NiSe2 / CoSe / NF nanomaterials with basic nickel-cobalt carbonate as precursors, their preparation methods and applications

Abstract

The application provides a NiSe2 / CoSe / NF nanomaterial taking basic nickel cobalt carbonate as a precursor and a preparation method and application thereof.The nanomaterial is a NiSe2 / CoSe heterostructure nanomaterial loaded on a foam nickel surface.The nanomaterial has multiple functions, has both photocatalytic degradation performance and electrocatalytic hydrogen production performance, and exhibits excellent HER and OER bifunctional catalytic activity under alkaline conditions, while being capable of effectively degrading organic pollutants in sewage.The catalyst can be applied not only to water electrolysis, but also to degradation of organic pollutants in sewage, and then to hydrogen production by electrolysis of the treated sewage, so that the catalyst realizes multiple functions and realizes resource utilization of sewage, can solve the sewage treatment problem, reduces resource waste, realizes sustainable development, and has a good application prospect.

Description

Technical Field

[0001] This invention relates to a NiSe2 / CoSe / NF nanomaterial with basic nickel cobalt carbonate as a precursor, its preparation method and application, belonging to the field of photo / electrocatalysis. Background Technology

[0002] With rapid industrialization, energy crises and environmental pollution have become global problems facing human society, and water pollution also threatens environmentally friendly development and human health. Electrolysis of water to produce hydrogen is a method that uses renewable energy sources (such as solar or wind power) to generate electricity and then produces hydrogen through an electrolysis process. It is clean, renewable, and safe. Hydrogen energy is an important component of clean energy and is hailed as the "ultimate energy of the 21st century," effectively alleviating the energy crisis. Utilizing semiconductor photocatalysis technology to degrade harmful organic matter in polluted water has become a new environmental remediation method. Due to its high efficiency, low toxicity, and stability during the degradation process, this technology has shown broad application prospects in the field of environmental governance. Therefore, the research on bifunctional semiconductor catalysts that possess both the ability to produce hydrogen through water electrolysis and the ability to degrade pollutants in water has become a focus of attention for many researchers.

[0003] Metal basic carbonates are often widely studied as high-performance materials due to their advantages such as high redox activity, variable metal oxidation states, tunable structure, simple synthesis, and relatively low cost (see: Journal of Colloid and Interface Science 621(2022)149-159). Chinese patent document CN 113604830 A discloses a method for hydrothermally growing basic nickel-cobalt carbonate nanowire precursors on a micron-sized porous carbon fiber matrix, using hydrazine hydrate as a reducing agent, and obtaining a CoSe2 / NiSe2 / CFs electrocatalyst with single electrocatalytic hydrogen evolution (HER) performance via hydrothermal selenization. Chinese patent document CN 115976556 A discloses a CoSe2 / NiSe2 composite nano-heterostructure electrocatalyst material with single electrochemical oxygen evolution (OER) performance, at a current density of 10 mA / cm². -2 At that time, the overpotential reached 395mV, and the flammable liquid dimethyl sulfoxide (DMSO), which has a certain degree of toxicity, was also used in the preparation process.

[0004] In today's high-tech industries, finding materials with unique properties is key to continuous innovation and efficiency improvement. Among them, nickel foam (NF) has become a representative of the new generation of high-efficiency materials due to its unique properties and wide range of applications. Nickel foam is a special metallic material with a large number of voids in its microstructure, which resemble foam, hence the name nickel foam. This special structure endows nickel foam with some unique properties. The high specific surface area and open-cell structure of nickel foam effectively accelerate mass transfer and gas release (see: Applied Catalysis B: Environmental 323 (2023) 122091). Therefore, constructing nanostructures on nickel foam is an effective strategy for preparing high-efficiency catalysts. Moreover, compared with carbon substrates such as carbon cloth and carbon paper, nickel foam has superior conductivity, stability under alkaline conditions, and an open-cell structure suitable for bubble separation (see: Nano Res. 11 (2018) 3959-3971). Chinese patent document CN 113957468 A discloses a Ni3S2@CoO-NF composite material with hydrogen evolution properties, which is effective when the current density is 10 mA / cm². -2 At that time, the overpotential reached 180mV, and the function was singular. Chinese patent document CN 116889873 A discloses a photocatalyst for degrading Rhodamine B using nickel foam-supported Fe@Fe2O3, but the degradation rate of Rhodamine B was only 73.2%. Moreover, the preparation process used flammable, explosive, and extremely harmful sodium borohydride as a reducing agent, and the material did not exhibit electrocatalytic performance. Chinese patent document CN 114411189A discloses a method for preparing a CoSe-modified layered bimetallic hydroxide catalyst. First, a layer of Co precursor is modified onto the layered bimetallic hydroxide through a two-step hydrothermal method, and then a single-function electrocatalyst with only oxygen evolution performance is synthesized through selenization calcination.

[0005] Therefore, researching a multifunctional catalyst with electrocatalytic hydrogen evolution, oxygen evolution, and photocatalytic degradation of organic pollutants has potential application value in the fields of hydrogen energy development and environmental protection. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a NiSe2 / CoSe / NF nanomaterial with basic nickel-cobalt carbonate as a precursor, along with its preparation method and applications. The catalyst preparation method of this invention is simple, efficient, safe, and inexpensive. The prepared catalyst exhibits diverse functions, possessing both photocatalytic degradation and electrocatalytic hydrogen production capabilities. Under alkaline conditions, it demonstrates excellent bifunctional HER and OER catalytic activity, while effectively degrading organic pollutants in wastewater. This catalyst can be applied not only to water electrolysis but also to the degradation of organic pollutants in wastewater, followed by further electrolysis of the treated wastewater to produce hydrogen. This single catalyst achieves multiple functions, realizing the resource utilization of wastewater. It not only solves wastewater treatment problems but also reduces resource waste, achieving sustainable development and demonstrating promising application prospects, providing strong support for ensuring high-quality regional economic development.

[0007] The technical solution of the present invention is as follows:

[0008] A NiSe2 / CoSe / NF nanomaterial using basic nickel-cobalt carbonate as a precursor, wherein the NiSe2 / CoSe / NF nanomaterial is a NiSe2 / CoSe heterostructure nanomaterial supported on a nickel foam surface; the microstructure of the NiSe2 / CoSe / NF nanomaterial is a three-dimensional multi-level nanostructure assembled from zero-dimensional nanoparticles, one-dimensional nanowires, and two-dimensional nanosheets; wherein the two-dimensional nanosheets are woven from one-dimensional nanowires, the surface of which is loaded with spherical zero-dimensional nanoparticles, and the two-dimensional nanosheets further self-assemble into a multi-level nanoflower-like structure; or, the microstructure of the NiSe2 / CoSe / NF nanomaterial is a sea urchin-like structure assembled from zero-dimensional nanoparticles and one-dimensional nanowires, the surface of which is loaded with spherical zero-dimensional nanoparticles.

[0009] The preparation method of the above-mentioned NiSe2 / CoSe / NF nanomaterials using basic nickel-cobalt carbonate as a precursor includes the following steps:

[0010] (1) Cobalt nitrate hexahydrate, nickel nitrate hexahydrate, urea and ammonium fluoride were dissolved in ultrapure water, and pretreated foamed nickel was added. The mixture was then subjected to a hydrothermal reaction. The precursor of basic nickel cobalt carbonate was obtained by separation, washing and drying.

[0011] (2) The basic nickel-cobalt carbonate precursor and selenium powder were placed at both ends of a ceramic boat and covered. The selenium powder was placed near the inlet of the protective gas of the tube furnace, and the basic nickel-cobalt carbonate precursor was placed near the outlet of the protective gas. NiSe2 / CoSe / NF nanomaterials were obtained by calcination under the protective gas atmosphere.

[0012] According to a preferred embodiment of the present invention, in step (1), the molar ratio of nickel nitrate hexahydrate, cobalt nitrate hexahydrate, urea and ammonium fluoride is 1:2:10:(0-5), preferably 1:2:10:(1.5-4.5).

[0013] According to a preferred embodiment of the present invention, in step (1), the molar ratio of cobalt nitrate hexahydrate to the volume ratio of ultrapure water is (0.1-1):15 mol / L. -1 .

[0014] According to a preferred embodiment of the present invention, step (1) of the method for preparing pretreated nickel foam includes the following steps: ultrasonically treating nickel foam in acetone, ethanol, and ultrapure water for 10-30 min respectively, followed by vacuum drying to obtain pretreated nickel foam. Preferably, the vacuum drying temperature is 50-70℃ and the vacuum drying time is 4-8 h.

[0015] According to the present invention, in step (1), the pretreated nickel foam is immersed in a mixture of cobalt nitrate hexahydrate, nickel nitrate hexahydrate, urea, ammonium fluoride, and ultrapure water; the molar ratio of cobalt nitrate hexahydrate to the area of ​​the nickel foam is 1:(0.1-1) mmol / cm². -2 The area of ​​the nickel foam refers to the area of ​​the largest surface of the nickel foam.

[0016] According to a preferred embodiment of the present invention, in step (1), the hydrothermal reaction temperature is 110-130°C and the hydrothermal reaction time is 4-8h.

[0017] According to a preferred embodiment of the present invention, in step (1), the drying is vacuum drying, the drying temperature is 40-80℃, and the drying time is 6-20h.

[0018] According to a preferred embodiment of the present invention, in step (2), the mass ratio of selenium powder to cobalt nitrate hexahydrate in step (1) is 1:(2-4), preferably 1:2.91.

[0019] According to a preferred embodiment of the present invention, in step (2), the protective gas is nitrogen or argon.

[0020] According to a preferred embodiment of the present invention, in step (2), after the basic nickel-cobalt carbonate precursor and selenium powder are placed into the tube furnace, the tube furnace is subjected to 2-4 vacuum treatments, and then a protective gas is introduced.

[0021] According to a preferred embodiment of the present invention, in step (2), during the calcination process, gas is continuously introduced into the tubular furnace, and the gas outlet of the tubular furnace is connected to the tail gas absorption liquid through a pipe. The rate of bubbles generated by the gas discharged from the pipe in the tail gas absorption liquid is (1-3) bubbles / s.

[0022] According to a preferred embodiment of the present invention, in step (2), the calcination conditions are: a heating rate of 1-5°C / min. -1The calcination temperature is 300-550℃, and the holding time is 0.5-4h.

[0023] The NiSe2 / CoSe / NF nanomaterials with basic nickel-cobalt carbonate as precursors are used as electrocatalysts in the hydrogen evolution reaction (HER) and / or oxygen evolution reaction (OER) of water electrolysis, and / or as photocatalysts for the degradation of organic dyes in wastewater.

[0024] According to a preferred embodiment of the present invention, the application method includes the following steps: using NiSe2 / CoSe / NF nanomaterials with basic nickel cobalt carbonate as a precursor as a photocatalyst to degrade organic dyes in wastewater, and then separating the wastewater to obtain treated wastewater; then using NiSe2 / CoSe / NF nanomaterials with basic nickel cobalt carbonate as a precursor as an electrocatalyst and the treated wastewater as an electrolyte to carry out electrocatalytic hydrogen evolution reaction (HER) and / or oxygen evolution reaction (OER).

[0025] According to a preferred embodiment of the present invention, the organic dye is Rhodiola B.

[0026] Technical features and beneficial effects of the present invention:

[0027] 1. The preparation process of this invention is simple, efficient, and safe, and the raw materials are inexpensive and readily available. The entire process uses only water as a solvent, making the reaction green and requiring no organic solvents, thus being economical and environmentally friendly. This invention uses selenium powder as the selenium source, which is safer than other selenium sources such as ammonium selenite and selenium dioxide.

[0028] 2. This invention utilizes nickel foam to prepare a basic nickel-cobalt carbonate precursor using a simple one-step hydrothermal method without the use of any binder, and then uses a calcination selenization method to obtain a catalyst with excellent hydrogen evolution and oxygen evolution dual functions; moreover, based on the bandgap engineering principle of semiconductor heterojunctions, under sunlight irradiation, NiSe2(E g =1.61eV) and CoSe(E g The narrow band gap (1.8 eV) allows electrons to be excited from the valence band to the conduction band, resulting in excellent photocatalytic degradation performance. The method of this invention also further solves the problem of catalyst detachment.

[0029] Transition metal selenides also possess high availability and conductivity, exhibiting significant bifunctional hydrogen evolution and oxygen evolution reaction performance; simultaneously, metal selenides are characterized by narrow band gaps and low internal resistance, making them promising photocatalysts; the heterojunction composed of the two selenides in this invention can greatly improve the performance of the catalyst.

[0030] In this invention, NH4F acts as an excellent morphology modifier, which can make the nanostructure more uniform, and the released F... -This can promote the formation of more active sites in nickel foam, which is beneficial for a closer interaction between the active sites and the nickel foam. - It plays a crucial role in the nucleation rate of basic nickel-cobalt carbonate precursors. By controlling the amount of NH4F, catalysts with different morphologies can be obtained, and the different morphologies can lead to differences in the performance of catalyst materials.

[0031] In the preparation method of this invention, the amount of ammonium fluoride is crucial. Adjusting the amount of ammonium fluoride added can yield target products with different morphologies and properties. For example, without adding ammonium fluoride, a sea urchin-like NiSe2 / CoSe / NF-0.0 is obtained, whose properties are significantly different from the NiSe2 / CoSe / NF-3.0 three-dimensional nanoflowers obtained when 3.0 mmol of ammonium fluoride is added. The preparation method of this invention, as a whole, requires the combined action of each step and condition to obtain the target product with the desired morphology, structure, and catalytic performance. Changing any condition or step will prevent the achievement of the excellent effects of this invention. For example, the ratio of nickel nitrate hexahydrate, cobalt nitrate hexahydrate, urea, and ammonium fluoride, the amount of selenium powder, and the calcination method and conditions. If the basic nickel-cobalt carbonate precursor and selenium powder are placed in two ceramic boats, the calcination reaction will be incomplete, and the desired substance will not be formed.

[0032] 3. The NiSe2 / CoSe / NF heterostructure nanomaterials prepared in this invention possess both electrocatalytic hydrogen production and photocatalytic degradation properties. When used as an electrocatalyst for water electrolysis, the material exhibits excellent bifunctional HER and OER catalytic activity, and can also serve as a photocatalyst for effectively degrading pollutants in wastewater. When used as an electrocatalyst for hydrogen production through water electrolysis, the material achieves a current density of 10 mA / cm² in a 1M KOH aqueous solution. -2 100mAcm -2 200mAcm -2 At that time, the overpotentials of HER were only 131mV, 231mV and 279mV, respectively; when the current density reached 10mAcm -2 50mAcm -2 100mAcm -2 At these times, the overpotentials of OER were only 167mV, 238mV, and 299mV, respectively, demonstrating excellent electrocatalytic hydrogen evolution and oxygen evolution performance. When the material of this invention is used as a photocatalyst to degrade Rhodamine B pollutant in wastewater, under continuous irradiation with an 800W xenon lamp for 140 min, the degradation rate of Rhodamine B can reach 77.35%, exhibiting excellent photocatalytic degradation performance. The catalyst material of this invention is of great significance for reducing the overpotential of the water electrolysis reaction, achieving low-energy hydrogen production, degrading pollutants in water, improving the natural environment, and realizing the resource utilization of wastewater.

[0033] 4. The catalyst material of this invention can also be first applied to the degradation of organic dyes in wastewater, and then the above-degraded wastewater can be used as an electrolyte to further electrocatalyze the process using the prepared catalyst. One catalyst has multiple uses, realizing the resource utilization of wastewater and showing good application prospects. Attached Figure Description

[0034] Figure 1 The X-ray diffraction (XRD) pattern of the basic nickel-cobalt carbonate precursor prepared in Example 1 of this invention.

[0035] Figure 2 The X-ray diffraction (XRD) patterns of the catalyst materials prepared in Examples 1-4 of this invention are shown.

[0036] Figure 3 The image shows a scanning electron microscope (SEM) image of the basic nickel-cobalt carbonate precursor prepared in Example 1 of this invention.

[0037] Figure 4 The image shows a scanning electron microscope (SEM) image of the catalyst material prepared in Example 1 of this invention.

[0038] Figure 5 The image shows the transmission electron microscope (TEM) image of the catalyst material prepared in Example 1 of this invention.

[0039] Figure 6 The image shows a scanning electron microscope (SEM) image of the catalyst material prepared in Example 2 of this invention.

[0040] Figure 7 The image shows a scanning electron microscope (SEM) image of the catalyst material prepared in Example 3 of this invention.

[0041] Figure 8 The image shows a scanning electron microscope (SEM) image of the catalyst material prepared in Example 4 of this invention.

[0042] Figure 9 The image shows the X-ray diffraction (XRD) pattern of the catalyst material prepared in Comparative Example 1 of this invention.

[0043] Figure 10 The image shows the X-ray diffraction (XRD) pattern of the catalyst material prepared in Comparative Example 2 of this invention.

[0044] Figure 11 The graph shows the degradation efficiency of Rhodamine B by photocatalysis under simulated sunlight in Examples 1-4 and Comparative Example 1 of this invention.

[0045] Figure 12 The HER linear sweep voltammetry (LSV) polarization curves are shown for the catalyst materials prepared in Examples 1-4 and Comparative Example 2 of this invention.

[0046] Figure 13 The Tafel slope diagrams of the HER values ​​for the catalyst materials prepared in Examples 1-4 and Comparative Example 2 of this invention are shown.

[0047] Figure 14 The OER linear sweep voltammetry (LSV) polarization curves of the catalyst materials prepared in Examples 1-4 and Comparative Example 2 of this invention are shown.

[0048] Figure 15 The image shows the Tafel slope of the OER of the catalyst materials prepared in Examples 1-4 and Comparative Example 2 of this invention.

[0049] Figure 16 The HER linear sweep voltammetry (LSV) polarization curves of the catalyst prepared in Example 1 of this invention for different electrolytes are shown.

[0050] Figure 17 The OER linear sweep voltammetry (LSV) polarization curves of the catalyst prepared in Example 1 of this invention for different electrolytes. Detailed Implementation

[0051] The present invention will be further described below with reference to specific embodiments. However, it is not limited thereto.

[0052] Furthermore, unless otherwise specified, the experimental methods described in the following embodiments are all conventional methods; and unless otherwise specified, the reagents, materials and apparatus are all commercially available.

[0053] Example 1

[0054] A method for preparing NiSe2 / CoSe / NF nanomaterials using basic nickel-cobalt carbonate as a precursor includes the following steps:

[0055] (1) Cut the nickel foam (1×2cm) 2 The nickel foam was ultrasonicated with acetone, ethanol and ultrapure water for 20 min each, and then dried in a vacuum drying oven at 60℃ for 6 h to obtain the treated nickel foam.

[0056] (2) Take 1 mmol nickel nitrate hexahydrate, 2 mmol cobalt nitrate hexahydrate, 10 mmol urea and 3 mmol ammonium fluoride and add them to 30 mL of ultrapure water. Stir vigorously for 30 min until completely dissolved to obtain a pink clear solution.

[0057] (3) The pink clear solution obtained in step (2) was placed into the reaction vessel, and the nickel foam (NF) treated in step (1) was immersed in the solution and left to stand for 5 minutes. Then, the hydrothermal reaction was carried out at 120°C for 6 hours. The target product obtained by the hydrothermal reaction was thoroughly washed with ultrapure water and anhydrous ethanol, and dried in a vacuum drying oven at 60°C for 12 hours to obtain the precursor material.

[0058] (4) Place the precursor material obtained in step (3) into one end of a ceramic boat and 0.2g of selenium powder into the other end, then cover it. Place the ceramic boat into a tube furnace, with one end of the selenium powder at the inlet and the other end of the precursor material at the outlet. Evacuate the tube furnace three times to remove the air; then introduce nitrogen as a protective gas. N2 is continuously introduced into the tube furnace; the outlet of the tube furnace is connected to the tail gas absorbent liquid, and the bubble rate generated in the tail gas absorbent liquid is 1 bubble / s. Set the tube furnace heating program to 2℃ min. -1 The heating rate was increased to 400℃ and held for 1 hour. After cooling to room temperature, the porcelain boat was removed, yielding a black final product.

[0059] The X-ray diffraction (XRD) pattern of the precursor material prepared in Example 1 is shown below. Figure 1 As shown in the figure, the phase of the prepared precursor material is similar to that of Co(CO3). 0.5 The diffraction peaks of (OH)H2O standard PDF card 48-0083 and Ni2CO3(OH)2H2O standard PDF card 38-0714 are consistent, and no impurity peaks appear, indicating that the precursor material was successfully prepared, and it is recorded as basic nickel-cobalt carbonate precursor.

[0060] The X-ray diffraction (XRD) pattern of the final product (NiSe2 / CoSe / NF-3.0) prepared in Example 1 is as follows: Figure 2 As shown in the figure, the phase of the final product prepared matches the diffraction peaks of NiSe2 (88-1711), CoSe (89-2004), and Ni (70-1849) on the standard PDF card, and no impurity peaks appear, indicating that the material preparation was successful.

[0061] The scanning electron microscope (SEM) image of the basic nickel-cobalt carbonate precursor prepared in Example 1 is shown below. Figure 3 As shown, scanning electron microscope (SEM) and transmission electron microscope (TEM) images of the NiSe2 / CoSe / NF-3.0 catalyst material are as follows: Figure 4-5 As shown. By Figure 3 It can be seen that the basic nickel-cobalt carbonate precursor forms a unique microstructure combining two-dimensional nanosheets and one-dimensional nanowires. The width of the two-dimensional nanosheets is 40-50 μm, and the surface is smooth. The overall morphology of the NiSe2 / CoSe / NF-3.0 obtained after selenization is completely maintained, and the surface is accompanied by the precipitation of 30-50 nm zero-dimensional nanoparticles. Figure 4 ); Figure 5The results clearly show that after selenization, the prepared catalyst exhibits a smooth and flat surface on which 30-50 nm zero-dimensional nanoparticles grow. By controlling the amount of ammonium fluoride added, the optimal molar ratio of nickel nitrate hexahydrate, cobalt nitrate hexahydrate, urea, and ammonium fluoride is 1:2:10:3, resulting in the NiSe2 / CoSe / NF-3.0 catalyst with the best electrocatalytic and photocatalytic properties.

[0062] Example 2

[0063] A method for preparing NiSe2 / CoSe / NF nanomaterials using basic nickel-cobalt carbonate as a precursor includes the following steps:

[0064] (1) Cut the nickel foam (1×2cm) 2 The nickel foam was ultrasonicated with acetone, ethanol and ultrapure water for 20 min each, and then dried in a vacuum drying oven at 60℃ for 6 h to obtain the treated nickel foam.

[0065] (2) Take 1 mmol nickel nitrate hexahydrate, 2 mmol cobalt nitrate hexahydrate, 10 mmol urea and 0 mmol ammonium fluoride and add them to 30 mL of ultrapure water. Stir vigorously for 30 min until completely dissolved to obtain a pink clear solution.

[0066] (3) The pink clear solution obtained in step (2) was placed into the reaction vessel, and the nickel foam (NF) treated in step (1) was immersed in the solution and left to stand for 5 minutes. Then, the hydrothermal reaction was carried out at 120°C for 6 hours. The target product obtained by the hydrothermal reaction was thoroughly washed with ultrapure water and anhydrous ethanol, and then dried in a vacuum drying oven at 60°C for 12 hours to obtain the precursor material.

[0067] (4) Place the precursor material obtained in step (3) into one end of a ceramic boat and 0.2g of selenium powder into the other end, then cover it. Place the ceramic boat into a tube furnace, with one end of the selenium powder at the inlet and the other end of the precursor material at the outlet. Evacuate the tube furnace three times to remove the air; then introduce nitrogen as a protective gas. N2 is continuously introduced into the tube furnace; the outlet of the tube furnace is connected to the tail gas absorbent liquid, and the bubble rate generated in the tail gas absorbent liquid is 1 bubble / s. Set the tube furnace heating program to 2℃ min. -1 The heating rate was increased to 400℃ and held for 1 hour. After cooling to room temperature, the porcelain boat was removed, yielding a black final product.

[0068] The X-ray diffraction (XRD) pattern of the final product (NiSe2 / CoSe / NF-0.0) prepared in Example 2 is shown below. Figure 2As shown in the figure, the phase of the final product prepared matches the diffraction peaks of NiSe2 (88-1711), CoSe (89-2004), and Ni (70-1849) on the standard PDF card, and no impurity peaks appear, indicating that the material was successfully prepared.

[0069] The scanning electron microscope (SEM) image of the NiSe2 / CoSe / NF-0.0 catalyst material prepared in Example 2 is shown below. Figure 6 As shown, the obtained NiSe2 / CoSe / NF-0.0 without the addition of ammonium fluoride formed a sea urchin-like flower sphere with a diameter of 5.5 μm composed of zero-dimensional nanoparticles and one-dimensional nanowires, wherein the nanoparticles have a diameter of 30-50 nm and are grown on one-dimensional nanowires.

[0070] Example 3

[0071] A method for preparing NiSe2 / CoSe / NF nanomaterials using basic nickel-cobalt carbonate as a precursor includes the following steps:

[0072] (1) Cut the nickel foam (1×2cm) 2 The nickel foam was ultrasonicated with acetone, ethanol and ultrapure water for 20 min each, and then dried in a vacuum drying oven at 60℃ for 6 h to obtain the treated nickel foam.

[0073] (2) Take 1 mmol nickel nitrate hexahydrate, 2 mmol cobalt nitrate hexahydrate, 10 mmol urea and 1.5 mmol ammonium fluoride and add them to 30 mL of ultrapure water. Stir vigorously for 30 min until completely dissolved to obtain a pink clear solution.

[0074] (3) The pink clear solution obtained in step (2) was placed into the reaction vessel, and the foamed nickel (NF) treated in step (1) was immersed in the solution and left to stand for 5 minutes. Then, the hydrothermal reaction was carried out at 120°C for 6 hours. The target product obtained by the hydrothermal reaction was thoroughly washed with ultrapure water and anhydrous ethanol, and dried in a vacuum drying oven at 60°C for 12 hours to obtain the precursor material.

[0075] (4) Place the precursor material obtained in step (3) into one end of a ceramic boat and 0.2g of selenium powder into the other end, then cover it. Place the ceramic boat into a tube furnace, with one end of the selenium powder at the inlet and the other end of the precursor material at the outlet. Evacuate the tube furnace three times to remove the air; then introduce nitrogen as a protective gas. N2 is continuously introduced into the tube furnace; the outlet of the tube furnace is connected to the tail gas absorbent liquid, and the bubble rate generated in the tail gas absorbent liquid is 1 bubble / s. Set the tube furnace heating program to 2℃ min. -1 The heating rate was increased to 400℃ and held for 1 hour. After cooling to room temperature, the porcelain boat was removed, yielding a black final product.

[0076] The X-ray diffraction (XRD) pattern of the final product (NiSe2 / CoSe / NF-1.5) prepared in Example 3 is shown below. Figure 2 As shown in the figure, the phase of the final product prepared matches the diffraction peaks of NiSe2 (88-1711), CoSe (89-2004), and Ni (70-1849) on the standard PDF card, and no impurity peaks appear, indicating that the material was successfully prepared.

[0077] The scanning electron microscope (SEM) image of the NiSe2 / CoSe / NF-1.5 catalyst material prepared in Example 3 is shown below. Figure 7 As shown, with the addition of sodium fluoride from 0 mmol to 1.5 mmol, the morphology of the catalyst gradually changed from a one-dimensional nanowire urchin-like structure to a flower-like structure assembled from two-dimensional nanosheets. The two-dimensional nanosheets were woven from nanowires with a diameter of 60-90 nm, and zero-dimensional nanoparticles grew on the surface of the nanowires. This indicates that ammonium fluoride releases F... - It acts as a surface structure modifier.

[0078] Example 4

[0079] A method for preparing NiSe2 / CoSe / NF nanomaterials using basic nickel-cobalt carbonate as a precursor includes the following steps:

[0080] (1) Cut the nickel foam (1×2cm) 2 The nickel foam was ultrasonicated with acetone, ethanol and ultrapure water for 20 min each, and then dried in a vacuum drying oven at 60℃ for 6 h to obtain the treated nickel foam.

[0081] (2) Take 1 mmol nickel nitrate hexahydrate, 2 mmol cobalt nitrate hexahydrate, 10 mmol urea and 4.5 mmol ammonium fluoride and add them to 30 mL of ultrapure water. Stir vigorously for 30 min until completely dissolved to obtain a pink clear solution.

[0082] (3) The pink clear solution obtained in step (2) was placed into the reaction vessel, and the nickel foam (NF) treated in step (1) was immersed in the solution and left to stand for 5 minutes. Then, the hydrothermal reaction was carried out at 120°C for 6 hours. The target product obtained by the hydrothermal reaction was thoroughly washed with ultrapure water and anhydrous ethanol, and then dried in a vacuum drying oven at 60°C for 12 hours to obtain the precursor material.

[0083] (4) Place the precursor material obtained in step (3) into one end of a ceramic boat and 0.2g of selenium powder into the other end, then cover it. Place the ceramic boat into a tube furnace, with one end of the selenium powder at the inlet and the other end of the precursor material at the outlet. Evacuate the tube furnace three times to remove the air; then introduce nitrogen as a protective gas. N2 is continuously introduced into the tube furnace; the outlet of the tube furnace is connected to the tail gas absorbent liquid, and the bubble rate generated in the tail gas absorbent liquid is 1 bubble / s. Set the tube furnace heating program to 2℃ min. -1 The heating rate was increased to 400℃ and held for 1 hour. After cooling to room temperature, the porcelain boat was removed, yielding a black final product.

[0084] The X-ray diffraction (XRD) pattern of the final product (NiSe2 / CoSe / NF-4.5) prepared in Example 4 is shown below. Figure 2 As shown in the figure, the phase of the final product prepared matches the diffraction peaks of NiSe2 (88-1711), CoSe (89-2004), and Ni (70-1849) on the standard PDF card, and no impurity peaks appear, indicating that the material was successfully prepared.

[0085] The scanning electron microscope (SEM) image of the NiSe2 / CoSe / NF-4.5 catalyst material prepared in Example 4 is shown below. Figure 8 As shown, with the addition of sodium fluoride increasing from 3.0 mmol to 4.5 mmol, the morphology of the catalyst gradually dissociated from a flower-like structure composed of self-assembled nanosheets to a flower-like structure composed of nanowires, with zero-dimensional nanoparticles growing on the surface of the nanowires. This indicates that the F released by ammonium fluoride... - It acts as a surface structure modifier.

[0086] Comparative Example 1

[0087] (1) Cut the nickel foam (1×2cm) 2 The nickel foam was ultrasonicated with acetone, ethanol and ultrapure water for 20 min each, and then dried in a vacuum drying oven at 60℃ for 6 h to obtain the treated nickel foam.

[0088] (2) Take 1.5 mmol nickel nitrate hexahydrate, 1.5 mmol cobalt nitrate hexahydrate, 7.5 mmol urea and 3 mmol ammonium fluoride and add them to 30 mL of ultrapure water. Stir vigorously for 30 min until completely dissolved to obtain a clear solution.

[0089] (3) The clarified solution obtained in step (2) is placed into the reaction vessel, and the foamed nickel (NF) treated in step (1) is immersed in the solution and left to stand for 5 minutes. Then, the hydrothermal reaction is carried out at 120°C for 6 hours. The target product obtained by the hydrothermal reaction is thoroughly washed with ultrapure water and anhydrous ethanol, and then placed in a vacuum drying oven at 60°C for 12 hours to obtain the precursor material.

[0090] (4) Place the precursor material obtained in step (3) into one end of a ceramic boat and 0.5g of selenium powder into the other end, then cover it. Place the ceramic boat into a tube furnace, with one end of the selenium powder at the inlet and the other end of the precursor material at the outlet. Evacuate the tube furnace three times to remove the air; then introduce nitrogen as a protective gas. N2 is continuously introduced into the tube furnace; the outlet of the tube furnace is connected to the tail gas absorbent liquid, and the bubble rate generated in the tail gas absorbent liquid is 1 bubble / s. Set the tube furnace heating program to 2℃ min. -1 The heating rate was increased to 350℃ and held for 2 hours. After cooling to room temperature, the porcelain boat was removed, yielding a black final product.

[0091] The X-ray diffraction (XRD) pattern of the final product prepared in Comparative Example 1 is shown below. Figure 9 As shown in the figure, the phases of the final product prepared correspond to those of the standard PDF cards NiSe2 (11-0552) and Co3Se4 (89-2001), and no impurity peaks appear, indicating that the prepared material is a NiSe2 / Co3Se4 material, denoted as NiSe2 / Co3Se4 / NF.

[0092] Comparative Example 2

[0093] (1) Cut the nickel foam (1×2cm) 2 The nickel foam was ultrasonicated with acetone, ethanol and ultrapure water for 20 min each, and then dried in a vacuum drying oven at 60℃ for 6 h to obtain the treated nickel foam.

[0094] (2) Take 1 mmol nickel nitrate hexahydrate, 10 mmol urea and 3 mmol ammonium fluoride and add them to 30 mL of ultrapure water. Stir vigorously for 30 min until completely dissolved to obtain a clear solution.

[0095] (3) The clarified solution obtained in step (2) is placed into the reaction vessel, and the foamed nickel (NF) treated in step (1) is immersed in the solution and left to stand for 5 minutes. Then, the hydrothermal reaction is carried out at 120°C for 6 hours. The target product obtained from the hydrothermal reaction is thoroughly washed with ultrapure water and anhydrous ethanol, and then dried in a vacuum drying oven at 60°C for 12 hours to obtain the precursor material.

[0096] (4) Place the precursor material obtained in step (3) into one end of a ceramic boat and 0.2g of selenium powder into the other end, then cover it. Place the ceramic boat into a tube furnace, with one end of the selenium powder at the inlet and the other end of the precursor material at the outlet. Evacuate the tube furnace three times to remove the air; then introduce nitrogen as a protective gas. N2 is continuously introduced into the tube furnace; the outlet of the tube furnace is connected to the tail gas absorbent liquid, and the bubble rate generated in the tail gas absorbent liquid is 1 bubble / s. Set the tube furnace heating program to 2℃ min. -1 The heating rate was increased to 400℃ and held for 1 hour. After cooling to room temperature, the porcelain boat was removed to obtain the final product.

[0097] The X-ray diffraction (XRD) pattern of the final product prepared in Comparative Example 2 is shown below. Figure 10 As shown, the phase of the final product corresponds to that of the standard PDF card NiSe2 (89-7131), and no impurity peaks appear, indicating that the prepared material is NiSe2 material, which is denoted as NiSe2.

[0098] Experimental Example 1

[0099] The catalysts prepared in Examples 1-4 and Comparative Example 1 were subjected to photocatalytic degradation tests of Rhodamine B. The specific test methods are as follows.

[0100] Three 1×1cm pieces 2 The catalyst sample was dispersed in 25 mL of 10 mg / L Rhodamine B aqueous solution, and then placed in a dark chamber and stirred at room temperature for 20 min to reach adsorption equilibrium. Then, an 800 W xenon lamp simulating sunlight was turned on, and samples were taken every 20 min. The solutions taken each time were centrifuged to separate the supernatant, and the absorbance of the supernatant at the peak (400-650 nm) was measured using a UV-2550 spectrophotometer.

[0101] Figure 11 The graph shows the photocatalytic degradation efficiency of Rhodamine B by the catalysts prepared in Examples 1-4 and Comparative Example 1. The prepared catalyst NiSe2 / CoSe / NF-3.0, i.e., Example 1, achieved a degradation efficiency of 77.35%, which is significantly better than that of Examples 2-4 and Comparative Example 1.

[0102] Experimental Example 2

[0103] The catalysts prepared in Examples 1-4 and Comparative Example 2 were tested for their electrochemical hydrogen evolution and oxygen evolution performance. The specific test methods are as follows.

[0104] LSV testing method for the electrocatalyst HER: A three-electrode system was used, with the prepared catalyst as the working electrode, a graphite rod as the counter electrode, and an Hg / HgO electrode as the reference electrode. A 1M KOH aqueous solution was used as the electrolyte.

[0105] LSV testing method for electrocatalyst OER: A three-electrode system was used, with the prepared catalyst as the working electrode, a graphite rod as the counter electrode, and an Hg / HgO electrode as the reference electrode. A 1M KOH aqueous solution was used as the electrolyte.

[0106] Figure 12 and Figure 13 The LSV and Tafel slope plots of the electrocatalysts HER obtained in Examples 1-4 and Comparative Example 2 are shown. The catalytic materials prepared in Examples 1, 2, 3, 4 and Comparative Example 2 were subjected to a current density of 10 mA / cm². -2 The overpotentials at these times were 131 mV, 292 mV, 174 mV, 183 mV, and 195 mV, respectively. Particularly noteworthy is the overpotential at a current density of 100 mA / cm². -2 In Example 1, the overpotential was only 231 mV and the current density was 200 mA / cm². -2 The overpotential was only 279 mV; the Tafel slopes were 73.77 mV dec. -1 231.69mV dec -1 111.59mV dec -1 124.62mV dec -1 and 131.41mV dec -1 Experimental results show that the bifunctional catalyst prepared in Example 1 has the lowest overpotential and the lowest corresponding Tafel slope, exhibiting the highest electrocatalytic HER activity.

[0107] Figure 14 and Figure 15 The LSV plots and corresponding Tafel slope plots are shown for the OER of the electrocatalysts obtained in Examples 1-4 and Comparative Example 2. The electrocatalyst materials prepared in Examples 1, 2, 3, 4 and Comparative Example 2 were subjected to an OER of 10 mA / cm². -2 The overpotentials at these times were 167mV, 319mV, 245mV, 286mV, and 288mV, respectively. Specifically, at a current density of 50mA / cm², the overpotentials were... -2 In Example 1, the overpotential was only 238mV at a current density of 100mA / cm². -2 In Example 1, the overpotential was only 299 mV; the Tafel slope was 45.51 mV dec. -1 121.94mV dec -1 95.2mV dec -1 113.19mV dec -1 and 119.34mV dec -1Experimental results show that the bifunctional electrocatalyst prepared in Example 1 has the smallest overpotential and the lowest corresponding Tafel slope, exhibiting higher electrocatalytic OER activity.

[0108] Experimental Example 3

[0109] The photocatalytic degradation of Rhodamine B was carried out using the method in Example 1. The degraded solution was centrifuged and prepared into an aqueous KOH solution for electrocatalysis. This solution was used as an electrolyte for the electrocatalytic hydrogen evolution and oxygen evolution analysis. The specific test method is as follows.

[0110] LSV testing method for the electrocatalyst HER: A three-electrode system was used, with the catalyst prepared in Example 1 as the working electrode, a graphite rod as the counter electrode, and an Hg / HgO electrode as the reference electrode. The electrolyte was a 1M KOH aqueous solution prepared by centrifugation after photocatalytic degradation of Rhodamine B.

[0111] LSV test method for electrocatalyst OER: A three-electrode system was used, with the catalyst prepared in Example 1 as the working electrode, a graphite rod as the counter electrode, and an Hg / HgO electrode as the reference electrode. The electrolyte was a 1M KOH aqueous solution prepared by centrifugation after photocatalytic degradation of Rhodamine B.

[0112] Figure 16 The image shows the LSV diagram of the electrocatalyst HER. The electrocatalyst material prepared in Example 1 was used at a current density of 10 mA / cm². -2 The overpotentials for different electrolyte solutions reached 131 mV and 165 mV, respectively. This demonstrates that Example 1 also exhibited excellent HER activity in response to electrolyte displacement.

[0113] Figure 17 The image shows the LSV (Laser Voltage Spectrum) of the electrocatalytic OER. The electrocatalytic material prepared in Example 1 operates at a current density of 10 mA / cm². -2 The overpotentials for different electrolyte solutions reached 167 mV and 297 mV, respectively. This demonstrates that Example 1 also exhibited excellent OER activity for electrolyte displacement.

[0114] In summary, after the photocatalytic degradation of Rhodamine B solution in Example 1, the waste liquid after degradation can be prepared into KOH aqueous solution as an electrocatalytic electrolyte after centrifugation to remove the catalyst. Moreover, the data shows that Example 1 also has excellent hydrogen evolution and oxygen evolution bifunctional performance in this electrolyte, that is, it can be used as a bifunctional electrocatalyst.

Claims

1. An application of a NiSe2 / CoSe / NF nanomaterial with basic nickel-cobalt carbonate as a precursor, characterized in that, It is used as an electrocatalyst in the hydrogen evolution and oxygen evolution reactions of water electrolysis, and as a photocatalyst in the degradation of organic dyes in wastewater; the organic dye is Rhodamine B. The NiSe2 / CoSe / NF nanomaterial is a NiSe2 / CoSe heterostructure nanomaterial supported on a nickel foam surface. The microstructure of the NiSe2 / CoSe / NF nanomaterial is a three-dimensional multi-level nanostructure assembled from zero-dimensional nanoparticles, one-dimensional nanowires, and two-dimensional nanosheets. Among them, the two-dimensional nanosheets are woven from one-dimensional nanowires, and spherical zero-dimensional nanoparticles are loaded on the surface of the nanowires. The two-dimensional nanosheets further self-assemble into a multi-level nanoflower-like structure. The method for preparing NiSe2 / CoSe / NF nanomaterials with basic nickel-cobalt carbonate as the precursor includes the following steps: (1) Cobalt nitrate hexahydrate, nickel nitrate hexahydrate, urea and ammonium fluoride were dissolved in ultrapure water, and pretreated nickel foam was added. The mixture was subjected to hydrothermal reaction. The precursor of basic nickel-cobalt carbonate was obtained by separation, washing and drying. The molar ratio of nickel nitrate hexahydrate, cobalt nitrate hexahydrate, urea and ammonium fluoride was 1:2:10:

3. The hydrothermal reaction temperature was 120℃ and the hydrothermal reaction time was 6h. (2) The basic nickel-cobalt carbonate precursor and selenium powder were placed at both ends of a ceramic boat and covered. The selenium powder was placed near the inlet of the protective gas in the tube furnace, and the basic nickel-cobalt carbonate precursor was placed near the outlet of the protective gas. NiSe2 / CoSe / NF nanomaterials were obtained by calcination under a protective gas atmosphere. The mass ratio of selenium powder to cobalt nitrate hexahydrate in step (1) was 1:2.

91. The calcination conditions were: heating rate 2℃min -1 The calcination temperature was 400℃ and the holding time was 1 h.

2. The application of the NiSe2 / CoSe / NF nanomaterial with basic nickel-cobalt carbonate as the precursor according to claim 1, characterized in that, Step (1) includes one or more of the following conditions: i. The molar ratio of cobalt nitrate hexahydrate to the volume ratio of ultrapure water is (0.1-1):15 mol / L. -1 ; ii. The preparation method of pretreated nickel foam includes the following steps: the nickel foam is ultrasonically treated in acetone, ethanol and ultrapure water for 10-30 min respectively, and then vacuum dried to obtain pretreated nickel foam; the vacuum drying temperature is 50-70℃ and the vacuum drying time is 4-8 h.

3. The application of the NiSe2 / CoSe / NF nanomaterial with basic nickel-cobalt carbonate as the precursor according to claim 1, characterized in that, In step (1), the drying is vacuum drying, the drying temperature is 40-80℃, and the drying time is 6-20 h.

4. The application of the NiSe2 / CoSe / NF nanomaterial with basic nickel-cobalt carbonate as the precursor according to claim 1, characterized in that, Step (2) includes one or more of the following conditions: i. The protective gas is nitrogen or argon; ii. After placing the basic nickel-cobalt carbonate precursor and selenium powder into the tube furnace, the tube furnace is evacuated 2-4 times, and then a protective gas is introduced. iii. During the calcination process, the gas is continuously introduced into the tubular furnace. The gas outlet of the tubular furnace is connected to the tail gas absorption liquid through a pipe. The gas discharged from the pipe generates a bubble rate of (1-3) bubbles / s in the tail gas absorption liquid.

5. The application of the NiSe2 / CoSe / NF nanomaterial with basic nickel-cobalt carbonate as the precursor according to claim 1, characterized in that, The application method includes the following steps: using NiSe2 / CoSe / NF nanomaterials with basic nickel cobalt carbonate as a precursor as a photocatalyst to degrade organic dyes in wastewater, and then separating the wastewater to obtain treated wastewater; then using NiSe2 / CoSe / NF nanomaterials with basic nickel cobalt carbonate as a precursor as an electrocatalyst and the treated wastewater as an electrolyte to carry out electrocatalytic hydrogen evolution reaction (HER) and / or oxygen evolution reaction (OER).

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