A nanomaterial with gold clusters dispersed on the surface of iron-cobalt-nickel sulfide, a preparation method and application thereof and an electrolytic seawater oxygen evolution method

Abstract

The application belongs to the technical field of water electrolysis oxygen evolution, and particularly relates to a kind of nanomaterial with gold cluster dispersed on the surface of iron-cobalt-nickel sulfide, its preparation method and application and electrolysis seawater oxygen evolution method.The nanomaterial comprises: iron-cobalt-nickel sulfide substrate and gold cluster dispersed on the surface of the iron-cobalt-nickel sulfide substrate;The size of the gold cluster is 1.0nm to 2.0nm.The application constructs a kind of composite nanomaterial with micro "sea-island" synergistic anti-chlorine structure.Iron-cobalt-nickel sulfide substrate is a continuous "sea" phase carrier, and high dispersion anchored specific size gold cluster is "island" phase material."Sea-island" synergistically builds a continuous and high-strength "negative electrostatic repulsion field" to resist chlorine ion corrosion.

Description

Technical Field

[0001] This invention belongs to the field of oxygen evolution technology in water electrolysis, specifically relating to a nanomaterial in which gold clusters are dispersed on the surface of iron-cobalt-nickel sulfide, its preparation method, and its application in the method of oxygen evolution through seawater electrolysis. Background Technology

[0002] Water electrolysis technology is widely considered a sustainable solution for green hydrogen production. Seawater, accounting for nearly 96.5% of the world's water resources, is an ideal feedstock for hydrogen electrolysis, helping to alleviate freshwater shortages. However, seawater contains a high concentration of chloride ions (approximately 0.41 mol / L). In anodic electrolysis, chloride ions may be adsorbed and oxidized, leading to electrode surface corrosion. Furthermore, the anodic oxygen evolution reaction (OER) relies on a four-electron-proton coupling transfer process, exhibiting a high thermodynamic energy barrier and slow kinetics, resulting in a high overpotential. Under operating current density, when the overpotential exceeds the standard redox potential difference between the OER and the chlorination oxidation reaction (ClOR), a chlorine evolution side reaction is easily initiated, generating Cl2 or ClO. – These compounds, along with other byproducts, not only pollute the environment but also reduce the Faradaic efficiency and long-term stability of catalysts. In recent years, various electrodes, such as nitrides, phosphides, sulfides, and selenides, have been identified that undergo in-situ surface transformation during electrochemical polarization, spontaneously generating anion-rich compounds (such as PO42-) within the electric double layer region. 3- SO4 2- MoO4 2- VO4 3- A dynamic shielding network (such as those for chloride ions and anodes) is used to repel chloride ions and protect the anode from corrosion. Furthermore, researchers have found that some noble metals (Ir, Ag, etc.) can form strong coordination interactions with partially free chloride ions at the interface, hindering the adsorption of chloride ions in the solution during alkaline seawater electrolysis through the like-ion repulsion effect. However, in real-world applications, fresh seawater needs to be continuously added to replenish the water molecules consumed during electrolysis. However, salts in seawater, especially NaCl, do not directly participate in the reaction, leading to localized NaCl enrichment. Under high current densities, this exacerbates the corrosion of electrode materials by chloride ions, hindering the further development of seawater electrolysis.

[0003] Specifically, currently common catalysts exhibit poor stability and short stabilization time in simulated seawater electrolysis. In recent years, researchers have industrially demonstrated that the in-situ conversion anion layer and noble metal loading strategies mentioned above are powerful means of resisting chlorine corrosion, but certain limitations still exist.

[0004] In the process of developing this application, the inventors discovered that, in the prior art, for noble metal catalytic materials, on the one hand, traditional noble metal nanoparticles, due to their large size and high surface energy, are prone to aggregation or detachment from the support surface during long-term OER catalysis, leading to irreversible decay of catalytic activity. Furthermore, excessively high noble metal loading also greatly limits their large-scale application. On the other hand, while emerging noble metal single-atom materials maximize atom utilization, they are limited by the spatial isolation of their sites. In the electrochemical reaction interface, a single isolated noble metal site, due to steric hindrance and coordination limitations, can only adsorb and bind a single chloride ion. This point-like, discrete charge distribution cannot form a continuous and high-intensity negative electrostatic repulsion field at the microscale, and cannot effectively resist the continuous attack of high-concentration chloride ions, resulting in inherent limitations in its resistance to chloride corrosion.

[0005] For anion layers, different anions differ in coverage and repulsive force; for example, PO4 has a smaller radius. 3- While anions exhibit strong repulsion against chloride ions, their coverage is insufficient, and larger-radius anions have the opposite effect. Therefore, a single anion layer cannot simultaneously satisfy both high coverage and strong repulsion. Furthermore, the high anode positive bias under high current density conditions generates an extremely strong Coulombic attraction between the anode and free chloride ions in the electrolyte. This attraction is sufficient to overcome the electrostatic repulsion of conventional in-situ derived polyanion barrier layers on sulfur / phosphide surfaces. Moreover, the in-situ converted anion shielding layer is continuously eroded and peeled off during long-term seawater electrolysis operation due to the continuous flow and renewal of the electrolyte, ultimately leading to the failure of the traditional anion shielding protection system. Therefore, reducing the precious metal loading or developing a new strategy to achieve stronger or more comprehensive resistance to chloride ion corrosion is a key challenge that must be addressed in the development of novel, high-efficiency seawater electrolysis anode catalysts.

[0006] To address the above problems, this invention is proposed. Summary of the Invention

[0007] The first aspect of this application provides a nanomaterial in which gold clusters are dispersed on the surface of an iron-cobalt-nickel sulfide, the nanomaterial comprising: an iron-cobalt-nickel sulfide substrate and gold clusters dispersed on the surface of the iron-cobalt-nickel sulfide substrate; the size of the gold clusters is 1.0 nm to 2.0 nm.

[0008] Preferably, the gold clusters are uniformly distributed on the surface of the iron-cobalt-nickel sulfide substrate.

[0009] Preferably, the gold cluster is a gold cluster composed of 15 gold single atoms.

[0010] Therefore, the gold clusters in this application are strictly distinguished from single gold atoms and gold nanoparticles in terms of size and the number of gold atoms. The size of gold nanoparticles is generally greater than 2 nm, and more preferably greater than or equal to 5 nm.

[0011] Preferably, the nanomaterial further includes a conductive carrier, and the iron-cobalt-nickel sulfide substrate is loaded on the conductive carrier.

[0012] Preferably, the conductive carrier is selected from: foamed metal, carbon paper, or carbon cloth. The foamed metal can be selected from foamed iron, foamed nickel, etc.

[0013] The second aspect of this application provides a method for preparing the nanomaterial described in the first aspect, in which gold clusters are dispersed on the surface of an iron-cobalt-nickel sulfide, the preparation method comprising:

[0014] Iron-cobalt-nickel hydroxide is provided, and then the iron-cobalt-nickel hydroxide is sulfided to obtain iron-cobalt-nickel sulfide;

[0015] A water-soluble gold cluster dilute solution with a concentration of 10-5000 mmol / L was prepared as the electrolyte. An iron-cobalt-nickel sulfide and a carbon rod were used to form a two-electrode system, with the iron-cobalt-nickel sulfide as the working electrode and the carbon rod as the counter electrode. A positive current of 0.5-10 mA / cm² was applied for chronopotential electrodeposition for 20-3600 seconds. After the electrodeposition was completed, the working electrode was washed and dried to obtain the gold cluster nanomaterial dispersed on the surface of the iron-cobalt-nickel sulfide.

[0016] Preferably, the method for preparing the water-soluble gold clusters is as follows:

[0017] First, solid gold chloride, glutathione, and water were prepared into a solution and stirred evenly. Then, sodium hydroxide solution and anhydrous ethanol were added in sequence and stirred evenly again. Sodium borohydride was added for reduction. After reacting for 5 hours, the mixture was centrifuged, the precipitate was washed, and dried to obtain a stable gold cluster material.

[0018] This gold cluster material can be uniformly dispersed in water, hence it is called a water-soluble gold cluster. The structure of this gold cluster material is: a gold atom as the core and a glutathione ligand wrapped around it.

[0019] The water-soluble gold cluster dilute solution is a mixed solution of gold cluster material, potassium bicarbonate and water.

[0020] Preferably, the method for obtaining iron-cobalt-nickel sulfide by sulfidation of iron-cobalt-nickel hydroxide is as follows:

[0021] Iron-cobalt-nickel hydroxide and sulfur-containing substances are calcined simultaneously in a tube furnace to obtain the corresponding non-precious metal sulfides.

[0022] Preferably, the calcination operation is as follows: heating to 350 degrees Celsius at a rate of 3 degrees Celsius / minute, and heating at this temperature for 1 hour.

[0023] Preferably, the sulfur-containing substance can be selected from a suitable form, such as thiourea, elemental sulfur, etc.

[0024] The preparation method of iron-cobalt-nickel hydroxide can be either wet chemical hydrothermal method or electrochemical deposition method.

[0025] The wet chemical hydrothermal method includes the following steps:

[0026] A mixed solution containing urea and water-soluble iron, nickel, and cobalt salts is subjected to a hydrothermal reaction with a conductive material at a temperature of 100-150°C for 1-20 hours. The mixture is then washed and dried to obtain a conductive carrier material loaded with iron-cobalt-nickel hydroxide. The urea concentration in the mixed solution is 5-25 mmol / 30 mL. The water-soluble iron, nickel, and cobalt salts are their respective nitrates, sulfates, or chlorides, each with a concentration of 1-5 mmol / 30 mL.

[0027] The electrodeposition method includes the following steps:

[0028] A mixed solution of water-soluble iron salt, water-soluble nickel salt, and water-soluble cobalt salt was prepared as the electrolyte. A two-electrode system was formed by a conductive carrier and a carbon rod, with the conductive carrier serving as the working electrode and the carbon rod as the counter electrode. A chronocurrent electrodeposition was performed under an applied negative potential of -0.5 to -2 volts for 50-1000 seconds. After the electrodeposition was completed, the working electrode was washed and dried to obtain a conductive carrier material loaded with iron-cobalt-nickel hydroxide. The concentrations of the water-soluble iron salt, water-soluble nickel salt, and water-soluble cobalt salt in the mixed solution were 1-5 mmol / 30 mL.

[0029] A third aspect of this application provides the application of the nanomaterial described in any one of the first aspects in the electrolysis of seawater as an oxygen evolution material. The electrolyte for the seawater electrolysis contains an alkali.

[0030] A fourth aspect of this application provides a method for oxygen evolution through seawater electrolysis, the method comprising:

[0031] The nanomaterial described in any one of the first aspects is used as the working electrode, a platinum sheet as the counter electrode, a saturated calomel electrode as the reference electrode, and an alkaline sodium chloride solution as the electrolyte, wherein the concentration of the alkali is 1 mol / L and the concentration of sodium chloride is 0-1.5 mol / L; the applied current density is 1 ampere / cm².

[0032] The alkali used in this article can be selected from one or more of sodium hydroxide, potassium hydroxide, etc.

[0033] The above technical solutions can be freely combined, provided they do not contradict each other.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] 1. This invention designs a nanomaterial in which gold clusters are dispersed on the surface of iron, cobalt and nickel sulfides.

[0036] First, a non-precious metal substrate—an iron-cobalt-nickel sulfide substrate—is selected that can undergo structural transformation under OER conditions. In the initial stage of seawater OER electrolysis, a dynamic sulfur-oxygen anion protective layer is formed on the electrode surface by sacrificing the substrate surface. This negatively charged layer repels chloride ions in seawater through electrostatic repulsion, serving as the first layer of protection against chloride ion corrosion and improving the stability of seawater electro-oxidation.

[0037] However, the high positive bias voltage of the anode under high current density conditions causes the anode to generate an extremely strong Coulombic attraction to free chloride ions in the electrolyte. This attraction is sufficient to overcome the electrostatic repulsion of the in-situ derived sulfoxy anion barrier layer on the conventional sulfide surface, ultimately causing the traditional anion shielding protection system to fail. At this time, gold clusters have a strong adsorption effect on chloride ions, fixing chloride ions to form stable gold chloride. In particular, gold clusters break through the limitation of traditional single-atom anodes, which cannot form a field due to site isolation, and thus cannot resist chloride ion penetration. Gold clusters have continuous metal-metal bonds and a wider reaction interface, which can simultaneously adsorb multiple non-bonded free chloride ions. These highly aggregated non-bonded chloride ions around the clusters generate extremely strong local electrostatic repulsion, and have a synergistic coupling effect with the polyanions derived from the iron-cobalt-nickel sulfide support, jointly constructing a continuous and high-intensity "negative electrostatic repulsion field" on the catalyst / anode surface. This repulsive field constructs a robust physical and electrochemical dual barrier, greatly hindering the penetration of chloride ions into the material interior, serving as a second layer of protection against chloride ion corrosion. The metal spacing within the cluster is greater than the chlorine-chlorine bonding distance, blocking Cl-Cl coupling through spatial geometric steric hindrance, preventing the generation of chlorine gas, and thus further corroding the electrode. The synergistic effect of these two strategies enables the electrode to operate stably for more than 2000 hours at ampere-level current densities.

[0038] Therefore, this invention constructs a composite nanomaterial with a microscopic "sea-island" synergistic anti-chloride structure. An iron-cobalt-nickel sulfide substrate serves as a continuous "sea" phase carrier, while highly dispersed, specifically sized gold clusters act as "island" phases. This "sea-island" synergy creates a continuous and high-intensity "negative electrostatic repulsion field" to resist chloride ion corrosion.

[0039] 2. In addition, the ultra-small metal clusters not only reduce the amount of precious metal gold used, thus reducing the cost of the catalyst, but also facilitate large-scale commercialization.

[0040] 3. Finally, the gold cluster / iron-cobalt-nickel sulfide also exhibits extremely excellent low-energy-consumption oxygen evolution performance in water electrolysis. Compared to gold atoms with completely discrete energy levels and gold particles with continuous energy bands (exhibiting a metallic state), the 1.0-2.0 nm gold cluster is in a transitional state between the two, possessing unique molecular-like discrete energy levels and a special HOMO-LUMO band gap. Therefore, this gold cluster can utilize the characteristics of discontinuous energy levels and quantum size effects to precisely control interfacial electronic coupling, thereby reducing the oxygen evolution overpotential and significantly improving catalytic activity.

[0041] 4. This application unexpectedly discovered that, compared to gold particle / iron-cobalt-nickel sulfide materials and gold atom / iron-cobalt-nickel sulfide materials, the gold cluster / iron-cobalt-nickel sulfide material of this application exhibits superior activity and stability when used for seawater electrochemical oxygen desorption (OER). Furthermore, it can operate stably for extended periods in alkaline, high-concentration brine, maintaining good stability and corrosion resistance. The reason for this is that gold atoms, with their point-like, discrete charge distribution, cannot form a continuous and high-intensity negative electrostatic repulsion field at the microscale, thus failing to effectively resist the continuous attack of high-concentration chloride ions. Simultaneously, due to the spatial isolation of their sites, gold single atoms completely lack the cohesive support of metal-metal bonds (such as Au-Au bonds). In environments with strong anodic polarization and high chloride ion concentrations, isolated noble metal single atoms are highly susceptible to oxidation-coordination complexation, resulting in loss of activity. Gold particles, with their large size and high surface energy, are prone to Oswald ripening during long-term OER catalysis to reduce surface free energy, leading to aggregation or detachment from the support surface, resulting in irreversible decay of catalytic activity. The gold clusters with a size of 1.0 nm to 2.0 nm prepared by the specific method in this application can avoid the defects of the gold atoms and gold particles mentioned above. In the high-potential oxidation environment of high-concentration salt water, these clusters composed of 15 gold atoms are not easy to lose activity or to agglomerate rapidly. Instead, they can be stably loaded on the iron-cobalt-nickel sulfide support and work stably for a long time. Attached Figure Description

[0042] Figure 1 This is a transmission electron microscope (TEM) image of the iron-cobalt-nickel sulfide substrate obtained in Example 1.

[0043] Figure 2 This is a transmission electron microscope (TEM) image of the gold 15 clusters obtained in Example 1.

[0044] Figure 3 The image shows the UV-Vis absorption spectrum of the gold 15 cluster obtained in Example 1.

[0045] Figure 4 The Fourier transform infrared spectrum of the gold 15 cluster obtained in Example 1 is shown.

[0046] Figure 5 This is a transmission electron microscope (TEM) image of the gold 15 cluster / iron-cobalt-nickel sulfide obtained in Example 1.

[0047] Figure 6 The image shows the aberration-corrected electron microscope image and elemental distribution map of the gold 15 cluster / iron-cobalt-nickel sulfide obtained in Example 1.

[0048] Figure 7 The image shows the X-ray diffraction pattern of the gold 15 cluster / iron cobalt nickel sulfide obtained in Example 1.

[0049] Figure 8 The polarization curves of the gold 15 cluster / iron cobalt nickel sulfide obtained in Example 1 in 1 mol / L sodium hydroxide and 1 mol / L sodium hydroxide + 0.5 mol / L sodium chloride solutions are shown.

[0050] Figure 9 The stability curves of the gold 15 cluster / iron cobalt nickel sulfide obtained in Example 1 under a constant current of 100 mA / cm² in solutions of 1 mol / L sodium hydroxide + 0.5 mol / L sodium chloride, 1 mol / L sodium hydroxide + 1 mol / L sodium chloride, and 1 mol / L sodium hydroxide + 1.5 mol / L sodium chloride.

[0051] Figure 10 The stability curve of the gold 15 cluster / iron cobalt nickel sulfide obtained in Example 1 in simulated seawater (1 mol / L sodium hydroxide + 0.5 mol / L sodium chloride) under a constant current of 1 A / cm².

[0052] Figure 11 The UV-Vis absorption spectrum of the gold 25 cluster obtained in Comparative Example 1 is shown.

[0053] Figure 12 The image shows a transmission electron microscope (TEM) image of the gold 25 cluster / iron-cobalt-nickel sulfide obtained in Comparative Example 1.

[0054] Figure 13 The polarization curves of the gold 25 cluster / iron cobalt nickel sulfide obtained in Comparative Example 1 are shown in 1 mol / L sodium hydroxide and 1 mol / L sodium hydroxide + 0.5 mol / L sodium chloride solutions.

[0055] Figure 14 The image shows the UV-Vis absorption spectrum of the gold 11 cluster obtained in Comparative Example 2.

[0056] Figure 15 This is a transmission electron microscope (TEM) image of the gold 11 cluster / iron-cobalt-nickel sulfide obtained in Comparative Example 2.

[0057] Figure 16 The polarization curves of the gold 11 cluster / iron cobalt nickel sulfide obtained in Comparative Example 2 are shown in 1 mol / L sodium hydroxide and 1 mol / L sodium hydroxide + 0.5 mol / L sodium chloride solutions.

[0058] Figure 17The image shows the UV-Vis absorption spectrum of the gold 22 cluster obtained in Comparative Example 3.

[0059] Figure 18 This is a transmission electron microscope (TEM) image of the gold 22 cluster / iron-cobalt-nickel sulfide obtained in Comparative Example 3.

[0060] Figure 19 The polarization curves of the gold 22 cluster / iron cobalt nickel sulfide obtained in Comparative Example 3 are shown in 1 mol / L sodium hydroxide and 1 mol / L sodium hydroxide + 0.5 mol / L sodium chloride solutions.

[0061] Figure 20 This is a transmission electron microscope (TEM) image of the gold atom / iron-cobalt-nickel sulfide obtained in Comparative Example 4.

[0062] Figure 21 The polarization curves of the gold atom / iron-cobalt-nickel sulfide obtained in Comparative Example 4 are shown in 1 mol / L sodium hydroxide and 1 mol / L sodium hydroxide + 0.5 mol / L sodium chloride solutions.

[0063] Figure 22 The stability curve of the gold atom / iron cobalt nickel sulfide obtained in Comparative Example 4 in simulated seawater (1 mol / L sodium hydroxide + 0.5 mol / L sodium chloride) under a constant current of 1 A / cm² is shown.

[0064] Figure 23 This is a transmission electron microscope (TEM) image of the gold particles / iron-cobalt-nickel sulfide obtained in Comparative Example 5.

[0065] Figure 24 The polarization curves of the gold particles / iron-cobalt-nickel sulfide obtained in Comparative Example 5 are shown in 1 mol / L sodium hydroxide and 1 mol / L sodium hydroxide + 0.5 mol / L sodium chloride solutions.

[0066] Figure 25 The stability curve of the gold particles / iron-cobalt-nickel sulfide obtained in Comparative Example 5 in simulated seawater (1 mol / L sodium hydroxide + 0.5 mol / L sodium chloride) under a constant current of 1 A / cm² is shown. Detailed Implementation

[0067] The present invention will be described below with reference to specific embodiments, but the implementation of the present invention is not limited thereto. Experimental methods not specifically described in the embodiments generally use conventional conditions and conditions described in the manual, or conditions recommended by the manufacturer. The general equipment, materials, reagents, etc., used are all commercially available unless otherwise specified. The raw materials used in the following embodiments and comparative examples are all commercially available.

[0068] In electrochemical testing, iR compensation is achieved by subtracting the ohmic voltage drop (iR) of the solution in real time to eliminate the potential deviation caused by the internal resistance of the electrolyte, thereby restoring the true reaction potential at the electrode surface. In the application examples and comparative application examples of this application, the polarization curves ( Figure 8 , 13 (16, 19, 21, 24) are all curves after iR compensation, which eliminates the resistance changes caused by different conductivity in different electrolytes.

[0069] Example 1

[0070] The preparation method of gold-15 clusters dispersed on the surface of iron-cobalt-nickel sulfide nanomaterials (gold clusters / iron-cobalt-nickel sulfide) involves preparing the substrate using the wet chemical hydrothermal method described in the second aspect of this invention, and loading the gold clusters using an electrochemical deposition method, as detailed below:

[0071] Step (1) Preparation of iron-cobalt-nickel sulfides:

[0072] A 30 mL solution was prepared by dissolving 0.731 g of nickel nitrate, 0.202 g of ferric nitrate, 0.405 g of cobalt nitrate, 0.6 g of urea, 0.3 g of ammonium fluoride, and deionized water. The solution was poured into a 40 mL high-pressure reactor. A clean 2 x 4 cm² piece of foamed nickel-iron was then immersed in the solution. The high-pressure reactor was then placed in an oven for hydrothermal crystallization at 140°C for 15 hours. The resulting material was washed three times with water and ethanol, and dried at 80°C for 6 hours to obtain foamed nickel-iron loaded with iron, cobalt, and nickel hydroxide.

[0073] Step (2) The foamed nickel-iron loaded with iron-cobalt-nickel hydroxide obtained in step (1) and 1 gram of thiourea are placed together in a tube furnace and heated to 350 degrees Celsius at a rate of 3 degrees Celsius / minute for 1 hour to carry out a sulfidation reaction to obtain an iron-cobalt-nickel sulfide substrate, which is used for electrodeposition of gold clusters.

[0074] See the transmission electron microscope image of the obtained iron-cobalt-nickel sulfide substrate. Figure 1 ,from Figure 1 It is evident that the iron-cobalt-nickel sulfide on the iron-cobalt-nickel sulfide substrate is a nanoflower structure composed of wrinkled nanosheets.

[0075] Step (3) Synthesis of gold clusters: 0.05 g of gold chloride, 0.08 g of glutathione and deionized water were mixed to make a 50 mL solution. After stirring for 5 minutes, 10 mL of sodium hydroxide solution with a concentration of 1 mol / L was added. After stirring for 5 minutes, 70 mL of anhydrous ethanol was added. After stirring for 5 minutes, 30 mg of sodium borohydride was added. After reacting for 3 hours, the mixture was centrifuged. The precipitate was washed three times with water and ethanol respectively. It was dried at 40 degrees Celsius for 6 hours to obtain stable gold cluster material.

[0076] Step (4) Prepare 50 mL of electrodeposition solution: 5 mg of gold 15 cluster material obtained in step (3), 0.5 g of potassium bicarbonate and deionized water are mixed to form 50 mL of solution.

[0077] Step (5) Electrochemical deposition: A two-electrode system was used in the electrolyte obtained in step (4). The iron-cobalt-nickel sulfide substrate obtained in step (2) was used as the working electrode, and the carbon rod was used as the counter electrode. The chronopotential method was used with the following parameters: deposition current 3 mA / cm², test time 1000 s. The obtained material was washed three times with water and ethanol, and dried at 40 degrees Celsius for 6 hours to obtain gold 15 cluster / iron-cobalt-nickel sulfide material.

[0078] Characterization of gold-15 cluster / iron-cobalt-nickel sulfide materials:

[0079] See the transmission electron microscope image of the obtained gold clusters. Figure 2 ,from Figure 2 It is evident that the diameter of the gold clusters is less than 2 nanometers. For the UV-Vis absorption spectra of the gold cluster / iron-cobalt-nickel sulfide materials, see [link to relevant documentation]. Figure 3 Two broad characteristic absorption peaks were observed near 375 nm and 410 nm for the gold 15 cluster, while no absorption peak was observed for the glutathione ligand at these locations, indicating the formation of an ultrasmall gold 15 cluster with molecular optical absorption characteristics. A gold 15 cluster is defined as a cluster containing 15 gold atoms.

[0080] For the Fourier transform infrared spectra of gold cluster / iron-cobalt-nickel sulfide materials, see [link to Fourier transform infrared spectra]. Figure 4 The spectrum of the prepared gold 15 cluster sample did not show ν(SH) = 2523 cm⁻¹. -1 The absorption band confirmed that glutathione is linked to gold clusters in the form of thiols.

[0081] In the electrochemical deposition method, the key steps are to control the concentration of gold 15 clusters in the electrolyte, the value of the electrodeposition current, and the chronopotential electrodeposition time to ensure that the gold 15 clusters are bonded to the surface atoms of the substrate, forming a strong metal-carrier interaction, thereby achieving strong anchoring of the gold 15 clusters.

[0082] See the transmission electron microscope image of the obtained gold 15 cluster / iron cobalt nickel sulfide. Figure 5 ,from Figure 5 It can be seen that the gold clusters are smaller than 2 nanometers, specifically 1-2 nm, and are uniformly distributed on the surface of iron-cobalt-nickel sulfide.

[0083] The aberration-corrected electron micrographs and elemental distributions of the obtained gold 15 clusters / iron-cobalt-nickel sulfides are shown in [reference]. Figure 6 .from Figure 6 It can be seen that gold, nickel, iron, cobalt and sulfur elements are evenly distributed on the surface of iron-cobalt-nickel sulfide.

[0084] The X-ray diffraction pattern of the obtained gold 15 cluster / iron cobalt nickel sulfide is shown in [reference]. Figure 7 ,from Figure 7 The diffraction peaks of the material are consistent with those of iron cobalt nickel sulfide. No diffraction peaks corresponding to the gold bulk are observed, indicating that the synthesized gold-15 clusters are very small.

[0085] Application Example 1

[0086] First, performance test of seawater electrolysis

[0087] The oxygen evolution performance of the gold 15 cluster / iron-cobalt-nickel sulfide in seawater electrolysis according to Example 1 of this invention was tested using a three-electrode system: the gold 15 cluster / iron-cobalt-nickel sulfide in Example 1 was used as the working electrode, a platinum sheet as the counter electrode, and a saturated calomel electrode as the reference electrode. The test was conducted in a mixed solution of sodium hydroxide and sodium chloride. In the mixed solution, the concentration of sodium hydroxide was 1 mol / L and the concentration of sodium chloride was 0.5 mol / L, denoted as 1 mol / L sodium hydroxide + 0.5 mol / L sodium chloride. The above results were compared with the test results in the 1 mol / L sodium hydroxide solution, and the resulting polarization curve is shown below. Figure 8 As shown. From Figure 8 It is evident that for the gold-15 cluster / iron-cobalt-nickel sulfide material, the oxygen evolution performance is better after adding chloride ions to the electrolyte than when tested in pure sodium hydroxide. The overpotential is reduced by 45 mV at a current density of 500 mA / cm² (the overpotential is 344 mV in sodium hydroxide; and 299 mV in both sodium hydroxide and sodium chloride).

[0088] The gold 15 cluster / iron-cobalt-nickel sulfide of Example 1 underwent constant current stability testing at 100 mA / cm² under different salt concentrations to evaluate its corrosion resistance and stability. The obtained constant current data are shown in [reference needed]. Figure 9 . Figure 9 In the experiment, the sodium chloride concentration was initially doubled compared to simulated real seawater (0.5 mol / L), and gradually increased to three times. The gold-15 cluster / iron-cobalt-nickel sulfide material was tested continuously for 100 hours in electrolytes with different salt concentrations, and the entire test was conducted with uninterrupted electrolysis for 300 hours. Industrially, as electrolysis progresses, the seawater is continuously concentrated, and the chloride ion concentration continuously increases. However, the gold-15 cluster / iron-cobalt-nickel sulfide electrode can still operate stably under this scenario.

[0089] In addition, the gold 15 cluster / iron-cobalt-nickel sulfide was subjected to a constant current stability test of 1 A / cm² under simulated seawater conditions (1 mol / L sodium hydroxide + 0.5 mol / L sodium chloride) to evaluate its corrosion resistance and stability. The obtained constant current data are available in [reference needed]. Figure 10 . Figure 10 It is evident that the gold-15 cluster / iron-cobalt-nickel sulfide material can be stably electrolyzed in simulated seawater for more than 2000 hours.

[0090] Comparative Example 1

[0091] The preparation method of gold-25 clusters dispersed on the surface of iron-cobalt-nickel sulfide nanomaterials (gold-25 clusters / iron-cobalt-nickel sulfide) uses the wet chemical hydrothermal method described in the second aspect of the present invention to prepare the substrate, and uses an electrochemical deposition method to load the gold clusters, as detailed below:

[0092] Step (1) Preparation of iron-cobalt-nickel sulfides:

[0093] A 30 mL solution was prepared by dissolving 0.731 g of nickel nitrate, 0.202 g of ferric nitrate, 0.405 g of cobalt nitrate, 0.6 g of urea, 0.3 g of ammonium fluoride, and deionized water. The solution was poured into a 40 mL high-pressure reactor. A clean 2 x 4 cm² piece of foamed nickel-iron was then immersed in the solution. The reactor was then placed in an oven at 140°C for 15 hours for hydrothermal crystallization. The resulting material was washed three times with water and ethanol, and dried at 80°C for 6 hours to obtain foamed nickel-iron loaded with iron, cobalt, and nickel hydroxide.

[0094] Step (2) The foamed nickel-iron loaded with iron-cobalt-nickel hydroxide obtained in step (1) and 1 gram of thiourea are placed together in a tube furnace and heated to 350 degrees Celsius at a rate of 3 degrees Celsius / minute for 1 hour to carry out a sulfidation reaction to obtain an iron-cobalt-nickel sulfide substrate, which is used for electrodeposition of gold clusters.

[0095] Step (3) Synthesis of Gold 25 Clusters: 0.49 g of chloroauric acid, 0.767 g of glutathione, and deionized water were mixed to form a 50 mL solution. The mixture was stirred for 2 minutes, and the solution color changed from yellow to milky white. 1.5 mL of 1 mol / L sodium hydroxide solution was added, and the solution quickly became clear and transparent. The mixture was stirred for 2 minutes. Then, 62.5 mL of ethanol was added, and the mixture was stirred for 2 minutes. Subsequently, 0.5 mL of an ice-cold sodium borohydride alkaline solution was added (43 mg of sodium borohydride was dissolved in 10 mL of ice-cold 0.2 mol / L NaOH solution), and the glass stopper was quickly tightened. After reacting for three hours, the brown solution was centrifuged, washed three times with ethanol, and dried in a vacuum drying oven to obtain the Gold 25 clusters.

[0096] Step (4) Prepare 50 mL of electrodeposition solution: 5 mg of gold 25 cluster material obtained in step (3), 0.5 g of potassium bicarbonate and deionized water are mixed to form 50 mL of solution.

[0097] Step (5) Electrochemical deposition: A two-electrode system was used in the electrolyte obtained in step (4). The iron-cobalt-nickel sulfide substrate obtained in step (2) was used as the working electrode, and the carbon rod was used as the counter electrode. The chronopotential method was used with the following parameters: deposition current 3 mA / cm², test time 1000 s. The obtained material was washed three times with water and ethanol, and dried at 40 degrees Celsius for 6 hours to obtain gold 25 cluster / iron-cobalt-nickel sulfide material.

[0098] In the electrochemical deposition method, the key steps are: controlling the concentration of gold-25 clusters in the electrolyte, the electrodeposition current value, and the chronopotential electrodeposition time to ensure that the gold-25 clusters are bonded to the surface atoms of the substrate, forming a strong metal-carrier interaction, thereby achieving strong anchoring of the gold-25 clusters.

[0099] See the UV-Vis absorption spectrum of the gold 25 cluster / iron-cobalt-nickel sulfide material. Figure 11 Two broad characteristic absorption peaks were observed around 400, 450, and 670 nm for the gold 25 cluster, while no absorption peak was observed for the glutathione ligand at these locations, indicating the formation of ultrasmall gold 25 clusters with molecular optical absorption characteristics. A gold 25 cluster is defined as a cluster containing 25 gold atoms.

[0100] See the transmission electron microscope image of the obtained gold 25 cluster / iron cobalt nickel sulfide. Figure 12 ,from Figure 12 It can be seen that the size of the gold-25 clusters is less than 2 nanometers, specifically 1-2 nm, and they are uniformly distributed on the surface of the iron-cobalt-nickel sulfide.

[0101] Comparative Application Example 1

[0102] First, performance test of seawater electrolysis

[0103] The oxygen evolution performance of the gold 25 cluster / iron-cobalt-nickel sulfide in Comparative Example 1 of this invention was tested using a three-electrode system: the gold 25 cluster / iron-cobalt-nickel sulfide in Comparative Example 1 was used as the working electrode, a platinum sheet as the counter electrode, and a saturated calomel electrode as the reference electrode. The test was conducted in a mixed solution of sodium hydroxide and sodium chloride. In the mixed solution, the concentration of sodium hydroxide was 1 mol / L and the concentration of sodium chloride was 0.5 mol / L, denoted as 1 mol / L sodium hydroxide + 0.5 mol / L sodium chloride. The results were compared with the test results in the 1 mol / L sodium hydroxide solution, and the resulting polarization curve is shown below. Figure 13 As shown. From Figure 13As can be seen, for the gold 25 cluster / iron-cobalt-nickel sulfide material, the oxygen evolution performance is better after adding chloride ions to the electrolyte than when tested in pure sodium hydroxide, with the overpotential decreasing by 41 mV at a current density of 500 mA / cm² (the overpotential in sodium hydroxide is 346 mV; the overpotential in both sodium hydroxide and sodium chloride is 305 mV). However, the overpotential of the gold 25 cluster / iron-cobalt-nickel sulfide in Comparative Example 1 is still higher than that of the gold 15 cluster / iron-cobalt-nickel sulfide in Example 1. This indicates that the gold 15 cluster has an unexpected technical effect in this system.

[0104] Comparative Example 2

[0105] A method for preparing nanomaterials (gold 11 clusters / iron cobalt nickel sulfide) with gold 11 clusters dispersed on the surface of iron cobalt nickel sulfide, wherein the substrate is prepared by the wet chemical hydrothermal method described in the second aspect of the present invention, and the gold clusters are loaded by electrochemical deposition, as detailed below:

[0106] Step (1) Preparation of iron-cobalt-nickel sulfides:

[0107] A 30 mL solution was prepared by dissolving 0.731 g of nickel nitrate, 0.202 g of ferric nitrate, 0.405 g of cobalt nitrate, 0.6 g of urea, 0.3 g of ammonium fluoride, and deionized water. The solution was poured into a 40 mL high-pressure reactor. A clean 2 x 4 cm² piece of foamed nickel-iron was immersed in the solution. The high-pressure reactor was placed in an oven and subjected to hydrothermal crystallization at 140°C for 15 hours. The resulting material was washed three times with water and ethanol, and dried at 80°C for 6 hours to obtain foamed nickel-iron loaded with iron, cobalt, and nickel hydroxide.

[0108] Step (2) The foamed nickel-iron loaded with iron-cobalt-nickel hydroxide obtained in step (1) and 1 gram of thiourea are placed together in a tube furnace and heated to 350 degrees Celsius at a rate of 3 degrees Celsius / minute for 1 hour to carry out a sulfidation reaction to obtain an iron-cobalt-nickel sulfide substrate, which is used for electrodeposition of gold clusters.

[0109] Step (3) Synthesis of gold 11 cluster: 0.79 g of chloroauric acid and 0.61 g of glutathione were dissolved in 20 mL of ethanol and stirred for several hours. The resulting white precipitate was collected and washed three times with ethanol and dried under vacuum. Then, 70 mg of the dried precipitate was dispersed in 15 mL of ethanol and stirred for 15 minutes. 5 mg of sodium borohydride dissolved in alcohol solvent was quickly added. After the solution turned brown, it was heated at 70 degrees Celsius overnight. Finally, it was washed four times with n-hexane and extracted twice with ethanol to obtain gold 11 cluster.

[0110] Step (4) Prepare 50 mL of electrodeposition solution: 5 mg of gold 11 cluster material obtained in step (3), 0.5 g of potassium bicarbonate and deionized water are mixed to form 50 mL of solution.

[0111] Step (5) Electrochemical deposition: A two-electrode system was used in the electrolyte obtained in step (4). The iron-cobalt-nickel sulfide substrate obtained in step (2) was used as the working electrode, and the carbon rod was used as the counter electrode. The chronopotential method was used with the following parameters: deposition current 3 mA / cm², test time 1000 s. The obtained material was washed three times with water and ethanol, and dried at 40 degrees Celsius for 6 hours to obtain gold 11 cluster / iron-cobalt-nickel sulfide material.

[0112] In the electrochemical deposition method, the key steps are: controlling the concentration of gold 11 clusters in the electrolyte, the electrodeposition current value, and the chronopotential electrodeposition time to ensure that the gold 11 clusters are bonded to the surface atoms of the substrate, forming a strong metal-carrier interaction, thereby achieving strong anchoring of the gold 11 clusters.

[0113] See the UV-Vis absorption spectra of the gold 11 cluster / iron-cobalt-nickel sulfide material. Figure 14 Two broad characteristic absorption peaks were observed near 410 and 510 nm for the gold 11 cluster, while no absorption peak was observed for the glutathione ligand at these locations, indicating the formation of ultrasmall gold 11 clusters with molecular optical absorption characteristics. A gold 11 cluster is defined as a cluster containing 11 gold atoms.

[0114] See the transmission electron microscope image of the obtained gold 11 cluster / iron cobalt nickel sulfide. Figure 15 ,from Figure 15 It can be seen that the size of the gold 11 clusters is less than 2 nanometers, specifically 1-2 nm, and they are uniformly distributed on the surface of the iron-cobalt-nickel sulfide.

[0115] Comparative Application Example 2

[0116] First, performance test of seawater electrolysis

[0117] The oxygen evolution performance of the gold 11 cluster / iron-cobalt-nickel sulfide in Comparative Example 2 of this invention was tested using a three-electrode system: the gold 11 cluster / iron-cobalt-nickel sulfide in Comparative Example 2 was used as the working electrode, a platinum sheet as the counter electrode, and a saturated calomel electrode as the reference electrode. The test was conducted in a mixed solution of sodium hydroxide and sodium chloride. In the mixed solution, the concentration of sodium hydroxide was 1 mol / L and the concentration of sodium chloride was 0.5 mol / L, denoted as 1 mol / L sodium hydroxide + 0.5 mol / L sodium chloride. The above results were compared with the test results in the 1 mol / L sodium hydroxide solution, and the resulting polarization curve is shown below. Figure 16 As shown. From Figure 16As can be seen, for the gold 11 cluster / iron-cobalt-nickel sulfide material, the oxygen evolution performance is better after adding chloride ions to the electrolyte than when tested in pure sodium hydroxide, with the overpotential decreasing by 42 mV at a current density of 500 mA / cm² (the overpotential in sodium hydroxide is 363 mV; the overpotential in both sodium hydroxide and sodium chloride is 321 mV). However, the overpotential of the gold 11 cluster / iron-cobalt-nickel sulfide in Comparative Example 2 is still higher than that of the gold 15 cluster / iron-cobalt-nickel sulfide in Example 1. This indicates that the gold 15 cluster has an unexpected technical effect in this system.

[0118] Comparative Example 3

[0119] The preparation method of gold-22 clusters dispersed on the surface of iron-cobalt-nickel sulfide nanomaterials (gold-22 clusters / iron-cobalt-nickel sulfide) involves preparing the substrate using the wet chemical hydrothermal method described in the second aspect of this invention, and loading the gold clusters using an electrochemical deposition method, as detailed below:

[0120] Step (1) Preparation of iron-cobalt-nickel sulfides:

[0121] A 30 mL solution was prepared by dissolving 0.731 g of nickel nitrate, 0.202 g of ferric nitrate, 0.405 g of cobalt nitrate, 0.6 g of urea, 0.3 g of ammonium fluoride, and deionized water. The solution was poured into a 40 mL high-pressure reactor. A clean 2 x 4 cm² piece of foamed nickel-iron was immersed in the solution. The high-pressure reactor was placed in an oven for hydrothermal crystallization at 140°C for 15 hours. The resulting material was washed three times with water and ethanol, and dried at 80°C for 6 hours to obtain foamed nickel-iron loaded with iron, cobalt, and nickel hydroxide.

[0122] Step (2) The foamed nickel-iron loaded with iron-cobalt-nickel hydroxide obtained in step (1) and 1 gram of thiourea are placed together in a tube furnace and heated to 350 degrees Celsius at a rate of 3 degrees Celsius / minute for 1 hour to carry out a sulfidation reaction to obtain an iron-cobalt-nickel sulfide substrate, which is used for electrodeposition of gold clusters.

[0123] Step (3) Synthesis of gold-22 clusters: 0.197 g of chloroauric acid, 0.154 g of glutathione and deionized water were mixed to form a 50 mL solution. After stirring vigorously for 2 minutes, the pH value was adjusted to 11 with 1 mol / L sodium hydroxide solution. Then, carbon monoxide bubbles were passed through the solution for 1 minute. After stirring vigorously at 500 rpm for 30 minutes, the pH value was adjusted to 2.5 with 1 mol / L hydrochloric acid and stirred continuously for 3 days. The brown solution was centrifuged, washed three times with ethanol, and dried in a vacuum drying oven to obtain gold-22 clusters.

[0124] Step (4) Prepare 50 mL of electrodeposition solution: 5 mg of gold 22 cluster material obtained in step (3), 0.5 g of potassium bicarbonate and deionized water are mixed to form 50 mL of solution.

[0125] Step (5) Electrochemical deposition: A two-electrode system was used in the electrolyte obtained in step (4). The iron-cobalt-nickel sulfide substrate obtained in step (2) was used as the working electrode, and the carbon rod was used as the counter electrode. The chronopotential method was used with the following parameters: deposition current 3 mA / cm², test time 1000 s. The obtained material was washed three times with water and ethanol, and dried at 40 degrees Celsius for 6 hours to obtain gold-22 cluster / iron-cobalt-nickel sulfide material.

[0126] In the electrochemical deposition method, the key steps are: controlling the concentration of gold-22 clusters in the electrolyte, the electrodeposition current value, and the chronopotential electrodeposition time to ensure that the gold-22 clusters are bonded to the surface atoms of the substrate, forming a strong metal-carrier interaction, thereby achieving strong anchoring of the gold-22 clusters.

[0127] See the UV-Vis absorption spectrum of the gold-22 cluster / iron-cobalt-nickel sulfide material. Figure 17 Two broad characteristic absorption peaks were observed in the gold-22 nanoclusters near 455 nm and 520 nm, while no absorption peak was observed for glutathione ligands at these locations, indicating the formation of ultrasmall gold-22 nanoclusters with molecular optical absorption characteristics. The gold-22 cluster refers to a cluster containing 22 gold atoms.

[0128] See the transmission electron microscope image of the obtained gold 22 cluster / iron cobalt nickel sulfide. Figure 18 ,from Figure 18 It can be seen that the size of the gold-22 clusters is less than 2 nanometers, specifically 1-2 nm, and they are uniformly distributed on the surface of the iron-cobalt-nickel sulfide.

[0129] Comparative Application Example 3

[0130] First, performance test of seawater electrolysis

[0131] The oxygen evolution performance of the gold-22 cluster / iron-cobalt-nickel sulfide of Comparative Example 3 in seawater electrolysis was tested using a three-electrode system: the gold-22 cluster / iron-cobalt-nickel sulfide of Comparative Example 3 was used as the working electrode, a platinum sheet as the counter electrode, and a saturated calomel electrode as the reference electrode. The test was conducted in a mixed solution of sodium hydroxide and sodium chloride. In the mixed solution, the concentration of sodium hydroxide was 1 mol / L and the concentration of sodium chloride was 0.5 mol / L, denoted as 1 mol / L sodium hydroxide + 0.5 mol / L sodium chloride. The above results were compared with the test results in the 1 mol / L sodium hydroxide solution, and the resulting polarization curve is shown below. Figure 19 As shown. From Figure 19As can be seen, for the gold-22 cluster / iron-cobalt-nickel sulfide material, the oxygen evolution performance is better after adding chloride ions to the electrolyte than when tested in pure sodium hydroxide, with the overpotential decreasing by 31 mV at a current density of 500 mA / cm² (the overpotential in sodium hydroxide is 351 mV; the overpotential in both sodium hydroxide and sodium chloride is 320 mV). However, the overpotential of the gold-22 cluster / iron-cobalt-nickel sulfide in Comparative Example 3 is still higher than that of the gold-15 cluster / iron-cobalt-nickel sulfide in Example 1. This indicates that the gold-15 cluster has an unexpected technical effect in this system.

[0132] Comparative Example 4

[0133] The preparation method of gold atoms dispersed on the surface of iron-cobalt-nickel sulfide nanomaterials, using electrochemical deposition, is as follows:

[0134] Step (1) Preparation of iron-cobalt-nickel sulfides:

[0135] A 100 mL solution was prepared by dissolving 3.3 g of nickel nitrate, 7.1 g of ferric nitrate, 3.3 g of cobalt nitrate, and deionized water. A three-electrode system was used, with a 3 x 3 cm² nickel-cobalt foam as the working electrode, a carbon rod as the counter electrode, and a saturated calomel electrode as the reference electrode. A chronoamperometry method was employed with the following parameters: deposition potential -1.6 V and test time 800 s. The resulting material was washed three times with water and ethanol, and dried at 80°C for 6 hours to obtain nickel-cobalt foam loaded with ferric-cobalt-nickel hydroxide.

[0136] Step (2) Place the foamed nickel cobalt loaded with iron cobalt nickel hydroxide obtained in step (1) and 1 gram of thiourea together in a tube furnace, heat it to 350 degrees Celsius at a rate of 3 degrees Celsius / minute, and heat it at a constant temperature for 1 hour to carry out the sulfidation reaction to obtain the iron cobalt nickel sulfide substrate.

[0137] Step (3) Prepare 50 ml of electrodeposition solution: Mix 2.0 g of sodium hydroxide and 1.8 mg of chloroauric acid with an appropriate amount of water to prepare 50 ml of solution.

[0138] Step (4) Electrochemical deposition: A three-electrode system was used in the electrolyte obtained in step (3). The iron-cobalt-nickel sulfide substrate obtained in step (2) was used as the working electrode, the carbon rod as the counter electrode, and the saturated calomel electrode as the reference electrode. Cyclic voltammetry was used with the following parameters: voltage range -1 to 0V, scanning direction reversed, scanning speed 0.005V / s, and 10 revolutions. The obtained material was washed three times with water and ethanol, and dried at 60 degrees Celsius for 6 hours to obtain gold atom / iron-cobalt-nickel sulfide material.

[0139] See the transmission electron microscope image of the obtained gold atom / iron cobalt nickel sulfide. Figure 20 ,from Figure 20It is evident that gold atoms are uniformly distributed on the surface of the iron-cobalt-nickel sulfide. This indicates that in Comparative Example 4, the gold element is distributed as individual gold atoms on the surface of the iron-cobalt-nickel sulfide, and does not aggregate into gold clusters or gold particles.

[0140] Comparative Application Example 4

[0141] The oxygen evolution performance of the gold atom / iron-cobalt-nickel sulfide of Comparative Example 4 was tested using a three-electrode system: the gold atom / iron-cobalt-nickel sulfide of Comparative Example 4 was used as the working electrode, a platinum sheet as the counter electrode, and a saturated calomel electrode as the reference electrode. The tests were conducted in 1 mol / L sodium hydroxide and 0.5 mol / L sodium chloride solutions, and the obtained polarization curves are shown below. Figure 21 As shown. From Figure 21 It is evident that for the gold atom / iron-cobalt-nickel sulfide material, the oxygen evolution performance was better after adding chloride ions to the electrolyte than when tested in pure sodium hydroxide, with the overpotential decreasing by 30 mV at a current density of 500 mA / cm² (the overpotential in sodium hydroxide was 382 mV; the overpotential in both sodium hydroxide and sodium chloride was 352 mV). However, when used for seawater electrolysis, the activity of the gold atom / iron-cobalt-nickel sulfide in Comparative Example 4 was lower than that of the gold cluster / iron-cobalt-nickel sulfide in Example 1 and Comparative Examples 1, 2, and 3.

[0142] In addition, the gold atom / iron-cobalt-nickel sulfide was subjected to a constant current stability test of 1 amp / cm² under simulated seawater conditions (1 mol / L sodium hydroxide + 0.5 mol / L sodium chloride) to evaluate its corrosion resistance and stability. The obtained constant current data are available in [reference needed]. Figure 22 The gold atom / iron-cobalt-nickel sulfide material can only be stably electrolyzed in simulated seawater for 180 hours.

[0143] Comparative Example 5

[0144] A method for preparing nanomaterials (gold particles / iron-cobalt-nickel sulfides) with noble metal particles dispersed on the surface of a non-noble metal substrate.

[0145] Following the method of Comparative Example 4, a non-precious metal substrate, namely iron-cobalt-nickel sulfide, was prepared. The only difference from Comparative Example 4 was that in step (4), the cyclic voltammetry parameters were adjusted to: voltage range -3 to 0V, scanning direction reversed, scanning speed 0.005V / s, and the number of cycles increased to 25 cycles. The resulting material was gold particles / iron-cobalt-nickel sulfide.

[0146] See the transmission electron microscope image of the obtained gold particles / iron-cobalt-nickel sulfide. Figure 23 ,from Figure 23 It is evident that the gold particles are larger than 2 nanometers in size, with a basic size of 5 nm, and are uniformly distributed on the surface of the iron-cobalt-nickel sulfide. This indicates that in Comparative Example 2, the gold element is distributed on the surface of the iron-cobalt-nickel sulfide in the form of gold particles larger than 2 nanometers in size, and is neither dispersed into individual gold atoms nor forms gold clusters smaller than 2 nanometers in size.

[0147] Comparative Application Example 5

[0148] The oxygen evolution performance of the gold particles / iron-cobalt-nickel sulfide of Comparative Example 2 was tested using a three-electrode system: the gold particles / iron-cobalt-nickel sulfide of Comparative Example 5 was used as the working electrode, a platinum sheet as the counter electrode, and a saturated calomel electrode as the reference electrode. The tests were conducted in 1 mol / L sodium hydroxide and 0.5 mol / L sodium chloride solutions, and the obtained polarization curves are shown below. Figure 24 As shown. From Figure 24 It is evident that for the gold particle / iron-cobalt-nickel sulfide material, the oxygen evolution performance was better after adding chloride ions to the electrolyte than when tested in pure sodium hydroxide, with the overpotential decreasing by 24 mV at a current density of 500 mA / cm² (compared to 389 mV in sodium hydroxide and 365 mV in both sodium hydroxide and sodium chloride). However, when used for seawater electrolysis, the activity of the gold particle / iron-cobalt-nickel sulfide in Comparative Example 5 was lower than that of the gold cluster / iron-cobalt-nickel sulfide in Example 1 and Comparative Examples 1, 2, and 3, and the gold atom / iron-cobalt-nickel sulfide in Comparative Example 4.

[0149] In addition, the gold particles / iron-cobalt-nickel sulfide were subjected to a constant current stability test of 1 amp / cm² under simulated seawater conditions (1 mol / L sodium hydroxide + 0.5 mol / L sodium chloride) to evaluate its corrosion resistance and stability. The obtained constant current data are available in [reference needed]. Figure 25 The gold particle / iron-cobalt-nickel sulfide material can be stably electrolyzed in simulated seawater for 1000 hours.

[0150] The comparative examples 1, 2, 3, 4, and 5 above demonstrate that, compared to gold particle / iron-cobalt-nickel sulfide materials and gold atom / iron-cobalt-nickel sulfide materials, the gold 15 cluster / iron-cobalt-nickel sulfide material of this application exhibits superior activity and stability when used for seawater electrolytic oxygen desorption. Furthermore, it can operate stably for extended periods in alkaline, high-concentration brine, maintaining good stability and corrosion resistance.

Claims

1. A nanomaterial in which gold clusters are dispersed on the surface of an iron-cobalt-nickel sulfide, characterized in that, The nanomaterial comprises: an iron-cobalt-nickel sulfide substrate and gold clusters dispersed on the surface of the iron-cobalt-nickel sulfide substrate; The size of the gold clusters is from 1.0 nm to 2.0 nm.

2. The nanomaterial with gold clusters dispersed on the surface of iron-cobalt-nickel sulfide according to claim 1, characterized in that, The gold cluster is a gold cluster composed of 15 gold single atoms.

3. The nanomaterial with gold clusters dispersed on the surface of iron-cobalt-nickel sulfide according to claim 1, characterized in that, The nanomaterial also includes a conductive carrier, on which the iron-cobalt-nickel sulfide substrate is loaded.

4. The nanomaterial with gold clusters dispersed on the surface of iron-cobalt-nickel sulfide according to claim 3, characterized in that, The conductive carrier is selected from: foamed metal, carbon paper or carbon cloth.

5. A method for preparing nanomaterials of gold clusters dispersed on the surface of iron-cobalt-nickel sulfides as described in claim 1, characterized in that, The preparation method includes: Iron-cobalt-nickel hydroxide is provided, and then the iron-cobalt-nickel hydroxide is sulfided to obtain iron-cobalt-nickel sulfide; A water-soluble gold cluster dilute solution with a concentration of 10-5000 mmol / L was prepared as the electrolyte. An iron-cobalt-nickel sulfide and a carbon rod were used to form a two-electrode system, with the iron-cobalt-nickel sulfide as the working electrode and the carbon rod as the counter electrode. A positive current of 0.5-10 mA / cm² was applied for chronopotential electrodeposition for 20-3600 seconds. After the electrodeposition was completed, the working electrode was washed and dried to obtain the gold cluster nanomaterial dispersed on the surface of the iron-cobalt-nickel sulfide.

6. The method for preparing nanomaterials with gold clusters dispersed on the surface of iron-cobalt-nickel sulfides according to claim 5, characterized in that, The method for obtaining iron-cobalt-nickel sulfide by sulfidation of iron-cobalt-nickel hydroxide is as follows: Iron-cobalt-nickel hydroxide and sulfur-containing substances are calcined simultaneously in a tube furnace to obtain iron-cobalt-nickel sulfide.

7. The method for preparing nanomaterials with gold clusters dispersed on the surface of iron-cobalt-nickel sulfides according to claim 6, characterized in that, The calcination operation is as follows: the temperature is increased to 350 degrees Celsius at a rate of 3 degrees Celsius / minute, and heated at this temperature for 1 hour.

8. The method for preparing nanomaterials with gold clusters dispersed on the surface of iron-cobalt-nickel sulfides according to claim 5, characterized in that, The water-soluble gold clusters are glutathione-protected gold cluster materials.

9. The application of the nanomaterial according to any one of claims 1-4 in the electrolysis of seawater oxygen evolution materials.

10. A method for oxygen evolution through seawater electrolysis, characterized in that, The method includes the following steps: Using the nanomaterial described in any one of claims 1-4 as the working electrode, a platinum sheet as the counter electrode, a saturated calomel electrode as the reference electrode, and an alkaline sodium chloride solution as the electrolyte, wherein the concentration of the alkali is 1 mol / L and the concentration of sodium chloride is 0-1.5 mol / L; The applied current density is 1 ampere per square centimeter.

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