CN114883585A

CN114883585A - Multifunctional non-noble metal nitrogen-doped carbon catalyst and preparation method and application thereof

Info

Publication number: CN114883585A
Application number: CN202210426382.9A
Authority: CN
Inventors: 李秀峰; 刘建胜; 刘向
Original assignee: Tongji University
Current assignee: Tongji University
Priority date: 2022-04-21
Filing date: 2022-04-21
Publication date: 2022-08-09

Abstract

The invention belongs to the technical field of electrochemical energy, and provides a multifunctional non-noble metal nitrogen-doped carbon catalyst, and a preparation method and application thereof. The material is applied to fuel cells, metal batteries and electrolytic water energy devices, and shows good electrochemical performance and excellent stability. The preparation method is simple, reduces the cost of the catalyst to a great extent, can be synthesized in batch, and is beneficial to popularization and application.

Description

Multifunctional non-noble metal nitrogen-doped carbon catalyst and preparation method and application thereof

Technical Field

The invention belongs to the technical field of electrochemical energy, and particularly relates to a functional non-noble metal nitrogen-doped carbon catalyst, and a preparation method and application thereof.

Background

The increasing demand for renewable and clean energy has prompted the worldwide search for environmentally friendly, economically sustainable and efficient energy technologies. The Hydrogen Evolution Reaction (HER) is an important hydrogen production kinetic process with the potential to replace fossil fuels. Also, efficient Oxygen Reduction Reaction (ORR) and Oxygen Evolution Reaction (OER) are of paramount importance in renewable energy platforms, especially for fuel cells and rechargeable batteries, and at present, the development of a practical, economical, high stability, high performance electrocatalyst remains an important task. Platinum and its derivatives are by far the most effective electrocatalysts for ORR and HER. However, such noble metal materials are costly and have limited resources. In spite of the challenges faced, the development of efficient, durable, multifunctional, non-noble metal electrocatalysts is urgently needed for sustainable large-scale application to clean energy devices.

Recent studies have shown that high catalytic activity of transition metal oxides is a promising alternative to noble metal catalysts. However, their structure is unstable and poor in conductivity, reducing their catalytic activity and durability, which hinders commercialization of rechargeable batteries and water-splitting devices. Transition metal selenides have recently been considered as novel catalysts for energy storage and conversion systems due to their numerous nanoporous networks, huge electrical conductivity and excellent catalytic activity, however, nickel selenide has low durability, which limits its large-scale use. Therefore, it is desirable to search for a simple and versatile method for producing non-noble metal materials with unique structures and high specific surface area electrocatalytic properties.

Disclosure of Invention

Based on the current situation that the prior art lacks non-noble metal materials with unique structures and high specific surface area electrocatalysis characteristics, the invention provides a multifunctional non-noble metal nitrogen-doped carbon catalyst and a preparation method and application thereof.

The purpose of the invention can be realized by the following technical scheme:

the invention firstly provides a preparation method of a multifunctional non-noble metal nitrogen-doped carbon catalyst, which comprises the following steps:

step S1: dissolving dimethyl imidazole in a methanol solution to obtain a solution A, dissolving cobalt nitrate hexahydrate in the methanol solution to obtain a solution B, slowly injecting the solution A into the solution B under ultrasound, stirring to obtain a mixed solution, sealing the mixed solution for reaction, centrifuging the obtained reactant, washing, and drying the obtained precipitate;

step S2: and carbonizing the dried product in the step S1 at high temperature in an inert gas atmosphere to obtain a carbonized substance, namely the multifunctional non-noble metal nitrogen-doped carbon catalyst, which is recorded as Co & NOC.

In the preparation method of the multifunctional non-noble metal nitrogen-doped carbon catalyst provided by the invention, the following scheme can be further adopted: wherein the cobalt nitrate hexahydrate is dissolved in a B solution obtained by a methanol solution, and the concentration of the cobalt nitrate hexahydrate is 1 g-3 g/80 mL; the dimethyl imidazole is dissolved in a solution A obtained by a methanol solution, and the concentration of the dimethyl imidazole is 2.5g/50 mL.

In the preparation method of the multifunctional non-noble metal nitrogen-doped carbon catalyst provided by the invention, the following scheme can be further adopted: wherein, the volume proportion relation of the solution A injected into the solution B is as follows: 50ml LA solution: 80mL of B solution.

In the preparation method of the multifunctional non-noble metal nitrogen-doped carbon catalyst provided by the invention, the following scheme can be further adopted: the solution A is poured into the solution B, and the solution A is dripped off in 25min, and the solution A is dripped into the solution B in an average volume of 2mL per minute.

The process of injecting the solution A into the solution B is slow, the speed of injecting the solution A into the solution B influences the size of reactant particles, the faster the injection speed is, the larger the reactant particles are, the smaller the specific surface area of large-particle materials is, and further the number of active sites is reduced. Therefore, the slower the process of injecting the a solution into the B solution, the better.

In the preparation method of the multifunctional non-noble metal nitrogen-doped carbon catalyst provided by the invention, the following scheme can be further adopted: in step S1, the stirring conditions are: stirring at room temperature for 30 min.

In the preparation method of the multifunctional non-noble metal nitrogen-doped carbon catalyst provided by the invention, the following scheme can be further adopted: in step S1, the reaction temperature is 25 ℃ and the reaction time is 12-24 h.

In the preparation method of the multifunctional non-noble metal nitrogen-doped carbon catalyst provided by the invention, the following scheme can be further adopted: in step S1, the solution required for washing is one or more of methanol and ethanol, and the washing with alcohol has the following functions: the unreacted organics were washed away.

In the preparation method of the multifunctional non-noble metal nitrogen-doped carbon catalyst provided by the invention, the following scheme can be further adopted: in step S1, the drying condition is vacuum drying or freeze drying, the temperature of the vacuum drying is 60-80 ℃, and the drying time is 12-24 h; the temperature of freeze drying is-47 ℃ or below, and the drying time is 12-24 h.

In the preparation method of the multifunctional non-noble metal nitrogen-doped carbon catalyst provided by the invention, the following scheme can be further adopted: in step S2, the inert gas is one of nitrogen and argon.

In the preparation method of the multifunctional non-noble metal nitrogen-doped carbon catalyst provided by the invention, the following scheme can be further adopted: in step S2, the conditions for high-temperature carbonization are: the carbonization temperature is 750-900 ℃, and the carbonization time is 1-4 h.

In the preparation method of the multifunctional non-noble metal nitrogen-doped carbon catalyst provided by the invention, the following scheme can be further adopted: in step S2, the carbonized material is further subjected to a polishing treatment in such a manner that the material is sufficiently polished with a mortar.

The invention also provides the multifunctional non-noble metal nitrogen-doped carbon catalyst prepared based on the preparation method, and the multifunctional non-noble metal nitrogen-doped carbon catalyst is a conductive catalyst.

The invention also provides application of the multifunctional non-noble metal nitrogen-doped carbon catalyst prepared by the preparation method in a fuel cell.

In the application of the multifunctional non-noble metal nitrogen-doped carbon catalyst provided by the invention, the following scheme can be further adopted: wherein the multifunctional non-noble metal nitrogen-doped carbon catalyst is used as a cathode catalyst of the fuel cell.

In the application of the multifunctional non-noble metal nitrogen-doped carbon catalyst provided by the invention, the following scheme can be further adopted: the application steps are as follows:

perfluorosulfonic acid in a mass ratio: dispersion solvent ═ 1: 30, preparing a dispersing agent by using perfluorinated sulfonic acid and a dispersing solvent, mixing the dispersing agent with the multifunctional non-noble metal nitrogen-doped carbon catalyst, and ultrasonically mixing and dispersing on the platinum-carbon electrode.

In the application of the multifunctional non-noble metal nitrogen-doped carbon catalyst provided by the invention, the following scheme can be further adopted: wherein the dosage relationship between the dispersant and the multifunctional non-noble metal nitrogen-doped carbon catalyst is 1 mL: 2mg of the active ingredient.

In the application of the multifunctional non-noble metal nitrogen-doped carbon catalyst provided by the invention, the following scheme can be further adopted: wherein the dispersant is isopropanol or ethanol.

The catalyst provided by the invention has the advantages of simple preparation method and mild preparation conditions (room temperature synthesis), the prepared catalyst has the advantages of multifunctional application, good stability and excellent methanol resistance, and the scheme provided by the invention not only provides a general strategy for developing advanced carbon materials with multifunctional application and non-noble metal nitrogen doping, but also provides useful guidance for designing and developing non-noble metal nitrogen-doped carbon catalysts for various energy-related electrocatalytic reactions.

Compared with the prior art, the technical effects of the invention are mainly embodied in the following aspects:

the multifunctional non-noble metal nitrogen-doped carbon catalyst provided by the invention is prepared by taking dimethyl imidazole as an organic ligand and cobalt nitrate hexahydrate as a metal source and synthesizing a multifunctional non-noble metal nitrogen-doped carbon catalyst Co & NOC material by an in-situ polymerization method at room temperature, and the prepared multifunctional non-noble metal nitrogen-doped carbon Co & NOC catalyst has abundant micro-mesopores by adopting proper raw material dosage and reaction conditions.

In addition, it has been demonstrated that nitrogen-doped carbon materials can achieve higher electrical conductivity, thereby limiting resistive losses and enhancing electrocatalytic activity during electrocatalytic processes. The key point of the material design is to optimize the electronic structure of the carbon carrier, and the carbon doping of nitrogen enhances charge transfer and improves the surface wettability so as to improve the catalytic performance.

The prepared non-noble metal nitrogen-doped carbon catalyst is respectively applied to a fuel cell, a metal air cell and an electrolytic water device, so that the prepared multifunctional non-noble metal nitrogen-doped carbon catalyst has good electrochemical performance, and through electrochemical tests, the oxygen reduction (ORR) half slope point of the electrode in a 0.1M KOH solution is 0.83V, the voltage potential corresponding to the Oxygen Evolution Reaction (OER) delta E is 0.89V, and the voltage potential corresponding to the Hydrogen Evolution Reaction (HER) current density 10 is 0.35V. The stability of the catalyst in alkaline solution is higher than that of commercial platinum carbon, and the catalyst does not contain any noble metal, so that the cost of the fuel cell cathode catalyst is greatly reduced while high activity and stability are ensured.

Therefore, the multifunctional non-noble metal nitrogen-doped carbon catalyst provided by the invention has the advantages of simple preparation method, low cost, high stability, large-scale synthesis and contribution to popularization and use.

Drawings

FIG. 1 is a schematic diagram of a process for preparing a catalyst according to the present invention;

FIG. 2 is a scanning electron micrograph of electrochemical linear scan images of catalysts prepared in examples 1, 2 and 3 of the present invention;

FIG. 3 is an electrochemical linear scan of the catalyst in 0.1M HClO4 solution in examples 1 and 2 of the present invention;

FIG. 4 is a linear electrochemical scan of the catalyst in 0.1M KOH solution in examples 2, 3, 4, and 5 of the present invention;

FIG. 5 is a diagram of electrochemical linear scans of examples 2, 3, 4, 5 of the present invention in 0.1M KOH solution;

FIG. 6 is a linear electrochemical scan of examples 2, 3, and 4 in 0.1M KOH solution.

Detailed Description

In order to make the technical means, the creation characteristics, the achievement purposes and the effects of the invention easy to understand, the preparation and the application of the multifunctional non-noble metal nitrogen-doped carbon catalyst of the invention are specifically described below with reference to the embodiment and the accompanying drawings.

The starting materials used in the present invention are commercially available or commonly used in the art, unless otherwise specified, and the methods in the following examples are conventional in the art, unless otherwise specified.

Example 1

In this example, the nitrogen source was dimethylimidazole, the metal source was cobalt nitrate hexahydrate, and the obtained non-noble metal nitrogen-doped carbon nanomaterial was Co & NOC. The preparation process refers to fig. 1.

2.5g of dimethylimidazole is dissolved in 50mL of methanol solution (solution A), 1.0g of cobalt nitrate hexahydrate is dissolved in 80mL of methanol solution (solution B), the solution A is slowly injected into the solution B under ultrasound, and the solution A is dripped off in 25min, and 2mL of solution A is dripped off per minute on average. Stirring at room temperature for 30min, sealing the mixed solution, reacting at room temperature for 12h, centrifuging the obtained reactant with methanol or ethanol, washing until the supernatant is transparent, and freeze-drying the obtained precipitate for 12 h; the dried product was carbonized at 750 ℃ in a nitrogen atmosphere to obtain a carbonized substance, and the carbonized substance was sufficiently ground with a mortar to obtain a conductive catalyst (Co & NOC-750).

Example 2

In this example, the nitrogen source was dimethylimidazole, the metal source was cobalt nitrate hexahydrate, and the obtained non-noble metal nitrogen-doped carbon nanomaterial was Co & NOC.

2.5g of dimethylimidazole is dissolved in 50mL of methanol solution (solution A), 1.0g of cobalt nitrate hexahydrate is dissolved in 80mL of methanol solution (solution B), the solution A is slowly injected into the solution B under ultrasound, the solution A is dripped off in 5min, and 2mL of solution A is dripped per minute on average. Stirring at room temperature for 30min, sealing the mixed solution, reacting at room temperature for 12h, centrifuging and washing the obtained reactant with methanol until the supernatant is transparent, and freeze-drying the obtained precipitate for 12 h; carbonizing the dried product at 750 ℃ in a nitrogen atmosphere, soaking the carbonized substance in a hydrofluoric acid solution for 4h (for removing redundant metal ions), centrifugally washing the acid-soaked material with deionized water, freeze-drying the washed material for 12h to obtain a dried substance, fully grinding the dried substance in a mortar, and grinding to obtain the conductive catalyst (Co & NOC-750).

Example 3

Dissolving 2.5g of dimethyl imidazole in 50mL of methanol solution (solution A), dissolving 1.0g of cobalt nitrate hexahydrate in 80mL of methanol solution (solution B), under the ultrasonic condition, slowly injecting the solution A into the solution B, stirring at room temperature for 30min, sealing the mixed solution, reacting at room temperature for 12h, centrifugally washing the obtained reactant with methanol until the supernatant is transparent, and freeze-drying the obtained precipitate for 12 h; carbonizing the dried product at 800 ℃ in a nitrogen atmosphere, soaking the carbonized substance in a hydrofluoric acid solution for 4h (for removing redundant metal ions), centrifugally washing the acid-soaked material with deionized water, freeze-drying the washed material for 12h to obtain a dried substance, fully grinding the dried substance in a mortar, and grinding to obtain the conductive catalyst (Co & NOC-800).

Example 4

Dissolving 2.5g of dimethyl imidazole in 50mL of methanol solution (solution A), dissolving 1.0g of cobalt nitrate hexahydrate in 80mL of methanol solution (solution B), under the ultrasonic condition, slowly injecting the solution A into the solution B, stirring at room temperature for 30min, sealing the mixed solution, reacting at room temperature for 12h, centrifugally washing the obtained reactant with methanol until the supernatant is transparent, and freeze-drying the obtained precipitate for 12 h; carbonizing the dried product at 850 ℃ in a nitrogen atmosphere, soaking the carbonized substance in a hydrofluoric acid solution for 4h (for removing redundant metal ions), centrifugally washing the acid-soaked material with deionized water, freeze-drying the washed material for 12h to obtain a dried substance, fully grinding the dried substance by using a mortar, and grinding to obtain the conductive catalyst (Co & NOC-850).

Example 5

Dissolving 2.5g of dimethyl imidazole in 50mL of methanol solution (solution A), dissolving 1.0g of cobalt nitrate hexahydrate in 80mL of methanol solution (solution B), under the ultrasonic condition, slowly injecting the solution A into the solution B, stirring at room temperature for 30min, sealing the mixed solution, reacting at room temperature for 12h, centrifugally washing the obtained reactant with methanol until the supernatant is transparent, and freeze-drying the obtained precipitate for 12 h; carbonizing the dried product at 900 ℃ in a nitrogen atmosphere, soaking the carbonized substance in a hydrofluoric acid solution for 4h (for removing redundant metal ions), centrifugally washing the acid-soaked material with deionized water, freeze-drying the washed material for 12h to obtain a dried substance, fully grinding the dried substance by using a mortar, and grinding to obtain the conductive catalyst (Co & NOC-900).

Test example 1

The Co & NOC-750 (ethanol washed or methanol washed) catalysts obtained in example 1 were individually subjected to scanning electron microscopy tests using linear scanning electrochemical testing, the results of which are shown in fig. 2.

Fig. 2 is a scanning electron micrograph of the catalyst prepared in example 1 of the present invention. Wherein the scan sizes are all 5 microns.

As shown in FIG. 2, in example 1, the washing with methanol gave a scanning electron micrograph of FIG. 2a, and the washing with ethanol gave a scanning electron micrograph of FIG. 2 b. The material obtained in the figure 2a is more uniform, the granularity is smaller, compared with the figure 2b, the material uniformity and the granularity are small, the material is more fully contacted with electrolyte, charge transmission is facilitated, the material has a larger specific surface area due to the smaller granularity, more active sites are exposed, and the electrocatalysis performance is improved. And (4) conclusion: when the material is centrifugally washed, the washing liquid influences the uniformity and granularity of the material, and the methanol washing effect for the experiment is better.

Test example 2

The Co & NOC-750 (not acid-washed) and Co & NOC-750 (acid-washed) catalysts obtained in examples 1 and 2, respectively, were electrochemically tested in 0.1M HClO4 solution using a linear scanning electrochemical test, and the results are shown in FIG. 3.

Fig. 3 is an electrochemical linear scan of the catalysts prepared in examples 1 and 2 of the present invention. Wherein, the abscissa is the voltage potential, unit: VRHE; the ordinate is the current density.

As shown in FIG. 3, the catalyst of example 2 was labeled Co & NOC-750-acid wash and had a half-slope potential of 0.74V. The catalyst in example 1 was labeled Co & NOC-750-no acid wash and had a half slope potential of 0.63V.

Table 1 shows the half slope potentials of the catalyst of example 1(Co & NOC-750-acid wash) and the catalyst of example 2(Co & NOC-750-acid wash):

table 1 table comparing potentials of example 1 and example 2

Name of Material	E _1/2 (V)	Test solution
			Co&NOC-750-Pickling	0.74	0.1M HClO ₄
Co&NOC-750 Pickling No acid	0.63	0.1M KOH HClO ₄

And (4) conclusion: as can be seen from Table 1, the Co & NOC-750-acid-washed catalyst had a half-slope potential of 0.74V, and the Co & NOC-750-acid-not-washed catalyst had a half-slope potential of 0.63V. It can be determined that the acid wash has an effect on the electrocatalytic properties of the material, since the acid wash washes out unstable and unreacted metal ions, exposing more active sites available for the material, and thus, the acid wash step is necessary.

Test example 3

The Co & NOC catalysts obtained in examples 2, 3, 4, 5 were subjected to electrochemical (oxygen reduction) tests in 0.1M KOH solution using linear scanning electrochemical tests, and the results are shown in fig. 4.

Fig. 4 is an electrochemical linear scan of the catalysts prepared in examples 2, 3, 4 and 5 of the present invention. Wherein, the abscissa is the voltage potential, unit: VRHE; the ordinate is the current density.

As shown in FIG. 4, the catalyst of example 2 was labeled Co & NOC-750 and had a hill-drop potential of 0.83V. The catalyst in example 3 was labeled Co & NOC-800 and had a hill potential of 0.81V. The catalyst of example 4 was labeled Co & NOC-850 and had a half-slope potential of 0.79V.

The catalyst of example 5, labeled Co & NOC-900, had a hill potential of 0.78V.

Table 2 shows the comparison of the hill potentials for the example 2(Co & NOC-750) catalyst, the example 3(Co & NOC-800) catalyst, the example 4(Co & NOC-850) catalyst and the example 5(Co & NOC-900) catalyst:

table 2 table comparing potentials of examples 2, 3 and 4 and example 5

Name of Material	E _1/2 (V)	Test solution
			Co&NOC-750	0.83	0.1M KOH
Co&NOC-800	0.81	0.1M KOH
			Co&NOC-850	0.79	0.1M KOH
Co&NOC-900	0.78	0.1M KOH

And (4) conclusion: as can be seen from Table 2, the half slope potential of the Co & NOC-750 catalyst at the carbonization temperature of 750 ℃ is 0.83V, the half slope potential of the Co & NOC-800 catalyst at the carbonization temperature of 800 ℃ is 0.81V, the half slope potential of the Co & NOC-850 catalyst at the carbonization temperature of 850 ℃ is 0.79V, and the half slope potential of the Co & NOC-900 catalyst at the carbonization temperature of 900 ℃ is 0.78V. Therefore, the catalyst with the carbonization temperature of 750 ℃ is more positive than the catalyst with the carbonization temperature of 800 ℃, the carbonization temperature of 850 ℃ and the carbonization temperature of 900 ℃ by the half slope potential of 0.05V. This is because higher carbonization temperatures cause the intrinsic octahedral structure of the material to collapse, thereby reducing the specific surface area exposure of the material, exposing fewer active sites. Therefore, the activity may be reduced by too high carbonization temperature, the carbonization temperature of 750 ℃ is most suitable for materials, and the low carbonization temperature is also beneficial to environmental protection.

Test example 4

The Co & NOC catalysts obtained in examples 2, 3, 4, 5 were subjected to electrochemical (oxygen reduction and oxygen evolution) tests in 0.1M KOH solution using linear scanning electrochemical tests, respectively, and the results are shown in fig. 5.

Fig. 5 is an electrochemical linear scan of the catalysts prepared in examples 2, 3, 4 and 5 of the present invention. Wherein, the abscissa is the voltage potential, unit: VRHE; the ordinate is the current density.

As shown in FIG. 5, the catalyst of example 2 was labeled Co & NOC-750 and had a Δ E of 0.89V. The catalyst of example 3, labeled Co & NOC-800, had a Δ E of 0.96V. The catalyst of example 4 was labeled Co & NOC-850 and had a Δ E of 0.93V. The catalyst of example 5, labeled Co & NOC-900, had a Δ E of 1.0V.

Table 3 shows the comparison of the hill potentials for the example 2(Co & NOC-750) catalyst, the example 3(Co & NOC-800) catalyst, the example 4(Co & NOC-850) catalyst and the example 5(Co & NOC-900) catalyst:

table 3 table of potential comparison of examples 2, 3, 4 and example 5

Name of Material	△E(V)	Test solution
			Co&NOC-750	0.89	0.1M KOH
Co&NOC-800	0.96	0.1M KOH
			Co&NOC-850	0.93	0.1M KOH
Co&NOC-900	1.0	0.1M KOH

And (4) conclusion: as can be seen from Table 3, the Delta E of the Co & NOC-750 catalyst having a carbonization temperature of 750 ℃ was 0.89V, the Delta E of the Co & NOC-800 catalyst having a carbonization temperature of 800 ℃ was 0.96V, the Delta E of the Co & NOC-850 catalyst having a carbonization temperature of 850 ℃ was 0.93V, and the Delta E of the Co & NOC-900 catalyst having a carbonization temperature of 900 ℃ was 1.0V. As is known, the smaller the Delta E, the better the bifunctional performance, so that the catalyst with the carbonization temperature of 750 ℃ is smaller than the catalytic Delta E with the carbonization temperature of 800 ℃, the carbonization temperature of 850 ℃ and the carbonization temperature of 900 ℃, and has better bifunctional performance.

Test example 5

Electrochemical (hydrogen evolution) tests were performed on the Co & NOC catalysts obtained in examples 2, 3, and 4, respectively, in 0.1M KOH solution using linear scanning electrochemical testing, and the results are shown in fig. 6.

Fig. 6 is an electrochemical linear scan of the catalysts prepared in examples 2, 3 and 4 of the present invention. Wherein, the abscissa is the voltage potential, unit: v _RHE (ii) a The ordinate is the current density.

As shown in fig. 6, the catalyst of example 2 is labeled Co & NOC-750, and the catalyst current density 10 corresponds to a voltage potential of 0.35V. The catalyst of example 3 is labeled as Co & NOC-800 and the catalyst current density 10 corresponds to a voltage potential of 0.38V. The catalyst of example 4 is labeled as Co & NOC-850 and the catalyst current density 10 corresponds to a voltage potential of 0.4V.

Table 4 shows the comparison of the catalysts of example 2(Co & NOC-750), example 3(Co & NOC-800) and example 4(Co & NOC-850):

table 4 table comparing potentials of examples 2 and 3 and example 4

Name of Material	E _J10 (V)	Test solution
			Co&NOC-750	0.35	0.1M KOH
Co&NOC-800	0.38	0.1M KOH
			Co&NOC-850	0.4	0.1M KOH

And (4) conclusion: as can be seen from Table 4, the voltage potential corresponding to the current density 10 of the Co & NOC-750 catalyst at the carbonization temperature of 750 ℃ is 0.35V, the voltage potential corresponding to the current density 10 of the Co & NOC-800 catalyst at the carbonization temperature of 800 ℃ is 0.38V, and the voltage potential corresponding to the current density 10 of the Co & NOC-850 catalyst at the carbonization temperature of 850 ℃ is 0.4V. It is known that a smaller voltage potential at a current density of 10 indicates more excellent hydrogen evolution performance, and therefore a catalyst having a carbonization temperature of 750 ℃ has a better hydrogen evolution performance than a catalyst having a carbonization temperature of 800 ℃ and a carbonization temperature of 850 ℃ and a voltage potential at a current density of 10.

Effects and effects of the embodiments

According to the preparation and application of the multifunctional non-noble metal nitrogen-doped carbon catalyst provided by the embodiment of the invention, 2.5g of dimethyl imidazole is dissolved in 50mL of methanol solution (solution A), 1.0g of cobalt nitrate hexahydrate is dissolved in 80mL of methanol solution (solution B), the solution A is slowly injected into the solution B under ultrasound, the mixed solution is sealed and reacted at room temperature after being stirred for 30min at room temperature, the reaction time is 12h, the obtained reactant is centrifugally washed by methanol until the supernatant is transparent, and the obtained precipitate is freeze-dried for 12 h; carbonizing the dried product in a nitrogen atmosphere, soaking the carbonized substance in a hydrofluoric acid solution for 4h (for removing redundant metal ions), centrifugally washing the acid-soaked material with deionized water, freeze-drying the washed material for 12h to obtain a dried substance, fully grinding the dried substance by using a mortar, and grinding to obtain the non-noble metal nitrogen-doped carbon catalyst (Co & NOC). When the carbonization temperature is 750 ℃, the multifunctional activity of the material is optimal under the acid washing condition.

In addition, the nitrogen doping of the carbon carrier can realize higher conductivity, thereby limiting resistance loss, enhancing electrocatalytic activity in the electrocatalytic process, optimizing the electronic structure of the carbon carrier, enhancing charge transfer and surface wettability, and further improving catalytic performance.

Therefore, the non-noble metal nitrogen-doped carbon catalyst provided by the invention has the advantages of simple preparation method, low cost, high stability, large-scale synthesis and contribution to popularization and use.

The embodiments described above are described to facilitate an understanding and use of the invention by those skilled in the art. It will be readily apparent to those skilled in the art that various modifications to these embodiments may be made, and the generic principles described herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present invention is not limited to the above embodiments, and those skilled in the art should make improvements and modifications within the scope of the present invention based on the disclosure of the present invention.

Claims

1. The preparation method of the multifunctional non-noble metal nitrogen-doped carbon catalyst is characterized by comprising the following steps of:

step S1: dissolving dimethyl imidazole in a methanol solution to obtain a solution A, dissolving cobalt nitrate hexahydrate in the methanol solution to obtain a solution B, injecting the solution A into the solution B under the ultrasonic condition, stirring to obtain a mixed solution, sealing the mixed solution for reaction, centrifuging the obtained reactant, washing, and drying the obtained precipitate;

step S2: and carbonizing the dried product in the step S1 at high temperature in an inert gas atmosphere to obtain a carbonized substance, namely the multifunctional non-noble metal nitrogen-doped carbon catalyst.

2. The method for preparing the multifunctional non-noble metal nitrogen-doped carbon catalyst according to claim 1, wherein the cobalt nitrate hexahydrate is dissolved in a B solution obtained from a methanol solution, and the concentration of the cobalt nitrate hexahydrate is 1 g-3 g/80 mL; the dimethyl imidazole is dissolved in a solution A obtained by a methanol solution, and the concentration of the dimethyl imidazole is 2.5g/50 mL;

the volume proportion relation of the solution A injected into the solution B is as follows: 50ml LA solution: 80mL of B solution.

3. The method for preparing the multifunctional non-noble metal nitrogen-doped carbon catalyst according to claim 1, wherein the solution A is injected into the solution B, and the solution A is dripped in 25min, wherein the average dripping amount is 2 mL/min.

4. The method for preparing the multifunctional non-noble metal nitrogen-doped carbon catalyst according to claim 1, wherein in the step S1, the reaction temperature is 25 ℃ and the reaction time is 12-24 h.

5. The method for preparing the multifunctional non-noble metal nitrogen-doped carbon catalyst according to claim 1, wherein in the step S1, the drying condition is vacuum drying or freeze drying, the temperature of the vacuum drying is 60 ℃ to 80 ℃, and the drying time is 12h to 24 h; the temperature of freeze drying is-47 ℃ or below, and the drying time is 12-24 h.

6. The method of claim 1, wherein in step S2, the conditions of the high temperature carbonization are as follows: the carbonization temperature is 750-900 ℃, and the carbonization time is 1-4 h.

7. The multifunctional non-noble metal nitrogen-doped carbon catalyst prepared by the preparation method of any one of claims 1 to 6.

8. Use of the multifunctional non-noble metal nitrogen-doped carbon catalyst of claim 7 in a fuel cell.

9. The use of the multifunctional non-noble metal nitrogen-doped carbon catalyst of claim 8 in a fuel cell, wherein the multifunctional non-noble metal nitrogen-doped carbon catalyst is used as a fuel cell cathode catalyst.

10. The use of the multifunctional non-noble metal nitrogen-doped carbon catalyst of claim 9 in a fuel cell, characterized by the following steps:

perfluorosulfonic acid in a mass ratio: dispersion solvent ═ 1: 30, preparing a dispersing agent by using perfluorinated sulfonic acid and a dispersing solvent, mixing the dispersing agent with a multifunctional non-noble metal nitrogen-doped carbon catalyst, and ultrasonically mixing and dispersing on a platinum carbon electrode;

wherein the dosage relationship between the dispersant and the multifunctional non-noble metal nitrogen-doped carbon catalyst is 1 mL: 2 mg.