Preparation method and application of self-supporting nitrogen-doped carbon nanotube confinement multi-scale metal hydrogen evolution reaction cathode catalyst

Abstract

The invention discloses a preparation method and application of a self-supporting nitrogen-doped carbon nanotube confinement multi-scale metal hydrogen evolution reaction cathode catalyst, the prepared catalyst uses a self-supporting carbon nanotube as a carrier, the confinement structure regulation of multiple metals is successfully realized, and especially under the support of the nitrogen-doped carbon nanotube, the metal hydrogen evolution reaction cathode catalyst can be used as a metal hydrogen evolution reaction cathode catalyst. The electron metal-carrier interaction (EMSI) of metal is obviously enhanced, and the activity and stability of the catalyst are improved. The metal particles with different sizes are effectively limited and dispersed in a multi-scale range through accurate regulation and control, so that the adsorption and conversion processes of a reaction intermediate are optimized; the catalyst has obvious performance in electro-catalysis, especially in hydrogen evolution reaction (HER), and can realize low overpotential, high quality activity and excellent stability in acidic and alkaline environments; by utilizing the confinement catalyst, high-efficiency hydrogen production by electrolyzing water can be realized under the condition of low platinum dosage, and the confinement catalyst has wide industrial application potential.

Description

Technical Field

[0001] The present invention relates to the field of new energy materials and electrochemical catalysis technology, and in particular to a method for preparing a self-supporting nitrogen-doped carbon nanotube confined multi-scale metal hydrogen evolution reaction cathode catalyst and its application. Background Art

[0002] As a clean and efficient energy conversion technology, hydrogen production by water electrolysis is of great significance in alleviating the energy crisis and reducing greenhouse gas emissions. However, the hydrogen evolution reaction in water electrolysis requires efficient catalysts to reduce the overpotential of the reaction and improve the energy conversion efficiency. Currently, precious metals (such as platinum) are widely considered to be the best catalysts for HER due to their excellent electrocatalytic properties, but their high cost and rarity limit large-scale industrial applications.

[0003] In recent years, researchers have been committed to developing catalyst design strategies that can improve the utilization rate of precious metals and reduce their usage. Among them, the confinement effect has become an important research direction. By limiting the size and distribution of metal active centers, the catalytic activity and stability of metals can be enhanced. For example, metal single-atom catalysts have significant advantages in improving metal utilization, but their single-atom centers may exhibit lower intrinsic activity due to the lack of synergy. In addition, although metal nanoparticles and cluster catalysts show stronger synergistic effects in reactions, the larger particle size may lead to a decrease in the utilization of active sites, limiting the further improvement of catalyst performance. In order to balance the activity and stability of the catalyst, by regulating the metal active centers to the distribution form of nanoclusters and confining them with suitable carriers, the adsorption energy of the reaction intermediates can be optimized and the overall performance of the catalyst can be improved.

[0004] In terms of carrier selection, high conductivity and chemical stability make carbon-based materials an excellent choice. In particular, nitrogen-doped carbon nanotubes have been widely used in the field of electrocatalysis due to their unique one-dimensional structure, high specific surface area and diverse defect sites. The defect sites introduced by nitrogen doping can not only enhance the binding of metal active centers, but also strengthen the electronic metal-support interaction (EMSI) by regulating the electronic structure, thereby improving the activity and stability of the catalyst. In addition, the self-supporting carbon nanotube carrier can provide good mechanical strength and electrical conductivity, avoiding the structural collapse of the catalyst under reaction conditions, thereby improving the durability of the catalyst.

[0005] Based on the above problems, the present invention proposes a preparation method and application of a self-supporting confined multi-scale metal catalyst based on nitrogen-doped carbon nanotubes. Summary of the invention

[0006] The purpose of the present invention is to solve the technical problems existing in the prior art and to provide a method for preparing a self-supporting nitrogen-doped carbon nanotube confined multi-scale metal hydrogen evolution reaction cathode catalyst and its application.

[0007] To achieve the above object, the technical solution provided by the present invention is: a method for preparing a self-supporting nitrogen-doped carbon nanotube confined multi-scale metal hydrogen evolution reaction cathode catalyst, the preparation method specifically comprising the following steps:

[0008] Step (1), solution preparation: dissolving nickel chloride and urea in water to form a uniform solution;

[0009] Step (2), precursor treatment: immersing the melamine sponge in the uniform solution prepared in step (1), stirring and dispersing, performing a hydrothermal reaction, and drying to obtain a precursor;

[0010] Step (3), high temperature calcination: calcining the precursor obtained in step (2) in a tube furnace to form nitrogen-doped carbon nanotubes;

[0011] Step (4), metal impregnation: immersing the nitrogen-doped carbon nanotube sample calcined in step (3) into a low-concentration metal solution, soaking and drying to obtain a sample;

[0012] Step (5), secondary calcination: calcining the sample in step (4) to form a catalyst loaded with metal clusters.

[0013] Preferably, the urea in step (1) is a nitrogen source, and the melamine sponge in step (2) is a carbon source.

[0014] Preferably, the stirring and dispersing time in step (2) is 30 to 90 minutes; and the hydrothermal reaction is: hydrothermal reaction at a temperature of 90 to 120° C. for 10 to 15 hours.

[0015] Preferably, the calcination temperature of the high temperature calcination in step (3) is 1000-1200°C, the annealing time is 60-90 minutes, the heating rate is 2-5°C / minute, and the annealing is carried out in an inert protective gas, which is at least one of argon and nitrogen.

[0016] Preferably, the nitrogen-doped carbon nanotubes formed during the high-temperature calcination process are formed by carbonization and induced growth of melamine sponge.

[0017] Preferably, the metal types in the metal solution in step (4) include but are not limited to platinum, palladium, ruthenium, iridium or their alloys.

[0018] Preferably, the calcination temperature of the secondary calcination in step (5) is 800-1000°C, the annealing time is 90-120 minutes, the heating rate is 2-5°C min, and the secondary calcination is carried out in at least one protective gas selected from argon and nitrogen.

[0019] Preferably, in step (5), the metal is uniformly dispersed on the surface of the carbon nanotube or inside the pores in the form of clusters or particles.

[0020] The present invention also discloses an application of a cathode catalyst prepared according to the above-mentioned method for preparing a cathode catalyst for a self-supporting nitrogen-doped carbon nanotube confined multi-scale metal hydrogen evolution reaction in the electrolysis of water hydrogen evolution reaction under acidic and alkaline conditions.

[0021] Beneficial effects of the present invention:

[0022] The self-supporting nitrogen-doped carbon nanotube confined multi-scale metal hydrogen evolution reaction cathode catalyst prepared in the present invention can effectively promote the key steps in the hydrogen evolution reaction process and efficiently realize the generation and release of hydrogen. In addition, the reasonable structural design of the catalyst, combined with the excellent conductivity and stability of the self-supporting nitrogen-doped carbon nanotubes, effectively improves the activity and durability of the catalyst, significantly reduces the overpotential and energy consumption in the process of water electrolysis; successfully solves the problems of low utilization rate and poor stability of metal active sites in traditional catalysts, and opens up a new method for efficient, stable and economical water electrolysis hydrogen production. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The drawings described herein are used to provide further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0024] Figure 1 This is a schematic diagram of the preparation process of the material described in Example 1 of the present invention;

[0025] Figure 2 The self-supporting nitrogen-doped carbon nanotube confined platinum cluster Pt NC / SEM image of Ni-CNTs / NCF composites;

[0026] Figure 3 The Pt described in Example 1 of the present invention NC TEM image of / Ni-CNTs / NCF composite;

[0027] Figure 4 The Pt described in Example 1 of the present invention NC / EDS image of Ni-CNTs / NCF composite material, showing the distribution of Pt and Ni elements;

[0028] Figure 5 The Pt described in Example 1 of the present invention NC X-ray photoelectron spectrum of / Ni-CNTs / NCF composites;

[0029] Figure 6 The Pt described in Example 1 of the present invention NC Raman spectrum of / Ni-CNTs / NCF composite material;

[0030] Figure 7 The Pt described in Example 1 of the present invention NC Linear sweep voltammetry curves (a) and Tafel curves (b) of hydrogen evolution reaction of Ni-CNTs / NCF composite materials and comparative samples in acidic electrolyte;

[0031] Figure 8 The Pt described in Example 1 of the present invention NC Linear sweep voltammetry curves (a) and Tafel curves (b) of hydrogen evolution reaction of / Ni-CNTs / NCF composite materials and comparative samples in alkaline electrolyte;

[0032] Fig. 9 The Pt described in Example 1 of the present invention NC / Ratio of overpotential and logarithm of current density of the catalyst between Ni-CNTs / NCF composite and comparative sample at different current densities in acidic electrolyte;

[0033] Fig.10 The Pt described in Example 1 of the present invention NC Arrhenius electrochemical performance diagram of / Ni-CNTs / NCF composites and comparative samples in alkaline electrolyte;

[0034] Fig.11 The Pt described in Example 1 of the present invention NC / The current-time variation curve of Ni-CNTs / NCF composite material in alkaline electrolyte;

[0035] Fig.12 The Pt described in Example 1 of the present invention NC Voltage-time variation curve of / Ni-CNTs / NCF composite material applied in proton exchange membrane (PEM) electrolyzer. DETAILED DESCRIPTION

[0036] This section will describe in detail the specific embodiments of the present invention. The preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the accompanying drawings is to supplement the description of the text part of the specification with graphics, so that people can intuitively and vividly understand each technical feature and the overall technical solution of the present invention, but it cannot be understood as a limitation on the scope of protection of the present invention.

[0037] Reference Figure 1-Figure 12 , a preferred embodiment of the present invention, a method for preparing a self-supporting nitrogen-doped carbon nanotube confined multi-scale metal hydrogen evolution reaction cathode catalyst, the preparation method specifically comprises the following steps:

[0038] Step (1), solution preparation: dissolving nickel chloride and urea in water to form a uniform solution;

[0039] Step (2), precursor treatment: immersing the melamine sponge in the uniform solution prepared in step (1), stirring and dispersing, performing a hydrothermal reaction, and drying to obtain a precursor;

[0040] Step (3), high temperature calcination: calcining the precursor obtained in step (2) in a tube furnace to form nitrogen-doped carbon nanotubes;

[0041] Step (4), metal impregnation: immersing the nitrogen-doped carbon nanotube sample calcined in step (3) into a low-concentration metal solution, soaking and drying to obtain a sample;

[0042] Step (5), secondary calcination: calcining the sample in step (4) to form a catalyst loaded with metal clusters.

[0043] Furthermore, the urea in step (1) is a nitrogen source, and the melamine sponge in step (2) is a carbon source.

[0044] Furthermore, the stirring and dispersing time in step (2) is 30 to 90 minutes; and the hydrothermal reaction is: hydrothermal reaction at a temperature of 90 to 120° C. for 10 to 15 hours.

[0045] Furthermore, the calcination temperature of the high temperature calcination in step (3) is 1000-1200°C, the annealing time is 60-90 minutes, the heating rate is 2-5°C / minute, and the annealing is carried out in an inert protective gas, which is at least one of argon and nitrogen.

[0046] Furthermore, the nitrogen-doped carbon nanotubes formed during the high-temperature calcination process are formed by carbonization and induced growth of melamine sponge.

[0047] Furthermore, the metal types in the metal solution in step (4) include but are not limited to platinum, palladium, ruthenium, iridium or their alloys.

[0048] Specifically, the metal loading process uses a low concentration metal precursor (such as chloroplatinic acid, palladium chloride or ruthenium chloride) solution for impregnation, and the metal-loaded sample is subjected to secondary calcination to achieve multi-scale regulation of metal clusters (2-5nm) and particles (15-20nm).

[0049] Furthermore, in step (5), the calcination temperature of the secondary calcination is 800-1000° C., the annealing time is 90-120 minutes, the heating rate is 2-5° C. minutes, and the secondary calcination is carried out in at least one protective gas selected from argon and nitrogen.

[0050] Furthermore, in step (5), the metal is uniformly dispersed on the surface of the carbon nanotube or inside the pores in the form of clusters or particles.

[0051] Specifically, under a microscope, it appears as a multi-scale distribution of metals loaded on carbon nanotubes, with metal clusters and particles evenly distributed on the inner wall and outer surface of the carbon nanotubes.

[0052] The present invention also discloses an application of a cathode catalyst prepared according to the above-mentioned method for preparing a cathode catalyst for a self-supporting nitrogen-doped carbon nanotube confined multi-scale metal hydrogen evolution reaction in the electrolysis of water hydrogen evolution reaction under acidic and alkaline conditions.

[0053] The catalyst prepared by the present invention uses nitrogen-doped carbon nanotubes as carriers, combined with the confinement effect of metal clusters and metal particles, to achieve multi-scale structural regulation of metal active centers. The electronic metal-carrier interaction of the metal is significantly enhanced with the support of nitrogen-doped carbon nanotubes, thereby optimizing the catalytic performance, especially the activity and stability in the hydrogen evolution reaction.

[0054] The catalyst prepared in the present invention is not only suitable for the loading of Pt metal, but can also be widely used in other metal systems such as Pd, Ru, and Ir.

[0055] The present invention can effectively reduce the usage of precious metals, and exhibits low overpotential, high quality activity and good stability in acidic and alkaline water electrolysis environments, and is suitable for clean energy technologies such as water electrolysis to produce hydrogen.

[0056] Preferably, the reaction system is suitable for hydrogen evolution reaction by water electrolysis under acidic (such as 0.5M H2SO4) and alkaline (such as 1M KOH) conditions.

[0057] Embodiment 1

[0058] The present invention provides a self-supporting nitrogen-doped carbon nanotube-loaded platinum cluster composite material Pt based on nickel catalysis NC The preparation method of / Ni-CNTs / NCF specifically comprises the following steps:

[0059] 1) Select commercial melamine sponge and cut it into small pieces (5 cm × 3 cm × 2 cm), dissolve nickel chloride (NiCl2·6H2O) and urea in 300-400 mL of deionized water to prepare a 0.1 mol / L aqueous solution;

[0060] 2) Place the sponge in the above aqueous solution and stir for 30 minutes, then place in an oven and heat at 95°C for 12 hours; take out and place in an oven and dry at 60°C;

[0061] 3) The dried sample was placed in a tubular furnace and calcined under the following conditions under argon atmosphere: temperature 1000°C, heating rate 2°C / min, and insulation for 1 hour; after cooling to room temperature, the black product was taken out, washed thoroughly with deionized water and ethanol, and dried to obtain a nickel-catalyzed three-dimensional self-supporting carbon skeleton nitrogen-doped carbon support (Ni-CNTs / NCF).

[0062] 4) The obtained Ni-CNTs / NCF sample was immersed in 5 mL of chloroplatinic acid aqueous solution (3.86 mmol·L-1) at room temperature for 4 hours;

[0063] 5) After the sample is dried, it is kept at 800°C for 2 hours in an argon atmosphere at a heating rate of 2°C / min to complete the reduction and loading of the platinum clusters to obtain a self-supporting nitrogen-doped carbon nanotube confined platinum cluster composite material Pt NC / Ni-CNTs / NCF.

[0064] like Figure 1 The figure shows a self-supporting nitrogen-doped carbon nanotube confined platinum cluster composite material Pt NC Schematic diagram of the preparation of / Ni-CNTs / NCF.

[0065] Example 2 Material Characterization

[0066] 1) If Figure 2 The SEM image shows the overall morphology of the material and the distribution of carbon nanotubes; Figure 3 TEM was used to further observe the size and distribution of Pt clusters, and the average size of Pt clusters was determined to be 2 to 5 nm; Figure 4 The EDS images show the uniform distribution of Pt and Ni in the material and the tip growth mechanism of carbon nanotubes;

[0067] 2) If Figure 5 As shown, the electronic structure of Pt and the electronic metal-support interaction are revealed by XPS; Figure 6 The degree of graphitization and defects of the material are revealed.

[0068] Example 3 Electrochemical Performance Test

[0069] The preparation method of the electrode material in the present invention is as follows: 3 mg of the catalyst is ultrasonically dissolved in a mixed solution of 490 μL of isopropanol, 490 μL of deionized water and 20 μL of naphthol, and ultrasonicated for at least 30 minutes to obtain a uniformly mixed dispersion; then 10 μL is coated on the surface of a glassy carbon electrode, and after drying, it is a working electrode, a three-electrode system is used, and the electrolyte is 0.5 mol / L H2SO4 solution or 1.0 mol / L KOH solution.

[0070] like Figure 7-11 As shown, Pt NC / Ni-CNTs / NCF exhibits excellent HER activity and fast reaction kinetics under both acidic and alkaline conditions. Through electrochemical tests at different temperatures, Arrhenius curves were drawn and the apparent activation energy of HER was calculated. NC / Ni-CNTs / NCF has the smallest activation energy; long-term stability tests show that the sample current decays less, showing good electrochemical stability; Fig.12 As shown, Pt NC The / Ni-CNTs / NCF electrode was applied in a proton exchange membrane electrolyzer, and it showed 200 hours of hydrolysis stability. The present invention successfully achieved high-efficiency hydrogen evolution performance by designing a self-supporting nitrogen-doped carbon nanotube confined platinum cluster composite material. In acidic, alkaline and actual PEM electrolyzer tests, the material showed excellent catalytic activity and stability, and has important application prospects.

[0071] Under the premise that no conflict occurs, those skilled in the art may freely combine and superimpose the above-mentioned additional technical features.

[0072] The above description is only a preferred implementation mode of the present invention. Any technical solution that achieves the purpose of the present invention by substantially the same means belongs to the protection scope of the present invention.

Claims

1. A method for preparing a self-supporting nitrogen-doped carbon nanotube confined multi-scale metal hydrogen evolution reaction cathode catalyst, characterized in that: The preparation method specifically comprises the following steps: Step (1), solution preparation: dissolving nickel chloride and urea in water to form a uniform solution; Step (2), precursor treatment: immersing the melamine sponge in the uniform solution prepared in step (1), stirring and dispersing, performing a hydrothermal reaction, and drying to obtain a precursor; Step (3), high temperature calcination: calcining the precursor obtained in step (2) in a tube furnace to form nitrogen-doped carbon nanotubes; Step (4), metal impregnation: immersing the nitrogen-doped carbon nanotube sample calcined in step (3) into a low-concentration metal solution, soaking and drying to obtain a sample; Step (5), secondary calcination: calcining the sample in step (4) to form a catalyst loaded with metal clusters.

2. The method for preparing a self-supporting nitrogen-doped carbon nanotube confined multi-scale metal hydrogen evolution reaction cathode catalyst according to claim 1, characterized in that: The urea in step (1) is a nitrogen source, and the melamine sponge in step (2) is a carbon source.

3. The method for preparing a self-supporting nitrogen-doped carbon nanotube confined multi-scale metal hydrogen evolution reaction cathode catalyst according to claim 1, characterized in that: The stirring and dispersing time in step (2) is 30 to 90 minutes; the hydrothermal reaction is: hydrothermal reaction at a temperature of 90 to 120° C. for 10 to 15 hours.

4. The method for preparing a self-supporting nitrogen-doped carbon nanotube confined multi-scale metal hydrogen evolution reaction cathode catalyst according to claim 1, characterized in that: The calcination temperature of the high-temperature calcination in step (3) is 1000-1200°C, the annealing time is 60-90 minutes, the heating rate is 2-5°C / minute, and the annealing is carried out in an inert protective gas, which is at least one of argon and nitrogen.

5. The method for preparing a self-supporting nitrogen-doped carbon nanotube confined multi-scale metal hydrogen evolution reaction cathode catalyst according to claim 1, characterized in that: The nitrogen-doped carbon nanotubes formed during the high-temperature calcination process are carbonized and induced to grow from melamine sponge.

6. The method for preparing a self-supporting nitrogen-doped carbon nanotube confined multi-scale metal hydrogen evolution reaction cathode catalyst according to claim 1, characterized in that: The metal types in the metal solution in step (4) include but are not limited to platinum, palladium, ruthenium, iridium or their alloys.

7. The method for preparing a self-supporting nitrogen-doped carbon nanotube confined multi-scale metal hydrogen evolution reaction cathode catalyst according to claim 1, characterized in that: The calcination temperature of the secondary calcination in step (5) is 800-1000° C., the annealing time is 90-120 minutes, the heating rate is 2-5° C. minutes, and the secondary calcination is carried out in at least one protective gas selected from argon and nitrogen.

8. The method for preparing a self-supporting nitrogen-doped carbon nanotube confined multi-scale metal hydrogen evolution reaction cathode catalyst according to claim 1, characterized in that: In step (5), the metal is uniformly dispersed on the surface of the carbon nanotube or inside the pores in the form of clusters or particles.

9. Use of a cathode catalyst prepared according to the method for preparing a self-supporting nitrogen-doped carbon nanotube confined multi-scale metal cathode catalyst for hydrogen evolution reaction according to any one of claims 1 to 8 in the electrolysis of water for hydrogen evolution reaction under acidic and alkaline conditions.

Images