A dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst and its preparation method

Abstract

This invention discloses a biphase heterojunction multi-shell hollow metal oxide electrocatalyst and its preparation method, belonging to the field of electrocatalyst technology. This invention utilizes transition metals chromium and ruthenium to construct a metal oxide electrocatalyst with a biphase heterostructure, effectively integrating the advantages of chromium and ruthenium. Furthermore, it optimizes the electronic structure of active sites using interfacial synergistic effects, significantly enhancing the catalyst's adsorption capacity for reaction intermediates, thereby significantly improving catalytic performance. Building upon this, glucose is further used as a raw material, combined with calcination to introduce a multi-shell hollow structure, amplifying the material's advantages. The unique hierarchical porous structure not only significantly increases the catalyst's specific surface area and exposes abundant active sites but also optimizes mass transfer efficiency, ultimately achieving breakthroughs in comprehensive performance such as low overpotential and excellent long-cycle stability.

Description

Technical Field

[0001] This invention belongs to the field of electrocatalyst technology, and particularly relates to a two-phase heterojunction multi-shell hollow metal oxide electrocatalyst and its preparation method. Background Technology

[0002] Hydrogen energy, as a key energy carrier, relies on efficient and low-cost water electrolysis technology for its large-scale production. The water electrolysis reaction involves the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER), among which the four-electron transfer process in the OER is kineticly slow, which severely limits the overall efficiency.

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

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

[0005] To address the aforementioned technical problems, this invention proposes a biphase heterojunction multi-shell hollow metal oxide electrocatalyst and its preparation method. The biphase heterojunction multi-shell hollow metal oxide electrocatalyst prepared by this invention can be used in alkaline water electrolysis, exhibiting low overpotential and high stability.

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

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

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

[0009] Technical Principle: This invention utilizes transition metals chromium and ruthenium to construct a metal oxide electrocatalyst with a dual-phase heterostructure, effectively integrating the advantages of chromium and ruthenium. Furthermore, the electronic structure of the active sites is optimized using interfacial synergistic effects, significantly enhancing the catalyst's adsorption capacity for reaction intermediates, thereby significantly improving catalytic performance. Building upon this, glucose is further used as a raw material, and calcination introduces a multi-shell hollow structure, amplifying the material's advantages. The unique hierarchical porous structure not only significantly increases the catalyst's specific surface area and exposes abundant active sites but also optimizes mass transfer efficiency, ultimately achieving breakthroughs in comprehensive performance such as 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 ratio of glucose to chromium salt in the glucose solution is (1~4) g : (0.4~2) mmol.

[0012] Furthermore, the hydrothermal reaction is carried out at a temperature of 120~220℃ for a time of 1~12h.

[0013] Furthermore, the precursor microspheres have a particle size of 1~4μm.

[0014] Furthermore, the calcination temperature is 300~900℃, the time is 1~5h, and the rate of heating to the calcination temperature is 1~7℃ / min.

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

[0016] Furthermore, the number of shells in 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 layer of the dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst is 100~500nm.

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

[0020] This invention utilizes a hydrothermal reaction combined with a calcination strategy to prepare a biphase heterojunction multi-shell hollow metal oxide electrocatalyst. First, during the hydrothermal reaction, the numerous hydroxyl groups in glucose complex with metal ions, forming amorphous carbon spheres coated with various metal ions. Then, leveraging the Kirkendall effect—the difference in diffusion efficiency of different metal ions at high temperatures leading to the formation of hollow structures—a multi-shell hollow structure is created. This hollow multi-shell structure effectively increases the specific surface area and the number of active sites of the metal oxide. By controlling the ruthenium content, the metal oxide can evolve from a single-phase corundum structure to a biphase corundum / fluorite heterostructure and then back to a single-phase fluorite structure. The biphase heterostructure effectively promotes the rapid conversion of intermediates and accelerates reaction kinetics. Simultaneously, the introduction of a bimetallic strategy effectively improves the stability of the electrocatalytic reaction, ultimately yielding a catalyst with abundant active sites, low overpotential, and excellent long-term cycling stability.

[0021] The biphase heterojunction multi-shell hollow metal oxide electrocatalyst prepared in this invention exhibits excellent electrocatalytic oxygen evolution reaction (OER) and electrocatalytic hydrogen evolution reaction (HER) performance at 10 mA / cm². 2 Under the given conditions, the overpotential for the electrocatalytic oxygen evolution reaction is 230~290mV, and the overpotential for the electrocatalytic hydrogen evolution reaction is 110~220mV.

[0022] The preparation method of the biphase heterojunction multi-shell hollow metal oxide electrocatalyst provided by the present invention is simple, low in cost, and highly reproducible. The prepared biphase heterojunction multi-shell hollow metal oxide electrocatalyst has fluorite / corundum crystal phases and a multi-shell, hollow spherical morphology. Attached Figure Description

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

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

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

[0026] Figure 3 SEM image (5 μm) of the biphase heterojunction multi-shell hollow metal oxide electrocatalyst prepared in Example 3.

[0027] Figure 4 SEM image (2 μm) of the biphase heterojunction multi-shell hollow metal oxide electrocatalyst prepared in Example 3.

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

[0029] Figure 6 TEM image, HRTEM image, and elemental distribution diagrams of HADDF and EDS for the biphase heterojunction multi-shell hollow metal oxide electrocatalyst prepared in Example 3 are shown. In the figure, a is the TEM image, b is the HRTEM image, and c is the elemental distribution diagram of HADDF and EDS.

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

[0031] Figure 8 The stability test curve of the biphase heterojunction multi-shell hollow metal oxide electrocatalyst prepared in Example 3 is shown. Detailed Implementation

[0032] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0034] This invention provides a method for preparing a two-phase heterojunction multi-shell hollow metal oxide electrocatalyst, comprising the following steps:

[0035] Chromium salt and ruthenium salt were added to a glucose solution and subjected to a hydrothermal reaction to obtain precursor microspheres; the precursor microspheres were then calcined to obtain the biphase 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 controlling the ruthenium content, this invention can achieve the transformation of the metal oxide from a single-phase corundum structure to a dual-phase corundum / fluorite heterostructure and then back to a single-phase fluorite structure. Controlling the molar ratio of the chromium salt to the ruthenium salt within the aforementioned range is beneficial for obtaining metal oxide electrocatalysts with a fluorite / corundum dual-phase crystal phase.

[0037] In a preferred embodiment, the chromium salt is selected from chromium trichloride hexahydrate (CrCl3·6H2O); the ruthenium salt is selected from ruthenium trichloride (RuCl3).

[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 10-30 minutes to obtain the glucose solution; the ratio of glucose to deionized water is (1-4) g: (30-60) mL.

[0040] In a preferred embodiment, the temperature of the hydrothermal reaction is 120~220℃, more preferably 140~180℃; the time of the hydrothermal reaction is 1~12h, more preferably 4~10h. In this invention, the numerous hydroxyl groups contained in glucose are used to complex with metal ions during the hydrothermal reaction, thereby forming amorphous carbon spheres coated with various metal ions.

[0041] In a preferred embodiment, the process further includes washing and drying steps after the hydrothermal reaction is completed; the washing is vacuum filtration washing; the drying temperature is 30~60℃, the time is 1~10h, and the equipment is an oven.

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

[0043] In a preferred embodiment, the calcination temperature is 300-900℃, more preferably 400-700℃; the calcination time is 1-5 hours, more preferably 2-3 hours; and the heating rate to the calcination temperature is 1-7℃ / min, more preferably 2-5℃ / min. This 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] This invention also provides a biphase heterojunction multi-shell hollow metal oxide electrocatalyst prepared by the preparation method described above. The crystal phase of the biphase heterojunction multi-shell hollow metal oxide electrocatalyst is a fluorite / corundum biphase crystal phase, and the structure is a hollow spherical, multi-shell structure. The introduction of the hollow structure and biphase crystal phase gives the metal oxide electrocatalyst excellent water electrolysis performance.

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

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

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

[0048] In this embodiment of the invention, room temperature refers to "25±2℃".

[0049] Unless otherwise specified, all raw materials used in the embodiments of this invention were purchased through commercial channels.

[0050] Example 1

[0051] A method for preparing a two-phase heterojunction multi-shell hollow metal oxide electrocatalyst, the specific steps of which are as follows:

[0052] 1.0 g of anhydrous glucose was dispersed in 30 mL of deionized water and stirred for 10 min to obtain an anhydrous glucose solution. 0.4 mmol of chromium trichloride hexahydrate (CrCl3·6H2O) and 0.4 mmol of ruthenium trichloride (RuCl3) were added to the anhydrous glucose solution, mixed thoroughly, and then transferred to a 100 mL polytetrafluoroethylene reactor. The mixture was heated to 120 °C and reacted for 12 h. After cooling to room temperature, the mixture was filtered, washed, and dried in a 30 °C oven for 10 h 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 h, with a heating rate of 1 °C / min. The resulting product was a biphase heterojunction multi-shell hollow metal oxide electrocatalyst, denoted as RuO2 / Cr2O3.

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

[0054] Example 2

[0055] A method for preparing a two-phase heterojunction multi-shell hollow metal oxide electrocatalyst, the specific steps of which are as follows:

[0056] 1.5 g of anhydrous glucose was dispersed in 30 mL of deionized water and stirred for 10 min 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 then transferred to a 100 mL polytetrafluoroethylene reactor. The mixture was heated to 140 °C and reacted for 10 h. After cooling to room temperature, the mixture was filtered, washed, and dried in a 40 °C oven for 8 h 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 h, with a heating rate of 2 °C / min. The resulting product was a biphase heterojunction multi-shell hollow metal oxide electrocatalyst, denoted as RuO2 / Cr2O3-2.

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

[0058] Example 3

[0059] A method for preparing a two-phase heterojunction multi-shell hollow metal oxide electrocatalyst, the specific steps of which are as follows:

[0060] 1.8 g of anhydrous glucose was dispersed in 30 mL of deionized water and stirred for 10 min to obtain an anhydrous glucose solution. 1.2 mmol of chromium trichloride hexahydrate (CrCl3·6H2O) and 0.8 mmol of ruthenium trichloride (RuCl3) were added to the anhydrous glucose solution, mixed thoroughly, and then transferred to a 100 mL polytetrafluoroethylene reactor. The mixture was heated to 160 °C and reacted for 6 h. After cooling to room temperature, the mixture was filtered, washed, and dried in a 60 °C oven for 4 h 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 h, with a heating rate of 3 °C / min. The resulting product was a biphase heterojunction multi-shell hollow metal oxide electrocatalyst, denoted as RuO2 / Cr2O3-1.

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

[0062] Figure 1 SEM image (5 μm) of the precursor microspheres prepared in Example 3. Figure 2 SEM image (3 μm) of the precursor microspheres prepared in Example 3. Figure 1 and Figure 2As can be seen from the above, the precursor microspheres prepared by the method of the present invention have a spherical structure.

[0063] Figure 3 The image shows a SEM image (5 μm) of the biphase heterojunction multi-shell hollow metal oxide electrocatalyst prepared in Example 3. Figure 4 SEM image (2 μm) of the biphase heterojunction multi-shell hollow metal oxide electrocatalyst prepared in Example 3. From... Figure 3 and Figure 4 As can be seen from the example, the biphase heterojunction multi-shell hollow metal oxide electrocatalyst prepared in Example 3 has a uniform morphology and size, forms an obvious hollow structure, and its shell is dense.

[0064] Figure 5 The image shows the XRD pattern of the biphase heterojunction multi-shell hollow metal oxide electrocatalyst prepared in Example 3. Figure 5 It can be seen that the biphase heterojunction multi-shell hollow metal oxide electrocatalyst prepared in Example 3 is a biphase heterostructure with fluorite and corundum structures.

[0065] Figure 6 The images show TEM, HRTEM, and elemental distribution maps of HADDF and EDS for the biphase heterojunction multi-shell hollow metal oxide electrocatalyst prepared in Example 3. In the images, a is a TEM image, b is an HRTEM image, and c is an elemental distribution map of HADDF and EDS. Figure 6 As can be seen from part a in Example 3, the biphase heterojunction multi-shell hollow metal oxide electrocatalyst prepared in Example 3 has a hollow core-shell structure with three shell layers. Figure 6 As can be seen from part b, the biphase heterojunction multi-shell hollow metal oxide electrocatalyst prepared in Example 3 formed a fluorite / corundum biphase structure. From Figure 6 As can be seen from part c, 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 two-phase heterojunction multi-shell hollow metal oxide electrocatalyst, the specific steps of which are as follows:

[0068] 3 g of anhydrous glucose was dispersed in 30 mL of deionized water and stirred for 10 min to obtain an anhydrous glucose solution. 1.6 mmol of chromium trichloride hexahydrate (CrCl3·6H2O) and 1.2 mmol of ruthenium trichloride (RuCl3) were added to the anhydrous glucose solution, mixed thoroughly, and then transferred to a 100 mL polytetrafluoroethylene reactor. The mixture was heated to 180 °C and reacted for 4 h. After cooling to room temperature, the mixture was filtered, washed, and dried in a 60 °C oven for 2 h 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 2 h, with the temperature increased to the calcination temperature at a rate of 5 °C / min. The resulting product is the biphase 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 fluorite-type / corundum-type dual-phase crystal phase, and the structure is a hollow sphere with a multi-shell structure. There are 3 shell layers, and the thickness of each shell layer is 100~300nm. The particle size of the catalyst is 1.5~3.0μm.

[0070] Example 5

[0071] A method for preparing a two-phase heterojunction multi-shell hollow metal oxide electrocatalyst, the specific steps of which are as follows:

[0072] 4 g of anhydrous glucose was dispersed in 30 mL of deionized water and stirred for 10 min 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 then transferred to a 100 mL polytetrafluoroethylene reactor. The mixture was heated to 220 °C and reacted for 1 h. After cooling to room temperature, the mixture was filtered, washed, and dried in a 50 °C oven for 7 h 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 h, with a heating rate of 7 °C / min. The resulting product was a biphase 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 fluorite-type / corundum-type dual-phase crystal phase, and the structure is a hollow sphere with a multi-shell structure. There are two shells, and the thickness of each shell is 200~400nm. 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 min to obtain an anhydrous glucose solution. 1.65 mmol of chromium trichloride hexahydrate (CrCl3·6H2O) and 1.2 mmol of ruthenium trichloride (RuCl3) were added to the anhydrous glucose solution, mixed thoroughly, and then transferred to a 100 mL polytetrafluoroethylene reactor. The mixture was heated to 160 °C and reacted for 12 h. After cooling to room temperature, the mixture was filtered, washed, and dried in a 60 °C oven for 3 h 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 h, with a heating rate of 3 °C / min. The resulting product was a fluorite / corundum type dual-phase hollow metal oxide catalyst, denoted as RuO2 / Cr2O3-3.

[0076] The crystal phase of the above-mentioned fluorite / corundum biphase hollow metal oxide catalyst is fluorite / corundum biphase crystal phase, with a hollow spherical, multi-shell structure, with 1 to 3 shell layers, some regions being single or double layers, and the structure is non-uniform. 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 min to obtain an anhydrous glucose solution. 1.65 mmol of chromium trichloride hexahydrate (CrCl3·6H2O) and 0.1 mmol of ruthenium trichloride (RuCl3) were added to the anhydrous glucose solution, mixed thoroughly, and then transferred to a 100 mL polytetrafluoroethylene reactor. The mixture was heated to 160 °C and reacted for 12 h. After cooling to room temperature, the mixture was filtered, washed, and dried in a 60 °C oven for 3 h 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 h, with a heating rate of 3 °C / min. The resulting product was a single-phase corundum-type metal oxide catalyst, denoted as Cr2O3.

[0079] The crystal phase of the above-mentioned single-phase corundum metal oxide catalyst is a single-phase corundum crystal phase with a hollow spherical, single-shell structure. The number of shells is 1, the shell thickness is 300~500nm, and the particle size of the catalyst is 1.0~2.5μm.

[0080] In Comparative Example 1, due to the insufficient addition of ruthenium trichloride, the ruthenium content in the precursor microspheres was extremely low, making it difficult to form an independent RuO2 crystal phase at high temperatures. Therefore, only a single-phase Cr2O3 was formed.

[0081] Comparative Example 2

[0082] 1.8 g of anhydrous glucose was dispersed in 30 mL of deionized water and stirred for 10 min to obtain an anhydrous glucose solution. 1.65 mmol of chromium trichloride hexahydrate (CrCl3·6H2O) and 1.6 mmol of ruthenium trichloride (RuCl3) were added to the anhydrous glucose solution, mixed thoroughly, and then transferred to a 100 mL polytetrafluoroethylene reactor. The mixture was heated to 160 °C and reacted for 12 h. After cooling to room temperature, the mixture was filtered, washed, and dried in a 60 °C oven for 3 h 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 h, with a heating rate of 3 °C / min. The resulting product was a single-phase fluorite-type metal oxide catalyst, denoted as RuO2.

[0083] The crystal phase of the above-mentioned single-phase fluorite metal oxide catalyst is a single-phase fluorite crystal phase with a hollow spherical, single-shell structure. The number of shells is 1, the shell thickness is 100~300nm, and the particle size of the catalyst is 2.0~3.5μm.

[0084] In Comparative Example 2, the excessive addition of ruthenium trichloride suppressed the Cr2O3 phase, resulting in the formation of only a single-phase RuO2.

[0085] The metal oxide catalysts prepared in Examples 1-6 and Comparative Examples 1-2 were ground for 1 hour each. 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 this dispersion was then coated onto a surface with a diameter of 3 mm and an area of ​​approximately 0.07 cm². 2 The glassy carbon electrode surface is dried at room temperature to obtain a metal oxide catalyst working electrode.

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

[0087] Figure 7 The LSV curves of the metal oxide catalysts prepared in Examples 2-3 and Comparative Examples 1-2 are shown, where a is the OER performance curve and b is the HER performance curve. Figure 7 The horizontal axis represents the potential of the working electrode relative to the reference electrode (vs. RHE), and the overpotential is the difference between the actual measured potential and the reaction thermodynamic equilibrium potential (OER is 1.23V vs. RHE under standard conditions). Therefore, according to... Figure 7The potential obtained from the horizontal axis minus 1.23V is the OER overpotential. From Figure 7 As can be seen, compared with the metal oxide catalyst prepared in the comparative example, the biphase heterojunction multi-shell hollow metal oxide electrocatalyst prepared in Example 3 exhibits superior oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) catalytic performance at 10 mA / cm². 2 At the given current density, the OER overpotential is 234 mV, and the HER overpotential is 114 mV.

[0088] The stability of the biphase heterojunction multi-shell hollow metal oxide electrocatalyst prepared in Example 3 was tested in 1M KOH at a voltage of 1.55V. The results are shown in [Figure 1]. Figure 8 . Figure 8 The stability test curves for the biphase heterojunction multi-shell hollow metal oxide electrocatalyst prepared in Example 3 are shown. Figure 8 It can be seen that the catalyst can operate stably for more than 30 hours under a test voltage of 1.55V, and the current density does not decay, 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 low current density indicates that its catalytic activity is extremely low and it cannot effectively promote the OER and HER reactions.

[0093] Table 1 shows that the introduction of hollow structure and dual-phase crystal phase gives the dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst excellent water electrolysis performance. Example 3 demonstrates this at 10 mA / cm². 2 At the given current density, 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 variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing a two-phase heterojunction multi-shell hollow metal oxide electrocatalyst, characterized in that, Includes the following steps: Chromium and ruthenium salts were added to a glucose solution and subjected to a hydrothermal reaction to obtain precursor microspheres. The precursor microspheres were calcined to obtain the biphase heterojunction multi-shell hollow metal oxide electrocatalyst; the molar ratio of the chromium salt and the ruthenium salt was 1.2:0.8; the chromium salt was selected from chromium trichloride hexahydrate; the ruthenium salt was selected from ruthenium trichloride. 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.

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

3. The method for preparing a dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst according to claim 1, characterized in that, The hydrothermal reaction is carried out at a temperature of 120~220℃ for 1~12 hours.

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

5. 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℃, the time is 1~5h, and the rate of heating to the calcination temperature is 1~7℃ / min.

6. A biphase heterojunction multi-shell hollow metal oxide electrocatalyst prepared by the preparation method according to any one of claims 1 to 5, characterized in that, 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.

7. The dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst according to claim 6, characterized in that, The number of shells in the biphase heterojunction multi-shell hollow metal oxide electrocatalyst is 1 to 3.

8. The dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst according to claim 6, characterized in that, The particle size of the biphase heterojunction multi-shell hollow metal oxide electrocatalyst is 0.8~4.0 μm.

9. The dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst according to claim 6, characterized in that, The thickness of each shell layer of the dual-phase heterojunction multi-shell hollow metal oxide electrocatalyst is 100~500nm.

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