Biphase heterojunction multi-shell hollow metal oxide electrocatalyst and preparation method thereof

Abstract

The invention discloses a dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst and a preparation method thereof, and belongs to the technical field of electrocatalysts. Transition metal chromium and ruthenium are utilized to construct a metal oxide electrocatalyst with a dual-phase heterostructure, the characteristic advantages of chromium and ruthenium are effectively integrated, an electronic structure of an active site is optimized by utilizing an interface synergistic effect, and the adsorption capacity of the catalyst to a reaction intermediate is remarkably enhanced, so that the catalytic performance is remarkably improved. On the basis, glucose is further adopted as a raw material and is combined with calcination to introduce a multi-shell hollow structure, the advantages of the material are enlarged, the specific surface area of the catalyst is greatly increased through a unique multi-stage pore channel structure, rich active sites are exposed, and the mass transfer efficiency is optimized; and finally, the breakthrough of comprehensive performances such as low overpotential and excellent long cycle stability is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrocatalysts, and in particular relates to a double-phase heterojunction multi-shell hollow metal oxide electrocatalyst and a preparation method thereof. Background Art

[0002] As a key energy carrier, the large-scale production of hydrogen relies on efficient and low-cost water electrolysis technology. The water electrolysis reaction involves the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER). The slow kinetics of the four-electron transfer process in the OER seriously restricts the overall efficiency.

[0003] Currently, noble metal-based catalysts (such as Pt-based HER catalysts and IrO2 / RuO2-based OER catalysts) still maintain the highest catalytic performance, but their scarcity and high cost severely limit their industrial-scale application. In contrast, traditional transition metal oxides offer cost advantages but generally suffer from inherent drawbacks such as limited active sites, poor intrinsic conductivity, and insufficient long-term stability.

[0004] Therefore, how to use transition metal oxides to prepare catalysts with abundant active sites, low overpotential and excellent long-cycle stability has become a technical problem that needs to be solved urgently in this field. Summary of the Invention

[0005] To address the above technical issues, the present invention proposes a dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst and its preparation method. The dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst prepared by the present invention can be used in the field of alkaline water electrolysis and has low overpotential and high stability.

[0006] To achieve the above objectives, the present invention provides the following technical solutions:

[0007] The present invention provides a method for preparing a dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst, comprising the following steps:

[0008] Chromium salt and ruthenium salt are added to a glucose solution, and subjected to a hydrothermal reaction to obtain precursor microspheres; the precursor microspheres are calcined to obtain the dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst.

[0009] Technical Principle: This invention utilizes the transition metals chromium and ruthenium to construct a metal oxide electrocatalyst with a biphasic heterogeneous structure. This effectively integrates the advantageous properties of chromium and ruthenium, and utilizes interfacial synergistic effects to optimize the electronic structure of active sites, significantly enhancing the catalyst's adsorption capacity for reaction intermediates, thereby significantly improving catalytic performance. Furthermore, glucose is used as a raw material, combined with calcination, to introduce a multi-shell hollow structure, amplifying the material's advantages. The unique multi-level pore structure not only significantly increases the catalyst's specific surface area, exposing abundant active sites, but also optimizes mass transfer efficiency, ultimately achieving breakthroughs in comprehensive performance, including low overpotential and excellent long-cycle stability.

[0010] Furthermore, the molar ratio of the chromium salt to the ruthenium salt is (0.4-2): (0.4-1.4).

[0011] Furthermore, the dosage ratio of glucose to chromium salt in the glucose solution is (1-4) g: (0.4-2) mmol.

[0012] Furthermore, the temperature of the hydrothermal reaction is 120-220° C., and the time is 1-12 hours.

[0013] Furthermore, the particle size of the precursor microspheres is 1-4 μm.

[0014] Furthermore, the calcination temperature is 300-900° C., the time is 1-5 hours, and the rate of heating to the calcination temperature is 1-7° C. / min.

[0015] The present invention also provides a dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst prepared by the preparation method described in the above technical solution. The crystal phase of the dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst is a fluorite / corundum dual-phase crystal phase, and the structure is a hollow spherical, multi-shell structure.

[0016] Furthermore, the number of shell layers of the dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst is 1 to 3.

[0017] Furthermore, the particle size of the dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst is 0.8-4.0 μm.

[0018] Furthermore, the thickness of each shell of the dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst is 100-500 nm.

[0019] Compared with the prior art, the present invention has the following advantages and technical effects:

[0020] The present invention utilizes a hydrothermal reaction combined with a calcination strategy to prepare a biphasic heterojunction multi-shell hollow metal oxide electrocatalyst. First, during the hydrothermal reaction, a large number of hydroxyl groups contained in glucose are used to complex with metal ions, thereby forming amorphous carbon balls coated with a variety of metal ions. Then, the Kirkendall effect, that is, the difference in diffusion efficiency of different metal ions at high temperature will lead to the formation of a hollow structure, thereby forming a multi-shell hollow structure. The hollow multi-shell structure can effectively increase the specific surface area and the number of active sites of the metal oxide; by regulating the content of ruthenium, the evolution process of the metal oxide from a single-phase corundum-type structure to a biphasic corundum-type / fluorite-type heterostructure and then to a single-phase fluorite-type structure can be realized. The biphasic heterostructure can effectively promote the rapid conversion of intermediates and accelerate the reaction kinetics. At the same time, the introduction of the bimetallic strategy can effectively improve the stability of the electrocatalytic reaction, and finally a catalyst with rich active sites, low overpotential and excellent long-cycle stability is obtained.

[0021] The dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst prepared by the present invention has excellent electrocatalytic oxygen evolution reaction (OER) and electrocatalytic hydrogen evolution reaction (HER) performance. 2 Under these conditions, the overpotential of the electrocatalytic oxygen evolution reaction is 230~290mV, and the overpotential of the electrocatalytic hydrogen evolution reaction is 110~220mV.

[0022] The preparation method of the dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst provided by the present invention is simple in process, low in cost, and highly repeatable. The prepared dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst has a fluorite-type / corundum-type crystal phase and has a multi-shell, hollow spherical morphology structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings, which constitute part of the present invention, are provided to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are provided to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0024] Figure 1 This is the SEM image (5 μm) of the precursor microspheres prepared in Example 3;

[0025] Figure 2 This is the SEM image (3 μm) of the precursor microspheres prepared in Example 3;

[0026] Figure 3 This is a SEM image (5 μm) of the dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst prepared in Example 3;

[0027] Figure 4 This is a SEM image (2 μm) of the dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst prepared in Example 3;

[0028] Figure 5 The XRD spectrum of the dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst prepared in Example 3;

[0029] Figure 6 TEM images, HRTEM images, HADDF and EDS element distribution images of the dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst prepared in Example 3, wherein a is a TEM image, b is a HRTEM image, and c is a HADDF and EDS element distribution image;

[0030] Figure 7 LSV curves of the metal oxide catalysts prepared in Examples 2-3 and Comparative Examples 1-2, wherein a is the OER performance curve and b is the HER performance curve;

[0031] Figure 8 This is a stability test curve of the dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst prepared in Example 3. DETAILED DESCRIPTION

[0032] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0033] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0034] An embodiment of the present invention provides a method for preparing a dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst, comprising the following steps:

[0035] Chromium salt and ruthenium salt are added to a glucose solution, and subjected to a hydrothermal reaction to obtain precursor microspheres; the precursor microspheres are calcined to obtain the dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst.

[0036] In a preferred embodiment, the molar ratio of the chromium salt to the ruthenium salt is (0.4-2):(0.4-1.4), more preferably (0.8-1.6):(0.6-1.2). By regulating the ruthenium content, the present invention can achieve a change in the metal oxide structure from a single-phase corundum-type structure to a dual-phase corundum-type / fluorite-type heterostructure and then to a single-phase fluorite-type structure. Controlling the molar ratio of the chromium salt to the ruthenium salt within the above range is conducive to obtaining a metal oxide electrocatalyst having a fluorite-type / corundum-type dual-phase crystal phase.

[0037] In a preferred embodiment, the chromium salt is selected from chromium trichloride hexahydrate (CrCl 3 ·6H 2 O); and the ruthenium salt is selected from ruthenium trichloride (RuCl 3 ).

[0038] In a preferred embodiment, the ratio of glucose to chromium salt in the glucose solution is (1-4) g: (0.4-2) mmol, more preferably (1.5-3) g: (0.8-1.6) mmol.

[0039] In a preferred embodiment, the glucose solution is prepared by dispersing glucose in deionized water and stirring for 10 to 30 minutes to obtain the glucose solution; the usage ratio of the glucose to deionized water is (1 to 4) g: (30 to 60) mL.

[0040] In a preferred embodiment, the hydrothermal reaction temperature is 120-220°C, more preferably 140-180°C; the hydrothermal reaction time is 1-12 hours, more preferably 4-10 hours. During the hydrothermal reaction, the present invention utilizes the numerous hydroxyl groups contained in glucose to complex with metal ions, thereby forming amorphous carbon spheres coated with multiple metal ions.

[0041] In a preferred embodiment, after the hydrothermal reaction is completed, the steps of washing and drying are further included; the washing is suction filtration washing; the drying temperature is 30-60° C., the time is 1-10 hours, and the equipment is an oven.

[0042] In a preferred embodiment, the particle size of the precursor microspheres is 1-4 μm.

[0043] In a preferred embodiment, the calcination temperature is 300-900°C, more preferably 400-700°C; the calcination time is 1-5 hours, more preferably 2-3 hours; and the heating rate to the calcination temperature is 1-7°C / min, more preferably 2-5°C / min. The present invention controls the diffusion rate of different metal ions by regulating the calcination temperature and heating rate, thereby forming a multi-shell hollow structure. This hollow multi-shell structure can effectively increase the specific surface area and the number of active sites of the metal oxide.

[0044] The present invention also provides a dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst prepared by the preparation method described in the above technical solution. The dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst has a fluorite / corundum dual-phase crystal phase and a hollow spherical, multi-shell structure. The introduction of the hollow structure and dual-phase crystal phase gives the metal oxide electrocatalyst excellent water electrolysis performance.

[0045] In a preferred embodiment, the dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst has 1 to 3 shells. When the shell number is 1, it is composed of a fluorite / corundum dual-phase heterostructure (RuO2 / Cr2O3); when the shell number is greater than 1, each layer has the same composition, and is a fluorite / corundum dual-phase heterostructure.

[0046] In a preferred embodiment, the particle size of the dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst is 0.8-4.0 μm.

[0047] In a preferred embodiment, the thickness of each shell of the dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst is 100-500 nm.

[0048] The room temperature in the embodiments of the present invention refers to "25±2°C".

[0049] Unless otherwise specified, the raw materials in the examples of the present invention were purchased from commercial sources.

[0050] Example 1

[0051] A method for preparing a dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst, comprising the following steps:

[0052] 1.0 g of anhydrous glucose was dispersed in 30 mL of deionized water and stirred for 10 minutes to obtain an anhydrous glucose solution. 0.4 mmol of chromium chloride hexahydrate (CrCl3·6H2O) and 0.4 mmol of ruthenium chloride (RuCl3) were added to the anhydrous glucose solution, mixed thoroughly, and transferred to a 100 mL polytetrafluoroethylene reactor. The mixture was heated to 120°C and reacted for 12 hours. After cooling to room temperature, the mixture was filtered and washed, and then dried in a 30°C oven for 10 hours to obtain precursor microspheres with a particle size of 1-4 μm. The precursor microspheres were calcined in a muffle furnace at 300°C for 5 hours, with the temperature increasing to the calcination temperature at a rate of 1°C / min. The resulting product is a dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst, designated RuO2 / Cr2O3.

[0053] The crystal phase of the above-mentioned dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst is a fluorite / corundum dual-phase crystal phase, and the structure is a hollow spherical, multi-shell structure with 3 shells. The thickness of each shell is 150~200nm, and the particle size of the catalyst is 1.5~4.0μm.

[0054] Example 2

[0055] A method for preparing a dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst, comprising the following steps:

[0056] 1.5 g of anhydrous glucose was dispersed in 30 mL of deionized water and stirred for 10 minutes to obtain an anhydrous glucose solution. 0.8 mmol of chromium trichloride hexahydrate (CrCl3·6H2O) and 0.6 mmol of ruthenium trichloride (RuCl3) were added to the anhydrous glucose solution, mixed thoroughly, and transferred to a 100 mL polytetrafluoroethylene reactor. The reaction was heated to 140°C for 10 hours. After cooling to room temperature, the mixture was filtered, washed, and dried in a 40°C oven for 8 hours to obtain precursor microspheres with a particle size of 1-4 μm. The precursor microspheres were calcined in a muffle furnace at 400°C for 3 hours, with the temperature increasing to the calcination temperature at a rate of 2°C / min. The resulting product was a dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst, designated RuO2 / Cr2O3-2.

[0057] The crystal phase of the above-mentioned dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst is a fluorite / corundum dual-phase crystal phase, and the structure is a hollow spherical, multi-shell structure with 2 shell layers. The thickness of each shell layer is 150~300nm, and the particle size of the catalyst is 1.2~2.8μm.

[0058] Example 3

[0059] A method for preparing a dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst, comprising the following steps:

[0060] 1.8 g of anhydrous glucose was dispersed in 30 mL of deionized water and stirred for 10 minutes to obtain an anhydrous glucose solution. 1.2 mmol of chromium chloride hexahydrate (CrCl3·6H2O) and 0.8 mmol of ruthenium chloride (RuCl3) were added to the anhydrous glucose solution, mixed thoroughly, and transferred to a 100 mL polytetrafluoroethylene reactor. The reaction was heated to 160°C for 6 hours. After cooling to room temperature, the mixture was filtered, washed, and dried in a 60°C oven for 4 hours to obtain precursor microspheres with a particle size of 1-4 μm. The precursor microspheres were calcined in a muffle furnace at 600°C for 3 hours, with the temperature increasing to the calcination temperature at a rate of 3°C / min. The resulting product was a dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst, designated RuO2 / Cr2O3-1.

[0061] The crystal phase of the above-mentioned dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst is a fluorite / corundum dual-phase crystal phase, and the structure is a hollow spherical, multi-shell structure with 3 shells. The thickness of each shell is 100~500nm, and the particle size of the catalyst is 1.8~3.7μm.

[0062] Figure 1 This is the SEM image (5 μm) of the precursor microspheres prepared in Example 3. Figure 2 This is the SEM image (3 μm) of the precursor microspheres prepared in Example 3. Figure 1 and Figure 2It can be seen from the figure that the precursor microspheres prepared by the method of the present invention are spherical structures.

[0063] Figure 3 This is the SEM image (5 μm) of the dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst prepared in Example 3. Figure 4 This is a SEM image (2 μm) of the dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst prepared in Example 3. Figure 3 and Figure 4 It can be seen from the figure that the dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst prepared in Example 3 has uniform morphology and size, forms a clear hollow structure, and its shell is dense.

[0064] Figure 5 The XRD spectrum of the double-phase heterojunction multi-shell hollow metal oxide electrocatalyst prepared in Example 3. Figure 5 It can be seen that the dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst prepared in Example 3 is a dual-phase heterostructure of a fluorite-type structure and a corundum-type structure.

[0065] Figure 6 TEM images, HRTEM images, HADDF and EDS element distribution images of the dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst prepared in Example 3, wherein a is a TEM image, b is a HRTEM image, and c is a HADDF and EDS element distribution image. Figure 6 As can be seen from part a of FIG, the double-phase heterojunction multi-shell hollow metal oxide electrocatalyst prepared in Example 3 is a hollow core-shell structure with three shell layers. Figure 6 As can be seen from part b in Example 3, the dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst prepared in Example 3 forms a fluorite / corundum dual-phase structure. Figure 6 As can be seen from part c in Figure 1, the dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst contains Cr, Ru and O elements.

[0066] Example 4

[0067] A method for preparing a dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst, comprising the following steps:

[0068] 3g of anhydrous glucose was dispersed in 30mL of deionized water and stirred for 10 minutes to obtain an anhydrous glucose solution. 1.6mmol of chromium trichloride hexahydrate (CrCl3·6H2O) and 1.2mmol of ruthenium trichloride (RuCl3) were added to the anhydrous glucose solution, mixed thoroughly, and transferred to a 100mL polytetrafluoroethylene reactor. The mixture was heated to 180°C and reacted for 4 hours. After cooling to room temperature, the mixture was filtered and washed, and then dried in a 60°C oven for 2 hours to obtain precursor microspheres with a particle size of 1-4μm. The precursor microspheres were calcined in a muffle furnace at 700°C for 2 hours, with the temperature increasing to the calcination temperature at a rate of 5°C / min. The resulting product is a dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst.

[0069] The crystal phase of the above-mentioned dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst is a fluorite / corundum dual-phase crystal phase, and the structure is a hollow spherical, multi-shell structure with 3 shells. The thickness of each shell is 100~300nm, and the particle size of the catalyst is 1.5~3.0μm.

[0070] Example 5

[0071] A method for preparing a dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst, comprising the following steps:

[0072] 4 g of anhydrous glucose was dispersed in 30 mL of deionized water and stirred for 10 minutes to obtain an anhydrous glucose solution. 2 mmol of chromium trichloride hexahydrate (CrCl3·6H2O) and 1.4 mmol of ruthenium trichloride (RuCl3) were added to the anhydrous glucose solution, mixed thoroughly, and transferred to a 100 mL polytetrafluoroethylene reactor. The reaction was heated to 220°C for 1 hour. After cooling to room temperature, the mixture was filtered and washed, and then dried in a 50°C oven for 7 hours to obtain precursor microspheres with a particle size of 1-4 μm. The precursor microspheres were calcined in a muffle furnace at 900°C for 1 hour, with the temperature increasing to the calcination temperature at a rate of 7°C / min. The resulting product was a dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst.

[0073] The crystal phase of the above-mentioned dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst is a fluorite / corundum dual-phase crystal phase, the structure is a hollow spherical, multi-shell structure, the number of shells is 2 layers, the thickness of each shell is 200~400nm, and the particle size of the catalyst is 2.0~3.5μm.

[0074] Example 6

[0075] 1.8 g of anhydrous glucose was dispersed in 30 mL of deionized water and stirred for 10 minutes to obtain an anhydrous glucose solution. 1.65 mmol of chromium chloride hexahydrate (CrCl3·6H2O) and 1.2 mmol of ruthenium chloride (RuCl3) were added to the anhydrous glucose solution, mixed thoroughly, and transferred to a 100 mL polytetrafluoroethylene reactor. The mixture was heated to 160°C and reacted for 12 hours. After cooling to room temperature, the mixture was filtered and washed, and then dried in a 60°C oven for 3 hours to obtain precursor microspheres with a particle size of 1-4 μm. The precursor microspheres were calcined in a muffle furnace at 700°C for 3 hours, with the temperature increasing to the calcination temperature at a rate of 3°C / min. The resulting product was a fluorite / corundum biphasic hollow metal oxide catalyst, designated RuO2 / Cr2O3-3.

[0076] The crystal phase of the above-mentioned fluorite / corundum dual-phase hollow metal oxide catalyst is a fluorite / corundum dual-phase crystal phase, and the structure is a hollow spherical, multi-shell structure with 1 to 3 shell layers. Some areas are single-layer or double-layer, and the structure is uneven. The thickness of each shell layer is 200 to 400 nm, and the particle size of the catalyst is 1.5 to 3.0 μm.

[0077] Comparative Example 1

[0078] 1.8 g of anhydrous glucose was dispersed in 30 mL of deionized water and stirred for 10 minutes to obtain an anhydrous glucose solution. 1.65 mmol of chromium chloride hexahydrate (CrCl3·6H2O) and 0.1 mmol of ruthenium chloride (RuCl3) were added to the anhydrous glucose solution, mixed thoroughly, and transferred to a 100 mL polytetrafluoroethylene reactor. The reaction was heated to 160°C for 12 hours. After cooling to room temperature, the mixture was filtered, washed, and dried in a 60°C oven for 3 hours to obtain precursor microspheres with a particle size of 1-4 μm. The precursor microspheres were calcined in a muffle furnace at 700°C for 3 hours, with the temperature increasing to the calcination temperature at a rate of 3°C / min. The resulting product was a single-phase corundum-type metal oxide catalyst, designated as Cr2O3.

[0079] The single-phase corundum-type metal oxide catalyst has a single-phase corundum-type crystal phase, a hollow spherical structure, a single-shell structure, one shell layer, a shell thickness of 300-500 nm, and a particle size of 1.0-2.5 μm.

[0080] In Comparative Example 1, since the amount of ruthenium trichloride added is too small, the ruthenium content in the precursor microspheres is extremely low, and it is difficult to form an independent RuO2 crystal phase at high temperature, so only a single-phase Cr2O3 is formed.

[0081] Comparative Example 2

[0082] 1.8 g of anhydrous glucose was dispersed in 30 mL of deionized water and stirred for 10 minutes to obtain an anhydrous glucose solution. 1.65 mmol of chromium chloride hexahydrate (CrCl3·6H2O) and 1.6 mmol of ruthenium chloride (RuCl3) were added to the anhydrous glucose solution, mixed thoroughly, and transferred to a 100 mL polytetrafluoroethylene reactor. The mixture was heated to 160°C and reacted for 12 hours. After cooling to room temperature, the mixture was filtered, washed, and dried in a 60°C oven for 3 hours to obtain precursor microspheres with a particle size of 1-4 μm. The precursor microspheres were calcined in a muffle furnace at 700°C for 3 hours, with the temperature increasing to the calcination temperature at a rate of 3°C / min. The resulting product was a single-phase fluorite-type metal oxide catalyst, designated RuO2.

[0083] The single-phase fluorite-type metal oxide catalyst has a fluorite-type single-phase crystal phase, a hollow spherical structure, a single-shell structure, one shell layer, a shell thickness of 100-300 nm, and a particle size of 2.0-3.5 μm.

[0084] In Comparative Example 2, since the amount of ruthenium trichloride added was too high, the Cr2O3 phase was suppressed, and thus only a single phase of RuO2 was formed.

[0085] The metal oxide catalysts prepared in Examples 1-6 and Comparative Examples 1-2 were ground for 1 hour, and then 10 mg of the ground sample, 1 mL of a mixed solution of water and isopropanol (volume ratio of water to isopropanol: 3:1), and 50 μL of Nafion solution were mixed and ultrasonically dispersed for 30 minutes to obtain a dispersion. 10 μL of the dispersion was applied to a 3 mm diameter, approximately 0.07 cm area. 2 The surface of the glassy carbon electrode was dried at room temperature to obtain a metal oxide catalyst working electrode.

[0086] In an environment of 25±1℃, a three-electrode system was composed of 1 mol / L KOH solution as the electrolyte, a graphite rod as the counter electrode, Ag / AgCl as the reference electrode, and the above-mentioned metal oxide catalyst working electrode to carry out the electrolysis water performance test. The linear scan rate was 5 mV / s, the OER test voltage range was 0 V to 0.8 V, and the HER test voltage range was -0.8 V to -1.6 V.

[0087] Figure 7 LSV curves of the metal oxide catalysts prepared in Examples 2-3 and Comparative Examples 1-2, where a is the OER performance curve and b is the HER performance curve. Figure 7 The horizontal axis is the potential of the working electrode relative to the reference electrode (vs. RHE), and the overpotential is the difference between the actual test potential and the thermodynamic equilibrium potential of the reaction (1.23V vs. RHE under standard conditions for OER). Figure 7The potential obtained from the horizontal axis minus 1.23V is the OER overpotential. Figure 7 It can be seen that compared with the metal oxide catalyst prepared in the comparative example, the dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst prepared in Example 3 exhibits excellent oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) catalytic performance. 2 At a current density of 1.5 Å, the OER overpotential is 234 mV and the HER overpotential is 114 mV.

[0088] The stability of the double-phase heterojunction multi-shell hollow metal oxide electrocatalyst prepared in Example 3 was tested at a voltage of 1.55 V in 1 M KOH. Figure 8 . Figure 8 This is the stability test curve of the double-phase heterojunction multi-shell hollow metal oxide electrocatalyst prepared in Example 3. Figure 8 It can be seen that at a test voltage of 1.55V, the catalyst can operate stably for more than 30 hours without any attenuation of the current density, indicating that it has high stability.

[0089] The electrocatalytic performance results of Examples 1-6 and Comparative Examples 1-2 are shown in Table 1.

[0090] Table 1

[0091]

[0092] In the table, “—” indicates that the catalyst cannot reach 10 mA / cm within the tested potential range. 2 The current density of 1.5 Å indicates that its catalytic activity is extremely low and it cannot effectively promote the OER and HER reactions.

[0093] It can be found from Table 1 that the introduction of the hollow structure and the dual-phase crystal phase makes the dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst have excellent electrolytic water performance. 2 At a current density of 1.5 Å, the OER overpotential is 234 mV and the HER overpotential is 114 mV.

[0094] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A method for preparing a dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst, characterized in that: The following steps are involved: Chromium salt and ruthenium salt are added to glucose solution and subjected to hydrothermal reaction to obtain precursor microspheres; The precursor microspheres are calcined to obtain the dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst.

2. The method for preparing a dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst according to claim 1, characterized in that: The molar ratio of the chromium salt to the ruthenium salt is (0.4-2): (0.4-1.4).

3. The method for preparing a dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst according to claim 1, characterized in that: The dosage ratio of glucose to chromium salt in the glucose solution is (1-4) g: (0.4-2) mmol.

4. The method for preparing a dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst according to claim 1, characterized in that: The temperature of the hydrothermal reaction is 120-220° C., and the time is 1-12 hours.

5. The method for preparing a dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst according to claim 1, characterized in that: The particle size of the precursor microspheres is 1-4 μm.

6. The method for preparing a dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst according to claim 1, characterized in that: The calcination temperature is 300-900° C., the time is 1-5 hours, and the rate of heating to the calcination temperature is 1-7° C. / min.

7. A dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst prepared by the preparation method according to any one of claims 1 to 6, characterized in that: The crystal phase of the dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst is a fluorite-type / corundum-type dual-phase crystal phase, and the structure is a hollow spherical multi-shell structure.

8. The dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst according to claim 7, characterized in that: The number of shell layers of the double-phase heterojunction multi-shell hollow metal oxide electrocatalyst is 1 to 3.

9. The dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst according to claim 7, characterized in that: The particle size of the dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst is 0.8-4.0 μm.

10. The dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst according to claim 7, characterized in that: The thickness of each shell of the dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst is 100-500 nm.

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