Two-phase hollow high-entropy oxide catalyst as well as preparation method and application thereof

Abstract

The invention relates to the technical field of high-entropy oxide and electrocatalyst synthesis, in particular to a double-phase hollow high-entropy oxide catalyst and a preparation method and application thereof, the double-phase hollow high-entropy oxide catalyst comprises metal elements and non-metal elements, the metal elements comprise ruthenium, nickel, cobalt, iron, manganese and chromium; the non-metallic element is oxygen; the chemical formula of the double-phase hollow high-entropy oxide catalyst is NiCoFeMnCrRuO. The invention further discloses a preparation method of the catalyst. The double-phase hollow high-entropy oxide catalyst has a multi-shell hollow structure, provides a larger specific surface area and exposes a large number of reaction active sites, so that the double-phase hollow high-entropy oxide catalyst has lower overpotential, higher reaction efficiency and good electrochemical stability; meanwhile, the preparation method of the double-phase hollow high-entropy oxide catalyst is simple in process, low in cost, high in repeatability and suitable for industrial mass production, and has a wide application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of high entropy oxides and electrocatalyst synthesis, and in particular to a two-phase hollow high entropy oxide catalyst, a preparation method and applications thereof. Background Art

[0002] Hydrogen, as an efficient and environmentally friendly energy carrier, has attracted increasing attention, and the hydrogen economy has been strongly advocated. To achieve decarbonization of the energy system, research on hydrogen production through water electrolysis is essential. The water electrolysis reaction involves the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). The sluggish kinetics of the OER, involving four fundamental steps and four electron transfers, severely limits the overall water splitting efficiency and hinders its further practical application. Developing efficient electrocatalysts is key to accelerating the reaction and thus reducing the electrolysis overpotential. To date, noble metal-based materials remain the most effective electrocatalysts, such as Pt for the HER and IrO2 and RuO2 for the OER. Despite their optimal catalytic performance, these noble metal electrocatalysts remain prohibitive for industrial applications due to their scarcity and high price. Given these key drawbacks, exploring alternative noble metal catalysts with low cost, good electrocatalytic performance, and sufficient durability is crucial to significantly improve water electrolysis performance.

[0003] High-entropy oxides (HEOs) are an emerging class of materials composed of five or more metal elements. Leveraging the synergistic effects of their multimetallic components, lattice distortion, and entropy stabilization, they exhibit exceptional structural stability and electrochemical performance, making them promising candidates for electrocatalysis, particularly in oxygen evolution reaction (OER). Their flexible composition and controllability offer ample scope for further optimizing their performance.

[0004] However, relying solely on a single high-entropy oxide is still not enough to fully meet the requirements of high activity and high stability. The introduction of more complex structures has become a new research direction, and constructing a dual-phase heterostructure is one of the effective strategies.

[0005] Therefore, it is of great significance to develop a dual-phase high-entropy oxide catalyst with low overpotential and fast reaction efficiency. Summary of the Invention The purpose of the present invention is to overcome the defects of slow reaction of traditional electrocatalysts and the inability of precious metal electrocatalysts to be used in industrial production due to their scarcity and high price, thereby providing a two-phase hollow high-entropy oxide catalyst and its preparation method and application. The two-phase hollow high-entropy oxide catalyst has a multi-shell hollow structure, which provides a larger specific surface area, thereby exposing a large number of reaction active sites, so that the two-phase hollow high-entropy oxide catalyst has a lower overpotential, faster reaction efficiency and good electrochemical stability. At the same time, the preparation method of the two-phase hollow high-entropy oxide catalyst is simple in process, low in cost, and highly repeatable, is suitable for industrial mass production, and has broad application prospects.

[0006] In order to achieve the above objectives, in a first aspect, the present invention provides a dual-phase hollow high-entropy oxide catalyst, wherein the dual-phase hollow high-entropy oxide catalyst comprises a metal element and a non-metal element, wherein: The metal elements include ruthenium, nickel, cobalt, iron, manganese and chromium; The non-metallic element is oxygen; The chemical formula of the dual-phase hollow high entropy oxide catalyst is NiCoFeMnCrRuO.

[0007] Preferably, the particle size of the dual-phase hollow high entropy oxide catalyst is 0.8 μm to 3.5 μm.

[0008] Preferably, the biphasic hollow high entropy oxide catalyst has a fluorite-type / corundum-type biphasic heterogeneous structure.

[0009] Preferably, the biphasic hollow high entropy oxide catalyst has a multi-shell hollow spherical structure.

[0010] Preferably, the number of the shell layers is 1 to 3.

[0011] Preferably, the shell layer has a thickness of 100 nm to 500 nm.

[0012] In a second aspect, the present invention provides a method for preparing a biphasic hollow high entropy oxide catalyst, the preparation method comprising: 1) In the presence of a solvent, a complexing agent and a metal salt are mixed to obtain a mixed solution; 2) subjecting the mixed solution of step 1) to a hydrothermal reaction to obtain precursor microspheres; 3) calcining the precursor microspheres in step 2) to obtain a dual-phase hollow high entropy oxide catalyst.

[0013] Preferably, in step 1), the solvent is water.

[0014] Preferably, the complexing agent is one or two or more of glucose, citric acid and xylitol.

[0015] Preferably, the metal salts are five metal salts selected from the group consisting of ruthenium salts, nickel salts, cobalt salts, iron salts, manganese salts and chromium salts.

[0016] Preferably, the ruthenium salt is ruthenium trichloride and / or ruthenium nitrate.

[0017] Preferably, the nickel salt is selected from one or two or more of nickel chloride, nickel nitrate, nickel sulfate and nickel acetate.

[0018] Preferably, the cobalt salt is selected from one or two or more of cobalt chloride, cobalt nitrate and cobalt sulfate.

[0019] Preferably, the iron salt is selected from one or two or more of ferric chloride, ferric nitrate and ferric sulfate.

[0020] Preferably, the manganese salt is selected from one or two or more of manganese chloride, manganese nitrate, manganese sulfate and manganese acetate.

[0021] Preferably, the chromium salt is selected from one or two or more of chromium chloride, chromium nitrate and chromium sulfate.

[0022] Preferably, in step 1), the concentration of the complexing agent is 15 g / L to 135 g / L.

[0023] Preferably, in step 1), the molar concentration of the ruthenium salt is 5 mmol / L to 55 mmol / L, wherein the ruthenium salt is calculated as ruthenium element.

[0024] Preferably, in step 1), the molar concentrations of the nickel salt, cobalt salt, iron salt, manganese salt and chromium salt are all 5 mmol / L to 70 mmol / L, wherein the nickel salt is calculated as nickel element, the cobalt salt is calculated as cobalt element, the iron salt is calculated as iron element, the manganese salt is calculated as manganese element, and the chromium salt is calculated as chromium element.

[0025] Preferably, in step 2), the conditions of the hydrothermal reaction include: temperature of 120° C. to 220° C., and time of 1 h to 12 h.

[0026] Preferably, in step 2), the particle size of the precursor microspheres is 1 μm to 4 μm.

[0027] Preferably, in step 3), the calcination conditions include: temperature of 300°C to 900°C, time of 1 h to 5 h, and heating rate of 1°C / min to 7°C / min.

[0028] In the third aspect, the present invention provides a biphasic hollow high entropy oxide catalyst prepared by the preparation method according to the second aspect, wherein the biphasic hollow high entropy oxide catalyst has a high entropy at 10 mA / cm 2Under these conditions, the potential for oxygen evolution is 180 mV~290 mV, and the potential for hydrogen evolution is 80 mV~180 mV.

[0029] In a fourth aspect, the present invention provides an application of the biphasic hollow high entropy oxide catalyst as described in the first aspect or the biphasic hollow high entropy oxide catalyst as described in the third aspect in the field of water electrolysis.

[0030] In the above technical solution, the present invention utilizes a hydrothermal reaction combined with a calcination strategy to prepare a dual-phase heterojunction multi-shell hollow high-entropy oxide catalyst. First, during the hydrothermal reaction, a complexing agent containing a large number of hydroxyl groups is used to complex with metal ions, thereby forming amorphous carbon spheres coated with multiple metal ions. Then, by regulating the high-temperature calcination temperature and heating rate, the diffusion rate of different metal ions is controlled, 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 high-entropy oxide. Further, by regulating the content of the ruthenium precursor, the high-entropy oxide can achieve the evolution process 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. The dual-phase heterostructure can effectively promote the rapid conversion of intermediates and accelerate the reaction kinetics. At the same time, the introduction of the high-entropy strategy can effectively improve the stability of the electrocatalytic reaction, showing excellent electrocatalytic oxygen evolution reaction (OER) and electrocatalytic hydrogen evolution reaction (HER) performance.

[0031] At the same time, the preparation method of the dual-phase hollow high-entropy oxide catalyst of the present invention has simple process, low cost, strong repeatability, is suitable for industrial mass production, and has broad application prospects.

[0032] Moreover, the dual-phase hollow high-entropy oxide catalyst of the present invention has a fluorite-type / corundum-type crystal phase and a multi-shell, hollow spherical morphology. With the synergistic effect of its multi-metal components, lattice distortion effect, and entropy stabilization characteristics, it exhibits excellent structural stability and electrochemical performance. Through element design, the composition and phase structure of the high-entropy oxide can be regulated to enhance its catalytic performance. On this basis, the design of a multi-shell hollow microsphere structure is adopted to increase the specific surface area and reaction active sites, thereby enhancing the electrocatalytic reaction activity.

[0033] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the following detailed description, they are used to explain the present invention but do not constitute a limitation of the present invention. In the accompanying drawings: Figure 1 is a SEM photograph of the high entropy oxide precursor prepared in Example 5, wherein: Figure 1 (a) is at a magnification of 7000 times. Figure 1 (b) The magnification is 15,000 times; Figure 2 is a SEM photograph of the dual-phase hollow high entropy oxide catalyst prepared in Example 5; wherein, Figure 2 (a) is at a magnification of 6000 times. Figure 2 (b) The magnification is 35,000 times; Figure 3 is the XRD spectrum of the dual-phase hollow high entropy oxide catalyst in Example 5; Figure 4 The results of the structure and elemental analysis of the dual-phase hollow high entropy oxide catalyst prepared in Example 5 are as follows; wherein, Figure 4 (a) is a TEM image of the dual-phase hollow high entropy oxide catalyst prepared in Example 5, Figure 4 (b) is a HRTEM image of the dual-phase hollow high entropy oxide catalyst prepared in Example 5. Figure 4 (c) HADDF and EDS element distribution photos of the dual-phase hollow high entropy oxide catalyst prepared in Example 5; Figure 5 The results of hydrogen evolution and oxygen absorption performance tests on the two-phase hollow high entropy oxide catalysts prepared in Examples 5-6 and the catalysts prepared in Comparative Examples 1-2 are shown; wherein, Figure 5 (a) LSV curves of the OER of the dual-phase hollow high entropy oxide catalyst prepared in Examples 5-6 and the catalyst prepared in Comparative Examples 1-2 in 1 M KOH solution; Figure 5 (b) is the LSV curve of HER of the dual-phase hollow high entropy oxide catalyst prepared in Example 5-6 and the catalyst prepared in Comparative Example 1-2 in 1 M KOH solution. DETAILED DESCRIPTION

[0035] The following is a detailed description of the specific embodiments of the present invention. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.

[0036] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0037] In a first aspect, the present invention provides a dual-phase hollow high-entropy oxide catalyst, wherein the dual-phase hollow high-entropy oxide catalyst comprises a metal element and a non-metal element, wherein: The metal elements include ruthenium, nickel, cobalt, iron, manganese and chromium; The non-metallic element is oxygen; The chemical formula of the dual-phase hollow high entropy oxide catalyst is NiCoFeMnCrRuO.

[0038] The present invention utilizes a hydrothermal reaction combined with a calcination strategy to prepare a dual-phase heterojunction multi-shell hollow high-entropy oxide catalyst. First, during the hydrothermal reaction, a complexing agent containing a large number of hydroxyl groups is used to complex with metal ions, thereby forming amorphous carbon spheres coated with multiple metal ions. The diffusion rate of different metal ions is then controlled by regulating the high-temperature 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 number of active sites of the high-entropy oxide. Furthermore, by regulating the content of the ruthenium precursor, the high-entropy oxide evolves 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. The dual-phase heterostructure can effectively promote the rapid conversion of intermediates and accelerate reaction kinetics. At the same time, the introduction of the high-entropy strategy can effectively improve the stability of the electrocatalytic reaction, exhibiting excellent electrocatalytic oxygen evolution reaction (OER) and electrocatalytic hydrogen evolution reaction (HER) performance.

[0039] In a preferred embodiment of the present invention, the particle size of the dual-phase hollow high entropy oxide catalyst is 0.8 μm to 3.5 μm.

[0040] In a preferred embodiment of the present invention, the dual-phase hollow high-entropy oxide catalyst has a fluorite-type / corundum-type dual-phase heterogeneous structure.

[0041] In a preferred embodiment of the present invention, the dual-phase hollow high entropy oxide catalyst has a multi-shell hollow spherical structure.

[0042] In a preferred embodiment of the present invention, the number of the shell layers is 1 to 3 layers, and can be 1 layer, 2 layers or 3 layers.

[0043] In a preferred embodiment of the present invention, the shell layer thickness is 100 nm to 500 nm.

[0044] In a second aspect, the present invention provides a method for preparing a biphasic hollow high entropy oxide catalyst, the preparation method comprising: 1) In the presence of a solvent, a complexing agent and a metal salt are mixed to obtain a mixed solution; 2) subjecting the mixed solution of step 1) to a hydrothermal reaction to obtain precursor microspheres; 3) calcining the precursor microspheres in step 2) to obtain a dual-phase hollow high entropy oxide catalyst.

[0045] The preparation method of the dual-phase hollow high-entropy oxide catalyst of the present invention has simple process, low cost, strong repeatability, is suitable for industrial mass production, and has broad application prospects.

[0046] In a preferred embodiment of the present invention, in step 1), the solvent is water, which can be deionized water, ultrapure water or distilled water.

[0047] In a preferred embodiment of the present invention, in order to ensure that the metal ions are uniformly dispersed during the hydrothermal process and form a stable precursor, and at the same time construct a multi-shell hollow structure through the carbonization process to increase the specific surface area and active sites, in step 1), the complexing agent is one or two or more of glucose, citric acid and xylitol, preferably glucose. These complexing agents all contain multiple hydroxyl or carboxyl groups and have metal complexing capabilities. They are complexed with metal ions through their hydroxyl groups to form precursor microspheres, and a multi-shell hollow structure is formed after calcination.

[0048] In a preferred embodiment of the present invention, in order to construct a high entropy oxide system through the synergistic effect of multiple metal components, in step 1), the metal salt is ruthenium salt, nickel salt, cobalt salt, iron salt, manganese salt and chromium salt.

[0049] In a preferred embodiment of the present invention, in step 1), the ruthenium salt is ruthenium trichloride and / or ruthenium nitrate, for example, ruthenium trichloride, ruthenium nitrate or a mixture of ruthenium trichloride and ruthenium nitrate.

[0050] In a preferred embodiment of the present invention, in step 1), the nickel salt is selected from one or two or more of nickel chloride, nickel nitrate, nickel sulfate and nickel acetate, for example, nickel chloride, nickel nitrate, nickel sulfate, nickel acetate, a mixture of nickel chloride and nickel nitrate, a mixture of nickel chloride and nickel sulfate, a mixture of nickel chloride and nickel acetate, or a mixture of nickel nitrate and nickel sulfate.

[0051] In a preferred embodiment of the present invention, in step 1), the cobalt salt is selected from one or two or more of cobalt chloride, cobalt nitrate and cobalt sulfate, for example, it can be cobalt chloride, cobalt nitrate, cobalt sulfate, a mixture of cobalt chloride and cobalt nitrate, a mixture of cobalt chloride and cobalt sulfate, or a mixture of cobalt nitrate and cobalt sulfate.

[0052] In a preferred embodiment of the present invention, in step 1), the iron salt is selected from one or two or more of ferric chloride, ferric nitrate and ferric sulfate, for example, it can be ferric chloride, ferric nitrate, ferric sulfate, a mixture of ferric chloride and ferric nitrate, a mixture of ferric chloride and ferric sulfate, or a mixture of ferric nitrate and ferric sulfate.

[0053] In a preferred embodiment of the present invention, in step 1), the manganese salt is selected from one or two or more of manganese chloride, manganese nitrate, manganese sulfate and manganese acetate, for example, it can be manganese chloride, manganese nitrate, manganese sulfate, manganese acetate, a mixture of manganese chloride and manganese nitrate, a mixture of manganese chloride and manganese sulfate, a mixture of manganese chloride and manganese acetate, or a mixture of manganese nitrate and manganese sulfate.

[0054] In a preferred embodiment of the present invention, in step 1), the chromium salt is selected from one or two or more of chromium chloride, chromium nitrate and chromium sulfate, for example, it can be chromium chloride, chromium nitrate, chromium sulfate, a mixture of chromium chloride and chromium nitrate, a mixture of chromium chloride and chromium sulfate, or a mixture of chromium nitrate and chromium sulfate.

[0055] In a preferred embodiment of the present invention, in step 1), the concentration of the complexing agent is 15 g / L-135 g / L, for example, it can be 15 g / L, 40 g / L, 45 g / L, 50 g / L, 55 g / L, 60 g / L, 65 g / L, 70 g / L, 80 g / L, 90 g / L, 100 g / L, 110 g / L, 120 g / L or 130 g / L.

[0056] In a preferred embodiment of the present invention, in step 1), the molar concentration of the ruthenium salt is 5 mmol / L to 55 mmol / L, wherein the ruthenium salt is calculated as ruthenium element, for example, 5 mmol / L, 10 mmol / L, 15 mmol / L, 20 mmol / L, 25 mmol / L, 30 mmol / L, 40 mmol / L, 50 mmol / L or 55 mmol / L.

[0057] In a preferred embodiment of the present invention, in step 1), the molar concentrations of the nickel salt, cobalt salt, iron salt, manganese salt and chromium salt are all 5 mmol / L to 70 mmol / L, wherein the nickel salt is calculated as nickel element, the cobalt salt is calculated as cobalt element, the iron salt is calculated as iron element, the manganese salt is calculated as manganese element, and the chromium salt is calculated as chromium element, for example, 5 mmol / L, 10 mmol / L, 20 mmol / L, 30 mmol / L, 35 mmol / L, 40 mmol / L, 50 mmol / L or 70 mmol / L.

[0058] In a preferred embodiment of the present invention, in step 2), the conditions of the hydrothermal reaction include: temperature of 120°C to 220°C, and time of 1 h to 12 h, for example, the temperature can be 120°C, and the time can be 1 h; the temperature can be 130°C, and the time can be 2 h; the temperature can be 150°C, and the time can be 3 h; the temperature can be 160°C, and the time can be 5 h; the temperature can be 170°C, and the time can be 6 h; the temperature can be 180°C, and the time can be 8 h; or the temperature can be 220°C, and the time can be 12 h.

[0059] In a preferred embodiment of the present invention, in step 2), the particle size of the precursor microspheres is 1 μm to 4 μm.

[0060] In a preferred embodiment of the present invention, in step 2), after the hydrothermal reaction, the product is cooled to room temperature, filtered, washed, and dried.

[0061] In a preferred embodiment of the present invention, the drying conditions include: drying in an oven at 30° C. to 60° C. for 1 h to 10 h.

[0062] In a preferred embodiment of the present invention, in step 3), the calcination conditions include: temperature of 300°C to 900°C, time of 1 h to 5 h, and heating rate of 1°C / min to 7°C / min.

[0063] In the third aspect, the present invention provides a biphasic hollow high entropy oxide catalyst prepared by the preparation method according to the second aspect, wherein the biphasic hollow high entropy oxide catalyst has a kinetic energy of 10 mA / cm in 1 M KOH. 2 Under these conditions, the potential for oxygen evolution is 180 mV~290 mV, and the potential for hydrogen evolution is 80 mV~180 mV.

[0064] In a fourth aspect, the present invention provides an application of the biphasic hollow high entropy oxide catalyst as described in the first aspect or the biphasic hollow high entropy oxide catalyst as described in the third aspect in the field of water electrolysis.

[0065] The dual-phase hollow high-entropy oxide catalyst of the present invention has a fluorite / corundum crystal phase and a multi-shell, hollow spherical morphology. Leveraging the synergistic effects of its multi-metal components, lattice distortion, and entropy stabilization properties, it exhibits excellent structural stability and electrochemical performance. Through elemental design, the composition and phase structure of the high-entropy oxide can be regulated to enhance its catalytic performance. Furthermore, the multi-shell hollow microsphere structure is designed to increase the specific surface area and reactive sites, thereby enhancing electrocatalytic reaction activity.

[0066] In the present invention, the room temperature is 15°C to 30°C.

[0067] The present invention will be described in detail below by way of examples. In the following examples, the drugs and pharmaceuticals are all conventional commercial products.

[0068] Example 1 1.0 g of anhydrous glucose was dispersed in 30 mL of deionized water and stirred for 10 min to obtain a glucose solution. Equimolar (0.4 mmol) of nickel chloride hexahydrate (NiCl2·6H2O), cobalt chloride hexahydrate (CoCl2·6H2O), ferric chloride hexahydrate (FeCl3·6H2O), manganese chloride tetrahydrate (MnCl2·4H2O), chromium chloride hexahydrate (CrCl3·6H2O) and 0.4 mmol of ruthenium chloride (RuCl3) were added to the glucose solution. After mixing evenly, the mixture was transferred to a 100 mL polytetrafluoroethylene reactor, heated to 120 °C, reacted for 12 h, cooled to room temperature, filtered and washed, and dried in an oven at 30 °C for 10 h to obtain a high entropy oxide precursor. The high entropy oxide precursor was placed in a muffle furnace, heated to 300 °C at a heating rate of 1 °C / min, and calcined for 5 h. The resulting product was a dual-phase hollow high entropy oxide catalyst, recorded as F / C-HEO-1.

[0069] Example 2 1.5 g of anhydrous glucose was dispersed in 30 mL of deionized water and stirred for 10 min to obtain a glucose solution. Equimolar (0.8 mmol) of NiCl2·6H2O, CoCl2·6H2O, FeCl3·6H2O, MnCl2·4H2O, CrCl3·6H2O, and 0.7 mmol of RuCl3 were added to the glucose solution, mixed evenly, and transferred to a 100 mL polytetrafluoroethylene reactor. The reaction was heated to 140 °C for 10 h. After cooling to room temperature, the product was filtered and washed, and dried in an oven at 40 °C for 8 h to obtain a high-entropy oxide precursor. The high entropy oxide precursor was placed in a muffle furnace, heated to 400 °C at a heating rate of 2 °C / min, and calcined for 3 h. The resulting product was a dual-phase hollow high entropy oxide catalyst, recorded as F / C-HEO-2.

[0070] Example 3 1.8 g of anhydrous glucose was dispersed in 40 mL of deionized water and stirred for 10 min to obtain a glucose solution. Equimolar (1.2 mmol) of NiCl2·6H2O, CoCl2·6H2O, FeCl3·6H2O, MnCl2·4H2O, CrCl3·6H2O, and 1.1 mmol of RuCl3 were added to the glucose solution, mixed evenly, and transferred to a 100 mL polytetrafluoroethylene reactor. The reaction was heated to 160 °C and reacted for 6 h. After cooling to room temperature, the mixture was filtered and washed, and dried in an oven at 60 °C for 4 h to obtain a high-entropy oxide precursor. The high entropy oxide precursor was placed in a muffle furnace, heated to 600 °C at a heating rate of 3 °C / min, and calcined for 3 h. The resulting product was a dual-phase hollow high entropy oxide catalyst, recorded as F / C-HEO-3.

[0071] Example 4 3 g of anhydrous glucose was dispersed in 50 mL of deionized water and stirred for 10 min to obtain a glucose solution. Equimolar (1.6 mmol) of NiCl2·6H2O, CoCl2·6H2O, FeCl3·6H2O, MnCl2·4H2O, CrCl3·6H2O, and 1.3 mmol of RuCl3 were added to the glucose solution, mixed evenly, and transferred to a 100 mL polytetrafluoroethylene reactor. The reaction was heated to 180 °C and allowed to react for 4 h. After cooling to room temperature, the product was filtered and washed, and dried in an oven at 60 °C for 2 h to obtain a high-entropy oxide precursor. The high entropy oxide precursor was placed in a muffle furnace, heated to 700 °C at a heating rate of 5 °C / min, and calcined for 2 h. The resulting product was a dual-phase hollow high entropy oxide catalyst, recorded as F / C-HEO-4.

[0072] Example 5 4 g of anhydrous glucose was dispersed in 60 mL of deionized water and stirred for 10 min to obtain a glucose solution. Equimolar (2 mmol) of NiCl2·6H2O, CoCl2·6H2O, FeCl3·6H2O, MnCl2·4H2O, CrCl3·6H2O, and 1.4 mmol of RuCl3 were added to the glucose solution, mixed evenly, and transferred to a 100 mL polytetrafluoroethylene reactor. The reaction was heated to 220 °C for 1 h. After cooling to room temperature, the product was filtered and washed, and dried in an oven at 50 °C for 7 h to obtain a high-entropy oxide precursor. The high entropy oxide precursor was placed in a muffle furnace, heated to 900 °C at a heating rate of 7 °C / min, and calcined for 1 h. The resulting product was a dual-phase hollow high entropy oxide catalyst, recorded as F / C-HEO-5.

[0073] Depend on Figure 1 From the SEM image of the high entropy oxide precursor prepared in Example 5, it can be seen that the high entropy oxide precursor of the present invention has a spherical structure.

[0074] Depend on Figure 2 From the SEM image of the dual-phase hollow high-entropy oxide catalyst prepared in Example 5, it can be seen that the morphology and size of the dual-phase hollow high-entropy oxide catalyst prepared in Example 5 of the present invention are uniform, forming an obvious hollow structure, and its shell is dense.

[0075] Depend on Figure 3 From the XRD spectrum of the dual-phase hollow high-entropy oxide catalyst prepared in Example 5, it can be seen that the dual-phase hollow high-entropy oxide catalyst prepared in Example 5 of the present invention has a dual-phase heterogeneous structure of fluorite-type structure and corundum-type structure.

[0076] Depend on Figure 4 (a) TEM image of the dual-phase hollow high entropy oxide catalyst prepared in Example 5 and Figure 4 (b) HRTEM image of the dual-phase hollow high-entropy oxide catalyst prepared in Example 5. It can be seen that the dual-phase hollow high-entropy oxide catalyst prepared in Example 5 of the present invention has a uniform morphology and size, a hollow core-shell structure, and forms a fluorite / corundum dual-phase structure; Figure 4 (c) HADDF and EDS element distribution of the dual-phase hollow high-entropy oxide catalyst prepared in Example 5 It can be seen that the dual-phase hollow high-entropy oxide catalyst prepared in Example 5 of the present invention contains Fe, Co, Ni, Cr, Mn, Ru, C and O elements.

[0077] Example 6 1.8 g of anhydrous glucose was dispersed in 30 mL of deionized water and stirred for 10 min to obtain a glucose solution. Equimolar (1.65 mmol) of NiCl2·6H2O, CoCl2·6H2O, FeCl3·6H2O, MnCl2·4H2O, CrCl3·6H2O, and 1.2 mmol of RuCl3 were added to the glucose solution, mixed evenly, and 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 and washed, and dried in an oven at 60 °C for 3 h to obtain a high-entropy oxide precursor. The high entropy oxide precursor was placed in a muffle furnace, heated to 700 °C at a heating rate of 3 °C / min, and calcined for 3 h. The resulting product was a dual-phase hollow high entropy oxide catalyst, recorded as F / C-HEO-6.

[0078] Comparative Example 1 1.8 g of anhydrous glucose was dispersed in 30 mL of deionized water and stirred for 10 min to obtain a glucose solution. Equimolar (1.65 mmol) of NiCl2·6H2O, CoCl2·6H2O, FeCl3·6H2O, MnCl2·4H2O, and CrCl3·6H2O were added to the glucose solution, mixed evenly, and transferred to a 100 mL polytetrafluoroethylene reactor. The reaction was heated to 160 °C for 12 h. After cooling to room temperature, the product was filtered and washed, and dried in an oven at 60 °C for 3 h to obtain a high entropy oxide precursor. The high entropy oxide precursor was placed in a muffle furnace, heated to 700 °C at a heating rate of 3 °C / min, and calcined for 3 h. The resulting product was a single-phase corundum-type multi-shell hollow high entropy oxide catalyst, denoted as C-HEO.

[0079] Comparative Example 2 1.8 g of anhydrous glucose was dispersed in 30 mL of deionized water and stirred for 10 min to obtain a glucose solution. Equimolar (1.65 mmol) of NiCl2·6H2O, CoCl2·6H2O, FeCl3·6H2O, MnCl2·4H2O, CrCl3·6H2O, and 1.6 mmol of RuCl3 were added to the glucose solution, mixed evenly, and transferred to a 100 mL polytetrafluoroethylene reactor. The reaction was heated to 160 °C for 12 h. After cooling to room temperature, the product was filtered and washed, and dried in an oven at 60 °C for 3 h to obtain a high-entropy oxide precursor. The high entropy oxide precursor was placed in a muffle furnace, heated to 700 °C at a heating rate of 3 °C / min, and calcined for 3 h. The resulting product was a single-phase fluorite-type multi-shell hollow high entropy oxide catalyst, denoted as F-HEO.

[0080] Table 1

[0081] Application Example 1 The biphasic hollow high entropy oxide catalysts prepared in Examples 1-6 and the catalysts prepared in Comparative Examples 1-2 were ground for 1 h, and 10 mg of each was mixed with 1 mL of a mixed solution of water and isopropanol (the volume ratio of water to isopropanol was 3:1) and 50 μL of a Nafion solution and ultrasonically dispersed for 30 min to obtain a dispersion. Then, 10 μL of the above dispersion was applied to the working electrode, and the electrode was dried at room temperature. A 1 M KOH solution was used as the electrolyte, a stone mill rod was used as the counter electrode, and Ag / AgCl was used as the reference electrode to form a three-electrode system with the above working electrode, and its water electrolysis performance was tested.

[0082] Test Example 1 The two-phase hollow high entropy oxide catalysts prepared in Examples 1-6 and the catalysts prepared in Comparative Examples 1-2 in Application Example 1 were used as electrolytic water catalysts. The three-electrode system was subjected to a 1 M KOH solution at 10 mA·cm -2 Under the current density, the oxygen evolution potential (OER) and hydrogen evolution potential (HER) were measured. The results are shown in Table 2 and Figure 5 shown.

[0083] Table 2

[0084] In the table, “—” indicates that the catalyst cannot reach 10 mA / cm in 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.

[0085] Combined with the data in Table 2 Figure 5 It can be found from the content that the biphasic hollow high entropy oxide catalyst prepared in Example 5 has excellent electrolytic water performance due to its hollow structure and biphasic structure. -2 At a current density of 1.5 Å, the OER overpotential was 275 mV, and the HER overpotential was 138 mV. However, the OER and HER performances of Examples 1-4 and 6 were inferior to those of Example 5. This was because the amount of ruthenium salt used in the two-phase hollow high-entropy oxide catalysts prepared in Examples 1-4 and 6 was lower than that in Example 5, and the hydrothermal and calcination process parameters deviated from the optimal values, resulting in an incomplete hollow shell structure and a reduced two-phase interface area, which affected their performance.

[0086] The catalyst prepared in Comparative Example 1 lacks ruthenium, resulting in insufficient OER / HER active sites and slow reaction kinetics. In addition, the pure metal oxide has weak conductivity and low electron transfer efficiency, which cannot reach 10 mA·cm -2 The current density requires a higher overpotential to drive the reaction, as explained in Comparative Example 1.

[0087] The catalyst prepared in Comparative Example 2 is completely converted into the fluorite phase due to the excessive incorporation of ruthenium, and loses the stability support of the corundum phase, which easily causes structural collapse during the cycle, resulting in poor catalytic activity.

[0088] In summary, the present invention utilizes a hydrothermal reaction combined with a calcination strategy to prepare a dual-phase heterojunction multi-shell hollow high-entropy oxide catalyst. First, during the hydrothermal reaction, a complexing agent containing a large number of hydroxyl groups is used to complex with metal ions to form amorphous carbon spheres coated with a variety of metal ions; then, the diffusion rate of different metal ions is controlled by regulating the high-temperature calcination temperature and heating rate, 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 high-entropy oxide, providing a new path for improving the performance of the dual-phase high-entropy oxide, achieving low overpotential, fast reaction efficiency and excellent electrochemical stability.

[0089] By further controlling the ratio and composition of different metal ions, the phase structure of the dual-phase high-entropy oxide can be controlled, thereby broadening its application areas. By regulating the content of ruthenium precursor, the evolution process of the high-entropy oxide 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 can be achieved. The dual-phase heterostructure can combine the advantages of different components and optimize the electronic structure of the active site through the interfacial synergistic effect, thereby enhancing the adsorption capacity of the reaction intermediates and significantly improving the catalytic performance.

[0090] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the scope of protection of the present invention.

[0091] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0092] In addition, the various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A two-phase hollow high entropy oxide catalyst, characterized in that: The dual-phase hollow high entropy oxide catalyst comprises metal elements and non-metal elements, wherein: The metal elements include ruthenium, nickel, cobalt, iron, manganese and chromium; The non-metallic element is oxygen; The chemical formula of the dual-phase hollow high entropy oxide catalyst is NiCoFeMnCrRuO.

2. The dual-phase hollow high entropy oxide catalyst according to claim 1, characterized in that The particle size of the dual-phase hollow high-entropy oxide catalyst is 0.8 μm to 3.5 μm.

3. The dual-phase hollow high entropy oxide catalyst according to claim 1 or 2, characterized in that: The dual-phase hollow high-entropy oxide catalyst has a fluorite-type / corundum-type dual-phase heterogeneous structure; and / or, The dual-phase hollow high entropy oxide catalyst has a multi-shell hollow spherical structure; and / or, The number of the shell layers is 1 to 3; and / or, The shell layer thickness is 100 nm to 500 nm.

4. A method for preparing a dual-phase hollow high entropy oxide catalyst, characterized in that: The preparation method comprises: 1) In the presence of a solvent, a complexing agent and a metal salt are mixed to obtain a mixed solution; 2) subjecting the mixed solution of step 1) to a hydrothermal reaction to obtain precursor microspheres; 3) calcining the precursor microspheres in step 2) to obtain a dual-phase hollow high entropy oxide catalyst.

5. The preparation method according to claim 4, characterized in that In step 1), the solvent is water; and / or, The complexing agent is glucose, citric acid and xylitol; and / or, The metal salt is a ruthenium salt, a nickel salt, a cobalt salt, an iron salt, a manganese salt and a chromium salt; and / or, The ruthenium salt is ruthenium trichloride and / or ruthenium nitrate; and / or, The nickel salt is selected from one or two or more of nickel chloride, nickel nitrate, nickel sulfate and nickel acetate; and / or, The cobalt salt is selected from one or two or more of cobalt chloride, cobalt nitrate and cobalt sulfate; and / or, The iron salt is selected from one or two or more of ferric chloride, ferric nitrate and ferric sulfate; and / or, The manganese salt is selected from one or two or more of manganese chloride, manganese nitrate, manganese sulfate and manganese acetate; and / or, The chromium salt is selected from one or two or more of chromium chloride, chromium nitrate and chromium sulfate.

6. The preparation method according to claim 4 or 5, characterized in that In step 1), the concentration of the complexing agent is 15 g / L to 135 g / L; and / or, The molar concentration of the ruthenium salt is 5 mmol / L to 55 mmol / L, wherein the ruthenium salt is calculated as ruthenium element; and / or, The molar concentrations of the nickel salt, cobalt salt, iron salt, manganese salt and chromium salt are all 5 mmol / L to 70 mmol / L, wherein the nickel salt is calculated as nickel element, the cobalt salt is calculated as cobalt element, the iron salt is calculated as iron element, the manganese salt is calculated as manganese element, and the chromium salt is calculated as chromium element.

7. The preparation method according to claim 4, characterized in that In step 2), the conditions of the hydrothermal reaction include: temperature of 120°C to 220°C, time of 1 h to 12 h; and / or, The particle size of the precursor microspheres is 1 μm to 4 μm.

8. The preparation method according to claim 4, characterized in that In step 3), the calcination conditions include: temperature of 300°C to 900°C, time of 1 h to 5 h, and heating rate of 1°C / min to 7°C / min.

9. A dual-phase hollow high entropy oxide catalyst prepared by the preparation method according to any one of claims 4 to 8, characterized in that: The dual-phase hollow high entropy oxide catalyst has a high conductivity at 10 mA / cm 2 Under these conditions, the potential for oxygen evolution is 180 mV~290 mV, and the potential for hydrogen evolution is 80 mV~180 mV.

10. Use of the biphasic hollow high entropy oxide catalyst according to any one of claims 1 to 3 or the biphasic hollow high entropy oxide catalyst according to claim 9 in the field of water electrolysis.

Images