A manganese oxide-based core-shell structure catalyst, a preparation method and application thereof, and a working electrode and a preparation method and application thereof

Abstract

The present application relates to the technical field of hydrogen production by water electrolysis, and particularly relates to a manganese oxide-based core-shell structure catalyst, a preparation method and application thereof, and a working electrode and a preparation method and application thereof. The present application takes boron-doped manganese dioxide as a carrier and loads noble metal. By doping boron in the manganese dioxide, the present application can effectively adjust the electronic structure of the manganese dioxide, significantly improve the electronic conductivity of the manganese dioxide carrier, and further improve the charge transmission in the OER process. Moreover, the boron atom has strong affinity to the surface metal atom due to its electron-deficient characteristics, can form a metal-B-O combination site, thereby strengthening the anchoring capacity of the noble metal active component, further constructing a stable interface of the noble metal-base, and significantly reducing the amount of the noble metal. The manganese oxide-based core-shell structure catalyst provided by the present application has good intrinsic conductivity, high electrocatalytic activity and excellent structural durability, and provides a feasible material solution for realizing the low-cost and long-life PEM electrolysis technology.

Description

Technical Field

[0001] This invention relates to the field of water electrolysis for hydrogen production, specifically to a manganese oxide-based core-shell catalyst, its preparation method and application, and a working electrode, its preparation method and application. Background Technology

[0002] Hydrogen energy, as a crucial clean energy carrier for achieving carbon neutrality, has attracted significant attention for its green production pathways. Among these, proton exchange membrane (PEM) water electrolysis technology, with its high current density, high hydrogen purity, and millisecond-level dynamic response, is considered a core solution for efficient hydrogen production coupled with fluctuating renewable energy sources such as wind and solar power. However, the slow kinetics of the oxygen evolution reaction at the anolyte in this technology lead to high overpotentials, and its efficient catalysis heavily relies on the extremely scarce precious metal iridium, resulting in high catalyst costs. Although attempts have been made to reduce iridium usage through strategies such as preparing low-dimensional catalysts or alloying, it remains difficult to simultaneously maintain the intrinsic activity and long-term durability of the material under strongly acidic, high-potential anolyte conditions. Therefore, developing novel electrode materials that simultaneously possess high catalytic activity and excellent structural stability under low-iridium conditions and harsh anolyte environments has become a key challenge driving the development of PEM water electrolysis technology.

[0003] Supported catalyst systems, through the synergistic effect between the active component and the support, can effectively overcome the bottlenecks in activity and stability of single materials. Among them, manganese dioxide (MnO2) has become a highly promising support material due to its rich crystalline structures and tunable electronic properties. In particular, β-MnO2, with its 1×1 tunnel structure formed by octahedral edge connections, exhibits excellent structural stability thermodynamically and can effectively resist H+ in acidic environments. + The catalytic activity of β-MnO2 significantly delays phase transitions or dissolution due to erosion and the loss of lattice oxygen caused by high potential during the oxygen evolution reaction (OER). However, the poor intrinsic conductivity of β-MnO2 limits further improvement in its catalytic performance. Summary of the Invention

[0004] Therefore, the purpose of this invention is to provide a manganese oxide-based core-shell structured catalyst, its preparation method and application, and a working electrode, its preparation method and application. The manganese oxide-based core-shell structured catalyst provided by this invention exhibits good intrinsic conductivity, high electrocatalytic activity, and excellent structural durability.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a manganese oxide-based core-shell structured catalyst, with boron-doped manganese dioxide as the core and a noble metal as the shell.

[0006] Preferably, the precious metal includes at least one of iridium and ruthenium; The manganese oxide-based core-shell catalyst contains 1-10% noble metals by mass.

[0007] This invention also provides a method for preparing the manganese oxide-based core-shell structured catalyst described in the above technical solution, comprising the following steps: Manganese dioxide, boric acid, and ethanol are mixed and a doping reaction is carried out to obtain boron-doped manganese dioxide. The boron-doped manganese dioxide, the noble metal precursor, and water are mixed and subjected to a hydrothermal reaction to obtain the manganese oxide-based core-shell catalyst.

[0008] Preferably, the manganese dioxide is nano-manganese dioxide; the microstructure of the nano-manganese dioxide includes at least one of nanoparticles, nanowires, nanotubes, nanodendritic crystals, nanoflowers, nanorods and nanostars. The molar ratio of manganese dioxide to boric acid is 0.01~100:1; The doping reaction is carried out at a temperature of 30~90℃ for a time of 0.1~48h.

[0009] Preferably, the noble metal precursor includes at least one of an iridium precursor and a ruthenium precursor; the iridium precursor includes at least one of iridium trichloride, iridium tetrachloride, and chloroiridium acid; the ruthenium precursor includes at least one of ruthenium trichloride, ruthenium acetylacetonate, potassium ruthenate, ammonium ruthenate, and ruthenium acetate. The molar ratio of manganese in the boron-doped manganese dioxide to the noble metal in the noble metal precursor is 0.01~100:1; The hydrothermal reaction is carried out at a temperature of 100~300℃ for a time of 1~36h.

[0010] The present invention also provides a working electrode, comprising a glassy carbon electrode and an active material layer located on the surface of the glassy carbon electrode, wherein the active material layer comprises a catalyst, conductive carbon powder and Nafion; wherein the catalyst is a manganese oxide-based core-shell structure catalyst as described in the above technical solution or a manganese oxide-based core-shell structure catalyst prepared by the preparation method described in the above technical solution.

[0011] Preferably, the mass ratio of the catalyst to the conductive carbon powder is 0.2 to 5:1.

[0012] The present invention also provides a method for preparing the working electrode described in the above technical solution, comprising the following steps: The ink is obtained by mixing the catalyst, conductive carbon powder, isopropanol, water, and Nafion solution. The ink is coated onto the upper surface of a glassy carbon electrode to obtain a working electrode.

[0013] Preferably, the concentration of the catalyst in the ink is 1~5 g / L; The ink contains 10-80% isopropanol by volume and 1-10% Nafion solution by volume.

[0014] This invention also provides the application of the manganese oxide-based core-shell structure catalyst described in the above technical solution, the manganese oxide-based core-shell structure catalyst prepared by the preparation method described in the above technical solution, the working electrode described in the above technical solution, or the working electrode prepared by the preparation method described in the above technical solution in the field of water electrolysis for hydrogen production.

[0015] This invention provides a manganese oxide-based core-shell catalyst with boron-doped manganese dioxide as the core and a noble metal as the shell. By doping manganese dioxide with the non-metallic element boron (B), this invention effectively modulates the electronic structure of manganese dioxide, significantly improving the electronic conductivity of the manganese dioxide support and thus enhancing charge transport during the OER process. Furthermore, the electron-deficient nature of B atoms gives them a strong affinity for surface metal atoms, forming metal-BO binding sites, thereby strengthening the anchoring ability of the noble metal active component, further constructing a stable noble metal-substrate interface, and significantly reducing the amount of noble metal required. The manganese oxide-based core-shell catalyst provided by this invention exhibits good intrinsic conductivity, high electrocatalytic activity, and excellent structural durability, providing a feasible material solution for achieving low-cost, long-life PEM electrolysis technology.

[0016] The manganese oxide-based core-shell structured catalyst provided by this invention successfully solves the core contradiction of activity and stability in proton exchange membrane (PEM) water electrolysis for hydrogen production anode catalysts. While significantly improving catalytic performance and structural durability, it successfully reduces the amount of precious metal iridium used, providing a feasible material solution for achieving low-cost, long-life PEM electrolysis technology.

[0017] This invention uses MnO2 as a substrate and employs boron doping via a hydrothermal reaction to load noble metals. This ensures the effective introduction of boron atoms and the effective loading of noble metal elements, enhancing the electron transport and catalytic activity of the manganese oxide-based core-shell catalyst and mitigating metal dissolution and catalyst deactivation issues. The preparation method provided by this invention significantly improves electrocatalytic performance and structural durability while successfully reducing the amount of noble metal used to a low level, offering a feasible material solution for achieving low-cost, long-life PEM electrolysis technology. Furthermore, the preparation method provided by this invention is simple to operate, environmentally friendly, non-toxic, and has low production costs. Attached Figure Description

[0018] Figure 1 SEM and EDS images of the manganese oxide-based core-shell catalyst prepared in Example 3; Figure 2XRD patterns of B-MnO2 prepared in Example 1, manganese oxide-based core-shell catalysts prepared in Examples 1-3 and Comparative Example 1; Figure 3 Linear sweep voltammetry (LSV) results of manganese oxide-based core-shell catalysts prepared in Examples 1-3 and Comparative Examples 1-3; Figure 4 Linear sweep voltammetry (LSV) results of the manganese oxide-based core-shell catalysts prepared in Examples 3 and 12-14; Figure 5 Linear sweep voltammetry (LSV) curves of manganese oxide-based core-shell catalyst, commercial iridium oxide, and commercial ruthenium oxide prepared in Example 3 during water electrolysis oxygen production tests; Figure 6 The performance curve of the manganese oxide-based core-shell catalyst prepared in Example 3 is shown in the PEM water electrolysis test. Detailed Implementation

[0019] This invention provides a manganese oxide-based core-shell structured catalyst, with boron-doped manganese dioxide as the core and a noble metal as the shell.

[0020] In this invention, the noble metal may include at least one of iridium and ruthenium. In this invention, the mass percentage of the noble metal in the manganese oxide-based core-shell catalyst may be 1-10%, specifically 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10%.

[0021] In this invention, the molar content of boron in the boron-doped manganese dioxide can be 0.1% to 10%, or 1% to 8%, specifically 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10%. This invention improves the conductivity of MnO2 through boron doping, thereby enhancing the oxygen evolution performance of the manganese oxide-based core-shell catalyst.

[0022] This invention also provides a method for preparing the manganese oxide-based core-shell structured catalyst described in the above technical solution, comprising the following steps: Manganese dioxide, boric acid, and ethanol are mixed and a doping reaction is carried out to obtain boron-doped manganese dioxide. The boron-doped manganese dioxide, the noble metal precursor, and water are mixed and subjected to a hydrothermal reaction to obtain the manganese oxide-based core-shell catalyst.

[0023] Unless otherwise specified, the materials and equipment used in this invention are all commercially available products in the field.

[0024] This invention involves mixing manganese dioxide, boric acid, and ethanol to perform a doping reaction, thereby obtaining boron-doped manganese dioxide.

[0025] In this invention, the manganese dioxide can be nano-manganese dioxide; the microstructure of the nano-manganese dioxide can include at least one of nanoparticles, nanowires, nanotubes, nanodendritic crystals, nanoflowers, nanorods and nanostars, and can specifically be nanotubes; when the microstructure of the nano-manganese dioxide is at least two of the above microstructures, this invention does not have any special limitation on the ratio of nano-manganese dioxide with different microstructures, and they can be mixed in any ratio.

[0026] In this invention, the molar ratio of manganese dioxide to boric acid can be 0.01 to 100:1, or 0.5 to 10:1, or even 1 to 5:1, specifically 1.15:1, 1.5:1 or 2:1.

[0027] In this invention, the mixing can be achieved by dispersing boric acid in ethanol to obtain an ethanol solution of boric acid; and then mixing the manganese dioxide with the ethanol solution of boric acid. In this invention, the concentration of the ethanol solution of boric acid can be 0.1~1 mol / L, or 0.2~0.8 mol / L, or further 0.4~0.6 mol / L, specifically 0.5 mol / L. This invention does not have a particular limitation on the dispersion method, as long as it can uniformly disperse boric acid in ethanol.

[0028] In this invention, the temperature of the doping reaction can be 30~90℃, or 40~80℃, specifically 50℃, 60℃, 70℃, 80℃ or 90℃; the time of the doping reaction can be 0.1~48h, or 3~40h, or even 5~30h, specifically 6h, 8h, 10h, 12h, 15h, 20h, 25h, 30h or 35h.

[0029] After the doping reaction is completed, the present invention may further include: sequentially centrifuging and washing the system after the doping reaction and drying it to obtain boron-doped manganese dioxide. The present invention does not impose any special limitations on the centrifugal washing; any centrifugal washing process well known to those skilled in the art can be used. In the present invention, the centrifugal washing may be performed using ethanol, and the number of centrifugal washing cycles may be 3-12 times, or 5-10 times, specifically 6 times. In the present invention, the drying method may be freeze-drying. The present invention does not impose any special limitations on the freeze-drying conditions; any freeze-drying conditions well known to those skilled in the art can be used. In an embodiment of the present invention, the freeze-drying time may be 24 hours.

[0030] After obtaining boron-doped manganese dioxide, the present invention mixes the boron-doped manganese dioxide, a noble metal precursor, and water, and carries out a hydrothermal reaction to obtain the manganese oxide-based core-shell structure catalyst.

[0031] In this invention, the noble metal precursor may include at least one of iridium precursor and ruthenium precursor; the iridium precursor may include at least one of iridium trichloride, iridium tetrachloride and chloroiridium acid; the ruthenium precursor may include at least one of ruthenium trichloride, ruthenium acetylacetonate, potassium ruthenate, ammonium ruthenate and ruthenium acetate.

[0032] In this invention, the molar ratio of manganese in boron-doped manganese dioxide to noble metal in the noble metal precursor can be 0.01~100:1, or 5~80:1, or even 10~50:1, or specifically 15:1, 20:1, 23:1, 25:1, 30:1, 40:1 or 50:1.

[0033] In this invention, the mixing can be as follows: dispersing boron-doped manganese dioxide in a portion of water to obtain a boron-doped manganese dioxide aqueous dispersion; dispersing a noble metal precursor in water to obtain a noble metal precursor aqueous dispersion; and mixing the boron-doped manganese dioxide aqueous dispersion and the noble metal precursor aqueous dispersion. In this invention, the concentration of the boron-doped manganese dioxide aqueous dispersion can be 0.05~0.5 mol / L, or 0.1~0.4 mol / L, or further 0.2~0.3 mol / L. In this invention, the concentration of the noble metal precursor aqueous dispersion can be 0.01~0.1 mol / L, or 0.03~0.06 mol / L, or further 0.04~0.05 mol / L.

[0034] In this invention, the temperature of the hydrothermal reaction can be 100~300℃, or 140~250℃, specifically 120℃, 140℃, 160℃, 180℃, 200℃, 250℃ or 300℃; the time of the hydrothermal reaction can be 1~36h, or 5~30h, specifically 1h, 4h, 6h, 8h, 10h, 15h, 20h, 24h, 30h or 36h.

[0035] After completing the hydrothermal reaction, the present invention may further include: sequentially centrifuging and washing the system after the hydrothermal reaction and drying it to obtain a manganese oxide-based core-shell catalyst. The present invention does not impose any special limitations on the centrifugal washing; any centrifugal washing process well-known to those skilled in the art can be used. In the present invention, the centrifugal washing may be performed using ethanol, and the number of centrifugal washing cycles may be 3-12 times, or 5-10 times, specifically 6 times. In the present invention, the drying method may be freeze-drying. The present invention does not impose any special limitations on the freeze-drying conditions; any freeze-drying conditions well-known to those skilled in the art can be used; in the embodiments of the present invention, the freeze-drying time may be 24 hours.

[0036] This invention also provides the application of the manganese oxide-based core-shell structure catalyst described in the above technical solution or the manganese oxide-based core-shell structure catalyst prepared by the above technical solution in the field of hydrogen production by water electrolysis.

[0037] The present invention also provides a working electrode, the working electrode comprising a glassy carbon electrode and an active material layer located on the surface of the glassy carbon electrode; the active material layer comprises a catalyst, conductive carbon powder and Nafion; the catalyst is a manganese oxide-based core-shell structure catalyst as described in the above technical solution or a manganese oxide-based core-shell structure catalyst prepared by the preparation method described in the above technical solution.

[0038] In this invention, the mass ratio of the catalyst to the conductive carbon powder can be 0.2~5:1, or 0.5~3:1, or even 1~2:1, or specifically 1:1.

[0039] The present invention also provides a method for preparing the working electrode described in the above technical solution, comprising the following steps: mixing a catalyst, conductive carbon powder, isopropanol, water and Nafion solution to obtain an ink; coating the ink onto the upper surface of a glassy carbon electrode to obtain a working electrode.

[0040] In this invention, the concentration of the catalyst in the ink can be 1-5 g / L, or 2-4 g / L, or even 2-3 g / L. In this invention, the volume fraction of isopropanol in the ink can be 10-80%, or 40-70%, or even 50-60%; the volume fraction of Nafion solution in the ink can be 1-10%, or 5-10%, or even 8-10%. In this invention, the volume ratio of isopropanol, water, and Nafion solution can specifically be 6:3:1. In this invention, the concentration of the Nafion solution can be 5 wt%.

[0041] In this invention, the coating method may include drop-addition, and the ratio of the coating amount of ink to the diameter of the glassy carbon electrode may be 8~15μL:3mm, or 9~10μL:3mm.

[0042] This invention also provides the application of the manganese oxide-based core-shell structure catalyst described in the above-described technical solutions, the manganese oxide-based core-shell structure catalyst prepared by the preparation method described in the above-described technical solutions, the working electrode described in the above-described technical solutions, or the working electrode prepared by the preparation method described in the above-described technical solutions, in the field of hydrogen production through water electrolysis. In this invention, the hydrogen production through water electrolysis can be carried out in a sulfuric acid solution; the concentration of the sulfuric acid solution can be 0.1~1 mol / L, or 0.2~0.8 mol / L, or further 0.4~0.6 mol / L, specifically 0.5 mol / L; the sulfuric acid solution can be an O2-saturated sulfuric acid solution.

[0043] This invention effectively modulates the electronic structure of manganese dioxide by doping it with the non-metallic element boron (B), significantly improving the electronic conductivity of the manganese dioxide carrier and thus enhancing charge transport during the OER process. Furthermore, the electron-deficient nature of boron atoms gives them a strong affinity for surface metal atoms, forming metal-BO binding sites. This strengthens the anchoring ability of the noble metal active components, further constructing a stable noble metal-substrate interface. It also significantly reduces the amount of noble metal used, providing a feasible material solution for achieving low-cost, long-life PEM electrolysis technology.

[0044] Compared with the PEM ternary alloy catalyst for hydrogen production by water electrolysis prepared in CN120967404A, the raw materials used in the preparation of the manganese oxide-based core-shell structure catalyst of this invention are simpler and safer, and the synthesis steps are simpler, making it very suitable for large-scale production. The amount of precious metals used in this invention is significantly reduced. According to ICP test data, the mass ratio of precious metals is only about 4% (Example 3), which shows extremely high mass activity. Moreover, the actual PEM test data of the manganese oxide-based core-shell structure catalyst provided by this invention are excellent, and it does not stop at the three-electrode test stage.

[0045] To further illustrate the present invention, the technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0046] Example 1 Nanorods containing MnO2 were added to an ethanol solution of boric acid with a concentration of 0.05 mol / L and the doping reaction was carried out at 80 °C for 6 h. The nanorods were washed 6 times by centrifugation with ethanol and then freeze-dried for 24 h to obtain B-MnO2. The mass ratio of Mn to B was 15:4.

[0047] B-MnO2 was dispersed in deionized water, and a 0.05 mol / L ruthenium trichloride aqueous dispersion was added. The mixture was hydrothermally reacted at 165 °C for 12 h, followed by washing six times with ethanol by centrifugation and freeze-drying for 24 h to obtain B-MnO2@Ru. The ratio of B-MnO2, deionized water, and ruthenium trichloride was 10 mg: 30 mL: 5 μmmol.

[0048] Example 2 B-MnO2@Ir was prepared according to the method of Example 1, the only difference from Example 1 being that ruthenium trichloride was replaced with chloroiridic acid.

[0049] Example 3 B-MnO2 was prepared according to Example 1.

[0050] B-MnO2 was dispersed in deionized water, and then a 0.05 mol / L aqueous dispersion of chloroiridic acid and a 0.05 mol / L aqueous dispersion of ruthenium trichloride were added. The mixture was hydrothermally reacted at 165 °C for 12 h, followed by washing six times with ethanol by centrifugation and freeze-drying for 24 h to obtain B-MnO2@Ir1Ru1. The ratio of B-MnO2, deionized water for dispersion, chloroiridic acid, and ruthenium trichloride was 10 mg: 30 mL: 2.5 μmol: 2.5 μmol.

[0051] ICP test results show that the noble metal content in B-MnO2@Ir1Ru1 prepared in Example 3 is only about 4%, indicating extremely high mass activity.

[0052] Example 4 B-MnO2@Ir1Ru3 was prepared according to Example 1, the only difference from Example 3 being that the ratio of B-MnO2, chloroiridic acid and ruthenium trichloride was 10 mg: 30 mL: 1.25 μmol: 3.75 μmol.

[0053] Example 5 B-MnO2@Ir3Ru1 was prepared according to Example 1, the only difference from Example 3 being that the ratio of B-MnO2, chloroiridic acid and ruthenium trichloride was 10 mg: 30 mL: 3.75 μmol: 1.25 μmol.

[0054] Example 6 The only difference from Example 3 is that the hydrothermal reaction time is 6 hours.

[0055] Example 7 The only difference from Example 3 is that the hydrothermal reaction time is 24 hours.

[0056] Example 8 The only difference from Example 3 is that the hydrothermal reaction temperature is 140°C.

[0057] Example 9 The only difference from Example 3 is that the hydrothermal reaction temperature is 180°C.

[0058] Example 10 The only difference from Example 3 is that chloroiridic acid is replaced with iridium trichloride.

[0059] Example 11 The only difference from Example 3 is that chloroiridic acid is replaced with iridium tetrachloride.

[0060] Comparative Example 1 MnO2 was dispersed in deionized water, and a 0.05 mol / L ruthenium trichloride aqueous dispersion was added. The mixture was hydrothermally reacted at 165 °C for 12 h, followed by washing six times with ethanol by centrifugation and freeze-drying for 24 h to obtain MnO2@Ru. The ratio of MnO2, deionized water, and ruthenium trichloride was 10 mg: 30 mL: 5 μmol.

[0061] Comparative Example 2 MnO2 was dispersed in deionized water, and a 0.05 mol / L aqueous dispersion of chloroiridium acid was added. The mixture was subjected to a hydrothermal reaction at 165 °C for 12 h. After washing six times by centrifugation with ethanol, the mixture was freeze-dried for 24 h to obtain MnO2@Ir. The ratio of MnO2, deionized water for dispersion, and chloroiridium acid was 10 mg: 30 mL: 5 μmol.

[0062] Comparative Example 3 MnO2 was dispersed in deionized water, and then a 0.05 mol / L aqueous dispersion of chloroiridic acid and a 0.05 mol / L aqueous dispersion of ruthenium trichloride were added. The mixture was hydrothermally reacted at 165 °C for 12 h, followed by washing six times with ethanol by centrifugation and freeze-drying for 24 h to obtain MnO2@Ir1Ru1. The ratio of MnO2, deionized water for dispersion, chloroiridic acid, and ruthenium trichloride was 10 mg: 30 mL: 2.5 μmol: 2.5 μmol.

[0063] Example 12 The only difference from Example 3 is that the mass ratio of Mn to B is 15:1.

[0064] Example 13 The only difference from Example 3 is that the mass ratio of Mn to B is 15:2.

[0065] Example 14 The only difference from Example 3 is that the mass ratio of Mn to B is 15:8.

[0066] Figure 1 The SEM and EDS images of B-MnO2@Ir1Ru1 prepared in Example 3 show that the B-MnO2@Ir1Ru1 catalyst exhibits a clear nanorod structure and is uniformly loaded with noble metals iridium and ruthenium.

[0067] Figure 2 The XRD patterns of B-MnO2 prepared in Example 1, and the manganese oxide-based core-shell catalysts prepared in Examples 1-3 and Comparative Example 1 show that boron doping causes the diffraction peaks of manganese dioxide to shift to higher angles. This is due to the strong electron-withdrawing effect of boron, which promotes the partial removal of Mn from manganese dioxide. 3+ To Mn 4+The transformation, along with the formation of shorter BO bonds between boron and oxygen, shrinks the MnO6 coordination framework, collectively causing manganese dioxide cell shrinkage; after hydrothermal loading of noble metals, the diffraction peaks of manganese dioxide shift to lower angles, originating from interfacial electron transfer between the noble metal and the support, Mn 4+ Reduced to Mn 3+ The average radius of manganese rebounded, and at the same time, the insertion of noble metal particles into the lattice caused tensile lattice strain, which together promoted the expansion of the unit cell.

[0068] Table 1 shows the four-probe resistance test data for manganese dioxide and boron-doped manganese dioxide.

[0069] As shown in Table 1, the sheet resistance and resistivity of boron-doped manganese dioxide are both lower than those of manganese dioxide, indicating that the introduction of boron successfully enhances the conductivity of manganese dioxide.

[0070] Application Example 1 The oxygen production from water electrolysis was tested using the B-MnO2@Ir1Ru1 prepared in Example 3. A standard three-electrode system was used at room temperature on a CHI 660E workstation (CH Instruments, Shanghai Chenhua Co., Ltd.). The catalyst (manganese oxide-based core-shell catalysts prepared in Examples 1-3, manganese oxide-based core-shell catalysts prepared in Comparative Examples 1-3, and commercial iridium oxide or commercial ruthenium oxide) was mixed with conductive carbon powder at a 1:1 mass ratio. Isopropanol, water, and a 5wt% Nafion solution were added in a volume ratio of 6:3:1 to obtain ink (the catalyst concentration in the ink was 2 g / L). 10 μL of the ink was dropped onto a glassy carbon electrode (3 mm in diameter) and allowed to dry naturally to constant weight to obtain the working electrode. A graphite rod was used as the counter electrode, and a saturated calomel reference electrode was used as the reference electrode. The oxygen production from water electrolysis was tested in a 0.5 mol / L O2-saturated sulfuric acid solution, and the oxygen evolution reaction (OER) was studied at a scan rate of 50 mV / s. All electrode potentials are referenced relative to the reversible hydrogen electrode (RHE).

[0071] Overpotential (η) refers to the portion of the actual voltage exceeding the theoretical voltage required to achieve a certain current density in an electrocatalytic or photoelectrocatalytic reaction. The overpotential value obtained by LSV measurement is one of the key indicators for evaluating the performance of water electrolysis catalysts. Theoretically, for the oxygen evolution reaction, the closer the overpotential is to 1.23V, the better the catalyst's performance. To facilitate comparison of the electrocatalytic activity of different materials, an overpotential of 10 mA / cm² is used. 2 At the current density, the reversible hydrogen potential (RHE) is converted for comparison.

[0072] Figure 3The linear sweep voltammetry (LSV) results of the manganese oxide-based core-shell catalysts prepared in Examples 1-3 and Comparative Examples 1-3 show that all the manganese oxide-based core-shell catalysts prepared in Examples 1-3 exhibit excellent OER activity, with Example 3 showing the best activity. Furthermore, compared to their respective undoped Comparative Examples 1-3, the boron-doped Examples 1-3 all showed improved performance.

[0073] Figure 4 The linear sweep voltammetry (LSV) results for the manganese oxide-based core-shell catalysts prepared in Examples 3 and 12-14 show that the manganese oxide-based core-shell catalysts prepared in Examples 3 and 12-14 exhibit linear sweep voltammetry (LSV) at 10 mA / cm². 2 The overpotentials were 230mV, 239mV, 235mV, and 253mV, respectively, all of which showed excellent OER activity. Among them, Example 3 showed the best activity. Excess boron would affect the adsorption effect of iridium and ultimately affect the performance.

[0074] Figure 5 The linear sweep voltammetry (LSV) curves of the manganese oxide-based core-shell catalyst prepared in Example 3, commercial iridium oxide, and commercial ruthenium oxide in water electrolysis oxygen production tests show that at 10 mA / cm²... 2 At the same time, the overpotentials of commercial iridium oxide and commercial ruthenium oxide were 358 mV and 329 mV, respectively, while the overpotential of B-MnO2@Ir1Ru1 described in Example 3 was 230 mV. The results show that B-MnO2@Ir1Ru1 has excellent oxygen production activity in water electrolysis.

[0075] Figure 6 The performance curve of the manganese oxide-based core-shell catalyst prepared in Example 3 for PEM water electrolysis test shows that at 80℃ and 1 A / cm 2 Under current density conditions, the catalyst can operate continuously and stably for more than 800 hours without significant signs of degradation, indicating that the catalyst has superior activity and stability.

[0076] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A manganese oxide-based core-shell structured catalyst, characterized in that, It uses boron-doped manganese dioxide as the core and precious metals as the shell.

2. The manganese oxide-based core-shell catalyst according to claim 1, characterized in that, The precious metal includes at least one of iridium and ruthenium; The manganese oxide-based core-shell catalyst contains 1-10% noble metals by mass.

3. A method for preparing the manganese oxide-based core-shell structured catalyst according to claim 1 or 2, comprising the following steps: Manganese dioxide, boric acid, and ethanol are mixed and a doping reaction is carried out to obtain boron-doped manganese dioxide. The boron-doped manganese dioxide, the noble metal precursor, and water are mixed and subjected to a hydrothermal reaction to obtain the manganese oxide-based core-shell catalyst.

4. The preparation method according to claim 3, characterized in that, The manganese dioxide is nano-manganese dioxide; the microstructure of the nano-manganese dioxide includes at least one of nanoparticles, nanowires, nanotubes, nanodendritic crystals, nanoflowers, nanorods and nanostars. The molar ratio of manganese dioxide to boric acid is 0.01~100:1; The doping reaction is carried out at a temperature of 30~90℃ for a time of 0.1~48h.

5. The preparation method according to claim 3, characterized in that, The noble metal precursor includes at least one of iridium precursor and ruthenium precursor; the iridium precursor includes at least one of iridium trichloride, iridium tetrachloride and chloroiridium acid; the ruthenium precursor includes at least one of ruthenium trichloride, ruthenium acetylacetonate, potassium ruthenate, ammonium ruthenate and ruthenium acetate; The molar ratio of manganese in the boron-doped manganese dioxide to the noble metal in the noble metal precursor is 0.01~100:1; The hydrothermal reaction is carried out at a temperature of 100~300℃ for a time of 1~36h.

6. A working electrode, characterized in that, It includes a glassy carbon electrode and an active material layer located on the surface of the glassy carbon electrode. The active material layer is composed of a catalyst, conductive carbon powder, and Nafion. The catalyst is the manganese oxide-based core-shell structure catalyst according to claim 1 or 2, or the manganese oxide-based core-shell structure catalyst prepared by the preparation method according to any one of claims 3 to 5.

7. The working electrode according to claim 6, characterized in that, The mass ratio of the catalyst to the conductive carbon powder is 0.2~5:

1.

8. A method for preparing the working electrode according to claim 6 or 7, comprising the following steps: The ink is obtained by mixing the catalyst, conductive carbon powder, isopropanol, water, and Nafion solution. The ink is coated onto the upper surface of a glassy carbon electrode to obtain a working electrode.

9. The preparation method according to claim 8, characterized in that, The concentration of the catalyst in the ink is 1~5 g / L; The ink contains 10-80% isopropanol by volume and 1-10% Nafion solution by volume.

10. The application of the manganese oxide-based core-shell structure catalyst according to claim 1 or 2, the manganese oxide-based core-shell structure catalyst prepared by the preparation method according to any one of claims 3 to 5, the working electrode according to claim 6 or 7, or the working electrode prepared by the preparation method according to claim 8 or 9 in the field of hydrogen production by water electrolysis.

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