Cobaltosic oxide loaded ruthenium dioxide fiber as well as preparation method and application thereof

Abstract

The invention discloses cobaltosic oxide loaded ruthenium dioxide fibers as well as a preparation method and application thereof, and relates to the technical field of electrolyzed water. The preparation method comprises the following steps: carrying out wet spinning on sodium alginate and calcium chloride to prepare calcium alginate fibers, then sequentially reacting the calcium alginate fibers with hydrochloric acid and cobalt chloride, calcining to obtain cobaltosic oxide fibers, reacting the cobaltosic oxide fibers with ruthenium trichloride, and carbonizing to obtain the cobaltosic oxide loaded ruthenium dioxide fibers. According to the invention, Co3O4 is utilized to transfer electrons to RuO2, so that the valence state of ruthenium is reduced, and dissolution of high-valence ruthenium in an acidic OER process can be inhibited, so that the OER activity under an acidic medium is improved, and the stability can be improved. Specifically, in a 0.1 M HClO4 electrolyte, under the current density of 10 mA / cm < 2 >, the overpotential is 220 mV, and the voltage is basically unchanged after continuous testing for 100 h.

Description

Technical Field

[0001] The present invention relates to the technical field of electrolyzed water, and particularly to a ruthenium dioxide-loaded cobalt tetroxide fiber and a preparation method and application thereof. Background Art

[0002] Hydrogen is regarded as an ideal energy carrier due to its advantages of being clean, pollution-free, efficient, and storable. Hydrogen production by electrolyzing water is currently the most efficient and convenient method for producing hydrogen. According to the types of electrolytes and transfer ions, electrolyzed water is divided into alkaline electrolyzed water, proton exchange membrane electrolyzed water, and solid oxide electrolyzed water. Among them, although the alkaline electrolyzed water technology is mature, the use of alkaline electrolytes will cause corrosion, and the generated gas contains alkali mist that needs to be purified. In addition, the use of porous diaphragms also limits the working current density and electrolysis efficiency. Although solid oxide electrolyzed water can avoid the use of precious metals, the durability problems of ceramic materials at high temperatures and during long-term operation limit its application. Proton exchange membrane electrolyzed water has the advantages of low ohmic resistance, high current density, and good compatibility with sustainable energy, and is considered to be the most promising method for electrolyzing water at present.

[0003] Currently, due to the lack of effective and stable electrocatalysts, the development of proton exchange membrane electrolyzed water is restricted by the anodic oxygen evolution reaction (OER). For example, noble metal ruthenium-based materials, as commonly used electrocatalysts, due to their unsatisfactory stability, will form soluble substances such as RuO 4 during the acidic OER process, resulting in performance degradation. At the same time, the content of Ru noble metal in noble metal ruthenium-based materials usually exceeds 80 wt%, and Ru is costly and scarce in resources. Therefore, the development of high-performance and high-stability catalysts for proton exchange membrane electrolyzed water is currently a research hotspot.

[0004] In the prior art, "Preparation of RuO 2 / Co 3 O 4 @NC Composite Materials and Their Electrocatalytic Overall Water Splitting Performance" (Li Xiao et al., Acta Compositae Sinica, December 2024) discloses that ZIF-L-Co is first calcined in an inert gas to obtain Co 3 O 4 coated with a graphite carbon layer, that is, Co@CN. Then, an RuCl 3 solution is dropped onto the surface of Co@CN and calcined in air, so that RuO 2 is loaded on the surface of Co 3 O 4 @NC nanoparticles to obtain RuO 2 / Co 3 O 4@NC composite materials. Although the prepared composite materials have good OER and HER catalytic activities under alkaline medium conditions, the Co in its core 3 O 4 will regulate the electronic structure of the surface RuO 2 to make it in a high valence state, and the increase of Ru valence state will bring the problem of poor stability. In addition, when it is used for the OER process in a strong acidic medium, the high valence Ru is very easy to react with H + to generate soluble Ru ions, resulting in the loss of active components, and then leading to an irreversible decay of OER activity.

[0005] Therefore, it is particularly necessary to develop high-performance and high-stability electrocatalysts to improve their OER activity and stability when used in proton exchange membrane water electrolysis. Summary of the Invention

[0006] In view of the above-mentioned prior art, the object of the present invention is to provide a ruthenium dioxide fiber supported on cobalt tetroxide, its preparation method and application. The present invention uses sodium alginate and calcium chloride to prepare calcium alginate fibers by wet spinning, and then reacts the calcium alginate fibers with hydrochloric acid and cobalt chloride in sequence and then calcines them to obtain cobalt tetroxide fibers, and then reacts them with ruthenium trichloride and then carbonizes them to obtain ruthenium dioxide fibers supported on cobalt tetroxide. The present invention utilizes Co 3 O 4 to transfer electrons to RuO 2 , resulting in a decrease in the valence state of ruthenium, which can not only inhibit the dissolution of high-valence ruthenium during the acidic OER process, thereby improving the OER activity in acidic media, but also improve the stability. Specifically, in a 0.1 M HClO 4 electrolyte and a current density of 10 mA / cm 2 , the overpotential is 220 mV, and the voltage remains basically unchanged after continuous testing for 100 h.

[0007] To achieve the above object, the present invention adopts the following technical solutions: In the first aspect of the present invention, a preparation method of ruthenium dioxide fiber supported on cobalt tetroxide is provided, including the following steps: (1) Using sodium alginate and calcium chloride solution as raw materials, through wet spinning, calcium alginate fibers are obtained; mixing the calcium alginate fibers with hydrochloric acid and reacting to obtain hydrogen alginate fibers; mixing the hydrogen alginate fibers with cobalt chloride solution and reacting to obtain cobalt alginate fibers; calcining the cobalt alginate fibers to obtain cobalt tetroxide fibers; (2) Mixing the cobalt tetroxide fibers and ruthenium trichloride solution for hydrothermal reaction to obtain cobalt tetroxide fibers loaded with ruthenium precursors; carbonizing the cobalt tetroxide fibers loaded with ruthenium precursors to obtain ruthenium dioxide fibers supported on cobalt tetroxide.

[0008] Preferably, in step (1), the mass fraction of the sodium alginate solution is 0.8% - 1.2%; the mass fraction of the calcium chloride solution is 3.5% - 4.5%.

[0009] Preferably, in step (1), the specific steps of wet spinning are as follows: extrude the sodium alginate solution through a spinneret and then enter a coagulation bath containing calcium chloride solution for solidification and forming to obtain nascent fibers; wash the nascent fibers with water, stretch and dry them to obtain calcium alginate fibers.

[0010] Further, the residence time of the sodium alginate solution in the coagulation bath after extrusion through the spinneret is 15 - 25 s, and the temperature of the coagulation bath is 25 - 35 °C; the linear velocity of the sodium alginate solution after extrusion through the spinneret is 10 - 15 m / min; the draw ratio is 0.90 - 0.92%.

[0011] Preferably, in step (1), the concentration of hydrochloric acid is 0.8 - 1.2 mol / L.

[0012] Preferably, in step (1), the addition ratio of cobalt chloride in calcium alginate fibers, hydrochloric acid, and cobalt chloride solution is (0.8 - 1.2) g : 100 mL : 500 mg.

[0013] Preferably, in step (1), the cobalt chloride solution is prepared by mixing cobalt chloride, water, and ethanol according to the material ratio of (450 - 550) mg : 50 mL : 50 mL.

[0014] Preferably, in step (1), the reaction time of calcium alginate fibers and hydrochloric acid is 150 - 200 min; the reaction time of calcium hydrogen alginate fibers and cobalt chloride solution is 250 - 350 min.

[0015] Preferably, in step (1), the specific operation of calcination is as follows: place the cobalt alginate fibers in an air atmosphere, heat them to 450 - 550 °C at a heating rate of 1 - 3 °C / min, and then keep them calcined for 1.5 - 2.5 h.

[0016] Preferably, in step (2), the mass fraction of the ruthenium trichloride solution is 0.08% - 0.10%.

[0017] Preferably, in step (2), the addition amount of cobalt tetroxide fibers and ruthenium trichloride solution is (0.08 - 0.12) g : 50 mL.

[0018] Preferably, in step (2), the hydrothermal reaction temperature is 110 - 130 °C, and the hydrothermal reaction time is 2.5 - 3.5 h.

[0019] Preferably, in step (2), the carbonization operation is as follows: placing the cobalt tetroxide fiber loaded with ruthenium precursor in an air atmosphere, heating it to 250-350 °C at a heating rate of 3-6 °C / min, and performing heat preservation treatment for 2.5-3.5 h to obtain cobalt tetroxide supported ruthenium dioxide fiber.

[0020] In the second aspect of the present invention, there is provided cobalt tetroxide supported ruthenium dioxide fiber prepared by the above preparation method.

[0021] In the third aspect of the present invention, there is provided the application of the above cobalt tetroxide supported ruthenium dioxide fiber in electrolyzing water or seawater in an acidic medium.

[0022] Preferably, the acidic medium is HClO solution with a concentration of 0.05-0.15 M. 4 Solution.

[0023] Advantages of the present invention: 1. In the present invention, sodium alginate solution and calcium chloride solution are subjected to wet spinning to obtain calcium alginate fiber, then the calcium alginate fiber is reacted with hydrochloric acid and cobalt chloride solution in sequence to obtain cobalt alginate fiber, and the cobalt alginate fiber is calcined to obtain cobalt tetroxide fiber; the cobalt tetroxide fiber and ruthenium trichloride solution are subjected to hydrothermal reaction and then carbonized to obtain cobalt tetroxide supported ruthenium dioxide fiber. The cobalt tetroxide supported ruthenium dioxide fiber prepared by the present invention has high catalytic activity and good stability as an electrocatalyst. Specifically, its overpotential at a current density of 10 mA / cm² in 0.1 M HClO electrolyte is 220 mV, and after testing in 0.1 M HClO electrolyte for 100 h, its voltage remains basically unchanged, having excellent catalytic stability. 4 In the electrolyte at a current density of 2 10 mA / cm², the overpotential is 220 mV, and after testing in 0.1 M HClO 4 electrolyte for 100 h, its voltage remains basically unchanged, having excellent catalytic stability.

[0024] 2. For the cobalt tetroxide supported ruthenium dioxide fiber prepared by the present invention, cobalt tetroxide serves as an electron donor, and electrons are transferred from Co to Ru, reducing the oxidation state of Ru. This electron transfer changes the local electronic structure of Ru, thereby reducing the valence state of Ru and enabling it to exist in a stable medium or low valence state. At the same time, by reducing the valence state of Ru, the dissolution of high-valent ruthenium during the acidic OER process is inhibited.

[0025] Therefore, in the present invention, the valence state of Ru is reduced through the electron donor effect of Co 3 O 4 , effectively inhibiting the generation and dissolution of high-valent Ru during the acidic OER process. This mechanism not only improves the stability of the catalyst but also enhances its intrinsic catalytic activity by optimizing the electronic state of Ru, thereby achieving efficient and durable OER performance in an acidic medium.

[0026] 3. The ruthenium dioxide - supported cobalt tetroxide fibers prepared by the present invention have an obvious one - dimensional structure and abundant pores. This structure increases the contact area between the ruthenium dioxide - supported cobalt tetroxide fiber catalyst and the electrolyte, promoting the transport of the electrolyte and the release of O 2 .

[0027] 4. Using sodium alginate as the raw material, which has a wide source, is environmentally friendly, green, and highly safe. It is a huge renewable resource and an ideal raw material for preparing hollow fiber materials. The method of the present invention can be used to prepare a large amount of ruthenium dioxide - supported cobalt tetroxide fibers without expensive equipment and can be widely used in the electrolysis of seawater. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 : SEM images of the ruthenium dioxide - supported cobalt tetroxide fibers prepared in Example 1; among them, (a) is the SEM image at a scale of 4 μm, and (b) is the SEM image at a scale of 10 μm; Figure 2 : XRD pattern of the ruthenium dioxide - supported cobalt tetroxide fibers prepared in Example 1; Figure 3 : Transmission electron microscope image of the ruthenium dioxide - supported cobalt tetroxide fibers prepared in Example 1; Figure 4 : Energy spectrum diagram of the ruthenium dioxide - supported cobalt tetroxide fibers prepared in Example 1; Figure 5 : OER performance diagrams of different electrocatalysts in acidic electrolyte in Test Example 1; Figure 6 : OER stability diagrams of different electrocatalysts in acidic electrolyte in Test Example 1; Figure 7 : Performance diagrams of ruthenium dioxide - supported cobalt tetroxide fibers in acidic electrolytic simulated seawater in Test Example 2; Figure 8 : Performance diagrams of ruthenium dioxide - supported cobalt tetroxide fibers in acidic electrolytic seawater in Test Example 2. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present application belongs.

[0030] At present, proton exchange membrane electrolysis of water is considered to be the most promising method for water electrolysis due to its low ohmic resistance, high current density, good compatibility with sustainable energy, etc. However, since a strongly acidic medium is required for proton exchange membrane electrolysis of water, developing an electrocatalyst with high OER activity and high stability for proton exchange membrane electrolysis of water is a current research and development hotspot.

[0031] Although RuO 2 / Co 3 O 4 @NC composite materials can be used as electrocatalysts for water electrolysis, but in the above electrocatalysts, the inner core Co 3 O 4 will adjust the electronic structure of the surface RuO 2 to make it in a high valence state. The increase in the Ru valence state will bring the problem of poor stability. In addition, when it is used in a strongly acidic medium for the OER process, the high valence state Ru is very likely to react with H + to generate soluble Ru ions, resulting in the loss of active components and further leading to an irreversible decay of OER activity. In addition, the above electrocatalyst is suitable for water electrolysis in an alkaline medium.

[0032] The electrode reactions that occur in acidic medium water electrolysis and alkaline medium water electrolysis are completely different, and the roles played by electrocatalysts are also completely different. Generally, electrocatalysts used for alkaline medium water electrolysis and acidic medium water electrolysis cannot be directly transferred. Specifically, during alkaline medium water electrolysis, after the electrolytic cell is powered on, the positive electrode gains electrons, releases hydrogen, and generates hydroxide ions (OH - ), and the 0H - ions migrate from the positive electrode to the negative electrode through the electrolyte, release electrons at the negative electrode, and generate oxygen and water.

[0033] The electrolysis reaction is as follows: Positive electrode reaction: 2H 2 O + 4e - → 2H 2 + 4OH - ; In this process, the catalyst needs to have both water dissociation and H adsorption; Negative electrode reaction: 4OH - → O 2 + H 2 O + 4e - ; In this process, the catalyst is used to optimize the OH⁻ adsorption and deprotonation processes.

[0034] During acidic medium water electrolysis, protons (H + ) are generated from water at the positive electrode, oxygen and electrons are released, and the protons reach the negative electrode through the proton exchange membrane from the positive electrode and become hydrogen after obtaining electrons at the negative electrode.

[0035] The electrolysis reaction is as follows: Anode reaction: 2H 2 O → 4H + + 4e - + O 2 ; During this process, a catalyst is used on the surface to promote the dissociation of H 2 O and the formation of O-O bonds; Cathode reaction: 4H + + 4e - → 2H 2 ; During this process, the catalyst needs to efficiently adsorb H⁺ and promote the combination of H-H bonds.

[0036] Based on this, the present invention provides an electrocatalyst for electrolyzing water in a strong acidic medium - ruthenium dioxide - loaded cobalt ferrite fibers. The present invention uses sodium alginate and calcium chloride to prepare calcium alginate fibers by wet spinning, and then the calcium alginate fibers are successively reacted with hydrochloric acid and cobalt chloride and then calcined to obtain cobalt ferrite fibers, and then reacted with ruthenium trichloride and carbonized to obtain ruthenium dioxide - loaded cobalt ferrite fibers.

[0037] During the acidic OER process, the surface of the Ru - based catalyst (such as RuO 2 ) will be further oxidized to a high valence state (such as +5, +6 valence) Ru at a high potential. These high - valence Ru species are easily dissolved into the electrolyte in a strong acidic environment (such as H 2 SO 4 or HClO 4 electrolyte), resulting in irreversible loss of the active sites of the catalyst, thus leading to poor stability and low activity of the catalyst. However, the present invention uses cobalt ferrite as an electron donor, and through the transfer of electrons from Co to Ru, the oxidation state of Ru is reduced. By this electron transfer, the local electronic structure of Ru is changed, and it exists in a stable medium - low valence state. Thus, the prepared ruthenium dioxide - loaded cobalt ferrite not only improves the stability of the catalyst, but also enhances its intrinsic catalytic activity by optimizing the electronic state of Ru, thereby achieving efficient and durable OER performance in an acidic medium.

[0038] In addition, the prepared ruthenium dioxide - loaded cobalt ferrite fibers of the present invention have an obvious one - dimensional structure and abundant pores. This structure improves the contact area between the ruthenium dioxide - loaded cobalt ferrite fiber catalyst and the electrolyte, and promotes the transport of the electrolyte and the release of O 2 .

[0039] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with specific embodiments.

[0040] The experimental materials used in the embodiments of the present invention are all conventional experimental materials in the art and can be obtained through commercial channels.

[0041] Example 1: Cobalt tetroxide supported ruthenium dioxide fiber (1) After extruding a sodium alginate solution with a mass fraction of 1.0% through a spinneret, it enters a coagulation bath containing calcium chloride solution at a temperature of 30 °C and stays for 20 s to solidify and form a primary fiber; after washing the primary fiber with deionized water, it is stretched and dried to obtain a calcium alginate fiber; among them, the mass fraction of the calcium chloride solution is 4%, the linear velocity after extrusion is 12 m / min, and the draw ratio is 0.91%; Mix cobalt chloride, deionized water, and ethanol according to a material liquid ratio of 500 mg: 50 mL: 50 mL to obtain a cobalt chloride solution; after mixing the calcium alginate fiber with hydrochloric acid with a concentration of 1 mol / L, react under ultrasonic treatment for 180 min, wash with water and dry to obtain a hydrogen alginate fiber; after mixing the hydrogen alginate fiber with the cobalt chloride solution, react under ultrasonic treatment for 300 min, wash with water and dry to obtain a cobalt alginate fiber; among them, the addition amounts of cobalt chloride in the calcium alginate fiber, hydrochloric acid, and cobalt chloride solution are 1 g: 100 mL: 500 mg; Place the cobalt alginate fiber in a tubular furnace, and under an air atmosphere, heat it to 500 °C at a heating rate of 2 °C / min and keep it calcined for 2 h to obtain a cobalt tetroxide fiber; (2) After mixing the cobalt tetroxide fiber with a ruthenium trichloride solution with a mass fraction of 0.08% according to a material liquid ratio of 0.1 g: 50 mL, carry out hydrothermal reaction at 120 °C for 3 h, wash and dry to obtain a cobalt tetroxide fiber supported ruthenium precursor; Place the cobalt tetroxide fiber supported ruthenium precursor in a tubular furnace, and under an air atmosphere, heat it to 300 °C at a heating rate of 5 °C / min and keep it heat-treated for 3 h to obtain a cobalt tetroxide supported ruthenium dioxide fiber.

[0042] Perform structural characterization on the cobalt tetroxide supported ruthenium dioxide fiber prepared in this example, and the results are as Figures 1 - 4 shown.

[0043] Through Figure 1 It can be seen that the diameter of the cobalt tetroxide supported ruthenium dioxide fiber prepared in this example is about 12 μm and it has an obvious one-dimensional structure and abundant pores. From Figure 2 It can be seen that the XRD pattern of the cobalt tetroxide supported ruthenium dioxide fiber prepared in this example contains Co 3 O 4 (PDF#97 - 003 - 6256). Since the Ru content in the cobalt tetroxide supported ruthenium dioxide fiber is very small, there is no peak related to Ru in the XRD pattern. ThroughFigure 3 The HRTEM image can prove that the prepared ruthenium dioxide-loaded cobalt tetroxide fibers contain RuO 2 . Through Figure 4 it can be seen that electrons are transferred from Co to Ru, effectively inhibiting the formation and dissolution of high-valent Ru during the acidic OER process. This mechanism not only improves the stability of the catalyst but also enhances its intrinsic catalytic activity by optimizing the electronic state of Ru, thus achieving efficient and durable OER performance in acidic media.

[0044] Example 2: Ruthenium dioxide-loaded cobalt tetroxide fibers (1) After extruding a sodium alginate solution with a mass fraction of 0.8% through a spinneret, it enters a coagulation bath containing calcium chloride solution at a temperature of 25 °C and stays for 15 s to solidify and form a primary fiber; after washing the primary fiber with deionized water, it is stretched and dried to obtain calcium alginate fiber; among them, the mass fraction of the calcium chloride solution is 3.5%, the linear velocity after extrusion is 10 m / min, and the draw ratio is 0.90%; Cobalt chloride, deionized water, and ethanol are mixed evenly according to a liquid material ratio of 450 mg: 50 mL: 50 mL to obtain a cobalt chloride solution; after mixing the calcium alginate fiber with hydrochloric acid with a concentration of 0.8 mol / L, the reaction is carried out for 150 min under ultrasonic treatment, washed with water and dried to obtain hydrogen alginate fiber; after mixing the hydrogen alginate fiber with the cobalt chloride solution, the reaction is carried out for 250 min under ultrasonic treatment, washed with water and dried to obtain cobalt alginate fiber; among them, the addition amount of cobalt chloride in the calcium alginate fiber, hydrochloric acid, and cobalt chloride solution is 0.8 g: 100 mL: 500 mg; The cobalt alginate fiber is placed in a tubular furnace, and under an air atmosphere, it is heated to 450 °C at a heating rate of 1 °C / min and calcined for 2.5 h to obtain cobalt tetroxide fiber; (2) After mixing the cobalt tetroxide fiber with a ruthenium trichloride solution with a mass fraction of 0.05% according to a liquid material ratio of 0.08 g: 50 mL, the hydrothermal reaction is carried out at 110 °C for 3.5 h, washed and dried to obtain a ruthenium precursor-loaded cobalt tetroxide fiber; The ruthenium precursor-loaded cobalt tetroxide fiber is placed in a tubular furnace, and under an air atmosphere, it is heated to 250 °C at a heating rate of 3 °C / min and heat-treated for 3.5 h to obtain ruthenium dioxide-loaded cobalt tetroxide fiber.

[0045] Example 3: Ruthenium dioxide-loaded cobalt tetroxide fibers (1) After extruding the sodium alginate solution with a mass fraction of 1.2% through a spinneret, it enters a coagulation bath containing calcium chloride solution at a temperature of 35 °C and stays for 25 s to solidify and form a primary fiber; after washing the primary fiber with deionized water, it is stretched and dried to obtain calcium alginate fiber; among them, the mass fraction of the calcium chloride solution is 4.5%, the linear velocity after extrusion is 15 m / min, and the draw ratio is 0.92%; Cobalt chloride, deionized water and ethanol are mixed evenly according to the material ratio of 550 mg: 50 mL: 50 mL to obtain cobalt chloride solution; after mixing calcium alginate fiber with hydrochloric acid with a concentration of 1.2 mol / L, the reaction is carried out for 200 min under ultrasonic treatment, washed with water and dried to obtain hydrogen alginate fiber; after mixing hydrogen alginate fiber with cobalt chloride solution, the reaction is carried out for 350 min under ultrasonic treatment, washed with water and dried to obtain cobalt alginate fiber; among them, the addition amounts of calcium alginate fiber, hydrochloric acid and cobalt chloride in the cobalt chloride solution are 1.2 g: 100 mL: 500 mg; Place the cobalt alginate fiber in a tubular furnace, and under an air atmosphere, heat it to 550 °C at a heating rate of 3 °C / min and keep it calcined for 1.5 h to obtain cobalt tetroxide fiber; (2) After mixing the cobalt tetroxide fiber with ruthenium trichloride solution with a mass fraction of 0.10% according to the material ratio of 0.12 g: 50 mL, carry out hydrothermal reaction at 130 °C for 2.5 h, wash and dry to obtain cobalt tetroxide fiber loaded with ruthenium precursor; Place the cobalt tetroxide fiber loaded with ruthenium precursor in a tubular furnace, and under an air atmosphere, heat it to 350 °C at a heating rate of 6 °C / min and keep it for 2.5 h to obtain cobalt tetroxide supported ruthenium dioxide fiber.

[0046] Comparative Example 1: Ruthenium dioxide electrocatalyst Place the ruthenium trichloride solution with a mass fraction of 0.08% in a tubular furnace, and under an air atmosphere, heat it to 300 °C at a heating rate of 5 °C / min and keep it for 3 h to obtain ruthenium dioxide electrocatalyst.

[0047] Comparative Example 2: Cobalt tetroxide fiber electrocatalyst After extruding the sodium alginate solution with a mass fraction of 1.0% through a spinneret, it enters a coagulation bath containing calcium chloride solution at a temperature of 30 °C and stays for 20 s to solidify and form a primary fiber; after washing the primary fiber with deionized water, it is stretched and dried to obtain calcium alginate fiber; among them, the mass fraction of the calcium chloride solution is 4%, the linear velocity after extrusion is 12 m / min, and the draw ratio is 0.91%; Mix cobalt chloride, deionized water, and ethanol according to a material ratio of 500 mg: 50 mL: 50 mL to obtain a cobalt chloride solution; mix calcium alginate fiber with hydrochloric acid at a concentration of 1 mol / L, react under ultrasonic treatment for 180 min, wash with water and dry to obtain hydrogen alginate fiber; mix hydrogen alginate fiber with cobalt chloride solution, react under ultrasonic treatment for 300 min, wash with water and dry to obtain cobalt alginate fiber; among them, the addition amounts of calcium alginate fiber, hydrochloric acid, and cobalt chloride in the cobalt chloride solution are 1 g: 100 mL: 500 mg; Place the cobalt alginate fiber in a tubular furnace, heat it to 500 °C at a heating rate of 2 °C / min under an air atmosphere, and keep it calcined for 2 h to obtain a cobalt tetroxide fiber electrocatalyst.

[0048] Test Example 1: Electrochemical performance test Detect the electrochemical performance of the materials prepared in Example 1 and Comparative Examples 1-2 and commercial RuO 2 The specific steps are as follows: Weigh 3 mg of the catalysts prepared in Example 1 and Comparative Examples 1-2 respectively, disperse them in 330 μL of Nafion / ethanol mixed solution, and perform ultrasonic treatment for 30 min to obtain a catalyst suspension; polish and grind the glassy carbon electrode and dry it naturally, take 8 μL of the catalyst suspension and drop it onto the glassy carbon electrode with an area of 0.196 cm² and dry it at room temperature; Place the prepared catalyst in a standard three-electrode system to test its electrochemical performance. Among them, the electrolyte is 0.1 M HClO 4 , a platinum wire, a glassy carbon electrode, and a standard hydrogen electrode are used as the counter electrode, working electrode, and reference electrode respectively, and the OER activity of the catalyst is tested by the LSV method. The results are as Figure 5 shown. Among them, the scanning rate of the LSV polarization curve is 5 mV / s, and the catalyst loading is 0.417 mg / cm²; then, the stability of the ruthenium dioxide-loaded cobalt tetroxide fiber prepared in Example 1 as a catalyst is tested by a 100 h v-t test. The results are as Figure 6 shown; during the test process, in the OER performance detection, the potential range is above 1.1 V vs RHE, and the LSV scanning direction is positive.

[0049] It can be seen from Figure 5 that in 0.1 M HClO 4 electrolyte at a current density of 10 mA / cm 2 the overpotential of the ruthenium dioxide-loaded cobalt tetroxide fiber prepared by the present invention is 220 mV. While the reference catalyst commercial RuO 2The overpotential was 320 mV, and the overpotential of the cobalt tetroxide fiber prepared in Comparative Example 2 was 400 mV. It can be seen that the ruthenium dioxide-loaded cobalt tetroxide fiber prepared in the present invention has good OER activity as a catalyst.

[0050] It can be seen from Figure 6 that the ruthenium dioxide-loaded cobalt tetroxide fiber prepared in the present invention has a substantially unchanged voltage after being tested in 0.1 M HClO 4 electrolyte for 100 h. It can be seen that the ruthenium dioxide-loaded cobalt tetroxide fiber has excellent catalytic stability.

[0051] Test Example 2: Electrolytic water test The electrolytic water performance of the ruthenium dioxide-loaded cobalt tetroxide electrocatalyst prepared in Example 1 was detected. The specific steps were as follows: The OER performance of the electrolytic simulated seawater and seawater of the catalyst prepared in Experimental Example 1 was tested in a three-electrode system, and the electrolytes were simulated seawater and seawater respectively. Among them, the simulated seawater was prepared by mixing 0.01 M HClO 4 and 0.58 M NaCl in a volume ratio of 2:1; the seawater was prepared by mixing 0.01 M HClO 4 and natural seawater in a volume ratio of 1:1.

[0052] A platinum wire, a glassy carbon electrode, and a standard hydrogen electrode were used as the counter electrode, working electrode, and reference electrode respectively, and the LSV method was used to test its OER activity as a catalyst. Among them, the scanning rate of the LSV polarization curve was 5 mV / s, and the loading amount of the catalyst was 0.417 mg / cm². During the test, in the OER performance detection, the potential range was above 1.1 V vs RHE, and the LSV scanning direction was positive. The detection results were as Figures 7 - 8 shown.

[0053] It can be seen from Figure 7 that the voltage of the ruthenium dioxide-loaded cobalt tetroxide fiber obtained in this example for electrolyzing simulated seawater at a current density of 10 mA / cm 2 was 1.43 V. It can be seen from Figure 8 that the voltage of the ruthenium dioxide-loaded cobalt tetroxide fiber obtained in this example for electrolyzing seawater at a current density of 10 mA / cm 2 was 1.44 V.

[0054] The above are only the preferred embodiments of the present application and are not used to limit the present application. For those skilled in the art, various changes and modifications can be made to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing cobalt tetroxide-loaded ruthenium dioxide fiber, characterized in that: The following steps are involved: (1) Sodium alginate and calcium chloride solution are used as raw materials, and calcium alginate fibers are obtained by wet spinning; the calcium alginate fibers are mixed with hydrochloric acid to react to obtain hydrogen alginate fibers; the hydrogen alginate fibers are mixed with cobalt chloride solution to react to obtain cobalt alginate fibers; the cobalt alginate fibers are calcined to obtain cobalt tetroxide fibers; (2) Cobalt tetroxide fiber and ruthenium trichloride solution are mixed and subjected to hydrothermal reaction to obtain a cobalt tetroxide fiber-loaded ruthenium precursor; and the cobalt tetroxide fiber-loaded ruthenium precursor is carbonized to obtain cobalt tetroxide-loaded ruthenium dioxide fiber.

2. The method for preparing cobalt tetroxide-loaded ruthenium dioxide fiber according to claim 1, characterized in that: In step (1), the mass fraction of the sodium alginate solution is 0.8%-1.2%; the mass fraction of the calcium chloride solution is 3.5%-4.5%, the concentration of hydrochloric acid is 0.8-1.2 mol / L, and the cobalt chloride solution is prepared by mixing cobalt chloride, water and ethanol in a solid-liquid ratio of (450-550) mg:50 mL:50 mL.

3. The method for preparing cobalt tetroxide-loaded ruthenium dioxide fiber according to claim 1, characterized in that: The specific steps of wet spinning are: extruding sodium alginate solution through a spinneret and then entering a coagulation bath containing calcium chloride solution to coagulate and form primary fibers; washing the primary fibers with water, stretching and drying them to obtain calcium alginate fibers; The residence time of the sodium alginate solution in the coagulation bath after being extruded through the spinneret is 15-25 seconds, and the temperature of the coagulation bath is 25-35° C.; the linear speed of the sodium alginate solution after being extruded through the spinneret is 10-15 m / min; and the draft ratio is 0.90-0.92%.

4. The method for preparing cobalt tetroxide-loaded ruthenium dioxide fiber according to claim 1, characterized in that: In step (1), the addition ratio of calcium alginate fiber, hydrochloric acid, and cobalt chloride in the cobalt chloride solution is (0.8-1.2) g: 100 mL: 500 mg; The reaction time of calcium alginate fiber and hydrochloric acid is 150-200 minutes, and the reaction time of hydrogen alginate fiber and cobalt chloride solution is 250-350 minutes.

5. The method for preparing cobalt tetroxide-loaded ruthenium dioxide fiber according to claim 1, characterized in that: In step (1), the specific operation of calcination is: placing the cobalt alginate fiber in an air atmosphere, heating it to 450-550° C. at a heating rate of 1-3° C. / min, and then calcining it for 1.5-2.5 hours.

6. The method for preparing cobalt tetroxide-loaded ruthenium dioxide fiber according to claim 1, characterized in that: In step (2), the mass fraction of the ruthenium trichloride solution is 0.08%-0.10%; the added amount of the cobalt tetroxide fiber and the ruthenium trichloride solution is (0.08-0.12) g: 50 mL.

7. The method for preparing cobalt tetroxide-loaded ruthenium dioxide fiber according to claim 1, characterized in that: In step (2), the hydrothermal reaction temperature is 110-130°C, and the hydrothermal reaction time is 2.5-3.5h; The specific operation of carbonization is: placing the cobalt tetroxide fiber loaded with ruthenium precursor in an air atmosphere, heating it to 250-350°C at a heating rate of 3-6°C / min, and keeping it warm for 2.5-3.5h.

8. Cobalt tetroxide-loaded ruthenium dioxide fiber prepared by the preparation method according to any one of claims 1 to 7.

9. Use of the cobalt tetroxide-loaded ruthenium dioxide fiber according to claim 8 in electrolysis of water or seawater in an acidic medium.

10. The use according to claim 9, characterized in that The acidic medium is a HClO4 solution with a concentration of 0.05-0.15M.

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