Transition metal anchored heteroatom doped RuO2 fiber aerogel electrocatalyst as well as preparation method and application thereof

Abstract

The invention discloses a transition metal anchored heteroatom doped RuO2 fiber aerogel electrocatalyst and a preparation method and application thereof.The preparation method includes the steps that RuO2 fibers are prepared through an electrostatic spinning technology to serve as a catalytic substrate, and transition metal nanoparticles are anchored to a continuous conductive network formed by the RuO2 fibers through a metal self-organization technology; finally, one-dimensional fibers are recombined into a three-dimensional graded porous aerogel structure through a freeze drying technology, an efficient channel is provided for electrolyte mass transfer and gas product escape, and uniform distribution and full exposure of active sites are achieved. Wherein the transition metal nanoparticles are converted into M-OH in situ in the OER process, and then a deprotonation reaction is carried out to form a Lewis acid layer. Doped heteroatoms can be oxidized in an alkaline environment to form anion groups with negative electricity, and Cl <-> erosion can be effectively resisted through a charge repulsion effect. By establishing a Lewis acid-anionic charge repulsion dual corrosion-resistant mechanism, the bottleneck of poor stability of the catalyst in a seawater high-salt environment can be broken through.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of aerogel materials, and particularly relates to a transition metal-anchored heteroatom-doped RuO2 fiber aerogel electrocatalyst, a preparation method thereof, and application thereof in electrolysis of seawater to produce hydrogen. BACKGROUND

[0002] Electrolysis of water is an important technology for producing hydrogen and renewable energy conversion and collection, and its essence is that under the driving of direct current, water molecules generate H2 (HER) through hydrogen evolution reaction at the cathode, and generate O2 (OER) through oxygen evolution reaction at the anode. The mature low-temperature electrolysis route at the present stage all uses high-purity water as raw material. If future large-scale hydrogen production will compete with agriculture and industry for limited fresh water resources, a new distribution crisis will be caused. Seawater accounts for 96.5% of the earth's water reserves and is naturally rich in ions, which can directly serve as an electrolyte and is theoretically inexhaustible raw material. However, the natural seawater system is complex, involving microorganisms and organic matter polluting the electrode surface, high concentration of Cl - (≈0.55 mol L - ¹) competes to evolve Cl2 at the anode, and corrodes the catalytic sites and Mg 2+ / Ca 2+ ions are easy to deposit and cause blockage of the pores. These factors make direct seawater electrolysis still in the laboratory exploration stage. To move towards industrialization, electrocatalysts with high activity, long service life and strong corrosion resistance must be developed.

[0003] Aerogel material is a kind of nanomaterial with structural characteristics of low density, high specific surface area, high porosity and high pore volume, which has received extensive attention in the fields of thermal insulation, adsorption, catalysis and sensing. The skeleton of nanofiber aerogel is composed of interconnected fibers, which can form a continuous electron transport path, reducing the charge transfer resistance of the catalytic reaction. RuO2 is a relatively low-cost noble metal oxide, which is the most suitable catalyst for industrial application due to its high intrinsic activity, high conductivity and strong environmental tolerance. Although RuO2 has been widely studied in the field of electrocatalytic water splitting, Ru 4+ tends to transform into unstable soluble Ru n+ > 4+ in the OER process, resulting in easy dissolution and deactivation of the catalyst. The common strategies to improve the stability of RuO2 at present include mixing RuO2 with more corrosion-resistant materials and controlling the dispersion of RuO2 to avoid direct contact with the electrolyte. Du (Nature Communications, 2022, 13, 5448) and others were inspired by the use of sacrificial components to protect target materials, and constructed a RuO2 / CoO x hybrid catalyst. CoO x is oxidized as a sacrificial component, ensuring the stability of RuO2 / CoOx Liu (ACS Nano, 2025, 19, 2715-2725) et al. designed S-doped RuO2 nanosheets, which exhibited ultra-low overpotentials (25 mV (HER) and 243 mV (OER)) in seawater splitting and maintained 1000 h durability. In addition, experimental and theoretical studies have shown that the high protection of surface S doping can reduce the high oxidation state of Ru, and the anion passivation of S effectively repels Cl - protect RuO2 from corrosion. However, the currently reported RuO2-based electrocatalysts are mainly one-dimensional (CN 118910669A) or two-dimensional (CN 118919748B) structures. In order to further improve the specific surface area to expose more active sites, and to solve the problem of easy over-oxidation and corrosion of RuO2-based catalysts, it is of great significance to invent RuO2-based catalysts with three-dimensional porous network structure based on chemical protection mechanism. SUMMARY

[0004] The technical problem to be solved by the present application is to overcome the shortcomings of the prior art. The present application adopts electrospinning combined with metal self-assembly and freeze-drying technology to design a transition metal-anchored heteroatom-doped RuO2 fiber aerogel electrocatalyst and its preparation method. The three-dimensional porous structure is used to improve mass transfer and electron conduction, and the Lewis acid sites are combined with anion layers to resist Cl - erosion, thereby significantly improving the catalytic activity and stability.

[0005] To achieve the above purpose, the technical solution adopted by the present application is as follows: The preparation method of the transition metal-anchored heteroatom-doped RuO2 fiber aerogel electrocatalyst comprises the following steps: S1, dissolving a polymer, a ruthenium salt and a non-metallic compound in a polar solvent, and fully stirring to obtain a spinning solution; S2, preparing a flexible precursor nanofiber membrane by electrospinning the spinning solution obtained in step S1; S3, calcining the flexible precursor nanofiber membrane obtained in step S2 to obtain a heteroatom-doped RuO2 nanofiber; S4, ultrasonic dispersion of the heteroatom-doped RuO2 nanofiber prepared in step S3 in deionized water to obtain a dispersion solution containing nanofibers, then dissolving a transition metal salt and an organic ligand in the solution, stirring and mixing uniformly at room temperature, then slowly adding a reducing agent and stirring and mixing to prepare a gel precursor solution; S5, the gel precursor solution prepared in step S4 is placed at 25-55 °C for 1.0-6.0 h to obtain a wet gel; S6, the wet gel obtained in step S5 is subjected to aging treatment, and is washed with deionized water multiple times during the treatment, and is finally subjected to freeze-drying treatment.

[0006] Specifically, in step S1, the polymer is selected from any one of polyvinylpyrrolidone, polyacrylonitrile, polyamide, polyvinyl alcohol, and polyvinyl butyral; The ruthenium salt is selected from any one of ruthenium chloride trihydrate, potassium hexachlororuthenate, ruthenium acetate, trispyridine ruthenium chloride hexahydrate, and ruthenocene; The non-metallic compound is selected from any one of a nitrogen-containing compound, a phosphorus-containing compound, a sulfur-containing compound, and a boron-containing compound; the nitrogen-containing compound is any one of ethylenediamine, urea, melamine, hydrazine hydrate, and propionitrile; the phosphorus-containing compound is any one of phytic acid, phosphoric acid, diammonium hydrogen phosphate, sodium hypophosphite, and triphenylphosphine; the sulfur-containing compound is any one of thiophene, thiourea, sulfuric acid, thioacetamide, and mercaptan; and the boron-containing compound is any one of boric acid, diboron trioxide, trimethyl borate, sodium tetraphenylborate, and boron trichloride; The polar solvent is selected from any one of dimethylformamide, ethanol, acetone, chloroform, formic acid, and hexafluoroisopropanol or a mixture of two or more thereof.

[0007] Specifically, in step S1, the mass ratio of the polymer, the ruthenium salt, the non-metallic compound, and the polar solvent is (5-20):(5-20):(1-2):(50-300); the stirring temperature is controlled at 20-40 °C, and the stirring time is 8-16 h; preferably, the stirring speed in step (1) is 400-800 r / min.

[0008] Specifically, in step S2, the spinning solution is loaded into a syringe, and the distance between the needle tip of the syringe and the aluminum foil collector is 10-30 cm during electrospinning, and the advancing rate and the electric field voltage are set to be 0.10-0.80 mL / h and 14-20 kV, respectively.

[0009] Specifically, in step S3, the calcination temperature is 400-700 °C, the temperature rising speed is 2-6 °C / min, and the holding time is 2-7 h.

[0010] Specifically, in step S4, the mass ratio of the heteroatom-doped RuO2 nanofiber and deionized water is (1-20):(200-500); the transition metal salt, the organic ligand, and the reducing agent are mixed in a molar concentration of (2-25 mmol / L):(0.0002-0.0075 mmol / L):(2-50 mmol / L), respectively.

[0011] Preferably, the transition metal salt and the organic ligand are added into the solution containing nanofibers, stirred at 20-40℃ for 20-60 min to make them uniformly mixed, then the reducing agent is slowly added into the solution and stirred for 10-30 min to prepare the gel precursor solution; the stirring speed is 200-800 r / min.

[0012] Specifically, in step S4, the transition metal salt is selected from any one of copper salt, nickel salt, cobalt salt, manganese salt, iron salt, chromium salt and molybdenum salt. The copper salt is one of copper chloride trihydrate, copper nitrate pentahydrate, copper sulfate pentahydrate and copper carbonate. The nickel salt is one of nickel chloride hexahydrate, nickel nitrate hexahydrate, nickel sulfate hexahydrate and nickel nitrite. The cobalt salt is one of cobalt chloride hexahydrate, cobalt acetate tetrahydrate, cobalt sulfate heptahydrate and cobalt nitrate hexahydrate. The manganese salt is one of manganese chloride tetrahydrate, manganese sulfate monohydrate, manganese nitrate tetrahydrate and manganese carbonate. The iron salt is one of iron chloride hexahydrate, iron nitrate nonahydrate, iron sulfate nonahydrate, ferrous sulfate heptahydrate and iron carbonate. The chromium salt is one of chromium chloride hexahydrate, chromium nitrate nonahydrate, sodium chromate, ammonium chromate and sodium dichromate. The molybdenum salt is one of sodium molybdate dihydrate, ammonium molybdate tetrahydrate, sodium hydrogen molybdate, ammonium chromate and sodium dichromate.

[0013] Specifically, in step S4, the organic ligand is any one of sodium citrate, sodium tartrate, cysteine, lysine, mercaptoalkanoic acid and ethylenediaminetetraacetic acid; and the reducing agent is any one of sodium borohydride, potassium borohydride, ascorbic acid, glucose and citric acid.

[0014] Preferably, in step S5, the gel precursor solution is placed at 25-55℃ for 1.0-6.0 h to obtain a black wet gel.

[0015] Preferably, in step S6, the deionized water is used for washing 4-9 times during the aging treatment, and the interval time is 3-12 h.

[0016] Preferably, in step S7, the wet gel after washing is frozen in liquid nitrogen for 5-30 min, and then subjected to freeze-drying treatment; the freeze-drying temperature is -60--20℃, and the drying time is 8-48 h.

[0017] Further, the transition metal-anchored heteroatom-doped RuO2 fiber aerogel electrocatalyst prepared by the above preparation method is also within the protection scope of the present application.

[0018] Further, the application also claims the application of the above-mentioned transition metal anchor heteroatom-doped RuO2 fiber aerogel electrocatalyst in electrolysis of seawater for hydrogen production.

[0019] The application adopts electrospinning combined with metal self-assembly and freeze-drying technology to design a preparation method of a fiber aerogel electrocatalyst based on Lewis acid-anion charge repulsion synergistic protection for the field of electrocatalysis, realizes high-efficiency OER / HER catalytic performance, and breaks through the bottleneck of poor stability of seawater electrolysis hydrogen production catalyst. In the application, RuO2 fibers with high intrinsic activity and high conductivity are prepared by electrospinning as a catalytic substrate, and then transition metal nanoparticles are uniformly anchored on the continuous conductive network formed by the RuO2 fibers through self-organization technology. Finally, the one-dimensional fibers are reorganized into a three-dimensional hierarchical porous aerogel structure through ice crystal directional growth combined with freeze-drying technology, which provides efficient channels for electrolyte mass transfer and gas product escape, and realizes the exposure of a large number of active sites by increasing the specific surface area. In the OER process in an alkaline environment, water molecules are adsorbed on the metal surface and hydroxylation occurs, forming high-valence metal hydroxide (M-OH). With the increase of potential, M-OH further undergoes deprotonation reaction to generate a negatively charged oxygen species (M-O - ), which makes the surface metal atoms have a more unsaturated coordination environment, and their ability to accept electron pairs (i.e. Lewis acidity) is significantly enhanced. The in-situ formed Lewis acid layer will be more inclined to adsorb OH - , while strongly repelling Cl - . In addition, the Lewis acid layer and RuO2 synergistically regulate the electronic structure, significantly improve the reaction kinetics, and inhibit the over-oxidation of Ru n+ , thereby avoiding catalyst deactivation. At the same time, to further solve the problem that the active species of traditional catalysts are easily eroded, the doped heteroatoms can be oxidized to form negatively charged anion groups in an alkaline environment, which effectively resist Cl - erosion through the charge repulsion effect. By reconstructing Lewis acid sites and anion protection layers on the surface, a dual anti-corrosion mechanism is established, and a fiber aerogel electrocatalyst is constructed, which can break through the bottleneck of poor stability of catalysts in high-salinity seawater. The application aims at the three major pain points (insufficient catalyst activity, serious Cl - corrosion, and low mass transfer efficiency) of seawater electrolysis for hydrogen production. The OER / HER activity is improved through multi-component coupling (RuO2 / M-OH synergistic catalysis), the mass transfer and electron conduction are improved by means of three-dimensional porous structure, and the Lewis acid sites and anion layer are used to resist Cl - erosion, thereby significantly improving the catalytic activity and stability, which has important significance for the industrialization of renewable energy large-scale hydrogen production.

[0020] Compared with the prior art, the application has the following advantages: (1) The preparation process of the application is simple, low in cost and low in energy consumption. The RuO2 fiber with adjustable diameter is prepared by using the continuous production electrospinning technology, the content of noble metal RuO2 in the catalyst is reduced, and the RuO2 fiber is obtained by the low-cost and simple process freeze-drying technology, which is suitable for large-scale preparation.

[0021] (2) The application provides a novel design idea, and a composite structure of a heteroatom-doped RuO2 fiber skeleton combined with transition metal nanoparticles / anion protective layer is prepared, and through the synergistic effect of multiple components, high OER / HER catalytic activity is realized. The RuO2 has high conductivity and high catalytic activity, and the unique electronic structure can optimize the adsorption energy of the reaction intermediate, and improve the reaction kinetic speed. When the RuO2 exists in the form of fibrous aerogel structure, the high specific surface area and the continuous conductive network further strengthen the exposure of active sites and the charge transport efficiency. Secondly, when the transition metal nanoparticles anchored on the surface are in-situ converted into M-OH during the OER process, and further deprotonation reaction is carried out to form a Lewis acid layer, which can synergistically regulate the electronic structure with RuO2, and at the same time, the Cl - strong electrostatic repulsion. In addition, the heteroatom is in-situ restructured to form an anion protective layer, which can efficiently repel Cl - , and avoid the corrosion of the catalytic site. Based on the dual anti-corrosion mechanism of Lewis acid-anion charge repulsion, the fibrous aerogel electrocatalyst is constructed, which solves the problem of Cl - corrosion in seawater splitting, improves the catalytic performance of electrolytic seawater, and has excellent stability and durability.

[0022] (3) The transition metal-anchored heteroatom-doped RuO2 fibrous aerogel electrocatalyst prepared by the application can form an in-situ reconstitution and charge repulsion protective layer in the electrolytic seawater hydrogen production, and produce a dual anti-corrosion mechanism based on the synergistic protection of Lewis acid-anion charge repulsion, which provides a new idea for the synergistic design of active species regulation and corrosion protection in heterogeneous catalysis, which has a positive significance for the application basic research of electrocatalytic materials in complex media (such as seawater and high-salinity wastewater). BRIEF DESCRIPTION OF DRAWINGS

[0023] The above and / or other aspects of the application will become more apparent by describing in detail the preferred embodiments thereof with reference to the attached drawings.

[0024] Figure 1 is the XRD spectrum of the Cu-N / RuO2 fibrous aerogel prepared in Example 1.

[0025] Figure 2 is the SEM electron microscope graph of the Ni-B / RuO2 fibrous aerogel prepared in Example 2.

[0026] Figure 3 Figure 1 is the test data of the fiber aerogels made by the embodiments in the electrolysis of seawater to produce hydrogen. Wherein (a) is the OER polarization curve of the fiber aerogels made in Example 1, Example 2, Example 3, Example 4, and Example 5 in the alkaline seawater, (b) is the OER polarization curve of the fiber aerogels made in Example 1, Example 2, Example 3, Example 4, and Example 5 in the alkaline seawater, (c) is the potentiodynamic polarization curve of CoCr-P / RuO2 made in Example 6, (d) is the potentiostatic polarization curve of the fiber aerogels made in Example 1 and Example 2, (e) is the polarization curve of the fiber aerogels made in Example 3, Example 4, Example 5, Example 6, and Example 7 applied in the anion exchange membrane water electrolysis cell, (f) is the durability test of CoCr-P / RuO2 made in Example 6 at 100 mA·cm-2current density, (g) is the electrochemical in-situ Raman spectrum of CoCr-P / RuO2 made in Example 6. -2 Figure 1 is the test data of the fiber aerogels made by the embodiments in the electrolysis of seawater to produce hydrogen. Wherein (a) is the OER polarization curve of the fiber aerogels made in Example 1, Example 2, Example 3, Example 4, and Example 5 in the alkaline seawater, (b) is the OER polarization curve of the fiber aerogels made in Example 1, Example 2, Example 3, Example 4, and Example 5 in the alkaline seawater, (c) is the potentiodynamic polarization curve of CoCr-P / RuO2 made in Example 6, (d) is the potentiostatic polarization curve of the fiber aerogels made in Example 1 and Example 2, (e) is the polarization curve of the fiber aerogels made in Example 3, Example 4, Example 5, Example 6, and Example 7 applied in the anion exchange membrane water electrolysis cell, (f) is the durability test of CoCr-P / RuO2 made in Example 6 at 100 mA·cm-2current density, (g) is the electrochemical in-situ Raman spectrum of CoCr-P / RuO2 made in Example 6. DETAILED DESCRIPTION

[0027] The present application can be better understood according to the following examples. Example 1

[0028] A homogeneous spinning solution was prepared by dissolving 0.1 g of polyacrylonitrile, 0.1 g of ruthenium acetate and 0.02 g of urea in 1 g of dimethylformamide at 20 °C with stirring at 400 r / min for 8 h. The spinning solution was loaded into a syringe, and a flexible precursor nanofiber membrane was prepared by electrospinning technology, with the distance between the needle tip and the aluminum foil collector set to 10 cm, the push rate and the electric field voltage set to 0.10 mL / h and 14 kV, respectively. The nanofiber membrane was then placed in a muffle furnace for calcination at 400 °C, with a heating rate of 2 °C / min and a holding time of 6 h, to obtain N-doped RuO2 nanofibers. 10 mg of the nanofibers were ultrasonically dispersed in deionized water (mass ratio of 1:200). Subsequently, 4 mmol of copper chloride trihydrate and 0.0002 mmol of sodium tartrate were dissolved in the solution containing the nanofibers, and stirred at 20 °C at 400 r / min for 20 min to mix uniformly. Then, 20 mmol of ascorbic acid was slowly added and stirred at 400 r / min for 10 min to prepare a gel precursor solution. The co-precursor solution was left to stand at 25 °C for 5.0 h to obtain a black wet gel. The wet gel obtained above was then subjected to aging treatment, with solvent replacement using deionized water for 9 times at an interval of 3 h each time. The replaced wet gel was frozen in liquid nitrogen for 5 min, and then subjected to freeze-drying treatment, with a drying temperature of -30 °C and a drying time of 18 h, to finally obtain Cu-anchored N-doped RuO2 fiber aerogel. The density of the material was 0.06 g / cm 3 , Figure 1 The XRD pattern of the prepared Cu-N / RuO2 fiber aerogel is shown in FIG. 6, and the diffraction peaks show that the material is a crystalline rutile RuO2. Electrochemical tests (FIG. 7) show that in alkaline seawater, the overpotential of the catalyst is 215 mV (OER) and 28 mV (HER) (a, b), and in the three-electrode device for OER, the catalytic performance does not significantly decay within 500 h (c, d), which is significantly better than that of a commercial RuO2 catalyst. Figure 3 Figure 3 a、 Figure 3 b Figure 3 d Example 2

[0029] ​A uniform spinning solution was prepared by dissolving 0.1 g of polyvinylpyrrolidone, 0.07 g of ruthenium chloride trihydrate and 0.12 g of boric acid in a mixed solution of 0.5 g of ethanol and 1 g of dimethylformamide, and stirring at 25 °C at 500 r / min for 10 h. The spinning solution was loaded into a syringe, and a flexible precursor nanofiber membrane was prepared by electrospinning technology, with the distance between the needle tip and the aluminum foil collector set to 15 cm, the push rate and the electric field voltage set to 0.35 mL / h and 15.5 kV, respectively. Then the nanofiber membrane was placed in a muffle furnace for calcination at 500 °C, with a heating rate of 3 °C / min and a holding time of 5.0 h, to obtain B-doped RuO2 nanofibers. 15 mg of nanofibers were ultrasonically dispersed in deionized water (mass ratio of 5:300). Then 9 mmol of nickel chloride hexahydrate and 0.0009 mmol of sodium citrate were dissolved in the solution containing the nanofibers, and stirred at 25 °C at 500 r / min for 40 min to mix uniformly, and then 28 mmol of sodium borohydride was slowly added and stirred at 500 r / min for 15 min to prepare a gel precursor solution. The co-precursor solution was left to stand at 35 °C for 3.0 h to obtain a black wet gel. Then the wet gel obtained above was subjected to aging treatment, and deionized water was used for solvent replacement 6 times with an interval of 5 h; the replaced wet gel was frozen in liquid nitrogen for 10 min, and then the frozen wet gel was subjected to freeze-drying treatment, with a drying temperature of -40 °C and a drying time of 20 h, to finally obtain Ni-anchored B-doped RuO2 fiber aerogel. Figure 2 For the SEM image of the prepared Ni-B / RuO2 fiber aerogel, it can be seen that the diameter of the RuO2 fiber is about 100 nm, and the pore size is mainly composed of macropores larger than 100 nm and a small amount of mesopores. Metal nanoparticles with a particle size of about 30 nm are uniformly anchored on the RuO2 fiber. According to electrochemical tests ( Figure 3 ), the overpotential of the catalyst is 210 mV (OER) and 32 mV (HER) in alkaline seawater ( Figure 3 a, Figure 3 b), and the catalytic performance in the three-electrode device for OER does not significantly decrease within 300 h ( Figure 3 d), which is significantly better than that of the commercial Pt / C catalyst. Example 3

[0030] A homogeneous spinning solution was prepared by dissolving 0.12 g of polyamide, 0.14 g of ruthenium acetate and 0.012 g of thiourea in a mixed solution of 1.11 g of acetone and 1.11 g of dimethylformamide, and stirring at 550 r / min for 12 h at 28 °C. The spinning solution was loaded into a syringe, and a flexible precursor nanofiber membrane was prepared by electrospinning technology, with a distance of 18 cm between the needle tip and the aluminum foil collector, a pushing rate of 0.5 mL / h and an electric field voltage of 16.5 kV. Then the nanofiber membrane was placed in a muffle furnace for calcination at 600 °C, with a heating rate of 5 °C / min and a holding time of 3.5 h, to obtain S-doped RuO2 nanofibers. 20 mg of the nanofibers were ultrasonically dispersed in deionized water (mass ratio of 10:350). Then 9 mmol of cobalt sulfate heptahydrate, 9 mmol of ferric nitrate nonahydrate and 0.028 mmol of sodium citrate were dissolved in the solution containing the nanofibers, and stirred at 550 r / min for 40 min at 30 °C to mix uniformly. Then 400 mM of glucose was slowly added and stirred at 550 r / min for 15 min to prepare a gel precursor solution. The co-precursor solution was left to stand at 40 °C for 5.0 h to obtain a black wet gel. Then the wet gel obtained above was subjected to aging treatment, and deionized water was used for solvent replacement for 5 times with an interval of 8 h. The replaced wet gel was frozen in liquid nitrogen for 20 min, and then the frozen wet gel was subjected to freeze-drying treatment, with a drying temperature of -45 °C and a drying time of 30 h, to finally obtain CoFe anchored S-doped RuO2 fiber aerogel. The prepared CoFe-S / RuO2 fiber aerogel has a density of 0.064 g / cm 3 , and a BET specific surface area of 50 m 2 / g. Electrochemical tests (CV) show that the overpotential of the catalyst is 220 mV (OER) and 33 mV (HER) in alkaline seawater (a, Figure 3 Figure 3 a、 Figure 3 b). When the CoFe-S / RuO2 fiber aerogel is used as the catalyst for the cathode and anode of an electrolytic water tank with an anion exchange membrane, the current density of the electrolytic tank reaches 1.1 A / cm 2 Figure 3 e) at a voltage of 2 V, and the highest battery efficiency reaches 78.2 %, showing excellent catalytic performance. Example 4

[0031] ​​A homogeneous spinning solution was obtained by dissolving 0.15 g of polyvinyl alcohol, 0.125 g of trispyridine ruthenium chloride hexahydrate and 0.013 g of trimethyl borate in 2.3 g of chloroform, and stirring at 32 °C at 600 r / min for 14 h. The spinning solution was loaded into a syringe, and a flexible precursor nanofiber membrane was prepared by electrospinning technology, with the distance between the needle tip and the aluminum foil collector set to 24 cm, the push rate and the electric field voltage set to 0.65 mL / h and 18.0 kV, respectively. Then the nanofiber membrane was placed in a muffle furnace for calcination at 650 °C, with a heating rate of 5 °C / min and a holding time of 4.0 h, to obtain B-doped RuO2 nanofibers. 30 mg of the nanofibers were ultrasonically dispersed in deionized water (mass ratio 15:400). Subsequently, 16 mmol of manganese chloride tetrahydrate and 0.04 mmol of mercaptoalkanoic acid were dissolved in the solution containing the nanofibers, and stirred at 35 °C at 600 r / min for 50 min to mix uniformly, and then 360 mmol of potassium borohydride was slowly added thereto and stirred at 600 r / min for 30 min to prepare a gel precursor solution. The co-precursor solution was left to stand at 50 °C for 1.0 h to obtain a black wet gel. Subsequently, the wet gel obtained above was subjected to aging treatment, and deionized water was used for solvent replacement 4 times with an interval of 10 h; the replaced wet gel was frozen in liquid nitrogen for 25 min, and then the frozen wet gel was subjected to freeze-drying treatment, with a drying temperature of -60 °C and a drying time of 36 h, to finally obtain Mn-anchored P-doped RuO2 fiber aerogel. The density of the prepared Mn-B / RuO2 fiber aerogel was 0.08 g / cm 3 , and the BET specific surface area was 65 m 2 / g. Electrochemical tests (e.g., cyclic voltammetry) showed that the overpotential of the catalyst was 223 mV (OER) and 33 mV (HER) in alkaline seawater (e.g., 1 M KOH) (e.g., a Figure 3 ). Figure 3 a、 Figure 3 b). The corrosion potential of the material was 1.21 V, and it had excellent anti-Cl - corrosion performance. When the Mn-B / RuO2 fiber aerogel was used as the catalyst for the cathode and the anode of an electrolytic water tank with an anion exchange membrane, the current density of the electrolytic tank reached 1.2 A / cm 2 (e.g., a Figure 3 e) at a voltage of 2 V, and the highest battery efficiency reached 78.8 %, realizing efficient and long-life electrolytic seawater hydrogen production. Example 5

[0032] A homogeneous spinning solution was obtained by dissolving 0.20 g of polyvinyl butyral, 0.18 g of ruthenocene and 0.02 g of melamine in 3 g of chloroform and stirring at 35 °C at 700 r / min for 16 h. The spinning solution was loaded into a syringe, and a flexible precursor nanofiber membrane was prepared by electrospinning technology, with the distance between the needle tip and the aluminum foil collector set to 30 cm, the push rate and the electric field voltage set to 0.80 mL / h and 20.0 kV, respectively. Then the nanofiber membrane was placed in a muffle furnace for calcination at 700 °C, with a heating rate of 6 °C / min and a holding time of 2.0 h, to obtain N-doped RuO2nanofibers. 40 mg of nanofibers were ultrasonically dispersed in deionized water (mass ratio 18:450). Subsequently, 8 mmol of sodium chromate, 16 mmol of ammonium molybdate tetrahydrate and 0.0075 mmol of sodium tartrate were dissolved in the solution containing the nanofibers, and stirred at 40 °C at 700 r / min for 60 min to mix uniformly, and then 60 mmol of sodium borohydride was slowly added and stirred at 700 r / min for 20 min to prepare a gel precursor solution. The co-precursor solution was placed at 55 °C for 4.0 h to obtain a black wet gel. Subsequently, the wet gel obtained above was subjected to aging treatment, and deionized water was used for solvent replacement 9 times with an interval of 3 h; the replaced wet gel was frozen in liquid nitrogen for 30 min, and then the frozen wet gel was subjected to freeze-drying treatment, with a drying temperature of -30 °C and a drying time of 40 h, to finally obtain CrMo-N-doped RuO2fibrous aerogel. The prepared CrMo-N / RuO2fibrous aerogel was subjected to electrochemical test (CV, LSV, Tafel, EIS) Figure 3 ), and it was found that in alkaline seawater, the overpotential of the catalyst was 228 mV (OER) and 35 mV (HER) Figure 3 a、 Figure 3 b), the corrosion potential of the material was 1.25 V, and the material had excellent anti-Cl - corrosion performance. When the CrMo-N / RuO2fibrous aerogel was used as the catalyst of the cathode and the anode of the anion exchange membrane electrolysis water tank, the current density of the electrolysis tank reached 1.25 A / cm 2 ( Figure 3 e) at a voltage of 2 V, realizing efficient and long-life electrolysis of seawater to produce hydrogen. Example 6

[0033] 0.25 g of polyvinylpyrrolidone, 0.25 g of ruthenium chloride trihydrate, and 0.025 g of diammonium hydrogen phosphate were dissolved in 4.67 g of dimethylformamide and stirred at 650 r / min for 15 h at 40 °C to obtain a homogeneous spinning solution. The spinning solution was loaded into a syringe, and a flexible precursor nanofiber membrane was prepared by electrospinning with the distance between the needle tip and the aluminum foil collector set to 26 cm, the feed rate set to 0.70 mL / h, and the electric field voltage set to 19.5 kV. The nanofiber membrane was then calcined in a muffle furnace at 650 °C with a heating rate of 5 °C / min and a holding time of 3.0 h to obtain P-doped RuO2 nanofibers. 40 mg of the nanofibers were ultrasonically dispersed in deionized water (mass ratio 20:500). Subsequently, 5 mmol of cobalt acetate tetrahydrate, 5 mmol of chromium nitrate nonahydrate, and 0.003 mmol of ethylenediaminetetraacetic acid were dissolved in a solution containing nanofibers. The mixture was stirred at 650 r / min for 30 min at 40 °C until homogeneous. Then, 35 mmol of citric acid was slowly added and stirred at 650 r / min for 20 min to prepare a gel precursor solution. The precursor solution was allowed to stand at 40 °C for 6.0 h to obtain a black wet gel. The wet gel was then subjected to aging treatment, during which solvent replacement with deionized water was performed 9 times, with each replacement occurring at 3-h intervals. The replaced wet gel was then frozen in liquid nitrogen for 25 min, followed by freeze-drying at -20 °C for 48 h to finally obtain CoCr-anchored P-doped RuO2 fiber aerogel. The prepared CoCr-P / RuO2 fiber aerogel was tested electrochemically (…). Figure 3 In alkaline seawater, the corrosion potential of this material is 1.23V. Figure 3 c), possesses excellent resistance to Cl. - Corrosion performance. When CoCr-P / RuO2 fiber aerogel is used as the catalyst for both the cathode and anode of an anion exchange membrane water electrolyzer, the current density reaches 1.35 A / cm² at 2 V. 2 ( Figure 3 c), and its performance showed no significant degradation after stable operation at 80 ℃ for 400 h. Figure 3 f) This enables efficient and long-life seawater electrolysis for hydrogen production. Electrochemical in-situ Raman spectroscopy revealed that as the voltage increases, Cr oxidizes to form Cr₂O₃, which acts as a Lewis acid layer, leading to a localized increase in the alkalinity of the catalyst surface and preferential enrichment of OH⁻. - Additionally, wavenumbers greater than 1000 cm⁻¹ -1 The peaks correspond to characteristic peaks related to phosphate, which form a dynamic protective layer through charge repulsion, thereby achieving a synergistic protection mechanism to effectively resist Cl. - corrosion( Figure 3g)。 Example 7

[0034] A homogeneous spinning solution was prepared by dissolving 0.2 g of polyacrylonitrile, 0.4 g of ruthenium acetate and 0.04 g of phytic acid in 6 g of hexafluoroisopropanol, and stirring at 35 °C at 800 r / min for 16 h. The spinning solution was loaded into a syringe, and a flexible precursor nanofiber membrane was prepared by electrospinning technology, with the distance between the needle tip and the aluminum foil collector set to 22 cm, the push rate and the electric field voltage set to 0.65 mL / h and 18.5 kV, respectively. Then the nanofiber membrane was placed in a muffle furnace for calcination at 550 °C, with a heating rate of 4 °C / min and a holding time of 3.0 h, to obtain P-doped RuO2nanofibers. 45 mg of the nanofibers were ultrasonically dispersed in deionized water (mass ratio of 13:350). Subsequently, 21 mmol of chromium nitrate nonahydrate, 5.5 mmol of iron chloride hexahydrate and 0.003 mmol of lysine were dissolved in the solution containing the nanofibers, and stirred at 30 °C at 900 r / min for 50 min to mix uniformly, and then 48 mmol of citric acid was slowly added and stirred at 900 r / min for 20 min to prepare a gel precursor solution. The co-precursor solution was left to stand at 25 °C for 3.5 h to obtain a black wet gel. Subsequently, the wet gel obtained above was subjected to aging treatment, and deionized water was used for solvent replacement for 6 times, with an interval of 4 h each time; the replaced wet gel was frozen in liquid nitrogen for 20 min, and then the frozen wet gel was subjected to freeze-drying treatment, with a drying temperature of -42 °C and a drying time of 48 h, to finally obtain CrFe-anchored P-doped RuO2fiber aerogel. The CrFe-P / RuO2fiber aerogel was used as the catalyst for the cathode and the anode of an electrolytic cell for electrolysis of seawater, and the current density reached 1.2 A / cm 2 Figure 3 Figure 3 Figure 3 Figure 3 Figure 3 Figure 3 Figure 3 Figure 3 Figure 3 Figure 3 Figure 3 Figure 3 Figure 3 Figure 3 Figure 3 Figure 3 Figure 3 e) at a voltage of 1.8 V, and the highest battery efficiency reached 78.6 %, realizing efficient and long-life electrolysis of seawater to produce hydrogen. ​This invention employs electrospinning combined with metal self-assembly and freeze-drying techniques to design a method for preparing a fiber aerogel electrocatalyst based on Lewis acid-anion charge repulsion synergistic protection for electrocatalysis, achieving high-efficiency OER / HER catalytic performance and overcoming the bottleneck of poor stability in seawater electrolysis hydrogen production catalysts. The method involves preparing RuO2 fibers as a catalytic substrate with high intrinsic activity and high conductivity via electrospinning, then anchoring transition metal nanoparticles onto the RuO2 fibers using metal self-assembly technology to form a continuous conductive network. Finally, one-dimensional fibers are reconstructed into a three-dimensional hierarchical porous aerogel structure through ice crystal directional growth combined with freeze-drying. This provides an efficient channel for electrolyte mass transfer and gaseous product escape, and achieves uniform distribution and full exposure of active sites. During the OER process, the transition metal nanoparticles are converted in situ to M-OH, subsequently undergoing deprotonation to form a Lewis acid layer. This synergistically regulates the electronic structure with RuO2, effectively inhibiting Ru... n+ Excessive oxidation, and simultaneously affecting Cl - This generates strong electrostatic repulsion. To further address the issue of susceptibility to erosion of active species in traditional catalysts, the doped heteroatoms can be oxidized in an alkaline environment to form negatively charged anionic groups, effectively resisting Cl through charge repulsion. - Corrosion. By establishing a Lewis acid-anion charge repulsion dual anti-corrosion mechanism, the bottleneck of poor catalyst stability in high-salinity seawater environments can be overcome. This invention addresses three major pain points in seawater electrolysis for hydrogen production (insufficient catalyst activity, Cl...). - (Severe corrosion and low mass transfer efficiency) are addressed by enhancing bifunctional activity through multi-component coupling (RuO2 / M-OH synergistic catalysis), improving mass transfer and electron conduction through a three-dimensional porous structure, and utilizing a Lewis acid-bound anion layer to resist Cl. - Erosion significantly enhances catalytic activity and stability, which is of great significance for the large-scale industrialization of hydrogen production from renewable energy.

[0035] This invention provides a transition metal-anchored heteroatom-doped RuO2 fiber aerogel electrocatalyst, its preparation method, and its application. Many methods and approaches exist for implementing this technical solution; the above description is merely a preferred embodiment. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications should also be considered within the scope of protection of this invention. All components not explicitly stated in this embodiment can be implemented using existing technologies.

Claims

1. A method for the preparation of transition metal anchor heteroatom doped Ru02fibrous aerogel electrocatalyst, characterized in that, The method comprises the following steps: S1, dissolving the polymer, ruthenium salt and non-metallic compound in a polar solvent, and stirring uniformly to obtain a spinning solution; S2, preparing a flexible precursor nanofiber membrane by electrospinning the spinning solution obtained in step S1; S3, calcining the flexible precursor nanofiber membrane obtained in step S2 to obtain a heteroatom-doped RuO2 nanofiber; S4, ultrasonic dispersing the heteroatom-doped RuO2 nanofiber prepared in step S3 in deionized water to obtain a dispersion solution containing nanofibers, then dissolving a transition metal salt and an organic ligand in the solution, stirring uniformly at room temperature, slowly adding a reducing agent and stirring to prepare a gel precursor solution; S5, placing the gel precursor solution prepared in step S4 at 25-55 °C for 1.0-6.0 h to obtain a wet gel; S6, aging the wet gel obtained in step S5, washing multiple times with deionized water during the aging process, and finally performing freeze-drying treatment.

2. The method of making a transition metal anchor heteroatom-doped Ru02fibrous aerogel electrocatalyst of claim 1, wherein, In step S1, the polymer is selected from any one of polyvinylpyrrolidone, polyacrylonitrile, polyamide, polyvinyl alcohol and polyvinyl butyral; The ruthenium salt is selected from any one of ruthenium chloride trihydrate, potassium hexachlororuthenate, ruthenium acetate, trispyridine ruthenium chloride hexahydrate and ruthenocene; The non-metallic compound is selected from any one of a nitrogen-containing compound, a phosphorus-containing compound, a sulfur-containing compound and a boron-containing compound; the nitrogen-containing compound is any one of ethylenediamine, urea, melamine, hydrazine hydrate and propionitrile; the phosphorus-containing compound is any one of phytic acid, phosphoric acid, diammonium hydrogen phosphate, sodium hypophosphite and triphenylphosphine; the sulfur-containing compound is any one of thiophene, thiourea, sulfuric acid, thioacetamide and mercaptan; and the boron-containing compound is any one of boric acid, diboron trioxide, trimethyl borate, sodium tetraphenylborate and boron trichloride; The polar solvent is selected from any one of dimethylformamide, ethanol, acetone, chloroform, formic acid and hexafluoroisopropanol or a mixture of two or more thereof.

3. The method of making a transition metal anchor heteroatom-doped Ru02fibrous aerogel electrocatalyst of claim 1, wherein, In step S1, the mass ratio of the polymer, ruthenium salt, non-metallic compound and polar solvent is (5-20):(5-20):(1-2):(50-300); the stirring temperature is controlled at 20-40 °C, and the stirring time is 8-16 h.

4. The method of making a transition metal anchor heteroatom-doped Ru02fibrous aerogel electrocatalyst of claim 1, wherein, In step S2, the spinning solution is loaded into a syringe, and the distance between the needle tip of the syringe and the aluminum foil collector is 10-30 cm during electrospinning, and the push rate and electric field voltage are set to 0.10-0.80 mL / h and 14-20 kV, respectively.

5. The method of making a transition metal anchor heteroatom-doped Ru02fibrous aerogel electrocatalyst of claim 1, wherein, In step S3, the calcination temperature is 400-700 °C, the heating rate is 2-6 °C / min, and the holding time is 2-7 h.

6. The method of making a transition metal anchor heteroatom-doped Ru02fibrous aerogel electrocatalyst of claim 1, wherein, In step S4, the mass ratio of the heteroatom-doped RuO2 nanofiber to deionized water is (1-20):(200-500); the transition metal salt, organic ligand and reducing agent are mixed in a molar concentration of (2-25 mmol / L):(0.0002-0.0075 mmol / L):(2-50 mmol / L), respectively.

7. The method of making a transition metal anchor heteroatom-doped Ru02fibrous aerogel electrocatalyst of claim 1, wherein, The transition metal salt in step S4 is selected from any one of copper salt, nickel salt, cobalt salt, manganese salt, iron salt, chromium salt, molybdenum salt; The copper salt is one of copper chloride trihydrate, copper nitrate pentahydrate, copper sulfate pentahydrate, copper carbonate; The nickel salt is one of nickel chloride hexahydrate, nickel nitrate hexahydrate, nickel sulfate hexahydrate, nickel nitrite; The cobalt salt is one of cobalt chloride hexahydrate, cobalt acetate tetrahydrate, cobalt sulfate heptahydrate, cobalt nitrate hexahydrate; The manganese salt is one of manganese chloride tetrahydrate, manganese sulfate monohydrate, manganese nitrate tetrahydrate, manganese carbonate; The iron salt is one of iron chloride hexahydrate, iron nitrate nonahydrate, iron sulfate nonahydrate, ferrous sulfate heptahydrate, iron carbonate; The chromium salt is one of chromium chloride hexahydrate, chromium nitrate nonahydrate, sodium chromate, ammonium chromate, sodium dichromate; The molybdenum salt is one of sodium molybdate dihydrate, ammonium molybdate tetrahydrate, sodium hydrogen molybdate, ammonium chromate, sodium dichromate.

8. The method of making a transition metal anchor heteroatom-doped Ru02fibrous aerogel electrocatalyst of claim 1, wherein, The organic ligand in step S4 is any one of sodium citrate, sodium tartrate, cysteine, lysine, mercaptoalkanoic acid and ethylenediaminetetraacetic acid; and the reducing agent is any one of sodium borohydride, potassium borohydride, ascorbic acid, glucose, citric acid.

9. The transition metal-anchored heteroatom-doped RuO2 fiber aerogel electrocatalyst prepared by the preparation method in any one of claims 1-8.

10. The application of the transition metal-anchored heteroatom-doped RuO2 fiber aerogel electrocatalyst in claim 9 in electrolysis of seawater for hydrogen production.

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