdenum alloy catalyst of claim 9 as an anode catalyst in an anion exchange membrane fuel cell.