CN116024583A - Nickel sulfide nano rod array electrocatalytic material and preparation method and application thereof - Google Patents

Abstract

The invention discloses a nickel sulfide nano rod array electrocatalytic material, a preparation method and application thereof. The nickel sulfide nano rod array electrocatalytic material comprises a nickel-based material and Ni positioned on the nickel-based material ₃ S ₂ A material, wherein the Ni ₃ S ₂ The material is in the shape of a nano rod array with a rough surface, and the nano rod consists of nano particles. The preparation method comprises the following steps: providing an acid-washed nickel-based material and an aqueous solution comprising a nickel source and a sulfur source; and adding the pickled foam nickel material into the aqueous solution to perform a hydrothermal reaction, so as to obtain the nickel sulfide nanorod electrocatalytic material. The nickel sulfide nano rod array electrocatalytic material has excellent HER and OER catalytic activity and stability in alkaline solution, and can be used as an electrode for electrolysis of water anionsIn the polar hydrogen evolution reaction and the anodic oxygen evolution reaction.

Description

Nickel sulfide nanorod array electrocatalytic material and its preparation method and application

technical field

The invention belongs to the field of electrocatalytic materials, and in particular relates to a nickel sulfide nanorod array electrocatalytic material and a preparation method and application thereof.

Background technique

The rapid growth of population and the rapid development of industrial economy make people face unprecedented problems such as energy shortage and environmental degradation. The security of future energy has been widely concerned by people. As a sustainable energy source, hydrogen energy has the advantages of high energy density and zero pollution, and is currently considered to be one of the most promising energy carriers. Electrocatalytic water splitting is one of the most effective hydrogen production technologies, which has the advantages of green and pollution-free, simple equipment, and high product purity. To reduce the large energy consumption during water electrolysis, electrochemical catalysts are required to reduce the overpotentials of the hydrogen evolution reaction (HER) at the cathode and the oxygen evolution reaction (OER) at the anode, respectively. Noble metals such as Pt and Ru/Ir oxides are currently the most effective electrocatalysts for HER and OER, respectively, but their scarce reserves and high cost are not conducive to large-scale applications. Therefore, there is an urgent need to design and develop low-cost catalysts for HER and OER with excellent catalytic performance and stability.

In the past few years, researchers have devoted considerable effort to achieve these goals and found some very promising non-noble metal electrocatalysts, such as transition metal sulfides, selenides, carbides, phosphides, nitrides As well as alloys, etc. have been proven to have good HER catalytic performance. Transition metal oxides and hydroxides are currently the most studied non-noble metal OER catalysts. However, in contrast, there are relatively few studies on bifunctional electrocatalysts with both HER and OER activities. The reason is that most transition metal-based catalysts can only have good single catalytic activity and stability in acidic or alkaline solutions. For example, transition metal oxides/hydroxides have excellent OER catalytic performance, but due to their inappropriate crystal form or poor conductivity, their HER performance is generally poor, and they often do not have both HER and OER catalytic activities in the same electrolyte. , so its application in complete water splitting is limited. If different catalysts are used as HER and OER electrodes respectively, many technical problems will also arise in practical applications. In addition, since most OER catalysts are unstable in acidic media, they can only function in alkaline media, and the electrolysis of water under acidic conditions requires high electrolysis equipment materials, making it difficult to apply continuously on a large scale. Electrolyzed water has a broader application prospect in the market. Therefore, the development of bifunctional non-precious metal catalysts for HER and OER under alkaline conditions can more effectively improve the efficiency of complete water splitting and simplify the electrolysis system to facilitate industrial applications.

Among many transition metal compounds, nickel-based sulfides (such as NiS, _NiS2 and _{Ni3S2 ,} etc.) are widely used in energy storage fields such as supercapacitors, batteries and photo/electrocatalysis. Ni ₃ S ₂ has good and stable HER or OER catalytic performance, but there are still few research reports on Ni ₃ S ₂ with both HER and OER catalytic performance. Ni ₃ S ₂ is a nickelite ore with a rhombohedral structure and intrinsic metallic properties. Its Ni-Ni short bond is equivalent to that in metallic nickel, and all Ni atoms are connected along highly branched bonding paths to form a cross-linked network structure, which is conducive to electron transport. Good conductivity and low cost make Ni ₃ S ₂ have many applications in the field of electrochemistry. However, due to the low utilization of active sites, its catalytic performance is still much lower than that of Pt and Ru/Ir oxides, which is also a common problem with other transition metal compounds.

At present, there have been several effective methods to solve these problems, one of which is to construct various nanostructures, such as nanowires, nanospheres, nanotubes and nanosheets, etc. The materials of these nanostructures have greater activity ratio Surface area and higher catalytic hydrolysis efficiency. Another approach is to combine _Ni3S2 with high-conductivity materials to form composite nanostructures and improve _their electrical conductivity, thereby promoting electronic charge transfer during electrocatalysis and accelerating water splitting efficiency.

Contents of the invention

In order to solve the above-mentioned technical problems, the present invention provides a nickel sulfide nanorod array electrocatalytic material and its preparation method and application. The material has excellent catalytic activity and stability for HER and OER in alkaline solution: the catalyst obtained in the present invention The material only needs an overpotential of 120mV in 1.0M KOH solution to drive a current density of 10mA cm ^-2 , which is superior to existing HER catalysts; at the same time, it shows very good OER catalytic performance in alkaline electrolyte, Only an overpotential of 270 mV is required to achieve a current density of 10 mA cm ^-2 . It can be used as an electrode in the cathodic hydrogen evolution reaction and anode oxygen evolution reaction of electrolyzed water.

The present invention firstly provides a nickel sulfide nanorod array electrocatalytic material, comprising: a nickel-based material and a Ni ₃ S ₂ material located on the nickel-based material, wherein:

Described nickel-based material is nickel foam (Ni foam, NF) with three-dimensional porous structure, and this material is a kind of low-cost and has the metallic conductive material of high specific surface area, is very suitable for supporting catalyst and increases electrochemical active site; Furthermore, the direct growth of active materials on nickel foam enhances the catalyst-substrate contact, leading to efficient electron transport during the water splitting reaction.

The Ni ₃ S ₂ material is evenly and densely distributed on the nickel foam. The Ni ₃ S ₂ material is distributed in a nano-cone shape on the nickel foam and has a smooth surface; or the Ni ₃ S ₂ material is a nano-rod array with a rough surface, and the nano-rod array is composed of nanoparticles , the nanoparticles are tightly stacked; or the small particles on the Ni ₃ S ₂ material nanorods grow up and adhere to fuse into large particles.

The present invention also provides a method for preparing the aforementioned nickel sulfide nanorod array electrocatalytic material, comprising:

Step S1: provide the pickled nickel-based material and an aqueous solution including a nickel source and a sulfur source; step S2: add the pickled nickel-based material to the aqueous solution for hydrothermal reaction to obtain nickel sulfide nanorod array electrocatalysis Material.

Optionally, the nickel source includes Ni(NO ₃ ) ₂ ·6H ₂ O, and the sulfur source includes Na ₂ S ₂ O ₃ .

Optionally, the molar ratio of the nickel source to the sulfur source is (1-2):(4-8). More preferably, the molar ratio of the nickel source to the sulfur source is 1:4.

Optionally, in step S1, the method for pickling the nickel-based material includes: placing the nickel-based material in a hydrochloric acid solution and ultrasonically for 15 minutes; placing the pickled nickel-based material in absolute ethanol and washing in deionized water; washing the nickel-based material with water and then drying.

Optionally, in step S2, the temperature of the hydrothermal reaction is 80-130° C., and the reaction time is 1-6 hours. More preferably, the temperature of the hydrothermal reaction is 120° C., and the reaction time is 3 hours.

Optionally, in step S2, washing and drying are performed after the hydrothermal reaction, and the washing and drying method includes: repeatedly washing with water and ethanol for 3 to 5 times, and drying at 50 to 70°C for 12 to 24 Hour.

The present invention also provides the application of the nickel sulfide nanorod array electrocatalytic material as an electrode in the cathode hydrogen evolution reaction and the anode oxygen evolution reaction of electrolyzed water.

Compared with the prior art, the nickel sulfide nanorod array electrocatalytic material and its preparation method of the technical solution of the present invention have the following beneficial effects:

The invention selects nickel-based materials as the substrate, and the raw materials used are rich in sources and low in cost. Through a simple one-step hydrothermal method, nickel sulfide nanorods composed of nanoparticles are directly grown on the three-dimensional porous nickel foam. The preparation method is simple, the conditions are mild, and the production cost can be reduced.

The nickel sulfide nanorod array electrocatalytic material prepared by the present invention has high activity and excellent stability in the electrolytic water HER and OER catalytic reactions, which are mainly attributed to: on the one hand, the nanorod morphology composed of nanoparticles provides Large electrochemically active surface area. On the other hand, the direct coupling of Ni ₃ S ₂ and nickel foam reduces the resistance between the active material and the substrate, providing a fast interconnected channel for charge transport.

The nickel sulfide nanorod array electrocatalytic material prepared in the present invention is a flexible self-supporting electrode without a binder, and has excellent activity and stability in HER and OER catalytic reactions of electrolyzed water. Experiments have proved that the catalyst material obtained in the present invention only needs an overpotential of 120mV in a 1.0M KOH solution to drive a current density of 10mA cm ^-2 , which is superior to existing HER catalysts; Very good OER catalytic performance, only 270mV overpotential can reach a current density of 10mA cm ^-2 . All in all, NiS nanorod array electrocatalytic materials have excellent catalytic performance for HER and OER in alkaline media, and have great application prospects in total water splitting.

Description of drawings

Fig. 1 is the XRD pattern of Ni ₃ S ₂ /NF prepared in Example 1-3 of the present invention;

Fig. 2 is the SEM image of Ni ₃ S ₂ /NF prepared in Example 1-3 of the present invention;

Fig. 3 is the hydrogen evolution reaction (HER) polarization curve (LSV) diagram and electrochemical impedance spectrum diagram of Ni ₃ S ₂ /NF prepared in Examples 1-3 of the present invention and the electrocatalyst material prepared in Comparative Example 1;

Figure 4 is a comparison of the electrocatalytic stability curve of Ni ₃ S ₂ /NF prepared in Example 1 of the present invention and the LSV polarization curve before and after continuous electrolysis for 14 hours;

Figure 5 is the LSV diagram of the oxygen evolution reaction (OER) of Ni ₃ S ₂ /NF prepared in Example 1 of the present invention in an oxygen-saturated 1.0M potassium hydroxide solution, the OER electrocatalytic stability curve and the 15-hour continuous electrolysis Comparison of LSV polarization curves.

Detailed ways

In view of this, the technical scheme of the present invention provides a nickel sulfide nanorod array electrocatalytic material and its preparation method and application. The nickel sulfide nanorod array electrocatalytic material is synthesized on the substrate by a hydrothermal method on the pickled foamed nickel material. Catalytic material, the nickel sulfide nanorod array electrocatalytic material has excellent HER and OER catalytic activity and stability in alkaline solution.

In order to enable those skilled in the art to better understand the technical solutions in the present invention, the present invention will be further described below in conjunction with the following examples. Obviously, the described examples are only some examples of the present invention, rather than all Example. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

An embodiment of the present invention provides a method for preparing a nickel sulfide nanorod array electrocatalytic material, comprising:

Step S1: provide the nickel-based material after pickling and the aqueous solution comprising nickel source and sulfur source;

Step S2: adding the pickled nickel-based material into the aqueous solution for hydrothermal reaction to obtain nickel sulfide nanorod array electrocatalytic material.

In step S1, the pickled nickel-based material is provided. The purpose of pickling is to remove the oxide layer on the surface of nickel-based materials. The method for pickling the nickel-based material may include:

Step S11: cleaning the nickel-based material in hydrochloric acid solution, and then in absolute ethanol and water for cleaning. The cleaning method can be ultrasonic cleaning, and the cleaning time can be determined according to the actual situation. In some embodiments, ultrasonic cleaning may be used for 15 minutes.

Step S12: washing the nickel-based material with water and then drying it. After the nickel-based material was rinsed with deionized water, it was dried in an oven at 60° C. for 12 hours.

The nickel source includes Ni(NO ₃ ) ₂ ·6H ₂ O, and the sulfur source includes Na ₂ S ₂ O ₃ . In the embodiment of the present invention, the molar ratio of the nickel source and the sulfur source is (1-2):(4-8). Add nickel source and sulfur source into deionized water, stir and dissolve to obtain a uniform aqueous solution.

The pickled nickel-based material is added into the aqueous solution for hydrothermal reaction. In some embodiments, the nickel-based material after pickling can be placed in the aqueous solution, and then transferred to a hydrothermal reaction tank for hydrothermal reaction after being fully wetted. The volume of the aqueous solution is 70%-80% of the polytetrafluoroethylene lining, and the aqueous solution needs to be submerged in the nickel-based material. The temperature of the hydrothermal reaction may be 80-130° C., and the reaction time may be 1-6 hours. After the hydrothermal reaction is finished, the substrate is taken out for washing and drying to obtain a nickel sulfide nanorod array product. When washing and drying, rinse repeatedly with water and ethanol for 3-5 times, and dry at 50-70°C for 12-24 hours.

Embodiments of the present invention also provide a nickel sulfide nanorod array electrocatalytic material, including a nickel-based material and a Ni ₃ S ₂ material positioned on the nickel-based material, wherein the nickel-based material can be a nickel foam substrate (NF) , the Ni ₃ S ₂ material is a nano-rod array with a rough surface, and the nano-rods are stacked by nano-particles, arranged tightly and orderly on the nickel-based material.

In the embodiment of the present invention, a Ni ₃ S ₂ /NF nanorod array is grown on a nickel-based material by a simple one-step hydrothermal method. Firstly, the pickling pretreatment of the nickel-based material can remove the surface oxide layer, which is conducive to the uniform growth of the product on the nickel-based material. After one-step hydrothermal reaction, dense and uniform arrays of nickel sulfide nanorods were obtained.

When the nickel sulfide nanorod array electrocatalytic material of the embodiment of the present invention is used for electrocatalysis in the cathode hydrogen evolution reaction and the anode oxygen evolution reaction of electrolyzed water, it has high activity and good stability.

Example 1

A preparation method of nickel sulfide nanorod array electrocatalytic material, comprising:

(1) The nickel foam is subjected to pickling pretreatment. The nickel foam was placed in hydrochloric acid, absolute ethanol and deionized water in sequence for ultrasonic cleaning for 15 minutes respectively. The pretreated carbon cloth was rinsed with deionized water and dried in an oven at 60°C for 12 hours.

(2) Dissolve 1 mmol Ni(NO ₃ ) ₂ ·6H ₂ O and 4 mmol Na ₂ S ₂ O ₃ in 20 mL deionized water, and stir magnetically for 20 minutes to form a uniform solution. Then, cut a piece of pretreated nickel foam (2cm×2cm) into the solution, transfer it to a 50mL hydrothermal reactor after fully wetting, and react at 120°C for 3 hours. Finally, the obtained product was repeatedly washed with deionized water and ethanol for 3 to 5 times, and dried in an oven at 60° C. for 12 hours to obtain the nickel sulfide nanorod array electrocatalytic material.

Example 2

A preparation method of nickel sulfide nanorod array array electrocatalytic material, comprising:

(1) With step (1) in embodiment 1.

(2) With the step (2) in the embodiment 1, but the reaction time is 1 hour.

Example 3

A nickel sulfide nanorod array electrocatalytic material, comprising the following steps:

(1) With step (1) in embodiment 1.

(2) With the step (2) in the embodiment 1, but the reaction time is 6 hours.

Example 4

A nickel sulfide nanorod array electrocatalytic material, comprising the following steps:

(1) With step (1) in embodiment 1.

(2) Same as step (2) in Example 1, but the dosages of Ni(NO ₃ ) ₂ ·6H ₂ O and Na ₂ S ₂ O ₃ are 0.5 mmol and 4 mmol, respectively.

Example 5

A nickel sulfide nanorod array electrocatalytic material, comprising the following steps:

(1) With step (1) in embodiment 1.

(2) Same as step (2) in Example 1, but the dosages of Ni(NO ₃ ) ₂ ·6H ₂ O and Na ₂ S ₂ O ₃ are 1.5 mmol and 3 mmol, respectively.

Example 6

A nickel sulfide nanorod array electrocatalytic material, comprising the following steps:

(1) With step (1) in embodiment 1.

(2) With step (2) in embodiment 1, but reaction temperature is 80 ℃.

Example 7

A nickel sulfide nanorod array electrocatalytic material, comprising the following steps:

(1) With step (1) in embodiment 1.

(2) With step (2) in embodiment 1, but reaction temperature is 130 ℃.

Comparative example 1

In this comparative example, nickel foam (NF) after pickling pretreatment was directly used as the electrocatalyst for HER and OER. The pickling pretreatment process is the same as step (1) in Example 1.

Comparative example 2

A kind of amorphous nickel sulfide electrocatalytic material, comprises steps as follows:

(1) With step (1) in embodiment 1.

(2) With step (2) in embodiment 1, but reaction temperature is 85 ℃.

The XRD spectrum of Ni ₃ S ₂ /NF prepared in Examples 1-3 is shown in FIG. 1 . As shown in the figure, obvious metallic nickel peaks can be observed in the three samples, which are located at 2θ=44.5°, 51.7°, and 76.3° respectively, which belong to the base foam nickel (PDFNO.04-0850). In addition to the characteristic diffraction peaks _of metallic nickel, characteristic peaks belonging to the heazlewoodite type _Ni3S2 can also be observed. When the reaction time was 1 h, only an extremely weak Ni ₃ S ₂ peak was observed in the spectrum of the sample of Example 2, indicating that the crystallization of Ni ₃ S ₂ was not complete at this time. After extending the reaction time to 3h, it can be clearly observed from the XRD spectrum of the sample of Example 1 that the characteristic peaks belonging to Ni ₃ S ₂ are at 2θ=31.2°, 37.9°, 38.4°, 49.8° and 55.0° The diffraction peaks correspond to (110), (003), (021), (113) and (122) crystal planes of Ni ₃ S ₂ (PDF NO.44-1418), respectively. These characteristic peaks are narrow and sharp, indicating that the crystallinity of the sample is very good at this time, which is conducive to improving its electrical conductivity. When reacted to 6h, Example 3 still has the characteristic peak of Ni ₃ S ₂ , but the crystallinity decreases instead.

Fig. 2 is the SEM image of samples of different embodiments. By a simple one-step hydrothermal method, Ni ₃ S ₂ is uniformly and densely distributed on the nickel foam, and it can be observed that the morphology of Ni ₃ S ₂ changes significantly with the prolongation of the reaction time. As shown in Figure 2a and b, when the reaction time is 1 h, Ni ₃ S ₂ is distributed on the nickel foam in a nano-cone shape, the shape is like mushrooming mushrooms, and the surface is very smooth. When reacting for 3 h, it can be seen from Figure 2c and d that the smooth nanocones transformed into nanopillars stacked by many nanoparticles. These nanoparticles are densely packed with uneven surface, have more abundant voids and larger specific surface area than smooth nanocones, which can provide abundant active sites. Continue to prolong the reaction time to 6h, it can be found that the small particles on the above-mentioned nanopillars gradually grow up and stick together, and finally fuse into large particles (Figure 2e and f), which will reduce the specific surface area of the material and lead to the reduction of catalytic active sites. From the SEM images and XRD images during the growth process of Ni ₃ S ₂ /NF, we can see that the reaction time is different, and the morphology and crystal structure of the obtained products are also different. Therefore, we can control the morphology and structure of the product by adjusting the reaction time to obtain samples with different properties.

The above test results all show that the embodiment of the present invention successfully synthesized nickel sulfide nanorod arrays.

The products obtained in Example 1-3 and Comparative Example 1-2 were scanned in 1.0M potassium hydroxide solution at a scan rate of 5mV/s at 25°C, and the LSV polarization curve of HER was obtained, as shown in Figure 3 . The electrocatalytic stability of Ni ₃ S ₂ /NF obtained in Example 1 was evaluated by continuous electrolysis at a constant voltage of -1.27V, and the results are shown in FIG. 4 . The LSV polarization curve and electrocatalytic stability curve of the OER of the product obtained in Example 1 in 1.0M potassium hydroxide solution are shown in Figure 5

With reference to Fig. 3, wherein a graph is the LSV polarization curve of the HER of embodiment 1-3 and comparative example 1-2, b graph is embodiment 1-3 and comparative example 2 at the current density of 10 and 50mA cm ^-2 of overpotential. Figure C is the Tafel curve, and Figure d is the Nyquist curve (η=293mV). It can be seen from Figure a that the HER catalytic activity of Comparative Example 1 is very poor, and η ₁₀ is 268mV. On the contrary, the example sample shows excellent catalytic performance, indicating that the HER catalytic performance of the material is mainly contributed by the catalyst. Among the series of nickel sulfide samples prepared, Example 1 has the best HER catalytic activity, and the current increases rapidly with the increase of voltage. When the current density is 10, 20 and 50mA cm ^-2 , the overpotentials are respectively 120, 159 and 238mV. Figure 3b lists the overpotentials of Examples 1-3 and Comparative Examples 1-2 at current densities of 10 and 50mA cm ^-2 . It can be seen that among these samples, Example 1 has the lowest overpotential and the best HER catalytic performance . This is mainly due to the unique nano-morphology and good crystallinity of Example 1: the nano-rod shape formed by stacking nanoparticles has a larger specific surface area, and good crystallinity can also provide more active sites on the crystal face dots and high electrical conductivity, thus facilitating the HER catalytic process. As shown in Figure 3c, the Tafel slopes of Examples 1, 2 and 3 are 80, 87 and 85mV dec ^-1 , respectively, while the Tafel slope of Comparative Example 1 is 120mV dec ^-1 . In contrast, the smaller Tafel slope of Example 1 shows that it has a faster kinetic reaction rate during the reaction process, and as the overpotential increases, the hydrogen evolution reaction rate accelerates rapidly. Analyzing the electrochemical impedance diagram again, it can be clearly seen that the charge transfer resistance of Example 1 is the smallest, which is much smaller than that of the other three samples, indicating that Example 1 has faster charge transfer in the HER catalytic process, and the surface electron transport ability is enhanced. Thanks to its good crystallinity and intrinsic metallic properties of nickelite-type Ni ₃ S ₂ , the network structure formed by the interconnection of Ni—Ni metal bonds is beneficial to electron transport.

Referring to Figure 4, after 1000 cycles of CV cycles, the LSV polarization curve of the sample basically coincides with the curve before the test, indicating that its HER catalytic performance has almost no attenuation. To test its durability in the catalytic process, a current-time method was used to continuously catalyze the electrolysis in 1.0 M KOH for 14 h at a fixed overpotential of 127 mV. The obtained i–t curves are shown in Fig. 4b. During the continuous electrolysis process, the HER catalytic current has been kept stable with almost no attenuation. In addition, it can be seen from the inset that the LSV polarization curves after electrolysis for 14 h are almost completely coincident with those before the test. These results collectively indicate that the prepared electrode material of Example 1 has excellent electrocatalytic stability and has great potential in practical applications.

The above electrochemical test results all show that the Ni ₃ S ₂ /NF prepared in Example 1 has excellent HER electrocatalytic performance and electrocatalytic stability in the process of alkaline electrolysis of water.

Referring to Figure 5, the OER electrocatalytic performance of the material was further tested, and the electrochemical test results showed that Example 1 also had excellent OER catalytic activity in alkaline media. As shown in Fig. 5, the OER activity of the base nickel foam is very poor, almost negligible. However, the performance of the sample in Example 1 has been greatly improved, and the current density of 10 mA cm ⁻² can be achieved only with an overpotential of 270 mV. In addition, at the current density of 50 and 100 mA cm ^-2 , the overpotentials of Example 1 are 310 and 340 mV, respectively, even much lower than RuO ₂ (η50 = 388 mV). In the long-term OER catalytic stability test, Example 1 also showed good stability. It can be seen from Figure 5b that the catalytic performance of the material decreases slightly during the first 8 h of electrolysis, while the current density remains basically constant during the subsequent electrolysis. The above results indicate that Ni ₃ S ₂ /NF has excellent electrocatalytic activity for OER and good electrocatalytic stability.

Although the present invention has been disclosed as above with a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can use the methods and technical contents disclosed above to analyze the present invention without departing from the spirit and scope of the present invention. Therefore, any simple modification, equivalent change and modification made to the above implementation methods according to the technical essence of the present invention, which do not depart from the content of the technical solution of the present invention, all belong to the technical solution of the present invention. protected range.

Claims (13)

1. A nickel sulfide nanorod array electrocatalytic material, comprising: nickel-based material and Ni on the nickel-based material ₃ S ₂ A material, wherein the nickel-based material is a porous three-dimensional junctionStructural foam nickel, said Ni ₃ S ₂ The material is uniformly and densely distributed on the foam nickel.

2. The nickel sulfide nanorod array electrocatalytic material according to claim 1, wherein the Ni ₃ S ₂ The material is distributed on the foam nickel in a nano cone shape, and the surface is smooth; or Ni ₃ S ₂ The material is in the shape of a nano rod array with a rough surface, the nano rod array consists of nano particles, and the nano particles are tightly stacked; or Ni ₃ S ₂ The small particles on the material nano rod grow up and are adhered and fused into large particles.

3. The nickel sulfide nanorod array electrocatalytic material of claim 1, wherein the nickel sulfide nanorod array electrocatalytic material has HER catalytic activity and stability in alkaline solution: can drive 10mA cm under 120mV overpotential ^-2 Is used for the current density of the battery.

4. The nickel sulfide nanorod array electrocatalytic material of claim 1, wherein the nickel sulfide nanorod array electrocatalytic material has OER catalytic activity and stability in alkaline solution: can reach 10mA cm at 270mV overpotential ^-2 Is used for the current density of the battery.

5. A method for preparing the nickel sulfide nanorod array electrocatalytic material according to claim 1, comprising:

step S1: providing an acid-washed nickel-based material and an aqueous solution comprising a nickel source and a sulfur source;

step S2: and adding the nickel-based material subjected to acid washing into the aqueous solution to perform hydrothermal reaction to obtain the nickel sulfide nanorod array electrocatalytic material.

6. The method for preparing a nickel sulfide nanorod array electrocatalytic material according to claim 5, wherein the nickel-based material is foam nickel with a three-dimensional porous structure, and the nickel source isIs Ni (NO) ₃ ) ₂ ·6H ₂ O, the sulfur source is Na ₂ S ₂ O ₃ 。

7. The method for preparing the nickel sulfide nanorod array electrocatalytic material according to claim 5, wherein the molar ratio of the nickel source to the sulfur source is (1-2): (4-8).

8. The method for preparing the nickel sulfide nanorod array electrocatalytic material according to claim 7, wherein the molar ratio of the nickel source to the sulfur source is 1:4.

9. The method for preparing the nickel sulfide nanorod array electrocatalytic material according to claim 5, wherein the method for pickling the nickel-based material in the step S1 comprises the following steps:

placing the nickel-based material in hydrochloric acid solution for ultrasonic treatment for 15min;

sequentially placing the nickel-based material subjected to acid washing in absolute ethyl alcohol and deionized water for cleaning;

and cleaning the nickel-based material with water and drying.

10. The method for preparing an electrocatalytic material of a nickel sulfide nano rod array as set forth in claim 5, wherein the hydrothermal reaction in the step S2 is performed at a temperature of 80-130 ℃ for 1-6 hours.

11. The method for preparing an electrocatalytic material of a nickel sulfide nanorod array according to claim 10, wherein the hydrothermal reaction in the step S2 is performed at 120 ℃ for 3 hours.

12. The method for preparing the nickel sulfide nanorod array electrocatalytic material according to claim 5, wherein in the step S2, washing and drying are performed after the hydrothermal reaction, and the washing and drying method comprises the following steps: repeatedly washing with water and ethanol, and drying at 50-70 ℃ for 12-24 hours.

13. The use of the nickel sulfide nanorod array electrocatalytic material according to claim 1, wherein the electrocatalytic material can be used as an electrode in an electrolyzed water cathodic hydrogen evolution reaction and an anodic oxygen evolution reaction.

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