Bimetallic carbon nanocomposite electrocatalytic material and its preparation method and application

Abstract

The present invention belongs to the field of electrode material technology, specifically a bimetallic carbon nanocomposite electrocatalytic material, its preparation method, and application. The present invention composites rhodium into porous carbon fibers, and then composites metallic nickel and carbon onto the surface of the porous carbon fibers to produce a bimetallic carbon nanocomposite electrocatalytic material. This composite electrode material overcomes the technical defects of rhodium, such as poor mechanical properties and limited use of carbon cloth, and can be used as a flexible catalytic electrode material in water electrolysis catalytic reactions. The bimetallic carbon nanocomposite electrocatalytic material of the present invention can be directly used for electrocatalytic hydrogen production without the need for complex pretreatment steps. Because it is in a carbon cloth state, it is self-supporting and flexible, and has a wider range of applications than the carbon cloth of the prior art.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrode materials, and in particular relates to a bimetallic carbon nanocomposite electrocatalytic material and a preparation method and application thereof. Background Art

[0002] Energy shortages and environmental pollution caused by the widespread use of fossil fuels have become two major challenges facing social development. Therefore, the development of new, pollution-free, clean energy sources is urgent. Hydrogen, with its extremely high energy density and efficient thermal conversion efficiency, has become a promising clean energy source. Electrochemical hydrogen production is key to many renewable energy systems, especially water splitting. In water splitting, flexible, self-supporting catalytic materials are ideal electrodes because they have a large surface area, which facilitates the timely removal of bubbles generated during the catalytic process, thus promoting the continued reaction.

[0003] The catalytic performance of nanomaterial-based electrocatalysts is affected by their dispersibility. For example, sheet materials like graphene, molybdenum sulfide, and tungsten sulfide are prone to wrinkling and forming aggregates, making the edge active sites less effective and limiting their application. To address this issue, researchers have experimented with using carbon fiber materials and metal foams, such as carbon cloth and carbon paper, and nickel foam, as substrates and electrode materials. These materials create stable three-dimensional nanostructures to improve catalytic efficiency. Furthermore, carbon fiber or nickel foam can be directly used as working electrodes in electrocatalysis, creating unique binder-free electrodes. Traditional electrochemical experiments for catalytic hydrogen evolution involve ultrasonically dispersing a mixture of the catalyst and Nafion, coating the mixture on a glassy carbon electrode, and then allowing the solution to dry naturally before testing. Compared to traditional methods, binder-free electrodes are simpler, more convenient, and less expensive, and the catalyst's three-dimensional structure allows it to fully utilize its performance. The direct use of materials like carbon cloth and carbon paper and metal foam as working electrodes for hydrogen evolution reactions has attracted widespread attention.

[0004] Although carbon cloth is flexible, it still requires complex pre-treatment steps before use and has certain limitations in practical applications. Therefore, preparing a self-supporting, flexible electrode material and directly using it as an electrocatalytic material for electrolytic water electrolysis to catalyze hydrogen production has become a new direction in the research of electrocatalysts. Summary of the Invention

[0005] In response to the above-mentioned technical deficiencies, the present invention provides a bimetallic carbon nanocomposite electrocatalytic material, a preparation method and an application thereof. The present invention compounds rhodium into porous carbon fibers, and then compounds metal nickel and carbon on the surface of the porous carbon fibers to prepare a bimetallic carbon nanocomposite electrocatalytic material. This composite electrode material overcomes the technical defects of poor mechanical properties of rhodium and the limitations of carbon cloth use, and can be used as a flexible catalytic electrode material and applied to water electrolysis catalytic reactions.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] The preparation method of the bimetallic carbon nanocomposite electrocatalytic material comprises the following steps:

[0008] (1) dissolving polyacrylonitrile and methyl methacrylate in N,N'-dimethylformamide to obtain a mixed solution; polyacrylonitrile is a conventional material for preparing carbon fibers, methyl methacrylate is a porogen, and the carbon fibers prepared using polyacrylonitrile and methyl methacrylate as raw materials are porous carbon fibers;

[0009] (2) adding rhodium trichloride monohydrate to the mixed solution of step (1) and continuously stirring for 8-12 hours to obtain a spinning solution, and electrostatically spinning the spinning solution to obtain electrospun nanofibers; blending rhodium trichloride monohydrate with the mixed solution and uniformly dispersing the mixture in the mixed solution, and making the rhodium trichloride monohydrate uniformly dispersed in the electrospun nanofibers after electrostatic spinning, and after carbonizing the electrospun nanofibers, rhodium can be uniformly dispersed in the carbon fibers, so that the carbon fibers limit the migration of rhodium, and at the same time, the carbon fibers have a certain space for the migration of rhodium, thereby overcoming the technical defect of poor mechanical properties of rhodium;

[0010] (3) The electrospun nanofibers of step (2) are first heated to 250-300°C and kept warm for 1-3 hours, and then heated to 550-600°C and kept warm for 1.5-2 hours; the staged heating not only realizes the step-by-step carbonization of polyacrylonitrile, but also realizes the oxidation of rhodium trichloride monohydrate, and the reaction formula is 4Rh·3H2O=Rh2O3+6HCl; then, under an inert atmosphere, the nanofibers are first calcined at 800-1000°C for 1-4 hours, and then calcined in an inert atmosphere to prepare carbon fibers, hydrogen is introduced, and the nanofibers are kept warm at 650-800°C for 2-3 hours, and Rh2O3 is reduced under hydrogen conditions to obtain Rh, and at this time, Rh is stably dispersed on the porous carbon fiber composite material to obtain rhodium@porous carbon fiber composite material;

[0011] (4) Weaving the rhodium@porous carbon fiber composite material of step (3) into carbon cloth, using the rhodium@porous carbon fiber composite material as carbon cloth, compared with the prior art of directly weaving carbon fibers into carbon cloth, the rhodium@porous carbon fiber composite material of the present invention has stronger catalytic performance;

[0012] (5) dispersing nickel nitrate in a carbon source solution to obtain a dispersion, then arranging carbon in the dispersion, and evaporating the solvent to obtain a carbon cloth gel material. The carbon source solution mainly forms a gel, and the nickel nitrate is stably dispersed in the gel. After evaporating the solvent, the carbon source provides carbon on the one hand, and on the other hand, the nickel nitrate is dispersed and attached to the surface of the carbon cloth;

[0013] (6) The carbon cloth gel material of step (5) is heated at 400-500°C for 2-3 hours, and then kept at 700-800°C for 1 hour under an inert atmosphere. At this time, the carbon source is carbonized and deposited on the surface of the carbon cloth. Hydrogen is then introduced and kept at 350-400°C for 3-5 hours. At this time, nickel nitrate is reduced to nickel nanoparticles by hydrogen and forms a bimetallic composite material with rhodium to obtain a bimetallic carbon nanocomposite electrocatalytic material. The bimetallic carbon nanocomposite electrocatalytic material can be directly used as a working electrode without the need for complex pretreatment operations.

[0014] Preferably, in step (1), the mass ratio of polyacrylonitrile to N,N'-dimethylformamide is 6-12:100; and the mass ratio of methyl methacrylate to polyacrylonitrile is 30-60:100.

[0015] Preferably, in step (2), the mass ratio of rhodium trichloride monohydrate to polyacrylonitrile is 0.3-0.5:1.

[0016] Preferably, the electrospinning conditions in step (2) are: using an electrospinning needle with an inner diameter of 0.3-1.2 mm, advancing at a voltage of 15-20 kV, a receiving distance of 14-20 cm, and an electrospinning propulsion speed of 0.5-2 mL / h.

[0017] Preferably, in step (5), the carbon source is selected from one of sodium alginate, potassium alginate, and lignin, the mass ratio of the carbon source to the nickel nitrate is 1:0.6-0.8, sodium alginate, potassium alginate, and lignin can all form gels, and the mass fraction of the carbon source in the carbon source solution is 1-5%.

[0018] The invention also protects the bimetallic carbon nanocomposite electrocatalytic material prepared by the preparation method.

[0019] The present invention also protects the application of the bimetallic carbon nanocomposite electrocatalytic material in the preparation of water electrolysis catalytic electrodes.

[0020] Preferably, the method for the electrolytic water catalytic reaction is: using an Ag / AgCl electrode containing saturated potassium chloride as a reference electrode, a platinum wire electrode as a counter electrode, and a bimetallic carbon nanocomposite electrocatalytic material as a working electrode to form a three-electrode system, connected to an electrochemical detection device, and using a sulfuric acid solution with a pH of 0.2-1 as an electrolyte to perform water electrolysis operation.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. In the electrochemical hydrogen evolution process, Pt and Pt-based materials are the best known hydrogen production materials. However, the scarcity of Pt limits its further development, so finding an alternative catalytic material is particularly critical. In recent years, reports on Rh-based materials have also shown that Rh has excellent HER catalytic performance and stability comparable to Pt. However, as an inorganic material, Rh has poor mechanical properties, which further limits its development in electrocatalytic water splitting. Based on this, the present application blends rhodium trichloride monohydrate with polyacrylonitrile to prepare electrospun fibers, and then carbonizes the electrospun fibers. At this time, the rhodium is evenly dispersed in the carbon fibers, overcoming the technical defects of poor mechanical properties of Rh. At the same time, the catalytic effect is improved by using Rh.

[0023] 2. The bimetallic carbon nanocomposite electrocatalytic material of the present invention can be directly used for electrocatalytic hydrogen production without the need for complex pre-treatment steps. Moreover, since it is in a carbon cloth state, it is self-supporting and flexible, and its application range is wider than that of the carbon cloth in the prior art.

[0024] 3. The bimetallic material of the present invention simultaneously introduces nickel, a late transition metal element with a large number of empty d orbitals, and Rh, whose HER catalytic performance is comparable to that of Pt, to fundamentally and effectively improve the catalytic performance of carbon fiber. At the same time, the outer layer is more corrosion-resistant under the coating of carbon atoms, thereby improving the service life of the electrocatalytic material. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 XRD comparison diagram of Rh and the bimetallic carbon nanocomposite electrocatalytic material prepared in Example 2;

[0026] Figure 2 At a current density of 10 mA cm -2 and 20mAcm -2 IT test curve of the bimetallic carbon nanocomposite electrocatalytic material of Example 2 below;

[0027] Figure 3 This is a comparison diagram of the LSV curves of the bimetallic carbon nanocomposite electrocatalytic material of Example 2 before and after 5000 cyclic voltammetry scans;

[0028] Figure 4 This is a comparison chart of the polarization curves of water splitting of the bimetallic carbon nanocomposite electrocatalytic material / / RuO2 and Pt / C / / RuO2 in Example 2. DETAILED DESCRIPTION

[0029] The specific embodiments of the present invention are described in detail below, but it should be understood that the scope of protection of the present invention is not limited by the specific embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. The experimental methods described in the embodiments of the present invention are all conventional methods unless otherwise specified.

[0030] Example 1

[0031] The preparation method of the bimetallic carbon nanocomposite electrocatalytic material comprises the following steps:

[0032] (1) dissolving polyacrylonitrile and methyl methacrylate in N,N'-dimethylformamide to obtain a mixed solution;

[0033] The mass ratio of polyacrylonitrile to N,N'-dimethylformamide is 6:100; the mass ratio of methyl methacrylate to polyacrylonitrile is 30:100;

[0034] (2) adding rhodium trichloride monohydrate to the mixed solution of step (1) and stirring continuously for 8 hours to obtain a spinning solution, and electrospinning the spinning solution to obtain electrospun nanofibers;

[0035] The mass ratio of rhodium trichloride monohydrate to polyacrylonitrile is 0.3:1;

[0036] The electrospinning conditions were as follows: using an electrospinning needle with an inner diameter of 1.2 mm, a voltage of 15 kV, a receiving distance of 14 cm, and an electrospinning propulsion speed of 2 mL / h;

[0037] (3) The electrospun nanofibers prepared in step (2) were heated to 250° C. and kept for 3 h, and then heated to 550° C. and kept for 1.5 h; then, calcined at 800° C. for 4 h under an inert atmosphere, hydrogen was introduced, and the mixture was kept at 800° C. for 2 h to obtain a rhodium@porous carbon fiber composite material;

[0038] (4) weaving the rhodium@porous carbon fiber composite material of step (3) into carbon cloth;

[0039] (5) dispersing nickel nitrate in an aqueous solution of sodium alginate to obtain a dispersion, then arranging carbon in the dispersion, and evaporating the solvent to obtain a carbon cloth gel material;

[0040] The mass ratio of the sodium alginate to the nickel nitrate is 1:0.6;

[0041] (6) The carbon cloth gel material of step (5) was heated at 400°C for 3 hours, then kept at 800°C for 1 hour under an inert atmosphere, and then hydrogen was introduced and kept at 400°C for 3 hours to obtain a bimetallic carbon nanocomposite electrocatalytic material.

[0042] Example 2

[0043] The preparation method of the bimetallic carbon nanocomposite electrocatalytic material comprises the following steps:

[0044] (1) dissolving polyacrylonitrile and methyl methacrylate in N,N'-dimethylformamide to obtain a mixed solution;

[0045] The mass ratio of polyacrylonitrile to N,N'-dimethylformamide is 10:100; the mass ratio of methyl methacrylate to polyacrylonitrile is 50:100;

[0046] (2) adding rhodium trichloride monohydrate to the mixed solution of step (1) and stirring continuously for 10 hours to obtain a spinning solution, and electrospinning the spinning solution to obtain electrospun nanofibers;

[0047] The mass ratio of rhodium trichloride monohydrate to polyacrylonitrile is 0.4:1;

[0048] The electrospinning conditions were as follows: using an electrospinning needle with an inner diameter of 1.0 mm, a voltage of 18 kV, a receiving distance of 15 cm, and an electrospinning propulsion speed of 1 mL / h;

[0049] (3) The electrospun nanofibers prepared in step (2) were heated to 280° C. and kept warm for 2 h, and then heated to 580° C. and kept warm for 2 h; then, calcined at 900° C. for 3 h under an inert atmosphere, hydrogen was introduced, and the mixture was kept warm at 700° C. for 2.5 h to obtain a rhodium@porous carbon fiber composite material;

[0050] (4) weaving the rhodium@porous carbon fiber composite material of step (3) into carbon cloth;

[0051] (5) dispersing nickel nitrate in an aqueous solution of potassium alginate to obtain a dispersion, then arranging carbon in the dispersion, and evaporating the solvent to obtain a carbon cloth gel material;

[0052] Wherein, the mass ratio of the potassium alginate to the nickel nitrate is 1:0.7;

[0053] (6) The carbon cloth gel material of step (5) was heated at 450°C for 2.5 hours, then kept warm at 750°C for 1 hour under an inert atmosphere, and then hydrogen was introduced and kept warm at 380°C for 4 hours to obtain a bimetallic carbon nanocomposite electrocatalytic material.

[0054] The method of catalytic reaction of electrolysis of water is:

[0055] A three-electrode system was formed by using an Ag / AgCl electrode containing saturated potassium chloride as a reference electrode, a platinum wire electrode as a counter electrode, and the bimetallic carbon nanocomposite electrocatalytic material prepared in Example 2 as a working electrode. The system was connected to an electrochemical detection device, and a 0.5 mol sulfuric acid solution was used as the electrolyte. Cyclic voltammetry and linear sweep voltammetry were used to draw working curves.

[0056] Example 3

[0057] The preparation method of the bimetallic carbon nanocomposite electrocatalytic material comprises the following steps:

[0058] (1) dissolving polyacrylonitrile and methyl methacrylate in N,N'-dimethylformamide to obtain a mixed solution;

[0059] The mass ratio of polyacrylonitrile to N,N'-dimethylformamide is 12:100; the mass ratio of methyl methacrylate to polyacrylonitrile is 60:100;

[0060] (2) adding rhodium trichloride monohydrate to the mixed solution of step (1) and stirring continuously for 12 hours to obtain a spinning solution, and electrospinning the spinning solution to obtain electrospun nanofibers;

[0061] The mass ratio of rhodium trichloride monohydrate to polyacrylonitrile is 0.5:1;

[0062] The electrospinning conditions were as follows: using an electrospinning needle with an inner diameter of 0.3 mm, a voltage of 20 kV, a receiving distance of 20 cm, and an electrospinning propulsion speed of 0.5 mL / h;

[0063] (3) The electrospun nanofibers prepared in step (2) were heated to 300°C for 1 hour, and then heated to 600°C for 2 hours; then, the nanofibers were calcined at 1000°C for 1 hour under an inert atmosphere, and then hydrogen was introduced, and the nanofibers were heated at 650°C for 3 hours to obtain a rhodium@porous carbon fiber composite material;

[0064] (4) weaving the rhodium@porous carbon fiber composite material of step (3) into carbon cloth;

[0065] (5) dispersing nickel nitrate in an aqueous solution of sodium alginate to obtain a dispersion, then arranging carbon in the dispersion, and evaporating the solvent to obtain a carbon cloth gel material;

[0066] The mass ratio of the sodium alginate to the nickel nitrate is 1:0.8;

[0067] (6) The carbon cloth gel material of step (5) was heated at 500° C. for 2 h, then kept at 700° C. for 1 h under an inert atmosphere, and then hydrogen was introduced and kept at 350° C. for 5 h to obtain a bimetallic carbon nanocomposite electrocatalytic material.

[0068] Results of electrochemical characterization of the electrode during different modification processes:

[0069] The present invention has carried out XRD test, such as Figure 1 As shown in the figure, XRD results show that rhodium and nickel are successfully compounded in the bimetallic carbon nanocomposite electrocatalyst. At the same time, the peak of the 111 crystal plane of Rh in the electrocatalyst material is significantly broadened compared to Rh, indicating that its crystal structure has been damaged to a certain extent, which is related to its bonding with carbon fiber.

[0070] The obtained bimetallic carbon nanocomposite electrocatalytic material was electrochemically tested;

[0071] The following discusses the performance of bimetallic carbon nanocomposite electrocatalytic materials in the long-term electrocatalytic process, which is also an important indicator for evaluating its performance. Therefore, this application conducted a stability test. Figure 2 As shown, at 10mAcm -2 and 20mAcm -2 The results showed that the bimetallic carbon nanocomposite electrocatalytic material could still maintain its performance for at least 72h.

[0072] Figure 3 It shows that there is still only a slight deviation after 5000 cycles, indicating that the bimetallic carbon nanocomposite electrocatalytic material has good stability.

[0073] Since the material exhibits good HER catalytic performance, in order to further explore its water splitting performance, for the two-electrode water splitting system of bimetallic carbon nanocomposite electrocatalytic material / RuO2, the bimetallic carbon nanocomposite electrocatalytic material is used as the negative electrode, RuO2 is used as the positive electrode, and 0.5molH2SO4 is used as the electrolyte to connect to the electrochemical workstation; the two-electrode water splitting system of Pt / C / / RuO2 is used as the negative electrode, RuO2 is used as the positive electrode, and 0.5molH2SO4 is used as the electrolyte to connect to the electrochemical workstation, and their polarization curves are tested between 1-2V; the two are tested with the same loading of RuO2 as the positive electrode for water splitting, such as Figure 4 As shown, when the potential value reaches 1.72V, it can reach 10mAcm -2 The current density of the present invention will gradually surpass that of the Pt / C / / RuO2 electrode material as the potential value increases.

[0074] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these changes and variations. The above-mentioned embodiments are only preferred embodiments for fully illustrating the present invention, and their scope of protection is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art on the basis of the present invention are all within the scope of protection of the present invention, and the scope of protection of the present invention shall be subject to the claims.

Claims

1. A method for preparing a bimetallic carbon nanocomposite electrocatalytic material, characterized in that: The steps include: (1) Dissolve polyacrylonitrile and methyl methacrylate in N,N ' -dimethylformamide to obtain a mixed solution; (2) adding rhodium trichloride monohydrate to the mixed solution of step (1) and continuously stirring for 8-12 hours to obtain a spinning solution, and electrospinning the spinning solution to obtain electrospun nanofibers; (3) The electrospun nanofibers prepared in step (2) are first heated to 250-300°C and kept warm for 1-3 hours, and then heated to 550-600°C and kept warm for 1.5-2 hours; then, under an inert atmosphere, they are first calcined at 800-1000°C for 1-4 hours, hydrogen is introduced, and then the mixture is kept warm at 650-800°C for 2-3 hours to obtain a rhodium@porous carbon fiber composite material; (4) weaving the rhodium@porous carbon fiber composite material obtained in step (3) into carbon cloth; (5) dispersing nickel nitrate in a carbon source solution to obtain a dispersion, then placing carbon in the dispersion, and evaporating the solvent to obtain a carbon cloth gel material; In step (5), the carbon source is selected from one of sodium alginate, potassium alginate, and lignin, the mass ratio of the carbon source to the nickel nitrate is 1:0.6-0.8, and the mass fraction of the carbon source in the carbon source solution is 1-5%; (6) The carbon cloth gel material of step (5) is heated at 400-500°C for 2-3 hours, then kept at 700-800°C for 1 hour under an inert atmosphere, and then hydrogen is introduced and kept at 350-400°C for 3-5 hours to obtain a bimetallic carbon nanocomposite electrocatalytic material.

2. The method for preparing the bimetallic carbon nanocomposite electrocatalytic material according to claim 1, characterized in that: In the step (1), polyacrylonitrile and N,N ' -The mass ratio of dimethylformamide is 6-12:100; the mass ratio of methyl methacrylate to polyacrylonitrile is 30-60:

100.

3. The method for preparing the bimetallic carbon nanocomposite electrocatalytic material according to claim 1, characterized in that: In the step (2), the mass ratio of rhodium trichloride monohydrate to polyacrylonitrile is 0.3-0.5:

1.

4. The method for preparing the bimetallic carbon nanocomposite electrocatalytic material according to claim 1, characterized in that: The electrospinning conditions in step (2) are as follows: using an electrospinning needle with an inner diameter of 0.3-1.2 mm, advancing at a voltage of 15-20 kV, a receiving distance of 14-20 cm, and an electrospinning propulsion speed of 0.5-2 mL / h.

5. A bimetallic carbon nanocomposite electrocatalytic material prepared by the preparation method according to any one of claims 1 to 4.

6. Use of the bimetallic carbon nanocomposite electrocatalytic material according to claim 5 in the preparation of a water electrolysis catalytic electrode.

7. Use of the bimetallic carbon nanocomposite electrocatalytic material according to claim 6 in preparing a water electrolysis catalytic electrode, characterized in that: The method for the electrolytic water catalytic reaction is: a three-electrode system is composed of an Ag / AgCl electrode containing saturated potassium chloride as a reference electrode, a platinum wire electrode as a counter electrode, and a bimetallic carbon nanocomposite electrocatalytic material as a working electrode, which is connected to an electrochemical detection device, and a sulfuric acid solution with a pH of 0.2-1 is used as an electrolyte to perform water electrolysis operation.

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