CN116288461A

CN116288461A - AB-bit co-doped perovskite nanofiber catalyst and preparation method and application thereof

Info

Publication number: CN116288461A
Application number: CN202310339335.5A
Authority: CN
Inventors: 彭强祥; 王书宸; 王春栋
Original assignee: Xiangtan University
Current assignee: Xiangtan University
Priority date: 2023-04-03
Filing date: 2023-04-03
Publication date: 2023-06-23

Abstract

The invention belongs to the technical field of new energy of electrochemical energy storage, and provides an AB-bit co-doped perovskite nanofiber catalyst, and a preparation method and application thereof. The preparation method comprises the following steps: s1, mixing lanthanum nitrate hexahydrate, strontium nitrate, ferric nitrate nonahydrate, iridium trichloride, N-dimethylformamide and polyvinylpyrrolidone to obtain a polymer solution; s2, carrying out electrostatic spinning treatment on the polymer solution to obtain a nanofiber polymer precursor; and S3, calcining the nanofiber polymer precursor to obtain the AB-bit co-doped perovskite nanofiber catalyst. The invention adopts A-site strontium doping and B-site iridium doping to realize the preparation of AB-site co-doped iron-based perovskite so as to improve the oxygen evolution capability of the catalyst in OER, and prepares the catalyst by adopting an electrostatic spinning method and calcination treatment, so that the cost is low, the noble metal consumption is less, the environment is not polluted, and the catalyst can be prepared in a large scale.

Description

AB-bit co-doped perovskite nanofiber catalyst and preparation method and application thereof

Technical Field

The invention relates to the technical field of new energy for electrochemical energy storage, in particular to an AB co-doped perovskite nanofiber catalyst and a preparation method and application thereof.

Background

Excessive development of traditional fossil energy sources such as coal, petroleum, natural gas and the like causes serious environmental pollution. For many years, in order to alleviate the energy crisis of environmental pollution and the increasing exhaustion of non-renewable energy sources, many technologies have been developed to reduce the consumption of energy sources in order to more reasonably and effectively utilize the energy sources and reduce the emission of pollutants. Therefore, development and utilization of efficient, low-cost clean energy is a major approach to replace fossil energy and to alleviate environmental pollution problems. There is growing interest in the use of renewable energy sources such as hydropower, tidal energy, solar energy, hydrogen energy, and the like. Intermittent energy sources such as solar energy, tidal energy, wind energy and the like are affected by various factors, cannot be continuously generated, and can prevent continuous utilization of energy sources in life production. Therefore, if it is possible to store surplus energy when the intermittent energy source is large and to use the stored energy when it is needed, the above-mentioned problems can be effectively solved. Hydrogen is used as a clean energy carrier, has the characteristics of rich reserves, high combustion value, no carbon emission and the like, and can also be used for producing high-value chemicals. The electrochemical water decomposition hydrogen production can realize the full utilization of sustainable renewable energy and realize the zero emission of carbon.

Oxygen evolution reactions (Oxygen Evolution Reaction, OER) are important half reactions of electrochemical water splitting hydrogen production processes that convert electrical energy into hydrogen fuel, which can be from intermittent energy sources such as solar, tidal and wind. However, due to the slow kinetics of OER, the catalytic barrier is high, and a large overpotential is typically required to drive water splitting. Therefore, the optimization of the OER electrocatalyst performance is important to improve the hydrogen production efficiency by electrochemical water decomposition, and the proper catalyst can make the process of electrochemical water decomposition more efficient and energy-saving. In order to reduce the overpotential and improve the efficiency, developing an efficient oxygen evolution reaction electrocatalyst is a hot spot of current research. Iridium dioxide (IrO) ₂ ) And ruthenium dioxide (RuO) ₂ ) As a commercial oxygen evolution reaction catalyst, it is recognized that it has excellent oxygen evolution reaction catalytic performance. However, iridium and ruthenium are noble metals with very rare crust content, and the high price leads to high use cost, and the defects of poor stability and the like, so that the large-scale application of the iridium and ruthenium is severely limited. Based on this, development is efficient and low-costCatalysts which are rich in reserves and have good stability are very important.

In recent years, OER activity and stability of transition metals and their compounds in alkaline solutions have been widely studied. Perovskite (ABO) ₃ The A-position on the 12-coordinate is usually rare earth or alkali metal, and the B-position on the 6-coordinate is usually transition metal) is considered as one of the most promising OER catalysts as a material with low cost, adjustable composition, stable structure and high activity. However, in the industrial application of catalysts, the OER catalytic properties inherent to perovskite are not satisfactory, in particular the electrocatalytic capacity and stability under alkaline conditions.

Therefore, how to provide a perovskite nanofiber catalyst with good stability and high catalytic activity is a problem to be solved by those skilled in the art.

Disclosure of Invention

In view of the above, the invention provides an AB-bit co-doped perovskite nanofiber catalyst, and a preparation method and application thereof. On one hand, the aim is to solve the technical problems of rare noble metal, high price and poor poisoning resistance in the existing noble metal catalyst; on the other hand, the technical problems of poor stability and poor catalytic performance of the existing perovskite material catalyst are solved.

In order to achieve the above purpose, the invention adopts the following technical scheme:

the invention provides a preparation method of an AB-bit co-doped perovskite nanofiber catalyst, which comprises the following steps:

s1, mixing lanthanum nitrate hexahydrate, strontium nitrate, ferric nitrate nonahydrate, iridium trichloride, N-dimethylformamide and polyvinylpyrrolidone to obtain a polymer solution;

s2, carrying out electrostatic spinning treatment on the polymer solution to obtain a nanofiber polymer precursor;

and S3, calcining the nanofiber polymer precursor to obtain the AB-bit co-doped perovskite nanofiber catalyst.

Further, the mol volume ratio of the lanthanum nitrate hexahydrate, the strontium nitrate, the ferric nitrate nonahydrate, the iridium trichloride and the N, N-dimethylformamide is 0.5-1.0 mmol:0.5 to 1.0mmol:1.38 to 1.47mmol:0.03 to 0.12mmol: 10-15 mL; the mass volume ratio of the polyvinylpyrrolidone to the N, N-dimethylformamide is 1-2 g: 10-15 mL.

Further, the temperature of the mixing in the step S1 is 40-60 ℃, and the mixing time is 8-15 h.

Further, the parameters of the electrostatic spinning treatment are as follows: the liquid injection speed is 0.4-0.6 mL/h, the distance between the needle tip and the collecting device is 15-18 cm, and the working voltage is 15-18 kV.

Further, the calcination treatment is divided into two stages, wherein the temperature of the first stage is 200-300 ℃, and the heat preservation time of the first stage is 1.5-2.5 hours; the temperature of the second stage is 750-850 ℃, and the heat preservation time of the second stage is 2.5-3.5 h.

Further, the temperature rising rate of the room temperature to the temperature of the first stage is 1-5 ℃/min, and the temperature rising rate of the temperature of the first stage to the temperature of the second stage is 1-5 ℃/min.

The invention provides the AB-bit co-doped perovskite nanofiber catalyst prepared by the preparation method.

The invention also provides application of the AB-bit co-doped perovskite nanofiber catalyst in oxygen evolution reaction.

Compared with the prior art, the invention has the following beneficial effects:

the invention adopts A-site strontium doping and B-site iridium doping to realize the preparation of AB-site co-doped iron-based perovskite so as to improve the oxygen evolution capability of the catalyst in OER, and prepares the catalyst by adopting an electrostatic spinning method and calcination treatment, so that the cost is low, the noble metal consumption is less, the environment is not polluted, and the catalyst can be prepared in a large scale;

according to the invention, the morphology of the hollow nanofiber formed by the N, N-dimethylformamide and polyvinylpyrrolidone is regulated and controlled by the proportion of the N, N-dimethylformamide and polyvinylpyrrolidone, so that the OER oxygen evolution performance of the catalyst is regulated. When the mass volume ratio of polyvinylpyrrolidone to N, N-dimethylformamide is 1-2 g: 10-15 mL, the obtained hollow nanofiber perovskite catalyst has the advantages of best appearance, larger surface area and more active site number.

Drawings

FIG. 1 is a drawing of La prepared in example 1 of the present invention _0.6 Sr _0.4 Fe _0.96 Ir _0.04 O _3-σ Schematic process diagram of the catalyst;

FIG. 2 is a La prepared in example 1 of the present invention _0.6 Sr _0.4 Fe _0.96 Ir _0.04 O _3-σ XRD pattern of the catalyst;

FIG. 3 is a La prepared in example 1 of the present invention _0.6 Sr _0.4 Fe _0.96 Ir _0.04 O _3-σ SEM image of the catalyst;

FIG. 4 is a La prepared in example 1 of the present invention _0.6 Sr _0.4 Fe _0.96 Ir _0.04 O _3-σ TEM image of catalyst;

FIG. 5 is a La prepared in example 1 of the present invention _0.6 Sr _0.4 Fe _0.96 Ir _0.04 O _3-σ EDS energy spectrum of the catalyst;

FIG. 6 shows the catalysts obtained in examples 1 to 4 of the present invention and LaFeO in comparative example 1 ₃ A performance test comparison graph of the catalyst in the catalytic oxygen evolution reaction;

FIG. 7 is a diagram of La prepared in example 1 of the present invention _0.6 Sr _0.4 Fe _0.96 Ir _0.04 O _3-σ Catalyst and commercial catalyst RuO ₂ Performance test comparative graph in catalytic oxygen evolution reaction.

Detailed Description

In the invention, the mol volume ratio of the lanthanum nitrate hexahydrate, the strontium nitrate, the ferric nitrate nonahydrate, the iridium trichloride and the N, N-dimethylformamide is 0.5-1.0 mmol:0.5 to 1.0mmol:1.38 to 1.47mmol:0.03 to 0.12mmol:10 to 15mL, preferably 0.6 to 0.9mmol:0.6 to 0.9mmol:1.4 to 1.46mmol:0.05 to 0.1mmol: 11-14 mL; more preferably 0.7 to 0.8mmol:0.7 to 0.8mmol:1.42 to 1.44mmol: 0.06-0.08 mmol: 12-13 mL.

In the invention, the mass-volume ratio of polyvinylpyrrolidone to N, N-dimethylformamide is 1-2 g: 10-15 mL, preferably 1.2-1.8 g:11 to 14mL, more preferably 1.4 to 1.6g: 12-13 mL.

In the present invention, the temperature of the mixing in the step S1 is 40 to 60 ℃, preferably 45 to 55 ℃, and more preferably 48 to 52 ℃; the mixing time is 8 to 15 hours, preferably 9 to 14 hours, more preferably 10 to 12 hours.

In the invention, the parameters of the electrostatic spinning treatment are as follows: the liquid injection speed is 0.4-0.6 mL/h, preferably 0.45-0.55 mL/h, and more preferably 0.55mL/h; the distance between the needle tip and the collecting device is 15-18 cm, preferably 16-17 cm; the operating voltage is 15 to 18kV, preferably 16 to 17kV.

In the invention, the needle model of the plastic injector for electrostatic spinning treatment is 23-G.

In the invention, the receiving substrate of the collecting device is release paper.

In the present invention, the calcination treatment is divided into two stages, wherein the temperature of the first stage is 200 to 300 ℃, preferably 220 to 280 ℃, and more preferably 240 to 260 ℃; the heat preservation time in the first stage is 1.5-2.5 h, preferably 1.6-2.4 h, and more preferably 1.8-2.2 h; the temperature in the second stage is 750-850 ℃, preferably 770-830 ℃, and more preferably 780-800 ℃; the second stage is carried out for a period of 2.5 to 3.5 hours, preferably 2.7 to 3.2 hours, more preferably 2.8 to 3.0 hours.

In the present invention, the temperature rise rate at which the room temperature is raised to the temperature of the first stage is 1 to 5 ℃/min, preferably 2 to 4 ℃/min, and more preferably 3 ℃/min; the temperature rising rate of the temperature in the first stage to the temperature in the second stage is 1 to 5℃per minute, preferably 2 to 4℃per minute, and more preferably 3℃per minute.

The following description of the technical solutions in the embodiments of the present invention will be clear and complete, and it is obvious that the described embodiments are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

Example 1

Adding 0.9mmol of lanthanum nitrate hexahydrate, 0.6mmol of strontium nitrate, 1.44mmol of ferric nitrate nonahydrate and 0.06mmol of iridium trichloride into a container filled with 10mL of N, N-dimethylformamide, stirring in a water bath at 50 ℃ for 15 minutes until the mixture is completely and uniformly dissolved, adding 1.42g of polyvinylpyrrolidone into the mixed solution, and stirring for 10 hours until the mixture is uniformly dissolved to obtain a viscous polymer solution;

transferring the viscous polymer solution into a plastic injector with the volume of 10mL for electrostatic spinning, wherein the parameters of the electrostatic spinning are as follows: the liquid injection speed is 0.5mL/h, the distance between the needle point and the collecting device is 15cm, the working voltage is 15kV, and after the electrostatic spinning treatment is completed, the release paper on the electrostatic spinning receiving device is taken down, and the release paper is separated to obtain a nanofiber polymer precursor;

calcining nanofiber polymer precursor in a muffle furnace, heating to 200 ℃ at a speed of 2 ℃/min in an air atmosphere, maintaining for 2h, heating to 800 ℃ at a speed of 2 ℃/min, maintaining for 3h, naturally cooling to room temperature, and grinding to obtain La _0.6 Sr _0.4 Fe _0.96 Ir _0.04 O _3-σ A catalyst.

FIG. 2 shows La prepared in this example _0.6 Sr _0.4 Fe _0.96 Ir _0.04 O _3-σ As can be seen from fig. 2, the XRD pattern of the catalyst prepared by the invention can correspond to standard PDF card at different 2 theta angles, and has no obvious impurity peak, which indicates that no secondary phase is generated;

FIG. 3 shows La prepared in this example _0.6 Sr _0.4 Fe _0.96 Ir _0.04 O _3-σ SEM images of the catalyst, as can be obtained from fig. 3, the catalyst prepared by the present invention has the morphology of hollow nanofibers;

FIG. 4 shows La prepared in this example _0.6 Sr _0.4 Fe _0.96 Ir _0.04 O _3-σ The morphology of the hollow nanofibers of the catalyst prepared by the present invention can be more clearly seen from the TEM image of the catalyst in fig. 4;

FIG. 5 is a La prepared in example 1 of the present invention _0.6 Sr _0.4 Fe _0.96 Ir _0.04 O _3-σ The EDS spectrum of the catalyst, as can be seen from fig. 5, shows that La, sr, fe, ir and O elements are indeed present in the catalyst prepared by the present invention, which demonstrates that a-site Sr-doped B-site Ir-doped hollow nanofiber perovskite catalyst was successfully prepared by doping and electrospinning.

Example 2

Adding 0.9mmol of lanthanum nitrate hexahydrate, 0.6mmol of strontium nitrate, 1.47mmol of ferric nitrate nonahydrate and 0.03mmol of iridium trichloride into a container filled with 10mL of N, N-dimethylformamide, stirring in a water bath at 40 ℃ for 20 minutes until the mixture is completely and uniformly dissolved, adding 1.42g of polyvinylpyrrolidone into the mixed solution, and stirring for 10 hours until the mixture is uniformly dissolved to obtain a viscous polymer solution;

transferring the viscous polymer solution into a plastic injector with the volume of 10mL for electrostatic spinning, wherein the parameters of the electrostatic spinning are as follows: the liquid injection speed is 0.4mL/h, the distance between the needle point and the collecting device is 18cm, the working voltage is 16kV, and after the electrostatic spinning treatment is completed, the release paper on the electrostatic spinning receiving device is taken down, and the release paper is separated to obtain a nanofiber polymer precursor;

calcining the nanofiber polymer precursor in a muffle furnace, and heating at a speed of 3 ℃/min in an air atmosphereAfter the temperature reaches 300 ℃, maintaining for 2 hours, then heating to 750 ℃ at the speed of 3 ℃/min, maintaining for 3 hours, naturally cooling to room temperature, and grinding to obtain La _0.6 Sr _0.4 Fe _0.96 Ir _0.04 O _3-σ A catalyst.

Example 3

Adding 0.9mmol of lanthanum nitrate hexahydrate, 0.6mmol of strontium nitrate, 1.41mmol of ferric nitrate nonahydrate and 0.09mmol of iridium trichloride into a container filled with 10mL of N, N-dimethylformamide, stirring in a water bath at 60 ℃ for 10 minutes until the mixture is completely and uniformly dissolved, adding 1.42g of polyvinylpyrrolidone into the mixed solution, and stirring for 10 hours until the mixture is uniformly dissolved to obtain a viscous polymer solution;

transferring the viscous polymer solution into a plastic injector with the volume of 10mL for electrostatic spinning, wherein the parameters of the electrostatic spinning are as follows: the liquid injection speed is 0.6mL/h, the distance between the needle point and the collecting device is 16cm, the working voltage is 16kV, and after the electrostatic spinning treatment is completed, the release paper on the electrostatic spinning receiving device is taken down, and the release paper is separated to obtain a nanofiber polymer precursor;

calcining nanofiber polymer precursor in a muffle furnace, heating to 260 ℃ at a speed of 2 ℃/min in an air atmosphere, maintaining for 2h, heating to 780 ℃ at a speed of 2 ℃/min, maintaining for 3h, naturally cooling to room temperature, and grinding to obtain La _0.6 Sr _0.4 Fe _0.96 Ir _0.04 O _3-σ A catalyst.

Example 4

Adding 0.9mmol of lanthanum nitrate hexahydrate, 0.6mmol of strontium nitrate, 1.38mmol of ferric nitrate nonahydrate and 0.12mmol of iridium trichloride into a container filled with 10mL of N, N-dimethylformamide, stirring in a water bath at 50 ℃ for 15 minutes until the mixture is completely and uniformly dissolved, adding 1.42g of polyvinylpyrrolidone into the mixed solution, and stirring for 10 hours until the mixture is uniformly dissolved to obtain a viscous polymer solution;

transferring the viscous polymer solution into a plastic injector with the volume of 10mL for electrostatic spinning, wherein the parameters of the electrostatic spinning are as follows: the liquid injection speed is 0.5mL/h, the distance between the needle point and the collecting device is 15cm, the working voltage is 18kV, and after the electrostatic spinning treatment is finished, the release paper on the electrostatic spinning receiving device is taken down, and the release paper is separated to obtain a nanofiber polymer precursor;

calcining nanofiber polymer precursor in a muffle furnace, heating to 280 ℃ at a speed of 4 ℃/min in an air atmosphere, maintaining for 2h, heating to 850 ℃ at a speed of 5 ℃/min, maintaining for 3h, naturally cooling to room temperature, and grinding to obtain La _0.6 Sr _0.4 Fe _0.96 Ir _0.04 O _3-σ A catalyst.

Comparative example 1

The iron-based perovskite catalyst is prepared by adopting a traditional method: 10mmol of lanthanum nitrate hexahydrate and 10mmol of ferric nitrate nonahydrate are weighed, dissolved in 100mL of deionized water, uniformly mixed, added with 40mmol of citric acid and 20mmol of ethylenediamine tetraacetic acid, stirred at room temperature until a uniform solution is formed, and then ammonia water is added dropwise into the solution until the pH value of the solution is equal to 8. Heating and stirring the solution in a water bath at 80 ℃, placing the obtained gel in a muffle furnace after gel substances appear, sintering for 5 hours at 250 ℃ to obtain a powder precursor, grinding the powder precursor, placing the powder precursor in the muffle furnace again, and sintering for 5 hours at 900 ℃ to obtain LaFeO ₃ Perovskite catalysts.

FIG. 6 shows the catalysts obtained in examples 1 to 4 of the present invention and LaFeO in comparative example 1 ₃ Performance test comparison graph of catalyst in catalytic oxygen evolution reaction. As can be seen from FIG. 6, la prepared according to the present invention _0.6 Sr _0.4 Fe _0.96 Ir _0.04 O _3-σ The oxygen evolution capacity of the catalyst is obviously better than that of LaFeO prepared by the traditional method ₃ Perovskite catalysts, in particular: at a current density of 10 mA.cm ^-2 La at time La _0.6 Sr _0.4 Fe _0.96 Ir _0.04 O _3-σ The potential of the catalyst is obviously less than LaFeO ₃ The perovskite catalyst has a potential and a current density significantly higher than that of LaFeO ₃ The perovskite catalyst shows that the morphology of the A-site Sr doped B-site Ir doped hollow nanofiber can obviously improve the catalytic performance of the rare earth iron-based perovskite oxide, so that the capability of catalyzing oxygen evolution reaction is improved.

FIG. 7 shows a process according to example 1 of the present inventionLa of the preparation _0.6 Sr _0.4 Fe _0.96 Ir _0.04 O _3-σ Catalyst and commercial catalyst RuO ₂ As can be seen from FIG. 7, the catalyst prepared according to the present invention has excellent oxygen evolution catalytic performance and performance approaching that of the commercial noble metal catalyst RuO in the comparison of performance tests of catalytic oxygen evolution reactions ₂ It can be stated that the technical proposal of the invention requires lower cost and catalyst RuO under the condition of consistent catalytic performance ₂ Compared with the catalyst, the cost performance of the catalyst is higher.

In the present specification, each embodiment is described in a progressive manner, and each embodiment is mainly described in a different point from other embodiments, and identical and similar parts between the embodiments are all enough to refer to each other.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. The preparation method of the AB-site co-doped perovskite nanofiber catalyst is characterized by comprising the following steps of:

2. The preparation method according to claim 1, wherein the mole volume ratio of lanthanum nitrate hexahydrate, strontium nitrate, ferric nitrate nonahydrate, iridium trichloride and N, N-dimethylformamide is 0.5-1.0 mmol:0.5 to 1.0mmol:1.38 to 1.47mmol:0.03 to 0.12mmol: 10-15 mL; the mass volume ratio of the polyvinylpyrrolidone to the N, N-dimethylformamide is 1-2 g: 10-15 mL.

3. The method according to claim 2, wherein the temperature of the mixing in the step S1 is 40 to 60 ℃ and the mixing time is 8 to 15 hours.

4. A method according to any one of claims 1 to 3, wherein the parameters of the electrospinning process are: the liquid injection speed is 0.4-0.6 mL/h, the distance between the needle tip and the collecting device is 15-18 cm, and the working voltage is 15-18 kV.

5. The method according to claim 4, wherein the calcination treatment is divided into two stages, the temperature of the first stage is 200 to 300 ℃, and the heat preservation time of the first stage is 1.5 to 2.5 hours; the temperature of the second stage is 750-850 ℃, and the heat preservation time of the second stage is 2.5-3.5 h.

6. The method according to claim 5, wherein the rate of temperature rise from room temperature to the temperature of the first stage is 1 to 5 ℃/min, and the rate of temperature rise from the temperature of the first stage to the temperature of the second stage is 1 to 5 ℃/min.

7. An AB site co-doped perovskite nanofiber catalyst prepared by the preparation method of any one of claims 1 to 6.

8. Use of the AB site co-doped perovskite nanofiber catalyst as defined in claim 7 in an oxygen evolution reaction.