A cobalt-nickel-iron ternary metal phosphide electrocatalytic electrode based on a foamed iron-nickel support, its preparation method and application

Abstract

This invention provides a cobalt-nickel-iron ternary metal phosphide electrocatalytic electrode based on a foamed iron-nickel support, its preparation method, and its application. The electrode comprises a foamed iron-nickel support and an in-situ grown cobalt-nickel-iron ternary metal phosphide three-dimensional nanosheet array active layer. Using foamed iron-nickel as both the support and the iron and nickel metal source, a cobalt salt precursor is grown in situ in a specific solvent via a one-step hydrothermal-phosphating reaction, resulting in an electrode immobilized with the cobalt-nickel-iron ternary metal phosphide. This integrated electrode solves the problem of easy detachment in traditional deposition methods. Under alkaline conditions, this electrode exhibits excellent hydrogen evolution activity. When two identical electrodes are used as the cathode and anode for the total water splitting reaction, only 1.52 V is required to achieve 10 mA cm⁻¹. ‑2 Furthermore, it maintains stability for over 100 hours. This invention employs a simple and mild process that requires no binders, providing a technical pathway for developing stable non-precious metal water electrolysis catalysts.

Description

Technical Field

[0001] This invention belongs to the field of electrocatalytic materials and new energy technology, specifically relating to an integrated bifunctional electrode for alkaline water electrolysis, particularly a cobalt-nickel-iron ternary metal phosphide electrocatalytic electrode grown in situ on a foamed iron-nickel support, its preparation method, and its application in hydrogen evolution reaction and total hydrolysis. Background Technology

[0002] Hydrogen energy, as a clean and efficient secondary energy source, shows broad application prospects. Among them, alkaline water electrolysis technology is considered an important pathway to achieve green hydrogen production due to its potential for coupling with renewable energy. However, the large-scale application of this technology is still limited by its high energy consumption. Specifically, the oxygen evolution reaction (OER) involves a complex four-electron transfer process with particularly slow kinetics; similarly, the hydrogen evolution reaction (HER) in alkaline media is constrained by the slow kinetics of the water molecule dissociation step. Therefore, developing non-precious metal electrocatalysts that can simultaneously and efficiently catalyze both the HER and OER reactions is crucial for reducing the operating voltage of electrolyzers and improving energy conversion efficiency.

[0003] Among non-noble metal catalysts, transition metal phosphides (TMPs) have shown great potential in both HER and OER processes due to their metalloid conductivity and tunable electronic structure. Nickel-iron phosphide (NiFeP), in particular, has proven to be a promising OER catalyst through the synergistic effect between Ni and Fe (Journal of Alloys and Compounds, 2025, 1018, 179208). However, this system suffers from a significant performance imbalance: its excellent catalytic ability for OER does not extend to the HER process. This is mainly due to insufficient optimization of the adsorption free energy (ΔG_H) of the hydrogen intermediate (H) by the inherent electronic structure of the NiFeP interface, resulting in slow HER kinetics, which has become a bottleneck restricting its application as a bifunctional catalyst. Furthermore, traditional preparation methods often rely on the external addition of metal salts to inert substrates (such as nickel foam NF). This method is not only cumbersome but also makes it difficult to precisely control the formation and distribution of active sites. The prepared catalyst is prone to aggregation and has weak binding to the substrate, affecting its activity and long-term stability.

[0004] Existing technologies include the preparation of cobalt-nickel-iron (Co-Ni-Fe) ternary metal phosphides by introducing metals, thereby optimizing catalytic performance through multi-metal synthesis. For example, CN202410568343.1 discloses a method for preparing ternary metal phosphides on a foamed nickel matrix, which involves hydrothermal reaction and subsequent phosphating with external cobalt and iron salts. The prepared cobalt-nickel-iron ternary phosphide catalyst exhibits excellent performance at 10 mA cm⁻¹. -2It exhibits HER and OER activity at low current densities. CN201811255631.2 and others also employ a hydrothermal synthesis method involving the addition of multiple metal salt precursors to a nickel foam substrate. These existing technologies require the nickel foam to be used solely as a carrier in a specific ratio with multiple metal salts (Co, Ni, Fe salts) before reaction, increasing cost and the difficulty of process control. Furthermore, these hydrothermal synthesis processes typically require high temperatures and long durations, increasing energy consumption.

[0005] Furthermore, traditionally prepared cobalt-nickel-iron ternary phosphides face difficulties in practical applications of complete water electrolysis. Even if they can be used for complete water electrolysis, industrial water electrolysis often requires operation at high current densities. For example, CN202410568343.1 requires 100 mA cm⁻¹. -2 The total water splitting voltage is as high as 1.879V, resulting in high energy consumption. Furthermore, the active materials in these methods are attached to the substrate surface through deposition or loading, resulting in weak bonding. During electrolysis, the active layer is prone to peeling off, affecting the long-term stability of the catalyst.

[0006] CN202411181141.8 discloses an in-situ growth of platinum-modified nickel-iron layered double hydroxide bifunctional material on a foamed nickel-iron substrate, its preparation method, and its application. The inventors previously achieved in-situ growth of nickel-iron hydroxide on a foamed nickel-iron substrate using a chloroplatinic acid system in an ether-alcohol-water mixed solvent. This system primarily relies on the in-situ reaction process under the combined action of noble metal ions and an acidic environment to construct the noble metal-modified layered double hydroxide structure.

[0007] However, the technical problem addressed in this invention differs significantly from the aforementioned systems. This invention aims to construct an integrated Co-Ni-Fe ternary metal phosphide electrode system that requires no additional iron or nickel precursors. Since cobalt salts lack the strong oxidizing characteristics of the chloroplatinic acid system, their in-situ growth mechanism differs fundamentally from the aforementioned noble metal modification systems. Furthermore, existing methods for preparing Co-Ni-Fe hydroxide precursors using cobalt salts typically require the addition of auxiliary precipitants such as urea and ammonium fluoride, combined with higher temperature conditions to promote growth.

[0008] The inventors unexpectedly discovered that in a specific chain-like ether-alcohol-water mixed solvent system, using only a cobalt chloride salt as the sole external metal source, without the need for additional auxiliary components such as iron, nickel, urea, or ammonium fluoride, can induce a foamed iron-nickel substrate to participate in an in-situ reaction and further construct a Co-Ni-Fe ternary metal phosphide nanosheet array structure. This not only simplifies the process and improves hydrogen evolution performance while maintaining excellent OER performance, but also enables applications with complete hydrolysis and ultra-long-term operational stability. Summary of the Invention

[0009] To address the problems in the background technology, the purpose of this invention is to propose a cobalt-nickel-iron ternary metal phosphide electrocatalytic electrode with foamed iron-nickel as a carrier, its preparation method, and its application.

[0010] To achieve the above objectives, the specific technical solution adopted by the present invention is as follows:

[0011] The present invention provides a cobalt-nickel-iron ternary metal phosphide electrocatalytic electrode based on a foamed iron-nickel support, comprising: a foamed iron-nickel support; and a cobalt-nickel-iron ternary metal phosphide active layer grown in situ on the foamed iron-nickel support.

[0012] The foamed iron-nickel carrier serves not only as a framework but also as a metal source for iron and nickel elements in the active layer.

[0013] Furthermore, due to the in-situ etching mechanism, the cobalt-nickel-iron ternary metal phosphide active layer prepared on the surface of foamed iron-nickel exhibits a three-dimensional nanosheet array structure.

[0014] The present invention also provides a method for preparing the above-mentioned electrocatalytic electrode, comprising the following steps:

[0015] (1) Immerse the foamed iron-nickel sheet in a 2.5~3.0M hydrochloric acid solution and sonicate for 5~15 minutes. Then clean the foamed iron-nickel substrate with water, acetone and ethanol respectively. The pretreatment step is to wash away the nickel oxide on the surface and expose the metallic nickel, which is convenient for the direct growth of hydroxides in the future.

[0016] (2) The treated foamed iron-nickel substrate is immersed in a mixed solution of cobalt salt containing chloride ions and hydrothermal reaction is carried out at 70-95℃; during the hydrothermal reaction, the iron and nickel on the surface of the foamed iron-nickel substrate are etched in situ into metal ions, which co-precipitate with cobalt ions in the solution, and a hydroxide precursor layer is grown in situ on the substrate surface.

[0017] Furthermore, when preparing the active layer, the ratio of the mass of added cobalt to the initial mass of the foamed iron-nickel carrier is 1%-20%; preferably, the mass fraction of the cobalt is 5%-12%, and most preferably 10%.

[0018] (3) The product after hydrothermal reaction and phosphorus source are subjected to phosphating treatment at 280-350℃ in an inert atmosphere to obtain the electrocatalytic electrode.

[0019] Furthermore, in step (1), the precursor salt containing chloride ions is cobalt chloride hexahydrate.

[0020] Furthermore, the mixed solution is a solvent system consisting of a chain ether, an alcohol, and water in a volume ratio of (4~5):(4~5):1. The hydrothermal reaction is carried out under conditions where no external acid or alkali is needed to adjust the pH, and the natural pH of the solution is 2-5. The chain ether is ethylene glycol diethyl ether, and the alcohol is ethanol.

[0021] Furthermore, in step (3), the phosphorus source is sodium hypophosphite.

[0022] The application of the electrocatalytic electrode in the alkaline water electrolysis hydrogen evolution reaction (HER).

[0023] The application of the electrocatalytic electrode in the alkaline water electrolysis oxygen evolution reaction (OER).

[0024] The electrocatalytic electrode described herein is used in the alkaline water electrolysis reaction as both the cathode and anode of the reaction.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] (1) The synthesis of traditional non-precious metal ternary catalysts requires high temperature, the addition of precipitants such as urea or ammonium fluoride, and the addition of iron and nickel salts to induce bulk precipitation. This invention utilizes the slightly acidic properties of cobalt chloride salt hydrolysis and the coordination etching of chloride ions with the chain ether-alcohol-water solvent to generate a synergistic effect. Fe and Ni released on the substrate co-precipitate with Co ions at the solid-liquid interface, and a cobalt-nickel-iron ternary phosphide active layer is grown in situ on the foamed iron-nickel support.

[0027] (2) Unlike existing technologies that utilize strong oxidants to form metal particle attachment structures through displacement reactions, this invention, through coordination etching, allows cobalt ions to replace the Ni-Fe hydroxide framework lattice, forming a homogeneous ternary metal precursor. Subsequent in-situ phosphating then forms a dense three-dimensional nanosheet framework. The active layer exhibits a three-dimensional nanosheet array structure on the surface of the foamed iron-nickel support, resulting in strong adhesion between the active layer and the substrate. This solves the problem of easy peeling of the catalyst layer under high-current gas evolution scouring, thus improving stability.

[0028] (3) This invention does not require precious metals, polymer binders, iron salts, nickel salts, or precipitants. It uses mild hydrothermal treatment and phosphating to generate cobalt-nickel-iron ternary metal phosphides. Under alkaline conditions, the electrode exhibits low HER and OER overpotentials at low current densities. The prepared dual-electrode total water splitting system exhibits low HER and OER overpotentials at 100 mA cm⁻¹. -2 At high current densities, the total water splitting voltage is low, reducing electrolysis energy consumption. Furthermore, it can operate stably for over 100 hours in the total water splitting system, solving the problem of easy deactivation of traditional catalysts. Attached Figure Description

[0029] Figure 1 These are microstructure and structural characterization images of the electrodes prepared in the embodiments and comparative examples of the present invention; wherein, (a)-(d) are CoNiFeP x / INF (Example 1), CoNiFe(OH) x / INF (Example 3), NiFeP x / INF (Example 4) and CoNiFeP x Scanning electron microscope (SEM) image of / NF (Example 5); (e)-(f) are CoNiFeP prepared in Example 1 of this invention. x / INF transmission electron microscope (TEM) and high resolution transmission electron microscope (HRTEM) images; (g) is the selected area electron diffraction (SAED) pattern; (h)-(m) are dark field images (HAADF-STEM) and their corresponding elemental distribution maps of Co, Ni, Fe, P and O.

[0030] Figure 2 The XRD pattern of the electrode prepared in Example 1 of this invention;

[0031] Figure 3 This is a comparison of the polarization curves of the hydrogen evolution reaction (HER) of the electrode prepared in Example 1 of the present invention and different comparative electrodes in 1.0 M KOH solution.

[0032] Figure 4 CoNiFeP with different cobalt mass fractions (1%, 2%, 5%, 10%, 15%) x Comparison of polarization curves of the hydrogen evolution reaction (HER) of water electrolysis at the / INF electrode.

[0033] Figure 5 This is a comparison of the polarization curves of the oxygen evolution reaction (OER) of the electrode prepared in Example 1 of the present invention and different comparative electrodes in 1.0 M KOH solution.

[0034] Figure 6 Comparison of polarization curves of oxygen evolution reaction (OER) in water electrolysis for CoNiFePx / INF electrodes with different cobalt mass fractions (1%, 2%, 5%, 10%, 15%).

[0035] Figure 7 CoNiFeP x Polarization curves of water electrolysis with / INF acting as both cathode and anode, and Pt / C / INF as cathode and RuO2 / INF as anode.

[0036] Figure 8 CoNiFeP x HER stability testing of the / INF electrode.

[0037] Figure 9 CoNiFeP x / INF serves as both the cathode and anode for the overall water electrolysis stability test.

[0038] Figure 10 The image shows a comparison of the HER polarization curves of electrodes prepared using cobalt chloride, cobalt nitrate, and cobalt acetate as precursors, respectively.

[0039] Figure 11 The OER polarization curves of electrodes prepared using cobalt chloride, cobalt nitrate, and cobalt acetate as precursors are compared.

[0040] Figure 12 The OER polarization curves of electrodes prepared with ether-alcohol-water and pure water as solvents are compared.

[0041] Figure 13 The image shows a comparison of the HER polarization curves of electrodes prepared using ether-alcohol-water and pure water as solvents, respectively. Detailed Implementation

[0042] The following example, using the growth of iron, cobalt, and nickel phosphides on the surface of a foamed iron-nickel substrate in a cobalt chloride solution, further illustrates the invention in detail. The scope of protection of this patent is not limited to the specific embodiments, but is limited by the claims.

[0043] Example 1

[0044] Iron-cobalt-nickel ternary composite phosphide modified foamed iron-nickel (CoNiFeP) x / INF) Electrode fabrication:

[0045] (1) Immerse a foamed iron-nickel sheet (Fe: Ni=3:7, purchased from Suzhou Welltech Optoelectronic Materials Co., Ltd.) with a pore size of 0.1 mm, a porosity of 95-98%, and a thickness of 1 mm in length × width = 1 cm × 2 cm in ultrasonication for 10 minutes in 3 M hydrochloric acid solution, and then clean the foamed iron-nickel substrate with water, acetone and ethanol respectively.

[0046] (2) Immerse 270 mg of cleaned foamed nickel in 7 mL of a mixed solution. This mixed solution was prepared by volume ratio of 3.2 mL ethanol, 3.1 mL ethylene glycol diethyl ether, and 0.7 mL deionized water, and contained 109 mg of cobalt chloride hexahydrate (the amount of cobalt added was calculated based on the mass of the added cobalt element being 10% of the mass of the foamed nickel substrate). The pH value of the mixed solution was measured to be approximately 3.0–4.5. After sealing the sample tube, it was placed in an 85°C water bath for 4 h.

[0047] After cooling to room temperature, the electrode was washed with ethanol and water and dried in a vacuum oven at 40°C for 2 hours. The dried electrode was then placed in a tube furnace, and 0.5 g of sodium hypophosphite monohydrate was placed upstream of nitrogen gas (approximately 5-10 cm). Phosphating was continued at 280°C for 2 hours at a heating rate of 2°C / min to obtain iron-cobalt-nickel foam (CoNiFeP) modified with a ternary composite phosphide. x / INF).

[0048] Figure 1 It is CoNiFeP x / INF scanning electron microscope and transmission electron microscope images. The images show an interlocking nanosheet structure, and the surface scan of the energy dispersive spectroscopy reveals that the nanosheets are composed of P, Fe, Co, and Ni.

[0049] The phase structure of the catalyst was further characterized using X-ray diffraction (XRD). Figure 2 As shown, CoNiFeP x The diffraction pattern of the / INF sample is dominated by strong diffraction peaks on the INF substrate. In addition, several weak diffraction peaks were observed at 40.7°, 47.2°, 53.0°, and 54.2°, which belong to the hexagonal M2P type phosphide phase. The relatively weak peak intensities indicate that the phosphide phase has low crystallinity.

[0050] Example 2 (Comparative example, different amounts of cobalt precursor)

[0051] Foamed iron-nickel modified with ternary composite hydroxides of iron, cobalt, and nickel in different cobalt addition ratios (wt. CoNiFeP) x Electrode preparation ( / INF): Compared with Example 1, the difference lies in the mass of cobalt chloride hexahydrate added when preparing the cobalt chloride solution. The cobalt was added at proportions of 1%, 2%, 5%, and 15% of the mass of the foamed iron-nickel substrate, respectively. Other operations were the same as in Example 1. These were named (1%CoNiFeP...). x / INF, 2%CoNiFeP x / INF, 5%CoNiFeP x / INF, and 15%CoNiFeP x / INF).

[0052] Example 3 (Comparative Example)

[0053] Iron-NiFe(OH) foam modified with iron, cobalt, and nickel ternary composite hydroxides x / INF) Electrode preparation: Compared with Example 1, the difference is that after hydrothermal treatment, the electrode obtained by drying is not subjected to further phosphating treatment, and other operations are the same as in Example 1.

[0054] Example 4 (Comparative Example)

[0055] Iron-nickel foam modified with iron-nickel binary composite hydroxide (NiFeP) x / INF) Electrode preparation: Compared with Example 1, the difference is that cobalt chloride is not added to the solution in the hydrothermal process, and the other operations are the same as in Example 1.

[0056] Example 5 (Comparative Example)

[0057] Nickel foam modified with iron, cobalt, and nickel ternary composite hydroxide (CoNiFeP) x Electrode preparation (NF): Compared with Example 1, the difference is that the substrate used is nickel foam. In the same mixed solvent as in Example 1, the same mass of cobalt chloride hexahydrate as in Example 1 is added, and ferric chloride is added in addition. The amount of ferric chloride added is determined by the following feed ratio: that is, the mass of the added iron element accounts for 2% of the mass of the nickel foam substrate. Other operations are the same as in Example 1.

[0058] A comparison of Examples 1 and 5 shows that, in Example 5, which uses a nickel foam substrate with external cobalt and iron sources, the catalyst performance is inferior to that of the in-situ etching growth method of this invention. This invention utilizes the substrate directly as the iron and nickel source, resulting in a stronger integrated bond and nanosheet array morphology between the active layer and the substrate, thus enhancing catalytic activity.

[0059] Comparative Example 1:

[0060] Compared with Example 1, Comparative Example 1 differs only in that: cobalt chloride hexahydrate is replaced with cobalt nitrate hexahydrate in equal molar amounts to ensure that the amount of cobalt added to the solution is consistent with that in Example 1. All other operating steps and conditions are exactly the same as in Example 1, and it is named cobalt nitrate / INF.

[0061] Comparative Example 2:

[0062] Comparative Example 2 differs from Example 1 only in that cobalt chloride hexahydrate is replaced with cobalt acetate tetrahydrate in equal molar amounts, while the amount of cobalt added to the solution remains the same as in Example 1. All other operations are identical to those in Example 1. The resulting cobalt acetate-derived phosphide electrode is named cobalt acetate / INF.

[0063] The electrochemical performance of Example 1 was compared with that of the above-mentioned comparative examples of cobalt nitrate / INF and cobalt acetate / INF using different cobalt salts.

[0064] In terms of electrochemical performance, electrodes obtained using cobalt chloride, cobalt nitrate, and cobalt acetate as precursors exhibited similar catalytic activities for the oxygen evolution reaction (OER), such as... Figure 11As shown. However, for the hydrogen evolution reaction (HER), the electrode of Example 1, prepared using cobalt chloride as a precursor, exhibits superior catalytic performance compared to the comparative electrodes using cobalt nitrate and cobalt acetate as precursors, respectively. Figure 10 As shown, it is demonstrated that in a specific mixed solvent system, the coordination etching effect of chloride ions in cobalt chloride salts is beneficial to the formation of three-dimensional nanosheet array structures.

[0065] Comparative Example 3:

[0066] Compared with Example 1, the only difference is that the 7 mL mixed solvent in step (2) is completely replaced with 7 mL deionized water, and the other operations are the same as in Example 1;

[0067] When pure water is used as the solvent, from Figure 13 It can be seen that the performance of HER is significantly reduced, and the overpotential is larger at the same current density.

[0068] Example 6 (Preparation of a commercial HER catalyst Pt / C / INF electrode)

[0069] A foamed iron-nickel sheet (Fe:Ni=3:7) with a pore size of 0.1 mm, a porosity of 95-98%, and a thickness of 0.1 mm, with a length × width of 2 cm × 3 cm, was immersed in a 3 M hydrochloric acid solution and sonicated at room temperature for 10 minutes. Then, the foamed iron-nickel substrate was cleaned with water, acetone, and ethanol, respectively.

[0070] Weigh 4.5 mg of Pt / C powder, add it to 900 µL of ethanol, sonicate for 5 min, then add 25 µL of Nafion, sonicate for 30 min, and then drop it evenly onto the surface of a foamed nickel substrate and dry to obtain a Pt / C / foamed nickel (Pt / C / INF) electrode.

[0071] Example 7 (Preparation of a commercial OER catalyst RuO2 / INF electrode)

[0072] A foamed iron-nickel sheet (Fe:Ni=3:7) with a pore size of 0.1 mm, a porosity of 95-98%, and a thickness of 0.1 mm (length × width = 2 cm × 3 cm) was immersed in a 3 M hydrochloric acid solution and sonicated for 10 minutes. Then, the foamed iron-nickel substrate was cleaned with water, acetone, and ethanol, respectively.

[0073] Weigh 4.5 mg of RuO2 powder, add it to 900 µL of ethanol, sonicate for 5 min, then add 25 µL of Nafion, sonicate for 30 min, and then drop it evenly onto the surface of a foamed nickel substrate and dry to obtain a RuO2 / foamed nickel (RuO2 / INF) electrode.

[0074] Example 8 Hydrogen Evolution Reaction (HER) Performance Testing

[0075] The iron-cobalt-nickel phosphate modified foam (CoNiFeP) prepared in Example 1 x Applications of INF materials as catalysts for the hydrogen evolution reaction (HER):

[0076] 0.5 × 1 cm CoNiFeP x The / INF electrode was used as the working electrode, the carbon rod as the counter electrode, and Hg / HgO as the reference electrode. The test was conducted using a CHI660E electrochemical workstation in a 1.0 M KOH electrolyte solution.

[0077] Linear sweep voltammetry (LSV) was used with a scan rate of 5 mV / s. -1 With an ohmic compensation of 85%, the hydrogen evolution performance was analyzed by obtaining polarization curves.

[0078] The HER polarization curves of the electrodes prepared in Examples 2, 3, 4, 5 and 6 were tested using the same method as above.

[0079] Figure 3 CoNiFeP x / INF (Example 1), CoNiFe(OH) x / INF (Example 3), NiFeP x / INF (Example 4), CoNiFeP x HER polarization curves of / NF (Example 5) and Pt / C / INF (Example 6). As shown in the figure, under the same current density, the CoNiFeP prepared by this method exhibits higher HER polarization. x / INF electrode at a current density of 10 mA cm⁻¹ -2 50 mA cm -2 and 100mA cm -2 At that time, its hydrogen evolution overpotential was only 46 mV, 168 mV and 198 mV, which is the lowest overpotential, indicating that it has higher hydrogen evolution activity.

[0080] Figure 4 HER polarization curves of electrodes prepared with different cobalt precursor feed ratios (Example 2). As shown in the figure, when the cobalt addition ratio increases from 1% to 15%, the overpotential first decreases and then increases at the same current density. The overpotential is lowest when the cobalt addition ratio is 10%, indicating that this is the optimal addition ratio.

[0081] Example 9 Oxygen Evolution Reaction (OER) Performance Testing

[0082] The CoNiFeP prepared in Example 1 xApplications of / INF materials as catalysts for the oxygen evolution reaction (OER):

[0083] 0.5 × 1 cm CoNiFeP x The / INF electrode was used as the working electrode, the carbon rod as the counter electrode, and Hg / HgO as the reference electrode. The test was conducted using a CHI660E electrochemical workstation in a 1.0 M KOH electrolyte solution.

[0084] Linear sweep voltammetry (LSV) was used with a scan rate of 5 mV / s. -1 With an ohmic compensation of 85%, the oxygen evolution performance was analyzed by obtaining polarization curves.

[0085] The OER polarization curves of the electrodes prepared in Examples 2, 3, 4 and 5 were tested using the same method as above.

[0086] Figure 5 CoNiFeP x / INF (Example 1), CoNiFe(OH) x / INF (Example 3), NiFeP x / INF (Example 4), CoNiFeP x The OER polarization curves of / NF (Example 5) and RuO2 / INF (Example 7) are shown in the figure. It can be seen from the figure that, under the same current density, the CoNiFeP prepared in this example... x / INF electrode at a current density of 10 mA cm⁻¹ -2 50 mA cm -2 and 100mA cm -2 At that time, its oxygen evolution overpotentials were 233 mV, 263 mV and 282 mV, with the lowest overpotential, indicating that it has the lowest energy consumption and high oxygen evolution activity.

[0087] Figure 6 OER polarization curves of electrodes prepared with different cobalt precursor feed ratios (Example 2). As shown in the figure, when the cobalt addition ratio increases from 1% to 15%, the overpotential initially decreases and then increases at the same current density. The lowest overpotential is observed when the cobalt addition ratio is 10%, indicating high oxygen evolution activity and representing the optimal feed ratio. Above 10%, the structure collapses due to the excessive amount, and the active sites are masked.

[0088] Example 10: Complete water hydrolysis performance test

[0089] The CoNiFeP prepared in Example 1 xThe / INF material was used as both a hydrogen evolution reaction (HER) and an oxygen evolution reaction (OER) electrode to study its overall water splitting performance: two 0.5 × 1 cm electrodes were cut out and a two-electrode system was adopted, with one electrode as the cathode (HER) and the other as the anode (OER). The tests were conducted in 1.0 M KOH electrolyte solution using a CHI660E electrochemical workstation.

[0090] Linear sweep voltammetry (LSV) was used with a scan rate of 5 mV / s. -1 With an ohmic compensation of 85%, polarization curves were obtained to analyze the overall water-splitting performance.

[0091] In addition, the RuO2 / foamed iron-nickel electrode prepared in Example 7 was used as the anode, and the Pt / C / foamed iron-nickel electrode prepared in Example 6 was used as the cathode. The water-splitting performance of this system was analyzed, and the test methods were the same as above.

[0092] Figure 7 The figure shows the polarization curves of the total water splitting tested in this embodiment. As can be seen from the figure, when the Co-NiFeP / INF prepared by this method is used as both the cathode and anode, to achieve 10 mA cm⁻¹... -2 and 100 mA cm -2 For the current density, only 1.52V and 1.72V are required; however, when Pt / C / INF is used as the cathode and RuO2 / INF as the anode, 1.57V and 1.93V are needed to reach 10 mA cm⁻¹. -2 and 100 mA cm -2 The increased current density leads to increased energy consumption.

[0093] Example 11 Stability Test

[0094] Figure 8 CoNiFeP x The HER-it curve of / INF was detected in 1.0 M KOH solution, and it can be seen that it is effective at a current density of 10 mA cm⁻¹. -2 It can remain stable for 100 hours, indicating that it has good stability.

[0095] Figure 9 CoNiFeP x Chronoamperometry was used to measure the total water splitting process when / INF was used as both the cathode and anode. As shown in the figure, this total water splitting system can be tested at a current density of 10 mA cm⁻¹. -2 It can maintain stability for at least 100 hours.

[0096] As can be seen from the above examples, by impregnating foamed iron-nickel with cobalt chloride solution, iron-cobalt-nickel multi-component composite phosphide can be obtained, which has good HER, OER and total water splitting performance.

[0097] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A cobalt-nickel-iron ternary metal phosphide electrocatalytic electrode based on a foamed iron-nickel support, characterized in that, include: A foamed iron-nickel carrier; and a cobalt-nickel-iron ternary phosphide active layer grown in situ on the foamed iron-nickel carrier; The foamed iron-nickel carrier serves as the metal source for iron and nickel elements in the active layer; the active layer is a three-dimensional nanosheet array structure on the surface of the foamed iron-nickel carrier.

2. A method for preparing a cobalt-nickel-iron ternary metal phosphide electrocatalytic electrode with foamed iron-nickel as a carrier as described in claim 1, characterized in that, Includes the following steps: (1) The foamed iron-nickel carrier is pretreated by pickling to remove the surface oxide layer; (2) The pretreated foamed nickel-copper support is immersed in a mixed solution containing cobalt chloride salt, with the solvent being chain ether, alcohol and water, the solution pH being 2-5, and heated at 70-95℃ to grow a cobalt-nickel-iron ternary hydroxide precursor layer in situ on the surface of the foamed nickel-copper support. (3) The product after the reaction in step (2) and the phosphorus source are subjected to phosphating treatment at 280-350°C in an inert atmosphere to obtain a cobalt-nickel-iron ternary metal phosphide electrocatalytic electrode based on a foamed iron-nickel support.

3. The preparation method according to claim 2, characterized in that, In step (1), the pretreatment conditions are as follows: the foamed iron-nickel carrier is immersed in a hydrochloric acid solution with a concentration of 2.5~3.0M and ultrasonically treated for 5~15 minutes, and then cleaned with water, acetone and ethanol respectively.

4. The preparation method according to claim 2, characterized in that, The volume ratio of the chain ether, alcohol, and water is (4~5):(4~5):1; the chain ether is ethylene glycol diethyl ether, and the alcohol is ethanol.

5. The preparation method according to claim 2, characterized in that, The cobalt chloride salt is cobalt chloride hexahydrate; the ratio of the total mass of cobalt added to the mixed solution to the initial mass of the foamed iron-nickel carrier in step (1) is 1% to 20%.

6. The preparation method according to claim 5, characterized in that, The ratio of the total mass of cobalt added to the mixed solution to the initial mass of the foamed iron-nickel carrier is 5% to 12%.

7. The preparation method according to claim 2, characterized in that, The phosphorus source is sodium hypophosphite.

8. The application of the cobalt-nickel-iron ternary metal phosphide electrocatalytic electrode with foamed iron-nickel as a carrier as described in claim 1 in alkaline water electrolysis.

9. The application according to claim 8, characterized in that, The applications include using the electrocatalytic electrode as the working electrode for the alkaline water electrolysis hydrogen evolution reaction, the alkaline water electrolysis oxygen evolution reaction, or simultaneously as the cathode and anode for the total water electrolysis reaction.

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