An aluminum and phosphorus co-doped heterostructure cobaltosic oxide / nickel ferrite / foam nickel composite nanomaterial, a preparation method and application thereof

Abstract

The application relates to the field of material preparation, and relates to an aluminum and phosphorus co-doped heterostructure cobalt trioxide / iron nickel oxide / foam nickel composite nanomaterial and a preparation method and application thereof. The aluminum and phosphorus co-doped heterostructure cobalt trioxide / iron nickel oxide / foam nickel composite nanomaterial has a heterostructure of two-dimensional nanosheet layers grown on nanowires, is beneficial to mass and charge transmission, changes the electronic structure of Co3O4 and NiFe2O4 through aluminum and phosphorus co-doping, further improves the electrocatalytic performance, meanwhile, the aluminum and phosphorus co-doped heterostructure cobalt trioxide / iron nickel oxide / foam nickel composite nanomaterial preparation method adopts simple raw materials and process equipment, is low in cost, is beneficial to large-scale production, is expected to produce good social and economic effects, and has good catalytic electrolytic water oxygen evolution reaction activity in an alkaline environment.

Description

Technical Field

[0001] This invention relates to the field of materials preparation, specifically to an aluminum-phosphorus co-doped heterostructure cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterial, its preparation method, and its application. Background Technology

[0002] With the increasing severity of environmental pollution and energy shortages caused by the massive consumption of fossil fuels, the importance and urgency of developing and utilizing new energy sources have become a broad consensus in the international community. Many studies are dedicated to developing clean, sustainable, and renewable energy. Among these, electrochemical water splitting into hydrogen and oxygen is an eco-friendly and economically feasible large-scale hydrogen production scheme. Generally, the overall water electrolysis process includes the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). However, compared to the two-electron transfer HER, the oxygen evolution reaction (OER), involving the kinetics of four-electron proton coupling transfer, is slower and is considered the rate-determining step in water splitting. The high overpotential of the OER leads to significant energy loss, hindering the large-scale production of hydrogen. To improve the catalytic efficiency of electrocatalytic water splitting, designing highly active, low-cost, and stable OER catalysts is extremely important.

[0003] Currently, noble metal catalysts such as RuO2 and IrO2 exhibit high catalytic activity for OER under alkaline conditions, but their high price, extreme scarcity, and poor durability make them unsuitable for meeting the enormous demand for large-scale hydrogen production in the future. Studies have shown that non-noble metal compounds often exhibit superior catalytic stability and durability compared to carbon-based materials in harsh electrolysis environments. Three-dimensional transition metal compounds, especially spinel materials, have attracted widespread attention due to their advantages such as good stability, abundant reserves, low cost, ease of synthesis, and structural diversity. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of precious metal catalysts, such as high price, extreme scarcity, and poor durability, which make them difficult to mass-produce. This invention provides an aluminum-phosphorus co-doped heterostructured cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterial, its preparation method, and its applications. This aluminum-phosphorus co-doped heterostructured cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterial has a heterostructure with two-dimensional nanosheets grown on nanowires, which is beneficial for mass and charge transfer. The co-doping of aluminum and phosphorus alters the electronic structure of Co3O4 and NiFe2O4, further improving its electrocatalytic performance. Furthermore, the preparation method of this aluminum-phosphorus co-doped heterostructured cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterial uses simple raw materials and low-cost equipment, which is conducive to large-scale production and is expected to generate good social and economic benefits. It also exhibits good catalytic activity in the oxygen evolution reaction of water electrolysis under alkaline conditions.

[0005] To achieve the above objectives, in a first aspect, the present invention provides an aluminum-phosphorus co-doped heterostructured cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterial, wherein the chemical formula of the aluminum-phosphorus co-doped heterostructured cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterial is AP-Co3O4@NiFe2O4 / NF, wherein...

[0006] The structure of the aluminum and phosphorus co-doped heterostructure cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterial is a heterostructure in which two-dimensional nanosheets are grown on nanowires.

[0007] Secondly, this invention provides a method for preparing aluminum and phosphorus co-doped heterostructured cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterials, wherein the preparation method is as follows:

[0008] 1) Preparation of aluminum-doped cobalt tetroxide / nickel foam composite nanomaterials: In the presence of a first solvent, cobalt salt, aluminum salt and alkaline substance are first mixed, and then pretreated nickel foam is added to carry out a first hydrothermal reaction and calcined to obtain aluminum-doped cobalt tetroxide / nickel foam composite nanomaterials.

[0009] 2) Preparation of aluminum and phosphorus co-doped cobalt tetroxide / nickel foam composite nanomaterials: Under an inert atmosphere, the aluminum-doped cobalt tetroxide / nickel foam composite nanomaterials described in step 1) are phosphated with a phosphorus source to obtain aluminum and phosphorus co-doped cobalt tetroxide / nickel foam composite nanomaterials.

[0010] 3) Preparation of aluminum and phosphorus co-doped heterostructure cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterials: In the presence of a second solvent, nickel salt, iron salt and reducing agent are mixed and added to the aluminum and phosphorus co-doped cobalt tetroxide / nickel foam composite nanomaterials described in step 2) for a second hydrothermal reaction.

[0011] Thirdly, the present invention provides an aluminum-phosphorus co-doped heterostructured cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterial prepared by the method described in the second aspect.

[0012] Fourthly, the present invention provides the application of the aluminum and phosphorus co-doped heterostructured cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterial described in the first or third aspect as an electrocatalyst in the catalytic electrolysis of water for oxygen evolution reaction.

[0013] Through the above technical solution, the linear Co3O4 in the aluminum-phosphorus co-doped heterostructured cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterial (AP-Co3O4@NiFe2O4 / NF) of this invention is covered by NiFe2O4 sheets, forming a rich heterostructure that is beneficial for mass and charge transfer. The co-doping of Al and P elements in Co3O4@NiFe2O4 / NF increases oxygen vacancies, promotes charge transfer, and achieves an optimal balance of surface chemical states. These improvements significantly enhance the intrinsic activity of the Co3O4@NiFe2O4 / NF catalyst. Furthermore, the synergistic effect of oxygen vacancies and the AP-Co3O4@NiFe2O4 / NF heterostructure improves the conductivity of the electrocatalyst and provides more active sites for OER participation.

[0014] Meanwhile, the preparation method of the aluminum-phosphorus co-doped heterostructured cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterial of the present invention firstly grows Al-Co3O4 / NF on a three-dimensional NF conductive framework using a simple hydrothermal method and low-temperature calcination method, then obtains AP-Co3O4 / NF through a low-temperature gas-phase phosphating method, and finally obtains oxygen-vacancy-rich AP-Co3O4@NiFe2O4 / NF heterostructured composite nanomaterial by using a secondary mild hydrothermal method to mix nickel salt, iron salt, and reducing agent in a solvent. The present invention, by designing a suitable liquid-phase reaction system, facilitates ion diffusion and gaseous product release, providing a rapid electron channel for electrocatalysis. It has the advantages of simple operation, economical and environmentally friendly reagents, low cost, ease of operation, and suitability for mass production.

[0015] The aluminum and phosphorus co-doped heterostructured cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterial of the present invention can be used as an electrocatalyst for the oxygen evolution reaction. The heterostructured aluminum and phosphorus co-doped cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterial can be used to catalyze the oxygen evolution reaction under alkaline conditions. It has good electrocatalytic oxygen evolution reaction activity, which is conducive to large-scale utilization and promotion.

[0016] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0017] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the following detailed description to explain the invention, but do not constitute a limitation thereof. In the drawings:

[0018] Figure 1 The X-ray powder diffraction pattern of the aluminum-doped cobalt tetroxide / nickel foam composite nanomaterial obtained in step (1) of Example 1 is shown.

[0019] Figure 2The image shows a scanning electron microscope (SEM) image of the aluminum-doped cobalt tetroxide / nickel foam composite nanomaterial obtained in step (1) of Example 1.

[0020] Figure 3 The image shows a scanning electron microscope (SEM) image of the aluminum and phosphorus co-doped cobalt tetroxide / nickel foam composite nanomaterial obtained in step (2) of Example 1.

[0021] Figure 4 The X-ray powder diffraction pattern of the aluminum and phosphorus co-doped heterostructure cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterial of Example 1 is shown below.

[0022] Figure 5 The image shows a scanning electron microscope (SEM) image of the aluminum-phosphorus co-doped heterostructured cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterial from Example 1.

[0023] Figure 6 The image shows a transmission electron microscope (TEM) image of the aluminum and phosphorus co-doped heterostructured cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterial of Example 1.

[0024] Figure 7 The image shows a scanning electron microscope (SEM) image of the aluminum and phosphorus co-doped heterostructured cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterial of Example 2.

[0025] Figure 8 The image shows a scanning electron microscope (SEM) image of the aluminum and phosphorus co-doped heterostructured cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterial of Example 3.

[0026] Figure 9 The image shows a scanning electron microscope (SEM) image of the aluminum and phosphorus co-doped heterostructured cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterial of Example 4.

[0027] Figure 10 The image shows a scanning electron microscope (SEM) image of the aluminum-phosphorus co-doped heterostructured cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterial of Example 5.

[0028] Figure 11 The image shows a scanning electron microscope (SEM) image of the composite nanomaterial in Comparative Example 1.

[0029] Figure 12 Here is a scanning electron microscope image of the composite nanomaterial in Comparative Example 2;

[0030] Figure 13 The X-ray powder diffraction pattern of the cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterial of Comparative Example 3 is shown.

[0031] Figure 14 The image shows a scanning electron microscope image of the nickel ferrite / nickel foam composite nanomaterial in Comparative Example 4.

[0032] Figure 15The polarization curves of the AP-Co3O4@NiFe2O4 / NF composite nanomaterials obtained in Example 1, the Co3O4@NiFe2O4 / NF composite nanomaterials obtained in Comparative Example 3, and the NiFe2O4 / NF composite nanomaterials obtained in Comparative Example 4 in 1 mol / L KOH solution for catalytic oxygen evolution reaction are shown. Detailed Implementation

[0033] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0034] In a first aspect, the present invention provides an aluminum-phosphorus co-doped heterostructured cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterial, wherein the chemical formula of the aluminum-phosphorus co-doped heterostructured cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterial is AP-Co3O4@NiFe2O4 / NF, wherein...

[0035] The structure of the aluminum and phosphorus co-doped heterostructure cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterial is a heterostructure in which two-dimensional nanosheets are grown on nanowires.

[0036] In the aluminum-phosphorus co-doped heterostructured cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterial (AP-Co3O4@NiFe2O4 / NF) of this invention, linear Co3O4 is covered by NiFe2O4 sheets, forming a rich heterostructure that facilitates mass and charge transfer. The co-doping of Al and P elements in Co3O4@NiFe2O4 / NF increases oxygen vacancies, promotes charge transfer, and achieves an optimal balance of surface chemical states. These improvements significantly enhance the intrinsic activity of the Co3O4@NiFe2O4 / NF catalyst. Furthermore, the synergistic effect of oxygen vacancies and the AP-Co3O4@NiFe2O4 / NF heterostructure improves the conductivity of the electrocatalyst and provides more active sites for OER participation.

[0037] In a preferred embodiment of the present invention, the thickness of the aluminum and phosphorus co-doped heterostructure cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterial is 8-12 nm.

[0038] Secondly, this invention provides a method for preparing aluminum and phosphorus co-doped heterostructured cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterials, wherein the preparation method is as follows:

[0039] 1) Preparation of aluminum-doped cobalt tetroxide / nickel foam composite nanomaterials: In the presence of a first solvent, cobalt salt, aluminum salt and alkaline substance are first mixed, and then pretreated nickel foam is added to carry out a first hydrothermal reaction and calcined to obtain aluminum-doped cobalt tetroxide / nickel foam composite nanomaterials.

[0040] 2) Preparation of aluminum and phosphorus co-doped cobalt tetroxide / nickel foam composite nanomaterials: Under an inert atmosphere, the aluminum-doped cobalt tetroxide / nickel foam composite nanomaterials described in step 1) are phosphated with a phosphorus source to obtain aluminum and phosphorus co-doped cobalt tetroxide / nickel foam composite nanomaterials.

[0041] 3) Preparation of aluminum and phosphorus co-doped heterostructure cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterials: In the presence of a second solvent, nickel salt, iron salt and reducing agent are mixed and added to the aluminum and phosphorus co-doped cobalt tetroxide / nickel foam composite nanomaterials described in step 2) for a second hydrothermal reaction.

[0042] The method for preparing aluminum-phosphorus co-doped heterostructured cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterials of the present invention firstly grows Al-Co3O4 / NF on a three-dimensional NF conductive framework using a simple hydrothermal method and low-temperature calcination method. Subsequently, AP-Co3O4 / NF is obtained by low-temperature gas-phase phosphating. Finally, a secondary mild hydrothermal method is used to mix nickel salt, iron salt, and reducing agent in a solvent to obtain oxygen-vacancy-rich AP-Co3O4@NiFe2O4 / NF heterostructured composite nanomaterials. The present invention, by designing a suitable liquid-phase reaction system, facilitates ion diffusion and the release of gaseous products, providing a rapid electron channel for electrocatalysis. It has the advantages of simple operation, economical and environmentally friendly reagents, low cost, ease of operation, and suitability for mass production.

[0043] In a preferred embodiment of the present invention, in order to remove dust, oil and some oxides from the surface of the nickel foam, the pretreatment step includes: cutting the nickel foam into thin sheets of 3cm×4cm, soaking them in hydrochloric acid with a concentration of 6mol / L for 15min, rinsing them three times with deionized water and anhydrous ethanol respectively, and finally drying the nickel foam material in a vacuum drying oven at 50℃ for 10h before use.

[0044] In a preferred embodiment of the present invention, in order to obtain aluminum and phosphorus co-doped heterostructured cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterials with better catalytic activity, in step 1), the molar ratio of aluminum salt to cobalt salt is 1:2-25, wherein the aluminum salt is calculated on the basis of aluminum atoms and the cobalt salt is calculated on the basis of cobalt atoms. For example, the molar ratio of aluminum salt to cobalt salt can be 1:2, 1:5, 1:10, 1:15, 1:20 or 1:25.

[0045] In a preferred embodiment of the present invention, in order to obtain aluminum and phosphorus co-doped heterostructured cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterials with better catalytic activity, the cobalt salt is cobalt nitrate and / or cobalt sulfate.

[0046] In a preferred embodiment of the present invention, in order to obtain aluminum and phosphorus co-doped heterostructured cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterials with better catalytic activity, the aluminum salt is an aluminum nitrate and / or an aluminum sulfate.

[0047] In a preferred embodiment of the present invention, in order to obtain aluminum and phosphorus co-doped heterostructured cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterials with better catalytic activity, the alkaline substance is one or more of urea, ammonium fluoride and sodium carbonate.

[0048] In a preferred embodiment of the present invention, the concentration of the alkaline substance is 0.3-0.4 mol / L, preferably 0.357 mol / L.

[0049] In a preferred embodiment of the present invention, the first solvent is water, which can be common experimental and production water such as deionized water, ultrapure water, and distilled water.

[0050] In a preferred embodiment of the present invention, in step 1), the conditions for the first mixing include: a time of 20-40 min and a stirring rate of 600-1000 rpm, for example, a time of 20 min and a stirring rate of 600 rpm; a time of 25 min and a stirring rate of 700 rpm; a time of 30 min and a stirring rate of 800 rpm; a time of 35 min and a stirring rate of 900 rpm; or a time of 40 min and a stirring rate of 1000 rpm.

[0051] In a preferred embodiment of the present invention, in order to obtain aluminum and phosphorus co-doped heterostructured cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterials with better catalytic activity, the conditions for the first hydrothermal reaction include: under sealed conditions, a temperature of 100-160°C and a time of 8-14 hours, for example, a temperature of 100°C and a time of 8 hours; a temperature of 110°C and a time of 10 hours; a temperature of 120°C and a time of 12 hours; a temperature of 130°C and a time of 14 hours; a temperature of 140°C and a time of 14 hours; a temperature of 150°C and a time of 12 hours; or a temperature of 160°C and a time of 10 hours.

[0052] In a preferred embodiment of the present invention, in order to obtain aluminum and phosphorus co-doped heterostructured cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterials with better catalytic activity, the calcination conditions include: a temperature of 200-500℃ and a time of 1-4h, for example, a temperature of 200℃ and a time of 1h; a temperature of 300℃ and a time of 2h; a temperature of 400℃ and a time of 3h; or a temperature of 500℃ and a time of 4h.

[0053] In a preferred embodiment of the present invention, in order to obtain aluminum and phosphorus co-doped heterostructured cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterials with better catalytic activity, in step 2), the ratio of the phosphorus source to the aluminum-doped cobalt tetroxide / nickel foam composite nanomaterials is 1:1-4, wherein the phosphorus source is calculated in terms of phosphorus atoms, for example, the ratio of the phosphorus source to the aluminum-doped cobalt tetroxide / nickel foam composite nanomaterials is 1:1, 1:2, 1:3 or 1:4.

[0054] In a preferred embodiment of the present invention, in order to obtain aluminum and phosphorus co-doped heterostructured cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterials with better catalytic activity, the phosphorus source is sodium hypophosphite and / or red phosphorus.

[0055] In a preferred embodiment of the present invention, in order to obtain aluminum-phosphorus co-doped heterostructured cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterials with better catalytic activity, the phosphating conditions include: a temperature of 200-500℃, a time of 1-4h, and a heating rate of 15-25°C·min. -1 For example, the temperature is 200℃, the time is 1 hour, and the heating rate is 15°C·min. -1 The temperature was 300℃, the time was 2 hours, and the heating rate was 20°C·min. -1 The temperature was 400℃, the time was 3 hours, and the heating rate was 25°C·min. -1 Alternatively, the temperature can be 500℃ for 4 hours, with a heating rate of 20°C·min. -1 .

[0056] In a preferred embodiment of the present invention, the inert atmosphere is an argon atmosphere and / or a nitrogen atmosphere.

[0057] In a preferred embodiment of the present invention, in order to obtain aluminum and phosphorus co-doped heterostructured cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterials with better catalytic activity, in step 3), the molar ratio of nickel salt to iron salt is 1:1-6, wherein the nickel salt is calculated in terms of nickel atoms and the iron salt is calculated in terms of iron atoms; for example, the molar ratio of nickel salt to iron salt can be 1:1, 1:2, 1:3, 1:4, 1:5 or 1:6.

[0058] In a preferred embodiment of the present invention, the reducing agent is ascorbic acid and / or sodium citrate.

[0059] In a preferred embodiment of the present invention, the concentration of the reducing agent is 6-8 mmol / L, preferably 7 mmol / L.

[0060] In a preferred embodiment of the present invention, the second solvent is water, which can be common experimental and production water such as deionized water, ultrapure water, and distilled water.

[0061] In a preferred embodiment of the present invention, in order to obtain aluminum and phosphorus co-doped heterostructured cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterials with better catalytic activity, in step 3), the conditions for the second hydrothermal reaction include: under sealed conditions, a temperature of 100-160°C and a time of 8-14 hours, for example, a temperature of 100°C for 8 hours; a temperature of 110°C for 9 hours; a temperature of 120°C for 10 hours; a temperature of 130°C for 11 hours; a temperature of 140°C for 12 hours; a temperature of 150°C for 13 hours; or a temperature of 160°C for 14 hours.

[0062] Thirdly, the present invention provides an aluminum-phosphorus co-doped heterostructured cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterial prepared by the method described in the second aspect.

[0063] Fourthly, the present invention provides the application of the aluminum and phosphorus co-doped heterostructured cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterial described in the first or third aspect as an electrocatalyst in the catalytic electrolysis of water for oxygen evolution reaction.

[0064] The aluminum and phosphorus co-doped heterostructured cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterial of the present invention can be used as an electrocatalyst for the oxygen evolution reaction. The heterostructured aluminum and phosphorus co-doped cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterial can be used to catalyze the oxygen evolution reaction under alkaline conditions. It has good electrocatalytic oxygen evolution reaction activity, which is conducive to large-scale utilization and promotion.

[0065] The present invention will be described in detail below through examples. Unless otherwise specified, all pharmaceutical products used in the following examples are conventional commercially available products.

[0066] Example 1

[0067] (1) Before the experiment, cut the nickel foam into 3.0 × 4.0 cm pieces. 2Thin sheets were immersed in 6 M HCl for 15 min, and then rinsed three times with deionized water and anhydrous ethanol to remove surface oil and oxides. 2.5 mmol cobalt nitrate hexahydrate, 0.25 mmol aluminum nitrate nonahydrate, 5 mmol ammonium fluoride, and 7.5 mmol urea were added to 35.0 mL of deionized water and stirred continuously for 30 min to obtain a clear red solution. The mixed clear red solution was placed in a 50 mL high-pressure reactor containing clean nickel foam and hydrothermally reacted at 120°C for 10 h. After the reaction system cooled to room temperature, the product was removed, rinsed three times alternately with deionized water and anhydrous ethanol, and then dried in a vacuum oven at 60 °C. Subsequently, the product was calcined in a muffle furnace at 350 °C for 2 h to obtain aluminum-doped cobalt tetroxide / nickel foam composite nanomaterials, denoted as Al-Co3O4 / NF.

[0068] (2) Using the Al-Co3O4 / NF obtained in step (1) as a precursor and Na2HPO2 as a P source, Al-Co3O4 / NF and Na2HPO2 were placed in two different positions on the ceramic boat. Among them, 0.1 g of Na2HPO2 was placed upstream of the tube. In an Ar atmosphere, the mixture was heated at 2°C·min. -1 The aluminum-phosphorus co-doped cobalt tetroxide / nickel foam composite nanomaterial was prepared by heating at 350 °C for 2 h at a heating rate of AP-Co3O4 / NF.

[0069] (3) 0.25 mmol of nickel nitrate hexahydrate, 0.5 mmol of ferrous chloride tetrahydrate and 0.25 mmol of ascorbic acid were added to 35.0 mL of deionized water and stirred continuously for 30 min to obtain a clear green solution. The mixed clear green solution was placed into a 50 mL polytetrafluoroethylene high-pressure reactor containing AP-Co3O4 / NF and hydrothermally reacted at 180 °C for 10 h. After the reaction system cooled to room temperature, the product was taken out and washed three times alternately with deionized water and anhydrous ethanol. Then it was dried in a vacuum oven at 60 °C to obtain the aluminum and phosphorus co-doped heterostructure cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterial, which was named AP-Co3O4@NiFe2O4 / NF (Al doping amount was 1.19%).

[0070] Depend on Figure 1 The X-ray powder diffraction pattern of the aluminum-doped cobalt tetroxide / nickel foam composite nanomaterial obtained in step (1) of Example 1 shows that its main diffraction peaks correspond to the characteristic peaks of Co3O4 (PDF#43-1003) on the X-ray powder diffraction standard card, indicating that the product obtained in step (1) of Example 1 is Co3O4.

[0071] Depend on Figure 2The scanning electron microscope image of the aluminum-doped cobalt tetroxide / nickel foam composite nanomaterial obtained in step (1) of Example 1 shows that the Al-Co3O4 / NF prepared is a nanowire structure.

[0072] Depend on Figure 3 The scanning electron microscope image of the aluminum and phosphorus co-doped cobalt tetroxide / nickel foam composite nanomaterial obtained in step (2) of Example 1 shows that the phosphorus doping in step (2) did not change the shape and structure of the Al-Co3O4 / NF nanowires.

[0073] Depend on Figure 4 The X-ray powder diffraction pattern of the aluminum and phosphorus co-doped heterostructure cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterial in Example 1 shows that its main diffraction peaks are consistent with those of Co3O4 (PDF#43-1003) on the X-ray powder diffraction standard card, indicating that the product obtained in Example 1 is an AP-Co3O4@NiFe2O4 / NF composite material.

[0074] Depend on Figure 5 The scanning electron microscope image of the aluminum and phosphorus co-doped heterostructure cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterial in Example 1 shows that the AP-Co3O4@NiFe2O4 / NF composite material prepared in Example 1 is a heterostructure material with two-dimensional nanosheets grown on nanowires, and the thickness of its two-dimensional nanosheets is about 10 nm.

[0075] Depend on Figure 6 The transmission electron microscope (TEM) image of the aluminum-phosphorus co-doped heterostructure cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterial in Example 1 shows that the AP-Co3O4@NiFe2O4 / NF composite material prepared in Example 1 has a thin nanosheet structure uniformly grown on the surface of Co3O4 nanowires with a thickness of about 10 nm.

[0076] Example 2

[0077] The method of Example 1 was followed, except that “0.25 mmol aluminum nitrate nonahydrate” in step (1) was replaced with “0.125 mmol aluminum nitrate nonahydrate” to obtain an aluminum and phosphorus co-doped heterostructure cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterial, denoted as AP-Co3O4@NiFe2O4 / NF (Al doping amount 0.45%).

[0078] Depend on Figure 7 Scanning electron microscope images of the aluminum and phosphorus co-doped heterostructure cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterials in Example 2 show that the AP-Co3O4@NiFe2O4 / NF composite material prepared in Example 2 is a heterostructure material with two-dimensional nanosheets grown on nanowires, with a thickness of about 8 nm.

[0079] Example 3

[0080] The method of Example 1 was followed, except that “0.25 mmol aluminum nitrate nonahydrate” in step (1) was replaced with “0.5 mmol aluminum nitrate nonahydrate” to obtain an aluminum and phosphorus co-doped heterostructure cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterial, denoted as AP-Co3O4@NiFe2O4 / NF (Al doping amount 1.99%).

[0081] Depend on Figure 8 Scanning electron microscope images of the aluminum and phosphorus co-doped heterostructured cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterials in Example 3 show that the AP-Co3O4@NiFe2O4 / NF composite material prepared in Example 3 is a heterostructured material with two-dimensional nanosheets grown on nanowires, with a thickness of about 12 nm.

[0082] Example 4

[0083] The method of Example 1 was followed, except that “0.25 mmol aluminum nitrate nonahydrate” in step (1) was replaced with “0.75 mmol aluminum nitrate nonahydrate” to prepare aluminum and phosphorus co-doped heterostructure cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterials, denoted as AP-Co3O4@NiFe2O4 / NF (Al doping amount 2.54%).

[0084] Depend on Figure 9 Scanning electron microscope images of the aluminum and phosphorus co-doped heterostructured cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterials in Example 4 show that the AP-Co3O4@NiFe2O4 / NF composite material prepared in Example 4 is a heterostructured material with two-dimensional nanosheets grown on nanowires, with a thickness of about 9 nm.

[0085] Example 5

[0086] The method of Example 1 was followed, except that "hydrothermal reaction at 180 °C for 10 h" in step (3) was replaced with "hydrothermal reaction at 160 °C for 12 h" to obtain aluminum and phosphorus co-doped heterostructure cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterials, denoted as AP-Co3O4@NiFe2O4 / NF (Al doping amount 1.19%).

[0087] Depend on Figure 10 Scanning electron microscope images of the aluminum and phosphorus co-doped heterostructured cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterials in Example 5 show that the AP-Co3O4@NiFe2O4 / NF composite material prepared in Example 5 is a heterostructured material with two-dimensional nanosheets grown on nanowires, with a thickness of about 10 nm.

[0088] Comparative Example 1

[0089] The method of Example 1 was followed, except that "hydrothermal reaction at 180 °C for 10 h" in step (3) was replaced with "hydrothermal reaction at 120 °C for 10 h", and the resulting composite nanomaterial was denoted as D1 (Al doping amount 1.19%).

[0090] Depend on Figure 11 Scanning electron microscope images of the composite nanomaterials in Comparative Example 1 show that no thin nanosheet structure was grown on the Co3O4 nanowires. Compared with Example 1, Comparative Example 1 only reduced the temperature of the second hydrothermal reaction, which led to a significant change in the morphology of the nanomaterials. This shows that the experimental conditions of the present invention also need to be controlled and cannot be changed arbitrarily.

[0091] Comparative Example 2

[0092] The method of Example 1 was followed, except that "hydrothermal reaction at 180 °C for 10 h" in step (3) was replaced with "hydrothermal reaction at 200 °C for 10 h", and the resulting composite nanomaterial was denoted as D2 (Al doping amount 1.19%).

[0093] Depend on Figure 12 The scanning electron microscope image of the composite nanomaterial in Comparative Example 2 shows that the Co3O4 nanowire structure in the composite nanomaterial of Comparative Example 2 collapsed directly. Compared with Example 1, Comparative Example 2 only increased the temperature of the second hydrothermal reaction, which led to a significant change in the morphology of the nanomaterial. This shows that the experimental conditions of the present invention also need to be controlled and cannot be changed arbitrarily.

[0094] Comparative Example 3

[0095] The method of Example 1 was followed, except that the aluminum source in step (1) was not added and the phosphating in step (2) was not performed, and the cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterial was obtained, denoted as Co3O4@NiFe2O4 / NF.

[0096] Depend on Figure 13 The X-ray powder diffraction pattern of the cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterial of Comparative Example 3 shows that the main diffraction peaks of the cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterial of Comparative Example 3 correspond to the characteristic peaks of Co3O4 (PDF#43-1003) on the X-ray powder diffraction standard card. NiFe2O4 is amorphous, so there are no characteristic peaks corresponding to it, indicating that the product obtained in Comparative Example 3 is a cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterial.

[0097] Comparative Example 4

[0098] The method of Example 1 was followed, except that only step (3) was performed, and AP-Co3O4 / NF in step (3) was replaced with pretreated nickel foam to obtain nickel ferrite / nickel foam composite nanomaterial, denoted as NiFe2O4 / NF.

[0099] Depend on Figure 14 The scanning electron microscope image of the nickel ferrite / nickel foam composite nanomaterial in Comparative Example 4 shows that the nickel ferrite / nickel foam composite nanomaterial in Comparative Example 4 has a honeycomb-like two-dimensional nanosheet structure.

[0100] Application Example 1

[0101] The application of the aluminum-phosphorus co-doped heterostructured cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterial of the present invention in the field of catalytic water electrolysis oxygen evolution reaction, specifically the following application method:

[0102] The AP-Co3O4@NiFe2O4 / NF composite nanomaterials obtained in Example 1, the Co3O4@NiFe2O4 / NF composite nanomaterials obtained in Comparative Example 3, and the NiFe2O4 / NF composite nanomaterials obtained in Comparative Example 4 were used as catalysts to test their catalytic performance in the oxygen evolution reaction of water electrolysis in an alkaline environment. The steps are as follows:

[0103] At room temperature, 1 M KOH solution was used as the electrolyte solution for testing alkaline environments. A standard three-electrode system was used for testing, with a graphite rod as the counter electrode and a silver / silver chloride (Ag / AgCl) electrode as the reference electrode. The AP-Co3O4@NiFe2O4 / NF composite nanomaterials obtained in Example 1, the Co3O4@NiFe2O4 / NF composite nanomaterials obtained in Comparative Example 3, and the NiFe2O4 / NF composite nanomaterials obtained in Comparative Example 4 were cut into 1*1 cm pieces and clamped onto the electrode holder as working electrodes. The catalytic oxygen evolution reaction and hydrogen evolution reaction performance were tested using linear sweep voltammetry. The results are as follows: Figure 15 As shown.

[0104] Depend on Figure 15 The polarization curves of the AP-Co3O4@NiFe2O4 / NF composite nanomaterials obtained in Example 1, the Co3O4@NiFe2O4 / NF composite nanomaterials obtained in Comparative Example 3, and the NiFe2O4 / NF composite nanomaterials obtained in Comparative Example 4 in 1 mol / L KOH solution for catalyzing the oxygen evolution reaction can be seen. When the current density is 10 mA / cm²... 2At the same time, the overpotential of the Co3O4@NiFe2O4 / NF composite nanomaterial obtained in Comparative Example 3 was 331 mV, the overpotential of the NiFe2O4 / NF composite nanomaterial obtained in Comparative Example 4 was 251 mV, while the overpotential of the AP-Co3O4@NiFe2O4 / NF composite nanomaterial obtained in Example 1 was only 170 mV. The test results show that, compared with the Co3O4@NiFe2O4 / NF composite nanomaterial obtained in Comparative Example 3 and the NiFe2O4 / NF composite nanomaterial obtained in Comparative Example 4, the AP-Co3O4@NiFe2O4 / NF composite nanomaterial prepared by the preparation method of the present invention has better catalytic oxygen evolution reaction performance in alkaline environment, can provide better economic benefits, and thus can be better applied.

[0105] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of 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 protection scope of the present invention.

[0106] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0107] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A composite nanomaterial with an aluminum and phosphorus co-doped heterostructure of cobalt tetroxide / nickel ferrite / nickel foam, characterized in that, The chemical formula of the aluminum-phosphorus co-doped heterostructured cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterial is AP-Co3O4@NiFe2O4 / NF, wherein... The structure of the aluminum and phosphorus co-doped heterostructure cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterial is a heterostructure in which two-dimensional nanosheets are grown on nanowires. The thickness of the aluminum and phosphorus co-doped heterostructure cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterial is 8-12 nm. The preparation method of the aluminum and phosphorus co-doped heterostructured cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterial is as follows: 1) Preparation of aluminum-doped cobalt tetroxide / nickel foam composite nanomaterials: In the presence of a first solvent, cobalt salt, aluminum salt and alkaline substance are first mixed, and then pretreated nickel foam is added to carry out a first hydrothermal reaction and calcined to obtain aluminum-doped cobalt tetroxide / nickel foam composite nanomaterials. 2) Preparation of aluminum and phosphorus co-doped cobalt tetroxide / nickel foam composite nanomaterials: Under an inert atmosphere, the aluminum-doped cobalt tetroxide / nickel foam composite nanomaterials described in step 1) are phosphated with a phosphorus source to obtain aluminum and phosphorus co-doped cobalt tetroxide / nickel foam composite nanomaterials. 3) Preparation of aluminum and phosphorus co-doped heterostructure cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterials: In the presence of a second solvent, nickel salt, iron salt and reducing agent are mixed and added to the aluminum and phosphorus co-doped cobalt tetroxide / nickel foam composite nanomaterials described in step 2) for a second hydrothermal reaction.

2. The aluminum and phosphorus co-doped heterostructured cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterial according to claim 1, characterized in that, In step 1), the molar ratio of the aluminum salt to the cobalt salt is 1:2-25, wherein the aluminum salt is calculated as aluminum atoms and the cobalt salt is calculated as cobalt atoms; The cobalt salt is a cobalt nitrate and / or a cobalt sulfate; The aluminum salt is an aluminum nitrate and / or an aluminum sulfate; The alkaline substance is one or more of urea, ammonium fluoride and sodium carbonate; The concentration of the alkaline substance is 0.3-0.4 mol / L; The first solvent is water.

3. The aluminum-phosphorus co-doped heterostructured cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterial according to claim 1 or 2, characterized in that, In step 1), the conditions for the first mixing include: a time of 20-40 min and a stirring rate of 600-1000 rpm; The conditions for the first hydrothermal reaction include: under closed conditions, a temperature of 100-160℃ and a time of 8-14h; The calcination conditions include a temperature of 200-500℃ and a time of 1-4 hours.

4. The aluminum and phosphorus co-doped heterostructured cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterial according to claim 1, characterized in that, In step 2), the mass ratio of the phosphorus source to the aluminum-doped cobalt tetroxide / nickel foam composite nanomaterial is 1:1-4, wherein the phosphorus source is expressed in terms of phosphorus atoms; The phosphorus source is sodium hypophosphite and / or red phosphorus; The phosphating conditions include: a temperature of 200-500℃, a time of 1-4 hours, and a heating rate of 15-25℃·min. -1 ; The inert atmosphere is an argon atmosphere and / or a nitrogen atmosphere.

5. The aluminum and phosphorus co-doped heterostructured cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterial according to claim 1, characterized in that, In step 3), the molar ratio of the nickel salt to the iron salt is 1:1-6, wherein the nickel salt is calculated as nickel atoms and the iron salt is calculated as iron atoms; The reducing agent is ascorbic acid and / or sodium citrate; The concentration of the reducing agent is 6-8 mmol / L; The second solvent is water.

6. The aluminum and phosphorus co-doped heterostructured cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterial according to claim 1, characterized in that, In step 3), the conditions for the second hydrothermal reaction include: under closed conditions, the temperature is 100-160℃ and the time is 8-14h.

7. The application of the aluminum and phosphorus co-doped heterostructured cobalt tetroxide / nickel ferrite / nickel foam composite nanomaterial as an electrocatalyst in the catalytic electrolysis of water for oxygen evolution reaction according to any one of claims 1-6.

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