Electro-catalytic oxygen evolution electrode with self-supporting heterostructure and preparation method and application of electro-catalytic oxygen evolution electrode

Abstract

The invention discloses a self-supporting heterostructure electro-catalysis oxygen evolution electrode and a preparation method and application thereof, and relates to the technical field of water electrolysis hydrogen production. A novel three-dimensional composite material with a nanorod (Ni3S2) loaded high-activity nanocluster (FeS / MoS2) heterostructure is directly grown on foamed nickel through a simple two-step hydrothermal method. The short rod-shaped Ni3S2 synthesized in the first step is beneficial to adsorption of reactants (H2O and OH <->) and formation of intermediates (such as O * and OOH *), and the FeS / MoS2 / Ni3S2 (at) NF synthesized in the second step is characterized in that FeS provides a large number of active sites, and MoS2 optimizes a heterostructure electronic structure. The FeS / MoS2 / Ni3S2 (at) NF has relatively small charge transfer resistance and excellent electro-catalytic performance. The material has excellent OER performance in a 1M KOH solution, keeps a long service life, and has an application prospect in oxygen evolution batteries.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of hydrogen production by electrolysis of water, and particularly relates to a self-supporting heterostructure electrocatalytic oxygen evolution electrode and a preparation method and application thereof. BACKGROUND

[0002] Under the background of rapid rise of global energy demand and increasingly serious environmental pollution, it is urgent to develop renewable energy and clean energy. Hydrogen energy, as a kind of renewable and clean energy, is expected to become one of the core energies of the "third industrial revolution" due to its clean, efficient and flexible characteristics. Electrocatalytic water splitting is a chemical reaction process for splitting water (H2O) into hydrogen (H2) and oxygen (O2) driven by electrical energy. The process is divided into two half-reactions: the cathode reduction reaction produces hydrogen, and the anode oxidation reaction produces oxygen. However, the anode oxygen evolution reaction (OER) has the problem of reaction kinetic lag, which leads to a high energy barrier, seriously affecting the water splitting rate and thus reducing the hydrogen production efficiency. Therefore, people are committed to developing an efficient and economical electrocatalyst.

[0003] Trinickel disulfide (Ni3S2) has high electrical conductivity, rich active sites and controllable electronic structure. Ferrous sulfide (FeS) can form high active sites and multi-functional composite due to the existence of sulfur vacancies, and has great advantages in OER. Molybdenum disulfide (MoS2) is rich in resources, and the introduction of sulfur vacancies or unsaturated coordination of Mo sites can optimize the adsorption energy of OER intermediates (*OH, *O). Here, a simple two-step hydrothermal method is used to directly grow a new type of three-dimensional composite material of nanorod (Ni3S2) loaded with high-activity nanocluster (FeS / MoS2) heterostructure on foam nickel, which has a large number of active sites and can effectively reduce the overpotential. SUMMARY

[0004] In order to overcome the above-mentioned shortcomings of the prior art, the purpose of the present application is to provide a self-supporting heterostructure electrocatalytic oxygen evolution electrode and a preparation method and application thereof, so as to solve the technical problems of high energy barrier and reaction kinetic lag in the oxygen evolution reaction process.

[0005] In order to achieve the above-mentioned purpose, the present application adopts the following technical solutions: In a first aspect, the present application provides a preparation method of a self-supporting heterostructure electrocatalytic oxygen evolution electrode, comprising the following steps: Step 1: ultrasonic washing and drying of foam nickel to obtain pretreated foam nickel; Step 2: dissolving a sulfur source in a mixed solution of ethylene glycol and deionized water, ultrasonic treatment until complete dissolution, then carrying out hydrothermal reaction of the obtained solution and the pretreated foam nickel, cooling to room temperature after reaction, washing and drying to obtain Ni3S2 / NF; Step 3, dissolving the molybdenum source, iron source and sulfur source in a mixed solution of ethylene glycol and deionized water, ultrasonic treatment until completely dissolved, then the obtained solution and the Ni3S2@NF are subjected to hydrothermal reaction, after the reaction is completed, cooling to room temperature, washing, drying to obtain FeS / MoS2 / Ni3S2@NF.

[0006] Further improvement of the application is that in step 1, the foam nickel is sequentially ultrasonically washed by dilute hydrochloric acid, acetone, anhydrous ethanol and deionized water, wherein the concentration of dilute hydrochloric acid is 3M, the drying temperature is 50-70℃, and the drying time is 5-7h.

[0007] Further improvement of the application is that in step 1, the thickness of the foam nickel is 0.5-1mm, the pore density is 100-130PPI, and the pore size is 0.1-0.3mm.

[0008] Further improvement of the application is that in step 2, the volume ratio of the mixed solution of ethylene glycol and deionized water is 1:4-1:5, the ultrasonic treatment time is 15-25min, the hydrothermal reaction temperature is 160-170℃, the reaction time is 5-6h, the drying temperature is 50-70℃, and the drying time is 7-9h.

[0009] Further improvement of the application is that in step 2, the sulfur source is thiourea, and the molar ratio of the sulfur source to the foam nickel is 1:1-1:1.5.

[0010] Further improvement of the application is that in step 3, the molybdenum source is sodium molybdate dihydrate, the iron source is ferrous chloride tetrahydrate, and the sulfur source is thiourea; wherein the molar ratio of the molybdenum source, the iron source and the sulfur source is 1:1.5:3.5-1:2:4, the volume ratio of the mixed solution of ethylene glycol and deionized water is 1:4-1:5, the ultrasonic treatment time is 15-25min, the hydrothermal reaction temperature is 160-180℃, the reaction time is 10-11h, the drying temperature is 50-70℃, and the drying time is 7-9h.

[0011] Further improvement of the application is that in steps 2 and 3, after the hydrothermal reaction is completed, the foam nickel is washed with anhydrous ethanol and deionized water for 2-3 times.

[0012] In the second aspect, the application further provides a hydrogen evolution electrode prepared by the above-mentioned preparation method of self-supporting heterostructure electrocatalytic oxygen evolution electrode.

[0013] In the third aspect, the application further provides an electrode material of oxygen evolution battery, which is prepared from the above-mentioned hydrogen evolution electrode.

[0014] In the fourth aspect, the application further provides an application of the above-mentioned oxygen evolution electrode in electrocatalytic oxygen evolution reaction.

[0015] Compared with the prior art, the present application has the following beneficial effects: The present application provides a preparation method of a self-supporting heterostructure electrocatalytic oxygen evolution electrode, FeS / MoS2 / Ni3S2@NF heterostructure is prepared on the nickel foam by two-step hydrothermal method. First, the nickel foam is pretreated to ensure the cleanliness of the substrate surface, providing uniform nucleation points for subsequent in-situ growth and reducing impurity interference; second, by taking advantage of the solubility of sulfur source in ethylene glycol-water mixed solvent, Ni3S2 nanorods are grown directly on the nickel foam by hydrothermal reaction, and then FeS / MoS2 nanoclusters are loaded on the Ni3S2 nanorods by hydrothermal reaction to form nanorod-nanocluster heterostructure. This structure makes full use of the high specific surface area support of Ni3S2 nanorods and the synergistic effect of FeS and MoS2, significantly increasing the active site density. The use of ethylene glycol-water mixed solvent promotes the uniform dissolution and diffusion of the precursor, making the heterojunction interface more compact, optimizing the electronic structure and accelerating the charge transport. The preparation method of the present application is simple, mild and low-cost, the material raw materials are cheap, suitable for large-scale production, and the composite structure is precisely controlled by step-by-step hydrothermal method, avoiding the phase separation problem of multi-component co-deposition.

[0016] The present application also provides an oxygen evolution electrode, which takes nickel foam as the substrate, and its three-dimensional porous structure endows the electrode with high electrical conductivity and mechanical toughness, which is beneficial to the diffusion of reactants and the detachment of bubbles. Ni3S2 nanorods act as a support framework, which not only exposes a large number of active crystal faces, but also forms a tight heterojunction with FeS / MoS2 nanoclusters, producing an interface electron reconstruction effect, which reduces the adsorption energy of hydrogen evolution reaction intermediate (H), thereby significantly reducing the overpotential. The introduction of FeS enhances the metallic properties of the material and improves the electrical conductivity, while the synergistic effect of the edge sulfur atoms of MoS2 and FeS further optimizes the hydrogen adsorption free energy, reduces the Tafel slope and accelerates the reaction kinetics. In addition, the self-supporting characteristic avoids the use of adhesives, preventing the active material from falling off during use. The electrode raw materials are cheap, and no noble metal is needed, which greatly reduces the cost of hydrogen production, especially suitable for industrial applications of alkaline water electrolysis. BRIEF DESCRIPTION OF DRAWINGS

[0017] The drawings described herein are for illustrative purposes only and are not intended to limit the scope of the present application in any way. In addition, the shapes and scale of the components in the figures are only illustrative and are used to help understand the present application, and are not specific limitations on the shapes and scale of the components of the present application.

[0018] Figure 1 XRD patterns of FeS / MoS2 / Ni3S2@NF, MoS2 / Ni3S2@NF, FeS / Ni3S2@NF and Ni3S2@NF prepared for Examples 1 to 3 of the present application; Figure 2 SEM images of Ni3S2@NF and FeS / MoS2 / Ni3S2@NF prepared for Example 1 of the present application; Figure 3 TEM images of FeS / MoS2 / Ni3S2@NF prepared for Example 1 of the present application; Figure 4 Comparison chart of double-layer capacitance of FeS / MoS2 / Ni3S2@NF, MoS2 / Ni3S2@NF, FeS / Ni3S2@NF and Ni3S2@NF prepared for Examples 1 to 3 of the present application; Figure 5 Comparison results of oxygen evolution performance of FeS / MoS2 / Ni3S2@NF, MoS2 / Ni3S2@NF, FeS / Ni3S2@NF and Ni3S2@NF electrode materials prepared for Examples 1 to 3 of the present application; Figure 6 Comparison chart of Tafel slope of FeS / MoS2 / Ni3S2@NF, MoS2 / Ni3S2@NF, FeS / Ni3S2@NF and Ni3S2@NF prepared for Examples 1 to 3 of the present application; Figure 7 FeS / MoS2 / Ni3S2@NF electrode material prepared for Example 1 of the present application in 100 mA cm-2 -2 Long-term durability test at constant high current density. DETAILED DESCRIPTION

[0019] To enable persons skilled in the art to understand the features and effects of the present application, the following is a general description and definition of the terms and phrases mentioned in the specification and claims. Unless otherwise specified, all technical and scientific words used herein have their usual meanings understood by those skilled in the art of the present application, and in the event of a conflict, the definitions in the specification shall prevail.

[0020] Theories or mechanisms described and disclosed herein, whether correct or not, should not be regarded as limiting the scope of the present application, i.e., the present application can be practiced without regard to any particular theory or mechanism.

[0021] Herein, all features defined in the form of numerical ranges or percentage ranges such as values, amounts, contents and concentrations are for the sake of brevity and convenience. Accordingly, the description of numerical ranges or percentage ranges should be considered to have encompassed and specifically disclosed all possible sub-ranges and individual numerical values within the range (including integers and fractions).

[0022] In the present specification, unless particularly stated, "comprising", "including", "containing", "having" or like terms, are intended to encompass the meaning of "consisting of" and "consisting essentially of", for example, "A comprising a" encompasses the meaning of "A comprising a and other" and "A consisting of a".

[0023] In the present specification, all possible combinations of the technical features in the various embodiments or examples are not described in order to make the description concise. Therefore, as long as the combinations of the technical features do not contradict each other, the technical features in the various embodiments or examples can be combined arbitrarily, and all possible combinations should be considered as falling within the scope of the present specification.

[0024] The present application provides a preparation method of a self-supporting heterostructure electrocatalytic oxygen evolution electrode, comprising the following steps: Step 1, the foam nickel is sequentially washed by dilute hydrochloric acid, acetone, anhydrous ethanol and deionized water under ultrasonic, and then dried to obtain pretreated foam nickel; Step 2, the sulfur source is dissolved in a mixed solution of ethylene glycol and deionized water, and ultrasonic treatment is carried out until complete dissolution, then the obtained solution and the pretreated foam nickel are subjected to hydrothermal reaction, after the reaction is completed, it is cooled to room temperature, washed with anhydrous ethanol and deionized water for 2-3 times, and dried to obtain Ni3S2 / NF; Step 3, the molybdenum source, iron source and sulfur source are dissolved in a mixed solution of ethylene glycol and deionized water, and ultrasonic treatment is carried out until complete dissolution, then the obtained solution and the Ni3S2 / NF are subjected to hydrothermal reaction, after the reaction is completed, it is cooled to room temperature, washed with anhydrous ethanol and deionized water for 2-3 times, and dried to obtain FeS / MoS2 / Ni3S2 / NF.

[0025] In some embodiments, in step 1, the concentration of dilute hydrochloric acid is 3M, the drying temperature is 50-70℃, and the drying time is 5-7h; the thickness of the foam nickel is 0.5-1mm, the pore density is 100-130PPI, and the pore size is 0.1-0.3mm.

[0026] In some embodiments, in step 2, the volume ratio of the mixed solution of ethylene glycol and deionized water is 1:1-1:1.5, the ultrasonic treatment time is 15-25min, the hydrothermal reaction temperature is 160-170℃, the reaction time is 5-6h, the drying temperature is 50-70℃, and the drying time is 7-9h.

[0027] As a preferred solution, the sulfur source is thiourea, wherein the molar ratio of the sulfur source to the foam nickel is 1:1-1:1.5.

[0028] As a preferred solution, in step 3, the molybdenum source is sodium molybdate dihydrate, the iron source is ferrous chloride tetrahydrate, and the sulfur source is thiourea; wherein the molar ratio of the molybdenum source, the iron source and the sulfur source is 1:1.5:3.5~1:2:4, the volume ratio of the mixed solution of ethylene glycol and deionized water is 1:4~1:5, the ultrasonic treatment time is 15~25min, the hydrothermal reaction temperature is 160~180℃, the reaction time is 10~11h, the drying temperature is 50~70℃, and the drying time is 7~9h.

[0029] The application further provides an electrocatalytic oxygen evolution electrode prepared based on the method, which can be used in an oxygen evolution battery, and comprises electrode materials for preparing the oxygen evolution battery, and has a large number of active sites and the advantage of effectively reducing overpotential.

[0030] The application further provides an application of a hydrogen evolution electrode in an electrocatalytic hydrogen evolution reaction.

[0031] The application will be further described below in combination with specific examples. It should be understood that the examples are only used to illustrate the application but not to limit the scope of the application. In addition, it should be understood that those skilled in the art can make various modifications or changes to the application after reading the content of the application, and these equivalent forms also fall within the scope defined by the appended claims of the application.

[0032] The following examples use the conventional instrument equipment in the art. The experimental methods in the following examples not noted with specific conditions are usually carried out according to the conventional conditions or the conditions suggested by the manufacturers. The various raw materials used in the following examples are all conventional commercially available products, unless otherwise specified, and the specifications are conventional specifications in the art. In the specification of the application and the following examples, unless otherwise specified, "%" means weight percent, "parts" means weight parts, and the ratio means weight ratio.

[0033] Example 1 The embodiment provides a preparation method of a self-supporting FeS / MoS2 / Ni3S2@NF heterostructure electrocatalytic oxygen evolution electrode, comprising the following steps: 1) Cut the nickel foam to the required size (1cm×2cm) (deviation between different plates <0.05cm). Ultrasonically treat the nickel foam in 3M dilute hydrochloric acid solution, acetone, anhydrous ethanol and deionized water in sequence for 15min to remove the surface oxidation layer, and then dry in a 70℃ vacuum oven for 5h to obtain pretreated nickel foam; 2) Dissolve 3 mmol thiourea in a mixed solution of 8 mL ethylene glycol and 32 mL deionized water, ultrasonic treatment for 15 min until completely dissolved, then transfer it and two pieces of pretreated foam nickel into a 100 mL polytetrafluoroethylene lined stainless steel autoclave, react at 160 °C for 6 h, after cooling to room temperature, rinse the sample with absolute ethanol and deionized water twice, dry in a vacuum drying oven at 50 °C for 9 h, to obtain Ni3S2@NF material; 3) Dissolve 0.4 mmol sodium molybdate dihydrate, 0.6 mmol ferrous chloride tetrahydrate and 1.4 mmol thiourea in 10 ml ethylene glycol and 40 ml deionized water, ultrasonic treatment for 15 min until completely dissolved, then transfer it and two pieces of Ni3S2@NF into a 100 ml polytetrafluoroethylene lined stainless steel autoclave, react at 160 °C for 11 h, after cooling to room temperature, rinse the sample with absolute ethanol and deionized water twice, dry in a vacuum drying oven at 50 °C for 9 h, to obtain FeS / MoS2 / Ni3S2@NF electrocatalytic oxygen evolution electrode.

[0034] Example 2 The present embodiment provides a preparation method of a self-supporting FeS / Ni3S2@NF heterostructure electrocatalytic oxygen evolution electrode, comprising the following steps: 1) Cut the foam nickel to the required size (1 cm x 2 cm) (deviation between different plates <0.05 cm). Ultrasonic treatment of the foam nickel in 3M dilute hydrochloric acid solution, acetone, absolute ethanol and deionized water for 15 min in turn to remove the surface oxide layer, then dry in a vacuum oven at 50 °C for 7 h to obtain pretreated foam nickel; 2) Dissolve 3 mmol thiourea in a mixed solution of 8 mL ethylene glycol and 32 mL deionized water, ultrasonic treatment for 20 min until completely dissolved, then transfer it and two pieces of pretreated foam nickel into a 100 mL polytetrafluoroethylene lined stainless steel autoclave, react at 165 °C for 5.5 h, after cooling to room temperature, rinse the sample with absolute ethanol and deionized water twice, dry in a vacuum drying oven at 70 °C for 7 h, to obtain Ni3S2@NF material; 3) Dissolve 0.6 mmol ferrous chloride tetrahydrate and 1.4 mmol thiourea in 10 ml ethylene glycol and 40 ml deionized water, ultrasonic treatment for 20 min until completely dissolved, then transfer it and two pieces of Ni3S2@NF into a 100 ml polytetrafluoroethylene lined stainless steel autoclave, react at 170 °C for 10.5 h, after cooling to room temperature, rinse the sample with absolute ethanol and deionized water three times, dry in a vacuum drying oven at 60 °C for 8 h, to obtain FeS / Ni3S2@NF electrocatalytic oxygen evolution electrode.

[0035] Example 3 The embodiment provides a preparation method of a self-supporting MoS2 / Ni3S2 / NF heterostructure electrocatalytic oxygen evolution electrode, and comprises the following steps: 1) Foam nickel is cut to a required size (1 cm x 2 cm) (deviation between different plates <0.05 cm). The foam nickel is sequentially subjected to ultrasonic treatment in 3M dilute hydrochloric acid solution, acetone, anhydrous ethanol and deionized water for 25 min to remove the surface oxidation layer, and then is dried in a 60 DEG C vacuum oven for 6 h to obtain pretreated foam nickel; 2) 3 mmol of thiourea is dissolved in a mixed solution of 8 mL of ethylene glycol and 32 mL of deionized water, is subjected to ultrasonic treatment for 25 min until completely dissolved, and then is transferred into a 100 mL polytetrafluoroethylene-lined stainless steel autoclave together with two pieces of pretreated foam nickel, and is reacted at 170 DEG C for 5 h. After cooling to room temperature, the sample is washed with anhydrous ethanol and deionized water twice respectively, and is dried in a 60 DEG C vacuum drying box for 8 h to obtain a Ni3S2@NF material; 3) 0.4 mmol of sodium molybdate dihydrate and 1.4 mmol of thiourea are dissolved in 10 ml of ethylene glycol and 40 ml of deionized water, are subjected to ultrasonic treatment for 25 min until completely dissolved, and then are transferred into a 100 ml polytetrafluoroethylene-lined stainless steel autoclave together with two pieces of Ni3S2@NF, and are reacted at 180 DEG C for 10 h. After cooling to room temperature, the sample is washed with anhydrous ethanol and deionized water twice respectively, and is dried in a 70 DEG C vacuum drying box for 7 h to obtain a MoS2 / Ni3S2@NF electrocatalytic oxygen evolution electrode.

[0036] Performance test (1) The FeS / MoS2 / Ni3S2@NF, FeS / Ni3S2@NF, MoS2 / Ni3S2@NF and Ni3S2@NF of the embodiments 1-3 are subjected to X-ray diffraction (XRD) test, and the results are shown in Figure 1 .

[0037] The XRD patterns are shown in the figure. It was found that the characteristic diffraction peaks of all samples matched those of crystalline Ni3S2 (PDF#73-0698), showing distinct peaks at 22.3°, 31.7°, 38.3°, 50.1°, and 55.7°. These peaks correspond to the (100), (-110), (111), (210), and (21-1) crystal planes of Ni3S2, confirming the formation of Ni3S2 on the NF surface. Comparing with the Ni (PDF#87-0712) standard card, the characteristic diffraction peaks of Ni3S2@NF are consistent, while the intensity of the Ni characteristic diffraction peaks in FeS / MoS2 / Ni3S2@NF, MoS2 / Ni3S2@NF, and FeS / Ni3S2@NF is significantly reduced. This indicates that the formation of new MoS2 and FeS phases on the surface occupies volume, reduces the number of effective nickel grains, and weakens the diffraction signal of the original nickel phase. The presence of Ni3S2 and Ni in all products indicates partial sulfidation of NF during the hydrothermal process. With the addition of Fe and Mo salts, the intensity of the characteristic diffraction peaks is significantly higher than that with only Fe and Mo salts, indicating improved crystal structure order. This suggests that the addition of MoS2 and FeS is beneficial for increasing the crystallinity of Ni3S2. No diffraction peaks related to MoS2 and FeS were observed in FeS / MoS2 / Ni3S2@NF, MoS2 / Ni3S2@NF, and FeS / Ni3S2@NF, which may be attributed to their low content and amorphous characteristics.

[0038] (2) Scanning electron microscopy (SEM) tests were performed on Ni3S2@NF and FeS / MoS2 / Ni3S2@NF from Example 1 of the present invention. The results are as follows: Figure 2 As shown.

[0039] like Figure 2 As shown in Figures a and 2b, SEM results indicate that the Ni3S2@NF heterojunction has a short rod-like structure, while the FeS / MoS2 / Ni3S2@NF heterojunction has a long rod-like structure doped with some cluster structures. The diameter of the nanorods is mainly between 40-120 nm, and the length is over 1000 nm. The diameter of the cluster structures is mainly around 80 nm. Compared with Ni3S2@NF, the long rod-like and cluster-like structures of FeS / MoS2 / Ni3S2@NF have a larger specific surface area, exposing more active sites in the electrolyte. The long rod-like structure is conducive to the formation of more ordered electron transport channels, which is more favorable for kinetics. These factors can improve the catalytic activity of the OER catalyst.

[0040] (3) The FeS / MoS2 / Ni3S2@NF of Example 1 of the present invention was tested by transmission electron microscopy (TEM), and the results are as follows: Figure 3 As shown.

[0041] Figure 3 The high-resolution transmission electron microscopy (HRTEM) of FeS / MoS2 / Ni3S2@NF is shown, in which clear lattices can be observed, the lattice with a spacing of 0.271 nm corresponds to the (200) plane of FeS, the lattice with a spacing of 0.287 nm corresponds to the (110) plane of Ni3S2, and an unordered lattice region appears between the two interfaces, which further confirms the strong interaction between the (110) plane of Ni3S2 and the (200) plane of FeS (32). In addition, the lattice with a spacing of 0.410 nm corresponds to the (101) plane of Ni3S2 and the (200) plane of FeS, and the lattice with a spacing of 0.267 nm corresponds to the (100) plane of MoS2 and the (110) plane of Ni3S2, clear interfaces are observed between them, which indicates the successful generation of FeS / MoS2 / Ni3S2@NF heterostructure. At the same time, obvious lattice fringe dislocations and deformations are observed in the figure, revealing the absence of atoms, indicating that there are a large number of defects in the structure. Previous reports have shown that the presence of a large number of defects and unordered regions on the interface can provide additional active centers, which is conducive to promoting charge transfer and is a favorable condition for improving the HER / OER reaction activity.

[0042] (4) The double-layer capacitances of FeS / MoS2 / Ni3S2@NF, MoS2 / Ni3S2@NF, FeS / Ni3S2@NF and Ni3S2@NF of embodiments 1-3 of the present application were compared, and the results are shown in Figure 4

[0043] Figure 4 The relationship between the scan rate and current density of each material is described, and it can be clearly seen that the Cdl of FeS / MoS2 / Ni3S2@NF is 12.32 mF·cm -2 ), which is significantly higher than that of MoS2 / Ni3S2@NF (3.71 mF·cm -2 ), FeS / Ni3S2@NF (7.28 mF·cm -2 ), Ni3S2@NF (5.08 mF·cm -2 ) and NF (1.34 mF·cm -2 ). These results show that the synergistic effect between FeS, MoS2 and Ni3S2 leads to a significant increase in the electrochemically active area, thereby improving its OER performance.

[0044] (5) The performance of FeS / MoS2 / Ni3S2@NF, MoS2 / Ni3S2@NF, FeS / Ni3S2@NF and Ni3S2@NF electrode materials in the oxygen evolution of embodiments 1-3 of the present application was compared, and the results are shown in Figure 5 .​

[0045] FeS / MoS2 / Ni3S2@NF at 10, 50, and 100 mA·cm -2 The voltage levels at the points below are 225, 309, and 393 mV, which are lower than those at MoS2 / Ni3S2@NF (459 mV @ 100 mA·cm). -2 ), FeS / Ni3S2@NF (408mV@100mA·cm -2 ), Ni3S2@NF (542mV@100mA·cm -2 and NF (594mV@100mA·cm) -2 This indicates that the electrocatalyst we prepared has high catalytic activity. Secondly, it can be seen that adding MoS2 alone improves the catalytic activity compared to Ni3S2@NF; adding FeS alone improves the catalytic activity and reduces the intensity of the Ni redox peak compared to Ni3S2 / NF; and adding both MoS2 and FeS further reduces the Ni redox peak intensity and further improves the catalytic activity compared to MoS2 / Ni3S2@NF and FeS / Ni3S2@NF. Two main reasons explain this phenomenon. First, the presence of FeS optimizes the electronic structure of Ni3S2, reducing the charge density near Ni atoms and thus lowering the Ni redox peak intensity. Second, the synergistic effect between MoS2 and FeS with Ni3S2 promotes charge transfer, lowers the Gibbs free energy of the OER, and improves the catalytic efficiency.

[0046] (6) The Tafel slopes of FeS / MoS2 / Ni3S2@NF, MoS2 / Ni3S2@NF, FeS / Ni3S2@NF, and Ni3S2@NF in Examples 1-3 of the present invention were compared, and the structures are as follows: Figure 6 As shown.

[0047] like Figure 6 As shown, the Tafel slope of FeS / MoS2 / Ni3S2@NF (72 mV·dec) -1 (82 mV·dec) lower than MoS2 / Ni3S2@NF -1 ), FeS / Ni3S2@NF (107 mV·dec -1 Ni3S2@NF (116mV·dec) -1 ) and NF (190mV·dec -1). It is clear that FeS / MoS2 / Ni3S2@NF has the lowest Tafel slope. This indicates that FeS / MoS2 / Ni3S2@NF exhibits the fastest reaction kinetics due to the synergistic effect between Ni3S2, MoS2 and FeS.

[0048] (7) The FeS / MoS2 / Ni3S2@NF electrode material of Example 1 of the present application was tested at 100 mA cm-2 -2 The results are shown in Figure 8. Figure 7

[0049] In order to accurately evaluate the OER durability of FeS / MoS2 / Ni3S2@NF, a 30h test was carried out at 100 mA·cm-2 2 The results are shown in Figure 9. Figure 7 The results show that the FeS / MoS2 / Ni3S2@NF catalyst has good electrocatalytic performance and stability for OER reaction under alkaline conditions.

[0050] In summary, the present application provides a FeS / MoS2 / Ni3S2@NF heterostructure prepared on foam nickel by a two-step hydrothermal method. This reasonable design makes the prepared catalyst have excellent OER performance (η10=225mV, η50=309mV, η100=393mV) in 1M KOH solution, and maintains a long working life (20h) at 100 mA·cm-2 -2 current density. Structural characterization shows that the nanorod (Ni3S2)-nanocluster (FeS / MoS2) heterostructure can provide more active sites and optimize the electronic structure of the Ni3S2 surface, thereby improving the OER catalytic activity. The prepared FeS / MoS2 / Ni3S2@NF heterojunction has great potential for water splitting to produce hydrogen.

[0051] The above content is only to illustrate the technical idea of the present application, and cannot limit the protection scope of the present application. Any modification made according to the technical idea of the present application on the basis of the technical solution falls within the protection scope of the claims of the present application.​

Claims

1. A method for preparing a self-supporting heterostructure electrocatalytic oxygen evolution electrode, characterized in that, Includes the following steps: Step 1: The nickel foam is ultrasonically washed and dried to obtain pretreated nickel foam; Step 2: Dissolve the sulfur source in a mixed solution of ethylene glycol and deionized water, sonicate until completely dissolved, and then perform a hydrothermal reaction between the resulting solution and the pretreated nickel foam. After the reaction is completed, cool to room temperature, wash and dry to obtain Ni3S2 / NF. Step 3: Dissolve the molybdenum source, iron source, and sulfur source in a mixed solution of ethylene glycol and deionized water, sonicate until completely dissolved, and then perform a hydrothermal reaction between the resulting solution and the Ni3S2@NF. After the reaction is completed, cool to room temperature, wash, and dry to obtain FeS / MoS2 / Ni3S2@NF.

2. The method for preparing a self-supporting heterostructure electrocatalytic oxygen evolution electrode according to claim 1, characterized in that, In step 1, the nickel foam is ultrasonically washed sequentially with dilute hydrochloric acid, acetone, anhydrous ethanol and deionized water, wherein the concentration of dilute hydrochloric acid is 3M, the drying temperature is 50~70℃ and the drying time is 5~7h.

3. The method for preparing a self-supporting heterostructure electrocatalytic oxygen evolution electrode according to claim 1, characterized in that, In step 1, the thickness of the nickel foam is 0.5~1mm, the pore density is 100~130PPI, and the pore size is 0.1~0.3mm.

4. The method for preparing a self-supporting heterostructure electrocatalytic oxygen evolution electrode according to claim 1, characterized in that, In step 2, the volume ratio of the mixed solution of ethylene glycol and deionized water is 1:4 to 1:5, the ultrasonic treatment time is 15 to 25 minutes, the hydrothermal reaction temperature is 160 to 170°C, the reaction time is 5 to 6 hours, the drying temperature is 50 to 70°C, and the drying time is 7 to 9 hours.

5. The method for preparing a self-supporting heterostructure electrocatalytic oxygen evolution electrode according to claim 1, characterized in that, In step 2, the sulfur source is thiourea, and the molar ratio of the sulfur source to the nickel foam is 1:1 to 1:1.

5.

6. The method for preparing a self-supporting heterostructure electrocatalytic oxygen evolution electrode according to claim 1, characterized in that, In step 3, the molybdenum source is sodium molybdate dihydrate, the iron source is ferrous chloride tetrahydrate, and the sulfur source is thiourea; the molar ratio of the molybdenum source, iron source, and sulfur source is 1:1.5:3.5 to 1:2:4, the volume ratio of the mixed solution of ethylene glycol and deionized water is 1:4 to 1:5, the ultrasonic treatment time is 15 to 25 min, the hydrothermal reaction temperature is 160 to 180 °C, the reaction time is 10 to 11 h, the drying temperature is 50 to 70 °C, and the drying time is 7 to 9 h.

7. The method for preparing a self-supporting heterostructure electrocatalytic oxygen evolution electrode according to claim 1, characterized in that, In steps 2 and 3, after the hydrothermal reaction is completed, the mixture is rinsed 2-3 times with anhydrous ethanol and deionized water.

8. A hydrogen evolution electrode, characterized in that, The self-supporting heterostructure electrocatalytic oxygen evolution electrode was prepared using any one of claims 1 to 7.

9. An electrode material for an oxygen evolution battery, characterized in that, The electrode material is made of the hydrogen evolution electrode as described in claim 8.

10. The application of the oxygen evolution electrode as described in claim 8 in the electrocatalytic oxygen evolution reaction.

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