A ruthenium-cobalt solid solution oxide nanofiber material, a preparation method thereof, and an application thereof

Abstract

The present invention belongs to the technical field of the preparation of solid solution nanomaterials, and particularly relates to a ruthenium-cobalt solid solution oxide nanofiber material, a preparation method thereof, and an application thereof. The present invention prepares a ruthenium-cobalt solid solution oxide nanofiber material by combining electrospinning technology with calcination in an air atmosphere. The overall performance thereof is a fibrous morphology with a rough and uniform surface, having more exposed active sites and excellent electron transport performance. The preparation method provided by the present invention is simple and easy to implement, has a low cost and a short preparation period, and can realize large-scale industrial production. The ruthenium-cobalt solid solution oxide nanofiber material prepared by the present invention, as a bifunctional electrocatalyst for electrocatalytic water splitting, exhibits excellent hydrogen evolution and oxygen evolution catalytic activities and stability at an industrial current density, realizes efficient, stable, clean and green hydrogen energy production, solves the disadvantages of low activity, poor stability and high price of electrocatalysts in industry, and has high practical application and economic value.

Description

Technical Field

[0001] The present invention belongs to the technical field of the preparation of solid solution nanomaterials, and particularly relates to a ruthenium-cobalt solid solution oxide nanofiber material, a preparation method thereof, and an application in alkaline electrocatalytic hydrogen evolution and oxygen evolution at industrial current density. Background Art

[0002] Nowadays, electrocatalytic water splitting technology is considered as an efficient, feasible and promising green hydrogen production method due to its advantages such as economy, cleanliness and environmental protection. It can be foreseen that this technology can significantly solve problems such as environmental pollution and energy crisis faced by humans. However, low efficiency, high overpotential and excessive use of precious metals result in expensive hydrogen production costs. On the other hand, some currently developed efficient hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) electrocatalysts are mainly applied at low current density (<100 mA / cm 2 ), and cannot be used under the high current density (≥1000 mA / cm 2 ) required for non-industrial hydrogen production. In addition, poor stability at high current density also becomes a key obstacle to its practical application. Therefore, an ideal alkaline water electrolyzer not only requires excellent HER and OER activities, but also requires stability when operating at high current density.

[0003] Generally speaking, to improve the HER and OER performance of electrocatalysts, creating more exposed active sites and improving the electron transfer and mass transfer processes are important conditions. Nanofibers have become ideal candidate materials for HER and OER electrocatalysts due to their advantages in this regard. On the other hand, modulating the electronic structure of electrocatalysts is considered an effective method to improve their electrocatalytic activity. Recently, metal oxide solid solutions have been proven to be efficient OER electrocatalysts. For example, in the rutile-structured ruthenium-manganese oxide solid solution, the strong electron transfer from ruthenium to manganese sites results in a more positive atomic charge at the ruthenium sites, which helps to achieve excellent acidic OER performance (J. Mater. Chem. A, 2023, 11, 25252). However, there is currently no report on the application of solid solution nanofiber-based electrocatalysts in alkaline bifunctional HER and OER at high current density. Therefore, the present invention combines the advantages of nanofibers and solid solution structures to prepare a highly active and stable alkaline HER and OER bifunctional electrocatalyst that can be applied to electrolyze water at industrial current density, laying a foundation for the practical application of electrolyzing water. Summary of the Invention

[0004] To address the above problems, the objective of the present invention is to provide a ruthenium-cobalt solid solution oxide nanofiber material with high efficiency and high stability, its preparation method, and its application in alkaline electrocatalytic HER and OER at industrial-level current densities. The present invention prepares a ruthenium-cobalt solid solution oxide nanofiber material by combining electrospinning technology with calcination in an air atmosphere. Its overall performance shows a fibrous morphology with a rough and uniform surface, having more exposed active sites and excellent electron transport performance.

[0005] The objective of the present invention is achieved through the following technical solutions:

[0006] In the first aspect, the present invention provides a method for preparing a ruthenium-cobalt solid solution oxide nanofiber material, and the steps are as follows:

[0007] A. Preparation of nanofiber membrane by electrospinning method:

[0008] A1. Dissolve 0.2 - 0.4 g of polyvinylpyrrolidone, a certain mass of cobalt salt and ruthenium salt in a mixed solution of 2 - 5 mL of N,N-dimethylformamide and ethanol. The amount of N,N-dimethylformamide or ethanol can be 0. After stirring for 12 hours, a uniform viscous spinning solution precursor is obtained;

[0009] A2. Inject the viscous spinning solution precursor in step A1 into the syringe of the electrospinning device, and perform electrospinning under the conditions of a spinning distance of 15 - 30 cm and a spinning voltage of 12 - 25 kV to obtain a nanofiber membrane on an aluminum foil receiving plate;

[0010] Step B. Calcinate the nanofiber membrane obtained in step A2 in air at 200 - 500 °C for 2 - 4 h to obtain a ruthenium-cobalt solid solution oxide nanofiber material.

[0011] Further, in step A1, the total mass ratio of cobalt salt and ruthenium salt to the mass of polyvinylpyrrolidone is 1:1;

[0012] Further, in step A1, the molar ratio of cobalt salt to ruthenium salt is 1:(1 - 3);

[0013] Further, in step A1, the cobalt salt is one of cobalt acetate, cobalt nitrate or cobalt chloride; the ruthenium salt is one of potassium chlororuthenate, ruthenium chloride or ammonium chlororuthenate;

[0014] Further, in step A1, the molecular weight of polyvinylpyrrolidone is 1000 - 1500 kDa.

[0015] In the second aspect, the present invention provides a ruthenium-cobalt solid solution oxide nanofiber material prepared by any one of the above technical solutions;

[0016] Furthermore, the ruthenium-cobalt solid solution oxide nanofiber is a one-dimensional material with a diameter of 100 to 400 nm and a length greater than 5 μm;

[0017] In a third aspect, the present invention provides an application of a ruthenium-cobalt solid solution oxide nanofiber material in alkaline electrocatalytic hydrogen and oxygen evolution at industrial-grade current density.

[0018] Beneficial effects of the present invention:

[0019] 1. The ruthenium-cobalt solid solution oxide nanomaterial provided by the present invention has a rough and uniform fiber morphology as a whole, has a large number of exposed active sites and excellent electron transport performance.

[0020] 2. The preparation method of the ruthenium-cobalt solid solution oxide provided by the present invention is simple, easy, low-cost and has a short preparation cycle, and is expected to achieve industrial large-scale production.

[0021] 3. The ruthenium-cobalt solid solution oxide nanofiber material provided by the present invention can be used as a bifunctional catalyst for water electrolysis at industrial-grade current density. By adjusting the ratio of ruthenium and cobalt elements, it exhibits excellent catalytic activity, effectively improving the stability of the reaction and reducing the overpotential required for the reaction. Its electrocatalytic HER and OER current density reaches 1A / cm 2 When , the required overpotential is only 149mV and 362mV respectively, and the catalytic stability reaches 120h, which meets the needs of practical industrial applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art; obviously, the drawings described below are some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0023] Figure 1 This is a scanning electron microscope image of the ruthenium-cobalt solid solution oxide nanofibers prepared in Example 1;

[0024] Figure 2 This is the X-ray diffraction pattern of the ruthenium-cobalt solid solution oxide nanofibers prepared in Example 1;

[0025] Figure 3 A comparison of polarization curves of the OER process of the ruthenium-cobalt solid solution oxide nanofiber material prepared in Example 1, the ruthenium dioxide nanofiber material prepared in Comparative Example 1, and the cobalt oxide nanomaterial prepared in Comparative Example 2;

[0026] Figure 4Polarization curve comparison diagram of the HER process of the ruthenium-cobalt solid solution oxide nanofiber material prepared in Example 2, the ruthenium dioxide nanofiber material prepared in Comparative Example 1, and the cobalt tetroxide nanomaterial prepared in Comparative Example 2;

[0027] Figure 5 Time-current curve diagram of the OER process of the ruthenium-cobalt solid solution oxide nanofibers prepared in Example 1;

[0028] Figure 6 Time-current curve diagram of the HER process of the ruthenium-cobalt solid solution oxide nanofibers prepared in Example 2; Detailed implementation manners

[0029] For ease of understanding of the present invention, the present invention will be described more comprehensively below. Preferred embodiments of the present invention are given in specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. It should be understood that the appended claims define the scope of the present invention, and those skilled in the art should be aware that certain changes made to the embodiments of the present invention will be covered by the spirit and scope of the claims of the present invention.

[0030] Example 1

[0031] Dissolve 0.3 g of polyvinylpyrrolidone (molecular weight 1300 kDa), 0.1125 g of cobalt acetate and 0.1875 g of ruthenium chloride (molar ratio 1:2) in a mixed solution of 1.8 mL of N,N-dimethylformamide and 1.8 mL of ethanol, and then stir for 12 hours to obtain a uniform viscous spinning solution precursor; inject the spinning solution precursor into the syringe of the electrospinning device, and perform electrospinning under the conditions of a spinning distance of 20 cm and a spinning voltage of 18 kV, so as to obtain a nanofiber membrane on an aluminum foil receiving plate; calcine the obtained nanofiber membrane in air at 300 °C for 2 hours to obtain a ruthenium-cobalt solid solution oxide nanofiber material catalyst, and the product presents a black film shape.

[0032] Example 2

[0033] Dissolve 0.3 g of polyvinylpyrrolidone (molecular weight 1300 kDa), 0.1636 g of cobalt acetate and 0.1364 g of ruthenium chloride (molar ratio 1:1) in a mixed solution of 1.8 mL of N,N-dimethylformamide and 1.8 mL of ethanol, and then stir for 12 hours to obtain a uniform viscous spinning solution precursor; Inject the spinning solution precursor into the syringe of the electrospinning device, and perform electrospinning under the conditions of a spinning distance of 20 cm and a spinning voltage of 18 kV to obtain a nanofiber membrane on an aluminum foil receiving plate; Calcinate the obtained nanofiber membrane in air at 300 °C for 2 hours to obtain a ruthenium cobalt solid solution oxide nanofiber material catalyst, and the product presents a black film shape.

[0034] Example 3

[0035] Dissolve 0.3 g of polyvinylpyrrolidone (molecular weight 1000 kDa), 0.086 g of cobalt acetate and 0.214 g of ruthenium chloride (molar ratio 1:3) in a mixed solution of 1.8 mL of N,N-dimethylformamide and 1.8 mL of ethanol, and then stir for 12 hours to obtain a uniform viscous spinning solution precursor; Inject the spinning solution precursor into the syringe of the electrospinning device, and perform electrospinning under the conditions of a spinning distance of 20 cm and a spinning voltage of 18 kV to obtain a nanofiber membrane on an aluminum foil receiving plate; Calcinate the obtained nanofiber membrane in air at 300 °C for 2 hours to obtain a ruthenium cobalt solid solution oxide nanofiber material catalyst, and the product presents a black film shape.

[0036] Example 4

[0037] Dissolve 0.3 g of polyvinylpyrrolidone (molecular weight 1300 kDa), 0.175 g of cobalt nitrate and 0.125 g of ruthenium chloride (molar ratio 1:1) in a mixed solution of 1.8 mL of N,N-dimethylformamide and 1.8 mL of ethanol, and then stir for 12 hours to obtain a uniform viscous spinning solution precursor; Inject the spinning solution precursor into the syringe of the electrospinning device, and perform electrospinning under the conditions of a spinning distance of 20 cm and a spinning voltage of 18 kV to obtain a nanofiber membrane on an aluminum foil receiving plate; Calcinate the obtained nanofiber membrane in air at 300 °C for 2 hours to obtain a ruthenium cobalt solid solution oxide nanofiber material catalyst.

[0038] Example 5

[0039] Dissolve 0.3 g of polyvinylpyrrolidone (molecular weight 1300 kDa), 0.125 g of cobalt acetate and 0.175 g of ammonium chlororuthenate (molar ratio 1:1) in a mixed solution of 1.8 mL of N,N-dimethylformamide and 1.8 mL of ethanol, and then stir for 12 hours to obtain a homogeneous viscous spinning solution precursor; Inject the spinning solution precursor into the syringe of the electrospinning device, and perform electrospinning under the conditions of a spinning distance of 20 cm and a spinning voltage of 18 kV to obtain a nanofiber membrane on an aluminum foil receiving plate; Calcinate the obtained nanofiber membrane in air at 300 °C for 2 hours to obtain a ruthenium-cobalt solid solution oxide nanofiber material catalyst.

[0040] Example 6

[0041] Dissolve 0.3 g of polyvinylpyrrolidone (molecular weight 1300 kDa), 0.1125 g of cobalt acetate and 0.1875 g of ruthenium chloride (molar ratio 1:2) in a mixed solution of 1.8 mL of N,N-dimethylformamide and 1.8 mL of ethanol, and then stir for 12 hours to obtain a homogeneous viscous spinning solution precursor; Inject the spinning solution precursor into the syringe of the electrospinning device, and perform electrospinning under the conditions of a spinning distance of 20 cm and a spinning voltage of 18 kV to obtain a nanofiber membrane on an aluminum foil receiving plate; Calcinate the obtained nanofiber membrane in air at 400 °C for 2 hours to obtain a ruthenium-cobalt solid solution oxide nanofiber material catalyst.

[0042] Example 7

[0043] Dissolve 0.3 g of polyvinylpyrrolidone (molecular weight 1300 kDa), 0.1125 g of cobalt acetate and 0.1875 g of ruthenium chloride (molar ratio 1:2) in a mixed solution of 1.8 mL of N,N-dimethylformamide and 1.8 mL of ethanol, and then stir for 12 hours to obtain a homogeneous viscous spinning solution precursor; Inject the spinning solution precursor into the syringe of the electrospinning device, and perform electrospinning under the conditions of a spinning distance of 20 cm and a spinning voltage of 18 kV to obtain a nanofiber membrane on an aluminum foil receiving plate; Calcinate the obtained nanofiber membrane in air at 200 °C for 2 hours to obtain a ruthenium-cobalt solid solution oxide nanofiber material catalyst.

[0044] Example 8

[0045] Dissolve 0.3 g of polyvinylpyrrolidone (molecular weight 1300 kDa), 0.1125 g of cobalt acetate and 0.1875 g of ruthenium chloride (molar ratio 1:2) in a mixed solution of 1.8 mL of N,N-dimethylformamide and 1.8 mL of ethanol, and then stir for 12 hours to obtain a homogeneous viscous spinning solution precursor; Inject the spinning solution precursor into the syringe of the electrospinning device, and perform electrospinning under the conditions of a spinning distance of 20 cm and a spinning voltage of 20 kV to obtain a nanofiber membrane on an aluminum foil receiving plate; Calcinate the obtained nanofiber membrane in air at 300 °C for 2 hours to obtain a ruthenium-cobalt solid solution oxide nanofiber material catalyst.

[0046] Example 9

[0047] Dissolve 0.3 g of polyvinylpyrrolidone (molecular weight 1300 kDa), 0.1125 g of cobalt acetate and 0.1875 g of ruthenium chloride (molar ratio 1:2) in 3.6 mL of N,N-dimethylformamide, and then stir for 12 hours to obtain a homogeneous viscous spinning solution precursor; Inject the spinning solution precursor into the syringe of the electrospinning device, and perform electrospinning under the conditions of a spinning distance of 20 cm and a spinning voltage of 18 kV to obtain a nanofiber membrane on an aluminum foil receiving plate; Calcinate the obtained nanofiber membrane in air at 300 °C for 2 hours to obtain a ruthenium-cobalt solid solution oxide nanofiber material catalyst.

[0048] Example 10

[0049] Dissolve 0.3 g of polyvinylpyrrolidone (molecular weight 1300 kDa), 0.1125 g of cobalt acetate and 0.1875 g of ruthenium chloride (molar ratio 1:2) in 3.6 mL of ethanol, and then stir for 12 hours to obtain a homogeneous viscous spinning solution precursor; Inject the spinning solution precursor into the syringe of the electrospinning device, and perform electrospinning under the conditions of a spinning distance of 20 cm and a spinning voltage of 18 kV to obtain a nanofiber membrane on an aluminum foil receiving plate; Calcinate the obtained nanofiber membrane in air at 300 °C for 2 hours to obtain a ruthenium-cobalt solid solution oxide nanofiber material catalyst.

[0050] Example 11

[0051] Dissolve 0.3 g of polyvinylpyrrolidone (molecular weight 1300 kDa), 0.1125 g of cobalt acetate and 0.1875 g of ruthenium chloride (molar ratio 1:2) in a mixed solution of 1.5 mL of N,N-dimethylformamide and 1.5 mL of ethanol, and then stir for 12 hours to obtain a uniform viscous spinning solution precursor; Inject the spinning solution precursor into the syringe of the electrospinning device, and perform electrospinning under the conditions of a spinning distance of 20 cm and a spinning voltage of 18 kV to obtain a nanofiber membrane on an aluminum foil receiving plate; Calcinate the obtained nanofiber membrane in air at 300 °C for 2 hours to obtain a ruthenium cobalt solid solution oxide nanofiber material catalyst.

[0052] Example 12

[0053] Dissolve 0.3 g of polyvinylpyrrolidone (molecular weight 1500 kDa), 0.1125 g of cobalt acetate and 0.1875 g of ruthenium chloride (molar ratio 1:2) in a mixed solution of 1.8 mL of N,N-dimethylformamide and 1.8 mL of ethanol, and then stir for 12 hours to obtain a uniform viscous spinning solution precursor; Inject the spinning solution precursor into the syringe of the electrospinning device, and perform electrospinning under the conditions of a spinning distance of 20 cm and a spinning voltage of 18 kV to obtain a nanofiber membrane on an aluminum foil receiving plate; Calcinate the obtained nanofiber membrane in air at 300 °C for 2 hours to obtain a ruthenium cobalt solid solution oxide nanofiber material catalyst.

[0054] Example 13

[0055] Disperse the ruthenium cobalt solid solution oxide nanofiber catalysts prepared in Examples 1 and 2 into a mixed solution of water, ethanol and Nafion (the mass ratio of water, ethanol and Nafion is 490:490:20) to prepare a dispersion with a concentration of 4 mg / mL; Then drop 22.5 μL of the dispersion on a carbon paper with an area of 9 mm2 and dry it naturally in air to obtain a carbon paper loaded with the catalyst; Test the prepared carbon paper in an electrolytic cell. The test system is a three-electrode system (the carbon paper loaded with the catalyst is the working electrode, a carbon rod (for HER test) or a platinum wire (for OER test) is the counter electrode, and a mercury oxide electrode (Hg / HgO) is the reference electrode), and the electrolyte is 1 mol / L KOH solution. Before the test, pass Ar into the electrolytic cell until saturation, and always maintain an Ar atmosphere during the test. Evaluate the OER and HER activities respectively, and perform a polarization curve test (LSV) with a scanning speed of 2 mV / s. At the same current density, the greater the overpotential, the lower the ability to produce oxygen and hydrogen. It should be noted that all the potentials obtained with a mercury oxide reference electrode in the electrocatalytic test are converted to reversible hydrogen electrode potentials in the property diagram, and the external power supply is the main battery of the electrochemical workstation.

[0056] Example 14

[0057] The ruthenium-cobalt solid solution oxide nanofiber catalyst prepared in Example 3 was dispersed in a mixed solution of water, ethanol and Nafion (the mass ratio of water, ethanol and Nafion was 490:490:20) to prepare a dispersion with a concentration of 4 mg / mL; then 22.5 μL of the dispersion was dropped on a carbon paper with an area of 9 mm 2 and air-dried naturally to obtain carbon paper loaded with the catalyst; the prepared carbon paper was tested in an electrolytic cell, and the test system was a three-electrode system (the carbon paper loaded with the catalyst was the working electrode, a carbon rod (for HER test) or a platinum wire (for OER test) was the counter electrode, and a mercury oxide electrode (Hg / HgO) was the reference electrode), and the electrolyte was 1 mol / L KOH solution. Before the test, Ar was introduced into the electrolytic cell until saturation, and the Ar atmosphere was maintained throughout the test. The OER and HER activities were evaluated separately, and a polarization curve test (LSV) was performed at a scanning rate of 2 mV / s.

[0058] Comparative Example 1

[0059] First, 0.3 g of polyvinylpyrrolidone (molecular weight 1300 kDa) and 0.3 g of ruthenium chloride were dissolved in a mixed solution of 1.8 mL of N,N-dimethylformamide and 1.8 mL of ethanol, and then stirred for 12 hours to obtain a uniform viscous spinning solution precursor; the spinning solution precursor was injected into the syringe of an electrospinning device, and electrospinning was carried out under the conditions of a spinning distance of 20 cm and a spinning voltage of 18 kV to obtain a nanofiber membrane on an aluminum foil receiving plate; the obtained nanofiber membrane was calcined in air at 300 °C for 2 hours to obtain a ruthenium dioxide nanofiber material catalyst as a product, and the product was nanofibers with the same morphology as in Example 1.

[0060] Comparative Example 2

[0061] First, 0.3 g of polyvinylpyrrolidone (molecular weight 1300 kDa) and 0.3 g of cobalt acetate were dissolved in a mixed solution of 1.8 mL of N,N-dimethylformamide and 1.8 mL of ethanol, and then stirred for 12 hours to obtain a uniform viscous spinning solution precursor; the spinning solution precursor was injected into the syringe of an electrospinning device, and electrospinning was carried out under the conditions of a spinning distance of 20 cm and a spinning voltage of 18 kV to obtain a nanofiber membrane on an aluminum foil receiving plate; the obtained nanofiber membrane was calcined in air at 300 °C for 2 hours to obtain a cobalt tetroxide nanomaterial as a product. The product showed a morphology with coexisting nanofibers / nanoparticles.

[0062] Comparative Example 3

[0063] The ruthenium dioxide nanofiber material catalyst prepared in Comparative Example 1 was dispersed in a mixed solution of water, ethanol, and Nafion (the mass ratio of water, ethanol, and Nafion was 490:490:20) to prepare a dispersion with a concentration of 4 mg / mL; then 22.5 μL of the dispersion was dropped on carbon paper with an area of 9 mm 2 . It was naturally dried in air to obtain carbon paper loaded with the catalyst; the prepared carbon paper was tested in an electrolytic cell. The test system was a three-electrode system (the carbon paper loaded with the catalyst was the working electrode, a carbon rod (for HER test) or a platinum wire (for OER test) was the counter electrode, and a mercury oxide electrode (Hg / HgO) was the reference electrode), and the electrolyte was 1 mol / L KOH solution. Before the test, Ar was introduced into the electrolytic cell until saturation, and the Ar atmosphere was maintained throughout the test. The OER and HER activities were evaluated separately, and a polarization curve test (LSV) was performed at a scanning rate of 2 mV / s.

[0064] Comparative Example 4

[0065] The cobalt cobalt oxide nanofiber material catalyst prepared in Comparative Example 2 was dispersed in a mixed solution of water, ethanol, and Nafion (the mass ratio of water, ethanol, and Nafion was 490:490:20) to prepare a dispersion with a concentration of 4 mg / mL; then 22.5 μL of the dispersion was dropped on carbon paper with an area of 9 mm 2 . It was naturally dried in air to obtain carbon paper loaded with the catalyst; the prepared carbon paper was tested in an electrolytic cell. The test system was a three-electrode system (the carbon paper loaded with the catalyst was the working electrode, a carbon rod (for HER test) or a platinum wire (for OER test) was the counter electrode, and a mercury oxide electrode (Hg / HgO) was the reference electrode), and the electrolyte was 1 mol / L KOH solution. Before the test, Ar was introduced into the electrolytic cell until saturation, and the Ar atmosphere was maintained throughout the test. The OER and HER activities were evaluated separately, and a polarization curve test (LSV) was performed at a scanning rate of 2 mV / s.

[0066] Figure 1 is the scanning electron microscope (SEM) image of the ruthenium cobalt solid solution oxide nanofibers prepared in Example 1. It can be seen that the material is one-dimensional nanofibers with a rough surface and uniform diameter, with a diameter of 150 - 300 nm and a length greater than 5 μm.

[0067] Figure 2 is the X-ray diffraction (XRD) pattern of the ruthenium cobalt solid solution oxide nanofibers prepared in Example 1. It can be seen that the main body of the obtained product is a solid solution phase of ruthenium cobalt oxide.

[0068] Figure 3Comparison of linear sweep voltammetry polarization curves of ruthenium-cobalt solid solution oxide nanofiber material catalysts prepared in Example 1, ruthenium dioxide nanofiber material catalysts prepared in Comparative Example 1, and cobalt tetroxide nanomaterial catalysts prepared in Comparative Example 2 for OER in potassium hydroxide (1 M KOH) solution. The overpotentials of the ruthenium-cobalt solid solution oxide nanofiber material catalysts at current densities of 100 mA / cm 2 and 1 A / cm 2 are 260 mV and 362 mV, which are much better than those of the ruthenium dioxide nanofiber material catalysts (the overpotentials at current densities of 100 mA / cm 2 and 1 A / cm 2 are 327 mV and 734 mV) and the cobalt tetroxide nanomaterial catalysts (the overpotentials at current densities of 100 mA / cm 2 and 1 A / cm 2 are 480 mV and 782 mV), indicating that the materials of the present invention have excellent OER catalytic activity.

[0069] Figure 4 Linear sweep voltammetry polarization curves of ruthenium-cobalt solid solution oxide nanofiber material catalysts prepared in Example 2, ruthenium dioxide nanofiber material catalysts prepared in Comparative Example 1, and cobalt tetroxide nanomaterial catalysts prepared in Comparative Example 2 for HER in potassium hydroxide (1 M KOH) solution. The overpotentials of the ruthenium-cobalt solid solution oxide nanofiber material at current densities of 100 mA / cm 2 and 1 A / cm 2 are 56 mV and 149 mV, which are much better than those of the ruthenium dioxide nanofiber material catalysts (the overpotentials at current densities of 100 mA / cm 2 and 1 A / cm 2 are 94 mV and 335 mV) and the cobalt tetroxide nanomaterial catalysts prepared in Comparative Example 2 (the overpotential at current density of 100 mA / cm 2 is 574 mV); and the electrocatalytic hydrogen evolution performance of the cobalt tetroxide nanomaterial catalysts is significantly reduced and it is difficult to reach a high current density; indicating that the materials of the present invention have excellent HER catalytic activity.

[0070] Figure 5 Time-current curve of the ruthenium-cobalt solid solution oxide nanofiber material catalyst prepared in Example 1 for OER in potassium hydroxide (1 M KOH) solution. At a current density of 1 A / cm 2 , the catalyst can be stable for 120 h with almost no obvious attenuation of the current density. It shows that the materials of the present invention have excellent stability for the OER process at industrial-level high current densities.

[0071] Figure 6Time-current curve of the ruthenium-cobalt solid solution oxide nanofiber material catalyst prepared in Example 2 for HER in a potassium hydroxide (1 M KOH) solution. At a current density of 1 A / cm 2 , the catalyst can be stable for 120 h with almost no obvious attenuation of the current density. This indicates that the material of the present invention has excellent stability for the HER process at an industrial-level high current density.

[0072] The above-described embodiments merely represent several implementation manners of the present invention. The description thereof is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the invention patent shall be subject to the appended claims.

Claims

1. A method for preparing a ruthenium-cobalt solid solution oxide nanofiber material, the steps are as follows: A. Preparation of nanofiber membrane by electrospinning method: A1. Dissolve 0.2 - 0.4 g of polyvinylpyrrolidone, a certain mass of cobalt salt and ruthenium salt in 2 - 5 mL of a mixed solution of N,N-dimethylformamide and ethanol. The amount of N,N-dimethylformamide or ethanol can be 0. After stirring for 12 hours, a uniform viscous spinning solution precursor is obtained; The mass ratio of the total mass of the cobalt salt and ruthenium salt to the mass of polyvinylpyrrolidone is 1:1; The molar ratio of the cobalt salt to the ruthenium salt is 1:(1 - 3); A2. Inject the viscous spinning solution precursor in step A1 into the syringe of the electrospinning device, and perform electrospinning under the conditions of a spinning distance of 15 - 30 cm and a spinning voltage of 12 - 25 kV to obtain a nanofiber membrane on an aluminum foil receiving plate; B. Calcinate the nanofiber membrane obtained in step A2 in air at 200 - 500 °C for 2 - 4 h to obtain a ruthenium-cobalt solid solution oxide nanofiber material.

2. The preparation method of a ruthenium-cobalt solid solution oxide nanofiber material according to claim 1, characterized in that, In step A1, the cobalt salt is one of cobalt acetate, cobalt nitrate or cobalt chloride; the ruthenium salt is one of potassium chlororuthenate, ruthenium chloride or ammonium chlororuthenate.

3. The preparation method of a ruthenium-cobalt solid solution oxide nanofiber material according to claim 1, wherein, In step A1, the molecular weight of polyvinylpyrrolidone is 1000 - 1500 kDa.

4. A ruthenium-cobalt solid solution oxide nanofiber material, characterized in that, It is prepared by the method described in any one of claims 1 - 3.

5. A ruthenium-cobalt solid solution oxide nanofiber material according to claim 4, characterized in that, The ruthenium-cobalt solid solution oxide nanofiber is a one-dimensional material with a diameter of 100 - 400 nm and a length greater than 5 μm.

6. An application of a ruthenium-cobalt solid solution oxide nanofiber material according to claim 4 in alkaline electrocatalytic hydrogen evolution and oxygen evolution at industrial current density.

Images