A foamed nickel-based Fe-B-S catalyst, a preparation method and application thereof

Abstract

The present application relates to a kind of foamed nickel-based Fe-B-S catalyst and its preparation method and application, and the preparation method is as follows: respectively preparing aqueous solution of iron nitrate as A solution, and aqueous solution of sodium borohydride, sodium hydroxide and sodium thiosulfate as B solution;Foamed nickel after pretreatment is immersed in A solution and B solution in turn alternately, repeat several times, dry after obtaining the foamed nickel-based Fe-B-S catalyst of the present application.The foamed nickel-based Fe-B-S catalyst uses foamed nickel as substrate, which is provided with low crystalline Fe-B-S active layer, the low crystalline Fe-B-S active layer includes Fe-B-S composite grown in situ on the foamed nickel substrate, and the Fe-B-S composite is composed of Fe, B and S element.Compared with prior art, the Fe-B-S catalyst prepared in the present application shows significantly reduced overpotential in oxygen evolution reaction, with the advantages of simple preparation, low cost and high catalytic efficiency.

Description

Technical Field

[0001] This invention relates to the field of electrochemical catalytic materials technology, and in particular to a foamed nickel-based Fe-BS catalyst, its preparation method, and its application. Background Technology

[0002] Hydrogen energy, due to its clean, efficient, and renewable characteristics, is considered an ideal energy carrier for the future. Electrolysis of water is a core technology for achieving large-scale green hydrogen production. However, the slow kinetics of the oxygen evolution reaction (OER) at the anolyte during water electrolysis, requiring a high overpotential, have become a bottleneck restricting the improvement of overall water electrolysis efficiency. Therefore, developing efficient, stable, and low-cost electrocatalysts for the OER is crucial.

[0003] Currently, the best-performing oxygen evolution catalysts are still the noble metals iridium and ruthenium and their oxides, but their high cost and scarcity severely limit their large-scale industrial application. In recent years, non-noble metal-based catalysts, such as oxides, hydroxides, phosphides, and sulfides of transition metals (cobalt, nickel, iron, etc.), have attracted extensive research due to their abundant resources and potential high activity. Among them, transition metal sulfides have proven to be a promising class of oxygen evolution catalysts.

[0004] Therefore, there is an urgent need in this field to develop a new type of electrode material that uses a more abundant and lower-cost metal as its core and can directly construct a highly active and stable catalytic layer on the current collector through a simple process. Summary of the Invention

[0005] The purpose of this invention is to provide a foamed nickel-based Fe-BS catalyst, its preparation method, and its application. The foamed nickel-based Fe-BS catalyst has low raw material cost, is simple to prepare, has excellent catalytic performance, and good stability.

[0006] The objective of this invention can be achieved through the following technical solutions: One objective of this invention is to provide a method for preparing a nickel-based Fe-BS foam catalyst, comprising the following steps: S1. Solution preparation: Prepare solution A and solution B; solution A is an aqueous solution of a soluble iron salt; solution B is an aqueous solution comprising sodium borohydride, sodium hydroxide and sodium thiosulfate; S2. Alternating impregnation: The pretreated nickel foam substrate is alternately impregnated into solution A and solution B in sequence, and repeated several times, so as to grow Fe-BS composite in situ on the surface of the nickel foam substrate. After post-treatment, the nickel foam-based Fe-BS catalyst is obtained.

[0007] Preferably, in step S1, the concentration of the soluble iron salt in solution A is 0.1~1.0 mol / L.

[0008] Preferably, in step S1, the soluble iron salt includes ferric nitrate.

[0009] More preferably, in step S1, the concentration of the soluble iron salt in solution A is 0.5 mol / L.

[0010] Preferably, in step S1, the concentration of sodium borohydride in solution B is 0.5~2.0 mol / L, the concentration of sodium hydroxide is 0.05~0.5 mol / L, and each 10 mL of solution B contains 0.01~0.1 g of sodium thiosulfate.

[0011] More preferably, in step S1, the concentration of sodium borohydride in solution B is 1.0 mol / L and the concentration of sodium hydroxide is 0.1 mol / L.

[0012] More preferably, in step S1, each 10 mL of solution B contains 0.05 g of sodium thiosulfate.

[0013] In this invention, soluble iron salts are used as the Fe source, sodium borohydride as the B source, sodium thiosulfate as the S source, and a nickel foam substrate provides the Ni source and acts as a conductive substrate.

[0014] Preferably, in step S2, the immersion time of the nickel foam substrate in solution A and the immersion time in solution B are both 1 to 30 seconds each time.

[0015] More preferably, in step S2, the immersion time of the nickel foam substrate in solution A and the immersion time in solution B are both 10 seconds each time.

[0016] Preferably, in step S2, the repetition is performed 3 to 10 times.

[0017] More preferably, in step S2, the repetition is performed 5 times.

[0018] Preferably, in step S2, the pretreatment refers to: sequentially ultrasonically cleaning the nickel foam substrate in dilute acid, ethanol, and deionized water, and then drying it for later use.

[0019] Preferably, in step S2, the dilute acid is 0.1~1 mol / L hydrochloric acid or nitric acid.

[0020] Preferably, in step S2, the ultrasonic cleaning specifically refers to ultrasonic cleaning in dilute acid, ethanol, and deionized water for 5-15 minutes each, with an ultrasonic frequency of approximately 30-50 kHz and a power of approximately 100-200 W.

[0021] Preferably, in step S2, the drying refers to vacuum drying at 50~70 ℃ for 5~7 h.

[0022] More preferably, in step S2, the drying refers to vacuum drying at 60 °C for 6 h.

[0023] Preferably, in step S2, the thickness of the nickel foam substrate is 1.0 mm to 2.0 mm.

[0024] Preferably, in step S2, the post-processing refers to removing the nickel foam substrate on which the Fe-BS composite has been grown in situ, rinsing it with deionized water and drying it to obtain the nickel foam-based Fe-BS catalyst.

[0025] More preferably, in the post-processing, drying refers to vacuum drying at 50~70 ℃ for 5~7 h.

[0026] More preferably, the preparation method of the foamed nickel-based Fe-BS catalyst includes the following steps: S1. Pretreatment: The nickel foam substrate is ultrasonically cleaned in dilute hydrochloric acid, ethanol and deionized water in sequence to remove surface oxides and oil stains, and then dried for later use. S2. Solution preparation: Prepare solutions A and B; Solution A is an aqueous solution of a soluble iron salt; Solution B contains sodium borohydride, sodium hydroxide, and sodium thiosulfate; S3. Alternating impregnation: The nickel foam substrate treated in step S1 is alternately impregnated in solution A and solution B in sequence, with each immersion in solution A and solution B constituting one cycle. The cycle is repeated several times to grow active material (Fe-BS composite) on the surface of the nickel foam in situ. S4. Post-processing: The foamed nickel substrate after step S3 is taken out, rinsed with deionized water and dried to obtain the foamed nickel-based Fe-BS catalyst.

[0027] The second objective of this invention is to provide a foamed nickel-based Fe-BS catalyst prepared by the aforementioned preparation method. The catalyst uses foamed nickel as a substrate and has a low-crystallinity Fe-BS active layer disposed thereon. The low-crystallinity Fe-BS active layer includes an Fe-BS composite grown in situ on the foamed nickel substrate, and the Fe-BS composite is composed of Fe, B, and S elements.

[0028] Preferably, the atomic percentage of each element in the foamed nickel-based Fe-BS catalyst is 90-94% Ni; 1%~2% Fe; 5%~6% S; and the balance is B.

[0029] More preferably, the nickel foam substrate has a three-dimensional porous branched framework structure, and the Fe-BS composite is grown in situ on the branched framework structure.

[0030] More preferably, the Fe-BS composite is a low-crystallinity nano-Fe-BS composite.

[0031] More preferably, the nano-Fe-BS composite is discontinuously grown in situ on the branched framework structure, and the catalyst has a rough surface.

[0032] A third objective of this invention is to provide an application of the aforementioned nickel-based Fe-BS foam catalyst, including using the nickel-based Fe-BS foam catalyst as a nickel-based Fe-BS foam oxygen evolution electrode in an alkaline electrolyte for water electrolysis to produce oxygen.

[0033] This invention provides a foamed nickel-based Fe-BS catalyst, which constructs a catalytic active layer on the surface of a foamed nickel substrate using a low-crystallinity Fe-BS composite. This type of structure typically possesses numerous defects and coordination-unsaturated sites, which facilitates the exposure of more electrocatalytic active sites, thereby promoting the oxygen evolution reaction (OER) kinetics. In the foamed nickel-based Fe-BS catalyst of this invention, Fe, B, and S significantly enhance the electrocatalytic performance of the OER through synergistic effects. Specifically, Fe, as the main active metal site, provides electron transfer centers and participates in the formation of hydroxyl intermediates; B doping regulates the local electron density and metal electronic structure, improving electron transport efficiency; and S regulates the electronic environment of the active sites by forming metal sulfides and sulfur oxide species, and optimizes the binding energy of adsorbed intermediates. The synergistic effect of these three elements not only increases the active site density of the catalyst layer but also improves the electron transport pathway and reaction kinetics, thereby significantly reducing the catalyst overpotential, increasing the Tafel slope and reaction rate, and enhancing the stability of the electrode in alkaline media.

[0034] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention provides a foamed nickel-based Fe-BS catalyst and its preparation method and application. The catalyst is prepared by alternating impregnation method. The catalyst uses foamed nickel as a substrate and supports Fe-BS composite as a low crystallinity Fe-BS active layer. The foamed nickel-based Fe-BS catalyst has low raw material cost, simple preparation, excellent catalytic performance and good stability.

[0035] (2) Significantly reduced cost: The Fe-BS complex in this invention is composed of Fe, B and S elements, with iron, which is abundant on Earth, as the main active metal. Soluble iron salt, sodium borohydride and sodium thiosulfate are used as iron source, boron source and sulfur source, respectively. The raw material cost is low, which is conducive to large-scale application.

[0036] (3) This invention constructs a catalytic active layer using a low-crystallinity Fe-BS composite. In the elemental distribution mapping of the Fe-BS / NF electrode, Fe, Ni, and S elements are observed, with Fe and S uniformly distributed on the surface of the catalytic layer. Due to the low atomic number of B, its EDS signal was not detected, but XPS analysis confirmed that Fe, B, and S elements were successfully doped onto the surface of the active layer. This synergistic effect of the elements significantly improves the intrinsic oxygen evolution reaction (OER) catalytic activity of the material and promotes the kinetics of the OER reaction.

[0037] (4) Simple process and strong bonding: The present invention adopts the alternating impregnation method to directly grow catalytic active components on three-dimensional porous nickel foam, avoiding the use of binders, ensuring a strong bonding force and excellent electronic conduction path between the active material and the current collector, thereby improving the structural stability and service life of the electrode. Attached Figure Description

[0038] Figure 1 This is a scanning electron microscope (SEM) image of the nickel foam-based Fe-BS catalyst prepared in Example 1.

[0039] Figure 2 The image shows the energy dispersive spectroscopy (EDS) spot scan elemental analysis of the nickel foam-based Fe-BS catalyst prepared in Example 1.

[0040] Figure 3 The energy dispersive spectroscopy (EDS) surface scan elemental analysis diagrams of the foamed nickel-based Fe-BS catalyst prepared in Example 1 are shown in Figure 1 (a: S elemental distribution diagram; b: Fe elemental distribution diagram).

[0041] Figure 4 The XRD (X-ray diffraction) spectra of the NF in Comparative Example 4 and the foamed nickel-based Fe-BS catalyst prepared in Example 1 are shown.

[0042] Figure 5 The XPS spectrum of the nickel foam-based Fe-BS catalyst prepared in Example 1 is shown below (in the figure, a: full XRD spectrum; b: Fe 2p; c: B 1s; d: C 1s; e: S 2p).

[0043] Figure 6 Linear sweep voltammetry (LSV) curves of the catalyst electrode materials prepared in Example 1 and Comparative Examples 1-4 in 1.0 M KOH solution.

[0044] Figure 7 The images show the Tafel curves of the catalyst electrode materials prepared in Example 1 and Comparative Examples 1-4.

[0045] Figure 8 The stability diagram of the foamed nickel-based Fe-BS catalyst prepared in Example 1 in alkaline medium (1.0 M KOH solution). Detailed Implementation

[0046] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0047] Unless otherwise specified, the reagents, methods, instruments, and equipment used in this invention are conventional in the art. Unless otherwise specified, the reagents and materials used in the following examples are all commercially available.

[0048] This invention provides a method for preparing a foamed nickel-based Fe-BS catalyst, comprising the following steps: S1. Solution Preparation: Prepare solution A and solution B; solution A is an aqueous solution of a soluble iron salt; solution B is an aqueous solution comprising sodium borohydride, sodium hydroxide, and sodium thiosulfate; in solution A, the concentration of the soluble iron salt is 0.1~1.0 mol / L, and the soluble iron salt includes ferric nitrate; in solution B, the concentration of sodium borohydride is 0.5~2.0 mol / L, the concentration of sodium hydroxide is 0.05~0.5 mol / L, and each 10 mL of solution B contains 0.01~0.1 g of sodium thiosulfate.

[0049] S2. Alternating Impregnation: The pretreated nickel foam substrate is alternately impregnated into solution A and solution B, repeated several times, thereby growing the Fe-BS composite in situ on the surface of the nickel foam substrate. After post-treatment, the nickel foam-based Fe-BS catalyst is obtained. The impregnation time of the nickel foam substrate in solution A and solution B is 1-30 seconds each time. The number of repetitions is 3-10 times. The pretreatment refers to ultrasonically cleaning the nickel foam substrate sequentially in dilute acid, ethanol, and deionized water, and then drying it for later use. The dilute acid is 0.1-1 mol / L hydrochloric acid or nitric acid. The ultrasonic cleaning specifically refers to ultrasonic cleaning in dilute acid, ethanol, and deionized water for 5-15 min each. The drying refers to vacuum drying at 50-70 ℃ for 5-7 h.

[0050] Furthermore, the nickel foam-based Fe-BS catalyst prepared according to this method uses nickel foam as a substrate, on which a low-crystallinity Fe-BS active layer is disposed. The low-crystallinity Fe-BS active layer includes an Fe-BS composite grown in situ on the nickel foam substrate. The Fe-BS composite is composed of Fe, B, and S elements. The atomic percentage of each element in the nickel foam-based Fe-BS catalyst is Ni 90-94%; Fe 1%~2%; S 5%~6%; and the balance is B.

[0051] Furthermore, the foamed nickel-based Fe-BS catalyst is used as a foamed nickel-based Fe-BS oxygen evolution electrode in alkaline electrolyte for water electrolysis to produce oxygen.

[0052] In the following examples, the nickel foam used was purchased from Suzhou Keshenghe Metal Materials Co., Ltd., with a thickness of 1.0~2.0 mm, a pore size range of 300~450 μm, a porosity of approximately 90~95%, and an areal density of approximately 250~350 g·m³. -2 .

[0053] Example 1 A method for preparing a foamed nickel-based Fe-BS oxygen evolution electrode includes the following steps: S1. Pretreatment: A piece of nickel foam with a size of 1 cm × 2 cm was ultrasonically cleaned for 10 minutes each in 1 M hydrochloric acid, anhydrous ethanol and deionized water, and then dried in a vacuum drying oven at 60℃ for 6 hours for later use.

[0054] S2. Solution preparation: Prepare solution A and solution B.

[0055] Solution A: 10 mL of 0.5 mol / L ferric nitrate aqueous solution.

[0056] Solution B: Prepare 10 mL of an aqueous solution containing 1.0 mol / L sodium borohydride, 0.1 mol / L sodium hydroxide, and 0.05 g / 10 mL sodium thiosulfate.

[0057] S3. Alternating Immersion: Immerse the treated nickel foam in solution A for 10 seconds, remove it, pause briefly, and then immerse it in solution B for 10 seconds. This completes one cycle. Repeat this cycle 5 times.

[0058] S4. Post-treatment: Rinse the soaked nickel foam with plenty of deionized water and then dry it at 60°C to obtain the final product Fe-BS / NF electrode.

[0059] Comparative Example 1 The only difference from Example 1 is that sodium thiosulfate is not added to solution B; all other steps are exactly the same. The resulting electrode is denoted as Fe-B / NF.

[0060] Comparative Example 2 The only difference from Example 1 is that sodium borohydride and sodium hydroxide are not added to solution B; it contains only 0.05 g / 100 mL sodium thiosulfate. All other steps are identical. The resulting electrode is denoted as Fe-S / NF.

[0061] Comparative Example 3 The nickel foam was immersed five times in solution A (0.5 M ferric nitrate) from Example 1 (10 seconds each time, with no immersion in solution B between each immersion), and then dried. The resulting electrode is denoted as Fe / NF.

[0062] Comparative Example 4 Only nickel foam substrate, denoted as NF.

[0063] Performance testing From the scanning electron microscope image ( Figure 1 It can be observed that the prepared Fe-BS / NF electrode retains the original three-dimensional porous dendritic framework structure of the nickel foam substrate. The Fe-BS composite grows on the surface of the nickel foam in the form of nano-sized particles, exhibiting a discontinuous partial coverage feature, which gives the electrode a rough surface morphology. This structure is beneficial for exposing abundant catalytic active sites and provides sufficient channels for electrolyte transport and gas desorption.

[0064] From the energy spectrum spot scan elemental analysis diagram of Fe-BS / NF ( Figure 2 Fe, S, and Ni elements can be observed in the energy spectrum, indicating the successful fabrication of the Fe-BS / NF electrode. (Due to the low atomic number of B, its energy spectrum signal was not detected). Mapping diagram ( Figure 3 a, Figure 3 b) Further confirmation that Fe and S elements are evenly distributed in the selected region.

[0065] Figure 4 The XRD patterns of NF and Fe-BS / NF are shown. Both NF and Fe-BS / NF exhibit distinct diffraction peaks at 2θ = 44.6°, 52.1°, and 76.5°, which are attributed to the (111), (200), and (220) crystal planes of metallic Ni (JCPDS No. 04-0850), respectively. Compared to bare NF, Fe-BS / NF did not show any additional significant diffraction peaks, indicating that the active layer formed on the nickel foam surface after the introduction of the nano-Fe-BS composite has low crystallinity. Meanwhile, the characteristic peaks of Fe-BS / NF show a slight shift towards lower angles compared to NF, indicating a certain interaction between the introduced active component Fe-BS composite and the NF substrate, thereby causing a change in the local lattice environment. This type of structure typically has more defects and coordination unsaturated sites, which is beneficial for exposing more electrocatalytic active sites, thus promoting the oxygen evolution reaction kinetics.

[0066] Figure 5 XPS spectra of Fe-BS / NF. Figure 5 The XPS full spectrum of a shows the presence of Fe, B, C, and S on the Fe-BS / NF surface, further confirming the successful loading of the Fe-BS composite onto the nickel foam substrate. The Fe 2p XPS spectrum, i.e. Figure 5 b shows that Fe 2+ with Fe 3+ Fe coexists on the catalyst surface. 3+ The dominant species (712.87 eV / 724.09 eV) indicates that FeOOH is the main active species on the catalyst surface. 2+ The presence of auxiliary sites (710.71 eV / 718.46 eV) for electron transfer may contribute to OER activity. The satellite peaks with higher binding energies (725.83 / 731.85 eV) may be related to Fe. 3+ The shake-up process or the electronic environment regulated by local B / S doping is related. Overall, XPS results show that a hydroxyl layer with coexisting divalent and trivalent Fe is formed on the surface of the Fe-BS / NF catalyst, providing abundant active sites for OER. At the same time, it synergistically regulates the electronic structure with S and B doping, thereby enhancing electrocatalytic performance.

[0067] XPS spectrum of B 1s ( Figure 5 c) shows two distinct peaks on the catalyst surface, at 198.62 eV and 191.66 eV. The high binding energy peak (198.62 eV) can be attributed to B atoms interacting with borides formed by the metal element, while the low binding energy peak (191.66 eV) corresponds to boron oxide species of B–O or B–OH. This result indicates that B was successfully introduced into the catalyst surface during solution plasma in-situ deposition. Some B interacted with Fe / Ni / S to form metal borides, while the rest was oxidized to form B–O species. The presence of B may modulate the local electron density, improve electron transport, and synergistically enhance OER activity with the metal active sites, thereby improving the overall electrochemical performance of the catalyst.

[0068] S 2p high-resolution XPS spectrum ( Figure 5 e) Three distinct peaks are observed: 168.35 eV, 163.34 eV, and 161.81 eV. According to literature reports, the low binding energy peak at 161.81 eV can be attributed to S... 2-The presence of ions, specifically sulfur sulfides (M–S) formed by sulfur and metals, indicates that some sulfur has been successfully incorporated into the catalyst lattice or formed chemical bonds with the metal. The intermediate peak at 163.34 eV corresponds to the S–M–O bond formed by S with metal hydroxyl groups or oxides, possibly due to slight oxidation of the catalyst surface in solution or air. The high binding energy peak at 168.35 eV can be attributed to the oxidation state of sulfur (SO₄²⁻). x The presence of sulfur oxides (such as sulfates or sulfur oxides) indicates the presence of small amounts of sulfur oxide species on the surface. Sulfur doping not only stabilizes the electronic structure of the catalyst surface but may also improve adsorption and electron transfer performance during the OER process by regulating the electron density of active metal sites, thereby significantly enhancing the electrochemical activity of the catalyst.

[0069] These results indicate that the Fe-BS / NF catalyst surface contains sulfur elements in various chemical environments, providing abundant active sites for the oxygen evolution reaction and potentially synergistically optimizing electron transport and reaction kinetics with the Fe / B / O components.

[0070] A standard three-electrode system was used, with the prepared electrode as the working electrode, a graphite sheet as the counter electrode, an Hg / HgO electrode as the reference electrode, and a 1.0 M KOH solution as the electrolyte. The electrochemical oxygen evolution performance of the electrode materials prepared in Example 1 and Comparative Examples 1-4 was tested. Before the electrochemical tests, 20 cycles of cyclic voltammetry were performed to activate the material. Then, linear sweep voltammetry (LSV) was performed in the range of 1.1–1.7 V (relative to RHE). 90% iR compensation was applied to the electrode material to reduce potential shift caused by solution resistance.

[0071] The results from the LSV curve show that ( Figure 6 Fe-BS / NF exhibited the highest electrocatalytic activity at 50 mA cm⁻¹. -2 The overpotential at the current density was approximately 220 mV, significantly lower than that of the comparative samples Fe-S / NF (260 mV), Fe / NF (270 mV), Fe-B / NF (284 mV), and the NF substrate (328 mV). This result indicates that the synergistic introduction of Fe, B, and S elements significantly enhances the OER activity of the catalyst, outperforming all comparative materials. Further Tafel slope analysis (Figure 7) shows that the Tafel slope of Fe-BS / NF is only 55.7 mV. -1 It is significantly lower than Fe-S / NF (78 mV dec) -1 ), Fe / NF (63.6 mV dec -1 ), Fe-B / NF (71.7 mV dec) -1 ) and substrate NF (39.3 mV dec -1This indicates that it has the fastest kinetic reaction rate and a more efficient catalytic process.

[0072] To investigate the stability of the Fe-BS / NF catalyst in alkaline medium (1.0 M KOH solution), its stability at 50 mA cm⁻¹ was evaluated using a chronovoltammetric method. -2 Long-term OER electrochemical stability, such as Figure 8 As shown, the Fe-BS / NF catalyst exhibits excellent stability, with only a slight change in potential during a continuous 35-h test. Meanwhile, the LSV polarization curves before and after the stability test (…) Figure 8 The two layers (as shown in the inset) almost overlap, indicating that their OER catalytic activity did not show significant degradation. These results further confirm that the catalyst layer possesses good structural stability and durability.

[0073] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method for preparing a foamed nickel-based Fe-BS catalyst, characterized in that, Includes the following steps: S1. Solution preparation: Prepare solution A and solution B; solution A is an aqueous solution of a soluble iron salt; solution B is an aqueous solution comprising sodium borohydride, sodium hydroxide and sodium thiosulfate; S2. Alternating impregnation: The pretreated nickel foam substrate is alternately impregnated into solution A and solution B in sequence, and repeated several times, so as to grow Fe-BS composite in situ on the surface of the nickel foam substrate. After post-treatment, the nickel foam-based Fe-BS catalyst is obtained.

2. The method for preparing the foamed nickel-based Fe-BS catalyst according to claim 1, characterized in that, In step S1, the concentration of soluble iron salt in solution A is 0.1~1.0 mol / L, and the soluble iron salt includes ferric nitrate.

3. The method for preparing the foamed nickel-based Fe-BS catalyst according to claim 1, characterized in that, In step S1, the concentration of sodium borohydride in solution B is 0.5~2.0 mol / L, the concentration of sodium hydroxide is 0.05~0.5 mol / L, and each 10 mL of solution B contains 0.01~0.1 g of sodium thiosulfate.

4. The method for preparing the foamed nickel-based Fe-BS catalyst according to claim 1, characterized in that, In step S2, the immersion time of the nickel foam substrate in solution A and the immersion time in solution B are both 1 to 30 seconds each time.

5. The method for preparing the foamed nickel-based Fe-BS catalyst according to claim 1, characterized in that, In step S2, the repetition is performed 3 to 10 times.

6. The method for preparing the foamed nickel-based Fe-BS catalyst according to claim 1, characterized in that, In step S2, the pretreatment refers to: ultrasonically cleaning the nickel foam substrate in dilute acid, ethanol and deionized water in sequence, and then drying it for later use.

7. The method for preparing the foamed nickel-based Fe-BS catalyst according to claim 6, characterized in that, In step S2, the dilute acid is 0.1~1 mol / L hydrochloric acid or nitric acid, the ultrasonic cleaning specifically refers to ultrasonic cleaning in dilute acid, ethanol and deionized water for 5~15 min each, with an ultrasonic frequency of about 30~50 kHz and a power of about 100~200 W, and the drying refers to vacuum drying at 50~70 ℃ for 5~7 h.

8. A foamed nickel-based Fe-BS catalyst prepared by the preparation method according to any one of claims 1 to 7, characterized in that, The catalyst uses nickel foam as a substrate, on which a low-crystallinity Fe-BS active layer is disposed. The low-crystallinity Fe-BS active layer includes an Fe-BS composite grown in situ on the nickel foam substrate, and the Fe-BS composite is composed of Fe, B and S elements.

9. The foamed nickel-based Fe-BS catalyst according to claim 8, characterized in that, The atomic percentage of each element in the foamed nickel-based Fe-BS catalyst is Ni 90-94%; Fe 1%~2%; S 5%~6%; with the balance being B.

10. The application of a foamed nickel-based Fe-BS catalyst prepared by the preparation method according to any one of claims 1 to 7, characterized in that, This includes using the foamed nickel-based Fe-BS catalyst as a foamed nickel-based Fe-BS oxygen evolution electrode in an alkaline electrolyte for water electrolysis to produce oxygen.

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